JPH0373798B2 - - Google Patents

Description

[Detailed description of the invention]

B. Field of Industrial Application of the Invention The present invention relates to a total heat exchanger. Recently, heat exchangers have come to be used as ventilation systems for houses and buildings, and in particular, total heat exchangers, which perform not only sensible heat exchange but also latent heat exchange at the same time, are becoming popular as extremely useful devices. This total heat exchange is achieved by partitioning the two types of air streams to be heat exchanged by an element having thermal conductivity and moisture permeability. The present invention relates to this total heat exchange element. Conventional technology As a conventional total heat exchange element, for example, the
−6382, in which a fibrous base material is impregnated with a hygroscopic organic polymer resin, Special Publication No. 52-
Those using a hydrophilic organic polymer film alone, such as No. 10214, those using Japanese paper or asbestos paper or unglazed ceramic impregnated with high boiling point polyhydric alcohol, etc., as shown in Japanese Patent Publication No. 51-42334.
A hollow membrane of regenerated cellulose impregnated with polyhydric alcohol as in JP-A No. 54-37955;
54-136570, in which a porous material is impregnated with a solution of a hydrophilic polymer containing additives, the additives are removed, pores are formed, and a hygroscopic substance is attached to the porous material. . Problems to be Solved by the Invention Among these conventional techniques, for example, those using hydrophilic polymers have a major drawback that they have poor water-resistant adhesion, and the parts where the elements are bonded contain water and are easily peeled off. Products using this hydrophilic polymer have a problem in that their moisture permeability is significantly reduced at low humidity. Similarly, those using polyhydric alcohol also have the disadvantage of weak adhesiveness when moisture is absorbed. In addition, none of these conventional technologies can be said to have satisfactory total heat exchange properties, and it is desirable to further improve the most important physical properties of this element, namely gas barrier properties (air impermeability) and moisture permeability. it is conceivable that. The present invention aims to provide a total heat exchange element that has improved water-resistant adhesion, excellent moisture permeability and gas barrier properties, and can therefore improve total heat exchange performance. B. Structure of the Invention The structure of the present invention consists of an esterified cellulose, which has greater hydrophilicity and flexibility than the esterified cellulose, has film-forming ability by itself, and is compatible with the esterified cellulose. The gist of the present invention is a total heat exchange element characterized by having, as an essential component, a moisture permeable film containing an organic polymer substance. Measures to solve the problem First, we focused on the high moisture permeability of esterified cellulose, and conducted research using it alone or with various plasticizers. After learning that the agent had the disadvantage of large changes over time as it migrated or eluted over time, and after further considering the combination of various substances, the patent application filed at the same time as the present invention (Japanese Patent Application Laid-Open No.
259896), we have succeeded in finding an organic substance that meets specific conditions, maintaining the moisture permeability of esterified cellulose, improving film forming properties, and improving water-resistant adhesion. At the same time, organic polymers that do not act as plasticizers but can be blended with esterified cellulose as a suitable blend material to improve total heat exchangeability and water-resistant adhesion can also be used in addition to organic substances under these specific conditions. They succeeded in selecting a substance. This organic polymer substance is compatible with esterified cellulose, has greater hydrophilicity and flexibility than esterified cellulose, and has film-forming ability by itself. In the present invention, esterified cellulose includes, for example, cellulose acetate as the most common one, and examples of the organic polymer substances include, for example, low acetate cellulose acetate, low saponification degree polyvinyl alcohol, partially esterified polyacrylic Examples include acids. Low-acetyl cellulose acetate is more hydrophilic and flexible than the base cellulose acetate with a high degree of acetate, has film-forming ability by itself, and is naturally compatible with the base cellulose acetate. . Similarly to the above, low saponification degree polyvinyl alcohol has greater hydrophilicity and flexibility than cellulose acetate, has film-forming ability by itself, and is compatible with cellulose acetate. Note that polyvinyl alcohol with a high degree of saponification has poor compatibility with cellulose acetate and cannot be used for the purpose of the present invention. Similarly, partially esterified polyacrylic acid is also used in the above 2.
Like other types of polymeric substances, it has the above-mentioned physical properties necessary for the present invention. If the hydrophilicity of these polymeric substances is lower than that of esterified cellulose, the moisture permeability will decrease, and if the flexibility of these polymeric substances is lower than that of esterified cellulose, it may not be possible to compensate for the brittleness of esterified cellulose. Furthermore, if these polymeric substances do not have film-forming ability, when blended with esterified cellulose, this blend also has a low film-forming ability and gas barrier properties. Note that it is a matter of course that these polymeric substances must be compatible in order to be blended into the esterified cellulose. In addition, these polymeric substances in the present invention are the above-mentioned 3
It goes without saying that the material is not limited to these types of materials, and may be any other organic polymer material that satisfies the above conditions. The device of the present invention is prepared by mixing and blending the above-mentioned organic polymeric substance and esterified cellulose in a suitable solvent, and coating and drying the mixture to form a moisture-permeable film. The device of the present invention may use this film alone, but in most cases, this film is formed by processing a porous sheet such as a base paper to form an integral film. It is used for The blending ratio of the esterified cellulose and the above-mentioned organic polymeric substance is not particularly limited, but it is usually preferable to mix 90 to 50 parts by weight of the former to 10 to 50 parts by weight of the latter. Function: In the device of the present invention, the esterified cellulose is softened by the polymer substance to cover its brittleness, and the hydrophilicity of the polymer substance improves moisture permeability and film forming properties. Therefore, it has excellent gas barrier properties, thus improving total heat exchange properties, and also has good water-resistant adhesive properties due to the polymeric substance. Example 1 70 parts by weight of cellulose acetate with a degree of acetylation of 55% and a degree of polymerization of 150 and 30 parts by weight of cellulose acetate with a degree of acetylation of 45% and a degree of polymerization of 110 as a blended polymer substance in acetone.
The mixture was blended in a mixed solvent of 90% methanol and 10% methanol, coated on a base paper to a solid content of 5 g/m ² , air-dried and heat-treated at 80° C. for 5 minutes to prepare a test piece. Example 2 70 parts by weight of the same cellulose acetate as in Example 1 and 30 parts by weight of polyvinyl alcohol with a degree of saponification of 40% as a blended polymer substance were coated on the base paper in the same amount as in Example 1. A test piece was heat-treated in the same manner. Comparative Example 1 Acetylation degree instead of the blended polymer material of Example 1
Cellulose acetate with a polymerization degree of 61% and 360 was used, methylene chloride was used as the solvent, and all other conditions were the same as in Example 1, and the base paper was coated to the same amount and heat treated in the same manner. And so. Comparative Example 2 Using polyethylene glycol as a hydrophilic plasticizer instead of the blended polymer material of Example 1,
A test piece was obtained under the same conditions as in Example 1 except for the following conditions. Blank Test 1 Only the base paper used in Example 1 was used as a test piece. Blank test 2 The base paper used in Example 1 was coated with a solution of only the base cellulose acetate from Example 1 to a solid content of 5 g/m ² and heat treated in the same manner to obtain a test piece. . For each of the above test specimens, we manufactured a total heat exchanger that exchanged total heat through the bellows-type partition surface, and
A two-way total heat exchange between outside air at RH 62% and 32℃ and indoor air at RH 40% and 25℃ is performed to improve humidity exchange efficiency, that is, latent heat exchange efficiency, carbon dioxide transfer rate (gas transferability), water resistance adhesion, and curl. When the phenomena were measured, the results shown in the following table were obtained.

[Table] Note that in terms of water-resistant adhesion, the mark ○ indicates that the test piece was laminated with ethylene vinyl acetate resin and did not peel off after being immersed in water for 5 minutes. In addition, regarding the curl phenomenon, those with large changes over time are marked with an "x", those with a slight change are marked with a △, and those with almost no change are marked with an ○. From this table, it can be seen that Examples 1 and 2 have excellent latent heat exchange properties, that is, moisture permeability, and also have good gas barrier properties and high water-resistant adhesion, while Comparative Example 1 cannot overcome the brittleness of the base cellulose acetate. Therefore, like Blank Test 2, this test has the disadvantage that the curling phenomenon is significant. Furthermore, Comparative Example 2 had poor gas barrier properties and water-resistant adhesive properties, and Blank Test 1 had very low gas barrier properties. Furthermore, Examples 1 and 2 overcome the fragility, which is a drawback of cellulose acetate, and improve film-forming properties. C. Effects of the Invention As explained in detail above, the total heat exchange element of the present invention improves the moisture permeability of esterified cellulose by blending the esterified cellulose with a polymeric substance having high flexibility and hydrophilicity. At the same time, it overcomes its brittleness, improves its film formation properties, and improves its gas barrier properties, making it extremely useful as a total heat exchange element.Moreover, it has excellent water-resistant adhesion properties, making it suitable for adhesion between elements. This has the excellent effect of preventing the parts from peeling off when they absorb moisture.

Claims (1)

[Scope of Claims] 1. Esterified cellulose, and an organic polymer that has greater hydrophilicity and flexibility than the esterified cellulose, has film-forming ability by itself, and is compatible with the esterified cellulose. A total heat exchange element characterized in that an essential component is a moisture permeable film containing a substance. 2. The total heat exchange element according to claim 1, wherein a moisture permeable film, which is an essential component, is treated on the porous sheet.