Photocurable compositions and methods for 3D printing using them
The present disclosure relates generally to photocurable compositions and methods for continuously forming a three-dimensional body from these compositions. More particularly, the present disclosure relates to photocurable compositions comprising a mixture of polysiloxanes capable of being dually cured, i.e., first by UV radiation followed by thermal treatment, or being cured by UV radiation. In one aspect, the disclosure provides a photocurable composition, including: a first polysiloxane comprising at least two acrylate or methacrylate groups per molecule; a second polysiloxane containing at least one (e.g., at least two) Si—H group per molecule; a third polysiloxane containing at least one (e.g., at least two) reactive aliphatic ethylene group per molecule; a free radical photoinitiator in an amount of about 0.01 to about 10 weight % based on the total weight of (meth)acrylate-containing polysiloxane in the composition; and a hydrosilylation catalyst in an amount of about 0.001 to about 10 weight % hydride-containing polysiloxane and vinyl-containing polysiloxane in the composition.
1. A photocurable composition, comprising:
a first polysiloxane comprising at least about two acrylate or methacrylate groups per molecule, wherein the first polysiloxane is present in an amount of about 7 wt % to about 50 wt %;
a second polysiloxane containing at least one Si—H group per molecule, wherein the second polysiloxane is present in an amount of about 10 wt % to about 60 wt %;
a third polysiloxane containing at least one reactive aliphatic ethylene group that is not a (meth)acrylate per molecule, wherein the third polysiloxane is present in an amount of about 10 wt % to about 60 wt %, wherein each reactive aliphatic ethylene group of the third polysiloxane is not a (meth)acrylate;
a free radical photoinitiator in an amount of about 0.01 to about 10 weight % based on the total weight of (meth)acrylate-containing polysiloxane in the composition; and
a hydrosilylation catalyst in an amount of about 0.001 to about 10 weight % based on the total weight of hydride-containing polysiloxane and vinyl-containing polysiloxane in the composition.
2. A photocurable composition of claim 1 , wherein the first polysiloxane is poly(dimethylsiloxane-co-(methacryloxypropyl)methylsiloxane) or methacryloxypropyl terminated poly(dimethylsiloxane).
3. A photocurable composition of claim 1 , wherein the second polysiloxane has at least 1.75 Si—H groups per molecule.
4. A photocurable composition of claim 1 , wherein the third polysiloxane has at least 1.75 reactive aliphatic ethylene groups per molecule.
5. A photocurable composition of claim 1 , wherein the composition further comprises a fourth polysiloxane comprising at least about one aliphatic ethylene group and at least about one Si—H group per molecule having a molecular weight of less than about 100,000 g/mol.
6. A photocurable composition of claim 1 , further comprising one or more monofunctional reactive diluents in the photocurable composition, e.g., in an amount up to about 30 wt %, or up to about 20 wt % of the composition.
7. A photocurable composition of claim 1 , wherein the photoinitiator includes a first photoinitiator having an absorption at least 5 times that of a second photoinitiator at 380 nm.
8. A photocurable composition of claim 1 , comprising TPO as a first photoinitiator and DMAPA as a second photoinitiator.
9. A photocurable composition of claim 1 , wherein the photoinitiator is present in an amount of about 0.2 to about 2 weight % based on the total weight of (meth)acrylate-containing polysiloxane in the composition.
10. A photocurable composition of claim 1 , containing no more than 0.2 wt % of phosphorus-containing photoinitiators and sulfur-containing photoinitiators.
11. A photocurable composition of claim 1 , further comprising a thermal peroxide initiator.
12. A photocurable composition of claim 1 , wherein the hydrosilylation catalyst is a platinum catalyst.
13. A photocurable composition of claim 1 , wherein the first polysiloxane, the second polysiloxane, the third polysiloxane, any fourth polysiloxane, any reactive diluent, any filler, the photoinitiator, and the hydrosilylation catalyst are present in the composition in a total amount of at least 90 wt % of the composition.
14. A photocurable composition of claim 1 , wherein the molar ratio of Si—H to reactive aliphatic ethylene in the photocurable composition is in the range of 3:2 to 2:3.
15. A photocurable composition of claim 1 , having a viscosity of less than about 10,000 cSt at 25° C.
16. A photocurable composition of claim 1 , wherein the first polysiloxane is present in the composition in an amount in the range of about 20 wt % to about 80 wt %; and the second polysiloxane and the third polysiloxane are present in the composition in a total amount in the range of about 20 wt % to about 80 wt %.
17. A photocurable composition of claim 1 , wherein the hydrosilylation catalyst is a thermally-activated hydrosilylation catalyst and is not a light-activated hydrosilylation catalyst.
18. A photocurable composition, comprising:
a first polysiloxane comprising at least about two acrylate or methacrylate groups per molecule; wherein the first polysiloxane is present in an amount of about 10 wt % to about 50 wt %;
a second polysiloxane containing at least one Si—H group per molecule, wherein the second polysiloxane is present in an amount of about 1 wt % to about 80 wt %;
a third polysiloxane containing at least one reactive aliphatic ethylene group that is not a (meth)acrylate per molecule, wherein the third polysiloxane is present in an amount of about 1 wt % to about 80 wt %;
a fourth polysiloxane comprising at least about one aliphatic ethylene group and at least about one Si—H group per molecule having a molecular weight of less than about 100,000 g/mol, wherein the fourth polysiloxane is present in an amount of about 1 wt % to about 80 wt %;
a free radical photoinitiator in an amount of about 0.01 to about 10 weight % based on the total weight of (meth)acrylate-containing polysiloxane in the composition; and
a hydrosilylation catalyst in an amount of about 0.001 to about 10 weight % based on the total weight of hydride-containing polysiloxane and vinyl-containing polysiloxane in the composition.
19. A photocurable composition of claim 18 , wherein the fourth polysiloxane is present in an amount of about 10 wt % to about 80 wt %.
20. A method of forming a body comprising
providing a photocurable composition according to claim 1 ; and
curing the photocurable composition with actinic radiation to form a photocured three-dimensional body, then
curing the photocured three-dimensional body with heat to form a heat-cured three-dimensional body.