STORAGE RECEPTACLE

Abstract: A storage receptacle provided with a receptacle body opened on its upper side, a covering member for covering the opening portion of the receptacle body and a permeable film member having a permeability to gases and a moisture permeability from 1500 to 3500 g/m².24hr and formed at least on a portion of the receptacle body or covering member.

Description: BACKGROUND OF THE INVENTION The present invention generally relates to a container for storage and more particularly, to a storage receptacle for storing therein vegetables in a fresh condition, with the storage receptacle being accommodated in a chilled room such as in a refrigerator or the like Conventionally, when vegetables are requested to be stored in a fresh condition for a long time, they are initially put into a storage receptacle and the storage receptacle storing therein the vegetables is, then, accommodated in a refrigerator, while it is hermetically covered with increased air-tightness to prevent the vegetables from being dried or withered. By the above described construction, however, since the storage receptacle is of a completely sealed construction, moisture vaporized from the vegetables, particularly leafy vegetables, forms dew on the inner surface of a cover which covers an opening defined on the upper side of the receptacle and as a result, a large amount of dew tends to adhere thereon. This is because a temperature difference is produced between opposite faces of the cover. The temperature difference results from the fact that the storage receptacle for storing therein the vegetables is generally located at the bottom of a coldroom and the external surface of the cover is, therefore, cooled by cold air within the coldroom, while the inside of the storage receptacle is relatively high in temperature on account of breathing heat of the vegetables. The large amount of dew caused to adhere to the inner surface of the cover drops spontaneously or due to some vibration or the like in case of taking in and out of the storage receptacle followed by opening and shutting of the cover, and consequently, the dew stays on the surfaces of the vegetables stored or collects at the bottom of the storage receptacle. Accordingly, although the vegetables are kept in the fresh condition for a first few days from the initial storage thereof due to the fact that the vegetables are prevented from being dried during this period, they are damaged before long by the collecting water, thus resulting in a problem such that the vegetables become bad. It has been, therefore, difficult to store the vegetables in the fresh condition for a long time. In particular, in the case where fresh vegetables, particularly leafy vegetables, are additionally put into the storage receptacle storing therein other ones for a few days, there has been a problem such that the vegetables previously stored are rapidly damaged or spoiled by the moisture vaporized from the fresh vegetables. A further storage receptacle is known from FR-A-2517279. In this prior art receptacle, vegetables, etc. are stored within a chamber defined by a plurality of partition plates, which are provided with a plurality of openings and are spaced from the walls of the receptacle. Water vapor can permeate through the openings of the partition plates, but condenses inside the receptacle and accumulates at the bottom thereof. Accordingly, there is only a little difference in water vapor density between the inside and the outside of the partition plates. In order to make excess water vapor contained within the chamber fully permeate through the partition plates to get out of the chamber, it is necessary to considerably widen the distance between the inner walls of the receptacle and the partition plates. In such a case, however, the receptacle becomes very large for its storage capacity. Furthermore, since water accumulates at the bottom of the receptacle, the disadvantage is that germs can be propagated and the bottom of the receptacle may become musty. If the receptacle falls down and its cover is opened, water accumulated in the receptacle may spill. DE-A-21 04 796 discloses a corrugated box provided with an internal cover having a plurality of openings. The walls and the cover of this prior art box consist of corrugated card board which forms the core of the walls and the cover and is covered on its opposite sides each by a polyethylene film. The main purpose of this polyethylene film is to make the corrugated card board waterproof, to increase its stability and to reduce its water-permeability. Most of the water vapor gets out of the corrugated box through the openings of the cover. However, the provision of such openings has the disadvantage that pollutions can enter the box from outside. SUMMARY OF THE INVENTION Accordingly, the present invention has been developed with a view to substantially eliminating the above described disadvantages inherent in the prior art storage receptacle, and has for its essential object to provide an improved storage receptacle which is capable of storing therein vegetables in a fresh condition for a long time, with a humidity inside the storage receptacle being kept in a range most suitable for the storage of the vegetables by restricting moisture condensation on a cover of the storage receptacle. Another important object of the present invention is to provide a storage receptacle of the above described type which suits best to the storage within a refrigerator. A further object of the present invention is to provide a storage receptacle of the above described type which is capable of preventing bacteria or funguses from propagating. These objects and further advantages are accomplished by a storage receptacle comprising: a receptacle body open on its upper side; a cover member for covering the opening portion of said receptacle body; and a permeable film member having a permeability to gases and to moisture and formed at least on a portion of said receptacle body and/or said cover member; characterized in that said permeable film member covers a plurality of openings formed at least in said portion of said receptacle body and/or in said cover member and that said permeable film member is a laminated member comprising fibrous layers formed on opposite sides of a permeable thin resin layer. In the storage receptacle according to the present invention, excess water vapor contained in the receptacle can permeate through the openings and the permeable film member covering the openings, because of the great difference in water vapor density between the inside and the outside of the receptacle. Accordingly, the water vapor does not condense in the receptacle nor accumulate at the bottom thereof. Since the openings are covered by the permeable film member, pollutions cannot enter the receptacle from outside. The couple of fibrous layers formed on opposite sides of a permeable resin thin layer provides the film member with the required stability. Such a laminated construction of the permeable film member is advantageous since the thickness of the permeable thin resin layer can be selected in accordance to the required permeability without decreasing the stability of the whole film member. The subclaims define advantageous embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will become apparent from the following description taken in conjunction with the preferred embodiments thereof with reference to the accompanying drawings, throughout which like parts ere designated by like reference numerals, and in which: Fig. 1 is a perspective view of a storage receptacle according to a first embodiment of the present invention; Fig. 2 is a vertical sectional view of the storage receptacle of Fig. 1; Fig. 3 is an enlarged fragmentary section of a cover shown in Fig 2; Fig. 4 is a vertical sectional view of a refrigerator accommodating therein the storage receptacle of Fig 1; Fig. 5 is a graph showing a change of humidity inside the storage receptacle with time in a cold storage as shown in Fig. 4; Fig. 6 is a view similar to Fig. 1 according to a second embodiment of the present invention; Fig. 7 is a view similar to Fig 4, in which the storage receptacle according to a third embodiment of the present invention is accommodated in the refrigerator; Fig. 8 is an enlarged fragmentary vertical sectional view of a main portion of the storage receptacle of Fig. 7; Fig. 9 is a perspective view of the cover of the storage receptacle of Fig. 7; Fig. 10 is an enlarged fragmentary sectional view of the cover of Fig. 8 for showing an operation thereof; and Fig. 11 is an enlarged fragmentary sectional view of a main portion of the cover of the storage receptacle according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, a hermetically covered storage receptacle of the present invention will be explained hereinbelow according to preferred embodiments thereof. There is shown in Fig. 1 and 2, the hermetically covered storage receptacle 1 of the present invention having a receptacle body 2 opened on its upper side and a cover 3 for covering the receptacle body 2. The cover 3 substantially in the form of a plate is provided with a plurality of latticed openings 4 defined therein and a permeable film 5 which is bonded on the inner surface of the cover 3 by a bonding material or the like so as to cover the latticed openings 4. The peripheral portion 6 of the cover 3 is shaped, in cross section, substantially in the form of an inverted figure "U" and is closely engaged with the peripheral edge portion 7 of the receptacle body 2 for complete seal of the storage receptacle 1. Both the receptacle body 2 and the cover 3 are molded products of synthetic resin having superior fitability for air tightness, such as polyethylene, polypropylene or the like. Hereupon, with reference to Fig. 3, the permeable film 5 will be explained in detail hereinafter. The permeable film 5 is a laminated member composed of a base cloth 5a of a fibrous layer such as polyester, nylon or the like, a silicone resin thin film 5b having a thickness from microns to several tens of microns and integrally formed on the base cloth 5a, and a protective fibrous layer 5c formed on the silicone resin thin film to protect it from being broken. The permeable film 5 is regulated in moisture permeability from 1500 to 3500 g/m²·24hr. The regulation of the moisture permeability is primarily achieved by changing the thickness of the silicone resin thin film 5b. More specifically, the silicone resin thin film 5b is substantially composed of a chain molecule aggregate of amorphous and the linearly formed molecule aggregate completely shuts out a liquid. The silicone resin thin film 5b, however, has a permeability to gases through molecule intervals of 10 to 10³ Å and permits water moisture, air, carbon dioxide gas or the like to permeate therethrough, if there exists a concentration difference between opposite sides thereof. Furthermore, the moisture permeability can be also more or less regulated by changing the thickness or weave pattern of the base cloth 5a or the protective fibrous layer 5c. The aforementioned value of the moisture permeability is a value measured in accordance with a method of testing moisture permeability of moisture-proof packaging material based on JIS (Japanese Industrial Standard). The reason why the moisture permeability of the permeable film 5 is regulated in the range of the above described numerical values resides in a discovery such that the exists a desirable balance between an effect of preventing the moisture condensation on the wall surface of the storage receptacle 1 and another effect of preventing the food, for example, the vegetables 8 or the like from being dried, as a result of repeated experiments which have been performed in a manner that upon containment of food having a large moisture content such as vegetables 8 or the like within the storage receptacle 1, the food accommodated within the storage receptacle 1 is stored in the atmosphere at a temperature from 0 to 30°C. Moreover, an area required for the permeable film 5 to be used depends upon a volume of the hermetically covered storage receptacle 1 and the kind of food to be accommodated therein. For example, in the case where the storage receptacle 1 is used as a receptacle for storing therein the leafy vegetables such as spinach or the like, the permeable film 5 having the area of approximately 0.1 m² is used for each 50 liters of volume of the sealed storage receptacle 1 according to the experimental result. Fig. 4 illustrates a state where the storage receptacle 1 storing therein the vegetables 8 is accommodated in a coldroom of the refrigerator. The refrigerator has a refrigerator body 11 composed of an external box 12, an internal box 13 and a foamed heat-insulating material 14 filled between both boxes 12 and 13. There are provided a compressor 15 disposed outside the bottom of the refrigerator body 11 to compress a refrigeration medium and a condenser 16 disposed inside a back plate of the external box 12 to condense the refrigeration medium compressed by the compressor 15. The inside of the internal box 13 is partitioned into a freezer 18 and a coldroom 19 by a partition wall 17 and there are provided inside the partition wall 17, an evaporator 20 for evaporating the refrigeration medium condensed in the condenser 16 and a fan 21 for ventilating the cold air cooled down by the evaporator 20 back to the inside of the refrigerator 11. The storage receptacle 1 of the present invention is provided on a shelf 22 disposed inside the coldroom 19. Meanwhile, in Fig. 4, a receptacle 23 opened on its upper side and disposed at the bottom of the coldroom 19 is a conventionally known one for storing therein the vegetables or the like. By the above described construction, through operation of a refrigeration cycle including the compressor 15, condenser 16 and evaporator 20, and through rotation of the fan 21, the insides of the freezer 18 and coldroom 19 are cooled down to respective predetermined temperatures and accordingly, the storage receptacle 1 accommodated within the coldroom 19 is cooled down simultaneously. Such being the refrigerator in construction, when vaporish vegetables 8 such as spinach or the like are contained in the storage receptacle 1 sealed in appearance and kept in cold storage, the water content i.e., vapor vaporized from the vegetables 8 has primarily formed dew on the surface of the cover 3 so far. In this embodiment, however, since the vapor permeates through the permeable film 5 outside the storage receptacle 1 at an appropriate speed, as shown by arrows in Fig. 3, it is possible not only to keep the inside of the storage receptacle in a desirable high humidity of around 80 to 95% RH (Relative Humidity), but also to prevent the condensation of the vapor on the inner wall of the storage receptacle 1 including the cover 3. Accordingly, since the condensed water never drops to stay on the surfaces of the vegetables 8 or at the bottom of the storage receptacle 1, the vegetables 8 stored therein are restrained from being dried and withered and they never go bad before long through damage thereof by the condensed water. As a result, the vegetables 8, particularly the leafy vegetables such as spinach or the like, can be stored desirably for a longer period than before. Fig. 5 graphically shows a change in humidity with time within the receptacle in the case where the spinach has been kept in cold storage with the use of the storage receptacle 1 of the present invention, and teaches that the inside of the storage receptacle 1 is kept for a relatively long period in the humidity of 80 to 95% RH suitable for the storage of the vegetables. In this experiment, the volume of the storage receptacle 1 is 42 liters, the area of the opening defined in the cover 3 is 1,000 cm² and the moisture permeability of the silicone resin thin film 5b is 2,100 g/m²·24hrs. Furthermore, the case where the spinach of approximately 2 kg or 0.5 kg is accommodated within the storage receptacle 1 is respectively shown by a line A or B in Fig. 5. It is to be noted that in this embodiment, the silicone resin thin film 5b may be replaced by a thin film of polyamino acid type urethane or the like having the moisture permeability as well. It is also to be noted that the bonding of the permeable film 5 onto the cover 3 can be executed by a method of fusion-bond through a hot plate. In the next place, with reference to Fig. 6, the sealed type storage receptacle 1a according to a second embodiment of the present invention will be explained hereinbelow. Fig. 6 shows the sealed type storage receptacle 1a according to the second embodiment of the present invention, which differs from the first embodiment in that a plurality of latticed openings 9 are additionally defined in a part of a side wall of the receptacle body 2 and are covered with the permeable film 5 as well as those defined in the cover 3. This additional provision of the permeable film 5 is based on the fact that in the case where the sealed type storage receptacle 1a is placed on a shelf or the like disposed within the refrigerator of forced circulation type, the storage receptacle 1a, particularly the side wall thereof is occasionally strongly cooled down, though there is some difference according to the way of placing the storage receptacle 1a. Accordingly, the condensation which tends to arise on the inner wall of the receptacle is prevented by additionally providing the permeable film 5 on the side wall of the receptacle body 2. In this second embodiment as well as in the first embodiment, the vegetables, in particular, the leafy vegetables e.g., the spinach or the like can be stored in a fresh condition for a longer period than before. Subsequently, with reference to Figs. 7 through 10, a storage receptacle 31 for use in the refrigerator to contain therein the vegetable will be explained hereinafter according to a third embodiment of the present invention. The explanation with respect to the refrigerator will be omitted for brevity's sake, since the construction thereof in this embodiment is the same as that shown in Fig. 4. A receptacle body 32 having, on its upper side, an opening portion closely covered with a cover 33 is substantially similar in configuration to the receptacle 23 shown in Fig. 4. the cover 33 composed of olefin thermoplastic resin or the like, for example polyethylene etc., is provided with a plurality of latticed openings 34 defined therein, permeable film 35 securely fusion-bonded on one surface of the cover 33 and a packing 36 of rubber such as vinyl chloride or the like disposed on the periphery of the permeable film 35. The storage receptacle 31 for containing therein the vegetables is detachably disposed at a predetermined position inside the coldroom 19 of the refrigerator body 11 at the bottom thereof, while being tightly covered with the cover 33 having the rubber-make packing 36 at the periphery thereof. Hereupon, the aforementioned permeable film 35 will be described in detail hereinbelow. The permeable film 35 is a laminated member including a base cloth 35a of polyester weave such as polyester taffeta or polyester knit, a silicone resin thin film 35b having a thickness of several tens of microns and formed on the base cloth 35a, and a protective fibrous layer 35c composed of polyester taffeta or polyester knit and formed on the silicone resin thin film 35b to prevent the break thereof. The reason why polyester taffeta or polyester knit is employed for the base cloth 35a and the protective fibrous layer 35c is based on the fect that as a result of an experiment, either of these materials has been found out superior to other fabrics such as nylon and the like in stain resistance with respect to such food as juice, coffee, soy or the like and suitable for use in the refrigerator. The permeable film 35 is fusion-bonded, at one surface of the base cloth 35a, onto the cover 33. Although it is difficult to fusion-bond the silicone resin thin film 35b itself, which is superior in permeability, onto the cover 33, if the base cloth 35a is disposed therebetween as described above and the cover 33 is thermally pressed against the permeable film 35 to a certain extent not to damage the openings 34, the permeable film 35 can be bonded with the cover 33, since the molten polyolefin resin bites into the weave patterns of the base cloth 35a. In the case where the thermal fusion-bond is employed as a bonding means as described above, since the molten resin is liable to bite into gaps defined in the base cloth 35a of polyester knit as compared with that of polyester taffeta, the former is superior in bond strength to the latter. Such being the construction, the cold air never enters the vegetable storage receptacle 31 directly and the inside thereof is desirably kept in appropriately high humidity by the moisture vaporized from the vegetables 8 stored therein. Although the moisture exceeding the saturated humidity tends to form dew on the inner surface of the cover 33 which faces the coldroom 19 and is, therefore, cooled down to the utmost by the cold air strongly blowing thereagainst, the moisture gradually permeates through the permeable film 35 formed on the cover 33 into the coldroom 19, as shown by arrows in Fig. 10, while the inside of the coldroom 19 is kept in a dry condition by the evaporator 20 disposed within the refrigerator. Furthermore, even when some quantity of moisture condensation 37 arises at times on the cover 33 of a support member having a plurality of openings 34, as shown in Fig. 10, in the case where a large amount of the vegetables are stored in the storage receptacle 31 and a considerable amount of the moisture is vaporized, the moisture condensation vaporizes to gradually vanish. Accordingly, since the moisture condensation never drops to stay on the surface of the vegetables 8 or at the bottom of the vegetable storage receptacle 31, the vegetables 8 stored is not only restrained from being dried or withered, but also not damaged by water drops, thus resulting in that the vegetables 8, particularly the leafy vegetables such as spinach or the like, can be stored desirably in the fresh condition for a longer period than before. It is to be noted that the silicone resin thin film 35b in this embodiment may be replaced by a finely porous thin film of tetrafluoro ethylene or polyurethane having as same permeability as the former has. With reference to Fig. 11, the storage receptacle according to a fourth embodiment of the present invention will be explained hereinafter. It should be noted that since this embodiment is different from the aforementioned embodiments only in the construction of the permeable film, no entire construction of the receptacle body and the storage receptacle having the cover 43 will be shown in any drawing for brevity's sake. A permeable film 45 is a laminated member composed of a base cloth 45a of polyester, nylon or the like, a silicone resin thin film 45b having a thickness of several tens of microns and formed on the base cloth 45a, an urethane thin film 45d having a thickness of several microns and formed on the silicone resin thin film 45b, a bond layer 45e and a protective fibrous layer 45c covered on the urethane thin film 45d through the bond layer 45e to protect the break of the silicone resin thin film 45b or the urethane thin film 45d. The permeable film 45 is fusion-bonded, at one surface of the surface of the base cloth 45a, with the cover 43. Although it is difficult to fusion-bond the silicone resin thin film 45b itself onto the cover 43, if the base cloth 45a is disposed therebetween and the cover 43 is thermally pressed against the permeable film 45 to a certain extent not to damage the openings 44, the permeable film 45 can be bonded with the cover 43, since the molten polyolefin resin bites into the weave patterns of the base cloth 45a. Except the method of fusion-bonding, there exists, as the method of bonding, the bonding by a bonding agent or a method of nipping the permeable film between a couple of plate members in the form of a net. The bond layer 45e is composed of a plurality of thin bond films spaced at predetermined intervals formed on either the urethane thin film 45 d or the protective fibrous layer 45c through a processing method generally called "bonding dot process" and, the urethane thin film 45d and the protective fibrous layer 45c are bonded with each other. Hereupon, an explanation will be made hereinbelow with respect to an operation of the urethane thin film 45d. When the silicone resin thin film is directly covered, at its one surface, with the protective fibrous layer 45c, the sufficient bonding strength can not be obtained therebetween. The urethane thin film 45d is, therefore, formed as thin as possible on the silicone resin thin film 45b so as not to disturb the permeability and as a result, the bonding of the silicone resin thin film 45b with the protective fibrous layer 45c is increased in bonding strength. There is substantially no difference in function between the permeable film formed on the inner surface of the cover as shown in Fig. 3 and that formed on the outer surface thereof as shown in Fig. 10. However, when some parts or some objects accidentally drop onto the cover in the case where the permeable film is formed on the upper surface of the cover as shown in Fig. 10, the permeable film is directly hit by the falling object and is, therefore, subject to damage. Accordingly, it is preferable to form the permeable film on the inner surface of the cover as shown in Fig. 3. In the construction shown in Fig. 3, there is still such a problem as the deformation of the permeable film or the drop thereof from the cover. Accordingly, it is further preferable to provide an additional support member 46 for supporting the lower surface of the permeable film, as shown in Fig. 11. It is also desirable to apply the bacteriaproofing and fungusproofing high in safety for fibers with respect to the base cloth and the protective fibrous layer. A quaternary ammonium salt is employed as a bacteriaproofing or fungusproofing agent and is chemically bonded on the surface of the fibers through an organic silicone as a medium. For example, a treatment called "Biosil Treatment" developed by Toyobe Co., Ltd is employed to this purpose. A further explanation will be made here with respect to the aforementioned treating agent. Although it is conventionally known that the quaternary ammonium salt restrains microbes from growing up, since it is difficult to directly chemically bond this chemical compound with the fibers, the quaternary ammonium salt and the fibers are chemically bonded with each other through the organic silicone as a crosslinker. Accordingly, the quaternary ammonium salt never dissolve in cleaning or washing, thus resulting in that a bacteriaproofing or fungusproofing effect lasts long in safety.

Claims: 1. A storage receptacle comprising: a receptacle body (2) open on its upper side; a cover member (3) for covering the opening portion of said receptacle body (2); and a permeable film member (5) having a permeability to gases and to moisture and formed at least on a portion of said receptacle body (2) and/or said cover member (3); characterized in that said permeable film member (5) covers a plurality of openings (4) formed at least in said portion of said receptacle body (2) and/or in said cover member (3) and that said permeable film member (5) is a laminated member comprising fibrous layers (5a, c) formed on opposite sides of a permeable thin resin layer (5b). 2. A storage receptacle as claimed in claim 1, wherein said permeable film member (5) is formed on said cover member (3). 3. A storage receptacle as claimed in claim 1, wherein said permeable film member (5) is formed on each of said cover member (3) and a part (7) of a side wall of said receptacle body (2). 4. A storage receptacle as claimed in claim 2, wherein said cover member (3) is of a synthetic resin formed in the shape of a plate provided with said openings (4), and said permeable film member (5) is bonded to said cover member (3) so as to cover said openings (4). 5. A storage receptacle as claimed in one of the preceding claims, wherein said moisture permeability is in the range from 1500 to 3500 g/m².24hr. 6. A storage receptacle as claimed in one of the preceding claims, wherein one of said fibrous layers is a base cloth (5a) and the other of said fibrous layers is a protective fibrous layer (5c). 7. A storage receptacle as claimed in claim 6, wherein said resinous thin film (5b) is a thin silicone resin film. 8. A storage receptacle as claimed in claim 6, wherein said resinous thin film (5b) is of polyamino acid type urethane. 9. A storage receptacle as claimed in one of claims 6 to 8, wherein said base cloth (5a) and protective fibrous layer (5c) is composed of polyester taffeta or polyester knit. 10. A storage receptacle as claimed in one of claims 6 to 9, wherein a portion of said cover (3) is thermally fusion-bonded with said base cloth (5a). 11. A storage receptacle as claimed in one of claims 6 to 10, wherein the bacteriaproofing and fungusproofing are performed with respect to said base cloth (5a) and protective fibrous layer (5c). 12. A storage receptacle as claimed in claim 11, wherein a quaternary ammonium salt is employed as a bacteriaproofing and fungusproofing agent and is chemically bonded on the surfaces of said base cloth (5a) and protective fibrous layer (5c) through an organic silicone as a medium. 13. A storage receptacle as claimed in one of claims 6 to 12, wherein said permeable resin thin layer is a silicone film (45b) formed on said base cloth (45a), an urethane thin film (45d) is formed on said silicone resin thin film (45b) and said protective fibrous layer (45c) is covered on said urethane thin film (45d) through a bond layer (45e).

Inventors: NAGATA, KOHJI
Applicants: MATSUSHITA REFRIGERATION COMPANY
Application year: 1987
Main classification: B65D65
IPC codes: B65D81, F25D17, F25D25