3D printing set and method for 3D inkjet printing by using the same

A method for 3D inkjet printing, comprising:

• a preheating step:
• using an external heating source to heat a main body layer composed of a first composition to a first temperature, wherein the main body layer has a thickness of 10 μm to 500 μm and a unit density of 0.1 to 1.0 g/cm3, and the first temperature is less than the melting point of the first composition;
• a heating step:
• applying a second composition to the surface of the main body layer at the first temperature to proceed an exothermic cross-linking polymerization, so that the main body layer is heated to a second temperature to become a molten state, wherein the second temperature is greater than the melting point of the first composition;
• and
• a cooling step:
• cooling down the main body layer in the molten state and solidifying to form;
• wherein the first composition comprises at least a compound A, a compound B or a polyamine compound, in which the compound A is a polyamide selected from the group consisting of a semi-crystalline polyamide, preferably polyamide-6 (PA-6), polyamide-66 (PA-66), polyamide-610 (PA-610), polyamide-1010 (PA-1010), polyamide-11 (PA-11), polyamide-12 (PA-12), polyamide-9 (PA-9), polyamide-612 (PA-612), polyamide-121 (PA-121), polyphthalamide (PPA), and polyparaphenylene terephthalamide (PPTA), the compound B is a polyurethane selected from the group consisting of polyurethane (PU), and thermoplastic polyurethane (TPU);
• the polyamine compound is selected from the group consisting of ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, diethylenetriamine, 1,2-propanediamine, 1,4-diazacycloheptane, and phenylenediamine;
• the second composition comprises at least a compound C selected from the group consisting of toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenyl methane diisocyanate (MDI), dicyclohexylmethane diisocyanate (H12MDI), lysine diisocyanate (LDI), HDI polyisocyanates, 1,3,5-triazine-2,4,6(1H,3H,5H)-trione), 1,3,5-tris(6-isocyanatohexyl), 1,3,5-tris(6-hydroxyhexyl)biuret triisocyanate, potassium cyanate, sodium hydrogenate, and ammonium cyanate, and a weight ratio of the molding material in the main body layer to the compound C is in a range of between 1:1 to 10:1;
• the printing method uses the heat of chemical reaction between the first composition and the second composition as a part of a heat source for melting the main body layer, thereby reducing the heat of the external heating source.