JPH10272334A - Method of manufacturing dehumidifying element - Google Patents

Abstract

(57) [Problem] To obtain a dehumidifying element having a sufficient dehumidifying function even in one processing step by using an inorganic fiber paper coated with silica gel in advance. SOLUTION: The surface of the inorganic fiber paper is coated with silica gel,
After the inorganic fiber paper coated with the silica gel is processed into a honeycomb shape to obtain a honeycomb-shaped processed product, the honeycomb processed product is immersed in an aqueous alkali silicate solution, subjected to an acid treatment, and then fired. Method for producing a dehumidifying element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a dehumidifying element carrying silica gel.

[0002]

2. Description of the Related Art As a dehumidifying element incorporated in a regenerative dehumidifier, a total heat exchanger, or the like, a dehumidifying agent such as silica gel, zeolite, or deliquescent inorganic salt is applied to the surface of honeycomb-shaped inorganic fiber paper. What is carried is known.
Above all, a dehumidifying element using silica gel as a dehumidifying agent has become mainstream because it has advantages such as easy regeneration and low cost in addition to high dehumidifying performance.

Conventionally, as a method for producing a dehumidifying element in which silica gel is supported on a honeycomb structure, a honeycomb structure made of inorganic fiber paper such as glass paper or ceramic paper is immersed in an aqueous alkali silicate solution and then treated with an acid. A method of drying the honeycomb structure, immersing the honeycomb structure in an aqueous solution of alkali silicate and then drying it, and then performing an acid treatment, or a method of immersing the honeycomb structure in an aqueous solution of alkali silicate and then adding a water-soluble calcium salt. Alternatively, a method of immersing in an aqueous solution of a magnesium salt and then performing an acid treatment is known.

[0004]

The process of producing silica gel by treating an alkali silicate with an acid is complicated and requires a large number of steps. Therefore, it is preferable that only one step is required if it is possible to manufacture a dehumidifying element. However, in the above-mentioned process, the amount of silica gel deposited per one time is limited, and in consideration of use as a dehumidifying element, the above process must be repeated several times in order to deposit silica gel necessary for performance. . In other words, increasing the concentration of alkali silicate increases the amount of silica gel produced and increases the amount of adhesion,
The alkali silicate aqueous solution has a high viscosity, and if the concentration is increased, the honeycomb structure is clogged. Therefore, the amount of silica gel adhered per time is limited, and the process is necessarily repeated several times.

The present invention has been made in view of such a situation, and uses an inorganic fiber paper coated with silica gel in advance to provide a dehumidifying element having a sufficient dehumidifying function even in one processing step. The purpose is to obtain.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a honeycomb-shaped processed product obtained by coating silica gel on the surface of inorganic fiber paper and processing the inorganic fiber paper coated with silica gel into a honeycomb shape. After that, the honeycomb-shaped workpiece is immersed in an alkali silicate aqueous solution, subjected to an acid treatment, and then fired, thereby achieving a method for manufacturing a dehumidifying element.
According to the method of the present invention, most of the silica gel adhesion amount required for the dehumidifying element is secured by the coated silica gel, so that the step of producing silica gel by the acid treatment of alkali silicate can be performed only once. Further, according to the method of the present invention, the coated silica gel and the silica gel obtained by the acid treatment of the alkali silicate form an integral film, and the shape as the dehumidifying element is stably maintained.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing a dehumidifying element according to the present invention will be described in detail. The inorganic fiber paper forming the honeycomb structure serving as the base material of the dehumidifying element is not particularly limited as long as it is conventionally used for the honeycomb structure of this type of dehumidifying element. And ceramic fibers assembled in paper form. In particular, in consideration of the deterioration due to the acid treatment when producing the silica gel and the mechanical strength and durability of the honeycomb structure, a fiber made of E glass or a paper made of silica alumina fiber having a small amount of alkali component is preferable.

To coat the inorganic fiber paper with silica gel, a coating liquid is prepared by mixing silica gel, polyvinyl alcohol or an acrylic or vinylidene chloride-based organic emulsion and water, and then preparing this coating liquid. Can be applied to the surface of the inorganic fiber paper using a spray or a brush, or a method of immersing the inorganic fiber paper in a coating liquid. Above all, a method of immersing the inorganic fiber paper in the coating liquid is simple and preferable. This coating causes the silica gel particles to adhere to the surface of the inorganic fibers via the organic emulsion. The type of silica gel used for the coating liquid is not particularly limited, and those having a moisture absorption of 3.0% or more at a relative humidity of 20% specified in JIS Z0701 can be used. The coating amount of the coating liquid is preferably 30 to 120 g / m ² in terms of silica gel. If the coating amount is less than 30 g / m ² , the silica gel generation step described below cannot be completed only once in order to obtain the amount of silica gel required for the dehumidifying element. On the other hand, when the coating amount is more than 120 g / m ^2, clogging occurs due to too many silica gel particles adhering to the inorganic fibers.

After coating, the excess silica gel adhering to the inorganic fiber paper is removed in order to uniformly perform the reaction of forming silica gel described later and to exert a uniform dehumidifying action as the whole dehumidifying element. Preferably, the coating surface is flat. Then, the coated inorganic fiber paper is dried and processed into a honeycomb shape to obtain a honeycomb structure as a base material of the dehumidifying element. The shape of the honeycomb structure is not particularly limited, and is processed in accordance with the type, application, and location of the dehumidifying element.

The thus obtained honeycomb structure coated with silica gel is immersed in an alkali silicate aqueous solution,
Next, the alkali silicate is converted into a silica gel by an acid treatment. The resulting silica gel is converted into silica gel by the subsequent dehydration (calcination), and the particles are formed so as to bond with the silica gel particles adhered to the surface of the inorganic fiber by coating or to fill the space between the silica gel particles. . This silicic acid gel formation reaction can be performed by a known method. For example, as the aqueous alkali silicate solution, an aqueous solution of about 10 to 30% of sodium silicate, potassium silicate, lithium silicate or the like is suitable. Even if the concentration of the alkali silicate is lower than this, it is possible to fix the silicate gel, but the fixing amount is too small, and the object of the present invention to manufacture the dehumidifying element by only one step cannot be achieved. Conversely, if the concentration is too high,
Not only does the viscosity increase, causing clogging, but also it does not penetrate smoothly between the inorganic fibers of the honeycomb structure, and new silica gel particles cannot be generated so as to fill the silica gel particles by coating.

When the aqueous alkali silicate solution sufficiently penetrates into the inter-fiber voids of the inorganic fiber paper of the honeycomb structure, the honeycomb structure is taken out of the aqueous alkali silicate solution and, if necessary, is blown with a high-speed air stream or the like, to thereby remove the excess. Excluding liquid adhering to the surface. Next, the honeycomb structure impregnated with the alkali silicate aqueous solution is subjected to an acid treatment to convert the silicate into a silicate gel. Examples of usable acids include hydrochloric acid, nitric acid, and sulfuric acid, and organic acids can also be used. In addition, a salt capable of eluting an alkali from an alkali silicate can be used, and examples thereof include ammonium chloride and ammonium nitrate. The acid treatment is performed by immersing the honeycomb structure impregnated with the alkali silicate aqueous solution in the above acidic aqueous solution.

Prior to the acid treatment, the honeycomb structure impregnated with the aqueous alkali silicate solution may be immersed in an aqueous solution of a water-soluble calcium salt or magnesium salt, for example, calcium chloride, magnesium chloride, magnesium nitrate or the like. The preferred concentration of these salt solutions is about several% to about 30%, and the suitable immersion temperature is normal temperature to 70 ° C. By this treatment, the alkali silicate that has simply adhered to the honeycomb structure is converted into insoluble calcium silicate or magnesium silicate and fixed to the surface of the inorganic fibers. In addition, due to this treatment, most of the calcium ions or magnesium ions remaining in the form of calcium silicate or magnesium silicate are eluted into the treatment liquid during the acid treatment, affecting the dehumidifying performance of the dehumidifying element. Never. The details of this processing can be referred to Japanese Patent Application Laid-Open No. 63-218235 by the present applicant.

After the silica gel is formed as described above, the honeycomb structure is washed with water to remove the attached salts, and then dried with hot air. In this state, since the organic emulsion contained in the coating liquid remains so as to cover the surface of the silica gel particles attached to the inorganic fibers, the attached silica gel particles have a low dehumidifying ability as they are. Therefore, for the purpose of removing the organic emulsion, for example, about 400 to 50
It is preferred that the temperature be raised to 0 ° C. for firing. In addition, when the inorganic fiber paper of the honeycomb structure contains organic fibers and organic binders, these are also removed by this baking at the same time.

Thus, a dehumidifying element can be obtained, but the acid treatment of the alkali silicate is performed once, and the manufacturing process is significantly simplified.

Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples. (Example) An E glass fiber paper (30 g / m ² in basis weight and 0.2 mm in thickness) is coated so as to have a silica gel content of 60 g / m ² . The coating was performed by immersing E glass fiber paper in a slurry obtained by mixing A-type silica gel, an acrylic organic emulsion, and water, and then pulling it up and, at the same time, scraping off excess silica gel and drying. The coated paper is corrugated and then wound, and has a diameter of 400 mm and a length of 200 mm.
mm was manufactured. The honeycomb structure was immersed in a sodium silicate solution having a solid concentration of 28% for 30 minutes, then immersed in a 10% calcium chloride solution at 50 ° C. for 30 minutes, and further immersed in 5% hydrochloric acid at room temperature for 3 minutes.
Dipped for 0 minutes. Next, the honeycomb structure taken out from the hydrochloric acid was washed with water, dried at 110 ° C.
Fired at ℃. Table 1 shows the characteristic values of the obtained dehumidifying element A. Table 2 shows the results of measuring the dehumidifying ability by incorporating the dehumidifying element A into a rotary regeneration type dehumidifier.

(Comparative Example) E glass fiber paper (with a basis weight of 30 g /
(m ² , thickness: 0.2 mm) was corrugated and then wound to produce a rotor-type honeycomb structure having a diameter of 400 mm and a length of 200 mm. This honeycomb structure was immersed in a No. 1 sodium silicate solution having a solid concentration of 28% for 30 minutes.
After that, draining and air blowing are performed,
% For 30 minutes in an aqueous solution of calcium chloride at a temperature of 50 ° C., and further for 30 minutes at room temperature in 5% hydrochloric acid. Next, after washing the honeycomb structure taken out from hydrochloric acid with water,
It was dried at 100 ° C and subsequently calcined at 400 ° C. For the honeycomb structure to which the silica gel was fixed as described above, the treatment from immersion in an alkali silicate aqueous solution to drying was performed for 3 hours.
This was repeated to obtain a dehumidifying element B. Table 1 shows the characteristic values of the dehumidifying element B, and Table 2 shows the results of measuring the dehumidifying ability by incorporating the element into a rotary regeneration type dehumidifier.

[0017]

[Table 1]

[0018]

[Table 2]

From Tables 1 and 2, the dehumidifying element A of the example according to the present invention has a larger amount of silica gel carried out in one process than the dehumidifying element B of the comparative example, and the dehumidifying performance. It turns out that it is also excellent.

[0020]

As described above, according to the present invention,
After coating the surface of the inorganic fiber paper with silica gel, and processing the inorganic fiber paper coated with the silica gel into a honeycomb shape to obtain a honeycomb-shaped processed product, the honeycomb processed product is immersed in an alkali silicate aqueous solution, By baking after the acid treatment, it is possible to produce a dehumidifying element having performance suitable for practical use only by passing through one manufacturing process.

Claims (1)

[Claims] Claims: 1. Silica gel is coated on the surface of an inorganic fiber paper,
After the inorganic fiber paper coated with the silica gel is processed into a honeycomb shape to obtain a honeycomb-shaped processed product, the honeycomb processed product is immersed in an aqueous alkali silicate solution, subjected to an acid treatment, and then fired. Method for producing a dehumidifying element.