DUAL CURE EPOXY 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 epoxy composition comprising at least one epoxy resin, at least one monomer and/or prepolymer that is polymerizable by exposure to radiation and at least one photoinitiator, wherein the pasty epoxy 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 by heating to obtain the three-dimensional part; wherein the printable composition is a pasty epoxy composition comprising at least one epoxy resin; at least one monomer and/or prepolymer that is polymerizable by exposure to radiation; and at least one photoinitiator; wherein the pasty epoxy 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 epoxy 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 epoxy resin is selected from aliphatic epoxy resins.

7. The method of claim 1, wherein the at least one monomer and/or prepolymer that is polymerizable by exposure to radiation is selected from di-, triacrylates and/or mixtures thereof.

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

9. The method of claim 1, wherein the printable composition contains additionally a dual reactive compound.

10. The method of claim 1, wherein the printable composition comprises further at least one compound having at least one oxetane group.

11. The method of claim 1, wherein the pasty epoxy composition contains at least one organic hardener co- polymerizable with said epoxy resin.

12. The method of claim 1, wherein the pasty epoxy composition further comprises core-shell particles.

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

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

Description

EXAMPLES

[0086] The printable composition has been prepared by the components as mentioned in following table.

[0087] The printable composition had a pasty behaviour with a viscosity factor (1.5/15) in the desired range (see table; measured as mentioned in the description).

[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 at 100° C. for 27 minutes.

[0089] Objects printed with the inventive compositions 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. Objects printed with the composition according to the comparative examples 1 and 2 show a lower resolution and rough surfaces, in case 3D printing was possible at all.

TABLE-US-00001 E1 E2 E3 E4 E5 E6 E7 E8 E9 Aliph. Epoxy Resin 1 13.67 16.57 16.16 16.16 13.67 Aliph. Epoxy Resin 2 23.67 13.50 Arom. Epoxy Resin  24.62 Oxetane 10.00 11.82 11.82 10.00 10.00 CSR 1 39.59 14.11 14.11 14.11 16.68 16.68 14.11 14.11 CSR 2 8.32 CSR 3  33.53 Polyol 1 8.32 8.32 9.83 9.83 8.32 8.32 Polyol 2  10.42 Adhesion promoter 1.57 8.32 1.57 1.86 1.86 1.57 1.57  2.56 GLYMO 0.24 0.24 0.24 0.28 0.28 0.24 0.24 Epoxy Acrylate 1 10.00 11.82 11.82 10.00 10.00 Epoxy Acrylate 2 10.00 10.00 10.00 Triacrylate 3.00 3.00 3.00 3.00 3.55 3.55 3.00 3.00  3.00 Diacrylate 6.20 6.20 6.20 6.20 7.33 7.33 6.20 6.20  6.00 Surfactant 2.65 2.65 2.65 2.65 3.13 3.13 2.65 2.65 Amorphous fumed silica 7.88 Pigment 0.15  0.03 Fumed silica 5.49 1.49 5.49 5.49 7.88 9.49 9.49 Calcium Oxide  2.80 Boron Nitride 1.18 1.18 1.18 1.18 1.18 1.18 Calcium metasicate  8.90 wollastonite Bariumsulftat 19.59 23.59 19.59 19.59 4.93 4.93 15.59 15.59 Cationic curing catalyst 1.00 1.00 1.00 1.00 1.18 1.18 1.00 1.00 Fenuron  0.50 Dicyandiamide  4.64 Hydrophob fumed silica  2.00 Photoinitiator 1 3.00 3.00 3.00 3.00 3.55 3.55 3.00 3.00 Photoinitiator 2  1.00 Sum η (1.5/s) at 25° C. [Pas] 116 3.8 38 42 563 1218 116 178 163* η (15/s) at 25° C. [Pas] 70 8 8 9 74 116 25 41  32* Viscosity factor (1.5/15) 1.66 0.48 4.7 4.7 7.6 10.5 4.6 4.3  5* *at 55° C.

TABLE-US-00002 Aliph. (3′,4′-Epoxycyclohexane)methyl-3,4- Epoxy epoxycyclohexylcarboxylate, liquid, Epoxy Resin 1 Equivalent 130 g/eq Aliph. (3′,4′-Epoxycyclohexane)methyl-3,4- Epoxy epoxycyclohexylcarboxylate modified epsilon- Resin 2 caprolactone, liquid Arom. Epoxy resin based on bisphenol A and epichorohydrin, Epoxy liquid, Epoxy Equivalent 187 g/eq Resin Oxetane Bis(3-ethyl-3-oxethanyl)methoxymethyl)biphenyl CSR 1 30% CSR (vinyl acrylic copolymer) in liquid cycloaliphatic epoxy resin CSR 2 methacrylate-butadiene-styrene core-shell CSR 3 40% CSR in unmodified liquid epoxy resin based on bisphenol A Polyol 1 Polyethylene glycol, molecular weight 400 g/mol Polyol 2 Polyol, OH value 1 - 1.15 eq/kg GLYMO 3-Glycidyloxypropyltrimethoxysilan Epoxy Liquid epoxy methacrylate resin based on bisphenol Acrylate 1 A diglycidylether Epoxy Liquid EPOXY ACRYLATE OLIGOMER Acrylate 2 Triacrylate TRIMETHYLOLPROPANE TRIACRYLATE (TMPTA) Diacrylate ETHOXYLATED BISPHENOL A DIACRYLATE Cationic Catalyst based on hexafluoroantimonate curing catalyst Photo- Mixture of Oxyphenyl-acetic acid 2-(2-oxo-2-phenyl- initiator 1 acetoxy-ethoxy)- and Oxyphenyl-acetic acid 2- [2-hydroxy-ethoxy]-ethyl ester Photo- Bis(2,4,6-Trimethylbenzoyl)phenylphosphine oxide initiator 2