JPS59160518A - Package for dehumidification - Google Patents

Abstract

PURPOSE:To provide a package which permits identification at a glance of whether the package has still the dehumidifying power or not by placing a reversible humidity detecting sheet on a part on the surface of a steam permeable sheet forming a case for sealing a hygroscopic compsn. and shielding the same from the outdoor air by a transparent film. CONSTITUTION:A hydroscopic compsn. 2 formed by impregnating a deliquescent salt such as CaCl2 in a water retaining material such as vermiculite expanded by calcination is sealed in a case consisting of a steam permeable and water impermeable sheet 1. A reversible humidity detecting sheet 3 formed by impregnaging an aq. soln. of a cobalt salt or the like on a water absorptive sheet and drying the same is placed on the surface of the sheet 1 and a transparent sheet 4 is superposed thereon. The circumference is adhered by an adhesive agent 5 to shield the sheet 3 from the external world. When such package for dehumidification absorbs moisture up to its service limit, the sheet 3 colors blue, thus indicating the service limit.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dehumidifying package that absorbs moisture from a gas such as air. It is a dehumidifying package that can be determined at a glance, and is made by covering a hygroscopic composition consisting of deliquescent salts and a water-retentive substance with a sheet that is permeable to water vapor but not water or aqueous solutions. A reversible humidity sensing sheet that detects humidity by color is placed on a part of the surface of the sheet, and a moisture vapor impermeable sheet is placed on the outside of the humidity sensing sheet. A dehumidification package equipped with a reversible wet detection sheet, which is provided with a sheet or film that is transparent and allows the change in color of the humidity detection sheet on the inside to be seen through, and isolates the humidity detection sheet from the outside air. It is a thing.

The hygroscopic composition used in the present invention is composed of deliquescent salts and water-retentive substances, and the deliquescent salts include, for example, lithium chloride, calcium chloride, magnesium chloride,
Examples include strontium chloride, barium thiocyanate, and magnesium iodide, but calcium chloride and magnesium chloride are preferred from the viewpoint of hygroscopicity, safety, and economy in a high-humidity atmosphere.

In the present invention, for example, sawdust, activated carbon, or zeolite can be used as the water-retaining substance, but expanded vermiculite and expanded gillite, which have a much higher water-retaining capacity, are particularly preferred.

In order to form a hygroscopic composition from a deliquescent salt and a water-retaining substance, a preferred method is to impregnate the water-retaining substance with an aqueous solution in which the two solids are mechanically mixed together, and then remove water by heating. In addition, glue-forming substances such as carboxymethyl cellulose or guar gum can also be present in these hygroscopic compositions.

Next, the sheet used in the present invention, which is permeable to water vapor but not permeable to water or an aqueous solution, will be explained.

Is this sheet Suno J? It is a continuous microporous sheet or film manufactured by a pumping or elution method, and examples of the former include "Tyvek" by DuPont and "Celpore" by Tanemizu Chemical Industry ■1), and specific examples of the latter. An example of this is "NFR Sheet" by Tokuyama Soda ■. These sheets can be used alone or in combination with ordinary breathable films, breathable nonwoven fabrics, paper, cloth, or threads to enhance mechanical strength or to improve beauty.

These sheets are used for the whole or part of a box-shaped or bag-shaped container.

The reversible wet-sensing sheet used in the present invention is a sheet obtained by impregnating a water-absorbing sheet, such as a filter paper, with an aqueous solution containing cobalt salts as a main component and drying the sheet. As is well known, cobalt salts exhibit a blue color when dry and a pink color when absorbing moisture. Therefore, the filter paper prepared as described above, which supports cobalt salts in its structure, has a mauve color that is a mixture of blue and pink depending on the degree of moisture absorption. According to this principle, it is possible to make a detection paper that, when left in a predetermined humid environment, exhibits a mauve color that indicates the humidity of the environment. Such a detection sheet is made to appear mauve in a humid environment, which is the limit of the moisture absorption ability of the dehumidifying composition, and is made to be transparent to water vapor containing the dehumidifying composition, but not to water or an aqueous solution. If the dehumidifying composition is placed on the surface of a bag made of a plastic sheet and its outside is isolated from the outside world by a film through which the change in color of the detection paper can be seen, the detection sheet will remain blue while the dehumidifying composition has the ability to absorb moisture. However, if the dehumidifying composition absorbs moisture from the outside world to the limit of its moisture absorption capacity, the detection paper will turn mauve. At this stage, if this dehumidifying package is placed in a dry environment, the dehumidifying composition in the package will release its moisture, and as a result, the detection paper will return to its blue color.1゜Dehumidifying package of the present invention The humidity sensing sheet installed in
If two types of detection sheets, one that exhibits mauve color at 5% relative humidity and another that exhibits mauve color at 65 degrees relative humidity, are used together, if the latter detection sheet becomes mauve, the dehumidification packaging being used will be removed. This indicates that the moisture absorption capacity of the object is approaching its limit (a condition requiring attention), and the former detection sheet turning mauve indicates that the dehumidifying package needs to be replaced with a new one. I understand.

In the present invention, the water vapor impermeable sheet or film covering the humidity indicator may be a single film such as polyvinylidene chloride, biaxially oriented polypropylene, moisture-proof cellophane, or vinylidene chloride/polypropylene, vinylidene chloride/stretched nylon or vinylidene chloride/ Examples include, but are not limited to, composite membranes such as polyester. These sheets or films do not necessarily have to be completely transparent, so long as the color change of the humidity indicator underneath can be observed through them.

The dehumidifying package of the present invention may be used as it is by placing it in the place where dehumidification is to be performed, but it may also be used in a container that is ventilated with the outside, such as a net shape, an open box shape, or a cage shape. It is convenient to store and use the container, and in this case, it is preferable to configure the container so that the color of the humidity detection sheet can be observed from the outside of the container.

Example 1 100 g of a hygroscopic composition was prepared by impregnating 1 part of calcined expanded vermiculite with 2 parts of a 50% calcium chloride aqueous solution and drying it at 170°C. A bag (10
A dehumidifying bag was manufactured by adhering and sealing it in a bag (0 tan x 130 mm) with a heat-treated adhesive. This dehumidification bag has the capacity to absorb approximately 150 tons of moisture.

As shown in Figure 1, a circular reversible humidity sensing sheet (3) with a diameter of 20III+ (a commercially available product made to turn mauve at 85% relative humidity) is placed on the bag, and the sensing sheet is placed on top of it. A larger transparent sheet (4) of polyvinylidene chloride was overlapped and its periphery was adhered to the NFR sheet of the bag with an adhesive (5) to isolate the detection sheet from the outside world. When the dehumidification package with the humidity detection sheet attached was installed in a high humidity space, the detection sheet turned blue after 5 days. At this time, the dehumidification package is 1482
The average humidity of the hygroscopic composition in the bag was measured with a hygrometer AH-1 manufactured by Shibaura Denshi Co., Ltd., and the result was 83%1. This indicates that the humidity detection sheet used here was colored blue, which faithfully indicates that the dehumidification package has absorbed moisture close to its practical limit. Ta.

[Brief explanation of the drawing]

FIGS. 10) and 1(b) are a plan view and a cross-sectional view, respectively, showing how the dehumidifying package of the present invention is used. 1: Water vapor permeable water impermeable sheet 2: Hygroscopic composition 3: Reversible humidity sensing sheet 4: Water vapor impermeable transparent film 5: Adhesive 6: Heat treatment adhesive patent applicant Agent for Nippon Sokako Co., Ltd. People Haruno Ito Yoshimi Yokoyama Figure 1

Claims (1)

[Claims] 1. A hygroscopic composition comprising deliquescent salts and a water-retaining substance, and a part or all of its surface is made of a sheet that is permeable to water vapor but not permeable to water or an aqueous solution. A reversible humidity sensing sheet that detects humidity by color is placed on a part of the surface of the container, and the color of the inner humidity sensing sheet that is impermeable to water vapor is placed on the outside of the humidity sensing sheet. 1. A dehumidifying package comprising a reversible humidity sensing sheet, the humidity sensing sheet being isolated from the outside air by providing a sheet material or film through which changes in humidity can be seen. 2. The dehumidifying package according to claim 1, wherein the deliquescent salt is calcium chloride or/and magnesium chloride. 3. Claim 1, wherein the water-retaining substance is expanded vermiculite and/or expanded pearlite.
The dehumidifying package according to item 1 or 2. 4. Claim 1 in which the container is bag-shaped
Item 2 or 'fc' refers to the dehumidifying package described in Item 3.