RADIATION CURABLE COMPOSITIONS FOR ADDITIVE FABRICATION WITH IMPROVED TOUGHNESS AND HIGH TEMPERATURE RESISTANCE

1 .- 20 . (canceled)

21 . A process of forming a three-dimensional object comprising the steps of forming a liquid layer of the radiation curable composition for additive fabrication; selectively curing said liquid layer of the radiation curable composition with actinic radiation; and repeating the steps of forming and selectively curing the liquid layer of the radiation curable composition for additive fabrication a plurality of times to obtain a three-dimensional object; wherein the radiation curable composition comprises:

a rubber toughenable base resin further comprising

a cationically polymerizable component;

a radically polymerizable component;

a cationic photoinitiator;

a free radical photoinitiator; and

optionally, customary additives; and

a liquid phase-separating toughening agent;

wherein the liquid phase-separating toughening agent is present in an amount, relative to the weight of the rubber toughenable base resin, in a ratio from 1:99 to about 1:9; and

wherein the average molecular weight between crosslinks (M C ) of the rubber toughenable base resin between 150 and 500 g/mol; and

wherein the three-dimensional object possesses an elongation-at-break (EAB) value of at least 5%, and a heat deflection temperature (HDT) value of at least 75 degrees Celsius (° C.).

22 . The process of claim 21 , wherein the three-dimensional object possesses an EAB value from 10% to 50%, and an HDT value of greater than 85° C.

23 . The process of claim 22 , wherein the liquid phase-separating toughening agent comprises a high molecular weight dimer fatty acid polyol.

24 . The process of claim 22 , wherein the high molecular weight dimer fatty acid polyol is selected to be configured to form, after curing of the radiation curable composition, phase domains with an average size of from about 2 microns to about 25 microns, when measured according to an Average Phase Domain Size Procedure.

25 . The process of claim 24 , wherein the high molecular weight dimer fatty acid polyol is a propylene or ethylene oxide which possesses a molecular weight of greater than 8000 g/mol.

26 . The process of claim 22 , wherein the M C of the rubber toughenable base resin is between 180 and 260 g/mol.

27 . The process of claim 26 , wherein the three-dimensional object possesses an elongation value of at least 15%.

28 . The process of claim 22 , wherein the liquid phase-separating toughening agent comprises an epoxidized pre-reacted hydrophobic macromolecule.

29 . The process of claim 28 , wherein the rubber toughenable base resin further contains, relative to the entire weight of the rubber toughenable base resin,

less than about 40 wt. % of at least one aromatic glycidyl epoxy, and

at least about 5 wt. % of a polyol component.

30 . The process of claim 28 , wherein the epoxidized pre-reacted hydrophobic macromolecule is a triblock copolymer possessing

terminating epoxy- or acrylate-functional hard blocks; and

at least one immiscible soft block.

31 . The process of claim 30 , wherein the triblock copolymer is formed by the reaction product of

a soft-block originator with

a monofunctional anhydride such as hexahydrophthalic anhydride,

and then further reacting an epoxy-functional reactant.

32 . The process of claim 31 , wherein the soft-block originator comprises polybutadienes, polyols, polydimethylsiloxanes, or combinations thereof.

33 . The process of claim 28 , wherein the epoxidized pre-reacted hydrophobic macromolecule is derived from a triglyceride fatty acid.

34 . The process of claim 28 , wherein the epoxidized pre-reacted hydrophobic macromolecule comprises the reaction product of a tall oil.

35 . The process of claim 34 , wherein the tall oil comprises soybean oil or linseed oil.

36 . The process of claim 28 , wherein the epoxidized pre-reacted hydrophobic macromolecule is derived from a compound of the following formula:

wherein R 1 , R 2 , and R 3 are the same or different, and are each a C 4 -C 50 unsaturated alkyl chain, wherein the unsaturation has been at least 30% epoxidized.

37 . The process of claim 28 , wherein the epoxidized pre-reacted hydrophobic macromolecule possesses a molecular weight from 800 g/mol to about 4000 g/mol.

38 . The process of claim 28 , wherein the epoxidized pre-reacted hydrophobic macromolecule is present, relative to the weight of the entire composition, in an amount from about 1% to about 20%.

39 . The process of claim 38 , wherein the liquid phase-separating toughening agent is present in an amount, relative to the weight of the rubber toughenable base resin, in a ratio from 1:50 to 1:12.

40 . The process of claim 38 , wherein the epoxidized pre-reacted hydrophobic macromolecule is present, relative to the weight of the entire composition, in an amount from 1.5% to 12%, and the three-dimensional object possesses an HDT value of at least 95° C.