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CN-121975078-A - Photo-curing polyurethane composition for 3D printing and application method thereof

CN121975078ACN 121975078 ACN121975078 ACN 121975078ACN-121975078-A

Abstract

The application discloses a photocuring polyurethane composition for 3D printing and a use method thereof, wherein the photocuring polyurethane composition comprises an isocyanate prepolymer, a polyol, a photobase generator and a reaction inhibitor, wherein the molar ratio of the isocyanate group of the isocyanate prepolymer to the hydroxyl group of the polyol is 1:0.8-1.2, the dosage of the photobase generator is 0.5% -5% and the dosage of the reaction inhibitor is 0.5% -3% based on the mass of the isocyanate prepolymer. The photocuring polyurethane composition for 3D printing disclosed by the application is single in component, stable in dark state and capable of being cured by illumination without pre-modification, can be seamlessly compatible with 3D printing equipment, and simultaneously can be used for obtaining the structural advantage of a polyurethane network in a three-dimensional real object.

Inventors

  • WU JINGJUN
  • XIE TAO
  • CHEN JIADA
  • ZHAO JIAN

Assignees

  • 浙江大学

Dates

Publication Date
20260505
Application Date
20260213

Claims (10)

  1. 1. The photocuring polyurethane composition for 3D printing is characterized by comprising an isocyanate prepolymer, a polyol, a photobase generator and a reaction inhibitor, wherein the molar ratio of isocyanate groups of the isocyanate prepolymer to hydroxyl groups of the polyol is 1:0.8-1.2, the dosage of the photobase generator is 0.5% -5% and the dosage of the reaction inhibitor is 0.5% -3% based on the mass of the isocyanate prepolymer.
  2. 2. The photocurable polyurethane composition for 3D printing according to claim 1, wherein the NCO value of the isocyanate prepolymer is 3% -8%.
  3. 3. The photocurable polyurethane composition for 3D printing according to claim 1, wherein the polyol has a molecular weight of greater than 60, a functionality of2 or greater, and a mole fraction of polyol having a functionality of greater than 2 of greater than 20%.
  4. 4. The photocurable polyurethane composition for 3D printing of claim 1, wherein the photobase generator is at least one of a urethane photobase generator, an oxime ester photobase generator, and an ammonium salt photobase generator.
  5. 5. The photocurable polyurethane composition for 3D printing according to claim 1, wherein the photobase generator is thioxanthone derivative TxAA-DBU or coumarin-based derivative NPPOC-TMG.
  6. 6. The photocurable polyurethane composition for 3D printing according to claim 1, wherein the reaction inhibitor is at least one of a small molecule acid, a carboxyl group-containing polyol, a sulfonate group-containing polyol.
  7. 7. A method of using the photocurable polyurethane composition for 3D printing as recited in any one of claims 1-6, comprising: step 1, printing layer by using the photo-curing polyurethane composition as a raw material and performing photo-curing by using 3D printing equipment to obtain an initial three-dimensional entity; Step 2, cleaning and supporting the initial three-dimensional entity, and performing secondary photo-curing to obtain the three-dimensional entity; And 3, performing heat treatment on the three-dimensional entity to obtain the three-dimensional entity.
  8. 8. The method of using a photocurable polyurethane composition for 3D printing as recited in claim 7, wherein in step 1, the intensity of the light for photocuring is 2-8 mw/cm 2 , and the layer thickness is 0.03-0.25 mm.
  9. 9. The method of using a photocurable polyurethane composition for 3D printing as recited in claim 7, wherein in step 2, the secondary photocuring illumination intensity is 50-200mW/cm 2 and the irradiation time is 30s-90s.
  10. 10. The method of using a photocurable polyurethane composition for 3D printing as recited in claim 7, wherein in step 3, the heat treatment is performed at a temperature of 40-60 ℃ for a time of 0.5-2 hours.

Description

Photo-curing polyurethane composition for 3D printing and application method thereof Technical Field The application relates to the technical field of 3D printing, in particular to a photo-curing polyurethane composition for 3D printing and a using method thereof. Background Photocuring 3D printing techniques (such as stereolithography SLA and digital light processing DLP) are widely used in rapid prototyping, customized products and functional part production fields by virtue of high precision, high efficiency and excellent surface quality. As a core material of the technology, the performance of the photosensitive resin directly determines the applicable scene of the final product, and the polymerization reaction of the photo-curing printing usually takes an acrylic ester double bond as a reaction site, and the polymerization is realized by free radical initiation. The polyurethane material has high designability due to the molecular structure, has excellent wear resistance, high elasticity, impact resistance, low-temperature toughness and biocompatibility, and occupies an irreplaceable position in the fields of shoe materials, automobile interiors, medical catheters, flexible electronic packaging and the like. The micro-phase separation structure of the soft and hard segments can realize continuous regulation and control of the performance from the soft elastomer to the hard engineering plastic, and part of polyurethane systems have self-repairing and recyclable properties endowed by dynamic bonds (such as urea bonds and urethane bonds). However, the traditional polyurethane curing depends on thermal initiation or moisture curing, has the problems of slow reaction rate and low precision, and is difficult to meet the core requirements of photo-curing 3D printing on 'space selectivity, second-level curing and interlayer precise combination'. To introduce the excellent properties of polyurethane into the field of photo-curing 3D printing, the prior art has mainly employed an "acrylate capping" strategy, in which polyurethane acrylates (PUA) are produced by reacting the isocyanate groups of polyurethane prepolymers with acrylate capping agents. The Chinese patent document CN119119419B, CN118725211A adopts a route of firstly synthesizing polyurethane prepolymer with end groups of isocyanate and then reacting the polyurethane prepolymer with hydroxy acrylic ester to prepare the photo-curable polyurethane acrylic ester. However, the modification method needs to add an extra synthesis step, the network main body formed after the curing is polyacrylate, the polyurethane chain segment only plays a role of flexible interval, the specific hydrogen bond network, microphase separation structure and dynamic performance of the polyurethane chain segment are obviously weakened, and the intrinsic advantage of the polyurethane is difficult to fully develop. In order to further merge the dynamic characteristics and photocuring efficiency of polyurethane, recent research has focused on a "dynamic chemistry+photocuring" compounding strategy. Chinese patent document CN115195104B discloses polyurethane acrylic ester blocked by a blocked urea bond, which is subjected to heat treatment after photo-curing molding, wherein the blocked urea bond can be dissociated and recombined to form a polyurethane/polyacrylate interpenetrating network (IPN) so as to endow a product with thermal remodeling capability, and Chinese patent document CN113307941B utilizes the reaction of ethylene glycol methyl methacrylate and isocyanate to construct a reversible dynamic bond, so that a photo-curing material with lower water absorption rate and glass transition temperature after heat treatment is developed. However, the technology still needs to synthesize the acrylated polyurethane in advance, and meanwhile, the subsequent heat treatment step increases the complexity of the process, and the heat treatment process is easy to cause the deformation of the microstructure, so that the dimensional stability of the high-precision component is affected. Notably, chinese patent CN115772379B discloses a UV-retarded cure two-component polyurethane adhesive that utilizes photobase generators (e.g., salts) to release organic bases (e.g., DBU) under 365nm light, catalyzing isocyanate and polyol reactions in situ to form polyurethane. The technology realizes 'light-triggered polyurethane synthesis', but adopts strict two-component design that the component A contains isocyanate prepolymer and photo-alkaline agent, and the component B contains polyol and catalyst, and the components are mixed on site before use. The design has three major bottlenecks of (1) short pot life (usually less than 30 minutes) after mixing, and can not meet the requirement of long-term stable feeding of the 3D printing resin tank, (2) the two-component system needs to reform printing equipment (additionally provided with a double-material path and a mixing head), is completely incompatible