Thixotropic, thermosetting resins for use in a material extrusion process in additive manufacturing
View Patent ↗Methods of preparing a three-dimensional structure are provided. One method includes the steps of extruding beads of thixotropic thermoset materials, and subjecting the beads to curing conditions such that the thixotropic thermoset materials at least partially cure to form cured polymer layers. In some cases, the curing conditions are not applied until multiple beads are extruded and in contact with one another. The steps of these methods can be performed repeatedly as desired to prepare a three-dimensional structure of nearly limitless shapes by additive manufacturing processes. Thixotropic thermoset materials are also provided, as are three-dimensional objects formed therefrom.
1. A method of preparing a three-dimensional structure, the method comprising:
i. extruding a first bead of a first thixotropic thermoset material onto a support, wherein the first thixotropic thermoset material comprises a first thermoset resin and a first rheology control agent;
ii. subjecting the first bead to curing conditions such that the thixotropic thermoset material is at least partially cured to form a cured first polymer layer;
iii. extruding a second bead of a second thixotropic thermoset material in contact with the cured first polymer layer, wherein the second thixotropic thermoset material comprises a second thermoset resin and a second rheology control agent; and
iv. subjecting the second bead of thixotropic thermoset material to curing conditions, wherein the second bead of thixotropic thermoset material is at least partially cured to form a cured second polymer layer, and wherein the three-dimensional structure is prepared,
wherein the first and/or second thixotropic thermoset material has a thixotropic index that is greater than 5, and the first and/or second thixotropic thermoset material does not contain a catalyst.
2. The method of claim 1 , wherein the first and/or second thermoset resin is selected from the group consisting of phenolic resins; lignin resins; tannin resins; amino resins; polyimide resins; isocyanate resins; (meth)acrylate resins; vinylic resins; styrenic resins; polyester resins; melamine resins; vinyl ester resins; maleimide resins; epoxy resins; polyamidoamine resins; and mixtures thereof.
3. A method of preparing a three-dimensional structure, the method comprising:
i. extruding a first bead of a first thixotropic thermoset material onto a support, wherein the first thixotropic thermoset material comprises a first thermoset resin and a first rheology control agent;
ii. subjecting the first bead to curing conditions such that the thixotropic thermoset material is at least partially cured to form a cured first polymer layer;
iii. extruding a second bead of a second thixotropic thermoset material in contact with the cured first polymer layer, wherein the second thixotropic thermoset material comprises a second thermoset resin and a second rheology control agent; and
iv. subjecting the second bead of thixotropic thermoset material to curing conditions, wherein the second bead of thixotropic thermoset material is at least partially cured to form a cured second polymer layer, and wherein the three-dimensional structure is prepared,
wherein the first and/or second thixotropic thermoset material has a thixotropic index that is greater than 5, and the first and/or second thixotropic thermoset material does not contain a catalyst,
wherein the first and/or second thermoset resin is selected from the group consisting of polyamidoamine-epichlorohydrin adduct resins, phenolic resins, amino resins, epoxy resins, isocyanate resins, isocyanate-terminated urethane resins and acrylate/methacrylate resins.
4. The method of claim 1 , wherein the first cured polymer layer is cross-linked with the second cured polymer layer.
5. The method of claim 1 , wherein the first and/or second thixotropic thermoset material is capable of flowing when subjected to an external shear stress and at zero shear rate having a yield strength or yield point such that the first and/or second thixotropic thermoset material does not flow.
6. The method of claim 1 , wherein the steps of subjecting the first or second beads to curing conditions comprise irradiating the first or second bead with thermal energy.
7. The method of claim 1 , wherein the steps of subjecting the first or second bead to curing conditions comprise subjecting the first or second bead to visible or invisible light, UV-radiation, IR-radiation, electron beam radiation, X-ray radiation or laser radiation.
8. The method of claim 1 , wherein the first and/or second rheology control agent comprises fumed silica, organoclays, polysaccharides, cellulose and derivatives thereof.
9. The method of claim 1 , wherein the steps of extruding a first or second bead of the first or second thixotropic thermoset material comprise subjecting the first or second thixotropic thermoset material to an external shear stress to cause the first or second thixotropic thermoset material to be extruded through an extrusion nozzle.
10. The method of claim 1 , wherein the first thixotropic thermoset material has the same composition as the second thixotropic thermoset material.
11. The method of claim 1 , wherein the first and/or second thixotropic thermoset material is extruded through a heated nozzle that initiates curing of the first and/or second thixotropic thermoset material.
12. A method of preparing a three-dimensional structure, the method comprising:
i. extruding a first bead of a first thixotropic thermoset material onto a support, wherein the first thixotropic thermoset material comprises a first thermoset resin and a first rheology control agent, and wherein the first thixotropic thermoset material has a thixotropic index that is greater than 5;
ii. extruding a second bead of a second thixotropic thermoset material, wherein the second bead is in contact with the first bead, wherein the second thixotropic thermoset material comprises a second thermoset resin and a second rheology control agent, and wherein the second thixotropic thermoset material has a thixotropic index that is greater than 5; and
iii. subjecting the first and second beads to curing conditions to form cured first and second polymer layers, respectively,
wherein the cured first polymer layer is cross-linked with the cured second polymer layer,
wherein the first and/or second thixotropic thermoset material does not contain a catalyst and wherein the three-dimensional structure is prepared.
13. The method of claim 12 , further comprising successively repeating steps i. and ii, prior to step iii to form the three-dimensional structure comprising a plurality of cured polymer layers, wherein adjacent cured polymer layers are cross-linked with each other.
14. The method of claim 12 , wherein the step of subjecting the first and second beads to curing conditions comprises heating the first and second beads to a temperature ranging from about 25 to about 125° C.
15. The method of claim 12 , wherein first thixotropic thermoset material has the same composition as the second thixotropic thermoset material.
16. The method of claim 12 , wherein the first and/or second thermoset resin is selected from the group consisting of phenolic resins; lignin resins; tannin resins; amino resins; polyimide resins; isocyanate resins; (meth)acrylate resins; vinylic resins; styrenic resins; polyester resins; melamine resins; vinyl ester resins; maleimide resins; epoxy resins; polyamidoamine resins; and mixtures thereof; and wherein the first and/or second rheology control agent comprises fumed silica, organoclays, polysaccharides, cellulose and derivatives thereof.