Patent ID: 12194672

DESCRIPTION OF PREFERRED EMBODIMENTS

Example 1

FIG.1is a near-infrared light polymerized DIW 3D printing device, which is composed of a support table1, a near-infrared light emitting structure2, a controller3, a direct writing nozzle4, and an ink storage tank5.

The support table1is used to support three-dimensional objects6; the near-infrared light emitting structure2is located above the support table1, and is fixedly connected to the controller3. The controller3drives the near-infrared light emitting structure2to move or stand still; the direct writing nozzle4is located Above the supporting table1, the direct writing nozzle4and the ink storage tank5are hermetically connected, the direct writing nozzle4and the ink storage tank5are fixedly connected with the controller3, and the controller3drives the direct writing nozzle4and the ink storage tank5to move or stop.

Raw material 1.0 wt. % initiator (Irgacure 784), 1.0 wt. % NaYF4 up-conversion nanoparticles, 13.0 wt. % thixotropic agent (Aerosil, Evonik TS100), 42.5 wt. % epoxy acrylate resin and 42.5 wt. % monomer. After weighing the trimethylolpropane acrylate (TMPTA), it is fully mixed in the mixed defoamer to obtain the ink (the elastic modulus G′ is 0.53 kPa, and the loss modulus G″ is 0.28 kPa). Fill the ink into the ink storage tank, control the extrusion pressure to 50 kPA, the ink is extruded through the direct writing nozzle (0.21, 0.41, 0.80, 1.55, 2.50, 4.00 mm), and the direct writing nozzle is made in the horizontal plane through the controller. In reciprocating motion, the laser emitting structure and the direct writing nozzle are relatively static, and the beam is located 2 mm directly below the direct writing nozzle. The laser emitting structure emits a light beam with a wavelength of 980 nm, the laser power is 3.5 W, and the printing speed is controlled at 1.0 mm/s. Lines with different line widths can be obtained, as shown inFIG.2. The characteristic absorption peak changes are measured by total reflection Fourier transform infrared spectroscopy. No matter the line diameter is widened (0.41-4.00 mm), the conversion rate does not fluctuate significantly, at about 50%, which proves that the near-infrared penetration can achieve uniform curing.

Example 2

Real-time curing using near-infrared light using the same process parameters, direct writing printing equipment and working parameters of the ink in Example 1, only 0.41 mm nozzles are used for grid printing (first control the direct writing nozzles to reciprocate in the horizontal plane, and then control the direct writing nozzle lifted and changes the original direction of movement to continue reciprocating motion) to obtain a 3D printed object as shown in the right ofFIG.3.

For curing using near-infrared light after printing: using the same ink process parameters, direct writing printing equipment and working parameters mentioned above, using 0.41 mm nozzles for grid printing, the ink moves with the direct writing nozzles and is extruded to obtain the shape, After the extrusion is finished, the near-infrared light is used for curing to obtain a 3D printed object as shown in the left ofFIG.3.

A comparison is made between using near-infrared light to cure after printing and using near-infrared light to cure in real time, as shown inFIG.2. The lines of the post-cured sample collapsed, while the lines of the real-time cured sample remained better and the structure was regular.

Example 3

The working setup of the near-infrared photopolymerized ink direct-write 3D printing equipment is the same as in Example 1. The 1.0% wt initiator (Irgacure 784), 1.0 wt % NaYF4:Yb, Tm up-conversion nanoparticles, 0.5 wt. % colorant (red, Yellow, blue, white), 12.5 wt. % thixotropic agent (aerosol, Evonik TS100), 42.5 wt % epoxy acrylate resin and 42.5 wt. % monomer trimethylolpropane acrylate (TMPTA) after weighing In the mixed defoaming machine, the ink is obtained by fully mixing (the elastic modulus G′ is 0.49 kPa, and the loss modulus G″ is 0.25 kPa). Fill the ink into the printer, control the extrusion pressure to 50 kPA, use a 1.55 mm direct writing nozzle, the laser power is 3.5 W, and the printing speed is controlled to 1.0 mm/s. Lines of different colors can be obtained, and the result is shown inFIG.4. As shown inFIG.5, according to the ultraviolet-visible light absorption spectrum, the absorption band (300-500 nm) of the initiator used overlaps with the absorption peak of the color paste, and there is a competitive relationship in the process of absorbing and using the energy of the light source. If ultraviolet-blue light is used Printing curing is difficult to achieve curing. The characteristic absorption peak changes of samples after NIR curing were measured by total reflection Fourier transform infrared spectroscopy. The phase conversion rate of different colors did not fluctuate significantly, at about 40%, which proved that the color samples can be cured by using near-infrared penetration.

Example 4

Use coaxial nozzles (outside 1.3 mm, inside 0.5 mm) for simultaneous dual-color extrusion of the color paste in Example 3 under the same process: use coaxial nozzles (outside 1.3 mm, inside 0.5 mm) as direct writing nozzles, At the same time, the two-color inks are filled and connected to the inner and outer flow channels of the coaxial nozzle, and they are extruded under the force and are irradiated by the near-infrared to realize curing to obtain lines with two colors inside and outside. It is proved that it is possible to realize multi-color/multi-material by using near-infrared penetration, and the result is shown inFIG.6.

Example 5

Under the printing parameters in Example 3, by simultaneously raising the direct writing nozzle and the near-infrared light spot, the ink is gradually extruded from the substrate into the suspended air and solidified, so that 3D printing of a self-supporting suspended structure can be realized. Compared with traditional 3D printing methods, such as thermally cured ink direct writing, techniques such as stereo lithography need to add additional support to the suspended structure and cut after printing. The method utilizes the penetrability and controllability of near-infrared curing to promote the ink to reach the gel point quickly and uniformly to realize the self-supporting ability.