Multifunctional aliphatic polyurethane acrylate as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of 3D full-color printing ink-jet ink, and particularly relates to polyfunctional aliphatic polyurethane acrylate as well as a preparation method and application thereof. The preparation raw materials at least comprise the following components: caprolactone, a hydroxyl acrylate monomer, a catalyst, a polymerization inhibitor and an aliphatic isocyanate polymer, the molar ratio of the caprolactone to the hydroxyl acrylate monomer is (1-2): 1; when the polyfunctionality aliphatic polyurethane acrylate is applied to 3D full-color ink-jet ink, the curing speed is high, the strength is high, yellowing is not prone to occurring in single-layer stacking of 3D full-color printing of 15-30 microns, the original color can be displayed during color ink stacking, cracking and edge warping caused by shrinkage deformation are not prone to occurring, the interlayer binding force is good, and a high-quality product can be obtained.

Description

Technical Field

[0001] This invention belongs to the field of 3D full-color printing inkjet ink technology, specifically relating to a multifunctional aliphatic polyurethane acrylate, its preparation method, and its application. Background Technology

[0002] 3D full-color inkjet printing is an advanced additive manufacturing technology that combines the advantages of 3D printing and inkjet printing, enabling the creation of three-dimensional objects with rich colors and complex shapes. 3D full-color inkjet printing typically employs a layer-by-layer manufacturing principle, similar to traditional 3D printing. First, a 3D model is created using computer-aided design (CAD) software, and then the model is sliced ​​into a series of 2D layers. Next, based on this layer information, the printer uses inkjet heads to spray colored ink point by point onto the build platform, stacking them layer by layer to form the 3D object.

[0003] Photopolymer 3D full-color printing uses white ink as the blank (centimeter-thickness), colored ink (blue, red, yellow, black, etc., millimeter-thickness) for outer layer coloring and decoration, and water-soluble UV (water-based ultraviolet light curing material) as the support material. The support material is removed by soaking in water after printing. During printing, white ink, colored ink, and support material are sprayed simultaneously according to printing requirements. After printing, the support material is removed to achieve a full-color printing effect. Compared to traditional stereolithography (SLA), digital light processing (DLP), and LCD projection 3D printing methods, photopolymer 3D full-color printing offers rich colors and can directly reproduce product designs. It eliminates the need for coloring after printing a blank, as is the case with traditional 3D printing, saving processes and improving efficiency. However, 3D full-color printing uses inkjet printing, which places high demands on material selection. It requires low ink viscosity to ensure smooth ink flow, minimal standby time, and resistance to nozzle clogging and ink spillage. Simultaneously, the ink needs extremely fast photopolymerization speed. Since 3D full-color printed parts are typically in the centimeter range or larger, the white ink layer thickness must reach the centimeter level or higher. Furthermore, it requires rapid curing and high strength at 15-30μm layer thicknesses, without yellowing, cracking, shrinkage, or warping. Existing inkjet inks still suffer from slow curing speeds, low strength, and susceptibility to yellowing, aging, cracking, shrinkage, and warping at 15-30μm layer thicknesses in photopolymerized 3D full-color printing. Summary of the Invention

[0004] In order to solve the problems of the existing technology mentioned above.

[0005] The first aspect of this invention protects a multifunctional aliphatic polyurethane acrylate, wherein the raw materials for its preparation include at least the following components: caprolactone, hydroxy acrylate monomer, catalyst, polymerization inhibitor, and aliphatic isocyanate polymer. The molar ratio of caprolactone to hydroxyacrylate monomer is (1-2):1.

[0006] In this invention, multifunctionality refers to the presence of ≥2 reactive functional groups in a molecule.

[0007] In one optional embodiment, the hydroxyacrylate monomer has 5-10 carbon atoms and may include at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, and 4-hydroxybutyl acrylate.

[0008] In one optional embodiment, the mass ratio of the catalyst to the hydroxyacrylate monomer is (0.1-1):100.

[0009] In one optional embodiment, the mass ratio of the polymerization inhibitor to the hydroxyacrylate monomer is (0.1-1):100.

[0010] In one optional embodiment, the aliphatic isocyanate polymer has 20-40 carbon atoms and may include at least one of IPDI trimer (isophorone diisocyanate trimer), HDI dimer (hexamethylene diisocyanate dimer), HDI biuret (hexamethylene diisocyanate biuret), HDI trimer (hexamethylene diisocyanate trimer), and H6XDI trimer (hydrogenated phenylene diisocyanate trimer).

[0011] In one optional embodiment, the molar ratio of -NCO groups to hydroxyacrylate monomers in the aliphatic isocyanate polymer is (0.6-1):1, and can be optionally (0.9-1):1.

[0012] In this invention, the catalyst and polymerization inhibitor are conventional in the art. Typically, but not exclusively, the catalyst includes dibutyltin dilaurate; the polymerization inhibitor includes at least one of p-methoxyphenol, hydroquinone, 2,5-dimethyl-1,4-benzenediol, 2,6-di-tert-butyl-p-cresol, 2,2,6,6-tetramethylpiperidine oxide, phenothiazine, and tris(N-nitroso-N-phenylhydroxylamine)aluminum salt. Using dibutyltin dilaurate (DBTDL) as a catalyst provides catalytic activity in both steps S1 and S2. Through coordination of tin ions with hydroxyl groups, it activates the ester group or caprolactone ring, accelerating ring-opening and transesterification. Dibutyltin dilaurate is chosen because of its high activity and mild reaction conditions. These mild reaction conditions offer good compatibility with the double bonds in hydroxyl acrylates, preserving more double bonds. Simultaneously, dibutyltin dilaurate can also be used as a catalyst for the reaction of hydroxyl groups with -NCO groups, acting on the hydroxyl groups in the intermediate and the -NCO groups in the aliphatic isocyanate polymer. Tin ions coordinate with hydroxyl groups to activate ester groups or lactone rings, accelerating ring opening and transesterification.

[0013] A second aspect of this invention protects a method for preparing the aforementioned multifunctional aliphatic polyurethane acrylate, comprising the following steps: S1, caprolactone, hydroxyacrylate monomer, catalyst and polymerization inhibitor are mixed and subjected to the first thermal reaction to obtain the intermediate; S2, the intermediate obtained in S1 and the aliphatic isocyanate polymer are mixed to form a mixture, and a second thermal reaction is carried out to obtain the multifunctional aliphatic polyurethane acrylate.

[0014] In one optional embodiment, the temperature of the first thermal reaction is 85℃-120℃, and the time of the first thermal reaction is 10-20h.

[0015] In one optional embodiment, the temperature of the second thermal reaction is 60℃-85℃. When the content of -NCO groups in the reaction system is ≤0.1wt%, the second thermal reaction ends, and the multifunctional aliphatic polyurethane acrylate is obtained.

[0016] In this invention, the content of the -NCO group is determined using the standard di-n-butylamine titration method conventional in the art.

[0017] The third aspect of this invention protects a 3D printing inkjet ink, which, by weight, comprises the following components: 10-30 parts of the aforementioned multifunctional aliphatic polyurethane acrylate, 5-15 parts of monofunctional aliphatic polyurethane acrylate, 2-6 parts of photoinitiator, 20-40 parts of monofunctional photocurable monomer, 35-45 parts of difunctional photocurable monomer, 3-10 parts of multifunctional acrylate monomer, 0.2-15 parts of nano-pigment, and 0.5-2 parts of additives.

[0018] This invention incorporates a specific amount of the aforementioned multifunctional aliphatic polyurethane acrylate to prepare a 3D printing inkjet ink. When printing 3D full-color parts layer by layer to a thickness of 15-30 μm, it can achieve timely cross-linking and curing, layer-by-layer stacking, and improve interlayer bonding while preventing severe photocuring shrinkage that could lead to cracking of the molded parts. It exhibits high strength and resistance to yellowing and aging, ensuring consistent color over long-term storage. A specific amount of monofunctional aliphatic polyurethane acrylate enhances the toughness of the molded parts, preventing cracking and warping, and also reduces ink viscosity. A specific amount of photoinitiator rapidly decomposes to generate free radicals, promoting... The cross-linking reaction can also avoid excessive residue after curing, which can cause yellowing and aging; a specific amount of monofunctional photocurable monomer can reduce ink viscosity, a specific amount of difunctional photocurable monomer can strengthen the cross-linking network density and ensure strength; a specific amount of polyfunctional acrylate monomer can accelerate surface curing and improve surface drying performance; a specific amount of color paste can achieve color control; the synergistic effect of each component makes 3D full-color inkjet inks, when applied to 3D full-color printing, have a fast curing speed, high strength and are not prone to yellowing (the original colors can be displayed when the inks are stacked), are not prone to cracking, shrinkage and deformation leading to edge curling, and have good interlayer bonding, resulting in high-quality products.

[0019] In one alternative embodiment, the monofunctional aliphatic polyurethane acrylate includes at least one of Boxin B-39, Changxing 6101, Sartoma 9903NS, and RAHN Genomer* 1122.

[0020] In an optional embodiment, the photoinitiator comprises at least one of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone (CAS: 119313-12-1), isopropylthioxanthonone, 2,4-diethylthioxanthonone, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, bis(2,6-difluoro-3-(1H-pyrrolithyl-1)phenyl)titanium, methyl benzoylformate, benzoyl dimethyl ether, guanidine 2-(3-benzoylphenyl)propionate, 1-(anthraquinone-2-yl)ethylimidazolium carboxylate, tetraethylmiechone, and methyl o-benzoylbenzoate.

[0021] In one optional embodiment, the monofunctional photocurable monomer includes at least one of acrylate monomers and nitrogen / oxygen heterocyclic monomers, optionally including at least one of 2-phenylethyl acrylate, ethoxyphenoxy acrylate, 3,3,5-trimethylcyclohexyl acrylate, ethoxyethoxyethyl acrylate, glycidyl methacrylate, isobornyl acrylate, isobornyl methacrylate, tetrahydrofurfuryl acrylate, laurate acrylate, laurate methacrylate, cyclotrimethylolpropane methyl acetal acrylate, dicyclopentadiene ethoxy acrylate, acrylmorpholine, 2-ethyleneoxyethoxyethyl acrylate, and vinylmethyl oxazolidinone.

[0022] In one optional embodiment, the bifunctional photocurable monomer includes at least one of long-chain acrylate monomers, alicyclic acrylate monomers, aromatic acrylate monomers, and polyether acrylate monomers, optionally including dipropylene glycol diacrylate, neopentyl glycol diacrylate, propoxylated neopentyl glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol (200) diacrylate, polyethylene glycol (400) diacrylate, bisphenol A diacrylate ethoxylate, ethylene glycol dimethacrylate, and tricyclodecanediethanol diacrylate.

[0023] In one optional embodiment, the functionality of the multifunctional acrylate monomer is 3-5, and may optionally include at least one of tris(2-hydroxyethyl)isocyanurate triacrylate, trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, propoxylated trimethylolpropane trimethacrylate, ethoxylated trimethylolpropane trimethacrylate, propoxylated glycerol triacrylate, and bis(trimethylolpropane)tetraacrylate.

[0024] In this invention, the nano-pigment paste comprises acrylate monomers, a dispersant, and a pigment, enabling the pigment to exist uniformly and stably. Optionally, the mass ratio of the acrylate monomers, pigment, and dispersant is (40-60):(40-60):(3-10); alternatively, the mass ratio of the acrylate monomers, pigment, and dispersant is 45:50:5, 40:50:3, 40:40:6, 60:40:4, 40:60:10, etc., and is adaptively adjusted according to the selection of pigment to adapt to and ensure the overall quality of the ink. Viscosity and color; the acrylate monomer includes at least one of 1,6-hexanediol diacrylate and dipropylene glycol diacrylate; the pigment includes at least one of titanium dioxide paste, carbon black, phthalocyanine blue PB15:1, PB15:3, PB15:1, organic red pigments PR21, PR38, PR170, PR177, PV19, PV23, PR254, PR264, PR122, pigment yellow 12, pigment yellow 62, pigment yellow 183, pigment yellow 191, and CIPY150. The average particle size of the pigment is ≤300nm; the titanium dioxide pigment paste includes titanium dioxide nano-pigment paste and rutile titanium dioxide; optionally, the average particle size of the titanium dioxide nano-pigment paste is ≤300nm; optionally, the average particle size of the rutile titanium dioxide pigment paste formed by rutile titanium dioxide is ≤300nm, and the average particle size of the nano-pigment paste formed by other pigments is ≤150nm; the dispersant includes DISPERBYK-111.

[0025] In one optional embodiment, the additive includes at least one of leveling agent, dispersant, and defoamer, and may be a leveling agent. More preferably, the leveling agent includes at least one of polyacrylate type, organic modified polysiloxane, and polyether modified organic; and may also be BYK-333, BYK (Germany).

[0026] In one optional embodiment, the weight ratio of the multifunctional aliphatic polyurethane acrylate to the monofunctional aliphatic polyurethane acrylate is (11-15):(5-7).

[0027] In one alternative embodiment, the weight ratio of the multifunctional aliphatic polyurethane acrylate to the monofunctional photocurable monomer is 15:(20-25).

[0028] In one optional embodiment, the weight ratio of the multifunctional aliphatic polyurethane acrylate, the difunctional photocurable monomer, and the multifunctional acrylate monomer is 15:(40-45):(5-8).

[0029] In one alternative embodiment, the 3D printing inkjet ink has a viscosity of ≤12cps at 45°C, preferably 8-12cps.

[0030] A fourth aspect of this invention protects a 3D full-color printed part, wherein the 3D full-color printed part is produced by inkjet printing using the aforementioned 3D printing inkjet ink.

[0031] The technical solution of this invention has the following advantages: 1. This invention provides a multifunctional aliphatic polyurethane acrylate by introducing caprolactone and controlling the molar ratio of caprolactone to hydroxy acrylate monomer to (1-2):1 to obtain an intermediate. By utilizing the synergistic effect of aliphatic isocyanate polymer and intermediate, the significant shrinkage problem that occurs when conventional multifunctional aliphatic polyurethane acrylate is applied to 3D printing inkjet ink during photocuring can be effectively avoided. This not only improves the photocuring speed and strength, but also reduces the problems of yellowing, cracking, shrinkage deformation and warping caused by yellowing, cracking and warping. In addition, it can ensure that the surface of the 3D printed part is dry.

[0032] 2. When the multifunctional aliphatic polyurethane acrylate of this invention is used to prepare 3D full-color inkjet ink, it can further enhance the toughness of the molded parts by synergizing with monofunctional aliphatic polyurethane acrylate and other materials, thus avoiding cracking and warping. The preferred combination with raw materials such as monofunctional photocurable monomers, difunctional photocurable monomers, and multifunctional acrylate monomers can reduce the viscosity of the ink, thereby adapting it to 3D inkjet printing. More importantly, when printing and stacking layers of 15-30μm during 3D printing, cross-linking and curing can be achieved in time, accelerating curing and allowing for layer-by-layer molding. When the colored inks are stacked, the original colors can be displayed. Attached Figure Description

[0033] Figure 1 The white blank formed by printing with white ink in Example 1 is used as the base blank for forming a 3D full-color printed part. Detailed Implementation

[0034] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described herein. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0035] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0036] The titanium dioxide nano-color paste used in the application examples and comparative examples of this invention is prepared as follows: 45 parts of 1,6-hexanediol-diacrylate (HDDA), 50 parts of titanium dioxide, and 5 parts of dispersant DISPERBYK-111 are dispersed evenly using a high-speed disperser, and then ground using a sand mill (equipment model NMM-1L, Boyi Industrial Technology) to obtain titanium dioxide nano-color paste with an average particle size ≤300nm (detected by NICOMP N3000 particle size analyzer) for later use.

[0037] In the 3D full-color inkjet printing process, white ink is used to form the blank, followed by full-color printing with other color inks such as blue, red, yellow, and black. The color pastes for these other colors can be commercially available nano-color pastes of the corresponding colors, or nano-color pastes of the corresponding colors produced by Moku New Materials Co., Ltd. The nano-color pastes include acrylate monomers, dispersants, and pigments, ensuring uniform and stable pigment distribution. Optionally, the mass ratio of the acrylate monomers, pigments, and dispersants is (40-60):(40-60):(3-10); alternatively, the mass ratio of the acrylate monomers, pigments, and dispersants is 45:50:5, 40:50:3, or 40:40. The ratios 6, 60:40:4, 40:60:10, etc., are adaptively adjusted according to the pigment selection to adapt to and ensure the overall viscosity and color of the ink; the acrylate monomer includes at least one of 1,6-hexanediol diacrylate and dipropylene glycol diacrylate; the pigments include at least one of titanium dioxide paste, carbon black, phthalocyanine blue PB15:1, PB15:3, PB15:1, organic red pigments PR21, PR38, PR170, PR177, PV19, PV23, PR254, PR264, PR122, pigment yellow 12, pigment yellow 62, pigment yellow 183, pigment yellow 191, and CIPY150. The average particle size of the pigment is ≤300nm; the titanium dioxide pigment paste includes titanium dioxide nano-pigment paste and rutile titanium dioxide; optionally, the average particle size of the titanium dioxide nano-pigment paste is ≤300nm; optionally, the average particle size of the rutile titanium dioxide pigment paste formed by rutile titanium dioxide is ≤300nm, and the average particle size of the nano-pigment paste formed by other pigments is ≤150nm; the dispersant includes DISPERBYK-111.

[0038] In the 3D full-color inkjet printing process, white is used as the blank, combined with other colors such as blue, red, yellow, and black. The resulting 3D full-color printed parts can be various toys, souvenir products, and small items. The application examples and comparative examples of this invention only use white ink made from white pigment for printing tests to simulate actual use. In practical applications, different colored pigments can be adaptively replaced with titanium dioxide nano-pigment. The application examples and comparative examples of this invention are merely illustrative examples and do not limit the scope of the invention.

[0039] Example 1 This embodiment provides a multifunctional aliphatic polyurethane acrylate and its preparation method, including the following steps: S1, 114.14g caprolactone, 116.12g hydroxyethyl acrylate, 0.12g dibutyltin dilaurate (DBTDL), and 0.12g p-methoxyphenol were added sequentially to a reaction vessel and reacted at 110℃ for 14h to obtain an intermediate; S2, the intermediate obtained in step S1 is added to a reactor containing 169.8g of Bayer's N3900 (main component HDI trimer, of which NCO mass fraction content is 23.5%), the reaction temperature is maintained at 70℃, and the change in the content of -NCO groups in the reactor material is detected. When the content of -NCO groups in the mixture is ≤0.1wt%, multifunctional aliphatic polyurethane acrylate is obtained.

[0040] Example 2 This embodiment provides a multifunctional aliphatic polyurethane acrylate and its preparation method, including the following steps: S1, 216.87g caprolactone, 130.14g hydroxypropyl acrylate, 0.26g dibutyltin dilaurate (DBTDL), and 0.26g p-methoxyphenol were added sequentially to a reaction vessel and reacted at 110℃ for 14h to obtain an intermediate; S2, the intermediate obtained in step S1 is added to a reactor containing 178.7g of Bayer's N3900 (main component HDI trimer, of which NCO mass fraction content is 23.5%), the reaction temperature is maintained at 70℃, and the change in the content of -NCO groups in the reactor material is detected. When the content of -NCO groups in the mixture is ≤0.1wt%, multifunctional aliphatic polyurethane acrylate is obtained.

[0041] Example 3 This embodiment provides a multifunctional aliphatic polyurethane acrylate and its preparation method, including the following steps: S1, 114.14g caprolactone, 144.17g 4-hydroxybutyl acrylate, 0.22g dibutyltin dilaurate (DBTDL), and 0.22g p-methoxyphenol were added sequentially to a reaction vessel and reacted at 110℃ for 14h to obtain an intermediate; S2, the intermediate obtained in step S1 is added to a reactor containing 341.46g of Bayer's Z4470BA (main component IPDI trimer, solvent is butyl acetate, solid content 70%, of which the mass fraction of NCO in Z4470BA is 11.9%), the reaction temperature is maintained at 70℃, and the change in the content of -NCO groups in the reactor material is detected. When the content of -NCO groups in the mixture is ≤0.1wt%, multifunctional aliphatic polyurethane acrylate is obtained.

[0042] Example 4 This embodiment provides a multifunctional aliphatic polyurethane acrylate and its preparation method, including the following steps: S1, 114.14g caprolactone, 116.12g hydroxyethyl acrylate, 0.51g dibutyltin dilaurate (DBTDL), and 0.51g p-methoxyphenol were added sequentially to a reaction vessel and reacted at 120℃ for 10h to obtain an intermediate; S2, the intermediate obtained in step S1 is added to a reactor containing 169.8g of Bayer's N3900 (main component HDI trimer, of which NCO mass fraction content is 23.5%), the reaction temperature is maintained at 75℃, and the change in the content of -NCO groups in the reactor material is detected. When the content of -NCO groups in the mixture is ≤0.1wt%, multifunctional aliphatic polyurethane acrylate is obtained.

[0043] Example 5 This embodiment provides a multifunctional aliphatic polyurethane acrylate and its preparation method, including the following steps: S1, 114.14g caprolactone, 116.12g hydroxyethyl acrylate, 0.12g dibutyltin dilaurate (DBTDL), and 0.11g p-methoxyphenol were added sequentially to a reaction vessel and reacted at 100℃ for 17h to obtain an intermediate; S2, the intermediate obtained in step S1 is added to a reactor containing 169.8g of Bayer's N3900 (main component HDI trimer, of which NCO mass fraction content is 23.5%), the reaction temperature is maintained at 80℃, and the change in the content of -NCO groups in the reactor material is detected. When the content of -NCO groups in the mixture is ≤0.1wt%, multifunctional aliphatic polyurethane acrylate is obtained.

[0044] Example 6 This embodiment provides a multifunctional aliphatic polyurethane acrylate and its preparation method, including the following steps: S1, 114.14g caprolactone, 116.12g hydroxyethyl acrylate, 1.16g dibutyltin dilaurate (DBTDL), and 1.16g p-methoxyphenol were added sequentially to a reaction vessel and reacted at 85℃ for 20h to obtain an intermediate; S2, the intermediate obtained in step S1 is added to a reactor containing 169.8g of Bayer's N3900 (main component HDI trimer, of which NCO mass fraction content is 23.5%), the reaction temperature is maintained at 60℃, and the change in the content of -NCO groups in the reactor material is detected. When the content of -NCO groups in the mixture is ≤0.1wt%, multifunctional aliphatic polyurethane acrylate is obtained.

[0045] Comparative Example 1 This comparative example provides a method for preparing multifunctional aliphatic polyurethane acrylate, comprising the following steps: 116.12g of hydroxyethyl acrylate, 0.12g of dibutyltin dilaurate (DBTDL), and 0.12g of p-methoxyphenol were sequentially added to a reactor containing 169.8g of Bayer N3900 (main component HDI trimer, with an NCO mass fraction of 23.5%). The reaction temperature was maintained at 70℃, and the change in the -NCO group content in the reactor was monitored. When the -NCO group content in the mixture was ≤0.1wt%, aliphatic polyurethane acrylate was obtained.

[0046] Comparative Example 2 This comparative example provides a method for preparing a multifunctional aromatic polyurethane acrylate, comprising the following steps: S1, 114.14g caprolactone, 116.12g hydroxyethyl acrylate, 0.12g dibutyltin dilaurate (DBTDL), and 0.12g p-methoxyphenol were added sequentially to a reaction vessel and reacted at 110℃ for 14h to obtain an intermediate; S2, the intermediate obtained in step S1 is added to a reactor containing 82.72g of Bayer's Desmodur T80 (main component toluene diisocyanate (TDI), with an NCO mass fraction of 48%), the reaction temperature is maintained at 70°C, and the change in the content of -NCO groups in the reactor material is detected. When the content of -NCO groups in the mixture is ≤0.1wt%, aromatic polyurethane acrylate is obtained.

[0047] Comparative Example 3 This embodiment provides a method for preparing multifunctional aliphatic polyurethane acrylate, including the following steps: S1, 342.42g caprolactone, 116.12g hydroxyethyl acrylate, 0.12g dibutyltin dilaurate (DBTDL), and 0.12g p-methoxyphenol were added sequentially to a reaction vessel and reacted at 110℃ for 14h to obtain an intermediate; S2, the intermediate obtained in step S1 is added to a reactor containing 169.8g of Bayer N3900 (main component HDI trimer, of which NCO mass fraction content is 23.5%), the reaction temperature is maintained at 70℃, and the change in the content of -NCO groups in the reactor material is detected. When the content of -NCO groups in the mixture is ≤0.1wt%, aliphatic polyurethane acrylate is obtained.

[0048] Comparative Example 4 This comparative example provides a method for preparing multifunctional aliphatic polyurethane acrylate, comprising the following steps: S1, 114.14g of polycaprolactone diol (weight average molecular weight 1000), 116.12g of hydroxyethyl acrylate, 0.12g of dibutyltin dilaurate (DBTDL), and 0.12g of p-methoxyphenol were added sequentially to a reaction vessel and reacted at 110℃ for 14h to obtain an intermediate; S2, the intermediate obtained in step S1 is added to a reactor containing 169.8g HDI (Bayer N3900), the reaction temperature is maintained at 70℃, and the change in the content of -NCO groups in the reactor material is detected. When the content of -NCO groups in the mixture is ≤0.1wt%, aliphatic polyurethane acrylate is obtained.

[0049] Application Example 1 This application example provides a 3D printing inkjet ink. The raw materials for the 3D printing inkjet ink, by weight, include: 15 parts of the multifunctional aliphatic polyurethane acrylate obtained in Example 1, 5 parts of the monofunctional aliphatic polyurethane acrylate (6101, Changxing Chemical), 3.5 parts of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide photoinitiator (JRCURE-1108, Tianjin Jiuri New Material Co., Ltd.), and phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide photoinitiator (JRCURE-1110). 0.9 parts of the following: vinyl methyl oxazolidinone (VMOX, BASF), 15 parts of tetrahydrofurfuryl acrylate (THFA, Changxing Chemical), 10 parts of tricyclodecanediethanol diacrylate (TCDDA, Changxing Chemical), 12 parts of 1,6-hexanediol diacrylate (HDDA, Changxing Chemical), 28 parts of ethoxylated trimethylolpropane triacrylate ((EO)3TMPTA, Changxing Chemical), 5 parts of titanium dioxide nano-color paste, and 0.6 parts of leveling agent (BYK-333, BYK, Germany).

[0050] The 3D printing inkjet ink provided in this application embodiment is obtained by uniformly mixing the above-mentioned 3D printing inkjet ink raw materials using a high-speed disperser; the white preform formed by printing the 3D printing inkjet ink is used as the base material for forming 3D full-color printed parts, such as... Figure 1 As shown.

[0051] Application Example 2 This application example provides a 3D printing inkjet ink, which is similar to application example 1, except that the multifunctional aliphatic polyurethane acrylate obtained in example 1 is replaced with the multifunctional aliphatic polyurethane acrylate obtained in example 2.

[0052] Application Example 3 This application example provides a 3D printing inkjet ink, which is similar to application example 1, except that the multifunctional aliphatic polyurethane acrylate obtained in example 1 is replaced with the multifunctional aliphatic polyurethane acrylate obtained in example 3.

[0053] Application Example 4 This application example provides a 3D printing inkjet ink, which is similar to application example 1, except that the multifunctional aliphatic polyurethane acrylate obtained in example 1 is replaced with the multifunctional aliphatic polyurethane acrylate obtained in example 4.

[0054] Application Example 5 This application example provides a 3D printing inkjet ink, which is similar to application example 1, except that the multifunctional aliphatic polyurethane acrylate obtained in example 1 is replaced with the multifunctional aliphatic polyurethane acrylate obtained in example 5.

[0055] Application Example 6 This application example provides a 3D printing inkjet ink, which is the same as application example 1, except that the multifunctional aliphatic polyurethane acrylate obtained in example 1 is replaced with the multifunctional aliphatic polyurethane acrylate obtained in example 6.

[0056] Application Example 7 This application example provides a 3D printing inkjet ink, which differs from application example 1 in that: Example 1 yielded 20 parts of multifunctional aliphatic polyurethane acrylate and 10 parts of monofunctional aliphatic polyurethane acrylate (6101, Changxing Chemical). 35 parts of monofunctional photocurable monomer, including 17.5 parts of vinyl methyl oxazolidinone (VMOX, BASF) and 17.5 parts of tetrahydrofurfuryl acrylate (THFA, Changxing Chemical). 35 parts of a bifunctional photocurable monomer, including 17.5 parts of tricyclodecanediethanol diacrylate (TCDDA, Changxing Chemical) and 17.5 parts of 1,6-hexanediol diacrylate (HDDA, Changxing Chemical). Eight parts of ethoxylated trimethylolpropane triacrylate ((EO)3TMPTA, Changxing Chemical).

[0057] Application Example 8 This application example provides a 3D printing inkjet ink, which differs from application example 2 in that: Example 2 yielded 20 parts of multifunctional aliphatic polyurethane acrylate and 12 parts of monofunctional aliphatic polyurethane acrylate (6101, Changxing Chemical). 35 parts of monofunctional photocurable monomer, including 15 parts of vinyl methyl oxazolidinone (VMOX, BASF) and 15 parts of tetrahydrofurfuryl acrylate (THFA, Changxing Chemical). 40 parts of a bifunctional photocurable monomer, including 20 parts of tricyclodecanediethanol diacrylate (TCDDA, Changxing Chemical) and 20 parts of 1,6-hexanediol diacrylate (HDDA, Changxing Chemical). Five parts of ethoxylated trimethylolpropane triacrylate ((EO)3TMPTA, Changxing Chemical).

[0058] Application Example 9 This application example provides a 3D printing inkjet ink, which differs from application example 3 in that: Example 3 yielded 15 parts of multifunctional aliphatic polyurethane acrylate and 12 parts of monofunctional aliphatic polyurethane acrylate (6101, Changxing Chemical). 30 parts of monofunctional photocurable monomer, including 15 parts of vinyl methyl oxazolidinone (VMOX, BASF) and 15 parts of tetrahydrofurfuryl acrylate (THFA, Changxing Chemical). 35 parts of a bifunctional photocurable monomer, including 17.5 parts of tricyclodecanediethanol diacrylate (TCDDA, Changxing Chemical) and 17.5 parts of 1,6-hexanediol diacrylate (HDDA, Changxing Chemical). Four parts of ethoxylated trimethylolpropane triacrylate ((EO)3TMPTA, Changxing Chemical).

[0059] Application Comparative Example 1 This application provides a 3D printing inkjet ink in the comparative example, following the method of application example 1, except that the multifunctional aliphatic polyurethane acrylate obtained in example 1 is replaced with the multifunctional aliphatic polyurethane acrylate obtained in comparative example 1.

[0060] Application Comparative Example 2 This application provides a 3D printing inkjet ink in the comparative example, following the method of application example 1, except that the multifunctional aliphatic polyurethane acrylate obtained in example 1 is replaced with the multifunctional aromatic polyurethane acrylate obtained in comparative example 2.

[0061] Application Comparative Example 3 This application provides a 3D printing inkjet ink in the comparative example, following the method of application example 1, except that the multifunctional aliphatic polyurethane acrylate obtained in example 1 is replaced with the multifunctional aliphatic polyurethane acrylate obtained in comparative example 3.

[0062] Application Comparative Example 4 This application provides a 3D printing inkjet ink in the comparative example, following the method of application example 1, except that the multifunctional aliphatic polyurethane acrylate obtained in example 1 is replaced with the multifunctional aliphatic polyurethane acrylate obtained in comparative example 4.

[0063] Application Comparative Example 5 This application provides a 3D printing inkjet ink in the comparative example, following the method of application example 7, except that: there is an excessive amount of multifunctional acrylate monomer, namely 15 parts of ethoxylated trimethylolpropane triacrylate.

[0064] Application Comparative Example 6 This application provides a 3D printing inkjet ink in comparison to Application Example 8, except that the bifunctional photocurable monomer is replaced with a monofunctional photocurable monomer, that is, tricyclodecanediethanol diacrylate (TCDDA, Changxing Chemical) is replaced with vinylmethyl oxazolidinone (VMOX, BASF), and 1,6-hexanediol diacrylate (HDDA, Changxing Chemical) is replaced with tetrahydrofurfuryl acrylate (THFA, Changxing Chemical).

[0065] Application Comparative Example 7 This application provides a 3D printing inkjet ink in comparison to the method of application example 9, except that: the monofunctional aliphatic polyurethane acrylate is replaced with a polyfunctional aliphatic polyurethane acrylate, that is, vinyl methyl oxazolidinone (VMOX, BASF) and tetrahydrofurfuryl acrylate are replaced with the polyfunctional aliphatic polyurethane acrylate obtained in example 3.

[0066] Test case The viscosity of the 3D printing inkjet inks obtained in the application examples and comparative examples at 45°C was tested using a Bollerfeld DVN rotational viscometer. The test results are shown in Table 1. The 3D printing inkjet inks obtained from the application examples and comparative examples were filtered using 0.45μm and 0.22μm PP (polypropylene) filters for later use. The filtered inks were then used for 3D printing on a Ricoh G6 flatbed printer (Hantuo UV flatbed printer, model HT3116UV, printhead model MH5320). Printing parameters were set as follows: single channel 8-pass, enhanced ink volume, medium feathering, resolution 726×600, light source: UV-LED 395nm cold light source, irradiation power 8W, ink swatches, 18μm thickness per print, continuous printing with multiple stacks, and a test sample with dimensions of 30mm×30mm×3mm (length×width×height). After printing, the photocuring speed, toughness, tensile strength, and yellowing resistance were tested and evaluated. The test results are shown in Table 1. The evaluation criteria for surface drying properties (characterizing photocuring speed), toughness, tensile strength, and aging resistance after printing are as follows: (1) Surface drying performance: After each printing, test the curing and drying status of the sample surface by touch. If there is obvious sticky substance on the fingertip after lightly touching the coating surface, clear fingerprints or indentations appear on the coating surface, or even the finger may stick to the coating, it is grade 1 (not surface dry); if you can feel slight stickiness when you lightly touch the coating surface, but no substance sticks to the fingertip, and there are no fingerprints or only very faint traces left on the coating surface after you remove your finger, and the traces can disappear quickly, it is grade 2 (semi-surface dry / slightly sticky); if there is no stickiness when you lightly touch the coating surface, and the surface is smooth after you remove your finger, with no fingerprints or indentations, and the coating has formed a dry surface layer, with only a very slight "slippery feeling" (non-sticky), it is grade 3 (completely surface dry).

[0067] (2) Toughness: According to ASTM D256 standard, test the notched impact strength of the specimen. If the impact strength is ≥22J / m, it is considered qualified, which means the toughness is qualified; otherwise, the toughness is unqualified.

[0068] (3) Tensile strength: The tensile strength shall be tested using a universal testing machine in accordance with GB / T 1040.2-2006 standard. Tensile strength ≥ 45MPa is qualified, otherwise it is unqualified.

[0069] (4) Aging resistance: Xenon aging lamp was used. Test conditions: light source wavelength 340nm, temperature 60℃, humidity 60%, 50W / m 2 Irradiate the sample with high intensity for 1000 hours, and test the color difference value (ΔE) with a colorimeter. ΔE ≤ 1 is considered qualified, otherwise it is considered unqualified.

[0070] (5) Water resistance: Weigh the printed part (remove the support material) and record the mass as m1. Immerse the weighed printed part in clean water at 40℃ for 72 hours. The appearance of the printed part should not change (the colored ink and white ink should not separate, peel off, or fade). Water absorption test method: After taking out the printed part, wipe the surface of the printed part dry with a lint-free cloth, and then place it naturally in an environment with a temperature of 20-25℃ and a humidity of ≤55% for 2 hours. Weigh the mass of the printed part after treatment and record it as m2. (m1-m2) / m1×100%. A water absorption rate of <0.5% is acceptable.

[0071] Table 1. Test results of application examples and comparative examples.

[0072] (Note: The viscosity of Comparative Examples 4 and 7 was too high, making direct inkjet printing impossible and resulting in poor printing performance, poor standby time, and poor smoothness. " / " indicates that the test could not be conducted.) As shown in Table 1, the multifunctional aliphatic polyurethane acrylate used in the application examples of this invention is obtained by reacting caprolactone, hydroxy acrylate monomers, catalysts, polymerization inhibitors, and aliphatic isocyanate polymers. The 3D printing inkjet ink prepared by further combining it with other components has excellent photocuring speed, tensile strength, toughness (impact strength), aging resistance, and water resistance. It can meet the high requirements of materials when using inkjet printing for 3D full-color printing, such as low ink viscosity, ensuring ink flow, standby time, and less clogging and ink scattering. More importantly, the printing ink has an extremely fast photocuring speed, obtains excellent surface drying performance, and has comprehensive properties such as strength, toughness, and aging resistance.

[0073] Comparative Example 1 uses aliphatic polyurethane acrylate without caprolactone modification. It is obtained directly from the reaction of hydroxyethyl acrylate and HDI trimer. The resulting inkjet ink has acceptable photocuring speed, tensile strength, and aging resistance, but its toughness / impact strength is unacceptable, and it is prone to edge chipping and cracking.

[0074] Comparative Example 2 uses aromatic isocyanate. The resulting inkjet ink has acceptable photocuring speed and tensile strength, but poor toughness / impact strength, is prone to yellowing, and fails to meet aging resistance standards.

[0075] The photocuring speed of the inkjet ink prepared by using excessive caprolactone-modified hydroxy acrylate monomer in Comparative Example 3 was not up to standard.

[0076] The inkjet ink prepared using polycaprolactone diol in Comparative Example 4 has a higher viscosity and is not suitable for the speed requirements of 3D inkjet printing and photopolymerization.

[0077] The inkjet ink prepared by using more multifunctional acrylate monomers in Comparative Example 5 had defects such as poor toughness.

[0078] The inkjet ink prepared by using more monofunctional photocurable monomers in Comparative Example 6 had unsatisfactory tensile strength and water resistance.

[0079] The printing ink prepared by applying more multifunctional aliphatic polyurethane acrylate as in Comparative Example 7 has a higher viscosity and is not suitable for the speed requirements of 3D inkjet printing and photopolymerization.

[0080] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A multifunctional aliphatic polyurethane acrylate, characterized in that, Its preparation raw materials include at least the following components: caprolactone, hydroxy acrylate monomer, catalyst, polymerization inhibitor, and aliphatic isocyanate polymer; The molar ratio of caprolactone to hydroxyacrylate monomer is (1-2):

1.

2. The multifunctional aliphatic polyurethane acrylate according to claim 1, characterized in that, The hydroxyacrylate monomer has 5-10 carbon atoms; And / or, the aliphatic isocyanate polymer has 20-40 carbon atoms; And / or, the molar ratio of -NCO groups to hydroxyacrylate monomers in the aliphatic isocyanate polymer is (0.6-1):

1.

3. The multifunctional aliphatic polyurethane acrylate according to claim 2, characterized in that, The hydroxy acrylate monomer includes at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, and 4-hydroxybutyl acrylate; And / or, the aliphatic isocyanate polymer includes at least one of IPDI trimer, HDI dimer, HDI biuret, HDI trimer, and H6XDI trimer; And / or, the molar ratio of -NCO groups to hydroxyacrylate monomers in the aliphatic isocyanate polymer is (0.9-1):

1.

4. A method for preparing a multifunctional aliphatic polyurethane acrylate according to any one of claims 1-3, characterized in that, Includes the following steps: S1, caprolactone, hydroxyacrylate monomer, catalyst and polymerization inhibitor are mixed and subjected to the first thermal reaction to obtain the intermediate; S2, the intermediate obtained in S1 and the aliphatic isocyanate polymer are mixed to form a mixture, and a second thermal reaction is carried out to obtain the multifunctional aliphatic polyurethane acrylate.

5. The method for preparing multifunctional aliphatic polyurethane acrylate according to claim 4, characterized in that, The temperature of the first thermal reaction is 85℃-120℃, and the time is 10-20h; And / or, the temperature of the second thermal reaction is 60℃-85℃, and the second thermal reaction ends when the content of -NCO groups in the reaction system is ≤0.1wt%, thus obtaining the multifunctional aliphatic polyurethane acrylate.

6. A 3D printing inkjet ink, characterized in that, The product comprises, by weight, the following components: 10-30 parts of the multifunctional aliphatic polyurethane acrylate as described in any one of claims 1-3, 5-15 parts of the monofunctional aliphatic polyurethane acrylate, 2-6 parts of the photoinitiator, 20-40 parts of the monofunctional photocurable monomer, 35-45 parts of the difunctional photocurable monomer, 3-10 parts of the multifunctional acrylate monomer, 0.2-15 parts of the nano-color paste, and 0.5-2 parts of the additives.

7. The 3D printing inkjet ink according to claim 6, characterized in that, The weight ratio of the multifunctional aliphatic polyurethane acrylate to the monofunctional aliphatic polyurethane acrylate is (11-15):(5-7). And / or, the weight ratio of the multifunctional aliphatic polyurethane acrylate to the monofunctional photocurable monomer is 15:(20-25). And / or, the weight ratio of the multifunctional aliphatic polyurethane acrylate, the difunctional photocurable monomer, and the multifunctional acrylate monomer is 15:(40-45):(5-8).

8. The 3D printing inkjet ink according to claim 6, characterized in that, The 3D printing inkjet ink has a viscosity of ≤12cps at 45℃.

9. The 3D printing inkjet ink according to claim 8, characterized in that, The 3D printing inkjet ink has a viscosity of 8-12 cps at 45°C.

10. A 3D full-color printed part, characterized in that, The 3D full-color printed part is produced by inkjet printing using the 3D printing inkjet ink described in any one of claims 6-9.

Images