# US 9,518,345 B2 · Method for producing a spinnable silica sol material

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- Number: US 9,518,345 B2
- Document ID: US9518345B2
- Status: Granted
- Kind: B2
- Application number: 14/232,857
- Filed: 2012-07-17
- Published: 2014-06-12
- Granted: 2016-12-13
- Earliest claimed: 2011-07-21
- Assignees: Jiangsu Synecoun Medical Technology Co., Ltd
- Applicants: Ekkehard Barth; Bastian Mahr
- Inventors: Ekkehard Barth; Bastian Mahr
- Web page: https://patentgrep.com/patent/US9518345B2

## CPC

- D04H 3/004: Glass yarns or filaments
- B29C 55/005: {characterised by the choice of materials}
- C01B 33/148: Concentration; Drying; Dehydration; Stabilisation; Purification {(C01B33/1465 takes precedence)}
- C04B 35/6224: {Fibres based on silica}
- C04B 35/624: Sol-gel processing
- C04B 35/6263: {characterised by their solids loadings, i.e. the percentage of solids}
- C04B 35/62635: {Mixing details}
- C04B 35/62685: {characterised by the order of addition of constituents or additives}
- C08G 77/02: Polysilicates
- C08L 77/02: Polyamides derived from omega-amino carboxylic acids or from lactams thereof (C08L77/10 takes precedence)
- D01D 5/12: Stretch-spinning methods ({D01D5/098 takes precedence} finishing by stretching D02J1/22)
- C01B 33/14: Colloidal silica, e.g. dispersions, gels, sols
- C01B 33/143: of aqueous solutions of silicates
- C04B 2235/3418: Silicon oxide, silicic acids or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint
- C04B 2235/441: Alkoxides, e.g. methoxide, tert-butoxide
- Y10T 442/60: Nonwoven fabric [i.e., nonwoven strand or fiber material]
- D04H: MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL (weaving D03; knitting D04B; braiding D04C; net-making D04G; sewing D05B; tufting D05C; finishing non-woven fabrics D06); FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING {; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION}(non-woven fabrics having an intermediate or external layer of a different kind, e.g. of woven fabric, B32B)
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- D01D: MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

In a process for producing a spinnable silica sol material, a viscosity value VS is stipulated which the spinnable silica sol material should have after ripening. A viscosity value VR corresponding to VS which the silica sol material has before ripening is ascertained. An aqueous acid solution and a hydrolysable silicon compound are combined. The combined mixture is evaporated to give a single-phase solution while measuring the viscosity of the mixture and the evaporation process is terminated upon reaching the viscosity value VR. The single-phase solution thus obtained is then ripened to give a silica sol material with the viscosity value VS. The process exhibits reduced waste and more exact reproducibility of the spinning sol properties during the synthesis and an increased space-time yield in the production of biologically degradable and/or resorbable fibers and nonwoven fabrics.

## Claims

### Claim 1

A process for producing a spinnable silica sol material comprising:
(a) stipulating a viscosity value VS, which the spinnable silica sol material should have after ripening, wherein the stipulated viscosity value VS is in the range from 30 to 100 Pa·s at a shear rate of 10 s−1 at 4° C.,
(b) ascertaining a viscosity value VR corresponding to VS, which the silica sol material has before ripening,
(c) combining an aqueous acid solution and a hydrolysable silicon compound, wherein the combining in (c) takes place under quasi-isothermal conditions over a period of at least 15 minutes, and wherein, in (c), the hydrolysable silicon compound is metered into an acid located in a solvent in parallel in a controlled manner,
(d) evaporating a mixture combined in (c) to give a single-phase solution while measuring the viscosity of the mixture and terminating evaporation process upon reaching the viscosity value VR,
(e) ripening a single-phase solution obtained in (d) to give a silica sol material with the viscosity value VS, wherein the ripening in (e) is carried out at temperatures of from 25° C. to 35° C., and wherein the single-phase solution is stirred;
wherein the viscosity values VS and VR are dynamic viscosities, which are correlative and measured online and inline continuously by measurement probes within the mixture.

### Claim 2 (depends on 1)

The process according to claim 1, where the combining in (c) takes place such that heat released by hydrolysis-condensation reaction is used for heating a synthesis mixture.

### Claim 3 (depends on 1)

The process according to claim 1, where the hydrolysable silicon compound is a silicon compound of formula (I)
SiX4 (I)
and X in formula (I) is an optionally substituted straight-chain and/or branched C1-C5 alkoxy radical.

### Claim 4 (depends on 1)

The process according to claim 1, where (d) is carried out in a closed apparatus in which thorough mixing is possible and in which at the same time, any solvent present can also be evaporated.

### Claim 5 (depends on 1)

A spinnable silica sol material obtained by a process according to claim 1.

### Claim 6 (depends on 1)

The process of claim 1, wherein the quasi-isothermal conditions are within a bottom temperature range of ±5° C.

### Claim 7 (depends on 1)

The process of claim 1, wherein the quasi-isothermal conditions are within a bottom temperature range of ±2° C.

### Claim 8 (depends on 1)

The process of claim 1, wherein the quasi-isothermal conditions are within a bottom temperature range of ±0.5° C.

### Claim 9 (depends on 1)

The process of claim 1, wherein the ripening in (e) is carried out at temperatures of from 28.1° C. to 35° C.

### Claim 10 (depends on 1)

The process of claim 1, wherein the hydrolysable silicon compound comprises tetraethoxysiloxane.

### Claim 11 (depends on 1)

The process of claim 1, wherein the solvent comprises ethanol.

### Claim 12 (depends on 1)

The process of claim 1, wherein the viscosity values VS and VR are in a linear relationship.

### Claim 13 (depends on 1)

The process for producing a fibre and/or a nonwoven fabric, comprising producing a spinnable silica sol material according to claim 1; and
(f) drawing threads from the ripened silica sol material from (e) and, in the case of a nonwoven fabric, assembling threads to give a nonwoven fabric.