3D printing method utilizing a photocurable silicone composition

1. A method of forming a three-dimensional (3D) article, said method comprising the steps of:

I) printing a first photocurable silicone composition with a 3D printer to form a layer;

II) irradiating the layer with an energy source to form an at least partially cured layer;

III) printing a second photocurable silicone composition on the at least partially cured layer with the 3D printer to form a subsequent layer; and

IV) irradiating the subsequent layer with the energy source to form an at least partially cured subsequent layer; and

V) optionally, repeating steps III) and IV) with independently selected photocurable silicone compositions for any additional layer(s) to form the 3D article;

wherein the first and second photocurable silicone compositions are the same as or different from one another;

wherein the photocurable silicone composition(s) is(are) free of acrylate or epoxy functionality; and

wherein at least one of the photocurable silicone compositions comprises:

A) an organosilicon compound having an average of at least two silicon-bonded ethylenically unsaturated groups per molecule, wherein:

i) ethylenically unsaturated moieties of the silicon-bonded ethylenically unsaturated groups are separated by at least four atoms, and/or

ii) component A) also has at least one silicon-bonded phenyl group per molecule and a silicon atom bearing an ethylenically unsaturated group and a silicon atom bearing a phenyl group are separated by only an oxygen atom;

B) an organosilicon compound having an average of at least two silicon-bonded hydrogen atoms per molecule in an amount sufficient to cure the photocurable silicone composition; and

C) a catalytic amount of a photoactivated hydrosilylation catalyst; and

D) optionally, a filler.

2. The method as set forth in claim 1 , wherein the 3D printer is selected from the group of powder-bed 3D printers, inkjet 3D printers, extrusion 3D printers, light-polymerized 3D printers, or combinations thereof.

3. A method of forming a three-dimensional (3D) article, said method comprising the steps of:

I) printing a first photocurable silicone composition with a 3D printer to form a layer;

II) irradiating the layer with an energy source to form an at least partially cured layer;

III) printing a second photocurable silicone composition on the at least partially cured layer with the 3D printer to form a subsequent layer; and

IV) irradiating the subsequent layer with the energy source to form an at least partially cured subsequent layer; and

V) optionally, repeating steps III) and IV) with independently selected photocurable silicone compositions for any additional layer(s) to form the 3D article;

wherein the first and second photocurable silicone compositions are the same as or different from one another;

wherein the 3D printer comprises at least one of a powder-bed 3D printer, an extrusion 3D printer, or a light-polymerized 3D printer; and

wherein at least one of the photocurable silicone compositions comprises:

A) an organosilicon compound having an average of at least two silicon-bonded ethylenically unsaturated groups per molecule, wherein:

i) ethylenically unsaturated moieties of the silicon-bonded ethylenically unsaturated groups are separated by at least four atoms, and/or

ii) component A) also has at least one silicon-bonded phenyl group per molecule and a silicon atom bearing an ethylenically unsaturated group and a silicon atom bearing a phenyl group are separated by only an oxygen atom;

B) an organosilicon compound having an average of at least two silicon-bonded hydrogen atoms per molecule in an amount sufficient to cure the photocurable silicone composition; and

C) a catalytic amount of a photoactivated hydrosilylation catalyst; and

D) optionally, a filler.

4. The method as set forth in claim 1 , wherein the energy source emits at least one of ultraviolet (UV) radiation, infrared (IR) radiation, visible light, X-rays, gamma rays, or electron beams, alternatively at least UV radiation.

5. The method as set forth in claim 1 , wherein the photocurable silicone composition comprises:

A) the organosilicon compound having an average of at least two silicon-bonded ethylenically unsaturated groups per molecule, wherein ethylenically unsaturated moieties of the silicon-bonded ethylenically unsaturated groups are separated by at least four atoms.

6. The method as set forth in claim 1 , wherein the photocurable silicone composition comprises:

A) the organosilicon compound having an average of at least two silicon-bonded ethylenically unsaturated groups and at least one silicon-bonded phenyl group per molecule, wherein a silicon atom bearing an ethylenically unsaturated group and a silicon atom bearing a phenyl group are separated by only an oxygen atom.

7. The method as set forth in claim 5 , wherein component D) is present in an amount of at least about 5, alternatively at least about 25, alternatively at least about 50, alternatively at least about 75, parts by weight based on 100 parts by weight of the photocurable silicone composition.

8. The method as set forth in claim 1 , wherein the first and second photocurable silicone compositions are the same.

9. A 3D article formed according to the method as set forth in claim 1 .

10. A photocurable silicone composition for three-dimensional (3D) printing, said photocurable silicone composition comprising:

A) an organosilicon compound having an average of at least two silicon-bonded ethylenically unsaturated groups per molecule;

B) an organosilicon compound having an average of at least two silicon-bonded hydrogen atoms per molecule in an amount sufficient to cure said photocurable silicone composition; and

C) a catalytic amount of a photoactivated hydrosilylation catalyst; and

D) optionally, a filler;

wherein at least one of the following conditions is true:

I) ethylenically unsaturated moieties of said silicon-bonded ethylenically unsaturated groups of component A) are separated by at least four atoms; or

II) component A) also has at least one silicon-bonded phenyl group per molecule and a silicon atom bearing an ethylenically unsaturated group and a silicon atom bearing a phenyl group of component A) are separated by only an oxygen atom.

11. The composition as set forth in claim 10 , wherein component B) is selected from the group of organohydrogensiloxanes, organohydrogensilanes, or combinations thereof.

12. The composition as set forth in claim 10 , wherein:

i) component A) is selected from the group of polysiloxanes, polysilanes, polycarbosilanes, polycarbosiloxanes, or combinations thereof;

ii) said silicon-bonded ethylenically unsaturated groups of component A) are alkenyl groups, alternatively are vinyl groups; or

iii) both i) and ii).

13. The composition as set forth in claim 10 , wherein component A) is a polysiloxane of average formula A1):

(R 1 R 2 2 SiO 1/2 ) a (R 3 2 SiO 2/2 ) b (R 4 SiO 3/2 ) c (SiO 4/2 ) d   A1);

where each of R 1 , R 2 , R 3 , and R 4 is an independently selected substituted or unsubstituted hydrocarbyl group, 0≤a≤0.80, 0≤b≤1.00, 0≤c≤0.85, and 0≤d≤0.85, provided that a, b, c, and d are not simultaneously 0 and a+b+c+d=1.

14. The composition as set forth in claim 13 , wherein:

i) component A) has a viscosity less than 1,000,000 centistokes at 25° C.;

ii) 0.10≤a≤0.80, 0≤b≤1.00, 0<c≤0.75, and 0≤d≤0.50; or

iii) both i) and ii).

15. The composition as set forth in claim 13 , wherein:

i) R 1 is an alkenyl group, alternatively a vinyl group, a=0.75 or 0.67, c=0.25 or 0, b=0 or 0.33, and d=0; and/or

ii) R 2 is a methyl group; and/or

iii) R 3 is a methyl group; and/or

iv) R 4 is a phenyl group.

16. The composition as set forth in claim 10 , wherein component D) is present in an amount of at least about 5, alternatively at least about 25, alternatively at least about 50, alternatively at least about 75, parts by weight based on 100 parts by weight of the photocurable silicone composition.

17. The composition as set forth in claim 10 , further defined as a multi-part photocurable silicone composition, wherein component A) is in a first part, component B) is in a second part separate from said first part, and component C) is in said first part, in said second part, and/or in a third part separate from said first and second parts.

18. A 3D article comprising the reaction product of the composition as set forth in claim 10 .

19. The method as set forth in claim 1 , wherein component D) is present in an amount of at least about 5, alternatively at least about 25, alternatively at least about 50, alternatively at least about 75, parts by weight based on 100 parts by weight of the photocurable silicone composition.

20. The method as set forth in claim 3 , wherein component D) is present in an amount of at least about 5, alternatively at least about 25, alternatively at least about 50, alternatively at least about 75, parts by weight based on 100 parts by weight of the photocurable silicone composition.