DE10053359A1 - Cellulose fiber or film production with neutral adsorbent properties, for use e.g. in air filters, involves wet-spinning solution in aqueous tert. amine oxide containing cellulose and finely-divided neutral adsorber - Google Patents

Abstract

In the production of formed cellulose products with high neutral adsorbent properties by the extrusion of a 5-20 wt% solution of cellulose in an aqueous tert. amine oxide, followed by drawing and precipitation, the solution used also contains 0.01-300 wt.% (based on cellulose) of a neutral adsorber with a grain size of not more than 100 microns m. The production of formed cellulose products with high neutral adsorbent properties by dry-wet extrusion involves making a 5-20 wt.% solution of cellulose in aqueous tert. amine oxide which also contains 0.01-300 wt.% (based on cellulose) of a neutral adsorber (I) with a grain size of not more than 100 microns m, then extruding the solution, drawing in a non-precipitating medium and precipitating the product in a suitable bath. An Independent claim is also included for composite materials comprising at least partly of fibers obtained by the above method, especially tow, non-woven fabric, paper or felt.

Description

The invention relates to a process for the production of moldings neutral adsorbing properties after dry Wet extrusion process by forming a solution of 5 to 20% by mass Cellulose in a water-containing tertiary amine oxide, extruding the solution, Warping of the extrudate in a non-precipitating medium and failure of the Shaped body in an aqueous precipitation bath. The invention also relates to a Composite made from the method according to the invention Shaped bodies, in particular fibers, and its use as a filter material.

It is known to use cellulosic moldings, in particular fibers and films manufacture by a solution of cellulose in amine oxide hydrate, preferably deformed into N-methylmorpholine-N-oxide monohydrate and with a Non-solvent for the cellulose, preferably water, is coagulated. Through different shapes and simultaneous orientation of the Cellulose molecules are products with a wide range of uses in textiles and technical areas of application.

In the patent application PCT / DE 00/00917 is the production of moldings described with high ion exchange capacity. These moldings contain Ion exchangers and therefore have comparable properties. When in use macroporous styrene-divinylbenzene copolymer with trialkylammonium Groups show these shaped bodies in addition to ion exchange properties an unspecific adsorption for organic molecules. The non-specific Adsorption of these ion exchangers is due to the pore size and inner surface limited.

WO 95/35044 includes a cigarette filter made of a fiber composite Lyocell staple fibers are known. This filter is used to remove tar and Solid particles from the smoke stream. The filter material contains no active ones Groups capable of adsorbing polar or non-polar molecules are.  

The invention has for its object a method for producing compared to cellulosic moldings with high adsorption capacity to create polar and non-polar molecules. Furthermore, a procedure is said created for the production of moldings, in particular fibers and films are due to their high adsorption capacity for polar and non-polar organic molecules are suitable for the production of filter material. Furthermore, a composite material is to be created from these shaped bodies, that as filter material in cigarettes, as an air or water filter and in others Areas of application is applicable. Further advantages result from the following description.

This object is achieved according to the invention in the method mentioned at the outset solved in that a solution with 0.5 to 300 mass%, based on Cellulose, at least one neutral adsorber with a grain size of ≦ 100 µm extruded.

Substances are used as neutral adsorbers for the purposes of the present invention understood that on their surface by physisorption (van der Waals forces, Dipole-dipole interactions) other substances by covering their outer or enrich the inner surface.

Surprisingly, it was found that those produced in the Shaped neutral absorber for the from aqueous solutions, Gases or vapors to be adsorbed polar and / or non-polar Molecules are very accessible, even though the embedding of active substances in matrices generally with a decrease in activity of these substances connected is. The adsorption capacity depends on the content and the Type of neutral adsorber physically embedded in the cellulose matrix. For example, the molded body according to the invention, consisting of the same Parts by weight of cellulose and neutral adsorber 50% of the adsorption capacity of the commercial neutral adsorber without added cellulose. The Adsorption capacity is not due to the spinning process or the embedding demonstrably impaired.  

According to the preferred embodiment of the method according to the invention contains the solution used for extrusion 1 to 200 mass%, preferably 10 to 150% by mass, based on cellulose, of the neutral adsorber. Especially Preferred solutions are those based on cellulose 30 to 100 mass% Neutral adsorber included.

The grain size of the neutral adsorbers is preferably in the range ≦ 15 μm. Basically, there is no limit to the lower limit of the Grain size of suitable neutral adsorbers. Only suitable ones are exemplary Screen lines with grain sizes of ≦ 0.05 µm, 0.1 µm, 0.5 µm and 1 µm are mentioned.

Commercial neutral adsorbers can be used However, the grain size is generally far above that according to the invention Range. The grain size required for incorporation into the solution can be achieved by grinding the commercially available neutral adsorbers. The grain size of the neutral adsorbers is expediently established Grinding and classifying in a fluid bed counter jet mill with Turboplex Fine sighting. Another possibility is wet grinding in pearl mills with subsequent filtration or screening.

The formation of the extrudable solution loaded with the neutral adsorber can be done in different embodiments. At a Embodiment disperses the neutral adsorber in the one already formed Cellulose solution. In a further embodiment, one is first formed Mixture of cellulose, amine oxide and water, constitutes a suspension of the Neutral adsorbers in water or a mixture of water and amine oxide forth and adds the suspension of the mixture mentioned and transfers it by distilling water into the cellulose solution. This procedure has the advantage that the formation of the suspension of the finely divided neutral adsorber in water or a mixture of water and amine oxide is more easily possible than the dispersion in the cellulose solution formed. If necessary, the Suspension in water can be supported by adding a surfactant.  

In a third embodiment, the cellulose and the Neutral adsorber in a mixture of amine oxide and water and then forms from the suspension by water evaporation to the monohydrate level Cellulose solution. In all three cases the neutral adsorber can be uniform Product represent or a mixture of several different built-up neutral adsorbers. The neutral adsorber is in the Cellulose solution is insoluble and becomes when the cellulose is precipitated into it stored, with such a structure that the neutral adsorber for the substances to be adsorbed remains accessible.

In general, fibers are produced by the process according to the invention, Filaments or foils. It can be round or profiled Nozzle holes, hollow nozzles or slot nozzles can be worked. The preferred solvent in the process according to the invention N-methyl-N-oxide monohydrate.

The precipitated molded body is then used to remove the amine oxide washed with clean water and dried.

By grinding and dispersing the neutral adsorbers in the Extrusion solution can be molded articles, in particular fibers, filaments or Films are created depending on the pore size and their Polarity a very wide range of organic and inorganic molecules adsorb. So z. B. by dispersing activated carbon a molded body are generated by the diverse adsorptive possibilities of activated carbon has. Such moldings can be used for water purification and gas and Air purification can be used.

When organic vapors are removed from gases, adsorption is present Activated carbon has the advantage that it is good even at very low partial pressures Effect is achieved. Polymer adsorber, macroporous and microporous styrene Divinyl copolymers and also the carbonized form of these resins show similar adsorption behavior as the activated carbons. Become alkali or Alkaline earth aluminum silicates with due to the crystal lattice structure Cavities of a defined size, so-called molecular sieves, used  moldings are obtained which are selective according to molecular size or polarity adsorb. Adsorb these adsorbers from the zeolite group prefers polar substances over polarizable or non-polar substances.

Activated carbon and the polymer adsorber alone or in combination with Molecular sieves reduce the toxic compounds of the Cigarette smoke. From the multitude of these connections the most important ones are in the gas phase carbon monoxide, nitrogen oxides, hydrogen cyanide, formaldehyde, Acetaldehyde, pyridine and volatile nitrosamines.

Dispersing silica gel in the solution gives shaped articles which preferentially adsorb polar substances and especially water. This Shaped bodies can be used for different drying processes, such as B. removing water traces from solvents.

The task is further achieved by a composite material, in particular as a tow, fleece, Paper or felt, dissolved, which is at least partially made according to the process of Claims 1 to 14 produced fibers. This composite can made entirely from the invention and loaded with neutral adsorbers Lyocell fibers exist. The composite can also be based on a mixture with different neutral adsorbers (activated carbon, polymer adsorber, Molecular sieves, silica gel) modified cellulosic fibers, where a composite with effects similar to that obtained when a Load fiber material with two or more different neutral adsorbers becomes. Finally, it is also possible to use a composite material according to the invention with fibers loaded with neutral adsorbers and from normal lyocell fibers or other fibers such as As polyethylene, polypropylene or pulp, in one To produce wet nonwoven process, whereby nonwovens can be graded Receives filter efficiencies. Under the tow mentioned above is a crimped one Understand sliver from many individual filaments.

The composite according to the invention is suitable for use as Filter material for the removal of non-polar and polar connections Solutions, gases and vapors. The area of use in the gas phase  includes in particular filters for cigarettes, filters for motor vehicles, accessories and Exhaust air filter and solvent recovery filter. For adsorption in In the liquid phase, the use as a drinking water filter should be mentioned. The Filtration of drinking water leads to the reduction of pesticides, Chlorine and ozone.

Another application is the removal of traces of water Solvents that can be easily solved with these filters. The neutral adsorbers used according to the invention are solid substances that only stored in the cellulose matrix, but not dissolved. There are therefore none for these neutral adsorbers by the solubility in of the spinning or extrusion solution given quantitative Restrictions.

To further clarify the method according to the invention and for the use of the process products relevant properties serve the following examples:

example 1

A 9 mass% cellulose solution in N-methylmorpholine-N-oxide monohydrate becomes a powdered activated carbon with a grain size ≦ 15 µm in one Weight fraction of 100% by mass, based on the cellulose fraction, added. This spinning solution is homogenized in a kneader and at a Temperature of about 90 ° C spun through a spinneret with 150 holes. The Take-off speed is 25 m / min. The multifilament becomes through several wash baths performed to remove the N-methylmorpholine-N-oxide. The thread is cut into 6 mm stacks, dried at approx. 80 ° C or leave centrifugally moist.

The fibers have a titer of 0.7 tex, an elongation of 14.2% and a Tensile strength of 7.5 cN / tex. As a measure of the assessment of adsorption performance was the adsorption of carbon tetrachloride at saturation concentration and 20 ° C used in equilibrium. The fiber described in Example 1 has an adsorption capacity of 0.44 g carbon tetrachloride per g fiber.  

Example 2

A cellulose mash in 60% N-methylmorpholine-N-oxide becomes one aqueous suspension of a neutral adsorber based on a carbonized, highly sulfonated styrene-divinyl copolymer in such a Concentration added that the spinning solution 10% by mass cellulose and based on the cellulose content contains 100% by mass of the neutral adsorber. The grain size of the suspended neutral adsorber was ≦ 15 µm. After this Distilled off the water until the N-methylmorpholine-N-oxide monohydrate and the dissolution of the cellulose becomes the spinning solution according to Example 1 spun. The thread is cut into 6 mm stacks at about 80 ° C leave to dry or spin dry. The fibers have a titer of 0.67 tex, an elongation of 15.3% and a tear strength of 6.90 cN / tex. The Adsorption performance of these fibers was 0.90 g carbon tetrachloride per g Fiber.

Example 3

A cellulose mash in 60% N-methylmorpholine-N-oxide becomes one Suspension of a molecular sieve from the group of zeolites in 60% N- Methylmorpholine-N-oxide added that the spinning solution 9% mass% Cellulose and based on the cellulose content 70% by mass of Contains molecular sieve. The particle size of the suspended molecular sieve was at ≦ 15 µm. After distilling off the water to the NMMO Monohydrate and the dissolution of the cellulose becomes the spinning solution after Example 1 spun. The thread is cut into 6 mm stacks at approx. Leave to dry at 80 ° C or spin dry. The fibers have a titer of 0.50 tex, an elongation of 10.1% and a tensile strength of 14.2 cN / tex. The Adsorption capacity of these fibers was 0.31 g carbon tetrachloride per g Fiber.

Example 4

A cellulose mash in 60% N-methylmorpholine-N-oxide becomes one Suspension consisting of 50% molecular sieve and 50% of an activated carbon in 60% N-methylmorpholine-N-oxide added that the spinning solution 9% % By mass of cellulose and based on the proportion of cellulose 100% by mass of the above. Contains mixture of neutral adsorber. The grain size of the suspended Neutral adsorber mixture was ≦ 15 µm.

After distilling off the water to the NMMO monohydrate and Dissolving the cellulose, the spinning solution according to Example 1 is spun. After the N-methylmorpholine-N-oxide had been washed out, the thread was turned into Pile cut to 6 mm, dried at 80 ° C or spin-damp leave. The fibers have a titer of 0.80 tex, an elongation of 13.6% and a tensile strength of 9.5 cN / tex. The adsorption capacity of these fibers was at 0.45 g carbon tetrachloride per g fiber.

Example 5

A 9 mass% cellulose solution in N-methylmorpholine-N-oxide monohydrate becomes a powdery polymer adsorber based on macroporous Styrene-divinyl copolymer and a grain size of ≦ 15 µm in one Weight fraction of 100% by mass, based on the cellulose fraction, added. This spinning solution was spun as described in Example 1 and the Thread cut into 6 mm stacks, dried at approx. 80 ° C or leave centrifugally moist. The fibers have a titer of 0.80 tex, one Elongation of 13.1% and a tensile strength of 10.5 cN / tex. The Adsorption capacity of these fibers was 0.78 g carbon tetrachloride per g Fiber.

Example 6

An 8 mass% cellulose solution in N-methylmorpholine-N-oxide monohydrate becomes a powdered silica gel with a grain size of ≦ 15 µm in one  Weight fraction of 100% by mass, based on the cellulose fraction, added. This spinning solution was spun as described in Example 1 and the Thread cut into 6 mm stacks, dried at approx. 80 ° C. The fibers have a titer of 0.50 tex, an elongation of 16.2% and a tensile strength of 8.6 cN / tex. The adsorption capacity of these fibers was 0.41 g Carbon tetrachloride per g fiber.

Example 7

A spinning solution prepared according to Example 6 is at a temperature of approx. 90 ° C through a slot nozzle to a film with a thickness of about 40 microns in deformed dried state. The nozzle slot has a length of 62.8 mm and the distance from the nozzle to the aqueous precipitation bath was 12 mm. The one from the After the air gap, the film emerging from the nozzle was passed through 2 water baths of 6 m Length guided and wound up. The film was dried at 60 ° C. The adsorption capacity of this film was 0.39 g carbon tetrachloride per g Foil.

Example 8

A 9% by mass cellulose solution in N-methylmorpholine-N-oxide monohydrate is added to a powdery activated carbon with a grain size of ≦ 15 µm in a proportion by weight of 100% by mass, based on the proportion of cellulose. This spinning solution was spun as described in Example 1. The thread is cut into 6 mm stacks and left centrifugally moist. The fibers have a titer of 0.70 tex, an elongation of 14.2% and a tensile strength of 7.5 cN / tex. This fiber is mixed with 10% by mass of cellulose and 10% by mass of polyethylene fibrids and processed in a wet fleece system to form a fleece with a basis weight of 30 g / m ² . The adsorption capacity of this fleece is 0.42 g carbon tetrachloride per g fleece.

Example 9

Fibers produced according to Example 4 are cut to a stack length of 6 mm and left centrifugally moist. The fibers have a titer of 0.80 tex, an elongation of 13.6% and a tensile strength of 9.5 cN / tex. This fiber is mixed with 15% by mass of cellulose and 5% by mass of polyethylene fibrids and processed in a wet fleece system to form a fleece with a basis weight of 30 g / m ² . The adsorption capacity of this fleece is 0.40 g carbon tetrachloride per g fleece.

Claims (17)

1. A process for the production of cellulosic moldings with high neutral adsorbing properties by the dry-wet extrusion process by forming a solution of 5 to 20% by mass of cellulose in a water-containing, tertiary amine oxide, extruding the solution, drawing the extrudate in a non-precipitating medium and precipitating the shaped body in an aqueous precipitation bath, characterized in that the solution contains 0.01 to 300% by mass, based on cellulose, of at least one neutral adsorber with a particle size of ≦ 100 µm. 2. The method according to claim 1, characterized in that the solution 1 to 200 mass%, preferably 10 to 150 mass%, based on Cellulose, the neutral adsorber contains. 3. The method according to claim 1 or 2, characterized in that the Grain size of the neutral adsorber is in the range ≦ 25 µm. 4. The method according to any one of claims 1 to 3, characterized in that the neutral adsorber activated carbon or carbonized styrene-divinyl Are copolymers. 5. The method according to any one of claims 1 to 3, characterized in that the neutral adsorber micro- or macroporous polymer adsorber the basis of styrene-divinyl copolymer. 6. The method according to any one of claims 1 to 3, characterized in that the neutral adsorber is a molecular sieve from the crystallographic Group of zeolites is. 7. The method according to any one of claims 1 to 3, characterized in that the neutral adsorber is a silica gel. 8. The method according to any one of claims 1 to 7, characterized in that the neutral adsorber is dispersed in the cellulose solution. 9. The method according to any one of claims 1 to 7, characterized in that one forms a mixture of cellulose, amine oxide and water, the Neutral adsorber suspended in water or amine oxide, the suspension  added to the mixture and this by distilling water into the Solution transferred. 10. The method according to any one of claims 1 to 7, characterized in that that the cellulose and the neutral adsorber in a mixture Amine oxide and water and suspended from the suspension Evaporation of water forms the solution of cellulose. 11. The method according to any one of claims 1 to 10, characterized in that that the solution at least one predominantly polar and at least contains a predominantly non-polar neutral adsorber. 12. The method according to any one of claims 1 to 11, characterized in that one produces fibers, filaments or foils. 13. The method according to any one of claims 1 to 12, characterized in that that you have a cellulose solution in N-methylmorpholine-N-oxide monohydrate forms. 14. The method according to any one of claims 1 to 13, characterized in that that the grain size of the neutral adsorber by grinding and Sifting in a fluid bed counter jet mill with turbo fine sifting or by wet grinding in pearl mills. 15. Composite, in particular tow, fleece, paper or felt, the least partially made according to the method of any one of claims 1 to 14 manufactured fibers. 16. Use of the composite according to claim 15 as a filter for Removal of non-polar and polar connections from solutions, Gases and vapors. 17. Use according to claim 16 as a filter in cigarettes, as an air filter in the Automotive industry or in household machines.