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

1 . A radiation curable composition for additive fabrication with improved toughness comprising:

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 is greater than 130 g/mol.

2 . The radiation curable composition for additive fabrication with improved toughness of claim 1 , wherein the liquid phase-separating toughening agent is a high molecular weight dimer fatty acid polyol.

3 . The radiation curable composition for additive fabrication with improved toughness of claim 1 , wherein the high molecular weight 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.

4 . The radiation curable composition for additive fabrication with improved toughness of claim 1 , wherein the high molecular weight dimer fatty acid polyol possesses a molecular weight of greater than 8000 g/mol.

5 . The radiation curable composition for additive fabrication with improved toughness of claim 4 , wherein the high molecular weight dimer fatty acid polyol is a propylene oxide or ethylene oxide.

6 . The radiation curable composition for additive fabrication with improved toughness of claim 1 , wherein M C of the rubber toughenable base resin is less than 500 g/mol.

7 . The radiation curable composition for additive fabrication with improved toughness of claim 6 , wherein a three-dimensional component created therefrom by means of an additive fabrication process yields an elongation value that is at least 50% greater than a corresponding elongation value of a three dimensional component created from the constituent rubber toughenable base resin of said radiation curable composition.

8 . The radiation curable composition for additive fabrication with improved toughness of claim 7 , wherein a three-dimensional component created therefrom by means of an additive fabrication process yields an HDT value that is within at least 5 degrees Celsius of a corresponding elongation value of a three dimensional component created from the constituent rubber toughenable base resin of said radiation curable composition.

9 . A radiation curable composition for additive fabrication with improved toughness comprising:

a rubber toughenable base resin further comprising

(1) optionally, a cationically polymerizable component;

(2) a radically polymerizable component;

(3) optionally, a cationic photoinitiator;

(4) a free radical photoinitiator; and

(5) optionally, customary additives; and

a liquid phase-separating toughening agent;

wherein the liquid phase-separating toughening agent is an epoxidized pre-reacted hydrophobic macromolecule;

wherein the average molecular weight between crosslinks (M C ) of the rubber toughenable base resin is greater than 180 g/mol; and

wherein the M C of the rubber toughenable base resin is less than 260 g/mol.

10 . The radiation curable composition for additive fabrication with improved toughness of claim 9 , wherein the rubber toughenable base resin further contains, relative to the entire weight of the rubber toughenable base resin, of

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

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

11 . The radiation curable composition for additive fabrication with improved toughness of claim 10 , 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.

12 . The radiation curable composition for additive fabrication with improved toughness of claim 11 , 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.

13 . The radiation curable composition for additive fabrication with improved toughness of claim 12 , wherein the soft-block originator is selected from the group consisting of polybutadienes, polyols, and polydmethylsiloxanes, and any combination thereof.

14 . The radiation curable composition for additive fabrication with improved toughness of claim 9 , wherein the epoxidized pre-reacted hydrophobic macromolecule is derived from a triglyceride fatty acid.

15 . The radiation curable composition for additive fabrication with improved toughness of claim 9 , wherein the epoxidized pre-reacted hydrophobic macromolecule is derived from a tall oil, wherein the epoxidized tall oil is an epoxidized vegetable oil, such as soybean or linseed oil.

16 . The radiation curable composition for additive fabrication with improved toughness of claim 9 , 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.

17 . The radiation curable composition for additive fabrication with improved toughness of claim 9 , wherein the epoxidized pre-reacted hydrophobic macromolecule possesses a molecular weight of from about 800 g/mol to about 4000 g/mol.

18 . The radiation curable composition for additive fabrication with improved toughness of claim 17 , 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%, more preferably from about 1.5% to about 12%.

19 . A process of forming a three-dimensional object comprising the steps of forming and selectively curing a liquid layer of the radiation curable composition for additive fabrication with improved toughness of any one of claims 1 - 18 with actinic radiation and repeating the steps of forming and selectively curing the liquid layer of the radiation curable composition for additive fabrication of any one of claims 1 - 18 a plurality of times to obtain a three-dimensional object.

20 . (canceled)