3D reverse printing method and device

1. A material system for 3D printing wherein the material system comprises:

a particulate build material for applying to a build space in a defined layer thickness in the form of a powder or a dispersion, and

a liquid for selectively applying via a print head to the particulate build material in one or more areas in which the particulate build material is not to be solidified by a solidification reaction;

wherein the particulate build material is selected so that a solidification reaction of the particulate build material has already started, starts or may be started by introducing energy upon the application of the particulate build material, and

the liquid is selected for inhibiting or stopping the solidification reaction;

wherein the particulate build material is selected from the group consisting of a freshly mixed concrete or mortar, a mixture of a filler and a reactive resin system, a mixture of a foundry molding material and a reactive resin system common in foundries, a mixture of a filler and water glass, and a mixture of particles and a meltable material;

with the proviso that the mixture of particles and the meltable material is heated to a temperature above the melting temperature of the meltable material prior to application.

2. The material system of claim 1 , wherein the particulate build material is a mixture of a foundry molding material and a reactive resin system common in foundries, or a mixture of a filler and water glass.

3. The material system of claim 2 , wherein the liquid is a reaction-inhibiting liquid.

4. The material system of claim 3 , wherein the liquid is a reaction-stopping liquid.

5. A material system for 3D printing wherein the material system comprises:

a particulate build material for applying to a build space in a defined layer thickness in the form of a powder or a dispersion, wherein the particulate build material solidifies by a salification reaction including a hydration, and

a liquid for selectively applying via a print head to the particulate build material in one or more areas in which the particulate build material is not to be solidified by a solidification reaction;

wherein the particulate build material is selected so that a solidification reaction of the particulate build material has already started, starts or may be started by introducing energy upon the application of the particulate build material, and

the liquid is selected for inhibiting or stopping the hydration.

6. The material system of claim 1 , wherein the particulate build material solidifies by a solidification reaction including a polymerization.

7. The material system of claim 1 , wherein the particulate build material solidifies by a phase transition.

8. The material system of claim 1 , wherein the particulate build material includes a powder material and a binding agent, wherein the powder material includes a sand, a ceramic powder, a metal powder, a wood particle, a fibrous material, a cellulose, or a lactose powder.

9. The material system of claim 8 , wherein the binding agent includes an acrylate, a styrene, a polyurethane, an epoxy resin, a polyester or a polyamide.

10. The material system of claim 9 , wherein particulate build material includes products of a solidification reaction of the particulate build material.

11. A material system of claim 1 , for 3D printing wherein the material system comprises:

a particulate build material for applying to a build space in a defined layer thickness in the form of a powder or a dispersion, and

a liquid for selectively applying via a print head to the particulate build material in one or more areas in which the particulate build material is not to be solidified by a solidification reaction;

wherein the particulate build material is selected so that a solidification reaction of the particulate build material has already started, starts or may be started by introducing energy upon the application of the particulate build material, and

the liquid is selected for inhibiting or stopping the solidification reaction;

wherein the liquid includes a monofunctional reactant.

12. A material system for 3D printing wherein the material system comprises:

a particulate build material for applying to a build space in a defined layer thickness in the form of a powder or a dispersion, and

a liquid for selectively applying via a print head to the particulate build material in one or more areas in which the particulate build material is not to be solidified by a solidification reaction;

wherein the particulate build material is selected so that a solidification reaction of the particulate build material has already started, starts or may be started by introducing energy upon the application of the particulate build material, and

the liquid is selected for inhibiting or stopping the solidification reaction;

wherein the particulate build material is a self-hardening material mixture.

13. The material system of claim 12 , wherein the liquid slows down or prevents a self-hardening reaction of the particulate build material.

14. A material system for 3D printing wherein the material system comprises:

a particulate build material for applying to a build space in a defined layer thickness in the form of a powder or a dispersion, and

a liquid for selectively applying via a print head to the particulate build material in one or more areas in which the particulate build material is not to be solidified by a solidification reaction;

wherein the particulate build material is selected so that a solidification reaction of the particulate build material has already started, starts or may be started by introducing energy upon the application of the particulate build material, and

the liquid is selected for inhibiting or stopping the solidification reaction;

wherein the liquid includes an acidic sugar solution, an acid, or a hydrophobic solution.

15. A material system for 3D printing wherein the material system comprises:

i) a build material for applying to a build space in a defined layer thickness in the form of a paste-like substance, wherein the build material includes an aggregate material, a paste, water, and optionally additives; and

ii) a liquid for selectively applying via a print head to the build material in one or more areas in which the particulate build material is not to be solidified, wherein the liquid interferes with a hydration of the build material or interferes with a solidification reaction of the build material.

16. The material system of claim 15 , wherein the aggregate includes a metal or a ceramic, optionally wherein a solidification reaction of the build material has started prior to applying to a build space and/or prior to introduction of energy.

17. The material system of claim 15 , wherein the paste is a cement paste and the liquid includes an acidic sugar solution that interferes with hydration of the cement;

optionally wherein a solidification reaction of the build material has started prior to applying to the build space and/or prior to introduction of energy.

18. A material system for 3D printing wherein the material system comprises:

i) a build material for applying to a build space in a defined layer thickness including a powder material and a phase change material, wherein the build material is above a melting temperature of the phase change material; and

ii) a liquid for selectively applying via a print head to the build material in one or more areas in which the particulate build material is not to be solidified, wherein the liquid interferes with the solidification of the phase change material.

19. The material system of claim 18 , wherein the build material is in a coater device and the build material has a temperature above the melting temperature of the phase change material prior to application by the coater device to the build space.