JPS5846325B2 - Method for manufacturing a moisture-permeable gas shield - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a moisture-permeable gas shield used in a total heat exchanger of an air conditioning (hereinafter referred to as air conditioning) equipment.

In recent years, as air-conditioning equipment such as heating or cooling equipment has developed and become more widespread, and the living areas using these equipment have expanded, there has been an increasing demand for air-conditioning heat exchangers that can recover temperature and humidity for ventilation. There is.

The characteristics of the moisture permeable gas shield that is the material of such an air conditioning heat exchanger are required to have low air permeability and high moisture permeability.

This prevents the fresh air that is drawn into the room from the outdoors and the dirty air that is discharged from the room to the outdoors during use, and also exchanges both sensible heat and latent heat (heat of vaporization of water vapor). This is because, in order to achieve this, it is required that water vapor is efficiently transferred between intake air and exhaust air.

In order to meet such demands, the inventors of the present invention several years ago developed a water-soluble polymer material containing lithium rhodanide as a moisture absorbent, such as paper, cloth, non-woven fabric, etc.
By impregnating or coating a porous material such as asbestos paper or ceramic thin plate, it has low air permeability.
Moreover, he invented a gas shield with improved moisture permeability (Japanese Patent Publication No. 52-1.5071).

The air permeability coefficient (quantitative value of air permeability) and moisture permeability coefficient (quantitative value of moisture permeability) of this moisture-permeable gas shield depend on the content of the moisture absorbent and water-soluble polymer substance, and the air permeability coefficient mainly depends on the content of the moisture absorbent and water-soluble polymer substance. The moisture permeability coefficient decreases as the content of the water-soluble polymer substance increases, and the moisture permeability coefficient mainly increases as the content of the moisture absorbent increases.

However, the air permeability coefficient and the moisture permeability coefficient of a moisture-permeable gas shield do not change independently; if the content of water-soluble polymeric substances is increased in order to reduce the air permeability coefficient, the moisture permeability coefficient also decreases. In order to improve moisture permeability, it is not enough to increase the content of moisture absorbers, but it is also necessary to decrease the content of water-soluble polymer substances at the same time. As a method to satisfy both the air permeability coefficient and the moisture permeability coefficient, which have a relationship between , previously filed a patent application for a moisture-permeable gas shield with a dense hygroscopic thin layer formed on the surface layer of a porous member.

After that, as a result of repeated trial production on an industrial scale of a moisture-permeable gas shield having the above-mentioned drug content distribution, the following three results were discovered.
It has been found that a moisture-permeable gas shield that satisfies a high degree of gas selective permeability cannot be obtained unless all of the following conditions are satisfied.

(1) Using a base paper with an optimal size degree; (1)
1) Use a processing method that does not destroy the drug content distribution; (11:) Keep the drug content within an optimal range;
Then, industrial paper of different sizes is used as a porous member, and it is impregnated with a water-soluble polymeric substance containing a moisture absorbent.
As a result of repeated studies on the air permeability and moisture permeability coefficients of the moisture-permeable gas shield obtained by treatment using either the coating method or the coating method, we found that a weakly water-resistant porous member with a size degree of 20 to 200 seconds was obtained. The porous member is impregnated, applied, or coated with an aqueous solution of a polymeric substance containing a moisture absorbent, and dried before the aqueous solution penetrates into the porous member to fix the drug content distribution. The inventors have discovered that it is possible to produce a moisture-permeable gas shield that satisfies the selective permselectivity of the present invention, and have completed the present invention.

In this invention, as the porous member, paper such as non-hydrophobic Japanese paper, sashimi paper, western paper, cloth such as gauze, cotton cloth, non-woven fabric, or thin ceramic plate is used, but paper is preferable. It is.

A natural sizing agent such as rosin or glue or a synthetic sizing agent such as polymeron or pearl gum is added to the porous member from 1 to 10%.
By adding it in advance or impregnating it later in a range of % by weight, the sizing degree is set to 20 to 200 seconds according to the sizing degree test method according to JIS Standard P8], 22-54.

If this size degree is less than 20 seconds, an aqueous solution of a water-soluble polymeric substance containing a hygroscopic agent will penetrate into the porous part relatively quickly, making it difficult to form a drug content distribution. It becomes difficult to produce base paper with a good reproducibility.

A size degree of 200 seconds or more is not suitable because it becomes difficult to contain the drug and the optimum content rate cannot be met.

In addition, it is preferable that the size degree is in the range of 40 to 150 seconds.

As the moisture absorbent, halides, oxides, salts, and hydroxides, which are generally used as drying agents, as well as hygroscopic substances or polyhydric alcohols can be used, and lithium halides are particularly preferred. do.

As the water-soluble polymer substance, commonly used water-soluble polymer resins, natural resins, or mixtures thereof, such as polyvinyl alcohol resins, polyvinyl methyl ether resins, polyacrylic acid resins, polymethacrylic resins, and methyl cellulose, are used.

Note that polyvinyl alcohol or hydroxyethyl cellulose is preferred.

Furthermore, when forming a dense thin layer of the polymeric material containing the moisture absorbent in the weakly water-dispersible porous member, the moisture absorbent is added to the porous member at a content of 10 to 50% by weight. It is preferable to impregnate, coat or coat with a polymeric substance containing the material.

If the content is less than 10% by weight, the breathability becomes too high, and if it is more than 50% by weight, not only is the moisture permeability poor, but the resulting moisture-permeable gas shield absorbs moisture and becomes sticky.
This is not preferable because it generates drain.

The dense thin layer of polymeric material containing the hygroscopic agent is
It is formed by preparing an aqueous solution of ~5% by weight and 5~20% by weight of a polymeric substance, and using this aqueous solution to impregnate, apply, or coat the weakly wetted porous member.

At this time, in the impregnation method, if the squeezing pressure is too high, the chemical solution will be forced into the base paper, which is a porous member, and the content distribution will be destroyed.

Incidentally, a flame retardant or the like may be added to the aqueous solution as necessary.

The moisture-permeable gas shield obtained by the method of the present invention as described above is formed as a dense hygroscopic thin layer on the surface layer of a weakly wrenable porous member whose base is a polymeric material containing a hygroscopic agent. For example, gases such as air and carbon dioxide are blocked by a dense thin layer and are almost impossible to pass through, but water vapor is absorbed by this thin layer because the dense thin layer has hygroscopic properties. It is adsorbed on the surface of water, aggregates and becomes liquid water,
It is possible to permeate the porous member by moving the capillary existing in the dense thin layer by capillary force, reaching the back surface of the porous member, and vaporizing again from this back surface.

Further, the liquid water filling the capillary tubes can sufficiently prevent gas from permeating through these capillary tubes,
This will provide a high degree of gas selective permselectivity.

In this way, the moisture-permeable gas shield obtained by the method of the present invention can be used as it is or in a stacked manner, for example, in a total heat exchanger for air conditioning equipment. The fresh air taken in and the dirty air discharged from indoors to outdoors are not mixed.
Heat exchange and latent heat of water vapor can be exchanged.

As a result, the total heat exchanger not only has high heat recovery efficiency, but also reduces indoor humidity changes, which is extremely advantageous in terms of hygiene management.

Further, since this moisture-permeable gas shield has permeation selectivity for gas molecules, it can be used in a wide range of fields other than the heat exchanger.

This invention will be described below with reference to embodiments.

Example 2 A pulp containing rosin, which is a natural sizing agent, was made into paper to obtain a weak water-based industrial paper 1 shown in FIG. 1.

After drying this Sawagami, we measured the size of Sawagami]
, it was 80 seconds.

Next, an aqueous solution containing 3.5% by weight of lithium chloride and 12% by weight of polyvinyl alcohol is prepared, and after immersing the weakly kneaded water-based paper, that is, the porous member, in the aqueous solution for 10 to 20 seconds using a treater device, The excess aqueous solution was scraped off within 40 to 60 seconds using an edge, and the film was immediately carried into a drying oven, dried, and then rolled up.

In the moisture-permeable gas shield obtained as described above, a dense hygroscopic thin layer is formed on the surface layer of industrial grade paper, and the content of lithium chloride and polyvinyl alcohol is 26% by weight.
Met.

The cross-section of this moisture-permeable gas shield has the structure shown in FIG. 2, and when observed with an electron microscope, the lithium and polyvinyl alcohol are relatively present on the surface layer of the weakly wrenable porous member 10 made of industrial paper. A thin hygroscopic layer 2 was formed which was dense and had a porous membrane shape in which capillaries of several microns were present.

Example 2 Western paper with a sizing degree of 100 seconds was obtained by paper-making a raw material pulp containing a synthetic sizing agent, Polymalon, as a sizing agent.

An aqueous solution containing 7.0% by weight of lithium chloride and 24% by weight of hydroxyethyl cellulose was prepared on this weakly kneaded water-based Western paper, and a coating was applied to the upper surface of the Western paper using a coating device.

This was quickly coated and passed through a drying oven and wound up.

The cross section of the moisture-permeable gas shield obtained as described above has the structure shown in FIG. A thin hygroscopic layer 2 in the form of a porous membrane with dense capillaries of several microns in size was formed on the surface layer.

Reference Example A moisture-permeable gas shield as shown in FIG. 4 was prepared in the same manner as in Example I described above, using industrial grade paper with a sizing degree of 1 second or less that had not been subjected to a weak water refining treatment. Obtained.

Since this moisture permeable gas shielding material has not been subjected to a weak water mixing treatment, the polymer material 7 containing the moisture absorbent is impregnated into the inside of the porous member 1' made of a piece of paper. The content was 35% by weight.

The properties (a) of the moisture-permeable gas shields obtained in Examples (1), (2) and Reference Examples and the properties (b) when these were used in a total heat exchanger were as shown in the table below.

Note that (a) shown in the above clothing was measured on the plate-shaped samples obtained in the above Examples and Reference Examples, and (b)
The results were measured by manufacturing a total heat exchanger using the above-mentioned plate-shaped material.

Further, the specific gas leakage rate was measured using carbon dioxide gas.

As is clear from the above-mentioned clothing, the products obtained in Examples I and ① of this invention have higher heat exchange efficiency (sensible heat) and humidity exchange efficiency (latent heat) than those obtained in Reference Example. The improvement in specific gas leakage rate is remarkable.

As described in detail above, the present invention uses a porous member that has been slightly wetted, and forms a thin layer of a hygroscopic polymer material thereon to produce a moisture permeable gas shield.
This has the effect of providing a moisture-permeable gas shield with low air permeability while maintaining good moisture permeability.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of a porous member subjected to weak water mixing, and FIGS. 2 and 3 show moisture-permeable gas shields obtained by the manufacturing methods of Examples ① and ② of the present invention, respectively. Cross-sectional view, FIG. 4 is a cross-sectional view of a moisture-permeable gas shield obtained by a manufacturing method of a reference example. 1...Weak water-wetting porous member, 1'...
Porous member, 2... Thin layer of hygroscopic polymeric material, 2'... Hygroscopic polymeric material. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A weakly kneaded water-based porous member having a sizing degree of 20 to 200 seconds is impregnated, applied or coated with an aqueous solution of a polymeric substance containing a moisture absorbent, and the aqueous solution reaches the inside of the porous member. A method for producing a moisture-permeable gas shield, which comprises drying the porous material and forming a thin layer of a polymeric substance containing a moisture absorbent on the surface layer of the porous member before penetration. 2. The method for producing a moisture-permeable gas shield according to claim 1, wherein the weakly water-wetting porous member is a non-hydrophobic porous member impregnated with a weakly water-wetting material. 3. The method for producing a moisture-permeable gas shield according to claim 2, in which paper is used as the non-hydrophobic porous member. 4. The method for producing a moisture-permeable gas shield according to claim 2, in which cloth is used as the non-hydrophobic porous member. 5. The method of manufacturing a moisture-permeable gas shield according to claim 2, in which ceramic is used as the non-hydrophobic porous member. 6. The method for producing a moisture-permeable gas shield according to claim 2, in which a natural sizing agent is used as the weakly water-dispersible material. 7. The method for producing a moisture-permeable gas shield according to claim 2, using a synthetic sizing agent as the weak water-dispersing material. 8. The method for producing a moisture-permeable gas shield according to claim 1, using lithium chloride as the moisture absorbent. 9. The method for producing a moisture-permeable gas shield according to claim 1, using water-soluble polyvinyl alcohol as the polymeric substance.