Photosensitive resin and its method for closed-loop recycling and circular 3d printing

2:

• The photosensitive resin according to claim 1, characterized in that when the precursor containing active functional groups is an aldehyde-containing precursor, the aldehyde-containing precursor is selected from vanillin, 4-hydroxybenzaldehyde, p-anisaldehyde, p-tertbutyl benzaldehyde, 4-cyanobenzaldehyde, 3-hydroxybenzaldehyde, benzaldehyde, the two-arm or multi-arm aldehydes derived from vanillin, 2-furaldehyde, 5-methylfurfural, 2-thiophenecarboxaldehyde, 5-methyl-2-thiophenecarboxaldehyde and one or more of the aldehyde-containing oligomers;
• when the precursor containing active functional groups is a carbonyl-containing precursor, the carbonyl-containing precursor is selected from 2,5-octanedione, spiro[5.5]undecane-3,9-dione, 2,7-dimethyloctane-3,6-dione, 2,15-hexadecanedione, 4,5-octanedione, 3-ethylpentane-2,4-dione, 1,3-diphenylpropanetrione, 1,3,5-tribromo-1,3,5-thiazinane-2,4,6-trione, 1,3-dibenzoylacetone, 2,3,5-hexanetrione, 2,3,5-heptanetrione and one or more types of ketone-containing oligomers;
• when the precursor containing active functional groups is a precursor with sterically hindered unsaturated double bonds, the precursor with sterically hindered unsaturated double bonds is selected from diisopropylidene oxide, 5-methylhexa-1,4-diene-3-one, neridienone B, 2,6-dimethyl-2,5,7-octatrien-4-one, 2,6-dimethyl-2,5-octadien-4-one, dimethylphenyl ketone, or one or more types of oligomers with hindered unsaturated double bonds;
• the thiol-containing precursor is selected from 2,2-(1,2-ethanediyldioxy)bis(ethanethiol), 4,4′-dithiol-stilbene, 1,11-undecanedithiol, dithiothreitol, 1,16-hexadecanedithiol, hexa (ethylene glycol)disulfide, 1,6-hexyldithiol, 2,3-pentanedithiol, 3,7-dithia-1,9-nonanedithiol, bis(3-mercaptopropionic acid)ethylene glycol, 2-ethyl-2-(mercaptomethyl)-1,3-propanedithiol, pentaerythritol tetrakis(3-mercaptoacetate), pentaerythritol tetra(3-mercaptopropionate), tetrakis (3-mercaptopropionic acid) tetraester or one or more types of oligomers with thiol as the terminal group.

5:

• A method for closed-loop recycling and circular 3D printing of a photosensitive resin, characterized in that the method comprises the following steps:
• (1) obtaining a 3D printed product after irradiating the photosensitive resin described in claim 1 with a light source in a photocuring 3D printing device;
• (2) dissolving a 3D printed product to be recycled, and after dissolution, depolymerizing the solution to generate oligomers and/or monomers with thiol and active functional group terminal groups, then adding a neutralizing agent to form a recycling system;
• (3) reintroducing a photoactivated catalyst into the recycling system to formulate a new photosensitive resin for circular 3D printing.

7:

• The method for closed-loop recycling and circular 3D printing of a photosensitive resin according to claim 5, is characterized in that, in the step (2), the 3D printed product to be recycled undergoes depolymerization under the action of a depolymerization catalyst, the residual photoactivated catalyst in the 3D printed product directly acts as the depolymerization catalyst, or additional acidic or basic agents are simultaneously added as depolymerization catalysts, the acidic agents are selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, acetic acid, carbonic acid, hydrocyanic acid, boric acid, citric acid, aluminum chloride, ferric chloride, zinc chloride, hexafluoroantimonic acid, boron trifluoride, boron trichloride, phosphorus pentachloride, antimony pentafluoride, triarylphosphonium salts, and diaryliodonium salts;
• the basic agents are selected from one or more of sodium bicarbonate, sodium carbonate, potassium carbonate, sodium acetate, sodium hydroxide, potassium hydroxide, methylamine, ethylamine, dimethylamine, trimethylamine, triethylamine, aniline, pyridine, pyrrole, imidazole, morpholine, piperidine, guanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1,8-Diazabicyclo[5.4.0]undec-7-ene or 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene;
• the amount of the depolymerization catalyst is 0.01 to 50 wt % of the mass of the photosensitive resin.