DUAL CURE POLYURETHANE FORMULATIONS FOR 3D PRINTING APPLICATIONS

Abstract

The present invention lies in the field of 3D printing methods. In particular, the invention relates to 3D printing methods for the production of a 3D part in a layer-by-layer manner, wherein the printable composition is a pasty polyurethane composition comprising at least one polyisocyanate resin, at least one monomer and/or prepolymer that is polymerizable by exposure to radiation and at least one photoinitiator, wherein the pasty polyurethane composition has a viscosity factor (1.5/15) of at least 2 at application temperature.

Claims

1. Method for additive manufacturing a three-dimensional part in a layer-by-layer manner, wherein the method comprises (i) providing a carrier substrate to support the three-dimensional part and a print head connected to a reservoir of a printable composition; (ii) printing the printable composition with the print head in form of extrudate strands onto the carrier substrate to form a first layer; (iii) printing the printable composition with the print head in form of extrudate strand onto the first layer to form a second layer; (iv) optionally repeating step (iii) at least once to form a third or subsequent layer; (v) exposing the printable composition directly after printing and/or after each layer application and/or after application of multiple layer to radiation; and (vi) curing the printed layers of the reactive curable printable composition to obtain the three-dimensional part; wherein the printable composition is a pasty polyurethane composition comprising at least one polyisocyanate resin; at least one monomer and/or prepolymer that is polymerizable by exposure to radiation; and at least one photoinitiator; wherein the pasty polyurethane composition has a viscosity factor (1.5/15) of at least 2 at application temperature.

2. The method of claim 1, wherein the distance of the print head orifice to the carrier substrate or the already formed layers is equal to or greater than the thickness of the printed extrudate strand.

3. The method of claim 1, wherein viscosity factor (1.5/15) at application temperature of at least 3.0.

4. The method of claim 1, wherein the application temperature is in the range from 15° C. to 80° C.

5. The method of claim 1, wherein the pasty polyurethane composition has a viscosity at a shear rate of 1.5/s of at least 10 Pas.

6. The method of claim 1, wherein the at least one polyisocyanate is an aliphatic polyisocyanate.

7. The method of claim 1, wherein the at least one monomer and/or prepolymer that is polymerizable by exposure to radiation is a dual reactive compound.

8. The method of claim 1, wherein the printable polyurethane composition further comprises an isocyanate curing catalyst.

9. The method of claim 1, wherein pasty polyurethane composition contains at least one polyol.

10. Three-dimensional article manufactured by use of the method of claim 1.

11. A printable composition for additive manufacturing to form a three-dimensional part in a layer-by-layer manner, wherein the printable composition is a pasty polyurethane composition comprising at least one polyisocyanate resin; at least one monomer and/or prepolymer that is polymerizable by exposure to radiation; and at least one photoinitiator; wherein the polyurethane composition has a viscosity factor (1.5/15) of at least 2 at application temperature.

Description

EXAMPLES

[0087] The printable composition has been prepared by mixing at 80° C. 20 parts of triisocyanurate of hexamethylene diisocyanate, 13 parts of 2-hydroxyethylmethacrylate, 6.5 parts of a saturated copolyester containing hydroxyl groups, 0.07 parts dibutyltindilaurat, 60 parts of aluminium hydroxide and 1 part of a photoinitiator based on oxyphenyl acetic acid esters.

[0088] The printable composition were printed using a standard procedure for application of dual cure formulations using a Loctite 300 application robot and a Loctite UV cure cabinet (UVA Loc 1000) plus standard oven. After printing of each layer the layer has been pre-cured using a UV chamber (UVALOC 1000; 3rd platform, 5 s, 1000 W) or a UV LED. In this manner the layers have been printed on top of each other the gain a three-dimensional structure. After UV-curing the final layer, the printed object was put into an oven to final cure the printed structure.

[0089] The printable composition had a pasty behaviour with a viscosity factor (1.5/15) in the desired range. Objects printed with this composition by using the inventive method show a high resolution with a smooth surface and at the same time have a good interlayer adhesion and strong mechanical properties.