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. A method for manufacturing a silicone elastomer article comprising: 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 a 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) allowing the printed composition X to partially or totally crosslink, by heating at a temperature between 30 C. and 90 C. to obtain a silicone elastomer article, in the container; 5) placing the container obtained in 4) at a temperature T3 lower than the sol-gel transition temperature of composition C; 6) after 5), recovering the silicone elastomer article; and 7) optionally washing the obtained silicone elastomer article for example with water at the temperature T3 lower than the sol-gel transition temperature of composition C; wherein after 5), composition C is recovered in a reusable form and is recycled in 1).

2. The method according to claim 1 wherein the poloxamer is a copolymer composed of poly(propylene oxide) and poly(ethylene oxide) blocks.

3. The 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.

4. The 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.

5. The 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.

6. The method according to claim 1 wherein composition C comprises from 20 to 40% by weight of at least one poloxamer.

7. The method according to claim 1, wherein the composition C further comprises one or more compounds chosen from the group consisting of: a base; an acid; and a functionalized silane.

8. The method according to claim 7, wherein the base is NaOH, and wherein the acid is acetic acid.

9. The method according to claim 7, wherein the functionalized silane is functionalized with a moiety selected from the group consisting of amino, epoxy, hydroxy, and polyether groups.

10. The method according to claim 1 wherein: T1 is comprised between 25 and 50 C., and/or T3 is lower than 15 C.

11. The method according to claim 10 wherein: T1 is comprised between 25 and 35 C., and/or T3 is comprised between 0 and 10 C.

12. The method according to claim 10 wherein: T1 is comprised between 25 and 40 C., and/or T3 is comprised between 0 and 15 C.

13. The method according to claim 1, wherein 5) and 6) are reversed.

14. The 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.

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

16. The method for manufacturing a silicone elastomer article according to claim 1, wherein the silicone elastomer article is manufactured using a 3D printer.

17. The method according to claim 1, wherein the crosslinking is made by heating at a temperature between 40 and 70 C.

Description

EXAMPLES

Steps 1 and 2: Preparation of Compositions C

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

(2) Composition X1 is a bicomponent composition which comprises a first part A and a second part B, as follow:

(3) Part A

(4) 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 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 6.42 parts of silica fumed treated hexamethyldisilazane with a specific surface area measured by the BET method of 200 m.sup.2/g 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 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
Part B: 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 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 6.42 parts of silica fumed treated hexamethyldisilazane with a specific surface area measured by the BET method of 200 m.sup.2/g 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 11 parts of an organohydrogenopolysiloxane comprising SiH groups in the chain and at chain ends and containing approximately 18.75% molar groups SiH 0.005 parts of tetramethyltetravinylcyclotetrasiloxane
Preparation of Composition X2 (Viscosity >150000 mPa.Math.s; 25 C. Shear 0.551:

(5) Composition X2 is a monocomponent composition with is prepared as follows.

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

(7) This first base is heated at 70 C. under agitation for 1 hour and then devolatilised, cooled and stored as a base.

(8) Then a part A composition is prepared by adding to 45 parts of this base in a speed mixer: 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. 3 parts: dimethylpolysiloxane oil having vinyl groups in the chain and at the chain ends and having a viscosity of 1000 mPa.Math.s 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

(9) 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

(10) Then a part B is prepared by adding to 45 parts of the base is then added in a speed mixer: 1.3 parts of an organohydrogenopolysiloxane MQ resin comprising SiH groups 0.5 parts of an organohydrogenopolysiloxane comprising SiH groups in the chain and at chain ends and containing approximately 20% by weight of groups SiH 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 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 0.08 parts of ethynyl-1-cyclohexanol-1 as crosslinking inhibitor

(11) The resulting part B is mixed during one minute at 1000 rounds/minute in the speed mixer.

(12) 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.

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

(14) Composition X3 is a monocomponent composition and is prepared by mixing at ambient temperature: 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 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% 10.7 parts of silica fumed with a specific surface area measured by the BET method of 55 m2/g 2.9 Parts of methyltriacetoxysilane as crosslinker 0.7 parts of ethyltriacetoxysilane as crosslinker 0.0036 parts of titanatetetrabutoxyde as catalyst.

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

(15) Step 3:

(16) 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 m, 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.

(17) Step 4:

(18) After printing, the silicone composition X1 is crosslinked by placing the container at 60 C. during 2 h.

(19) Step 6:

(20) The silicone elastomer article is then removed from the composition C1.

(21) Step 7:

(22) The recovered silicone elastomer article is washed with cold water at 10 C. for 5 minutes.

(23) 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.

(24) Dumbbell samples are prepared.

(25) 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

(26) Step 3:

(27) 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 m in composition C1 at 30 C. to produce layer by layer a 3D article.

(28) Step 4:

(29) After printing, the silicone composition X2 is crosslinked by placing the container at 70 C. during 1 h.

(30) Step 5:

(31) 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.

(32) Step 6:

(33) The silicone elastomer article is then removed from the composition C1.

(34) Step 7:

(35) The recovered silicone elastomer article is washed with cold water at 10 C. for 5 minutes.

(36) Additional Crosslinking Step

(37) Then the object is further crosslinked at 120 C. during 2 h.

(38) The mechanical properties of the printed objects are in good fit with the mechanical properties claimed for a molded object obtained from composition X2.

(39) 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 3Steps 3, 6 and 7 Carried Out with Composition C1 and Composition X3

(40) Step 3:

(41) 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 m in composition C1 at 30 C. to produce layer by layer a 3D article.

(42) Step 6:

(43) After printing the silicone elastomer article is removed from the composition C1.

(44) Step 7:

(45) The recovered silicone elastomer article is washed with cold water at 10 C. for 5 minutes.

(46) 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.

(47) 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 4Steps 3, 4, 6 and 7 Carried Out with Composition C2 and Composition X2

(48) Step 3:

(49) 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 m in composition C2 at 30 C. to produce layer by layer a 3D article.

(50) Step 4:

(51) The printed composition X2 obtained in step 3) is let during 10-24 hours in composition C2 at 30 C.

(52) Step 6

(53) After printing the silicone elastomer article is removed from the composition C2.

(54) Step 7:

(55) The recovered silicone elastomer article is washed with cold water at 10 C. for 5 minutes.

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

(56) Step 3:

(57) 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 m in composition C2 at 30 C. to produce layer by layer a 3D article.

(58) Step 6

(59) After printing the silicone elastomer article is removed from the composition C2.

(60) Step 7:

(61) The recovered silicone elastomer article is washed with cold water at 10 C. for 5 minutes.