METHOD FOR MANUFACTURING A SILICONE ELASTOMER ARTICLE USING A 3D PRINTER

Abstract

The present invention relates to a process for manufacturing a silicone elastomer article comprising the following step: 1) providing a composition C, comprising water and at least 20% by weight of at least one poloxamer, into a container; 2) placing the container comprising the composition C at the required temperature T1 to form a gel; 3) printing a crosslinkable silicone composition X into the gel obtained in 2) with a 3D printer at the required temperature T1; 4) optionally allowing the printed composition X to partially or totally crosslink, optionally by heating, to obtain a silicone elastomer article, into the container; 5) optionally placing the container obtained in step 4) at a temperature T3 lower than the sol-gel transition temperature of composition C; 6) recovering the silicone elastomer article; and 7) optionally washing the obtained silicone elastomer article for example with water at a temperature T3 lower than the sol-gel transition temperature of composition C.

Claims

1. Method for manufacturing a silicone elastomer article comprising the following step: 1) providing a composition C, comprising water and at least 20% by weight of at least one poloxamer, into a container; 2) placing the container comprising the composition C at the required temperature T1 to form a gel; 3) printing a crosslinkable silicone composition X into the gel obtained in 2) with a 3D printer at the required temperature Ti; 4) optionally allowing the printed composition X to partially or totally crosslink, optionally by heating, to obtain a silicone elastomer article, in the container; 5) optionally placing the container obtained in step 4) at a temperature T3 lower than the sol-gel transition temperature of composition C; 6) recovering the silicone elastomer article; and 7) optionally washing the obtained silicone elastomer article for example with water at a temperature T3 lower than the sol-gel transition temperature of composition C.

2. Method according to claim 1 comprising the following step: 1) providing a composition C, comprising water and at least 20% by weight of at least one poloxamer, into a container; 2) placing the container comprising the composition C at the required temperature T1 to form a gel; 3) printing a crosslinkable silicone composition X into the gel obtained in 2) with a 3D printer at the required temperature Ti; 4) allowing the printed composition X to partially or totally crosslink, optionally by heating, to obtain a silicone elastomer article, in the container; 5) optionally placing the container obtained in step 4) at a temperature T3 lower than the sol-gel transition temperature of composition C; 6) recovering the silicone elastomer article; and 7) optionally washing the obtained silicone elastomer article for example with water at a temperature T3 lower than the sol-gel transition temperature of composition C.

3. Method according to claim 1 wherein the poloxamer is a copolymer composed of poly(propylene oxide) and polyethylene oxide) blocks.

4. Method according to claim 1 wherein the poloxamer is a triblock copolymer composed of a central poly(propylene oxide) block and two terminal poly(ethylene oxide) blocks.

5. Method according to claim 1, wherein the poloxamer comprises from 25 to 90% by weight of poly(ethylene oxide) units based on the total weight of the poloxamer.

6. Method according to claim 1, wherein the poloxamer is a triblock copolymer composed of a central poly(propylene oxide) block and two terminal poly(ethylene oxide) block for which the two poly(ethylene oxide) block comprise each 100+/−10 repeat units and the poly(propylene oxide) block comprises 55+/−10 repeat units.

7. Method according to claim 1 wherein composition C comprises from 20 to 40% by w eight of at least one poloxamer.

8. Method according to claim 1, wherein the composition C further comprises one or more compounds chosen from the group consisting of: a base, for example NaOH; an acid, for example acetic acid; and a functionalized silane, for example with amino, epoxy, hydroxy, polyether groups.

9. Method according to claim 1 wherein: T1 is comprised between 25 and 50° C., preferably between 25 and 40° C., for example between 25 and 35° C., more preferably between 28 and 32° C., and/or T3 is lower than 15° C., preferably comprised between 0 and 15° C., preferably between 0 and 10° C.

10. Method according to claim 1, wherein steps 5 and 6 are reversed.

11. Method according to claim 1, wherein after step 5 composition C is recovered and is recycled in step 1.

12. Method according to claim 1, wherein composition C comprises from 21.5 to 22.5% by weight of poloxamer based on the total weight of composition C.

13. Method according to claim 1, wherein the crosslinkable composition X has a viscosity comprised between 1000 mPa.Math.s and 1000000 mPa.Math.s.

14. Method according to claim 1, wherein the crosslinking step 4 is made by heating at a temperature between 30 and 90° C., preferably between 40 and 70° C.

15. Method for manufacturing a silicone elastomer article with a 3D printer comprising the use of a composition C as defined in claim 1 as a constrained environment.

Description

EXAMPLES

Steps 1 and 2: Preparation of Compositions C

[0289] Composition C1: 21.75 weight % of Pluronic F127® (BASF) was dissolved in water. The composition is placed in a container which is placed at 30° C. (T1) to form a gel.

[0290] Composition C2: 21.75 weight % of Pluronic F127® (BASF) was dissolved in 10M NaOH aqueous solution (pH>8). The composition is placed in a container which is placed at 30° C. (T1) to form a gel.

Preparation of Crosslinkable Silicone Compositions X

[0291] Preparation of Composition X1 (Viscosity 2000 mPa.Math.s at 25° C./Shear 0.5 s.sup.−1):

[0292] Composition X1 is a bicomponent composition which comprises a first part A and a second part B, as follow:

[0293] Part A [0294] 28.57 parts dimethylpolysiloxane oil blocked at both ends by Me.sub.2ViSiO.sub.1/2 units, having a viscosity of 600 mPa.Math.s [0295] 5 parts of a dimethylpolysiloxane blocked at both ends by Me.sub.2ViSiO.sub.1/2 units, having a viscosity of 100000 mPa.Math.s [0296] 6.42 parts of silica fumed treated hexamethyldisilazane with a specific surface area measured by the BET method of 200 m.sup.2/g [0297] 10 parts of dimethylsiloxane oil blocked at both ends by Me.sub.3SiO.sub.1/2 units, having a viscosity of 50 mPa.Math.s [0298] Platinum metal introduced in the form of an Organometallic complex at 10% by weight of Platinum metal, known as Karstedt's catalyst diluted in a vinyl oil such as the Pt content of the composition is 10 ppm in part A

[0299] Part B: [0300] 17.57 parts dimethylpolysiloxane oil blocked at both ends by Me.sub.2ViSiO.sub.1/2 units, having a viscosity of 600 mPa.Math.s [0301] 5 parts of a dimethylpolysiloxane blocked at both ends by Me.sub.2ViSiO.sub.1/2 units, having a viscosity of 100000 mPa.Math.s [0302] 6.42 parts of silica fumed treated hexamethyldisilazane with a specific surface area measured by the BET method of 200 m.sup.2/g [0303] 10 parts of dimethylsiloxane oil blocked at both ends by Me.sub.3SiO.sub.1/2 units, having a viscosity of 50 mPa.Math.s [0304] 11 parts of an organohydrogenopolysiloxane comprising Si—H groups in the chain and at chain ends and containing approximately 18.75% molar groups Si—H [0305] 0.005 parts of tetramethyltetravinylcyclotetrasiloxane
Preparation of Composition X2 (Viscosity >150000 mPa.Math.s; 25° C. Shear 0.551:

[0306] Composition X2 is a monocomponent composition with is prepared as follows.

[0307] A first base is prepared by mixing: [0308] 29 parts dimethylpolysiloxane oil blocked at both ends by Me.sub.2ViSiO.sub.1/2 units, having a viscosity of 60000 mPa.Math.s [0309] 29 parts of a dimethylpolysiloxane blocked at both ends by Me.sub.2ViSiO.sub.1/2 units, having a viscosity of 100000 mPa.Math.s [0310] 26 parts of silica fumed with a specific surface area measured by the BET method of 300 m2/g and [0311] 7 parts of hexamethyldisilazane.

[0312] This first base is heated at 70° C. under agitation for 1 hour and then devolatilised, cooled and stored as a base.

[0313] Then a part A composition is prepared by adding to 45 parts of this base in a speed mixer: [0314] Platinum metal which is introduced in the form of an Organometallic complex at 10% by weight of Platinum metal, known as Karstedt's catalyst diluted in a vinyl oil. [0315] 3 parts: dimethylpolysiloxane oil having vinyl groups in the chain and at the chain ends and having a viscosity of 1000 mPa.Math.s [0316] 2 parts of a dimethylpolysiloxane oil having vinyl groups in the chain and at the chain ends and having a viscosity of 400 mPa.Math.s

[0317] The resulting part A composition is mixed during one minute at 1000 rounds/minute in the speed mixer. The Pt content of this part A composition is 5 ppm

[0318] Then a part B is prepared by adding to 45 parts of the base is then added in a speed mixer: [0319] 1.3 parts of an organohydrogenopolysiloxane M′Q resin comprising Si—H groups [0320] 0.5 parts of an organohydrogenopolysiloxane comprising Si—H groups in the chain and at chain ends and containing approximately 20% by weight of groups Si—H [0321] 1.5 parts of a dimethylpolysiloxane oil having vinyl groups in the chain and at the chain ends and having a viscosity of 400 mPa.Math.s [0322] 1.6 parts: dimethylpolysiloxane oil having vinyl groups in the chain and at the chain ends and having a viscosity of 1000 mPa.Math.s and [0323] 0.08 parts of ethynyl-1-cyclohexanol-1 as crosslinking inhibitor

[0324] The resulting part B is mixed during one minute at 1000 rounds/minute in the speed mixer.

[0325] Composition X2 is then obtained by mixing 50 parts of part A and 50 parts of part B during one minute at 1000 rounds/minute in the speed mixer. The bath life of this composition X2 at 25° C. is greater than 24 hours and lower than 48 hours.

Preparation of Composition X3 (Viscosity >150000 mPa.Math.s; 25° C. Shear 0.551:

[0326] Composition X3 is a monocomponent composition and is prepared by mixing at ambient temperature: [0327] 76.5 parts dimethylpolysiloxane oil blocked at both ends by Me.sub.2(OH)SiO.sub.1/2 units, having a viscosity of 80000 mPa.Math.s [0328] 9.2 parts of a MDT resin with a molar ratio Me.sub.3SiO.sub.1/2 4%; Me.sub.2SiO.sub.2/2 70%; MeSiO.sub.3/2 26% [0329] 10.7 parts of silica fumed with a specific surface area measured by the BET method of 55 m2/g [0330] 2.9 Parts of methyltriacetoxysilane as crosslinker [0331] 0.7 parts of ethyltriacetoxysilane as crosslinker [0332] 0.0036 parts of titanatetetrabutoxyde as catalyst.

Example 1: Steps 3, 4, 6 and 7 Carried Out with Composition C1 and Composition X1

Step 3:

[0333] Part A and part B of composition X1 with viscosity 2000 mPa.Math.s are extruded through the double cartridge Equalizer™ from Nordson EFD (bicomponent system bath life after mixing Part A and Part B 20 min at 20° C.) through a static mixer and a nozzle with a strand diameter of 400 μm, at a rate between 0.1 to 5 ml/s in in composition C1 at 30° C. micro-gel to produce layer by layer a 3D article.

Step 4:

[0334] After printing, the silicone composition X1 is crosslinked by placing the container at 60° C. during 2 h.

Step 6:

[0335] The silicone elastomer article is then removed from the composition C1.

Step 7:

[0336] The recovered silicone elastomer article is washed with cold water at 10° C. for 5 minutes.

[0337] The mechanical properties of the 3D printed silicone elastomer article are in good fit with the mechanical properties claimed for a molded silicone article obtained from composition X1.

[0338] Dumbbell samples are prepared.

[0339] The shore A hardness according ASTM-D2240/C is 3. Such article can be used for dental applications.

Example 2: Steps 3 to 7 Carried Out with Composition C1 and Composition X2

Step 3:

[0340] Composition X2 with viscosity >150000 mPa.Math.s is extruded through the single cartridge Ultimus V Nordson EFD equipment (monocomponent system) at a flow rate between 0.01 and 1 ml/s through a nozzle with a strand diameter of 400 μm in composition C1 at 30° C. to produce layer by layer a 3D article.

Step 4:

[0341] After printing, the silicone composition X2 is crosslinked by placing the container at 70° C. during 1 h.

Step 5:

[0342] The composition C1 which forms a gel at 30° C., is placed at 10° C. in order to liquefy the gel. The liquefied gel obtained is used for another printing process according to the invention without loss of properties.

Step 6:

[0343] The silicone elastomer article is then removed from the composition C1.

Step 7:

[0344] The recovered silicone elastomer article is washed with cold water at 10° C. for 5 minutes.

Additional Crosslinking Step

[0345] Then the object is further crosslinked at 120° C. during 2 h.

[0346] The mechanical properties of the printed objects are in good fit with the mechanical properties claimed for a molded object obtained from composition X2.

[0347] Dumbbell samples are prepared (a sample obtained by the printing process according to the invention and a molded object with same composition X2 obtained by molding) and the results obtained regarding mechanical properties on a 2 mm thick film (NF T 46002) are the following:

Hardness ASTM D2240: printed sample 50/Injection Molded sample 50
Tensile Strength ASTM-D412: Printed sample 7.6 MPa/Injection-Molded sample 8.4 MPa
Elongation ASTM-D412: Printed sample 490%/Injection molded sample 530%
Modulus 100% ASTM-D412: Printed sample 2.3 MPa/Injection Molded sample 2.3 MPa

Example 3—Steps 3, 6 and 7 Carried Out with Composition C1 and Composition X3

Step 3:

[0348] Composition X3 with viscosity >150000 mPa.Math.s is extruded (Ultimus Nordson) at a flow rate between 0.1 to 5 ml/s through a nozzle with a strand diameter of 400 μm in composition C1 at 30° C. to produce layer by layer a 3D article.

Step 6:

[0349] After printing the silicone elastomer article is removed from the composition C1.

Step 7:

[0350] The recovered silicone elastomer article is washed with cold water at 10° C. for 5 minutes.

[0351] The mechanical properties (after 48 hours at room temperature) of the printed objects are in good fit with the mechanical properties claimed for a molded object obtained from composition X3.

[0352] Dumbbell sample are prepared according to the invention and also molded object obtained from composition X3. Mechanical properties on a 2 mm thick film (NF T 46002) (dumbbell sample) at a temperature of 23° C. and relative humidity of 50%, are the followings:

Tensile Strength ASTM-D412: Printed sample 1.8 MPa/Molded sample 1.9 MPa
Elongation at break ASTM-D412: Printed sample 600%/Molded sample 500%
Modulus 100% ASTM-D412: Printed sample 0.45 MPa/Molded sample 0.5 MPa
Shore A Hardness (ISO 868): Printed sample at 20/Molded sample at 23

Example 4—Steps 3, 4, 6 and 7 Carried Out with Composition C2 and Composition X2

Step 3:

[0353] Composition X2 with viscosity >150000 mPa.Math.s is extruded through the single cartridge Ultimus V Nordson EFD equipment (monocomponent system) at a flow rate between 0.01 and 1 ml/s through a nozzle with a strand diameter of 400 μm in composition C2 at 30° C. to produce layer by layer a 3D article.

Step 4:

[0354] The printed composition X2 obtained in step 3) is let during 10-24 hours in composition C2 at 30° C.

Step 6

[0355] After printing the silicone elastomer article is removed from the composition C2.

Step 7:

[0356] The recovered silicone elastomer article is washed with cold water at 10° C. for 5 minutes.

Example 5—Steps 3, 6 and 7 Carried Out with Composition C2 and Composition X2

Step 3:

[0357] Composition X2 with viscosity >150000 mPa.Math.s is extruded through the single cartridge Ultimus V Nordson EFD equipment (monocomponent system) at a flow rate between 0.01 and 1 ml/s through a nozzle with a strand diameter of 400 μm in composition C2 at 30° C. to produce layer by layer a 3D article.

Step 6

[0358] After printing the silicone elastomer article is removed from the composition C2.

Step 7:

[0359] The recovered silicone elastomer article is washed with cold water at 10° C. for 5 minutes.