JP5110477B2 - Fiber sheet with liquid-liquid separation function - Google Patents

Description

  The present invention has a separation function material used when a liquid mixture is separated by a pervaporation method, particularly a liquid-liquid separation function for selectively separating a mixture of a water-soluble organic solvent and water by a pervaporation method. It relates to a fiber sheet.

  As a method for selectively separating water or organic matter from a solution in which water and organic matter are uniformly mixed, a distillation method is widely used. On the other hand, ethanol, isopropanol, butanol, etc., when mixed with water, become azeotropic at a certain concentration or higher, so they cannot be separated by a normal distillation method and use harmful entrainers such as benzene. It is necessary to use the azeotropic distillation method. However, the azeotropic distillation method requires a harmful third component as described above, and also increases the energy cost. Therefore, an alternative separation method is required.

  As an alternative to the azeotropic distillation method, a pressure swing adsorption method (PSA method) has been proposed (Patent Document 1). This is done by injecting a water-containing organic solvent into a container containing hydrophilic zeolite, removing it after adsorbing moisture during the pressurization process, then removing the adsorbed water during the pressure-reduction process, and again injecting the water-containing organic solvent into the water. By repeating the step of removing, the organic solvent is concentrated to a desired concentration. This method is effective for dehydration from an organic solvent having a water content of 1% by mass or less. However, when dehydrating from an organic solvent having a high water content, it is necessary to repeat the above-described steps. It is not effective for dehydration from organic solvents with a water content of about%.

  Under such circumstances, a separation method by pervaporation has attracted attention as a separation of water from an azeotropic water-containing organic solvent. In the pervaporation method, the mixed solution is flowed to the supply side of the separation membrane and separation functional material, and the permeation side is kept in a vacuum to evaporate only a specific component of the supply liquid through the separation membrane and the separation functional material to the permeation side. This is a method for separating and concentrating mixed components at the molecular level.

  Examples of separation functional materials used for pervaporation include an ion exchange membrane in which ion exchange groups are introduced into a porous polyethylene membrane in Patent Document 1, and a cross-linking reaction product of PVA and polystyrene sulfonic acid in Patent Document 2. Separation membrane comprising, an aromatic polyamide copolymer in Patent Document 3, and a separation composed of starch and a synthetic thermoplastic polymer containing cellulose acetate, cellulose nitrate, regenerated cellulose, alkylcellulose, and carboxymethylcellulose in Patent Document 4 Membrane, Patent Document 5 has a film having a thin film layer made of polyvinyl alcohol on a microporous film made of aromatic polyimide, aromatic polyamideimide or a mixture thereof, Patent Document 6 has a cellulose ester mixed film, Patent Document 7 Has proposed organic synthetic membranes such as carboxymethylcellulose membrane, These are film thickness, for example less in film thickness is small because the intensity is weak 100 [mu] m, film was a risk of damage when the separation process.

  Patent Document 8 discloses a zeolite membrane, Patent Document 9 discloses a porous support composed of 60 to 95 parts by mass of zeolite fine particles having an average particle size of 0.5 to 5 μm, and 5 to 40 parts by mass of an organic polymer or an organic polymer mixture. An inorganic synthetic film such as a body has been proposed. However, since these use an expensive inorganic porous support that requires firing at a high temperature, such as alumina and mullite, they are very expensive as a functional separation material, and the seed crystal is rubbed against the support. Although a zeolite membrane can be obtained by thermal synthesis, there has been a problem that the membrane has defects and poor separation due to non-crystalline components. Further, since it is basically inorganic, it has poor post-processability of the film, and if it is processed forcibly, there are problems such as generation of cracks and breakage of materials.

  In addition, the above-described organic synthetic membrane and inorganic synthetic membrane separation functional materials basically have a problem of high environmental burden and high cost when manufactured. In organic synthetic membranes, separation functional materials for cellulose derivatives existed in the past as described in Patent Documents 4, 6, and 7, but separation functional materials composed of fiber materials, especially cheap and environmentally friendly like paper. Until now, there has been no separation functional material for pervaporation using cellulosic fibers themselves with low post-processability.

  On the other hand, there is a material conventionally called vulcanized fiber. This is a tough organic industrial material made of natural fiber material made from wood pulp and cotton. It has excellent mechanical strength such as impact resistance and wear resistance, and has workability such as punching, bending and press molding. It is good. Furthermore, it is also a material excellent in oil resistance and electrical insulation. With this excellent mechanical strength, electrical insulation, and post-processing suitability, conventional lighting, TV, audio, spacers, washers, motor core ends, slot wedges, spacers, circuit breaker arc extinguishing plates, fuse cylinders, and electronic components Containers / partition plates, dry cell peripheral parts, electrical equipment parts for electrical insulation bonded to Nomex and PET film, or abrasive disks and abrasive belts that make use of impact resistance, wear resistance, heat resistance, and resin adhesion Various packing as a base material, machine parts, or base material for decorative board, building material as plywood surface material, or impact resistance, durability, non-impact, etc. by impact resistance, resin processability, printability, aging resistance, etc. Industrial safety equipment such as welding masks, welding holders, helmets, or impact resistance, abrasion resistance, aging resistance, depending on meltability, electrical insulation, drawability, etc. For large transport boxes, delivery boxes, suitcases, paperbacks, trays, tape cases, musical instrument cases, waste paper collection boxes, bag cores, shoe cores, various tags, armor equipment, cosmetics boxes, bowling alleys Various containers and miscellaneous goods as various structural members, or the materials and paper clips of school crafts, taking advantage of the warm taste and processability of natural materials, teaching materials, stationery and clothes as environment-friendly fiber hooks, easy-to-separate wraps Applications include food packaging materials as cutting edges for film and aluminum foil. Since this material is composed of natural cellulose fibers, it also has biodegradability when discarded and is suitable for clean incineration, and is an environmentally friendly industrial material.

For this vulcanized fiber, in order to proceed with the zinc chloride treatment in the process of manufacturing the vulcanized fiber proposed by the applicant in the past, a single-stage or multi-stage vibrating blade is fixed to the vibration shaft that vibrates in the axial direction. The present applicant proposes a method of manufacturing a device (10) having a vibration frequency of 10 to 60 Hz and a vibration width of 2 to 30 mm applied to the cleaning liquid in the dechlorination zinc tank. Vulcanized fiber (patent document 11), cotton and wood, and other cellulose pulps 50 to 90 wt% obtained by swelling and gluing each of the plurality of fiber base papers with a mixed solution of N-methylmorpholine-N-oxide and a polar solvent. And vulcanized dough with low density and excellent dimensional stability using base paper composed of 10 to 50 wt% of heat-fusible fiber Iba (Patent Document 12) but the like, all are those with conventional mechanical strength properties, electrical insulating properties, the scope of the post-processing suitability, was only one use application also utilizing these properties.
JP-A-61-161109 Japanese Unexamined Patent Publication No. 63-54903 Japanese Patent Laid-Open No. 01-299606 JP 05-123550 A Japanese Patent Laid-Open No. 05-168879 Japanese Patent Laid-Open No. 06-277473 Japanese Unexamined Patent Publication No. 07-51554 JP 2008-31072 A JP 2008-43864 A Japanese Patent Laid-Open No. 9-302594 Japanese Patent Laid-Open No. 11-247088 JP 2006-200044 A

  An object of the present invention is to provide a fiber sheet which is a separation functional material for pervaporation using a fiber material, in particular, cellulose fiber which is inexpensive and has a low environmental load.

This subject has a liquid-liquid separation function characterized in that one or more base papers whose main fibers are composed of natural cellulose fibers are immersed, swelled, dissolved, and glued in an aqueous zinc chloride solution. It has been solved by a fiber sheet for the pervaporation method having a single layer or a laminate.

  By the fiber sheet of the present invention, it is possible to provide a separation functional material for pervaporation that is inexpensive, has low environmental impact, has high strength, and is easily post-processed.

  Next, the present invention will be described in detail.

  The fiber sheet having a separation function of the present invention is obtained by swelling, dissolving, and gluing a base paper whose main fiber is composed of natural cellulose fibers, and is conventionally also called a vulcanized fiber.

  As a result of earnest examination of the characteristics of this fiber sheet, also called vulcanized fiber, the present inventors have found that the mechanical strength characteristics, the electrical insulation characteristics, the post-processing suitability, and the liquid-liquid separation functional characteristics that were not previously known, The present inventors have newly found that there is a functional property of separating a liquid mixture with high selectivity by a pervaporation method, and newly provided an application for use in liquid-liquid separation of a liquid mixture.

The fiber sheet of the present invention is swelled, dissolved, and gelatinized by immersing a base paper whose main fiber is composed of natural cellulose fibers in an aqueous zinc chloride solution . As one of the methods, for example, one or two or more base papers are immersed in a concentrated aqueous solution of zinc chloride to swell, dissolve, and gelatinize the base paper, and those in the case of using two or more base papers. And a step of drying and finishing through a step of dezincification in which zinc chloride is removed with a washing liquid to stop the dissolution reaction. As another method, instead of zinc chloride aqueous solution, N-methylmorpholine-N-oxide, a mixed solution of N-methylmorpholine-N-oxide and polar liquid, sulfuric acid or the like is used to swell the base paper, A method of producing by dissolution and gelatinization is also included. In addition to the aqueous zinc chloride solution, the fiber sheet of the present invention can be obtained as long as it is a chemical solution that swells, dissolves, and gelatinizes cellulose fibers, but at the industrialization level, the method using an aqueous zinc chloride solution is the most industrialized and mass production. This is the most desirable.

  In addition, when the fiber sheet of this invention obtains a thing with thick paper thickness, after laminating | stacking several sheets of base paper, it is dechlorinated, then dried and finished. On the other hand, when a thin product is obtained, the laminating process is not required with only one base paper. Various fiber sheet thicknesses are possible for the required properties.

  Examples of the drying method include hot air drying, microwave drying, infrared drying, and roll dryer drying. The drying temperature is preferably 70 ° C to 140 ° C. More preferably, the temperature is from 80 ° C to 120 ° C. If it is less than 70 ° C., the water in the fiber sheet cannot be completely dried and remains on the sheet, resulting in poor drying. When the temperature exceeds 140 ° C., particularly when the sheets are laminated, there is a problem that air accumulates and swells between the sheet layers due to rapid drying.

The base paper used for the production of the fiber sheet of the present invention is made of cotton fibers such as cotton broken cloth (cotton rag) pulp and linter, cellulose fibers such as wood fiber pulp, kenaf pulp, bamboo pulp and rayon. It is manufactured by wet papermaking. The properties required for the base paper are required to have proper water absorption, air permeability and uniform texture so that it can penetrate and react uniformly when immersed in an aqueous zinc chloride solution . Moreover, when addition of another function is calculated | required, the compounding of an organic compound fiber and an inorganic fiber is also possible within the range which does not impair the functional characteristic of this invention.

  When using the fiber sheet of the present invention installed in a pervaporation liquid-liquid separation device, it is used after being processed into modules of various shapes such as spiral and pleated as well as single-sheet. Is possible.

  Using the fiber sheet of the present invention, it is possible to separate at least one liquid from a mixed solution of two or more liquids by a pervaporation method. As the mixed solution, a mixed solution of water and an organic material and a mixed solution of two or more organic materials are preferably used. In particular, it is suitably used for a mixed solution of water and alcohol that requires azeotropic distillation during distillation separation.

  When using the fiber sheet of the present invention, it is preferable to perform pervaporation separation of the mixed solution in a state in which water at room temperature is previously applied to the fiber sheet. More preferably, the moisture content of the fiber sheet is 90% by mass or more. In the case of a fiber sheet having no moisture or a moisture content of less than 90% by mass, the initial permeation of separated water may not be performed well.

  In the case of selectively separating water from a mixed solution containing water and organic matter by a pervaporation method, for example, in order to selectively separate ethanol or water from a mixed solution containing ethanol and water obtained by fermentation, conventionally, Distillation was a common separation method. However, since a mixture of ethanol and water obtained by fermentation contains a large amount of water, a large amount of energy is required for separation and concentration by distillation. In such a case, when the fiber sheet of the present invention is used, it is possible to selectively separate only the target product from the mixture of water and organic matter by using a pervaporation method and using less energy. In this case, water is selectively separated on the permeate side, and only organic substances remain on the supply liquid side.

  As shown in the photograph of FIG. 1, the electron micrograph of the fiber sheet of the present invention shows that the cellulose fibers are dissolved and fixed to each other, and the sheet gap is very small. On the other hand, in the fiber sheet base paper before swelling, dissolution, and gelatinization shown in the photograph of FIG. 2, the cellulose fibers are intertwined but are not dissolved and fixed, and the voids are large. Ordinary paper has a large gap like this base paper, so if you try to use it for liquid-liquid separation in the pervaporation method, the supply mixture easily passes through the gap in the paper and the separation effect is completely obtained. Absent. Since the fiber sheet of the present invention is in a state where the fibers are dissolved and fixed to each other and the voids are very small, it is in a pseudo state close to a cellulose film, and has a very high chemical compatibility with cellulose. Only water in the high feed mixture can pass to the permeate side. However, unlike the conventional separation membrane material, the fiber sheet of the present invention, as can be seen from FIG. 1, has good water permeability due to the presence of microscopic fine voids. The separation membrane material can be made sufficiently thicker, the sheet strength during pervaporation can be increased, and there is no need for a separate support for use. Since the filtration surface area is increased by the microscopic fine voids, the separation efficiency can be further increased. And it is a separation material that is much cheaper and less environmental impact than before.

[Example]
EXAMPLES Next, although this invention is demonstrated based on an Example, this invention is not limited to these Examples.

(Creation of fiber sheet base paper)
As a cellulose pulp raw material, tap water is added to 70% by weight of softwood pulp and 30% by weight of hardwood pulp to obtain a pulp solids concentration of 2% by weight. After beating to Canadian freeness 500ml with a test beater, Wet paper was obtained by diluting to a concentration of 0.3% by weight and making paper using a hand-making machine. Excess moisture from the wet paper is dried with a metal plate plate on one side of the wet paper to perform tension dehydration by press dewatering for 5 minutes using a hand-drawing press with a gauge pressure of 4 kg / cm ² . This was set in a frame and dried in a circulating dryer at 120 ° C. for 1 hour. The base paper after drying had a basis weight of 90 g / m ² and a thickness of 0.16 mm.

(Creation of fiber sheet by swelling, dissolution and gelatinization of base paper)
A concentrated aqueous solution of zinc chloride (liquid concentration: 70 ° Baume, liquid temperature: 46 ° C.) was used as the swelling glue solution. Each of the three base papers was immersed in the same solution to swell, dissolve and glue the surface of the base paper, and after wiping off these three excess swelling gelling solutions, pressure lamination was performed at 70 ° C. 15 After ripening and immersing in water at 5 ° C to remove the solution for swelling gelatinization, after wiping off the excess water of this laminate, it is dried with a table roll dryer with a surface temperature of 110 ° C, A fiber sheet having a thickness of 0.25 mm and a density of 1.1 g / cm ³ was obtained.

(Evaluation of liquid-liquid separation characteristics by bar vaporization)
A device as shown in FIG. 3 was prepared, and the pervaporation behavior of the fiber sheet of Example 1 was examined. As shown in FIG. 3, a filter cell, a trap, and a pump were connected by a stainless steel pipe having an outer diameter of 1 inch, and a line was prepared so that the inside of the pipe could be exhausted by the pump. Then, the fiber sheet produced as described above was cut into a circle having a diameter of 4.5 cm and attached to a filter cell, and a solution of ethanol (ethyl alcohol) / water = volume ratio 2/1 was pumped with a pressure difference of 1. The operation was performed at 33 × 10 ⁴ Pa (100 Torr), and pervaporation was performed for 1 hour. The pressure was measured with a Baratron 122AA, and the permeated solution was collected in a trap at liquid nitrogen temperature and permeated with a gas chromatograph (Shimadzu GC-14B, TCD detector, Sunpak A50 / 80 Thermon-1000, 150 ° C). Analysis of the ethanol / water inside was performed. FIG. 4 shows a gas chromatographic analysis chart when ethanol / water = 2/1. Before and after permeation of the fiber sheet, the ethanol peak is extremely small, and it can be seen that the fiber sheet produced as described above is selectively separated. When each component of the gas chromatograph before permeation is x, after permeation is y, w is water, and e is ethanol, the separation efficiency α _{e / w} = (x _w / x _e ) / (y _w / y _e ) = 2.45, indicating that the alcohol concentration in the filter cell was increased.

It is an electron micrograph of the fiber sheet of the present invention. It is an electron micrograph of the fiber sheet base paper before swelling, dissolution, and gelatinization. It is the schematic of the apparatus for evaluation of a liquid-liquid separation characteristic. It is a gas chromatographic analysis chart of the liquid before permeation and the separated liquid after permeation when ethanol / water = 2/1.

Claims (1)

A monolayer having a liquid-liquid separation function, characterized in that one or more base papers whose main fibers are composed of natural cellulose fibers are immersed in an aqueous zinc chloride solution to swell, dissolve and gelatinize Fiber sheet for laminated pervaporation process.