METHOD FOR MANUFACTURING A MULTI-CAPILLARY LINING

Abstract

The present disclosure relates to a method for manufacturing multi-capillary lining that can serve as a chromatographic column, and to the multi-capillary packing obtained by such a method.

Claims

1. Method for manufacturing a multi-capillary packing from a substrate of ablative preforms, each preform being suitable for forming, during its ablation, a conduit enabling the convection of a fluid in said packing, said method comprising the following steps: (a) assembling the ablative preforms in the form of at least one bundle; (b) creating a gel between the ablative preforms of the bundle by hydrolysis of an organometallic precursor in the presence of a quantity of water not exceeding ten times the stoichiometric quantity required for complete hydrolysis of said organometallic precursor; (c) ablating the preforms, preferably by pyrolysis, oxidation, vaporisation, melting and drainage, mechanical extraction or chemical attack, so as to form a plurality of conduits in the gel.

2. Method according to claim 1, further comprising a drying step between steps (b) and (c) or after step (c).

3. Method according to claim 2, wherein the drying is carried out under vacuum at ambient temperature.

4. Method according to one of the preceding claims, wherein the organometallic precursor is an organometallic alkaloid, organometallic acetate, organometallic carboxylate, organometallic halide, organometallic nitrate, organometallic alkanoate, organometallic acyloxide, or one of the mixtures thereof.

5. Method according to one of the preceding claims, wherein the organometallic precursor is chosen from the organometallic derivatives of silicon, aluminium, zirconium, titanium, a rare earth such as yttrium, cerium or lanthanum, boron, iron, magnesium, calcium, strontium, barium, germanium, phosphorus, lithium, potassium, sodium, niobium, copper, or one of the mixtures thereof.

6. Method according to one of the preceding claims, wherein the organometallic precursor is tetramethoxysilane or tetraethoxysilane.

7. Method according to one of the preceding claims, wherein the gel has a pore volume of between 20% and 90% by volume of the gel, advantageously between 40% and 65% by volume of the gel.

8. Method according to one of the preceding claims, wherein the preforms comprise yarns of polyamide, polyolefin, polyacrylate, polymethacrylate, polysulfone, polyurethane, polyimide, polyether or polyester yarns.

9. Method according to claim 8, wherein the polyester yarns are hydrolysable polyester yarns.

10. Method according to one of the preceding claims, wherein the ablative preforms are covered with a porous granular substance before assembling in bundle form.

11. Method according to one of the preceding claims, wherein the ablative preforms are shaped into segments occluded in the body of the packing.

12. Method according to one of the preceding claims, wherein the gel is a silica gel.

13. Method according to claim 12, wherein the gel is a multimodal silica gel and wherein the quantity of water does not exceed six times the stoichiometric quantity required for complete hydrolysis of said organometallic precursor, preferably wherein the quantity of water does not exceed five times the stoichiometric quantity required for a complete hydrolysis of said organometallic precursor, still more preferably wherein the quantity of water does not exceed four times the stoichiometric quantity required for complete hydrolysis of said organometallic precursor.

14. Multi-capillary packing that can be obtained by the method of one of the preceding claims.

Description

[0131] The present invention also relates to a packing that can be obtained by the method of the present invention.

[0132] FIG. 1 shows schematically, viewed in axial section, a multi-capillary packing according to the invention comprising continuous conduits 2 extending axially between an inlet face 3 and an outlet face 4 in a porous mass 1 obtained by a sol gel method.

[0133] FIG. 2 shows schematically, viewed in axial section, a multi-capillary packing according to the invention comprising discontinuous conduits arranged in the form of segments 5 extending axially between an inlet face 3 and an outlet face 4 and occluded in a porous mass 1 obtained by a sol gel method.

[0134] Embodiments of the invention are illustrated in the following examples. These examples in no way limit the present invention.

EXAMPLES

Example 1

[0135] In this example, the precursor polymer fibres of the conduits are assembled into a bundle, the bundle is immersed in a precursor solution of a silica gel, which solution causes the gel around the fibre, then the fibres are eliminated by pyrolysis and combustion.

[0136] A monofilament of polyamide (of external diameter approximately 100 μm) is soaked in an aqueous solution containing 10% polyvinyl alcohol and 15% by weight glass microbeads supplied by Potters Ballotini having a particle size distribution with diameters between 40 and 70 μm. The monofilament is then dried. In this way, the outside of the polyamide filament is covered with silica gel microbeads which act as spacers, adhering to its surface through the action of the PVA which acts as glue.

[0137] The bundle is manufactured by assembling these filaments into a bundle of rectangular cross-section, of width 1700 μm, depth 250 μm and length 100 mm. This bundle is created by winding in a conduit precisely machined in a sheet of stainless steel 316 L, of dimensions 100 mm×20 mm×10 mm. The bundle of polyamide fibres is impregnated by a mixture of 25 ml tetraethoxysilane, 10.0 ml mineralised water and 0.35 ml 1N ammonia solution stirred beforehand until a single phase mixture is formed. The liquid must completely wet and fill the conduit as well as the packing. The packing is closed by a top cover consisting of a flat sheet of stainless steel of dimensions identical to those of the base steel sheet, screwed onto the latter, on which is previously deposited a thickness of approximately 5 micrometres of a paraffin melting at 90° C.

[0138] The mixture is left to polymerise and gel for 24 hours at 80° C.

[0139] The two ends of the packing thus formed are cut flush with the steel sheet so as to release the section of the packing.

[0140] The packing has a length of 100 mm.

[0141] The cover is removed after having brought the packing to a temperature of 95° C. so as to melt the paraffin, and the packing is vacuum dried at 2 kPa and at a temperature of 20° C. for 48 hours.

[0142] The resulting product is heated to 550° C. in an air atmosphere in order to convert it into a multi-capillary packing by burning off the polymer fibres.

[0143] Once cooled, the packing is re-closed on its upper part by a flat stainless steel sheet of the same dimensions, or cover, screwed on that containing the packing.

Example 2

[0144] In this example, the precursor polymer fibres of the conduits are assembled into a bundle, the bundle is immersed in a precursor solution of a silica gel, which solution causes the gel around the fibre, then the fibres are eliminated by pyrolysis and combustion.

[0145] A monofilament of polyamide (of external diameter approximately 100 μm) is soaked in an aqueous solution containing 10% polyvinyl alcohol and 15% by weight glass microbeads supplied by Potters Ballotini having a particle size distribution with diameters between 40 and 70 μm. The monofilament is then dried. In this way, the outside of the polyamide filament is covered with glass microbeads which act as spacers, adhering to its surface through the action of the PVA which acts as glue.

[0146] The bundle is manufactured by assembling these filaments into a bundle of rectangular cross-section, of width 1700 μm, depth 250 μm and length 100 mm. This bundle is created by winding in a conduit precisely machined in a sheet of stainless steel 316 L, of dimensions 100 mm×20 mm×10 mm. The bundle of polyamide fibres is impregnated by a mixture of 25 ml tetraethoxysilane, 10.0 ml mineralised water and 0.35 ml 1N ammonia solution stirred beforehand until a single-phase mixture is formed, and 5 grams of mesoporous silica nanoparticles of particle diameter 20 nm and specific surface area 600 m.sup.2/g, reference 637246 from Sigma Aldrich. The liquid must completely wet and fill the conduit as well as the packing.

[0147] The packing is closed by a top cover consisting of a flat sheet of stainless steel of dimensions identical to those of the base steel sheet, screwed onto the latter, on which is previously deposited a thickness of approximately 5 micrometres of a paraffin melting at 90° C.

[0148] The mixture is left to polymerise and gel for 24 hours at 80° C.

[0149] The two ends of the packing are cut flush with the steel sheet so as to release the section of the packing.

[0150] The packing has a length of 100 mm.

[0151] The cover is removed after having brought the packing to a temperature of 95° C. so as to melt the paraffin, and the packing is vacuum dried at 2 kPa and at a temperature of 20° C. for 48 hours.

[0152] The resulting product is heated to 550° C. in an air atmosphere in order to convert it into a multi-capillary packing by burning off the polymer fibres.

[0153] Once cooled, the packing is re-closed on its upper part by a flat stainless-steel sheet of the same dimensions, or cover, screwed on that containing the packing.

Example 3

[0154] In this example, precursor polymer fibres of the conduits are assembled into a bundle, the bundle is immersed in a precursor solution of a silica gel, which solution causes the gel around the fibre, then the fibres are eliminated by pyrolysis and combustion.

[0155] A monofilament of polyamide (of external diameter approximately 100 μm) is soaked in an aqueous solution containing 10% polyvinyl alcohol and 15% by weight glass microbeads supplied by Potters Ballotini having a particle size distribution with diameters between 40 and 70 μm. The monofilament is then dried. In this way, the outside of the polyamide filament is covered with glass microbeads which act as spacers, adhering to its surface through the action of the PVA which acts as glue.

[0156] The bundle is manufactured by assembling these filaments into a bundle of rectangular cross-section, of width 1700 μm, depth 250 μm and length 100 mm. This bundle is created by winding in a conduit precisely machined in a sheet of stainless steel 316 L, of dimensions 100 mm×20 mm×10 mm. The bundle of polyamide fibres is impregnated by a mixture of 25 ml tetraethoxysilane, 10.0 ml mineralised water and 0.35 ml 1N ammonia solution stirred beforehand until a single-phase mixture is formed, and 1 g of potassium titanate fibres of diameter 0.2 μm, length 18 μm, marketed under the trade name TISMO D by Otsuka Chemical Co, Ltd. The liquid must completely wet and fill the conduit as well as the packing. The packing is closed by a top cover consisting of a flat sheet of stainless steel of dimensions identical to those of the base steel sheet, screwed onto the latter, on which is previously deposited a thickness of approximately 5 micrometres of a paraffin melting at 90° C.

[0157] The mixture is left to polymerise and gel for 24 hours at 80° C.

[0158] The two ends of the packing thus formed are cut flush with the steel sheet so as to release the section of the packing.

[0159] The packing has a length of 100 mm.

[0160] The cover is removed after having brought the packing to a temperature of 95° C. so as to melt the paraffin, and the packing is vacuum dried at 2 kPa and at a temperature of 20° C. for 48 hours.

[0161] The resulting product is heated to 550° C. in an air atmosphere in order to convert it into a multi-capillary packing by burning off the polymer fibres.

[0162] Once cooled, the packing is re-closed on its upper part by a flat stainless-steel sheet of the same dimensions, or cover, screwed on that containing the packing.

Example 4

[0163] In this example, precursor polymer fibres of the conduits are assembled into a bundle, the bundle is immersed in a precursor solution of a silica gel, which solution causes the gel around the fibre, then the fibres are eliminated by pyrolysis and combustion.

[0164] A monofilament of polyamide (of external diameter approximately 100 μm) is soaked in an aqueous solution containing 10% polyvinyl alcohol and 15% by weight glass microbeads supplied by Potters Ballotini having a particle size distribution with diameters between 40 and 70 μm. The monofilament is then dried. In this way, the outside of the polyamide filament is covered with glass microbeads which act as spacers, adhering to its surface through the action of the PVA which acts as glue.

[0165] The bundle is manufactured by assembling these filaments into a bundle of rectangular cross-section, of width 1700 μm, depth 250 μm and length 100 mm. This bundle is created by winding in a conduit precisely machined in a sheet of stainless steel 316 L, of dimensions 100 mm×20 mm×10 mm. The bundle of polyamide fibres is impregnated by a mixture of 25 ml tetramethoxysilane and 20.0 ml mineralised water, stirred beforehand until a single-phase mixture is formed. The liquid must completely wet and fill the conduit as well as the packing.

[0166] The packing is closed by a top cover consisting of a flat sheet of stainless steel of dimensions identical to those of the base steel sheet, screwed onto the latter, on which is previously deposited a thickness of approximately 5 micrometres of a paraffin melting at 90° C.

[0167] The mixture is left to polymerise and gel for 24 hours at 80° C.

[0168] The two ends of the packing thus formed are cut flush with the steel sheet so as to release the section of the packing.

[0169] The packing has a length of 100 mm.

[0170] The cover is removed after having brought the packing to a temperature of 95° C. so as to melt the paraffin, and the packing is vacuum dried at 2 kPa and at a temperature of 20° C. for 48 hours.

[0171] The resulting product is heated to 550° C. in an air atmosphere in order to convert it into a multi-capillary packing by burning off the polymer fibres.

[0172] Once cooled, the packing is re-closed on its upper part by a flat stainless-steel sheet of the same dimensions, or cover, screwed on that containing the packing.

Example 5

[0173] In this example, precursor polymer fibres of the conduits are assembled into a bundle, the bundle is immersed in a precursor solution of a silica gel, which solution causes the gel around the fibre, then the fibres are eliminated by pyrolysis and combustion.

[0174] A monofilament of polyamide (of external diameter approximately 100 μm) is soaked in an aqueous solution containing 10% polyvinyl alcohol and 15% by weight glass microbeads supplied by Potters Ballotini having a particle size distribution with diameters between 40 and 70 μm. The monofilament is then dried. In this way, the outside of the polyamide filament is covered with glass microbeads which act as spacers, adhering to its surface through the action of the PVA which acts as glue.

[0175] The bundle is manufactured by assembling these filaments into a bundle of rectangular cross-section, of width 1700 μm, depth 250 μm and length 100 mm. This bundle is created by winding in such a conduit precisely machined in a sheet of titanium (ASTM grade 2) that is 100 mm×20 mm×10 mm.

[0176] The bundle of polyamide fibres is impregnated with a mixture of 1.6 g of Brij 56 (commercial surfactant), 1 g dodecane, 4 g tetramethoxysilane, and 2 g of 0.05N HCl in deionised water. TEOS, dodecane and Brij are mixed at 50° C. until the mixture is homogeneous. The 0.5N acid (HCl) is then added under vigorous stirring. The mixture is poured into the conduit bearing the fibres.

[0177] The packing is closed by a top cover consisting of a flat sheet of titanium (ASTM grade 2) of dimensions identical to those of the base titanium sheet, screwed onto the latter, on which is previously deposited a thickness of approximately 5 micrometres of a paraffin melting at 90° C.

[0178] The mixture is left to polymerise and gel for 24 hours at 20° C.

[0179] The two ends of the packing are cut flush with the titanium sheet so as to release the section of the packing.

[0180] The packing has a length of 100 mm.

[0181] The cover is removed, and the packing is vacuum dried at 2 kPa and at a temperature of 20° C. for 48 hours.

[0182] The resulting product is heated to 550° C. in an air atmosphere in order to convert it into a multi-capillary packing by burning off the polymer fibres.

[0183] Once cooled, the packing is re-closed on its upper part by a flat sheet of titanium (ASTM grade 2) of the same dimensions, or cover, screwed on that containing the packing.

[0184] Once cooled, the packing is re-closed on its upper part by a flat stainless-steel sheet of the same dimensions, or cover, screwed on that containing the packing.

Example 6

[0185] A preform of the conduits of the monolith is produced by producing a bundle composed of segments of carbon fibres of diameter 4.8 μm and length five millimetres.

[0186] The bundle of these segments or needles is then inserted at the bottom of a recess of width 2.0 mm, depth 2 mm and length 75 mm hollowed out in a 20×10×75 mm sheet of stainless steel 316 L so as to produce a stack of naturally packed needles aligned along the length of the conduit. A flat cover is prepared in a 20×10×75 mm sheet of PTFE.

[0187] The bundle is produced with a length of 75 mm.

[0188] A silicic monolith is synthesised from tetraethoxysilane (TEOS, Aldrich 99%), polyethylene oxide (PEO, molar mass=10,000, Aldrich 99%), nitric acid (68%, Aldrich) and NH4OH (analytical purity, Aldrich).

[0189] A 250 mL Erlenmeyer flask is placed in an ice bath at 0° C. with a magnetic bar. Then, demineralised water (36 g, 2 mol) and nitric acid (68% HNO3, 3.60 g, 38.84 mmol) are added and stirred at 500 rpm for 15 min. Then, PEO (4.79 g PEO including 0.11 mol unit EO) is added and the mixture is stirred for one hour at 700 rpm in order that all the PEO is dissolved. TEOS (37.70 g, 0.18 mol) is then added and the mixture is stirred for one hour. The transparent solution obtained is then poured using a 10 mL pipette in the core of the previously obtained bundle of segments, stored beforehand in a dry environment at 0° C. before filling. The bar is then placed in an oven under a saturated atmosphere of water vapour at 40° C. for 72 hours. The PTFE cover is removed.

[0190] The bar is immersed in a 2 L beaker with 1500 mL of demineralised water at ambient temperature for 1 h. The monolith is then washed four times in the same way, by immersion in the demineralised water (500 mL, 1 h) until a neutral pH is obtained. The monolith is then subjected to a base treatment. It is then immersed in 400 mL of an ammonia solution (0.1 M) in a polypropylene flask (500 mL). The flask is then placed in an oven at 40° C. for 24 hours.

[0191] The recovered monolith is rinsed using a wash bottle with distilled water, dried at ambient temperature for 48 h and at 40° C. for 24 h on a flat surface.

[0192] It is calcined at 650° C. under air for 24 hours (ramp 1° C. min-1).

[0193] A flat cover is prepared in a 20×10×75 mm sheet of stainless steel (FIGS. 19 and 20).

[0194] The cover is repositioned with a PEEK seal at 340° C. and cooled.

[0195] The end pieces (FIGS. 22 and 23) are fixed (FIG. 24) on the column and the assembly is sealed by a film of two-component epoxy glue.

BIBLIOGRAPHY

[0196] [1] K Nakanishi, Phase separation in silica sol-gel system containing polyacrylic acid, Journal of non-crystalline Solids 139 (1992), 1-13 and 14-24; [0197] [2] K. Nakanishi, Phase separation in Gelling Silica-Organic Polymer Solution: Systems Containing Poly(sodium styrenesulfonate), J. Am. Ceram. Soc. 74 (10) 2518-2530-30 (1991); [0198] [3] N. Ishizuka, Designing monolithic double pore silica for high-speed liquid chromatography, Journal of Chromatography A, 797 (1998), 133-137.