Liquid radiation curable resins capable of curing into layers with selective visual effects and methods for the use thereof
View Patent ↗The invention relates to a method for forming a liquid radiation curable resin capable of curing into a solid upon irradiation comprising at least one thermally sensitive visual effect initiator. The liquid radiation curable resin is capable of curing into three-dimensional articles having selective visual effects. The resulting three-dimensional articles possess excellent color and/or transparency stability and excellent mechanical properties.
1. A method of forming a three-dimensional article having at least one selectively colored and/or transparent region comprising subjecting a liquid radiation curable resin comprising at least one thermally sensitive visual effect initiator having an activation temperature to appropriate imaging radiation to form a three-dimensional article layer by layer, while simultaneously selectively controlling the temperature of the liquid radiation curable resin so that at least one portion of the liquid radiation curable resin is at or above the activation temperature of the thermally sensitive visual effect initiator to thereby form the at least one selectively colored and/or transparent region of the three-dimensional article; wherein the thermally sensitive visual effect initiator comprises at least one thermally sensitive transparency modifier which further comprises thermally expandable microspheres; wherein the temperature of the liquid radiation curable resin composition is selectively controlled by selectively irradiating the liquid radiation curable resin composition with at least two different doses of light, and wherein a single light source is used to create the at least two different doses of light.
2. The method of claim 1 further comprising the steps of:
(a) forming a layer of liquid radiation curable resin;
(b) selectively curing the layer of liquid radiation curable resin while selectively controlling the temperature of the liquid radiation curable resin thereby forming a cured solid layer with at least one selectively colored and/or transparent region;
(c) repeating steps (a) and (b) a sufficient number of times in order to build up a three-dimensional article.
3. The method of claim 1 wherein the liquid radiation curable resin comprises a free radical polymerizable component and a photoinitiating system capable of initiating free radical polymerization.
4. The method of claim 1 wherein the liquid radiation curable resin comprises a cationic polymerizable component and a photoinitiating system capable of initiating cationic polymerization.
5. The method of claim 1 wherein the thermally sensitive visual effect initiator is present in an amount, relative to the total weight of the liquid radiation curable resin, from about 0.005 wt % to about 5 wt %.
6. The method of claim 1 wherein the at least one thermally sensitive visual effect initiator comprises at least one thermochromic component.
7. The method of claim 6 wherein the thermochromic component comprises a thermally sensitive ink contained in a microcapsule.
8. The method of claim 1 wherein the thermally sensitive visual effect does not undergo any visual color or transparency change in response to an acid produced during polymerization of the liquid radiation curable resin.
9. The method of claim 1 wherein the at least one thermally sensitive visual effect initiator has a locking temperature and the temperature of the liquid radiation curable resin is selectively controlled so that at least one portion of the liquid radiation curable resin is at or above the locking temperature of the at least one thermally sensitive visual effect initiator.
10. The method of claim 1 wherein the liquid radiation curable resin comprises at least two thermally sensitive visual effect initiators.
11. The method of claim 10 wherein the at least two thermally sensitive visual effect initiators have different locking temperatures.
12. The method of claim 1 , wherein the single light source used to create the at least two different doses of light is a light source which emits radiation from 300-475 nm.
13. The method of claim 1 , wherein the at least one thermally sensitive visual effect initiator having an activation temperature to appropriate imaging radiation is present in an amount, relative to the total weight of the liquid radiation curable resin, from 0.005 wt % to 0.5 wt %.
14. The method of claim 6 , wherein the single light source used to create the at least two different doses of light is a light source which emits radiation from. 300-475 nm.
15. The method of claim 14 , wherein the single light source used to create the at least two different doses of light is a solid state laser.