Dual cure additive manufacturing resins for production of flame retardant objects

A method of forming a three-dimensional object, comprising:

• (a) providing a polymerizable liquid comprising a mixture of (i) a light polymerizable first component, (ii) a second solidifiable component that is different from said first component, wherein said second solidifiable component comprises a flame retardant group, said flame retardant group comprising a halogen group, and (iii) a flame retardant synergist, said flame retardant synergist comprising antimony pentoxide, wherein said antimony pentoxide is functionalized with ethoxylated amine;
• (b) producing a three-dimensional intermediate from said polymerizable liquid by stereolithography including irradiating said polymerizable liquid with light to form a solid polymer scaffold from said first component and containing said second solidifiable component carried in said scaffold, said intermediate having the same shape as, or a shape to be imparted to, said three-dimensional object;
• optionally wherein said polymerizable liquid further comprises an organic diluent and where said irradiating is performed under conditions in which said organic diluent chemically reacts by an amount sufficient to increase the strength of said intermediate;
• (c) optionally washing said intermediate, and
• (d) concurrently with or subsequent to said producing step (b), further curing said second solidifiable component in said three-dimensional intermediate to form said three-dimensional object.