Liquid, hybrid UV/VIS radiation curable resin compositions for additive fabrication
Liquid radiation curable compositions are disclosed which are suitable for hybrid (i.e. cationic and free-radical) polymerization when processed via additive fabrication equipment utilizing sources of actinic radiation with peak spectral intensities in the UV/vis region. Also disclosed are methods of creating three-dimensional parts via additive fabrication processes utilizing sources of actinic radiation with peak spectral intensities in the UV/vis region employing liquid radiation curable compositions suitable for hybrid polymerization, and the parts cured therefrom.
1. A liquid radiation curable composition for additive fabrication comprising, relative to the weight of the entire composition:
(a) from 10 to 80 wt. % of a cationically polymerizable component comprising a cycloaliphatic epoxide and an oxetane;
(b) from 0.1 to 10 wt. % of an iodonium salt cationic photoinitiator;
(c) from 0.1 to 10 wt. % of a photosensitizer for photosensitizing component (b);
(d) from 1 to 8 wt. % of a first reductant for reducing component (b);
(e) up to 50 wt. % of a free-radically polymerizable component;
(f) optionally, a free-radical photoinitiator; and
(g) from 1 to 25 wt. % of a second reductant for reducing component (b) possessing an electron-donating substituent attached to a vinyl group;
wherein the composition possesses a cycloaliphatic epoxide T 95 value, a cycloaliphatic epoxide plateau conversion, an oxetane T 95 value, and an oxetane plateau conversion;
wherein the cycloaliphatic epoxide T 95 value of the composition is less than about 70 seconds, the cycloaliphatic plateau conversion of the composition is greater than about 20%; the oxetane T 95 value of the composition is less than about 48 seconds, and the oxetane plateau conversion of the composition is greater than about 29%;
wherein the cycloaliphatic epoxide T 95 value, the cycloaliphatic epoxide plateau conversion, the oxetane T 95 value, and the oxetane plateau conversion of the composition are each measured by Real Time Fourier Transform Infrared (FTIR) spectroscopy upon subjecting the composition to UV/vis optics emitting radiation with a peak spectral output at 400 nm and an irradiance at a surface of the composition of 2 mW/cm 2 for 10 seconds.
2. The liquid radiation curable composition for additive fabrication of claim 1 , wherein the (d) first reductant is a free-radical photoinitiator which reduces component (b) upon forming a free-radical after dissociation upon being subjected to actinic radiation at UV/vis wavelengths.
3. The liquid radiation curable composition for additive fabrication of claim 2 , wherein
a weight ratio of (b) the iodonium salt cationic photoinitiator to (c) the photosensitizer for photosensitizing component (b) to (d) the first reductant for reducing component (b) to (g) the second reductant for reducing component (b) possessing an electron-donating substituent attached to a vinyl group is from about 2:2:1:2 to about 20:1:5:25.
4. The liquid radiation curable composition for additive fabrication of claim 3 , wherein component (a) additionally comprises a glycidyl ether epoxy that is selected from the group consisting of bisphenol A-based glycidyl ether, a bisphenol S-based glycidyl ether, and a bisphenol F-based glycidyl ether.
5. The liquid radiation curable composition for additive fabrication of claim 4 , wherein the iodonium salt cationic photoinitiator is selected from the group consisting of (4-methylphenyl)[4-(2-methylpropyl) phenyl]-, hexafluorophosphate, [4-(1-methylethyl)phenyl](4-methylphenyl)-, tetrakis(pentafluorophenyl)borate(1-), (Bis(4-dodecylphenyl)iodonium hexaflurorantimonate), and (Bis(4-tert-butylphenyl)iodonium hexafluorophosphate).
6. The liquid radiation curable composition for additive fabrication of claim 5 , wherein the photosensitizer is a thioxanthone.
7. The liquid radiation curable composition for additive fabrication of claim 6 , wherein the thioxanthone is further selected from the group consisting of chloropropoxythioxanthones and isopropylthioxanthones.
8. The liquid radiation curable composition for additive fabrication of claim 7 , wherein the (d) first reductant for reducing component (b) is represented by the following formula (IV):
wherein Ar 1 , is a substituted or unsubstituted aromatic group, R 1 is Ar 1 or a C 2 -C 20 aliphatic chain, and R 2 is R 1 or contains one or more substituted or unsubstituted acyl phenyl groups.
9. The liquid radiation curable composition for additive fabrication of claim 8 , wherein the free-radical photoinitiator is not optional and is a hydroxycyclohexyl phenyl ketone.
10. The liquid radiation curable composition for additive fabrication of claim 9 , wherein the second reductant possessing an electron-donating substituent attached to a vinyl group (g) is selected from the group consisting of vinyl ethers, vinyl esters, vinyl thioethers, n-vinyl carbazoles, n-vinyl pyrollidones, n-vinyl caprolactams, allyl ethers, and vinyl carbonates.
11. The liquid radiation curable composition for additive fabrication of claim 10 , wherein the second reductant possessing an electron-donating substituent attached to a vinyl group (g) is a vinyl ether.
12. The liquid radiation curable composition for additive fabrication of claim 10 , wherein the second reductant possessing an electron-donating substituent attached to a vinyl group (g) is multifunctional.
13. The liquid radiation curable composition for additive fabrication of claim 1 , wherein the cycloaliphatic epoxide T 95 value of the composition is less than 55 seconds, the cycloaliphatic epoxide plateau conversion of the composition is greater than 30%, the oxetane T 95 value of the composition is less than 45 seconds, and the oxetane plateau conversion of the composition is greater than 33%.
14. The liquid radiation curable composition for additive fabrication of claim 13 , wherein the cycloaliphatic epoxide T 95 value of the composition is from 49 to 55 seconds, the cycloaliphatic epoxide plateau conversion of the composition is from 30% to 45%, the oxetane T 95 value of the composition is from 22 to 45 seconds, and the oxetane plateau conversion of the composition is from 33% to 60%.
15. The liquid radiation curable composition for additive fabrication of claim 12 , wherein the cycloaliphatic epoxide T 95 value of the composition is less than 55 seconds, the cycloaliphatic epoxide plateau conversion of the composition is greater than 30%, the oxetane T 95 value of the composition is less than 45 seconds, and the oxetane plateau conversion of the composition is greater than 33%.
16. The liquid radiation curable composition for additive fabrication of claim 15 , wherein the cycloaliphatic epoxide T 95 value of the composition is from 49 to 55 seconds, the cycloaliphatic epoxide plateau conversion of the composition is from 30% to 45%, the oxetane T 95 value of the composition is from 22 to 45 seconds, and the oxetane plateau conversion of the composition is from 33% to 60%.
17. The composition according to claim 1 , wherein, relative to the weight of the entire composition,
the cationically polymerizable component (a) is present from 25 to 65 wt. %; and
the free-radically polymerizable component (e) is present from 8 to 50 wt. %.
18. The composition according to claim 17 , wherein, relative to the weight of the entire composition, the photosensitizer component (c) is present from 0.1 to 2 wt. %.
19. The composition according to claim 18 , wherein, relative to the weight of the entire composition,
the first reductant (d) is present from 2 to 6 wt. %; and
the second reductant (g) is present from 1 to 10 wt. %.
20. The composition according to claim 19 , wherein
the iodonium salt cationic photoinitiator component (b) possesses an absorbance of less than 0.01 at 400 nm; and
wherein the photosensitizer component (c) comprises a compound according to the following formula (V):
wherein R contains an aliphatic chain from C 1 -C 20 .