JPS63116727A - Dry dehumidifying material - Google Patents

Abstract

PURPOSE:To prevent the generation of liquid droplets from a dehumidifying material due to mosture absorption, by containing 75wt% or more of an Si- source in terms of SiO2 or containing 30wt% or more of the Si-source in terms of SiO2 and 5-40wt% of chloride. CONSTITUTION:As the base material of a dry dehumidifying material, 75wt% or more of a silica (Si) source (e.g., a silica gel) in term of SiO2 (a) is contained or 30wt% or more of the Si-source in terms of SiO2 and 5-40wt% of chloride (e.g., lithium chloride) (b) are contained to obtained the dry dehumidifying material. When this dehumidifying material is prepared, 2-25wt% a binder (e.g; colloidal silica) is pref. added in order to improve the moldabililty of the dehumidifying material and to obtained strength as a molding. Further, this dehumidifying material is pref. formed into a accumulated lumpy article of linear extrudates or a honeycomb shape. When this dehumidifying material is used as the dehumidifying rotary body of a dry dehumidifier, a problem such that an aqueous chloride solution due to moistuure absorption is scattered with rotation can be solved.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a dry dehumidifying material. A large number of dehumidification machines are used in There are various dehumidification methods, such as a cooling type, an absorption type (wet type), a compression type, an adsorption type, and an absorption type (dry type).

Among these dehumidification methods, as the demand for dry air increases, absorption type (dry type) (hereinafter referred to as dry dehumidification machines), which can easily dehumidify air and provide air with a low dew point, is increasingly used. It became so.

As shown in Japanese Utility Model Application No. 58-28616, a dry type dehumidifying machine has a gas passage to be treated and a regenerating gas passage for regenerating moisture absorbing material, and is configured to freely rotate across both roads. Generally, a machine is provided with a dehumidifying material, and by rotating the rotary body, dehumidification from the gas to be treated and regeneration of the dehumidifying material that has been absorbed are alternately and continuously performed.

Dry dehumidifying materials used in such dry dehumidifying machines include: ■As shown in Japanese Patent Application Laid-Open No. 159827/1982, materials containing asbestos, plastic, or activated carbon are molded into a honeycomb shape. Furthermore, in order to further improve the moisture absorbing ability, there is a material in which the above-mentioned material is made to support a chloride such as lithium chloride or calcium chloride and is formed into a honeycomb shape.

[Problems to be solved by the invention] ■ Among dry dehumidifying materials, those that do not carry chlorides are rarely actually used because of their low moisture absorption ability.

■On the other hand, chloride-supported materials have improved moisture absorption ability compared to non-chloride-supported materials, but there is a problem in that the chlorides become an aqueous solution and scatter as the dehumidifying material rotates. .

This point will be discussed in more detail.

In other words, in the case of a dehumidifying material that carries such chlorides,
The water retention capacity of a dehumidifying material has a large effect on its moisture absorption ability.

However, when lithium chloride is used as the chloride, for example, the moisture in the gas to be treated is absorbed in the form of LiC particles ΦnH2O and becomes an aqueous solution.

Thus, when the water retention capacity of the material constituting the dehumidifying material exceeds its water retention capacity, droplets of lithium chloride aqueous solution are generated there, and these droplets are scattered as the dehumidifying material rotates.

As described above, when chloride is dispersed in the form of an aqueous solution, the chloride flows out from the dehumidifying material, resulting in a problem that the dehumidifying ability of the dehumidifying material gradually decreases.

Another problem is that the scattered aqueous chloride solution causes corrosion in processes using dry dehumidification machines.

Note that it can be easily inferred that the dehumidification performance improves as the chloride content in the dehumidifying material increases, but as mentioned above, this content is limited by the scattering of the chloride aqueous solution, and the dehumidification performance increases as the chloride content increases. The higher the water retention capacity of the material, the more it can be contained.

However, the water retention performance of materials containing asbestos, plastic, and even activated carbon is not fully satisfactory, and as a result, chloride content
In other words, there is a limit to the moisture absorption performance, and if you try to improve the performance, chloride will scatter during long-term use, causing problems such as performance deterioration and can corrosion.

[Means for solving the problem] The above problem is characterized by containing a Si source of 75 wt% or more in terms of SiO2, or containing a Si source of 30 wt% or more in terms of SiO2 and 5 to 40 wt% of chloride. This problem can be solved by using dry dehumidification materials.

As a result of numerous studies focusing on the above-mentioned circumstances, the inventor of the present invention has decided to select a material containing 75 wt% Si source in terms of SiO2 instead of asbestos, plastic, and activated carbon that have been conventionally used as dehumidifying material materials. , or Si
Contains 30 wt% of source in terms of SiO2 and 5% of chloride.
The present invention was completed based on the knowledge that the moisture absorption ability can be significantly improved by selecting a material containing ~40 wt%.

The present invention will be explained in detail below.

(Si source) The reason why the content of the Si source is set to be 75% or more in terms of SiO2 is that silica gel is used as the Si source, and the silica gel content is calculated by using a method that shows the relationship between the amount of SiO2 in terms of SiO2 and the amount of moisture absorption. From Figure 1, the amount of moisture absorption is determined by the amount of moisture absorbed by the Si source, SiO.
It increases as the 2-conversion value increases, and especially when it reaches about 70%, it starts to increase rapidly, and when it reaches 75% or more, the moisture absorption amount starts to increase further. Therefore, the content of Si source is SiO2
It was assumed that the content was 75% or more in terms of conversion.

2. In the experiment shown in Figure 1, colloidal alumina was used as a binder, and a honeycomb-shaped molded body with a size of 50 x 50 x 50 mm was heated at a temperature of 30°C and a relative humidity of 80%.
The test piece was left in an atmosphere for 24 hours, and the amount of moisture absorbed was determined from the change in weight of the test piece before and after the experiment.

In addition, in the experiment shown in Figure 1, silica gel was used as the Si source, but silica sand, silica stone,
11γ can be arbitrarily selected from zeolite, diatomaceous earth, silicate clay, shirasu, porous glass, silica gel, etc.

In particular, silica gel is advantageous in terms of performance, economy, etc.

Note that these Si[s] can be obtained as powder or granules.

(Chloride) The present inventor also found that the moisture absorption ability can be significantly improved by adding 5 to 40 wt% of chloride to a material containing 30 wt% or more of a Si source.

Next, the reason why the chloride content is 5 to 40 wt% and the Si source content is 30 wt% or more in terms of Si source is that if the chloride content is less than 5%, the moisture absorption performance is significantly reduced, so it is difficult to use as a dehumidifying material. Performance will be lower.

In addition, if the content exceeds 40%, droplets of chloride aqueous solution will be generated on the surface of the dehumidifier, and the droplets will scatter as the dehumidifier rotates, resulting in a decrease in the performance of the dehumidifier if used for a long time. This is because the problem of corrosion caused by droplets occurs.

Note that the higher the chloride content, the higher the moisture absorption ability of the dehumidifier, but in a range exceeding 25 wt%, the rate of improvement in moisture absorption ability due to an increase in chloride content decreases, so from the viewpoint of droplet generation, 25 wt% % or less (second claim).

Examples of chlorides include lithium chloride and calcium chloride. In particular, lithium chloride is preferable from the viewpoint of performance (
3rd claim).

Method for Incorporating Monochloride In order to contain chloride, for example, a molded product formed into a desired shape, dried and/or fired may be impregnated with an aqueous solution of chloride, and then dried.

There are no particular restrictions on the method of impregnating this aqueous chloride solution, and any conventional method may be followed.The method described above is a method in which a porous silica molded body is obtained and then a chloride is supported on this molded body. A method may also be used in which chloride is added from the time of mixing and kneading, followed by molding.

When the chloride content is 5 to 40 wt%, and the Si source is increased to 30 wt% or more in terms of SiO2, the performance of the dehumidifying material begins to deteriorate rapidly, and its performance as a dehumidifying material cannot be fully demonstrated. Therefore, in this case, the Si source should be 30 wt% or more in terms of SiO2.

(Binder) In the process of manufacturing the dehumidifying material according to the present invention, it is preferable to add 2 to 25 wt% of a binder in order to improve the moldability of the dehumidifying material and to obtain strength as a molded product (No. 4). claims).

In this case, the reason why the amount of binder added is 2 to 25 Wt96 is that if the amount of binder added is 2% or less, there is no effect of adding the binder, and if the amount of binder added is 25% or less, there is no effect. %
This is because if it exceeds 100%, the surface of the Si source, for example, silica gel, may be covered with the binder, which may deteriorate the performance of the dehumidifying material.

There are no particular restrictions on the binder, as long as it exhibits a caking function.

Examples of organic materials include MC, CMC, ε powder,
CMS (carboxymethyl starch), HEC (hydroxyethyl cellulose), MPC (hydroxypropyl cellulose), sodium lignin sulfonate, calcium lignin sulfonate, polyvinyl alcohol, polyacrylic acid ester, polymethacrylic acid ester, phenolic resin, melamine resin, etc. Illustrated.

Examples of inorganic materials include colloidal silica, colloidal alumina, colloidal titanium, silicates,
Examples include aluminate, metal alkoxide, bentonite, kaolinite, seviolite, attapulgite, and aluminum phosphate.

Two or more of these organic binders and inorganic binders may be added.

In addition, in the case of a dry dehumidifying machine that performs reuse by heating, it is preferable to select an inorganic binder because the binder component does not deteriorate due to heating (first
(Claim 0) If the binder or the like contains a Si source, these are calculated as part of the Si source.

(Poronty) Note that it is preferable that the porosity of the molded body is 0.2 cc/g or more (fifth claim).

In this case, when the porosity is set to 0.2 c c / g or less, the number of open holes decreases and the moisture is absorbed near the surface of the dehumidifying material, so the amount of dehumidification becomes smaller compared to the size of the dehumidifying material. This is because dehumidification performance may deteriorate as a result. Here, porosity refers to the apparent volume of mercury, which is obtained by immersing a dehumidifying material that has completely deaerated the gas present in the micropores in pure mercury, sealing it, and pressurizing it to inject mercury into the micropores. The porosity was determined by dividing the value by the weight of the dehumidifying material.

(Manufacturing method) There are no particular restrictions on the method of manufacturing the molded body of the dehumidifying material, and a molding method suitable for the desired shape of the molded body may be selected.

After shaping, the dry dehumidifying material of the present invention can be obtained by drying and/or baking according to a conventional method.

Further, there are no particular restrictions on the mixing/kneading means, and known devices and equipment may be used as appropriate.

(Shape) The shape of the dehumidifying material is not particularly limited, and may be pellet-shaped,
The shape may be appropriately selected from beads, honeycombs, agglomerated shapes of linear extrudates, etc.

In addition, as a dry dehumidifying material, integral molding is preferable from the viewpoint of convenience in handling and wear resistance, and furthermore, from the viewpoint of pressure loss, the shape of an aggregate of linear extrudates (6th claim) or the shape of a honeycomb is optimal. (Claim 7).

When the dehumidifying material is used as a dehumidifying rotating body of a dry dehumidifier, heat-resistant rubber material or the like is used to ensure airtightness between both ends of the rotating body and the dehumidifying zone and regeneration zone, but this material is not used here. The heat-resistant rubber material used is generally a hard material when high-temperature regeneration is required. Therefore, both end faces of the molded product mainly composed of Si source are constantly rubbed by the moving contact material due to the rotation of the rotating body, which causes Jl wear and may even impair the airtightness between each zone. Become. In this case, a net or honeycomb-shaped strength reinforcing member made of metal, resin, or ceramic material may be attached to both end surfaces of the molded product in close contact with the molded product as much as possible, leaving no space between the ends of the molded product (claim 8). (Claim 9), or it is preferable to impregnate and coat both end surfaces of the molded body with an epoxy resin, phenol resin, etc. for reinforcement (Claim 9).

(Usage) Furthermore, the dehumidifying material obtained in the present invention can of course be used as a desiccant itself to dry the air in a predetermined container, and when conventional pellets or beads are used, it can be used as a desiccator. Although it was necessary to separate and nitride the desiccant in a dry storage container, as typified by the above method, it is also possible to juxtapose the dehumidifying material of the present invention, which allows for extremely simple use.

[Example of the invention] (Example 1) Using silica gel as the Si source, using Li0 or CaCJ12 as the chloride, and using colloidal alumina as the binder, chloride and Si02 were prepared according to a conventional method.
, A! Table 1 shows the results of tests conducted under the following conditions regarding dehumidification performance and droplet generation using dehumidification materials in the form of honeycomb shapes and linear extrudates with various L203 contents. : 150X150X10
Dehumidifying material with a size of 0 mm at a temperature of 30 degrees and a relative humidity of 80%
The amount of moisture absorbed by 1 cci of the dehumidifying material was determined from the change in weight of the dehumidifying material after the air to be treated was flowed at a wind speed of 1.5 m/s for 5 minutes, and that value was taken as the dehumidifying performance.

Generation of droplets 2. The above sample was heated to a temperature of 30 degrees and a relative humidity of 8.
The dehumidifying material was left in a 0% atmosphere for 24 hours, and the presence or absence of droplets on the surface of the dehumidifying material was examined.

As is clear from Table 1, the dehumidification performance is No. 1 according to the present invention.
, 3.4, 7, 8, 9, 10, and 12°14 all exhibit good moisture absorption ability. Especially No. 7.8,
No. 9, 12.1'4, those containing 75 wt% or more and chloride show better moisture absorption ability.

The generation of droplets is No. with lithium chloride content.

11.13,15. As shown in Figure 2, droplets were observed to occur when the concentration exceeded 40%.

In addition, in the range where the lithium chloride content exceeds 25 wt%, the rate of increase in moisture absorption due to the increase in content is small, so from the viewpoint of ease of generating droplets as mentioned above, from the viewpoint of safety, 25 wt% The following ranges are more desirable.

Nos. 1 and 2 have low SiO2 content (because the Si source is low), so their hygroscopic ability is low.

In No. 5, the SiO2 content was less than 30 wt%, so the effect of adding chloride was not obtained and the moisture absorption capacity was low.

N006 has low hygroscopicity because the amount of chloride added is low.

In addition, when the moisture absorption capacity of a commercially available dehumidifying material made of activated carbon sheet was investigated under the same conditions, it was found to be 0.06 g/CC.

(Example 2) In order to investigate the effect of adding a binder, silica gel was used as the Si source, bentonite was used as the binder, and LiC! was used as the chloride! ;
Based on the method previously described using L.

Honeycomb-shaped dehumidifying materials with various binder contents were fabricated.

The strength and moisture absorption capacity of the obtained dehumidifier were tested under the following conditions, and the results are shown in Table 2.

Strength: A 50x50x50 honeycomb-shaped molded body was used as a sample, and the second
As shown in the figure, the C-axis direction crushing strength was measured.

Moisture absorption capacity: The above sample was left in an atmosphere with a temperature of 30℃ and a relative temperature of 80% for 24 hours, and the moisture absorption amount (w) was determined from the weight change before and after moisture absorption.
t%) was determined.

As is clear from Table 2, No. 1.2, where the binder (bentonite) content is less than 2%, has a decreased crushing strength and No. 3, where the binder content exceeds 25 wt%, and No. 3, where the moisture absorption capacity has decreased. I found out that there is.

When the content of the binder (bentonite) is in the range of 2 to 25 wt% (No. 4 to 7), the crushing strength is much better than when the content is less than 2% (No. 1.2). Yes, and if the content exceeds 25% (No 3)
The moisture absorption capacity is also much better than that of .

(Example 3) In order to investigate the influence of porosity, silica gel was used as a Si source.
Honeycomb-shaped and linear dehumidifying materials with various degrees of porosity were produced using kaolinite as a binder and using the method described above.

The moisture absorption ability of the obtained dehumidifying material was tested under the conditions of Example 2, and the results are shown in Table 3.

As is clear from Table 3, the porosity is 0.2c c /
Nos., 1, and 2, which do not look like H, have reduced hygroscopic ability, but No. 0, 2 cc/g or more.

3.4 and 5.6 have even better moisture absorption.

In the above examples, the contents of 5iC)+, binder, and chloride are all wt% when the dehumidifying material is dried at 110° C. for 24 hours.

[Effects of the Invention] Since the present invention is configured as described above, it has excellent dehumidifying ability,
A dry dehumidifying material with less chloride elution can be provided.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between SiO2 content and moisture absorption. Figure t52 is a conceptual diagram showing a state in which a honeycomb structured test specimen is compressed. Figure 1 Figure 2

Claims (10)

[Claims] (1) A dry dehumidifier characterized by containing a Si source of 75 wt% or more in terms of SiO_2, or containing a Si source of 30 wt% or more in terms of SiO_2 and 5 to 40 wt% of chloride. (2) The dry dehumidifying material according to claim (1), wherein the chloride content is 5 to 25 wt%. (3) Claim No. 1 in which the chloride is lithium chloride (
The dry dehumidifying material according to either item 1) or item (2). (4) The dry dehumidifying material according to any one of claims (1) to (3), which contains 2 to 25 wt% of a binder. (5) The dry dehumidifying material according to any one of claims (1) to (4), which has a porosity of 0.2 cc/g or more. (6) The dry dehumidifying material according to any one of claims (1) to (5), wherein the dry dehumidifying material is in the form of an aggregate of linear extrudates. (7) The dry dehumidifier according to any one of claims (1) to (6), wherein the dry dehumidifier has a honeycomb shape. (8) The method according to any one of claims (1) to (7), wherein net-like or honeycomb-like strength reinforcing members are provided in substantially close contact with both end faces of the dry dehumidifying material in the fluid passage direction. Dry dehumidifier. (9) Claims (1) to (2) in which both end faces of the dry dehumidifying material in the fluid passage direction are impregnated with resin to strengthen the strength.
8) The dry dehumidifying material described in any of paragraphs 8). (10) Claim No. 1, wherein the binder is an inorganic binder (
The dry dehumidifying material according to any one of items 1) to (9).