Coextrusion ink chemistry for improved feature definition
View Patent ↗Improved coextruded ribbons of material, such as can be used for making relatively fine conductive or ceramic lines or structures, having relatively high aspect ratios, are provided. The inks used to form the coextruded structures lack a yield stress and a high viscosity, but react at their interface to form a material having a finite yield stress or a high viscosity. This material then supports the shape of the extruded ink such that structures can be formed therefrom.
1. A coextruded ink derived from a coextrusion ink set comprised of:
a first ink having a yield stress less than 100 Pa and a zero-shear viscosity less than 50 Pa*s;
one of a second ink or a sacrificial material, the second ink or sacrificial material having a yield stress less than 100 Pa and a zero-shear viscosity less than 50 Pa*s;
wherein the coextruded ink includes an interface layer having a yield stress greater than 100 Pa or a zero-shear viscosity greater than 50 Pa*s and wherein, the interface layer is formed between the first ink and the one of the second ink or sacrificial material as a result of localized mixing of the first ink and the one of the second ink or sacrificial material.
2. The coextruded ink of claim 1 , wherein the interface layer of coextruded ink prevents mixing of the first ink and the one of the second ink or sacrificial material beyond the localized mixing that forms the coextruded ink.
3. The coextruded ink of claim 1 , wherein the first ink further comprises solid particles.
4. The coextruded ink of claim 3 , wherein the solid particles comprise at least one material selected from the group consisting of a metal, a ceramic, a polymer and a semiconductor.
5. The coextruded ink of claim 3 , wherein the solid particles comprise a volume fraction in excess of 20% of the first ink.
6. The coextruded ink of claim 3 , wherein the solid particles have a net electrostatic charge.
7. The coextruded ink of claim 3 , wherein the solid particles are dispersed in a solvent of the first ink.
8. The coextruded ink of claim 1 , wherein the interface layer of the coextruded ink formed by gelation.
9. The coextruded ink of claim 8 , wherein the gelation occurs via the neutralization of electrostatic charge on the solid particles.
10. The coextruded ink of claim 1 , wherein the interface layer of the coextruded ink is formed by chemical bonding of materials in the first ink and the one of the second ink or sacrificial material.
11. The coextruded ink of claim 1 , wherein the interface layer of the coextruded ink has a yield stress greater than 1,000 Pa.
12. The coextruded ink of claim 1 , wherein the interface layer of the coextruded ink has a thickness of greater than 1 micron.