US 11,655,329 B2
Delayed action catalysts for dual cure additive manufacturing resins
Andrew Gordon Wright, Mountain View, CA (US)
Assigned to Carbon, Inc., Redwood City, CA (US)
Filed by Carbon, Inc., Redwood City, CA (US)
Filed on Apr. 19, 2021, as Appl. No. 17/234,019.
Claims priority of provisional application 63/014,908, filed on Apr. 24, 2020.
Prior Publication US 2021/0332178 A1, Oct. 28, 2021
Int. Cl. C08F 2/46 (2006.01); C08F 2/50 (2006.01); C08G 61/04 (2006.01); C08G 18/48 (2006.01); C08G 18/16 (2006.01); C08G 18/73 (2006.01); B33Y 70/00 (2020.01)
CPC C08G 18/482 (2013.01) [B33Y 70/00 (2014.12); C08G 18/168 (2013.01); C08G 18/73 (2013.01)] 16 Claims
 
1. A method of making an object, comprising:
(a) providing a dual cure resin comprising:
(i) a photoinitiator;
(ii) not more than 20 ppm of a polyurethane catalyst;
(iii) a polyol;
(iv) free polyisocyanate; and
(v) blocked polyisocyanate, the isocyanate groups of which are blocked by reaction with an amine (meth)acrylate blocking agent wherein the molar ratio of free polyisocyanate to blocked polyisocyanate in said dual cure resin is at least 1 to 1;
(b) producing an intermediate object by light polymerization of said resin in an additive manufacturing process;
(c) optionally cleaning said intermediate object; and then
(d) heating said intermediate object, wherein said amine (meth)acrylate blocking agent is present in said resin as a blocking agent in an amount sufficient so that, upon forming the intermediate object from said resin by light polymerization in the additive manufacturing process and subsequent heating of said intermediate object, said blocked polyisocyanate de-blocks and produces free amine (meth)acrylate in an amount effective to catalyze the polymerization of at least said free polyisocyanate with said polyol, and produce said object.