DE19910105A1

DE19910105A1 - Porous cellulose matrix in the form of sponge or sponge cloth, obtained by coagulating a mixture of alkaline cellulose carbamate solution, fibrous reinforcing material and solid pore former

Info

Publication number: DE19910105A1
Application number: DE1999110105
Authority: DE
Inventors: Hermann Lang; Fritz Loth
Original assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Current assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Priority date: 1999-03-08
Filing date: 1999-03-08
Publication date: 2000-09-21
Anticipated expiration: 2019-03-09
Also published as: DE19910105C2

Abstract

Sponge or sponge cloth comprising a porous cellulose matrix and reinforcing materials in the form of fibres, non-woven or woven fabric, in which the matrix consists of porous cellulose carbamate (CCB) with a degree of substitution (DS; for carbamate groups) of 0.001-0.3. An Independent claim is also included for a process for the production of a porous cellulose matrix by making a moulding material from an alkaline CCB solution, pore-formers (PF) and reinforcing materials (RM), coagulating this material by heating at 30-100 deg C or in a precipitating bath, without cleavage of carbamate groups or with partial or complete cleavage, then washing and fabricating the resulting shaped porous cellulose body.

Description

Die vorliegende Erfindung betrifft eine poröse Cellu lose-Matrix in Form von Schwämmen oder Schwammtüchern und Verfahren zur Herstellung durch Koagulation von Lösungen eines instabilen Cellulosederivats in Gegen wart von Porenbildnern und einem faserförmigen Ver stärkungsmaterial.The present invention relates to a porous cellu loose matrix in the form of sponges or sponge cloths and method of manufacture by coagulation of Solutions of an unstable cellulose derivative in counter were from pore formers and a fibrous Ver strengthening material.

Das allgemeine Verfahrensprinzip zur Herstellung künstlicher Schwämme aus Regeneratcellulose wurde be reits in den 20er und 30er Jahren des 20. Jahrhun derts entwickelt und patentiert. Es besteht darin, Viskose, d. h. eine Lösung von Cellulosexanthogenat in Natronlauge, mit Fasern und einem Porenbildner zu vermischen, die Mischung in Formen zu gießen oder zu pressen und die Cellulose zu regenerieren (D.R.P. 512 748; R. Vieweg, E. Becker: Kunststoff-Handbuch, Bd. 111 Abgewandelte Naturstoffe. Carl Hanser Verlag, München, 1965). Obwohl zwischenzeitlich auch andere Wege zur Herstellung von Celluloseschwämmen z. B. aus in N-Methylmorpholin-N-oxyd (NMMO) gelöster Cellulose vorgeschlagen wurden (Ch. Schlossnikl, H. Rüf und P. Gspaltl: Celluloseschwämme, Preprint 3. Internationa les Symposium des TITK 2.-3. September 1998, Rudol stadt), basieren die meisten heute angewendeten tech nischen Verfahren der Schwamm- und Schwammtuchher stellung immer noch auf diesem Grundprinzip und der Verwendung von Viskose in zahlreichen Variationen und Verbesserungen, vor allem in bezug auf die technische Gestaltung der Koagulation und die Porenbildung für die Schwammherstellung.The general principle of the manufacturing process artificial sponges made from regenerated cellulose were used already in the 20s and 30s of the 20th century derts developed and patented. It is, Viscose, d. H. a solution of cellulose xanthate in Sodium hydroxide solution, with fibers and a pore former mix, pour or pour the mixture into molds press and regenerate the cellulose (D.R.P. 512 748; R. Vieweg, E. Becker: Kunststoff-Handbuch, Vol. 111 Modified natural products. Carl Hanser Verlag, Munich, 1965). Although in the meantime others too Ways of making cellulose sponges e.g. B. from Cellulose dissolved in N-methylmorpholine-N-oxide (NMMO) were proposed (Ch. Schlossnikl, H. Rüf and P. Gspaltl: cellulose sponges, preprint 3rd internationa les symposium of TITK 2.-3. September 1998, Rudol city), most of the tech used today is based African sponge and sponge cloth processes position on this basic principle and the Use of viscose in numerous variations and Improvements, especially in terms of technical Design of coagulation and pore formation for the sponge production.

Die wesentlichsten Nachteile des Viskoseverfahrens bestehen darin, daß viele aufwendige und zeitraubende Verfahrensschritte notwendig sind, durch die Verwen dung des feuergefährlichen Schwefelkohlenstoffs erheb liche Sicherheitsvorkehrungen getroffen werden müssen und bei der Regenerierung neben Schwefelkohlenstoff auch Schwefelwasserstoff freigesetzt wird. Da es sich bei beiden Verbindungen auch um stark toxische Sub stanzen handelt, entsprechen diese Verfahren nicht mehr den heutigen Vorstellungen und Anforderungen des Umweltschutzes, bzw. es müssen extreme technische Aufwendungen betrieben werden, damit diese Produkte nicht in die Umwelt gelangen sondern zurückgewonnen oder in unbedenkliche Verbindungen umgewandelt wer den.The main disadvantages of the viscose process are that many are complex and time-consuming Procedural steps are necessary through the use of the flammable carbon disulphide safety precautions must be taken and when regenerating alongside carbon disulfide hydrogen sulfide is also released. Since it is both compounds also have a highly toxic sub stamping, these procedures do not correspond more of today's ideas and requirements of Environmental protection, or it must be extremely technical Expenses are operated for these products not get into the environment but recovered or converted into safe connections the.

Die Schwammherstellung mit Hilfe der NMMO-Technologie benutzt ein teures und explosives Lösungsmittel, des sen Rückgewinnung aus verdünnten Abwässern zusätzlich hohe Kosten verursacht. Sponge production using NMMO technology uses an expensive and explosive solvent, the Additional recovery from diluted wastewater causes high costs.

Es ist weiterhin bekannt, daß sich Cellulosecarbamat in Natronlauge auflösen läßt und daß diese Cellulose carbamat-Lösungen einen schlechteren Lösungszustand als das Cellulosexanthogenat in der Viskose aufweist. Dieser schlechtere Lösungszustand wird einmal durch die gegenüber dem Cellulosexanthogenat fehlende anio nische Ladung des Cellulosederivates aber auch da durch hervorgerufen, daß eine Vergleichmäßigung der Substituentenverteilung zwischen den Cellulosemolekü len sowie innerhalb einer Cellulosekette, wie sie in der Viskose während der Nachreife durch Umxanthoge nierung erfolgt, beim Cellulosecarbamat nicht statt findet, d. h. während die Hydrolyse des Cellulosexant hogenates
It is also known that cellulose carbamate can be dissolved in sodium hydroxide solution and that these cellulose carbamate solutions have a worse solution state than the cellulose xanthate in viscose. This poorer state of solution is caused by the lack of anionic charge of the cellulose derivative compared to the cellulose xanthate but also by an equalization of the substituent distribution between the cellulose molecules as well as within a cellulose chain, as occurs in the viscose during maturation by rexanthogenation Cellulose carbamate does not take place, ie during the hydrolysis of the cellulose xanthate

Cell-O-CSS^- Na⁺ + H₂O ↔ Cell-OH + NaOH + CS₂
Cell-O-CSS ^- Na ⁺ + H ₂ O ↔ Cell-OH + NaOH + CS ₂

zum Teil reversibel ist, verläuft die Hydrolyse des Cellulosecarbamates irreversibel:
is partially reversible, the hydrolysis of the cellulose carbamate is irreversible:

Cell-O-CONH₂ + 2H₂O → Cell-OH + NH₄HCO₃ Cell-O-CONH ₂ + 2H ₂ O → Cell-OH + NH ₄ HCO ₃

Diesen schlechteren Lösungszustand, der auch zu einer schnelleren Koagulation der Cellulosecarbamat-Lösun gen und schon zu einer Ausfällung des Cellulosecarba mates beim Spinnen in alkalische Bäder (DE 35 34 370 A1) führt, versucht man deshalb durch gegenüber in der Viskose übliche höhere NaOH-Konzentrationen oder durch löslichkeitsverbessernde Zusätze z. B. Zinkat und/oder Harnstoff zur Löselauge auszugleichen (DE 33 43 156; WO 83/02278; DD 201 908), was aber sowohl höhere Kosten als auch weitere Verfahrensschritte zur Rückgewinnung der Zusätze verursacht. Obwohl die Ver wendung alkalischer Cellulosecarbamat-Lösungen für die Herstellung von Fasern, Folien (DD 201 908, DE 35 34 370 A1) und Celluloseperlen (DD 259 533 A3) be kannt ist, existieren keine Hinweise über ihre Ver wendung zur Herstellung von Schwämmen und Schwammtü chern. Vielmehr mußte davon ausgegangen werden, daß die sehr koagulationsempfindlichen Cellulosecarbamat- Lösungen, beim Zusatz von Salzen erstarren und sich dann nicht mehr verarbeiten lassen.This worse solution state, which also leads to a faster coagulation of the cellulose carbamate solution gen and already to a precipitation of the cellulose carba mates when spinning in alkaline baths (DE 35 34 370 A1) leads, therefore one tries through opposite in the viscose usual higher NaOH concentrations or through solubility-improving additives e.g. B. zincate and / or to compensate urea to the solvent solution (DE 33 43 156; WO 83/02278; DD 201 908), but what both higher costs as well as further process steps for Recovery of additives caused. Although the Ver use of alkaline cellulose carbamate solutions for the production of fibers, foils (DD 201 908, DE 35 34 370 A1) and cellulose beads (DD 259 533 A3) is known, there are no indications of their ver application for the production of sponges and sponge door chern. Rather, it had to be assumed that the very coagulation-sensitive cellulose carbamate Solutions, solidify with the addition of salts and themselves then no longer have it processed.

Die Aufgabe der vorliegenden Erfindung ist es, aus alternativen Celluloselösungen Schwämme oder Schwamm tücher herzustellen ohne giftige oder explosive Stof fe zu benutzen oder entstehen zu lassen aber ähnliche Eigenschaften der aus Viskose hergestellten Cellulo seschwämme zu gewährleisten.The object of the present invention is to alternative cellulose solutions sponges or sponge to manufacture cloths without toxic or explosive substances to use or create fe but similar ones Properties of the cellulo made from viscose to ensure sponges.

Die Aufgabe wird in bezug auf die poröse Matrix durch die kennzeichnenden Merkmale des Patentanspruches 1 und in bezug auf das Verfahren durch die Merkmale des Patentanspruches 6 gelöst. Die Unteransprüche zeigen vorteilhafte Weiterbildungen auf.The task is accomplished with respect to the porous matrix the characterizing features of claim 1 and in relation to the method by the features of Claim 6 solved. The subclaims show advantageous further training.

Erfindungsgemäß wird somit vorgeschlagen, daß die Cellulose-Matrix aus Cellulosecarbamat besteht, wobei der Substitutionsgrad der Cellulose an Carbamatgrup pen in der porösen Cellulosecarbamat-Matrix zwischen 0,001 und 0,3 liegt. Die Formmasse aus der die poröse Matrix hergestellt wird, besteht bevorzugt aus einem Teil Cellulose in Form von gelöstem Cellulosecarbamat 0,1-1 vorzugsweise 0,3-0,6 Teile Verstärkungsma terial und 1-50 vorzugsweise 5-40 Teile Poren bildnern. Bei den Porenbildnern ist es bevorzugt, wenn diese aus einem festen Salz bestehen. Beispiele für solche Salze sind Kristallsoda, Glaubersalz, Am moniumsalze der Kohlen- und der Carbaminsäure.According to the invention it is thus proposed that the Cellulose matrix consists of cellulose carbamate, wherein the degree of substitution of the cellulose on carbamate group pen in the porous cellulose carbamate matrix between 0.001 and 0.3. The molding compound from which the porous Matrix is produced, preferably consists of a Part of cellulose in the form of dissolved cellulose carbamate 0.1-1 preferably 0.3-0.6 parts of reinforcement material and 1-50 preferably 5-40 parts of pores educators. In the case of the pore formers, it is preferred if they consist of a solid salt. Examples for such salts are crystal soda, Glauber's salt, Am monium salts of carbonic and carbamic acid.

Beispiele für Verstärkungsmaterialien sind: natürliche Cellulosefasern und Regeneratcellulosefa sern in Form von ungeordneten Faserbeimischungen so wie als Vlies, Kettfaserlage, Gewebe oder Gewirke.Examples of reinforcement materials are: natural cellulose fibers and regenerated cellulose fa so in the form of disordered fiber admixtures such as fleece, warp fiber, woven or knitted fabrics.

Zur Naßfestigkeitserhöhung sind auch Faseranteile insbesondere in den Kettfaserlagen, Geweben oder Ge wirken aus Synthesefasern einsetzbar.Fiber components are also used to increase the wet strength especially in the warp fiber layers, fabrics or Ge can be used from synthetic fibers.

Die Erfindung betrifft weiterhin ein Verfahren zur Herstellung von porösen Cellulosematrizes, Erfin dungsgemäß wird das Verfahren so durchgeführt, daß man als Celluloselösung eine alkalische Cellulosecar bamat-Lösung verwendet, diese in bekannter Weise in Gegenwart von festen Salzen oder anderen Porenbild nern wie Zucker oder ein Gas entwickelnden Stoffen mit einem faser-, vlies-, oder gewebeförmigen Ver stärkungsmaterial kombiniert, in eine geeignete Form bringt, und durch Erhitzen auf 30-100°C, bevorzugt 40-80°C, oder durch saure Bäder koaguliert. Über raschenderweise wurde gefunden, daß Cellulosecarba mat-Lösungen in der Kälte, d. h. bei 5 bis -10°C, selbst gegenüber großen Salzmengen stabil sind, wenn die Salze in fester Form zugegeben werden. Die Cellu lose kann dabei wie bei der Herstellung der Schwämme aus Viskose vollständig regeneriert werden oder die Carbamatgruppen bleiben vollständig oder zum Teil an der Cellulose erhalten und vergrößern so durch die höhere Wasseraufnahme bei der Quellung des Cellulose carbamates gegenüber der unsubstituierten Cellulose die direkt vom Schwamm-Material und unabhängig von dem in den Poren befindlichen Wasser aufgenommene Wassermenge. Die so gewonnenen porösen Formkörper werden dann in bekannter Weise gewaschen und in Ge genwart eines Weichmachers getrocknet.The invention further relates to a method for Manufacture of porous cellulose matrices, inven According to the method is carried out so that an alkaline cellulose car is used as the cellulose solution bamat solution used in a known manner Presence of solid salts or other pore structure like sugar or gas-evolving substances with a fiber, fleece, or fabric-shaped Ver Reinforcement material combined, in a suitable form brings, and by heating to 30-100 ° C, preferred 40-80 ° C, or coagulated through acid baths. About It was surprisingly found that cellulose carba mat solutions in the cold, d. H. at 5 to -10 ° C, are stable even with large amounts of salt, if the salts are added in solid form. The Cellu Loose can be made like in the production of the sponges be completely regenerated from viscose or the Carbamate groups remain in whole or in part maintain and enlarge the cellulose by higher water absorption when the cellulose swells carbamates compared to the unsubstituted cellulose which directly from the sponge material and regardless of the water in the pores Amount of water. The porous shaped bodies obtained in this way are then washed in a known manner and in Ge dried in the presence of a plasticizer.

Die Erfindung soll an nachfolgenden Beispielen näher erläutert werden, ohne sie dadurch einzuengen.The invention is illustrated by the following examples are explained without restricting them.

Embodiments

1. In a cellulose carbamate solution containing 8% cellulose carbamate with a DS of 0.325 and a Cuoxam-DP of 379 and 7.8% NaOH, the cotton fibers and solid Na 2 CO 3 .10 H 2 were at 0 ° C O mixed in. The molding composition thus obtained contained 0.5 part of cotton fibers and 9.3 parts of Na 2 CO 3 .10 H 2 O on 1 part of cellulose in the form of dissolved cellulose carbamate, the grain size or the grain size distribution of this salt being purely due and for which Pore structure in the sponge is not optimal. This mixture was coagulated to a sponge at 100 ° C for 8 hours. The sponge was washed out with water, neutralized with acid and washed again. After drying, its water intake was determined. The sponge thus produced absorbed 86.8% of its dry weight of water. The nitrogen content of the porous matrix was 0.094%, corresponding to an average degree of substitution of 0.0109.
2. A sponge was produced according to Example 1 from a molding composition according to Example 1, which contained 0.5 part cotton fibers and 14.3 parts Na 2 CO 3 .10 H 2 O per 1 part dissolved cellulose. This sponge absorbed 122.1% water. The nitrogen content of the porous matrix was 0.058% corresponding to an average degree of substitution of 0.0067.
3. From a molding composition according to Example 1, which contained 0.5 part cotton fibers and 17.9 parts Na 2 CO 3 .10 H 2 O per 1 part dissolved cellulose, a sponge was prepared according to Example 1, which absorbed 57.6% water . The nitrogen content of the porous matrix was 0.082%, corresponding to an average degree of substitution of 0.0095.
4. From a molding composition according to Example 3 was followed by Coagulation in a sulfuric acid, sodium sul fat bath (Müller-Bad) and subsequent Wash out a sponge cloth that made 150.9% water absorbed. The nitrogen content of the porous matrix was 1.431% corresponding to one average degree of substitution of 0.1733.
5. From a cellulose carbamate solution according to Example 1 with 7.8% cellulose carbamate and 7.8% NaOH, a molding composition was prepared at -5 ° C, the 0.5 part cotton fibers and 17.9 parts solid to 1 part of dissolved cellulose Na 2 SO 4 .10 H 2 O contained, whereby the grain size or the grain size distribution of this salt is purely random and is not optimal for the pore structure in the sponge. This molding composition was coagulated at 80 ° C, washed and dried. The sponge thus obtained took up 178.2% water. The nitrogen content of the porous matrix was 0.09% corresponding to an average degree of substitution of 0.0104 carbamate groups.
6. From the molding composition according to Example 5 was after Example 4 made a sponge cloth that 120.7% water absorbed. The nitrogen content of the porous matrix was 1.672% corresponding to one average degree of substitution of 0.204 on carbamate groups.
7. Comparative example:
A viscose of 7.7% cellulose and 6.3% alkali content was used to produce a molding compound containing 0.5 part cotton fibers and 17.9 parts solid Na 2 SO 4 .10 H 2 O from 1 part dissolved cellulose same grain size distribution as in Examples 5 and 6. A sponge cloth was prepared from this molding composition according to Example 6, which absorbed 143.6% water.

Claims

1. Porous cellulose matrix in the form of sponges or sponge cloths consisting of a porous cellulose matrix and fiber, non-woven, or tissue-shaped reinforcing materials, characterized in that the matrix is a cellulose carbamate matrix with a DS of cellulose on carbamate groups in the porous cellulose carbamate matrix of 0.001-0.3.

2. Porous cellulose matrix according to claim 1, characterized characterized that the matrix from a shape containing a part of cellulose in Form of dissolved cellulose carbamate 0.1-1 preferably 0.3-0.6 parts of reinforcing material and 1-50 preferably 5-40 parts pore structure has been preserved.

3. Porous cellulose matrix according to claim 2, characterized characterized in that the pore formers solid salts are.

4. Porous cellulose matrix according to claim 3, characterized characterized in that the solid salts are selected are made of crystal soda, Glauber's salt, ammonium salt ze of carbonic and carbamic acid or their Mixtures.

5. Porous cellulose matrix after at least one of claims 1 to 4, characterized in that the reinforcing materials are selected made from natural cellulose fibers and regenerate cellulose fibers in the form of disordered fibers admixtures as well as fleece, warp fiber layer, Woven or knitted fabrics or their mixtures.

6. Process for making a porous cellulo se matrix from a cellulose solution with Ver strengthening materials and pore formers, thereby characterized in that a molding compound from a alkaline cellulose carbamate solution, pore structure ners and reinforcement material, this Molding compound by heating to 30-100 ° C and / or coagulated in a precipitation bath, the carbamate do not group, partially or completely split off tet and the resulting porous cellulose Molded body washes and assembled.

7. The method according to claim 6, characterized in net that one for the preparation of the alkaline Cellulose carbamate solution with cellulose carbamate a degree of substitution of 0.1-0.5, preferably used 0.15-0.4.

8. The method according to claim 6 or 7, characterized ge indicates that the production of the alk Mix cellulose carbamate solution cellulose car bamat with an average degree of polymerization from 200-800, preferably 300-600 used.

9. The method according to at least one of claims 6 to 8, characterized in that the cellulo Secarbamate concentration in the solution 2-10 Mass% is.

10. The method according to at least one of claims 6 to 9, characterized in that the cellulo secarbamate in sodium hydroxide solution with a NaOH concentrate tration of 5-12 mass% is solved.

11. The method according to at least one of claims 6 to 10, characterized in that a shape mass is used on a part of Cellu loose in the form of dissolved cellulose carbamate x-y Parts of reinforcement materials and z-k parts Contains pore formers.

12. The method according to at least one of claims 6 to 11, characterized in that the coagula tion achieved by heating to 40-80 ° C becomes.

13. The method according to at least one of claims 6 to 11, characterized in that the coagula tion is achieved by acid baths.

14. The method according to at least one of claims 6 to 13, characterized in that the cellulo secarbamat solution further solution-improving Contains substances such as zincate and / or urea.

15. The method according to at least one of claims 6 to 13, characterized in that salts are used as pores, preferably Na ₂ SO ₄ , Na ₂ CO ₃ and / or ammonium salt of carbonic acid and carbamic acid.