Silicone formulations for 3D printing
In one embodiment, a silicone-based ink for additive manufacturing includes a vinyl-terminated siloxane macromer, a hydrophobic reinforcing filler, and a rheology modifying additive. In another embodiment, a method of additive manufacturing with silicone-based ink includes adding a mixture that includes a vinyl-terminated siloxane macromer, a hydrophobic reinforcing filler, and a rheology modifying additive to a cartridge for additive manufacturing, extruding the mixture through the cartridge to form a structure, and curing the mixture to at least a predefined extent.
1. A silicone-based ink for extrusion of continuous filaments, the ink comprising:
a vinyl-terminated diphenyl siloxane macromer;
a treated silica hydrophobic reinforcing filler;
a rheology modifying additive selected from the group consisting of: a silicone polyether, glycerol, 2-propanol, and a combination thereof;
a curing agent;
an effective amount of an inhibitor for controlling a rate of curing by the curing agent;
a crosslinking agent, wherein the crosslinking agent is a hydride terminated copolymer; and
a crosslinking additive, wherein the crosslinking additive is a hydride chain extender, wherein the crosslinking additive and the crosslinking agent have different molecular structures from each other, wherein the crosslinking additive is configured to decrease a crosslinking density of the silicone-based ink.
2. The ink as recited in claim 1 , wherein the curing agent induces curing in response to catalyst-mediated hydrosilylation chemistry.
3. The ink as recited in claim 1 , wherein the curing agent induces curing in response to ultraviolet radiation.
4. The ink as recited in claim 1 , wherein the curing agent induces curing in response to free radical chemistry.
5. The ink as recited in claim 1 , wherein the vinyl-terminated diphenyl siloxane macromer has a viscosity in a range of about 500 centistoke and about 50,000 centistoke.
6. The ink as recited in claim 1 , wherein the treated silica hydrophobic reinforcing filler is a treated silica having capped silanol groups.
7. The ink as recited in claim 6 , wherein the treated silica has a surface area in a range of about 50 m 2 /g and about 250 m 2 /g.
8. The ink as recited in claim 6 , wherein the treated silica is hexamethyldisilazane-treated silica.
9. The ink as recited in claim 1 , wherein the rheology modifying additive is the silicone polyether.
10. The ink as recited in claim 1 , wherein the ink is a pseudoplastic, non-Newtonian fluid.
11. The ink as recited in claim 1 , wherein the treated silica has a surface area in a range of about 100 m 2 /g and about 200 m 2 /g.
12. The ink as recited in claim 1 , wherein the ink is stable without crystallinity at temperatures down to −150° C.
13. The ink as recited in claim 1 , wherein a concentration of the rheology modifying additive is in a range of about 0.2 wt % to about 1.0 wt % of total ink.
14. The ink as recited in claim 1 , wherein the treated silica hydrophobic reinforcing filler and the rheology modifying additive are different materials.
15. A method of additive manufacturing with silicone-based ink, the method comprising:
adding a first mixture to a cartridge for additive manufacturing, the first mixture comprising a vinyl-terminated diphenyl siloxane macromer, a treated silica hydrophobic reinforcing filler, and a rheology modifying additive;
extruding a continuous filament of the first mixture through the cartridge to form a first layer in an x-y plane;
depositing by extrusion of the continuous filament in the x-y plane each of a plurality of subsequent layers above the first layer in a z-direction perpendicular to the x-y plane, wherein the continuous filament forms a three dimensional structure having the plurality of layers; and
after forming the entire structure having the plurality of layers, curing the mixture to at least a predefined extent.
16. The method as recited in claim 15 , further comprising adding to the mixture in the cartridge, a curing agent and a crosslinking agent.
17. The method as recited in claim 16 , further comprising adding to the mixture, in the cartridge, an effective amount of an inhibitor for controlling a rate of curing by the curing agent.
18. The method as recited in claim 15 , wherein a portion of at least one layer is formed from a second mixture, wherein a crosslinking density of the second mixture and a crosslinking density of the first mixture are different.
19. A product of extrusion-based printing with a silicone-based ink, the product comprising:
an uncured three-dimensional structure comprising a continuous filament of a first material comprising a vinyl-terminated diphenyl siloxane macromer, a hydrophobic reinforcing filler, and a rheology modifying additive,
wherein the continuous filament forms each of a plurality of layers,
wherein each of the plurality of layers is deposited in a layer-by-layer pattern during the printing,
wherein the plurality of layers are arranged in a stack according to a predefined geometric pattern,
wherein the uncured three-dimensional structure is configured to be cured after formation of the entire three-dimensional structure.
20. The product as recited in claim 19 , wherein the product is a silicone-based three-dimensional structure, wherein the filaments of the three-dimensional structure have a diameter greater than about 100 microns.
21. The product as recited in claim 19 , comprising a first layer and a second layer, wherein continuous filaments of the second layer are different than continuous filaments of the first layer, wherein the second layer is in a z-direction perpendicular to an x-y plane of the first layer.
22. The product as recited in claim 19 , wherein a portion of at least one of each of the plurality of layers comprises a continuous filament comprising a second material, wherein a hardness of the second material and a hardness of the first material are different.