JPH0280236A - Freshness maintaining sheet - Google Patents

Abstract

PURPOSE:To maintain proper humidity by integrating an outer layer constituted of micro-porous non-woven cloths formed by heat fusion of heat fusion fibers, an intermediate layer including high water absorption fibers and an inner layer constituted of water permeating non-woven cloth consisting of heat fusion bonding fibers connecting the spaces among the fibers. CONSTITUTION:As a microporous non-woven cloth as an outer layer 12 is constituted of heat fusion fibers, mixture permeability and water permeating properties of the outer layer 12 can be set selectively by changing properly the content, melting temperature and the like of the heat fusion fibers included therein. An intermediate layer 13 is a fiber layer which is turned into a sheet by the conventional process in the state that high water absorption fibers absorbing surplus water from vegetables, fruits and the like only by themselves or in the state that hydrophilic fibers are added therein and manufactured in the given volume. An inner layer 14 is a water permeating fiber layer covering the intermediate layer 13 together with the outer layer 12, and turned into a sheet by the conventional process in the state of including heat fusion bonding fibers and manufactured into the given volume. Respective fiber layers are integrated by overlapping the intermediate layers 13, the outer layer 12 and the inner layer 14 and, for instance, needling the same.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a freshness-keeping sheet, and more particularly to a freshness-keeping sheet that can adjust moisture content by itself.

(Prior Art) Various freshness-keeping sheets have been proposed for wrapping vegetables, fruits, etc. to maintain their freshness during transportation.

For example, as shown in Figure 4, between two sheets of paper (2), a water absorbing agent (3) made of powdery water-absorbing molecules and a gas adsorbent (4) also in powder form are placed between two sheets of paper (2). and also this paper (
A sheet (1) made by covering 2) with a bag body (5) made of non-woven fabric is commercially available. Since this sheet (1) has the above-mentioned structure, it prevents stuffiness caused by excessive humidity and so-called water staining caused by condensed water, and also prevents moisture from forming in the sheet (1).
1) Vegetables, fruits, etc. are prevented from drying out because they are held inside. However, when using this sheet (1) as a freshness preservation sheet,
In order to prevent moisture evaporated from vegetables, fruits, etc. from leaching out from the sheet (1) when vegetables, fruits, etc. are wrapped,
It was necessary to cover the exterior with a water-impermeable film. As a result, the air permeability of the sheet (1) is impaired, and vegetables, fruits, etc., rot due to retention of ethylene gas, etc. or,
When this sheet (1) is cut, the powdered moisture absorbing agent (3) and gas adsorbing agent (4) inside the sheet (1) spill out, so it was not possible to cut it into any size and use it. .

In addition, as another freshness preservation sheet, JP-A-55-132
There is one described in Publication No. 754.

As shown in FIG. 5, this sheet (10) is made of super absorbent fibers mixed with synthetic fibers such as polyvinyl alcohol #l fibers, and contains The super absorbent fiber absorbs moisture generated from vegetables, fruits, etc., and prevents stuffiness and water-staining of vegetables, fruits, etc. due to excessive humidity. Also, this sheet (10)
Since it is composed of highly absorbent fibers and synthetic fibers, it can be cut into any size for wrapping vegetables, fruits, etc. when used.

(Problem to be Solved by the Invention) However, since this sheet is composed of highly water-absorbent fibers and synthetic fibers, the water generated from vegetables, fruits, etc. Although water is once absorbed by the fibers, it is not retained in the sort and immediately evaporates through the sheet, making it impossible to maintain the appropriate humidity of vegetables, fruits, etc. within the sheet.

Furthermore, when moisture generated from vegetables, fruits, etc. is absorbed by the highly absorbent fibers contained in the sheet, when pressure is applied to the sheet, the absorbed moisture sometimes leaches out of the sheet. For this reason, even with this sheet, it was necessary to cover vegetables, fruits, etc. with a non-water-permeable film in order to maintain appropriate humidity and prevent moisture from seeping out when water is absorbed. As a result, the film impairs the air permeability of the sheet, causing ethylene gas and the like to remain, leading to rotting of vegetables, fruits, and the like.

The present invention has been made in view of these problems, and it is an object of the present invention to provide a freshness-keeping sheet that can adjust the moisture content of the sheet alone.

(Means for Solving the Problems) That is, the invention according to claim 1 has an outer layer made of a microporous nonwoven fabric formed by heat fusion of heat-fusible fibers, and an intermediate layer containing highly water-absorbent arts. and.

This is a freshness-preserving sheet that is integrated with an inner layer made of a water-permeable nonwoven fabric bonded by heat-fusible fibers at m intervals.

Moreover, the invention according to claim 2 is a freshness-keeping sheet characterized in that the intermediate layer contains hydrophilic fibers.

Further, the invention according to claim 3 is a freshness-keeping sheet characterized in that the intermediate layer contains highly crimped fibers.

Moreover, the invention according to claim 4 is a freshness-keeping sheet characterized in that an outer layer, an inner layer, and an intermediate layer are integrated by needling.

(Action of the invention) Therefore, in the freshness-keeping sheet according to claim 1, when vegetables, fruits, etc. are wrapped with the freshness-keeping sheet, the inner layer is bonded between the fibers by the heat-melted heat-fusible fibers. Excess water evaporated from vegetables, fruits, etc., passes through and is absorbed by the super absorbent fibers in the middle layer. At this time, the outer layer is a microporous nonwoven fabric made of heat-fusible fibers and has a large number of pores that allow only gas to pass through, which prevents water from permeating through it. Excess moisture that has evaporated is retained within the freshness preservation sheet. On the other hand, as the vegetables, fruits, etc. wrapped in the freshness preservation sheet continue to dry, the moisture absorbed in the middle layer returns through the inner layer, and moisture is supplied to the vegetables, fruits, etc. There is. In addition, gases such as ethylene gas generated from vegetables, fruits, etc. inside the freshness-keeping sheet are released outside the freshness-keeping sheet through the pores of the microporous nonwoven fabric made of molten heat-fusible fibers formed in the outer layer. It is now possible to do so.

Further, in the freshness-keeping sheet according to the second aspect, water absorbed along the hydrophilic fibers included in the intermediate layer is diffused throughout the intermediate layer.

Furthermore, in the freshness-keeping sheet according to claim 3, the highly crimped fibers contained in the intermediate layer further enhance the tightness of the intermediate layer.

(Example) Hereinafter, the freshness retaining sheet of the present invention will be described in detail according to an example shown in the drawings.

FIG. 1 is a perspective view showing one embodiment of the freshness-keeping sheet of the present invention, FIG. 2 is an enlarged sectional view schematically showing the freshness-keeping sheet of the present invention, and FIG. 3 is another example of the present invention. FIG. 2 is an enlarged cross-sectional view schematically showing.

As shown in FIGS. 1 and 2, the freshness-keeping sheet (11) of the present invention consists of an outer layer (12), an intermediate layer (13), and an inner layer (
14).

The outer layer (12) is made of heat-fusible fibers alone or with hydrophobic fibers added to a sheet by a conventional method to have a predetermined volume. It is a microporous nonwoven fabric made of heat-fusible fibers or heat-fused. The content of heat-fusible fibers in the outer layer (12) is 50% to 100%, preferably 80% to 100%, and the remainder other than 100% contains hydrophobic fibers for the purpose of suppressing water permeation. Contains Outer layer (12)
In this method, a web is formed from heat-fusible fibers such as polyethylene component fibers, low-melting point polyester fibers, or composite fibers made of polyethylene components and polypropylene components, and each fiber is bonded with a binder such as an acrylic binder. Then, heat-press it to form a sheet, or mix heat-fusible fibers with hydrophobic fibers such as polyester M fibers to form a web, adhere each FA fiber using a binder, and heat-press this to form a sheet. I can list things that have been changed. Note that the web may be bonded using heat-fusible fibers forming the microporous nonwoven fabric as a binder.

The microporous nonwoven fabric formed when hot-pressed into a sheet is a dense and thin nonwoven fabric formed by heat-sealing heat-fusible fibers.

A large number of holes are formed that are sized to allow substantially only gas to pass through. For this reason, the outer layer (12) allows gases such as ethylene gas to freely pass through it, but makes it difficult for moisture to pass through it. In addition, since the microporous nonwoven fabric is made of molten heat-fusible fibers, the size and area of the pores can be freely set by appropriately changing the content of the heat-fusible fibers contained, the melting temperature, etc. This allows the outer layer (12)
It is now possible to selectively set the moisture permeability and water permeability of the material. In addition, the content of heat-fusible fibers and heating temperature in the outer layer (12) are determined according to the freshness-keeping sheet (It
) should be determined appropriately, taking into consideration the usage conditions and shape of the device. This is because if the content of heat-fusible fiber is 100%, if heated at too high a temperature, the amount of heat-fusible fiber that will be melted by heating will increase, making the outer layer (12) too stiff. This is because if the content is less than 50%, the amount of heat-fusible fibers that melt when heated will be small and water will easily permeate. This is because it causes the disadvantage of In addition, in order to further suppress the permeation of moisture, the outer layer (1
For 2), it is preferable to use fibers that have been subjected to hydrophobic treatment with a hydrophobic oil agent, and may also be treated with water repellent agents such as silicone-based or fluorine-based water repellents. This outer layer (
An intermediate layer (13) is laminated inside the layer (12).

The middle layer (13) is made of highly absorbent fibers that absorb excess water from vegetables, fruits, etc., either alone or with the addition of hydrophilic laminated fibers, which are made into a sheet by a conventional method to have a predetermined volume. It is a layer. The content of superabsorbent #a fibers in the intermediate layer (13) is between 10% and 100%, preferably 50%
~100%, and the remainder other than 100% contains hydrophilic m*. For the middle 1) +' layer (+3), acrylic #1, fiber made by crosslinking acrylate/acrylamide copolymer, or rayon fiber made of CMC
A web is formed using highly water-absorbent fibers that have been modified to have high water-absorbency and have a water absorption capacity of 25 times or more relative to pure water. A preferred example is one in which fibers are bonded and heated to form a sheet. In addition, as described in claim 2, if hydrophilic M& fibers such as rayon and cotton are mixed with super absorbent fibers, the absorbed water will flow along the hydrophilic fibers included in the intermediate layer (13). Since it becomes diffused throughout the intermediate layer (13),
It is possible to avoid spot absorption of water as in the case of only super absorbent tR fibers. In addition, by adding hydrophilic M fibers to super absorbent fibers and further adding bulbs or hydrophobic A fibers, or as in claim 3, highly crimped fibers such as highly crimped polyester fibers can be added to super absorbent fibers. By mixing the fibers, water is more efficiently diffused throughout the intermediate layer (13). An inner layer (14) is laminated on the inside of this intermediate layer (13), that is, on the side of vegetables, fruits, etc.

The inner layer (14), together with the outer layer (12), is an intermediate layer (1).
3) is a water-permeable fiber layer that covers 3), and is formed into a sheet by a conventional method in a state containing heat-fusible fibers to have a predetermined volume. In this inner layer (14), the 1 m fibers constituting the inner layer (14) are bonded by melted heat-fusible fibers to improve the strength of the inner layer (14) and prevent fibers from coming out. Moreover, this inner layer (14) prevents a highly water-absorbent material from contacting a gel-like substance generated by water absorption, vegetables and fruits, and reducing its commercial value. Heat fusion properties in the inner layer (14)! @Miscellaneous content is 1
The content is 0% to 50%, preferably 20% to 50%, and the remaining fibers are preferably hydrophilic fibers because they are compatible with excess water evaporated from vegetables, fruits, etc. However, even if the fiber is hydrophobic, it can be suitably used as long as it has been treated with a hydrophilic oil to make it lignophilic.

In addition, an inner layer (14) with high bulkiness can be obtained by mixing highly crimped fibers such as highly crimped polyester fibers with the fibers constituting the inner layer (14).
The freshness retaining sheet (11) obtained by using the above method is rich in cushioning properties, and when used to wrap vegetables, fruits, etc., it can eliminate damage to the vegetables, fruits, etc. that occurs during transportation.

The outer layer (I2), the middle layer (13), and the inner layer (14) mentioned above
), any conventionally known method may be used to integrate the fiber layers of the intermediate layer (13
), the outer layer (12), and the inner layer (14) were overlapped and needled to integrate each fiber layer. Note that the present invention is not limited to this, and an adhesive may be interposed between each fiber layer, and each fiber layer may be bonded and integrated with this adhesive.

Alternatively, a web or web-shaped sheet made of heat-fusible fibers may be laminated on the overlapping surface of each fiber layer, and each fiber layer may be heat-fused by the sheet.

As shown in FIG. 3, a perforated film (11) made of a synthetic resin such as low density polyethylene, high density polyethylene, polypropylene, or soft vinyl chloride resin is placed inside the freshness preserving sheet (11) of the present invention described above. 15), the inner surface of the freshness preservation sheet (11) will be smooth, and when vegetables, fruits, etc. are wrapped, fibers and gel-like substances will adhere to the vegetables, fruits, etc. and reduce the commercial value. It is possible to more completely prevent the decline.

Next, a method of using the freshness preservation sheet of the present invention described above will be explained.

As shown in FIGS. 1 and 2, when vegetables, fruits, etc. are wrapped with the freshness-preserving sheet (11) of the present invention, when the humidity within the freshness-preserving sheet (11) reaches about 85% or more,
Excess moisture evaporated from vegetables, fruits, etc., passes through the inner layer (14) where the fibers are bonded by heat-fused heat-fusible fibers and is absorbed by the super absorbent fibers of the middle layer (13). It has become. At this time, the outer layer (12), which is a microporous nonwoven fabric made of heat-welded heat-fusible fibers and has many pores sized to allow only gas to pass through, blocks moisture from permeating! ? Excess moisture evaporated from vegetables, fruits, etc. is retained within the freshness-preserving sheet.

On the other hand, if the vegetables, fruits, etc. wrapped in the freshness-preserving sheet (11) continue to dry and the humidity inside the freshness-preserving sheet (11) becomes about 85% or less, the intermediate level is reached! The moisture absorbed by (13) permeates through the inner layer (14) and returns, supplying moisture to vegetables, fruits, etc. Therefore, the freshness-keeping sheet (11) is suitable as an inner packaging material for containers for transporting perishable fruits such as melons, watermelons, and grapes, or as storage bags for storing vegetables in refrigerators.

(Effects of the Invention) As described in detail above, in the freshness-keeping sheet according to claim 1, when vegetables, fruits, etc. are wrapped with the freshness-keeping sheet, the heat-melted heat-fusible fibers create a bond between the fibers. Excess moisture evaporated from vegetables, fruits, etc., passes through the bonded inner layer and is absorbed by the superabsorbent fibers in the middle layer. At this time, the outer layer is a microporous nonwoven fabric made of heat-fusible fibers and has many pores that are large enough to allow only gas to pass through, which prevents moisture from permeating through the skin. Excess moisture that has evaporated is retained within the freshness preservation sheet.

On the other hand, as the vegetables, fruits, etc. wrapped in the freshness preservation sheet continue to dry, the moisture absorbed in the middle layer returns through the inner layer, and moisture is supplied to the vegetables, fruits, etc. There is. Therefore, water can be adjusted using the freshness-keeping sheet alone, and there is no need to cover it with a water-impermeable film as shown in the conventional example, resulting in a simpler structure. In addition, gases such as ethylene gas generated from vegetables, fruits, etc. wrapped in the freshness-preserving sheet pass through the pores of the microporous nonwoven fabric made of molten heat-fusible fibers formed on the outer layer to the outside of the freshness-preserving sheet. It is designed to be released in Therefore, vegetables, fruits, etc. do not rot due to the retention of gases such as ethylene gas, and claim 1
The freshness-preserving sheet described above has cushioning properties even if wrapped vegetables, fruits, etc. collide or rub against each other due to shakes and vibrations during transportation, since the freshness-preserving sheet is composed of fibers. This softens the impact and makes vegetables, fruits, etc. less susceptible to damage.

In addition, in the freshness-keeping sheet according to claim 1, since water is absorbed by the superabsorbent fibers contained in the intermediate layer, the sheet can be freely cut into desired sizes and shapes. can be used.

Further, according to the freshness-keeping sheet according to claim 2, the absorbed water is diffused throughout the middle layer along the hydrophilic fibers included in the middle layer, so that the freshness-keeping sheet absorbs water spot-wise. It is possible to avoid partial expansion of

Furthermore, if the intermediate layer contains highly crimped fibers as in the freshness-keeping sheet of claim 3, the cushioning properties of the highly crimped fibers are added to the intermediate layer, and the cushioning properties of the freshness-keeping sheet are improved. It increases even more.

Moreover, in the freshness-keeping sheet according to claim 4, since the outer layer, the middle layer, and the inner layer are integrated by needling, it becomes more difficult for the layers to separate.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of the freshness-keeping sheet of the present invention, FIG. 2 is an enlarged sectional view schematically showing the freshness-keeping sheet of the present invention, and FIG. 3 is another example of the present invention. FIG. 4 is a partially cutaway perspective view showing a conventional freshness-keeping sheet, and FIG. 5 is another conventional freshness-keeping sheet 1 to 1.
FIG. Explanation of symbols 12...outer layer, 13...middle layer, 14...inner layer.

Claims (2)

[Claims] (1) An outer layer made of a microporous nonwoven fabric formed by thermally fusing heat-fusible fibers, an intermediate layer containing highly water-absorbent fibers, and a water-permeable structure in which the fibers are bonded by the heat-fusible fibers. A freshness preservation sheet that is integrated with an inner layer made of nonwoven fabric. (2) The freshness-keeping sheet according to claim 1, wherein the intermediate layer contains hydrophilic fibers. (3) The freshness-keeping sheet according to claim 1, wherein the intermediate layer contains highly crimped fibers. (4) The freshness-keeping sheet according to claim 1, 2 or 3, wherein the outer layer, the inner layer and the intermediate layer are integrated by needling.