Powder-based additive manufacturing process at low temperatures

Patent metadata

Field	Value
Publication number	US-10926459-B2
Application number	US-201716331221-A
Country	US
Kind code	B2
Filing date	Sep 11, 2017
Priority date	Sep 12, 2016
Publication date	Feb 23, 2021
Grant date	Feb 23, 2021

Abstract

A process for manufacturing an article comprises the steps of: applying a layer that consists of particles to a target area; allowing, in a chamber, energy to act on a selected portion of the layer, according to a cross-section of the article, so that the particles in the selected portion are bonded, and repeating the steps of applying and allowing energy to act for a plurality of layers so that the bonded portions of the adjacent layers are bonded to form the article, at least part of the particles comprising a fusible polymer. The fusible polymer has a fusion range (DSC, differential scanning calorimetry; 2nd heating at a heating rate of 5 K/min.) of ≥20° C. to ≤100° C. The fusible polymer further has a complex viscosity \η*\ (determined by viscosity measurement in the melt using a plate-plate oscillating viscometer according to ISO 6721-10 at 100° C. and a shear rate of 1/s) of ≥10 Pas to ≤1000000 Pas. Finally, the temperature inside the chamber is ≤50° C. The invention also relates to an article manufactured by the process according to the invention, to an article having a substrate and to an article bonded to the substrate, the article being in the form of an adhesive joint or varnish region, and to the use of a particular polyurethane in powder-based additive manufacturing processes.

First claim

The invention claimed is:

1. A method of producing an article, comprising the steps of:
applying a layer of particles to a target surface;
introducing energy into a selected portion of the layer corresponding to a cross section of the article in a chamber such that the particles in the selected portion are bonded;
repeating the steps of applying and introducing energy for a multitude of layers, such that the bonded portions of the adjacent layers become bonded in order to form the article;

where at least some of the particles include a fusible polymer;
wherein
the fusible polymer has a melting range (DSC, differential scanning calorimetry, 2nd heating operation at heating rate 5 K/min.) of ≥20° C. to ≤100° C.,
the fusible polymer has a magnitude of the complex viscosity |η*| (determined by viscometry measurement in the melt with a plate/plate oscillation viscometer according to ISO 6721-10 at 100° C. and a shear rate of 1/s) of ≥10 Pas to ≤1 000 000 Pas
and in that the temperature within the chamber is ≤50° C.

2. The method as claimed in claim 1 , wherein the introducing of energy into a selected portion of the layer corresponding to a cross section of the article such that the particles in the selected portion are bonded comprises the following step:
irradiating a selected portion of the layer corresponding to a cross section of the article with a beam of energy in the chamber such that the particles in the selected portion are bonded.

3. The method as claimed in claim 1 , wherein the introducing of energy into a selected portion of the layer corresponding to a cross section of the article such that the particles in the selected portion are bonded comprises the following steps:
applying a liquid to a selected portion of the layer corresponding to a cross section of the article, where said liquid increases the absorption of energy in the regions of the layer with which it comes into contact relative to the regions with which it does not come into contact;
irradiating the layer in the chamber such that the particles in regions of the layer that come into contact with the liquid are bonded to one another and the particles in regions of the layer that do not come into contact with the liquid are not bonded to one another.

4. The method as claimed in claim 1 , wherein the interior of the chamber is cooled at least at times or wherein the interior of the chamber is not heated at least at times.

5. The method as claimed in claim 1 , wherein the fusible polymer has a Shore hardness (DIN ISO 7619-1) of ≥40 Shore A to ≤80 Shore D.

6. The method as claimed in claim 1 , wherein the fusible polymer is selected from the group consisting of polyurethane, polyester, polyalkylene oxide, plasticized PVC, polyamide, protein or combination of at least two of these.

7. The method as claimed in claim 6 , wherein the fusible polymer is a polyurethane obtainable from the reaction of a polyisocyanate component and a polyol component, said polyol component comprising a polyesterpolyol having a no-flow point (ASTM D5985) of ≥25° C.

8. The method as claimed in claim 1 , wherein the fusible polymer, after heating to 100° C. and cooling to 20° C. at a cooling rate of 4° C./min, within a temperature interval from 25° C. to 40° C. for ≥1 minute, has a storage modulus G′ (determined at the respective temperature with a plate/plate oscillation viscometer according to ISO 6721-10 at a shear rate of 1/s) of ≥100 kPa to ≤1 MPa and, after cooling to 20° C. and storage at 20° C. for 120 minutes, has a storage modulus G′ (determined at 20° C. with a plate/plate oscillation viscometer according to ISO 6721-10 at a shear rate of 1/s) of ≥10 MPa.

9. The method as claimed in claim 1 , wherein at least some of the particles include the fusible polymer and a further polymer and/or inorganic particles.

10. The method as claimed in claim 1 , wherein the article formed is subjected to an aftertreatment selected from the group consisting of: mechanical smoothing of the surface, controlled local heating, heating of the entire article, controlled local cooling, cooling of the entire article, contacting of the article with steam, contacting of the article with the vapor of an organic solvent, irradiating the article with electromagnetic radiation, immersing the article into a liquid bath, or a combination of at least two of these.

11. The method as claimed in claim 1 , wherein the particles, after the step of applying a layer of particles to the target surface, are at least partly suspended in a liquid phase.

12. The method as claimed in claim 1 , wherein the article is formed on a substrate and, on conclusion of the method, remains bonded to the substrate.

13. An article produced by a method as claimed in claim 1 .

14. The article as claimed in claim 13 , wherein the article takes the form of a shaped adhesive body.

15. An article produced by a method as claimed in claim 12 , having a substrate and an article bonded to the substrate, wherein the article takes the form of an adhesive join or of a varnish region.

Assignees

• Covestro Deutschland Ag

Inventors

• Achten Dirk
• Büsgen Thomas
• Dijkstra Dirk
• Degiorgio Nicolas
• Arndt Wolfgang
• Akbas Levent
• Wagner Roland
• Reichert Peter
• Büchner Jörg

Classifications

• B33Y70/00

  Materials specially adapted for additive manufacturing · CPC title

• B33Y10/00

  Processes of additive manufacturing · CPC title

• B29C64/153 Primary

  using layers of powder being selectively joined, e.g. by selective laser sintering or melting · CPC title

• B33Y80/00

  Products made by additive manufacturing · CPC title

• B29K2995/0012

  having particular thermal properties · CPC title