Method of treating at least part of the surface of a 3D-printed article

Patent metadata

Field	Value
Publication number	US-10300660-B2
Application number	US-201715791735-A
Country	US
Kind code	B2
Filing date	Oct 24, 2017
Priority date	Oct 25, 2016
Publication date	May 28, 2019
Grant date	May 28, 2019

Abstract

A method of treating at least part of a surface ( 110 ) of an article ( 100 ) in which an article ( 100 ) is treated, at least part of a surface ( 110, 111 ) of the article having been produced by an additive manufacturing method from a construction material, and the construction material provides a temperature T G′ at which the storage modulus G′ of the construction material (determined by dynamic-mechanical analysis according to ISO 6721 at a shear rate of 1/s) is 10 MPa. The article is preferably placed into an evacuable volume and the volume is evacuated. By heating and exerting pressure, the surface is plastically deformed and can be smoothed thereby.

First claim

The invention claimed is:

1. A method of treating at least a part of a surface of an article comprising the steps of:
I) providing the article at least a part of the surface of the article having been produced by an additive manufacturing method from a construction material, and the construction material provides a temperature T G′ at which the storage modulus G′ of the construction material (determined by dynamic-mechanical analysis according to ISO 6721 at a shear rate of 1/s) is 10 MPa, wherein the treating of at least a part of the surface comprises the action of pressure on the surface at a temperature of the surface above the temperature T G ;′
II) placing the article into an evacuable volume having a boundary comprising flexible sections intended for contact with the surface of the article, wherein the material for the boundary is selected such that it does not enter into any permanent bond with the construction material that has been heated above its
temperature T G′ and then cooled below its temperature T G′ ;

III) evacuating the volume, such that at least some of the flexible sections of the boundary of the volume come into contact with the surface of the article;
IV) heating at least a portion of the surface of the article, while the volume still remains evacuated, for a predetermined period of time to a temperature above the temperature T G′ ;
V) cooling the surface of the article to a temperature below the temperature T G′ ;
VI) removing the article from the volume.

2. The method according to claim 1 , wherein the boundary of the evacuable volume does not have any inflexible sections.

3. The method according to claim 1 , wherein the material of the flexible sections of the boundary of the evacuable volume is selected from the group consisting of polyethylene, polypropylene, polyvinyl chloride, polytetrafluoroethylene and a combination of at least two of these.

4. The method according to claim 1 , wherein the material of the flexible sections of the boundary of the evacuable volume is selected from the group consisting of crosslinked polyethylene, crosslinked polypropylene, crosslinked polyvinyl chloride, crosslinked polytetrafluoroethylene, silicone rubber, fluorosilicone rubber, fluoro rubber and a combination of at least two of these.

5. The method according to claim 1 , wherein, in step II), the flexible sections of the boundary exert an average pressure of ≥10 kPa to ≤1000 kPa on the surface of the article.

6. The method according to claim 1 , wherein production of the article by means of the additive manufacturing method comprises the steps of:
applying a layer of particles including the construction material to a target surface;
introducing 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;
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.

7. The method according to claim 6 , 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, such that the particles in the selected portion are bonded.

8. The method according to claim 6 , 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 the energy introduced 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 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.

9. The method according to claim 1 , wherein production of the article by means of the additive manufacturing method comprises the steps of:
applying a filament of an at least partly molten construction material to a carrier, such that a layer of the construction material is obtained, corresponding to a first selected cross section of the article;
optionally applying a filament of the at least partly molten construction material to a previously applied layer of the construction material, such that a further layer of the construction material is obtained, which corresponds to a further selected cross section of the article and which is bonded to the layer applied beforehand;
optionally repeating the step of applying a filament of the at least partly molten construction material to a previously applied layer of the construction material until the article has been formed.

10. The method according to claim 1 , wherein the construction material comprises a thermoplastic polyurethane elastomer having a melting range (DSC, differential scanning calorimetry; second heating at a heating rate 5 K/min) of ≥20° C. to ≤200° C., a Shore hardness according to DIN ISO 7619-1 of ≥40 A to
≤85 D and a melt volume rate (MVR) according to ISO 1133 (190° C., 10 kg) of ≥25 to
≤190 cm 3 /10 min, preferably of ≥25 to ≤90 cm 3 /10 min.

11. The method according to claim 1 , wherein the construction material comprises a thermoplastic polyurethane elastomer having
a melting range (DSC, differential scanning calorimetry; second heating at a heating rate 5 K/min) of ≥20° C. to ≤240° C., preferably of ≥20° C. to ≤200° C.,
a Shore A hardness according to DIN ISO 7619-1 of ≥40 A to ≤85 D,
a melt volume rate (MVR) according to ISO 1133 (10 kg) at a temperature, T, of 5 to 15 cm 3 /10 min and
a change in the melt volume rate (10 kg) in the event of an increase in this temperature, T, by 20° C. of ≤90 cm 3 /10 min.

12. The method according to claim 1 , wherein the construction material comprises a thermoplastic polyurethane elastomer obtained from reaction of the following components:
a) at least one organic diisocyanate
b) at least one compound having groups reactive toward isocyanate groups and having a number-average molecular weight (M n ) of ≥500 g/mol to <6000 g/mol and a number-average functionality of the totality of the components covered by b) of ≥1.8 to ≤2.5
c) at least one chain extender having a molecular weight (Mn) of 60-450 g/mol and a number-average functionality of the totality of the chain extenders covered by c) of 1.8 to 2.5.

13. The method according to claim 1 , wherein the construction material comprises a thermoplastic polyurethane elastomer having a melting range (DSC, differential scanning calorimetry; 2nd heating at a heating rate 5 K/min.) of
≥20° C. to ≤100° C. and a magnitude of the complex viscosity |η*| (determined by
viscometry measurement in the melt with a plate/plate oscillation shear viscometer at 100° C. and a shear rate of 1/s) of ≥10 Pas to ≤1 000 000 Pas.

14. The method according to claim 1 , wherein the construction material comprises a thermoplastic polyurethane elastomer obtained from the reaction of a polyisocyanate component and a polyol component, said polyol component comprising a polyester polyol having a pour point (ASTM D5985) of ≥25° C.

Assignees

• Covestro Deutschland Ag

Inventors

• Achten Dirk
• Büsgen Thomas
• Wagner Roland
• Mettmann Bettina
• Akbas Levent
• Guiu Julien

Classifications

• B29C2071/022

  Annealing · CPC title

• B33Y80/00

  Products made by additive manufacturing · CPC title

• B29K2995/007

  Hardness · CPC title

• B29C64/165

  using a combination of solid and fluid materials, e.g. a powder selectively bound by a liquid binder, catalyst, inhibitor or energy absorber · CPC title

• B29K2995/0046

  Elastic · CPC title