Sheet for heat exchange
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Solution Overview
Problem
Existing heat exchange element sheets face issues with low shape stability and water resistance due to the dissolution of inorganic salts in condensation water, leading to decreased moisture permeability and gas shielding properties, especially in environments with condensation or icing.
Innovation Solution
A laminate sheet for heat exchange elements comprising a porous base material and a resin layer containing polyvinylpyrrolidone and/or vinylpyrrolidone copolymer, along with a urethane resin, where the resin layer has a crosslinked structure and a specific mass content ratio, enhancing water resistance and shape stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating liquid for hydrophilic resin film formation is applied on a porous base material and irradiated with ultraviolet rays to crosslink the polyvinylpyrrolidone component, then water resistance is improved, but shape stability deteriorates due to curing and shrinking of the hydrophilic resin film
Solution Approach 1:
The patent changes the crosslinking parameters by using a specific crosslinking agent (glycidyl methacrylate) and controlling the crosslinking degree to achieve a balance between water resistance and shape stability. The crosslinking is performed under controlled conditions to minimize shrinkage while maintaining the hydrophilic properties and water resistance of the resin film.
Solution Approach 2:
The patent creates a composite resin film structure by combining polyvinylpyrrolidone with a crosslinking agent (glycidyl methacrylate) to form a crosslinked network. This composite structure provides both the water resistance needed for heat exchange performance and improved dimensional stability compared to non-crosslinked polyvinylpyrrolidone alone.
2Quantity of substance
If inorganic salt is used as hygroscopic agent in paper sheet, then moisture permeability is improved, but gas shielding property deteriorates due to dissolution in condensation water
Solution Approach 1:
The patent replaces the non-renewable inorganic salt with an organic polymer (polyvinylpyrrolidone) that can maintain its hygroscopic function over time without dissolving. The polymer acts as a long-lasting hygroscopic agent that preserves both moisture permeability and gas shielding properties throughout the service life of the heat exchange element.
Solution Approach 2:
The patent changes the type of hygroscopic material from inorganic salt to organic polymer, fundamentally altering the chemical properties. The polymer provides continuous moisture absorption capability without the dissolution problem, maintaining stable gas shielding properties while ensuring sustained moisture permeability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a sheet with high water resistance and shape stability, maintaining moisture permeability and gas shielding properties over time, even in humid environments, thereby improving the productivity of heat exchange elements.
Implementation Method 1
the resin layer containing at least polyvinylpyrrolidone and/or vinylpyrrolidone copolymer
Implementation Method 2
the resin layer has a crosslinked structure... the polyvinylpyrrolidone component of the hydrophilic resin film is crosslinked, whereby the polyvinylpyrrolidone component of the hydrophilic resin film is prevented from dissolving into condensation water
Data Source
AI summary
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.