Sheet for heat exchange
The present invention addresses the problem of providing a sheet for heat exchange elements, which has high water resistance, while also having excellent productivity by achieving excellent shape stability. The present invention is a sheet for heat exchange elements, which is provided with a laminate that is composed of at least a porous substrate and a resin layer, and which is configured such that the resin layer contains at least a urethane resin and a polyvinylpyrrolidone and/or a vinylpyrrolidone copolymer.
1. A sheet for heat exchange elements comprising at least a laminate of a porous base material and a resin layer,
the resin layer containing at least polyvinylpyrrolidone and/or a vinylpyrrolidone copolymer and a urethane resin,
wherein the resin layer contains an acrylic resin and
a content of the acrylic resin is 2 mass % or more and 13 mass % or less relative to 100 mass % of the entire resin layer,
wherein a content of the polyvinylpyrrolidone and/or vinylpyrrolidone copolymer is 50% by mass or more and 95% by mass or less relative to 100% by mass of the entire resin layer, and wherein a content ratio between the polyvinylpyrrolidone and/or vinylpyrrolidone copolymer, and the urethane resin (content (mass %) of the polyvinylpyrrolidone and/or vinylpyrrolidone copolymer/content (mass %) of the urethane resin) is 1.0 or more and 9.0 or less,
wherein the acrylic resin has a crosslinked structure comprising a structure as represented by either chemical formula (I) or (II) given below:
wherein R 1 and R 2 are each an alkyl chain having a length in the range of C1 and C5 and X 1 to X 6 are each an appropriate atom or molecular structure, and
wherein R 1 to R 4 are each an alkyl chain having a length in the range of C1 and C5 and X 1 to X 8 are each an appropriate atom or molecular structure.
2. A sheet for heat exchange elements as set forth in claim 1 , wherein the content of the polyvinylpyrrolidone and/or vinylpyrrolidone copolymer is 50% by mass or more and 85% by mass or less relative to 100% by mass of the entire resin layer, and wherein the content ratio between the polyvinylpyrrolidone and/or vinylpyrrolidone copolymer and the urethane resin (content (mass %) of the polyvinylpyrrolidone and/or vinylpyrrolidone copolymer/content (mass %) of the urethane resin) is 2.0 or more and 6.0 or less.
3. A sheet for heat exchange elements as set forth in claim 1 , wherein the polyvinylpyrrolidone and/or vinylpyrrolidone copolymer has a crosslinked structure.
4. A sheet for heat exchange elements as set forth in claim 1 , wherein a basis weight of the resin layer is 0.1 g/ m 2 or more and a ratio of the basis weight of the resin layer to the basis weight of the porous base material (basis weight of the resin layer/basis weight of the porous base material) is 0.18 or less.
5. A heat exchange element comprising the sheet for heat exchange elements as set forth in claim 1 .
6. A heat exchanger comprising the heat exchange element as set for in claim 5 .
7. A method for producing a sheet for heat exchange elements as set forth in claim 1 comprising the step in which a coating liquid composition containing a polyvinylpyrrolidone and/or vinylpyrrolidone copolymer, a urethane resin, and an acrylic resin having a structure in which acrylate chains have two or more cross-linkable carbon-carbon double bonds is applied on the porous base material to form a coating film, followed by exposing the coating film to ultraviolet ray.