CN-122011300-A - Preparation method and application of dynamic covalent bond dual-curing 3D printing organic silicon resin

CN122011300ACN 122011300 ACN122011300 ACN 122011300ACN-122011300-A

Abstract

The invention relates to the technical field of 3D printing material manufacturing, and discloses a preparation method and application of dynamic covalent bond dual-curing 3D printing organic silicon resin, which comprises the steps of synthesizing organic silicon polyurethane acrylate prepolymer with a main chain containing hindered urea bonds, mixing the organosilicon polyurethane acrylate prepolymer, the reactive diluent, the micromolecular organosilicon thermosetting cross-linking agent and the photoinitiator to obtain resin, carrying out photo-curing printing to obtain a primary blank, and carrying out heat treatment on the primary blank to dissociate hindered urea bonds and carry out secondary cross-linking with the micromolecular organosilicon thermosetting cross-linking agent. The invention adopts a photo-thermal dual curing strategy, utilizes isocyanate groups generated by thermal dissociation of hindered urea bonds to react with a micromolecular organosilicon thermosetting cross-linking agent, so that a polymer network is evolved from an initial loose single structure to a high-crosslinking interpenetrating/hybridized network, interlayer defects are eliminated, crosslinking density is improved, and isotropic mechanical properties of the organosilicon elastomer are endowed.

Inventors

YU MIN
HAN XIAOYU
LIU LUCHUAN
DAI ZIQIANG
HE MINGHUI
HUANG YETING

Assignees

浙江科技大学

Dates

Publication Date: 20260512
Application Date: 20260309

Claims (10)

1. The preparation method of the dynamic covalent bond dual-curing 3D printing organic silicon resin is characterized by comprising the following steps of: S1, mixing an organosilicon polymer, diisocyanate and a catalyst, performing polymerization reaction under a heating condition to obtain an isocyanate group-terminated intermediate, and then adding a capping agent to perform capping reaction until the content of detected isocyanate groups reaches the standard to obtain an organosilicon polyurethane acrylate prepolymer; S2, taking the organosilicon polyurethane acrylate prepolymer, the reactive diluent, the micromolecular organosilicon thermosetting cross-linking agent and the photoinitiator, uniformly mixing and defoaming under the light-shielding condition to obtain the dynamic covalent bond dual-curing 3D printing organosilicon resin; S3, injecting the dynamic covalent bond dual-curing 3D printing organic silicon resin into a 3D printer, and performing layer-by-layer photo-curing according to model data to obtain a photo-curing organic silicon elastomer primary blank; S4, carrying out constant-temperature heat treatment on the light-cured organosilicon elastomer primary blank at a high temperature to enable dynamic covalent bond dissociation to occur in the primary blank, and completing secondary crosslinking reaction with the micromolecular organosilicon thermosetting crosslinking agent, and cooling to obtain the dynamic covalent bond dual-curing 3D printing organosilicon resin.
2. The method for preparing the dynamic covalent bond dual-curing 3D printing organic silicon resin according to claim 1, wherein in the step S1, the organic silicon polymer is silicon-terminated hydroxyl polydimethylsiloxane or amino-terminated propyl polydimethylsiloxane, and the polymerization degree n is an integer of 0-200; The diisocyanate is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate; The end capping agent is selected from one or more of 2- (tert-butylamino) ethyl methacrylate, hydroxyethyl acrylate and hydroxyethyl methacrylate.
3. The preparation method of the dynamic covalent bond dual-curing 3D printing organic silicon resin according to claim 1, wherein in the step S1, the specific process of the polymerization reaction is that the temperature is firstly increased to 50-60 ℃ for 1.5-2 hours, and then the temperature is increased to 80-85 ℃ for 2-3 hours; The specific method of the end capping reaction is that the reaction system is cooled to 50-55 ℃, the end capping agent is dripped, the temperature is raised to 65-75 ℃ after the dripping is finished, and the reaction is carried out for 3-4 hours until the isocyanate content is lower than 0.1%.
4. The method for preparing the dynamic covalent bond dual-curing 3D printing organic silicon resin according to claim 1, wherein in the step S2, raw materials for preparing the dynamic covalent bond dual-curing 3D printing organic silicon resin comprise the following raw materials in parts by weight: 100 parts of organosilicon polyurethane acrylate prepolymer; 20-50 parts of reactive diluent; 1-10 parts of small molecular organic silicon thermosetting cross-linking agent; 0.8-1.8 parts of photoinitiator.
5. The method for preparing the dynamic covalent bond dual-curing 3D printing organic silicon resin according to claim 1, wherein in the step S2, the reactive diluent is selected from one or more of isobornyl acrylate, hydroxyethyl methacrylate, 4-acryloylmorpholine, N-vinyl pyrrolidone, 1, 6-hexanediol diacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, tricyclodecane dimethanol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate and dipentaerythritol hexaacrylate.
6. The method for preparing the dynamic covalent bond dual-curing 3D printing organic silicon resin according to claim 1, wherein in the step S2, the small molecule organic silicon thermosetting cross-linking agent is selected from one or more of 1, 3-tetramethyl-1, 3-disilanol, 1, 3-bis (3-aminopropyl) tetramethyl disiloxane, hydroxyalkyl modified polysiloxane and small molecule chain extender containing hydroxyl or amino.
7. The method for preparing the dynamic covalent bond dual-curing 3D printing organic silicon resin according to claim 1, wherein in the step S3, the 3D printer is a digital light processing 3D printer, the printing parameters are set to be the printing layer thickness of 0.05-0.1 mm, the single-layer exposure time is 1.5-4 seconds, the light source wavelength is 405 nanometers, and the surface is cleaned by using absolute ethyl alcohol after printing is finished.
8. The method for preparing the dynamic covalent bond dual-curing 3D printing organic silicon resin according to claim 1, wherein in the step S4, the constant temperature heat treatment temperature is 90-110 ℃, and the treatment time is 3-5 hours.
9. The method for preparing a dynamic covalent bond dual-curing 3D printed silicone resin according to claim 1, wherein the main chain of the silicone polyurethane acrylate prepolymer contains a hindered urea bond, and in the step S4, the hindered urea bond is dissociated under heating to generate an isocyanate group, and the isocyanate group reacts with a hydroxyl group or an amino group in the small molecule silicone thermosetting cross-linking agent.
10. The use of a dynamic covalent bond dual cure 3D printed silicone resin, characterized in that the use of a dynamic covalent bond dual cure 3D printed silicone resin according to any one of claims 1-9 in the preparation of a silicone elastomer.

Description

Preparation method and application of dynamic covalent bond dual-curing 3D printing organic silicon resin Technical Field The invention relates to the technical field of 3D printing material manufacturing, in particular to a preparation method and application of a dynamic covalent bond dual-curing 3D printing organic silicon resin. Background The organosilicon elastomer is applied to the fields of flexible electronic devices, biomedical implants and soft robots by virtue of biocompatibility, high and low temperature resistance and excellent flexibility, and the digital light processing 3D printing technology can rapidly manufacture an organosilicon elastomer structure with a complex geometric shape by utilizing liquid photosensitive resin, so that the defect that a complex internal flow channel and a lattice structure are difficult to process in the traditional molding or pouring process is overcome. The existing photocuring 3D printing organosilicon technology mainly relies on free radical photopolymerization reaction of acrylic acid-based organosilicon prepolymer for molding, ultraviolet light initiates liquid resin to undergo rapid crosslinking curing in a layer-by-layer printing process to form a three-dimensional network structure, the double bond conversion rate of the surface of a cured layer is high due to the rapid rate of the free radical polymerization reaction, residual active reaction sites are fewer, a newly deposited liquid resin layer is difficult to form compact chemical bond connection with the surface of the cured layer, and the layers are mainly connected with each other by physical stacking or weak chemical bonding, so that the tensile strength and tear resistance of the photocuring 3D printing organosilicon elastomer in the stacking direction of the layers are lower than those of the plane direction, the anisotropy of the output mechanical properties is represented, and the service life and reliability of the photocuring 3D printing organosilicon elastomer serving as a stressed structural member are limited. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a preparation method and application of a dynamic covalent bond dual-curing 3D printing organic silicon resin, and solves the problems of weak interlayer bonding force, insufficient mechanical strength and anisotropy of a photo-curing 3D printing organic silicon material in the prior art. In order to achieve the above purpose, the invention is realized by the following technical scheme: the first aspect of the invention provides a preparation method of a dynamic covalent bond dual-curing 3D printing organic silicon resin, which comprises the following steps: S1, mixing an organosilicon polymer, diisocyanate and a catalyst, performing polymerization reaction under a heating condition to obtain an isocyanate group-terminated intermediate, and then adding a capping agent to perform capping reaction until the content of detected isocyanate groups reaches the standard to obtain an organosilicon polyurethane acrylate prepolymer; S2, taking an organosilicon polyurethane acrylate prepolymer, a reactive diluent, a micromolecular organosilicon thermosetting cross-linking agent and a photoinitiator, uniformly mixing and defoaming under a light-shielding condition to obtain dynamic covalent bond dual-curing 3D printing organosilicon resin; s3, injecting the dynamic covalent bond dual-curing 3D printing organic silicon resin into a 3D printer, and performing layer-by-layer photo-curing according to model data to obtain a photo-curing organic silicon elastomer primary blank; S4, carrying out constant-temperature heat treatment on the light-cured organosilicon elastomer primary blank at a high temperature to enable dynamic covalent bond dissociation to occur in the light-cured organosilicon elastomer primary blank, and completing secondary crosslinking reaction with the micromolecular organosilicon thermosetting crosslinking agent, and cooling to obtain the dynamic covalent bond dual-cured 3D printing organosilicon elastomer. By adopting the technical scheme, the preparation method of the dynamic covalent bond dual-curing 3D printing organic silicon resin utilizes a light curing and heat curing synergistic mechanism. First, in step S1, isocyanate reacts with a blocking agent, and a hindered urea bond and acrylate are introduced into the backbone of the silicone polyurethane prepolymer, giving the silicone polyurethane a photocurable group. And secondly, in the step S3, in the photo-curing stage, ultraviolet light initiates acrylate double bond free radical polymerization, and a preliminary cross-linking network is constructed, so that a photo-curing organosilicon elastomer primary blank is formed. Finally, in the S4 step heat treatment stage, the hindered urea bond is subjected to reverse dissociation reaction under the heating condition to generate isocyanate groups and amino groups, and the generated isocyana