CURABLE SILICONE COMPOSITION

Abstract

A curable silicone composition is described. Also described, is a method of producing a three-dimensional (3D) printed article with a curable silicone composition involving epoxy-related photocuring and hydrosilylation curing. In exemplary embodiments, the resulting three-dimensional (3D) printed article thus formed and the curable silicone composition or the resulting three-dimensional (3D) printed article can be used in electronics applications and/or in 3D printing.

Claims

1. A method of producing a three-dimensional (3D) printed article, the method comprising the steps of: (i) providing a curable silicone composition, comprising: A. at least one organopolysiloxane comprising, per molecule, at least two alkenyl or alkynyl groups bonded to silicon atoms; B. at least one organohydrogenopolysiloxane comprising, per molecule, at least two hydrogen atoms bonded to silicon atoms, C. at least one hydrosilylation catalyst; D. at least one epoxy-functional organosilicon compound; E. at least one cationic photoinitiator; F. optionally, at least one filler and/or at least one silicone resin; G. optionally, at least one hydrosilylation inhibitor, and H. optionally at least one photosensitizer, (ii) printing said curable silicone composition with a 3D printer to form a printed composition, (iii) photopolymerizing at least part of the total number of epoxy groups of the printed composition while printing to provide an at least partially solidified layer, (iv) optionally, repeating one or more times steps (ii) and (iii) onto said at least partially solidified layer previously obtained until a desired shape is obtained, and (iv) allowing hydrosilylation curing to continue until said at least partially solidified layer(s) becomes a solidified layer(s), and hence obtaining said 3D printed article.

2. The method according to claim 1, wherein the curable silicone composition comprises: (a) in addition to the components A and B, or in place of the components A and B, at least one organosilicon compound comprising, per molecule, at least two alkenyl or alkynyl groups bonded to silicon atoms and at least two hydrogen atoms bonded to silicon atoms; (b) in addition to the components A and D, or in place of the components A and D, at least one organosilicon compound comprising, per molecule, at least two alkenyl or alkynyl groups bonded to silicon atoms and at least one epoxy function; (c) in addition to the components B and D, or in place of the components B and D, at least one organosilicon compound comprising, per molecule, at least two hydrogen atoms bonded to silicon atoms and at least one epoxy function; or (d) in addition to the components A, B and D, or in place of the components A, B and D, at least one organosilicon compound comprising, per molecule, at least two alkenyl or alkynyl groups bonded to silicon atoms, at least two hydrogen atoms bonded to silicon atoms and at least one epoxy function.

3. The method according to claim 1, wherein the cationic photoinitiator E is a Brönsted acid or a Lewis acid.

4. The method according to claim 3, wherein the cationic photoinitiator E is an iodonium borate having, for its cationic part at the level of its aromatic nuclei, alkyl radical groups having from 10 to 30 carbon atoms, which is used in combination with a hydrogen donor chosen from a Guerbet alcohol.

5. The method according to claim 1, wherein the filler F is mineral filler.

6. The method according to claim 1, wherein the filler F is used in an amount from 0.01% to 90% by weight, relative to all the components of the composition.

7. The method according to claim 1, wherein the method employs the silicone resin in an amount from 0.01% to 90% by weight, relative to all the components of the composition.

8. The method according to claim 1, wherein the weight ratio of the organopolysiloxane A to the epoxy-functional organosilicon compound D is from 0.001 to 50.

9. The method according to claim 1, wherein the printing with the 3D printer is performed using an approach selected from the group consisting of Extrusion 3D printing, UV-Stereolithography (SLA), UV-Digital Light processing (DLP), Continuous Liquid Interface Production (CLIP), Inkjet Deposition and combinations thereof.

10. A three-dimensional (3D) printed article formed in accordance with the method of claim 1.

11. A method of a using a curable silicone composition in an electronics application, the method comprising employing the curable silicone composition according to claim 1 in the electronics application.

12. The method according to claim 1, wherein the at least one organohydrogenpolysiloxane comprises, per molecule, at least three hydrogen atoms bonded to silicon atoms.

13. The method according to claim 1, wherein the at least one hydrosilylation catalyst is a metal belonging to the platinoids.

14. The method according to claim 13, wherein the metal is platinum or rhodium.

15. The method according to claim 1, wherein the at least one hydrosilylation catalyst is selected from the group consisting of a platinum compound, a chloroplatinic acid, a platinum complex, a platinum/vinyl siloxane complex, a Karstedt catalyst comprising a platinum complex with divinyltetramethyldisiloxane as a ligand and mixtures thereof.

16. the method according to claim 1, wherein the at least partially solidified layer(s) become the solidified layer(s) by heating at a temperature in a range of from 40° C. to 190° C.

17. The method according to claim 3, wherein the Brönsted acid is an onium salt.

18. The method according to claim 17, wherein the onium salt is selected from the group consisting of diaryliodonium salt, aryldiazonium salt, alkoxypyridinium salt, triarylsulfonium salt, sulfonium salt and combinations thereof.

19. The method according to claim 3, wherein the Lewis acid is an organometallic salt.

20. The method according to claim 3, wherein the cationic photoinitiator E is selected from the group consisting of diaryliodonium salt, aryldiazonium salt, alkoxypyridinium salt, triaryl sulfonium salt, sulfonium salt and combinations thereof.

21. The method according to claim 20, wherein the cationic photoinitiator E is diaryliodonium salt.

22. The method according to claim 5, wherein the mineral filler is selected from the group consisting of colloidal silica, powder of fumed silica, powder of precipitated silica and mixtures thereof.

23. The method according to claim 6, wherein the amount of the filler F is from 0.1% to 80% by weight.

24. The method according to claim 23, wherein the amount of the filler F is from 0.5% to 50% by weight.

25. The method according to claim 7, wherein the amount of the silicone resin is from 0.1% to 80% by weight.

26. The method according to claim 25, wherein the amount of the silicone resin is from 0.5% to 50% by weight.

27. The method according to claim 8, wherein the weight ratio of the organopolysiloxane A to the epoxy-functional organosilicon compound D is from 0.1 to 40.

28. The method according to claim 27, wherein the weight ratio is from 0.1 to 30.

29. A method of using a three-dimensional (3D) printed article in a 3D printing application, the method comprising employing the 3D printed article according to claim 10 in the 3D printing application.

Description

DESCRIPTION OF THE FIGURES

[0176] FIG. 1 shows the transparency results of the products obtained after curing of the compositions according to three examples of the invention.

MODE OF CARRYING OUT THE INVENTION

[0177] Other advantages and features of the present invention will appear on reading the following examples that are given by way of illustration and that are in no way limiting.

EXAMPLES

[0178] Raw materials used in the examples are listed in the following table 1:

TABLE-US-00001 TABLE 1 Raw materials Chemical description or structure A-1 Vinyl terminated Polydimethylsiloxane, viscosity: 1500 mPa .Math. s, vinyl content: 0.26 wt % A-2 Vinyl terminated Polydimethylsiloxane, viscosity: 100000 mPa .Math. s, vinyl content: 0.08 wt % A-3 Vinyl terminated Polydimethylsiloxane, viscosity: 60000 mPa .Math. s, vinyl content: 0.08 wt % A-4 Vinyl terminated Polydimethylsiloxane, viscosity: 3500 mPa .Math. s, vinyl content: 0.2 wt % B-1 Poly(methylhydrogeno)(dimethyl)siloxane with end-chain (α/ω) SiH groups, viscosity: 160 mPa .Math. s, SiH content: 0.8 wt % B-2 Poly(methylhydrogeno)(dimethyl)siloxane with SiH groups in-chain and end-chain (α/ω), viscosity: 25 mPa .Math. s, SiH content: 20 wt % B-3 Poly(methylhydrogeno)(dimethyl)siloxane with SiH groups in-chain and end-chain (α/ω), viscosity: 300 mPa .Math. s, SiH content: 4.75 wt % C-1 Pt catalyst: Platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane (Pt content: 10 wt %) D-1 Epoxy-containing Polydimethylsiloxane, viscosity: 5500 mPa .Math. s, epoxy content: 2.7 wt % [00011] in which p = 310; q = 4.5 D-2 Epoxy-containing Polydimethylsiloxane, viscosity: 45 mPa .Math. s, epoxy content: 12.65 wt % [00012] in which n = 22 D-3 Epoxy-containing Polydimethylsiloxane, viscosity: 465 mPa .Math. s, epoxy content: 16.1 wt % [00013] in which a = 11; b = 85, Me = methyl D-4 Epoxy-containing Polydimethylsiloxane, viscosity: 350 mPa .Math. s, epoxy content: 11.25 wt % [00014] in which a = 7.5; b = 80, Me = methyl D-5 Epoxy-containing Polydimethylsiloxane, viscosity: 765 mPa .Math. s, epoxy content: 2.65 wt % [00015] in which a = 220; b = 2.5, Me = methyl E-1 iodonium borate salt diluted in Guerbet alcohol, CAS NO.: 1115251-57-4 E-2 Diphenyliodonium hexafluorophosphate CAS NO.: 58109-40-3 F-1 Treated silica, CAS NO: 68988-89-6 F-2 Alumina F-3 Vinyl-containing siloxane resin MD.sup.ViQ, vinyl content: 1.88 wt % G-1 Ethynylcyclohexanol, CAS NO.: 78-27-3 H-1 Photosensitizer: mixture of 2-isopropylthioxanthone (CAS NO.: 5495-84-1) and 4- isopropylthioxanthone, (CAS NO.: 83846-86-0) I-1 (CAS NO.: 83846-86-0) Vinyltrimethoxysilane CAS NO.: 2768-02-7 I-2 (3-Glycidyloxypropyl) Trimethoxysilane CAS NO.: 2530-83-8 I-3 the reaction product obtained by condensation of the following two materials: [00016] [00017] in which x = 0~10000, and y = 0~10000. I-4 Polydisiloxane with epoxy group and SiH viscosity: 14 mPa .Math. s, SiH content: 38.5 wt % CAS NO.: 1337988-64-3

TABLE-US-00002 TABLE 2-a Formulas and test results of curable silicone compositions example 1 example 2 example 3 example 4 example 5 example 6 example 7 example 8 example 9 Raw materials A-1 32.26 80.6 43.98 43.95 44.68 35.66 23.94 83.79 74.7 A-2 0 0 0 0 0 0 0 0 0 B-1 4.61 4.24 3.5 3.5 2 2.47 1.77 3.53 3.53 B-2 0 0 1.5 1.5 0 1.06 0.76 1.51 1.51 B-3 2.76 1.81 0 0 2 0 0 0 0 C-1 0.0092 0.016 0.016 0.016 0.016 0.016 0.016 0.016 0.016 D-1 46.08 3 40 39.99 40 50 62.59 11 20 D-2 0 0 0 0 0 0 0 0 0 D-3 0 0 0 0 0 0 0 0 0 D-4 0 0 0 0 0 0 0 0 0 D-5 0 0 0 0 0 0 0 0 0 E-1 0.46 0.03 0.4 0.4 0.4 0.5 0.63 0.11 0.2 F-1 13.82 10.26 10.17 10.16 10.17 10.26 10.26 0 0 G-1 0.0092 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 H-1 0 0 0 0.05 0 0 0 0 0 I-1 0 0 0.2 0.2 0 0 0 0 0 I-2 0 0 0.2 0.2 0 0 0 0 0 I-3 0 0 0 0 0.2 0 0 0 0 W 0 0 0 0 0.5 0 0 0 0 TOTAL 100 100 100 100 100 100 100 100 100 SiH/Si-alkenyl 1.27 1.54 1.7 1.66 1.9 1.77 1.68 1.41 1.8 (mole ratio) Alkenyl-sioxane/ 0.7 26.8 1.1 1.1 1.1 0.71 0.38 7.6 3.7 epoxy - siloxane (weight ratio) Test results Viscosity, 25° C., 89000 (6#, 26000 (6#, 22900 (6#, 36000 (6#, 25000 (6#, 24500 (6#, 18800 (6#, 1700 (3#, 2000 (3#, mPa .Math. s 20 rpm) 20 rpm) 20 rpm) 10 rpm) 20 rpm) 20 rpm) 20 rpm) 20 rpm) 20 rpm) Status after UV curing, shape shape shape shape shape shape shape shape shape UV curing 30 sec figuration figuration figuration figuration figuration figuration figuration figuration figuration Hardness, 26 NA 15 20 15 20 31 NA NA Shore A tear UV curing 0.6 NA 0.58 0.92 0.51 0.59 0.87 NA NA strength, 30 sec + N/mm 80° C. × Tensile 30 min 0.8 NA 0.5 0.37 0.54 0.51 0.41 NA NA strength, Mpa Elongation at 70 NA 81 63 64 62 41 NA NA break, % Bath life 3 160 >360 170 stability at 20° C. (hours) Bath life 2 50 94 51 stability at 30° C. (hours) example 10 example 11 example 12 example 13 example 14 example 15 example 16 Raw materials A-1 45.92 17.88 23.94 35.66 35.66 35.66 35.66 A-2 0 0 11.72 0 0 0 0 B-1 2.47 0.88 2.47 2.47 2.47 2.47 2.47 B-2 1.06 0.38 1.06 1.06 1.06 1.06 1.06 B-3 0 0 0 0 0 0 0 C-1 0.016 0.016 0.016 0.016 0.016 0.016 0.016 D-1 50 80 50 0 0 0 0 D-2 0 0 0 50 0 0 0 D-3 0 0 0 0 50 0 0 D-4 0 0 0 0 0 50 0 D-5 0 0 0 0 0 0 50 E-1 0.5 0.8 0.5 0.5 0.5 0.5 0.5 F-1 0 0 10.26 10.26 10.26 10.26 10.26 G-1 0.04 0.04 0.04 0.04 0.04 0.04 0.04 H-1 0 0 0 0 0 0 0 I-1 0 0 0 0 0 0 0 I-2 0 0 0 0 0 0 0 I-3 0 0 0 0 0 0 0 W 0 0 0 0 0 0 0 TOTAL 100 100 100 100 100 100 100 SiH/Si-alkenyl 1.79 1.65 1.77 1.77 1.77 1.77 1.77 (mole ratio) Alkenyl-sioxane/ 0.92 0.22 0.71 0.71 0.71 0.71 0.71 epoxy - siloxane (weight ratio) Test results Viscosity, 25° C., 3150 (3#, 4900 (3#, 50000 (6#, 8600 (5#, 51500 (6#, 6190 (4#, 29200 (6#, mPa .Math. s 20 rpm) 20 rpm) 10 rpm) 20 rpm) 10 rpm) 20 rpm) 20 rpm) Status after UV curing, shape shape shape shape shape shape shape UV curing 30 sec figuration figuration figuration figuration figuration figuration figuration Hardness, 11 24 25 NA NA 37 20 Shore A tear UV curing 0.49 0.56 0.9 NA NA 1.9 2.6 strength, 30 sec + N/mm 80° C. × Tensile 30 min 0.056 0.38 0.48 NA NA 0.24 0.21 strength, Mpa Elongation 60 NA NA 73 at 50 56 55 break, % Bath life stability at 20° C. (hours) Bath life stability at 30° C. (hours)

TABLE-US-00003 TABLE 2-b Formulas and test results of curable silicone compositions example 17 example 18 example 19 example 20 example 21 example 22 Raw materials A-1 34.4 21.66 45.66 11.72 0 81.88 A-3 0 0 0 17.98 0 0 A-4 0 0 0 0 11.45 0 B-1 2.47 2.47 2.47 5.44 1.2 2.45 B-2 1.06 1.06 1.06 2.33 2.44 1.98 B-3 0 0 0 0 0 0 C-1 0.016 0.016 0.016 0.016 0.016 0.016 D-1 50 50 40 50 50 0 E-1 0 0.5 0.5 0.5 0.5 0.50 E-2 0.5 0 0 0 0 0 F-1 10.26 4.26 10.26 0 0 13.14 F-2 0 20 0 0 0 0 F-3 0 0 0 11.99 34.35 0 G-1 0.04 0.04 0.04 0.04 0.04 0.04 TOTAL 100 100 100 100 100 100 SiH/Si-alkenyl 1.77 3.14 1.46 1.75 1.69 1.55 (mole ratio) Alkenyl-siloxane/ 0.69 0.43 1.14 0.83 0.92 epoxy - siloxane (weight ratio) Test results Viscosity, 25° C., 25000 10250 28000 7320 5100 mPa .Math. s (6#, (6#, (6#, (4#, (4#, 20 rpm) 20 rpm) 20 rpm) 20 rpm) 20 rpm) Status after UV curing, Non-shape shape shape shape shape No shape UV curing 30 sec figuration figuration figuration figuration figuration figuration Hardness, UV curing, shape NA NA NA NA No shape Shore A 45 sec figuration figuration UV curing, NA NA 13 30 shore.OO 1 30 sec Hardness, NA 31 17 37 shore.OO 3 Shore A tear UV curing NA 0.72 0.45 0.5 0.51 strength, 30 sec + N/mm 80° C. × Tensile NA 0.56 0.36 0.17 0.077 strength, 30 min Mpa Elongation at NA 57 61 48 62 break, % Rate of 24% 19% 67% hardness change NA: mechanical property could not be tested.

[0179] In the table 2-b, hardnesses of samples are obtained by using different durometers such as Shore.A or Shore.OO. Conversion relationship of the two durometers can be seen in table 3 according to the standard ASTM D 2240 and DIN 53505.

[0180] In the table 2-a and 2-b, “shape figuration” means that after UV curing, the composition loses its fluidity due to the reaction, and thus be in the state of a gel or an elastomer.

TABLE-US-00004 TABLE 3 hardness conversion table Shore.OO Shore.A 45 5 55 10 62 15 70 20 76 25 80 30 83 35

Examples 1-2 are Prepared According to the Following Procedure

[0181] 46.08 parts of epoxy grafted polydimethylsiloxane oil D-1, with a viscosity equal to 5500 mPa.Math.s and comprising 2.7% by weight of epoxy groups, are added to 32.26 parts of vinyl terminated polydimethylsiloxane A-1 and 13.82 parts of F-1. The 0.0092 parts of inhibitor G-1 are added and then mixed sufficiently. 4.61 parts of a hydrogen-terminated polysiloxane oil B-1 and 2.76 parts of a hydrosiloxane oil B-3 are added and mixed, following with 0.46 parts of E-1 and 0.0092 parts of C-1 to obtain curable silicone composition in example 1. Example 2 is similarly prepared according to the above process via adjusting ratio of different raw materials.

Example 3 is Prepared According to the Following Procedure

[0182] 40.17 parts of epoxy grafted polydimethylsiloxane oil D-1, with a viscosity equal to 5500 mPa.Math.s and comprising 2.7% by weight of epoxy groups, are added to 44.15 parts of vinyl terminated polydimethylsiloxane A-1 and 10.21 parts of F-1. The 0.04 parts of inhibitor G-1 are added and then mixed sufficiently. 3.51 parts of a hydrogen-terminated polysiloxane oil B-1 and 1.5 parts of a hydrosiloxane oil B-2 are added and mixed, following with 0.2 parts of I-1 and 0.2 parts of I-2. Finally, and 0.016 parts of C-1 are added into polysilxoane mixture to obtain curable silicone composition in example 3.

Example 4 is Prepared According to the Following Procedure

[0183] 40.15 parts of epoxy grafted polydimethylsiloxane oil D-1, with a viscosity equal to 5500 mPa.Math.s and comprising 2.7% by weight of epoxy groups, are added to 44.13 parts of vinyl terminated polydimethylsiloxane A-1 and 10.21 parts of F-1. The 0.04 parts of inhibitor G-1 are added and then mixed sufficiently. 3.51 parts of a hydrogen-terminated polysiloxane oil B-1 and 1.5 parts of a hydrosiloxane oil B-2 are added and mixed, following with 0.2 parts of I-1 and 0.2 parts of I-2. Finally, 0.05 parts of H-1 and 0.016 parts of C-1 are added into polysilxoane mixture to obtain curable silicone composition in example 4.

Example 5 is Prepared According to the Following Procedure

[0184] 40 parts of epoxy grafted polydimethylsiloxane oil D-1, with a viscosity equal to 5500 mPa.Math.s and comprising 2.7% by weight of epoxy groups, are added to 44.68 parts of vinyl terminated polydimethylsiloxane A-1 and 10.17 parts of F-1. The 0.04 parts of inhibitor G-1 are added and then mixed sufficiently. 2 parts of a hydrogen-terminated polysiloxane oil B-1 and 2 parts of a hydrosiloxane oil B-3 are added and mixed, following with 0.2 parts of I-3 and 0.5 parts of I-4. Finally, 0.4 parts of E-1, and 0.016 parts of C-1 are added into polysilxoane mixture to obtain curable silicone composition in example 5.

Examples 6-7 are Prepared According to the Following Procedure

[0185] 50 parts of epoxy grafted polydimethylsiloxane oil D-1, with a viscosity equal to 5500 mPa.Math.s and comprising 2.7% by weight of epoxy groups, are added to 35.66 parts of vinyl terminated polydimethylsiloxane A-1 and 10.26 parts of F-1. The 0.04 parts of inhibitor G-1 are added and then mixed sufficiently. 2.47 parts of a hydrogen-terminated polysiloxane oil B-1 and 1.06 parts of a hydrosiloxane oil B-2 are added and mixed, following with 0.5 parts of E-1 and 0.016 parts of C-1 to obtain curable silicone composition in example 6. Example 7 is similarly prepared according to the above process via adjusting ratio of different raw materials.

Examples 8-11 are Prepared According to the Following Procedure

[0186] 11 parts of epoxy grafted polydimethylsiloxane oil D-1, with a viscosity equal to 5500 mPa.Math.s and comprising 2.7% by weight of epoxy groups, are added to 83.79 parts of vinyl terminated polydimethylsiloxane A-1. The 0.04 parts of inhibitor G-1 are added and then mixed sufficiently. 3.53 parts of a hydrogen-terminated polysiloxane oil B-1 and 1.51 parts of a hydrosiloxane oil B-2 are added and mixed, following with 0.11 parts of E-1 and 0.016 parts of C-1 to obtain curable silicone composition in example 8. Examples 9-11 are similarly prepared according to the above process via adjusting ratio of different raw materials.

Examples 12-16 are Prepared According to the Following Procedure

[0187] 50 parts of epoxy grafted polydimethylsiloxane oil D-1, with a viscosity equal to 5500 mPa.Math.s and comprising 2.7% by weight of epoxy groups, are added to 23.94 parts of vinyl terminated polydimethylsiloxane A-1, 11.72 parts of vinyl terminated polydimethylsiloxane A-2 and 10.26 parts of F-1. The 0.04 parts of inhibitor G-1 are added and then mixed sufficiently. 2.47 parts of a hydrogen-terminated polysiloxane oil B-1 and 1.06 parts of a hydrosiloxane oil B-2 are added and mixed, following with 0.5 parts of E-1 and 0.016 parts of C-1 to obtain curable silicone composition in example 12. Example 13-16 are similarly prepared according to the above process via adjusting ratio of different raw materials. Herein, in place of D-1 used in example 12, examples 13-16 respectively use D-2, D-3, D-4 and D-5 according to the ratios in the table 2-a.

Example 17 is Prepared According to the Following Procedure

[0188] 50 parts of epoxy grafted polydimethylsiloxane oil D-1, with a viscosity equal to 5500 mPa.Math.s and comprising 2.7% by weight of epoxy groups, are added to 34.4 parts of vinyl terminated polydimethylsiloxane A-1 and 10.26 parts of F-1. The 0.04 parts of inhibitor G-1 are added and then mixed sufficiently. 2.47 parts of a hydrogen-terminated polysiloxane oil B-1 and 1.06 parts of a hydrosiloxane oil B-2 are added and mixed, following with 0.5 parts of E-2 and 0.016 parts of C-1 to obtain curable silicone composition in example 17.

Example 18 is Prepared According to the Following Procedure

[0189] 50 parts of epoxy grafted polydimethylsiloxane oil D-1, with a viscosity equal to 5500 mPa.Math.s and comprising 2.7% by weight of epoxy groups, are added to 21.66 parts of vinyl terminated polydimethylsiloxane A-1, 4.26 parts of F-1 and 20 parts of F-2. 0.04 parts of inhibitor G-1 are added and then mixed sufficiently. 2.47 parts of a hydrogen-terminated polysiloxane oil B-1 and 1.06 parts of a hydrosiloxane oil B-2 are added and mixed, following with 0.5 parts of E-1 and 0.016 parts of C-1 to obtain curable silicone composition in example 18.

Example 19 is Prepared According to the Following Procedure

[0190] 40 parts of epoxy grafted polydimethylsiloxane oil D-1, with a viscosity equal to 5500 mPa.Math.s and comprising 2.7% by weight of epoxy groups, are added to 45.66 parts of vinyl terminated polydimethylsiloxane A-1 and 10.26 parts of F-1. The 0.04 parts of inhibitor G-1 are added and then mixed sufficiently. 2.47 parts of a hydrogen-terminated polysiloxane oil B-1 and 1.06 parts of a hydrosiloxane oil B-2 are added and mixed, following with 0.5 parts of E-1 and 0.016 parts of C-1 to obtain curable silicone composition in example 19.

Examples 20-21 are Prepared According to the Following Procedure

[0191] 50 parts of epoxy grafted polydimethylsiloxane oil D-1, with a viscosity equal to 5500 mPa.Math.s and comprising 2.7% by weight of epoxy groups, are added to 11.72 parts of vinyl terminated polydimethylsiloxane A-1, 17.98 parts of vinyl terminated polydimethylsiloxane A-3 and 11.99 parts of vinyl-containing silioxane resin F-3. The 0.04 parts of inhibitor G-1 are added and then mixed sufficiently. 5.44 parts of a hydrogen-terminated polysiloxane oil B-1 and 2.33 parts of a hydrosiloxane oil B-2 are added and mixed, following with 0.5 parts of E-1 and 0.016 parts of C-1 to obtain curable silicone composition in example 20. Example 21 are similarly prepared according to the above process via adjusting ratio of different raw materials in table 2-b.

Examples 22 (Comparative Example) is Prepared According to the Following Procedure

[0192] 81.88 parts of vinyl terminated polydimethylsiloxane A-1 are mixed with 13.14 parts of F-1. Then 0.04 parts of inhibitor G-1 are added and then mixed sufficiently. 2.45 parts of a hydrogen-terminated polysiloxane oil B-1 and 1.98 parts of a hydrosiloxane oil B-2 are added and mixed, following with 0.5 parts of E-1 and 0.016 parts of C-1 to obtain curable silicone composition.

3D Printing Process by Using the Present Curable Silicone Composition

[0193] The 3D printing process is carried out by using ULTIMAKER 2+ equipment (provided by the company Ultimaker) and a UV light source is added to the equipment. The distance between the UV light source and the printing head is about 30 cm. The composition of example 2 is used as the printing silicone material.

[0194] Printing process is as follows:

[0195] I. Loading the silicone material into an extruder;

[0196] II. Level adjusting the printing platform and setting printing parameters;

[0197] III. Starting printing under the UV light.

[0198] The sample is beamed by a UV Hg lamp, in which the parameters of the UV Hg lamp are as follows.

TABLE-US-00005 Light power: 120 w/cm 20 m/min, UV-A: 147.7 mJ/cm.sup.2 1417.9 mw/cm.sup.2 UV-B: 112.8 mJ/cm.sup.2 1092.8 mw/cm.sup.2 UV-C:  33.4 mJ/cm.sup.2  321.9 mw/cm.sup.2 UV-V: 192.7 mJ/cm.sup.2 1840.7 mw/cm.sup.2

[0199] When the sample according to the invention is beamed for 3 s, the sample loses fluidity and is rapidly formed. In contrast, Examples 3 & 4 which do not contain cationic photoinitiator do not allow to have a “shape figuration” which raise major issues when building complex shapes.

[0200] Every layer according to the invention can be formed and shape figuration can be achieved rapidly under UV light. After finishing the printing, the subsequent curing of the sample is carried out at 80° C. for 30 min to obtain the target 3D printing product.

[0201] As can be seen from the above, in the 3D printing process, the curable silicone composition is initiated by means of UV light to realize a fast-initial curing and then the subsequent curing continues to obtain the desired properties. Thus, the curable silicone composition is well suited for the 3D printing.

Properties Assessments

[0202] The properties assessments on the curable silicone compositions according to the present invention are listed in the tables 2-a and 2-b.

[0203] Viscosity: The viscosity of the sample based on the curable silicone composition is measured at 25° C. according to ASTM D445. The details of measuring conditions are listed in the tables 2-a and 2-b, in which, for example, the expression “(6 #, 20 rpm)” means that the viscosity is measured at 20 rpm by using spindle number 6, and so on.

[0204] Hardness: The hardness of the cured sample based on the curable silicone composition is measured at 25° C. according to ASTM D2240. The details of the measuring conditions are listed in the tables 2-a and 2-b. The cured sample based on the curable silicone composition is obtained under UV irradiation for 30 s, following with subsequent curing at 80° C. for 30 min.

[0205] Tensile strength and Elongation at break: Tensile strength and elongation at break of the cured sample based on the curable silicone composition are measured at 25° C. according to ASTM D412. The details of the measuring conditions are listed in the tables 2-a and 2-b. The cured sample based on the curable silicone composition is obtained under UV irradiation for 30 s, following with subsequent curing at 80° C. for 30 min.

[0206] Tear strength: Tear strength of the cured sample based on the curable silicone composition is measured at 25° C. according to ASTM D642. The details of the measuring conditions are listed in the tables 2-a and 2-b. The cured sample based on the curable silicone composition is obtained under UV irradiation for 30 s, following with subsequent curing at 80° C. for 30 min.

[0207] Bath life: The sample based on the curable silicone composition is stored at 20° C. or 30° C., respectively, until the samples became gelation. The time of gelation is recorded.

[0208] the rate of hardness change: In the present invention, the rate of hardness change is defined as:

[00002]$\mathrm{Rate}\mathrm{of}\mathrm{hardness}\mathrm{change}=\frac{\mathrm{hardness}\mathrm{after}\mathrm{the}\mathrm{completion}\mathrm{of}\mathrm{the}\mathrm{curing}\mathrm{of}\mathrm{the}\mathrm{composition}-\mathrm{hardness}\mathrm{after}\mathrm{UV}\mathrm{initial}\mathrm{curing}\mathrm{of}\mathrm{the}\mathrm{composition}\hspace{1em}}{\mathrm{hardness}\mathrm{after}\mathrm{the}\mathrm{completion}\mathrm{of}\mathrm{the}\mathrm{curing}\mathrm{of}\mathrm{the}\mathrm{composition}\hspace{1em}}\times 100\%$

[0209] in which the expression “hardness after the completion of the curing of the composition” refers to the hardness measured after the composition undergoes epoxy-related UV curing and hydrosilylation curing, and the expression “hardness after UV initial curing of the composition” refers to the hardness measured after the composition initially undergoes epoxy-related UV curing.

[0210] By way of example, the hardness after UV initial curing of the composition may be measured 30 seconds after the start of UV curing, and the hardness after the completion of the curing of the composition may be measured 1 hour after the start of curing the composition.

[0211] As can be seen from the tables 2-a and 2-b, the curable silicone composition according to the present invention allows obtaining fast shape figuration by epoxy-related photocuring and the comprehensive properties by hydrosilylation reaction, including desired mechanical properties such as tensile strength, elongation at break and tear strength. In comparison, the mechanical properties are generally poor if a silicone composition only involves an epoxy-related photocuring, as well known in the art.

[0212] The mechanical properties can be improved via introduction of a filler and/or silicone resin.

[0213] Also, I-3 or I-4, which simultaneously has epoxy group and SiH or vinyl group, can act as a bridge linking between the epoxy-related photocuring system and the hydrosilylation system and thus improve the properties of the composition.

[0214] Epoxy-containing polysiloxane plays an important role in the whole curing. Less Epoxy-containing polysiloxane will cause insufficient shape figuration after UV curing. Meanwhile, the photosensitizer also plays an important role in the final properties of some curable silicone compositions. Suitable content of photosensitizer is helpful for the present curable silicone system.

[0215] In addition, based on ratio of inhibitors and Pt catalyst, the samples with different bath life can be obtained to satisfy different demand of 3D printing.

[0216] In the examples 12-16, different vinyl-containing polysiloxane and epoxy-containing polysiloxane are added into the formulation. The results exhibit the fast shape figuration and the epoxy-related photocuring and the hydrosilylation curing can be obtained, which indicates different raw materials also can achieve the target of the invention. The example 12 and examples 15-16 exhibits good mechanical properties. The examples 13 and 14 give gel sample because of molecular structure and epoxy content of the epoxy-containing polysiloxane.

[0217] In the example 17, cationic photoinitiator E-2 is used, which indicates that different cationic photoinitiators can also offer enough energy to initiate cationic photopolymerization. In the example 18, alumina is added into the present composition involving epoxy-related photocuring and hydrosilylation curing. The results indicate that the addition of alumina has less negative effect on photopolymerization.

[0218] In the example 18-21, hardness of different curing phases are investigated, which shows the present curing system gives epoxy-related photocuring and hydrosilylation curing. The higher the rate of hardness change is, the less contribution of UV initial curing is.

[0219] In the example 22, without epoxy-containing polysiloxane, shape figuration cannot be observed after UV curing.

[0220] The present curable silicone compositions involving epoxy-related photocuring and hydrosilylation curing have been shown in the examples. Proper UV curing mechanism based on epoxy groups has little negative effect on the hydrosilylation reaction, which is very important for the curable system of the invention. The curable silicone compositions have several advantages, such as fast initial curing in combination with the further subsequent curing, such that the comprehensive mechanical properties can be obtained, which are especially suitable for 3D printing.

[0221] FIG. 1 shows the transparency results of the products obtained after curing of the compositions according to the examples 15, 16 and 21 of the invention. The thickness of the cured product is about 2-3mm. The transparencies of these products are evaluated visually. The results are expressed as scores, of which the score 5 represents that the product is completely transparent. The transparency scores of these examples as follows: Example 15 is 3, Example 16 is 2.5 and Example 21 is 4.

[0222] It can be seen that the transparencies of the products obtained from the curable silicone compositions of the invention are adjustable as required.