Method and composition for reducing waste in photo-imaging applications
Waste reduction, including hazardous waste reduction in photoimaging processes can be accomplished by improving diffusional resolution of cationic curable compositions. The addition of fluorinated polymers including fluorinated surfactants provides improved diffusional resolution in cationic and/or radical based photoimaging formulations allowing for image accuracy improvements, and reduced product and process waste quantity and disposal cost. These fluorinated surfactants also allow for increased cure speed, and non-hazardous constituent formulations that result in less wasted material and time.
1. A method of forming a three-dimensional article via stereolithography comprising the steps of:
(1) coating a layer of a composition onto a surface, said composition comprising
[a] a single cationic photoinitiator, said cationic photoinitiator being (tolylcumyl)iodonium tetrakis(pentafluorophenyl)borate,
[b] an epoxide,
[c] a photosensitizer component having the following chemical formula:
wherein R 1 -R 14 are independently H or C 1 -C 8 saturated or unsaturated, branched or unbranched, substituted or unsubstituted hydrocarbyl; and
[d] a free radical photoinitiator component that is different than the photosensitizer component;
(2) exposing the layer imagewise to actinic radiation to form an imaged cross-section, wherein the actinic radiation provides sufficient exposure to cause substantial curing of the layer in the exposed areas;
(3) coating a layer of said composition onto the previously exposed imaged cross-section;
(4) exposing the layer from step (3) imagewise to actinic radiation to form an additional imaged cross-section, wherein the radiation is of sufficient intensity to cause substantial curing of the layer in the exposed areas and to cause adhesion to the previously exposed imaged cross-section; and
(5) repeating steps (3) and (4) a sufficient number of times in order to build up a three-dimensional article.
2. The method of claim 1 , wherein said composition is antimony-free.
3. The method of claim 1 , wherein said composition further comprises an acrylate.
4. The method of claim 1 , wherein said photosensitizer comprises 4-benzoyl-4-methyldiphenyl sulfide.
5. The method of claim 1 , wherein the free radical photoinitiator component that is different than the photosensitizer component is 2-Hydroxy-2-2 methyl-1-phenyl-propan-1-one.
6. The method of claim 1 , wherein said composition further comprises an oxetane.
7. The method of claim 1 , wherein said composition further comprises a photoacid diffusion inhibitor.
8. The method of claim 7 , wherein said photoacid diffusion inhibitor comprises a fluorinated polymer.
9. The method of claim 7 , wherein said photoacid diffusion inhibitor comprises a fluorinated surfactant.
10. The method of claim 1 , wherein said composition further comprises a photoacid diffusion inhibitor comprising a fluorinated polymer surfactant without a linking ester group.
11. The method of claim 10 , wherein said photoacid diffusion inhibitor is 1.0 wt. % or less of said composition.
12. The method of claim 5 , wherein the ratio by weight, relative to the total composition, of the free-radical photoinitiator component [d] to the photosensitizer component [c] is greater than 9:1.
13. The method of claim 10 , wherein said composition has an improved diffusional resolution over an identical composition exclusive of the photoacid diffusion inhibitor.
14. The method of claim 10 , wherein said composition further comprises glycidyl epoxide monomers.
15. The method of claim 10 , wherein said photoacid diffusion inhibitor contains fluorinated moieties having the following formula C k F m wherein m has a value of 3-5 and k has a value of 1 or 2.
16. The method of claim 10 , wherein said moieties are part of a repeating group that is repeated at least 5 times.
17. The method of claim 10 , wherein, said photosensitizer comprises 4-benzoyl-4-methyldiphenyl sulfide.