GB2161093A - Dehumidifier package - Google Patents

Abstract

A moisture absorbent package is disclosed. This package consists of two side walls and an inwardly bent bottom member. Each of the side walls is made of a material which is impermeable to both air and water and is heat-sealable on the inner surface. One side wall is provided with a horizontal cut running generally across the center so that the upper half of the wall is peelable and the lower half remains intact as part of the package. A water-impermeable but air- permeable film is lying under the peelable half of said one side wall in such a manner that said film extends downwardly to partly overlap the lower half of the side wall. An another embodiment inner and outer bags each have an air- permeable but water-impermeable area the two areas facing one another. <IMAGE>

Description

SPECIFICATION Dehumidifier package The present invention relates to a package for an aerial moisture absorbent that normally remains air-tight and enables moisture absorption as required. The invention also relates to a dual package that consists of inner and outer bags which allow the function of the moisture absorbent to be effective throughout its period of use.

Modern Japanese houses feature a higher degree of insulation of air in the interior from the outside than the old "wood and paper" houses, but on the other hand, this offers favorable conditions for mold growth in various home furniture and fittings such as wardrobes, cupboards, shoe cabinets, bookcases and closets. In order to prevent any mold growth in these places, moisture absorbents such as silica gel and calcium chloride that are put in bags and other containers are often used.

Particularly, calcium chloride is often used because of its high hygroscopicity and cheapness.

A conventional moisture absorbent package is shown in Fig. 1-a; the moisture absorbent a is put in an inner bag b made of an air- and water-permeable material. In this type, silica gel is commonly used as a absorbent, which is sealed in an outer bag c made of an air-impermeable material. One disadvantage with this dual bag is that the outer bag c must be torn open so that the inner bag b can be taken out so as to allow the moisture absorbent a to exhibit its function.

Another problem is that if calcium chloride having high hygroscopicity is used as the moisture absorbent, it gradually dissolves and becomes liquid by absorbing moisture, producing dew drops that drip from the surface of the inner bag b. Calcium chloride is highly deliquescent and changes from solid to liquid as it absorbs moisture, and the water absorption continues until the equilibrium is reached.

An improved version of this conventional moisture absorbent package is shown in Fig. 1-b; the moisture absorbent a is put in a bag dwhich is made of a lamination of an inner layer fand an outer layer g that are sealed on the periphery A. The inner layer f consists of an airimpermeable material e and an air-permeable material such as nonwoven cloth. The outer layer g consists of an air-impermeable material. The adhesion between the inner layer fand the outer layer g is so controlled that the latter is easily peelable from the former. However, even this improved package is not entirely free from the possibility that the moisture absorbed will condense and ooze out of the bag.

A plastic molding of the type shown in Fig. 2 is also used as a moixture absorbent container.

The container generally indicated at din Fig. 2 has ventilators fin the side wall of the uper lid e and the moisture absorbent is placed within this container. This molded container is sealed within an air-impermeable material which must be torn open just before use. In addition to this inconvenience in handling, the plastic container is fairly expensive because of the cost of molding.

One object, therefore, of the present invention is to provide an inexpensive and easy-to-handle moisture absorbent bag.

Another object of the invention is to provide a dual package for moisture absorbent that ensures efficient moisture absorption throughout the period of use without any leak of water from the package.

Figure 1 shows in cross section two conventional packages for moisture absorbent; Figure 2 is a perspective view of a conventional plastic container for moisture absorbent; Figure 3 is a front view of the moisture absorbent package in accordance with one embodiment of the present invention; Figure 4 is a cross section taken on line V-V of Fig. 3; Figure 5 is a longitudinal section of the dual package in accordance with another embodiment of the present invention; Figure 6 is a plan view of the inner bag of the package shown in Fig. 5; Figure 7 is a longitudinal section of the inner bag of the package shown in Fig. 5; Figure 8 is a longitudinal section of the outer bag of the package shown in Fig. 5; Figure 9 is a front view of a modification of the dual package in accordance with the present invention; and Figure 10 is a longitudinal section taken on line VI-VI of Fig. 9.

The moisture absorbent package in accordance with one embodiment of the present invention consists of two side walls and an inwardly bent bottom member. The two side walls are made of a material which is impermeable to both air and water and is heat-sealable on the inner surface.

One side wall is provided with a horizontal cut running generally across the center so that the upper half of the wall is peelable and the lower half remains intact as part of the package. Lying under the peelable half of the side wall is a water-impermeable but air-permeable film that extends downwardly to partly overlap the lower half of the side wall. In a preferred embodiment, a seal having a great adhesive strength is provided between the two side walls, in the area of contact between each side wall and the bottom member, and in the area of contact between the lower half of one side wall and the overlapping air-permeable film, whereas a seal with a smaller adhesive strength is provided between the peelable portion of said one side wall and the underlying air-permeable film.One advantage with this preferred embodiment is its great ease in handling because the peelable half of one side wall can be easily pulled off so as to expose the underlying air-permeable film through which moisture can be absorbed from the atmosphere.

In accordance with another embodiment of the invention, there is provided a moisture absorbent package that is composed of an outer bag and a smaller inner bag, each having an air-permeable but water-impermeable portion, with the air-permeable but water-impremeable portion of the outer bag being placed in a face-to-face relation with the corresponding part of the inner bag. The moisture absorbent, calcium chloride, is placed within the inner bag. Even if a pinhole or rupture occurs in that part of the outer bag, no water will flow out of the waterimpermeable inner bag unless a pinhole also occurs in the inner bag.

One might suspect that the package with the dual structure would have a slower absorption rate. But by using an inner bag made of a film that has an air permeability of 1-200 seconds/100 ml, preferably 1-20 seconds/100 ml as measured by type B Gurley densometer, a moisture absorption rate is achieved that is comparable to the value obtained in the absence of the inner bag. Additionally, the water absorbed from the atmosphere builds up on the bottom of the inner bag, and a fairly large effective area is provided for the moisture absorbent this ensuring consistently efficient absorption throughout the period of use.

The moisture absorbent package in accordance with the present invention is hereunder described in detail by reference to Figs. 3 to 10.

The device shown in Figs. 3 and 4 is of the type generally referred to as a standing pouch. It consists of two side walls 1, 2 and an inwardly bent bottom member 3. The two side walls are made of a material which is impermeable to both air and water and is heat-sealable on the inner surface. One side wall 2 is provided with a horizontal cut 4 running generaly across the center so that the upper half 5 of the wall is peelable and the lower half 6 remains intact as part of the package. Lying under the peelable half 5 of the side wall is a water-impermeable but airpermeable film 7 that extends downwardly to partly overlap the lower half 6 of the side wall.

Seal A is provided between the two side walls 1, 2, in the area of contact between each side wall and the bottom member 3, and in the area of contact between the side wall 2 and the overlapping air-permeable film 7. Moisture absorbent 8 is hermetically sealed within the resulting package.

Preferably, the seal A consists of two portions having different degrees of adhesive strength.

That is, the seal provided between the air-permeable film 7 and the peelable portion 5 is weak whereas the seal provided between the lower half 6 and the overlapping air-permeable film 7 is as strong as the seals between the side walls and between each side and the bottom member 3.

The design permits greater ease in peeling the upper half 5 of the side wall 2 from the underlying air-permeable film 7 as required.

The film 7 may be made of a variety of materials that are impermeable to water but permeable to air. Foraminous plastic films having a great number of micro pores (0.02-4.0 #m in size) may advantageously be used. The reason why water is impermeable to such films is that the absorbed water in a bag cannot pass through the micro pores because the sizes of water particles are larger than those of the pores. On the other hand, the sizes of the particles of water vapor are smaller than those of the pores. Thus, the water vapor can freely pass through such films. Such foraminous plastic films may be formed from various materials such as polypropylene, high-density polyethylene and polyesters.

The perforation ratio (the percent ratio of the total surface areas of pores to that of the film) of such foraminous materials is generally at least 20%, preferably at least 30%. The film has a Gurley air permeability of ca. 100-250 seconds/100 ml. The water-impermeable and airpermeable films may bve entirely or partly laminated with a heat-sealable resin layer to the extent that the latter will not impair the air-permeability of such films. Alternatively, the film 7 may be prepared by coating, for example, polypropylene on the outer surface of a non-woven fabric made from such synthetic resin fibers as polypropylene, polyethylene and nylon.

The other side wall 1 and the bottom member 3 may be made of any material that is impermeable to both air and water and has heat sealability. Typical examples include synthetic resin films such as polyethylene and polypropylene, as well as laminations of themselves and combinations with metal foils. An example is a triple lamination consisting of cellophane, aluminum foil and polyethylene, this being commonly used as the material for standing pouches.

The package described above provides great convenience in handling because it normally remains air-tight and, if necessary, can readily provide air-permeability if the peelable portion of one side wall is merely pulled off. Additionally, the package which is in a bag form can stand by itself, and even if it should fall down, the absorbed moisture or the absorbent 8 (e.g. calcium chloride) that has become liquid as a result of moisture absorption will not leak out of the package. Before filling with the absorbent, the package can be folded into a flat form. The package in accordance with the present invention therefore has great advantages with regard to transportation, storage, production and handling.

The package described above may be so designed that the area of the peelable portion is variable by, for example, providing a plurality of cuts. The user may select the desired absorption period.(i.e., the period for which the absorbent exhibits its function) by pulling off a suitable area in the peelable portion.

Compared with the conventional molded plastic container, the package in accordance with the present invention is compact and can be manufactured at low cost. If desired, a hole may be punched in the upper part of the package so that it can be freely suspended in the air by hanging it on a hook. Furthermore, one of the two side walls of the package may be made of a transparent film so that the user can readily recognize the end point of use.

Fig. 5 shows an absorbent package in accordance with another embodiment of the present invention wherein an inner bag containing the absorbent has an outer bag wrapped around it.

Figs. 6 and 7 show the construction of the inner bag, and Fig. 8 shows the construction of the outer bag.

The outer bag generally indicated at 51 is of the standing pouch type; it consists of two side walls 2, 1 and an inwardly bent bottom member 3. The two side walls are made of a material which is impermeable to both air and water and is heat-sealable on the inner surface. A film 7 that is made of an air-permeable but water-impermeable material is provided to overlap the upper end of one side wall 2. A peelable portion 5 made of a film that is impermeable to both water and air is bonded to the outer surface of the air-permeable film 7 so that no moisture will be absorbed from the air while the package is not in use.

Seal A is provided between the two side walls 2, 1, in the area of contact between each side wall and the bottom member 3, and in the area of contact between the air-permeable sheet 7 and one side wall 2. Moisture absorbent 8 is hermetically sealed within the resulting outer bag 51.

Preferably, the seal A consists of two portions having different degrees of adhesive strength, as in the case of the package shown in Fig. 3. That is, the seal provided between the airpermeable film 7 and the peelable portion 5 is weak whereas the seal provided between the airpermeable sheet 7 and the side wall 2 is as strong as the seals between the side walls and between each side wall and the bottom member 3. This design permits greater ease in pulling off the peelable portion 5 from the underlying air-permeable film 7 as required.

The inner bag generally indicated at 50 consists of two side walls 11, 12 bonded together by seal A. The side wall 11 is made of a film which is impermeable to both air and water, and the other side wall 12 is made of an air-permeable and water-impermeable film. Moisture absorbent 8 is placed within the inner bag. The inner bag 50 is then placed within the outer bag 51, preferably in such a manner that the air-permeable side 12 faces the air-permeable film portion 7 of the outer bag 51.

The package described above remains air-tight until use, and can be put to use by simply pulling off the peelable portion 5 so that moisture can be absorbed from the air through the airpermeable film 12 of the inner bag 50 and the air-permeable film 7 of the outer bag 51.

Figs. 9 and 10 show a modified form of the package having the construction illustrated in Fig. 5. The inner bag generally indicated at 50 may have the same construction as shown in Fig. 5. One side wall 2 of the outer bag 51 is provided with a horizontal cut 4 running generally across the center so that the upper half 5 of the wall is peelable and the lower half 6 remains intact as part of the package. Lying under the peelable half 5 of the side wall is a waterimpermeable but air-permeable film 7 that extends downwardly to partly overlap the lower half 6 of the side wall 2.

One side wall 12 of the inner bag 50 may be made of a variety of materials that are impermeable to water but permeable to air. Foraminous plastic films having a great number of micro pores may advantageously be used. The pore size is preferably 5-10 lim. Such films has preferably a Gurley air permeability of ca. 1-200 seconds/100 ml. The perforation ratio of such foraminous materials is preferably at least 20%. Such foraminous plastic films may be of the same type as those used for the air-permeable sheet 7 of the outer bag 51. From an absorption rate viewpoint, a foraminous polyethylene or polypropylene film laminated with one or two layers of non-woven fabric is preferred.

The other side wall 11 of the inner bag 50 is preferably made of the same material as is used for the side walls 2, 1 and the bottom member 3 of the outer bag 51. In order to ensure convenience in the manufacture and use of the moisture absorbent, a thick film is desirably used as the material of the side wall 11.

As described above, the moisture absorbent package in accordance with the second and third embodiments of the present invention has a dual structure consisting of an inner bag that is composed of an air- and water-impermeable film for retaining the moisture absorbent and part of which is made of an air-permeable but water-impermeable film, and an outer bag that is generally composed of an air- and water-impermeable film and at least one side wall of which is provided with an air-permeable area that is formed of an air-permeable but water-impermeable film. Because of this design, even if a pinhole occurs in that area of the outer bag, the absorbed water will build up in the inner bag and will not leak to the outside.

The air-permeable film which is used in part of the inner bag has proved to achieve a moisture absorption rate that is comparable to the value obtained in the absence of such inner bag if that air-permeable film has a Gurley air permeability of ca. 1-20 seconds/ 100 ml. Thus, the package in acordance with the present invention ensures effective absorption of moisture from the air throughout the period of use.

Examples 1 to 6 An inner bag having the construction shown in Fig. 7 was prepared. A foraminous film having an air permeability of ca. 1 second/ 100 ml was superimposed on a film composed of a nylon film (15 #m) that has been laminated onto a polyethylene film (120 m). The three sides of the sheet assembly were sealed to make an inner bag 110 mm wide and 170 mm high (inside dimensions: 105 X 165 mm).

Five other inner bags were prepared by the same procedures, except that the air permeability of the foraminous film was changed to be ca. 5, 20, 50, 100 and 200 seconds/100 ml.

An air-permeable (ca. 200 seconds/100 ml) but water-impermeable foraminous film was combined with an air- and water-impermeable polymeric film to make an outer bag with an open top having inside dimensions of 115 mm and 210 mm.

A metered amount (200 g) of calcium chloride was put into the inner bag as a moisture absorbent. After heat-sealing the open end, the inner bag was placed in the outer bag and its open top was heat-sealed. By this procedure, packaged moisture absorbent sample Nos. 1 to 6 having the construction shown in Fig. 5 were prepared.

A control sample was prepared by directly putting 200 g of calcium chloride into the outer bag and heat-sealing its open top.

Sample Nos. 1 to 6 and the control were placed in a humidistat (25 C X 75% r.h.) for varying periods, 1 day, 2 days, 6 days and 12 days. The water absorption levels for the respective storage periods are summarized in the following table.

Table

Sample pe Air permeability I Water absorption (g) No. of the inner bag (sec/100 ml) 1 day 2 days ! 6 days 12 days 1 1 1 1 10 26 1 54 1 83 2 5 9 25 ! 54 ! 83 3 20 8 24 53 1 82 4 50 1 7 ~ 10 1 27 42 5 100 6 i 8 1 24 1 39 6 1 200 4 7 16 1 29 Control I no inner bag i, 10 1 26 , 53 . 83 The above data show that sample Nos. 1 to 3 which were provided on one side of the inner bag with air-permeable films having air permeabilities of 1-20 seconds/100 ml exhibited an absorption capacity comparable to that of the control. On the other hand, sample Nos. 4 to 6 with air permeabilities lower than 20 seconds/ 100 ml had a smaller absorption capacity. It should be noted that an inner bag using an air-permeable film with a fairly high air permeability (ca. 1 second/100 ml) may cause water leakage if it is subjected to pressure after absorbing moisture from the air.

Claims (8)

1. A moisture absorbent package comprising two side walls and an inwardly bent bottom member, each of the side walls being made of a material which is impermeable to both air and water and is heat-sealable on the inner surface, one side wall being provided with a transverse cut so that an upper portion of the wall is peelable and a lower portion remains intact as part of the package, a water-impermeable but air-permeable film lying under the peelable portion of said one side wall in such a manner that said film extends downwardly to partly overlap the lower portion of the side wall.

2. A moisture absorbent package according to Claim 1 wherein a seal having a great adhesive strength is provided between the two side walls, in the area of contact between each side wall and the bottom member, and in the area of contact between the lower portion of one side wall and the overlapping air-permeable film, whereas a seal with a smaller adhesive strength is provided between the peelable portion of said one side wall and the underlying airpermeable film.

3. A moisture absorbent package according to Claim 1 or Claim 2 wherein said transverse cut runs horizontally across the centre of one side wall so that the upper half of the wall is peelable and the lower half remains in tact.

4. A moisture absorbent package with a dual structure consisting of outer and inner bags each having an air-permeable but water-impermeable area, the air-permeable but waterpermeable area of the outer bag being placed in face-to-face relation with the corresponding area of the inner bag.

5. A moisture absorbent package according to Claim 4 wherein the air-permeable but waterimpermeable area of the inner bag is composed of an air-permeable but water-impermeable film having a multitude of micro pores or a lamination of such film with one or two layers of nonwoven fabric.

6. A moisture absorbent package according to Claim 5 wherein the air-permeable but waterimpermeable area of the inner bag has micro pores of 5-10,um in size, a perforation ratio of at least 20% and an air permeability of 1-200 seconds/100 ml.

7. A moisture absorbent package according to Claim 6 wherein said air permeability ranges from 1 to 20 seconds/100 ml.

8. A moisture absorbent package according to any one of Claims 4 to 6 wherein the airpermeable but water-impermeable area of the outer bag has micro pores of 1-4,um in size, a void volume of at least 20% and an air permeability of 100-250 seconds/100 ml.