Substrate-based additive fabrication process and apparatus

1. A process for additive fabrication comprising:

(1) providing a flexible multi-layer substrate comprising a transport layer and a structural layer, the transport layer comprising a polyolefin or a fluoropolymer, and the structural layer comprising a semi-crystalline thermoplastic polymer;

(2) coating a layer of radiation curable resin on the transport layer of the flexible multilayer substrate;

(3) contacting the layer of radiation curable resin with a previously cured layer;

(4) exposing the layer of radiation curable resin to actinic radiation, provided by a source of actinic radiation, thereby forming a cured layer which adheres to the previously cured layer;

(5) separating the cured layer and the flexible multi-layer substrate; and

(6) repeating steps 2-5 a sufficient number of times in order to build up a three-dimensional object;

wherein the flexible multi-layer substrate has either a specific essetial work of fracture greater than 12 kJ/m 2 and less than 500 kJ/m 2 , a w p β of greater than 8 mJ/mm 3 and less than 500 mJ/mm 3 , or both, in each direction of support.

2. The process of claim 1 wherein the flexible multi-layer substrate possesses a parallel direction and a transverse direction and the flexible multi-layer substrate has either a specific essential work of fracture of greater than 12 kJ/m 2 and less than 500 kJ/m 2 , a w p β of greater than 8 mJ/mm 3 and less than 500 mJ/mm 3 , or both, in both the parallel direction and the transverse direction.

3. The process of claim 1 wherein the radiation curable resin comprises from 30 to 85 wt. % of cationically curable compounds, and from 10 to 60 wt. % of free-radically curable compounds.

4. The process of claim 1 wherein the transport layer possesses a surface, said surface being secured to the structural layer, wherein at least a portion of said surface has been subject to a corona treatment.

5. The process of claim 1 wherein the flexible multi-layer substrate has a thickness of from 20 to 250 microns.

6. The process of claim 1 wherein the actinic radiation is UV radiation in the range from 320 to 400 nm.

7. The process of claim 1 wherein the transport layer comprises a polyolefin.

8. The process of claim 1 wherein the transport layer is a polyethylene or polymethylpentene.

9. The process of claim 1 wherein the structural layer is a thermoplastic polyamide or thermoplastic polyester.

10. The process of claim 1 wherein the radiation curable resin possesses a temperature from 25 degrees C. to 45 degrees C. at the time of exposure to the actinic radiation.

11. The process of claim 1 wherein the transport layer has a matte surface finish.

12. The process of claim 1 wherein flexible multi-layer substrate is a two-layer substrate created by a lamination process, the transport layer and structural layer being secured to one another with a polyurethane adhesive.

13. A process for additive fabrication comprising:

(1) coating a layer of radiation curable resin on a substrate, said substrate having a parallel direction and a transverse direction, and a surface tension of from 19.5 mN·m −1 to 41 nN·m −1 , a specific essential work of fracture from 12 kJ/m 2 to 500 kJ/m 2 in both the parallel direction and the transverse direction, a tensile modulus at the operating temperature of the additive fabrication process above 0.2 GPa and less than 6 GPa in the parallel direction, and a yield stress above 20 MPa and less than 150 MPa in the parallel direction;

(2) contacting the layer of radiation curable resin with a previously cured layer;

(3) exposing the layer of radiation curable resin to actinic radiation, provided by a source of actinic radiation, thereby forming a cured layer which adheres to the previously cured layer;

(4) separating the cured layer and the substrate; and

(5) repeating steps 1-4 a sufficient number of times in order to build up a three-dimensional object.

14. The process of claim 13 wherein the substrate is a flexible multi-layer substrate comprising a transport layer and a structural layer and the layer of radiation curable resin is coated on the transport layer of the multi-layer substrate.

15. The process of claim 13 wherein the actinic radiation is light, said light possessing a transmission spectrum, and wherein the substrate has a transmission of 80% of the light at the transmission spectrum.

16. The process of claim 13 wherein the substrate possesses a T g of from 30° C. to about 200° C.

17. The process of claim 15 wherein the substrate possesses a T g of from 30° C. to about 65° C.

18. The process of claim 13 wherein the substrate possesses a w p β of greater than 8 mJ/mm 3 in both the parallel and transverse direction.

19. The process of claim 13 Wherein the operating temperature of the additive fabrication process is from 25° C. to 45° C.