JPH0773654B2 - Method of manufacturing moisture exchange element - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method of manufacturing a moisture exchange element. More specifically, it relates to a method for manufacturing a honeycomb type moisture exchange element in which a solid adsorbent is deposited on the surface.

[0002]

2. Description of the Related Art As a method of dehumidifying an air or a moisture gas mixture with a solid desiccant, a static drying method and a dynamic drying method have been well known. Among them, the static drying method removes moisture from calcium sulfate,
It is a method of dehumidifying by bringing it into contact with a hygroscopic desiccant such as potassium hydroxide or potassium chloride. Since this static drying method cannot regenerate the solid desiccant in situ after absorbing moisture, it cannot secure a satisfactory moisture absorbing ability when it is carried out for a long time. Therefore, it is not suitable for dehumidification by mass circulation of moisture. On the other hand, the dynamic drying method is a continuous method in which moisture absorption and regeneration of the adsorbent are simultaneously performed, and usually, for example, silica gel, molecular sieve, alumina, etc. are used, and a two-column fixed bed dehumidifier or a rotary honeycomb rotor dehumidifier is used. Machine. The two tower type fixed bed dehumidifier is mainly composed of two towers, which are respectively filled with adsorbent particles, and moisture is sent from the first tower to the second tower, and regenerated hot air is sent from the second tower to the first tower. There is a valve to send. This type of dehumidifier has the drawbacks of significant energy consumption due to the large pressure gradient of the fixed particle bed and humidity fluctuations of the dehumidified air. On the other hand, rotary honeycomb low
The dehumidifier has a low-speed rotating rotor consisting of a cylindrical matrix with long passages and an adsorbent that deposits on the surface of the matrix, and introduces moisture and regenerated hot air into two different parts of the rotating rotor simultaneously. Desorb the adsorbent periodically during the continuous dehumidification process. This rotary honeycomb rotor dehumidifier has the following advantages. That is, the pressure gradient through the rotor is low, the absorption area per unit volume is increased, and absorption / desorption is fast and effective. As a result, the energy consumption is low, the dehumidification efficiency is increased, and the operation is easier than that of the double tower fixed bed dehumidifier.

As a preferable moisture exchange element (moisture exchange honeycomb rotor ) used in the rotary dehumidifier, one having a small heat capacity, a light weight, excellent mechanical characteristics and a high moisture absorption capacity is desired.

Conventionally, the following method has been known as a method for manufacturing a moisture exchange element.

The method of manufacturing a moisture exchange element disclosed in Japanese Patent Laid-Open No. 55-142522 is such that a flat air-permeable sheet such as paper is impregnated with a solution of a hygroscopic agent such as an aqueous solution of calcium chloride, and the corrugated sheet is dried. In this method, the corrugated sheet is not impregnated with the hygroscopic agent solution, and the strength is not impaired by a method of forming a block-shaped moisture exchange element by cutting the material into a predetermined size, cutting it to a predetermined size, impregnating it with a reinforcing agent and alternately laminating it.

A method of manufacturing a dehumidifying / exchange element having small through holes disclosed in Japanese Patent Laid-Open No. 175521/1985 is a method in which a paper made of organic fibers and inorganic fibers is molded into a shape of an element having a large number of small holes. , The obtained molded body is heated under insufficient supply of oxygen to carbonize the organic components in the molded body, the molded body is impregnated with an inorganic reinforcing agent before or after the carbonization step, and finally with a hygroscopic agent. Is the way to do it.

However, all of these methods are complicated in operation. In the method described in JP-A-55-142522, since the impregnating liquid is calcium chloride or lithium chloride, it becomes a hydrate after moisture absorption and is regenerated. Is not easy, and the method described in JP-A-60-175521 is characterized in that the organic component in the fiber molding is heated and carbonized under the condition of insufficient oxygen. No improvement has been added to the liquid.

In the method of manufacturing a moisture exchange element disclosed in Japanese Patent Laid-Open No. 63-175619, water glass is impregnated with paper made of inorganic fibers such as ceramic fibers and pulp, and the paper is semi-dried, and then a pair of Corrugated paper is corrugated with a roller to obtain corrugated paper, which is dipped in acid to form silica hydrogel, washed with water and dried. Put glue on this pile of corrugated paper,
It is a method of immediately rolling up with a roller along a silica hydrogel-coated flat paper to form a moisture exchange honeycomb rotor .

The method disclosed in JP-A-63-175619 has some problems in addition to the complicated operation. It is mainly due to the use of water glass. For example,
Due to the high content of sodium ions in water glass, the gelation rate is unduly fast. As a result, the impregnation life of the water glass bath is short and the properties of the impregnated paper change when the water glass bath is used for a certain period of time. Since the gelation speed is too fast,
The average pore size of the silica hydrogel moisture absorbent formed is about 20 Å. A hygroscopic agent having such an average pore size does not have a satisfactory hygroscopic ability, must be frequently desorbed, and is not suitable for high moisture absorption. Further, since the gelation speed is too high, it is difficult to semi-dry the impregnated paper until it is suitable for forming into a corrugated shape. On the other hand, the pH of water glass is about 11.5
Therefore, a large amount of acid is required for the acid-catalyzed gelation reaction. The sodium salt produced as a by-product in the acid-catalyzed gelation reaction deposits on the paper and not only increases the weight of the absorbent paper, but also closes the pores of the absorbent, so a washing step is indispensable. Nevertheless, the sodium salt remains on the paper after washing. The remaining sodium salts move one after another during the adsorption / desorption operation, which adversely affects the life of the dehumidifier. other than this,
The silica hydrogel formed on the paper is washed off with the sodium salt during the washing process. In particular, washing with water takes time and labor, and requires a large amount of water and complicated wastewater treatment.

The present invention does not have the above-mentioned drawbacks, has a smaller number of steps than the prior art, is easy to operate, deposits a large amount of a hygroscopic agent on a substrate, and enhances the hygroscopic capacity of the hygroscopic agent. An object is to provide a method for manufacturing a device.

[0011]

In order to achieve the above-mentioned object of the present invention, the present inventors impregnated a base material composed of organic or inorganic fibers into an impregnation aqueous solution containing colloidal silicic acid , an acid and a metal cation. Then, a method for producing a moisture exchange element which is dried and gelled has been found.

That is, according to the present invention, a base material made of organic or inorganic fibers is added to 5 to 20% by weight of colloidal silicic acid , 0.25
~ 2.5% by weight of water-soluble metal salt and pH of impregnating solution 5 ~
The present invention relates to a method for producing a moisture exchange element, which comprises impregnating an impregnating aqueous solution containing an acid in an amount sufficient to adjust to 9 and then drying the impregnating solution deposited on the base material under heating to cause gelation.

The device preferably has a honeycomb structure.

[0014]

[Example] The fiber substrate used in this production method has a density of 0.5 g / c.
A porous material having a size of m or less, preferably a ceramic fiber, a carbon fiber, a glass fiber, a polymer fiber or the like, which may be a woven cloth or a non-woven cloth. The base material has a thickness of 0.10-0.
60mm flat strip or wave height 0.4 made from this flat strip ~
It may be a corrugated strip having a 2.0 mm wavelength and a wavelength of 0.4 to 4.0 mm, or a honeycomb block body or rotor formed by laminating the planar strip and the corrugated strip one by one. The term "strip" as used herein means a long tape shape (strip).

[0015] waveforms conditions and the honeycomb block body or b
The data can be made by any suitable method known in the art. Preferably, the flat strip is passed through a pair of specific rollers or a gear roller / toothed plate, and the corrugated silicic acid adhesive aqueous solution is immediately applied to the wave surface, and dried by heating at 80 to 120 ° C. for 40 to 90 minutes to fix the waveform. , Forming corrugations. The lamination of the corrugated strip and the flat strip is performed by first impregnating the flat strip with an adhesive solution, placing it on the corrugated strip, and heating the laminated strip at 80 to 120 ° C. for 40 to 90 minutes. The concentration of colloidal silicic acid in the adhesive liquid is 5 to 25% by weight, preferably 8 to 15% by weight. If this concentration is too high, the colloidal silicic acid will block the pores in the flat and corrugated strips, reducing the ratio of hygroscopic agent to substrate in the moisture exchange element formed by these strips. If this concentration is too low, the corrugated strips and the honeycomb block body or
The mechanical strength of the rotor becomes insufficient. The method for manufacturing a moisture exchange honeycomb rotor in a preferred embodiment is such that a corrugated strip is formed by using an impregnating liquid as an adhesive liquid, a flat strip is impregnated with the impregnating liquid, the corrugated strip is wound up along the impregnating strip, and the corrugated strip is wound at 250 ° C. for 3 hours. Heat for hours. Since only one type of colloidal silicic acid solution is used in this method, the entire structure of the moisture exchange element is uniform, and the adhesion between the corrugated strip and the flat strip is strong.

The metal salt used in the method of the present invention may be any one as long as it dissolves in an aqueous solution and does not adversely affect the impregnated substrate.
Both are used to provide the metal cations of the impregnating liquid. Preferred are inorganic salts such as halides , nitrates, hydroxides and sulfates. The metal cations used are Li, Ca, Al, Mg, Ni, F
Examples include cations such as e, Zn, and Cu. Among them, L
i and Ca are preferable.

The acid used in the present invention is, for example, sulfuric acid,
Inorganic acids such as nitric acid and hydrochloric acid are preferred.

In the method of the present invention, the impregnating solution deposited on the impregnated substrate is dried and gelled by applying 100-400 to the impregnated substrate.
It is carried out by heating at 40 ° C. for 40 minutes to 8 hours.

In this production method, an aqueous solution impregnated with colloidal silicic acid is used, but the content of sodium ions is remarkably lower than that of water glass, and since sodium ions are hardly generated during the gelation reaction of silica, a water washing step is unnecessary. Is. Further, since the pH before the addition of acid is about 9.0, the amount of acid required for neutralization is remarkably lower than that of water glass. And since the impregnation solution contains an appropriate amount of metal cations,
In addition to being able to maintain a stable sol-gel state for a considerably long time at room temperature, naturally, upon heating for drying and gelation, metal cations act as catalysts to promote the gelation reaction to occur in the impregnating solution. Further, the moisture exchange element according to the present invention has a higher ratio of the hygroscopic agent to the substrate than the method using water glass, and the average pore diameter of the hygroscopic agent deposited therein is about 60 to 70.
Angstrom. Therefore, the moisture exchange element according to the present invention has excellent moisture absorption / desorption ability. In the preferred embodiment, 1 gram of the absorbent at 80% relative humidity absorbed 0.7 to 0.8 grams of water.

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to such examples as a matter of course. Unless otherwise specified, all parts and% are parts by weight and% by weight, respectively, and the average pore size is determined by the BET nitrogen adsorption method according to the Micromeritic Digisorb 2600 instrument (Micromeritics). (Made in USA)
It was measured at. Further, the dehumidification test was conducted at 20 ° C. and 79.5% relative humidity, and the characteristics and moisture absorption of the moisture exchange element were defined as follows: Moisturizer deposition ratio (ADR)% = {(weight of moisture exchange element) − (Weight of fiber base)} / (Weight of fiber base) x 100 Element moisture absorption (MAE)% = {(weight after element moisture absorption)-(weight before element moisture absorption)} / (before element moisture absorption) Weight) x 100 Moisture absorption (MAA)% = {(weight after absorbing element)-(weight before absorbing element)} / {(weight of element)-(weight of fiber base)} x 100 Example 1: Manufacture of honeycomb rotor 12.5 kg of 40% colloidal silicic acid (Ludox SM)
An adhesive solution (solution A) was prepared by adding 37.5 kg of water to an aqueous solution (manufactured by Dupont (USA)) with stirring.
425.1 g of a ceramic paper strip (made by Kaowool Inc.) having a width of 30 cm and a thickness of 0.5 mm is placed on the tooth plate and formed by the tooth roller, and the solution A is applied on the wave front thereof,
After heating at 100 ° C for 1 hour, 454.9 g of a corrugated strip having a wavelength of 0.6 mm and a wave height of 0.4 mm was obtained. The same ceramic paper was impregnated with solution A, immediately rolled up with a corrugated strip and heated at 100 ° C. for 1 hour. The obtained honeycomb rotor weighed 920.7 g and had a diameter of 40 cm.

Example 2: Preparation of impregnation liquid and deposition of hygroscopic agent 1.0 kg of LiCl was added to 1.0 L of water, and the solution obtained by stirring for 15 minutes was poured into the solution A of Example 1 to obtain pH 7.0. 0.1N sulfuric acid was added to and stirred for 15 minutes. The honeycomb rotor of Example 1 was immersed in this neutral solution for 1 hour, then taken out, dried at room temperature, and heated in an oven at 250 ° C. for 3 hours. The obtained honeycomb rotor weighs 1316.9 g,
The characteristics and moisture absorption are shown in Table 1.

Example 3 In this example, in the manufacture of a honeycomb substrate, the adhesive liquid is replaced with an impregnating liquid to obtain a moisture exchange honeycomb rotor which can be directly used as a moisture exchange element.

A corrugated strip 447.8 g was prepared as in Example 1, except that 418.5 g of the ceramic and the impregnating liquid of Example 2 were used. The impregnating liquid was also used for bonding the flat strip and the corrugated strip to obtain a honeycomb rotor (1146.3 g, diameter 40 cm). The characteristics and moisture absorption are shown in Table 1.

Example 4 A moisture exchange rotor was prepared as in Example 2 except that 0.5 kg of LiCl was used. The characteristics and moisture absorption are shown in Table 1.

Example 5 A moisture exchange rotor was prepared as in Example 2, except that 2.0 kg of LiCl was used. The characteristics and moisture absorption are shown in Table 1.

Comparative Example 1 A moisture exchange rotor was manufactured in the same manner as in Example 2 except that LiCl was not used. The characteristics and moisture absorption are shown in Table 1.

Comparative Example 2 3 kg of water glass was added to 48 L of water, and after sufficiently stirring, a solution of 1.0 kg of LiCl in 1.0 L of water was added and stirred for 15 minutes. 931.2 g of the honeycomb rotor manufactured in Example 1 was immersed in the obtained water glass solution for 1 hour,
0.1N sulfuric acid was added with stirring until the pH was 7.0. The rotor was removed before the solution gelled, dried at room temperature and then placed in an oven at 250 ° C for 3 hours. The dry rotor weighs 1286.3g and its characteristics and moisture absorption are shown in Table 1.
It was shown to. The gelling rate of the impregnating liquid of this comparative example was high, and it could not be used after gelling.

Comparative Example 3 A moisture exchange rotor was manufactured in the same manner as in Comparative Example 2 except that LiCl was not used as the impregnating liquid. Its characteristics and moisture absorption are shown in Table 1.
It was shown to. The impregnating liquid of this comparative example gelled within 30 minutes and could not be used.

Example 6 The same operation as in Example 2 was carried out except that the impregnating liquid was left at room temperature for 5 days before impregnating the substrate. The results are shown in Table 2.

Example 7 The same operation as in Example 5 was carried out except that the impregnating liquid was left at room temperature for 3 days before impregnating the substrate. The results are shown in Table 2.

Comparative Example 4 The same operation as in Comparative Example 1 was carried out except that the impregnating liquid was left at room temperature for 5 days before impregnating the substrate. The results are shown in Table 2.

Comparative Example 5 The same operation as in Comparative Example 2 was carried out except that the impregnating liquid was left at room temperature for 3 days before impregnating the substrate. The results are shown in Table 2.

Comparative Example 6 The same operation as in Comparative Example 3 was carried out except that the impregnating liquid was left at room temperature for 1 hour before impregnating the substrate. The results are shown in Table 2.

[0034]

[Table 1]

[0035]

[Table 2]

From the results shown in Tables 1 and 2, it can be seen that this method is superior in moisture absorption and stability to the water glass method.

Examples 8 to 15 The procedure was the same as in Example 2 except that different compositions were used for the impregnating liquids. The results are shown in Table 3. The impregnating solution of Example 8 was 25 kg instead of 12.5 kg of 40% colloidal silicic acid aqueous solution.
Examples 9 to 13 used LiOH, LiNO ₃ , CaCl ₂ , Al ₂ (SO ₄ ) instead of LiCl, respectively.
₃ , CuSO ₄ was used, and Examples 14 and 15 had a pH of 6.0.
And 8.3 impregnating solutions were used respectively.

[0038]

[Table 3]

[0039]

According to the method of the present invention, it is possible to easily obtain a moisture exchange element having a high hygroscopic capacity, containing a large amount of a hygroscopic agent and having an appropriate pore size, in a small number of steps.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Xiao Chun Chu Taiwan, Xin Chu, Kang Road, Section 2, 321 (72) Inventor Han Qin Chang Taiwan, Xin Chu, Kang Road, Section 2, 321 (72) Inventor Qing Xuan Fan Taiwan, Xin Chu, Kang Road, Section 2, 321 (72) Inventor Chang Qing Cheng Taiwan, Xin Chu, Kang Road, Section 2, 321 (72) Inventor Po Yui Cheng Taiwan, Xin Chu, Kang Flood, Section 2, 321

Claims (7)

[Claims] 1. A substrate comprising organic or inorganic fibers,
After impregnating an aqueous solution containing 5 to 20% by weight of colloidal silicic acid , 0.25 to 2.5% by weight of a water-soluble metal salt and a sufficient amount of acid to adjust the pH of the impregnating solution to 5 to 9, A method for producing a moisture exchange element, characterized in that the deposited impregnating liquid is dried under heating to be gelled. 2. The metal salt is selected from the group consisting of halides , nitrates, hydroxides and sulfates.
The manufacturing method described. 3. The metal is Li, Ca, Al, Mg, Ni,
The method according to claim 2, wherein the method is selected from the group consisting of Fe, Cu and Zn. 4. The method according to claim 1, wherein the acid is an inorganic acid. 5. Drying and gelling at 100-400 ° C. for 40 minutes-
The method according to claim 1, which is carried out for 8 hours. 6. The base material has a wave height of 0.4 to 2.0 mm and a wavelength of 0.4 to 4.
2. The manufacturing method according to claim 1, wherein the honeycomb structure has a corrugated strip of 0 mm and a flat strip having a thickness of 0.10 to 0.60 mm. 7. A flat fiber strip is pressed into a corrugated surface, and the corrugated surface has 5 to 20% by weight of colloidal silicic acid and 0.25 to 2.5% by weight.
Of the water-soluble metal salt and the impregnating solution of an acid in an amount sufficient to adjust the pH of the impregnating solution to 5 to 9 are applied, and the applied strip is fixed to the corrugation by heating. was impregnated with the impregnation solution, immediately rolled up honeycomb rotor the impregnated flat fiber strip with the waveform conditions, the honeycomb b
A method for manufacturing a moisture exchange honeycomb rotor , which comprises heating a rotor and drying the impregnating liquid contained therein to cause gelation.