Fine cellulose fiber sheet

Abstract

The present invention provides a fine cellulose fiber sheet, of which various properties and functions such as paper making ability, solvent resistance, adhesion, functionalization agent immobilization, surface zeta potential, hydrophilicity, hydrophobicity, and air permeation resistance are finely controlled, through a process having low environmental impact. A fine cellulose fiber sheet according to the present invention fulfills all of the following requirements (1) to (3): (1) comprises fine cellulose fibers having an average fiber diameter of 2 nm or greater and 1000 nm or less; (2) the weight ratio of the fine cellulose fibers is 50 wt % or greater and 99 wt % or less; and (3) the block polyisocyanate aggregate content as a weight ratio is 1 to 100 wt % of the weight of the fine cellulose fibers.

1 - 28 . (canceled) 
     
     
         29 . A fine cellulose fiber sheet for a total heat exchanger sheet, wherein the fine cellulose fiber sheet fulfills all of the following requirements (1) to (3):
 (1) it comprises fine cellulose fibers having an average fiber diameter of 2 nm to 1000 nm and a blocked polyisosyanate aggregate;   (2) the weight ratio of the fine cellulose fibers is 50% by weight to 99% by weight; and,   (3) the weight ratio of a blocked polyisocyanate aggregate to the fine cellulose fibers is 1% by weight to 100% by weight.   
     
     
         30 . The fine cellulose fiber sheet for a total heat exchanger sheet according to  claim 29 , wherein a cationic group is introduced into the blocked polyisocyanate aggregate. 
     
     
         31 . The fine cellulose fiber sheet for a total heat exchanger sheet according to  claim 29 , wherein all or a portion of the blocked polyisocyanate aggregate is chemically bound to the fine cellulose fibers to form a crosslinked structure. 
     
     
         32 . A fine cellulose fiber sheet for a total heat exchanger sheet, wherein the fine cellulose fiber sheet fulfills all of the following requirements (1) to (4):
 (1) it comprises fine cellulose fibers having an average fiber diameter of 2 nm to 1000 nm and a blocked polyisosyanate aggregate;   (2) the weight ratio of the fine cellulose fibers is 50% by weight to 99% by weight;   (3) a blocked polyisocyanate is uniformly distributed in the sheet in the planar direction and thickness direction; and,   (4) the weight ratio of the blocked polyisocyanate to the fine cellulose fibers is 1% by weight to 100% by weight.   
     
     
         33 . The fine cellulose fiber sheet for a total heat exchanger sheet according to  claim 32 , wherein the blocked polyisocyanate is chemically bound to the fine cellulose fibers. 
     
     
         34 . The fine cellulose fiber sheet for a total heat exchanger sheet according to  claim 32  or  33 , wherein a cationic group is introduced in the blocked polyisocyanate. 
     
     
         35 . The fine cellulose fiber sheet for a total heat exchanger sheet according to  claim 32  or  33 , wherein the blocked polyisocyanate is a blocked polyisocyanate aggregate. 
     
     
         36 . The fine cellulose fiber sheet for a total heat exchanger sheet according to  claim 31  or  33 , wherein at least one type of functionalization agent selected from the group consisting of a water-repellent oil processing agent, water-soluble polymer, antimicrobial polymer, thermoplastic resin, thermosetting resin and photocurable resin is immobilized inside and/or on the surface of a fine cellulose fiber layer by the blocked polyisocyanate. 
     
     
         37 . A laminated structure for a total heat exchanger sheet in which the fine cellulose fiber sheet for a total heat exchanger sheet according to  claim 29  or  32  and a sheet composed of an organic polymer are laminated. 
     
     
         38 . The laminated structure for a total heat exchanger sheet according to  claim 37 , wherein the fine cellulose fiber sheet for a total heat exchanger sheet and the sheet composed of an organic polymer are chemically crosslinked by the blocked polyisocyanate. 
     
     
         39 . The laminated structure for a total heat exchanger sheet according to  claim 38 , wherein a hydrophilic compound is contained in the laminated structure at 1% by weight to 50% by weight as the weight ratio of the laminate. 
     
     
         40 . The laminated structure for a total heat exchanger sheet according to  claim 39 , wherein the hydrophilic compound contains at least one type of compound selected from inorganic salts consisting of lithium chloride, calcium chloride and magnesium chloride, carboxymethyl cellulose, carboxyethyl cellulose, hydroxyalkyl cellulose and salts or crosslinked products thereof, and organic compounds consisting of polyethylene glycol, polypropylene glycol and polyvinyl alcohol. 
     
     
         41 . An aqueous dispersion for coating or papermaking for a total heat exchanger sheet comprising fine cellulose fibers and a water-dispersible blocked polyisocyanate. 
     
     
         42 . The aqueous dispersion for coating or papermaking for a total heat exchanger sheet according to  claim 41 , wherein the water-dispersible blocked polyisocyanate is cationic. 
     
     
         43 . The aqueous dispersion for coating or papermaking for a total heat exchanger sheet according to  claim 41 , wherein the fiber diameter of the fine cellulose fibers is 2 nm to 1000 nm. 
     
     
         44 . The aqueous dispersion for coating or papermaking for a total heat exchanger sheet according to  claim 41 , containing at least one type of water-soluble or water-dispersible functionalization agent selected from the group consisting of a water-repellent oil processing agent, water-soluble polymer, antimicrobial polymer, thermoplastic resin, thermosetting resin and photocurable resin. 
     
     
         45 . A method for producing the fine cellulose fiber sheet for a total heat exchanger sheet according to  claim 29  or  32 , comprising the following steps:
 a preparation step for preparing the aqueous dispersion according to  claim 41 , 
 a papermaking step for dehydrating the aqueous dispersion by filtration and forming a moisture-containing sheet, and 
 a step for drying the moisture-containing sheet. 
 
     
     
         46 . A method for producing the fine cellulose fiber sheet for a total heat exchanger sheet according to  claim 31  or  33 , comprising the following steps:
 a preparation step for preparing the aqueous dispersion according to  claim 41 , 
 a papermaking step for dehydrating the aqueous dispersion by filtration and forming a moisture-containing sheet, 
 a step for drying the moisture-containing sheet, and 
 a heating step for heating the dried sheet. 
 
     
     
         47 . A method for producing the laminated structure for a total heat exchanger sheet according to  claim 37 , comprising the following steps:
 a preparation step for preparing the aqueous dispersion according to  claim 41 ,   a papermaking step for dehydrating the aqueous dispersion on a sheet composed of an organic polymer by filtration and forming a moisture-containing laminated structure in which a fine cellulose fiber layer is laminated on a sheet composed of the organic polymer, and   a step for drying the moisture-containing laminated structure.   
     
     
         48 . A method for producing the laminated structure for a total heat exchanger sheet according to  claim 38 , comprising the following steps:
 a preparation step for preparing the aqueous dispersion according to  claim 41 ,   a papermaking step for dehydrating the aqueous dispersion on a sheet composed of an organic polymer by filtration and forming a moisture-containing laminated structure in which a fine cellulose fiber layer is laminated on a sheet composed of the organic polymer,   a step for drying the moisture-containing laminated structure, and   a heating step for heating the dried laminated structure.   
     
     
         49 . A total heat exchanger sheet comprising the fine cellulose fiber sheet for a total heat exchanger sheet according to  claim 29  or  32 . 
     
     
         50 . The total heat exchanger sheet according to  claim 49 , wherein the average thickness of the laminated structure is 10 μm to 100 μm. 
     
     
         51 . A total heat exchange element in which the total heat exchanger sheet according to  claim 49  is used as a partition that divides two types of air flow having different temperature, different humidity or both. 
     
     
         52 . A total heat exchanger that uses the total heat exchange element according to  claim 51 .