Epoxy Based Blends for Additive Manufacturing by Liquid Crystal Display (LCD) Printing: The Effect of Blending and Dual Curing on Daylight Curable Resins

Abstract

Epoxy-based blends printable in a Liquid Crystal Display (LCD) printer were studied. Diglycidyl ether of bisphenol A (DGEBA) mixed with Diethyltoluene diamine (DETDA) was used due to the easy processing in liquid form at room temperature and slower reactivity until heated over 150 ° C. The DGEBA/DETDA resin was mixed with a commercial daylight photocurable resin used for LCD screen 3D printing. Calorimetric, dynamic mechanical and rheology testing were carried out on the resulting blends. The daylight resins showed to be thermally curable. Resin’s processability in the LCD printer was evaluated for all the blends by rheology and by 3D printing trials. The best printing conditions were determined by a speed cure test. The use of a thermal post-curing cycle after the standard photocuring in the LCD printer enhanced the glass transition temperature T g of the daylight resin from 45 to 137 ° C when post-curing temperatures up to 180 ° C were used. The T g reached a value of 174 ° C mixing 50 wt% of DGEBA/DETDA resin with the photocurable resin when high temperature cure cycle was used.

Photopolymerization-based additive manufacturing of ceramics: A systematic review

“…LCD is one of the latest and much affordable photopolymerization-based AM techniques with a bottom-up printing system [162]. The approach is similar to the DLP and SL but with different imaging system [162,163]. Specifically, LCD uses liquid crystal display for the imaging of the polymer resins [9].…”

Liquid Crystal Display (LCD) Printing: A Novel System for Polymer Hybrids Printing

“…By setting the right value for the exposure time parameter all the parts were printed with good results. The exposure time of 10 s is lower than the values found previously for LHR2 printer which ranged between 25 and 30 s. [ 9 ] This result is important in view of the use of more complex tough resins as base for optimized formulations. [ 10,11 ]…”

“…A T g increment of about 14% was observed by subjecting the LCD printed to a thermal post‐curing process at 80 °C for 2 h. A similar behavior was identified by following the same procedure on the daylight resin Cream Hard due to crosslink density increases. [ 9 ]…”

“…[ 13,14 ] The daylight resins contain (meth)acrylates oligomers and monomers that can be cured by photopolymerization and by heat. [ 9 ]…”

State-of-the-Art Polymer Science and Technology in Italy

“…A new formulation based on Diglycidyl ether of bisphenol A (DGEBA) mixed with Diethyltoluene diamine (DETDA) and with a commercial daylight photocurable resin was prepared by Tosto et al to obtain printable materials in a liquid crystal display (LCD) 3D printer. After the calorimetric, dynamic mechanical and rheology testing, the authors carried out 3D printing trials, thus determining the best printing conditions [23].…”