JPS63179731A - Moisture permeable and water impermeable laminated sheet and manufacture thereof and packaging vessel using said sheet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a moisture-permeable/water-impermeable laminated sheet suitable for packaging deliquescent dehumidifiers, a method for producing the same, and a packaging container using the same.

[Conventional technology]

When heating with a kerosene stove or the like in winter, the indoor temperature rises, causing condensation on closets, shoe cabinets, wardrobes, walls, floors, etc., and mold may grow there. Furthermore, mold also occurs during the rainy season due to condensation. Furthermore, dehumidification of futons has recently become widespread. Various types of dehumidifiers have come to be widely used in homes for this purpose.

The dehumidifier used here is mainly a desiccant such as calcium chloride or magnesium chloride that is inexpensive and has a large moisture absorption capacity. However, since these desiccants are deliquescent, they become an aqueous solution when they absorb more than a certain amount of water.

Special Publication No. 55-39363 and Special Publication No. 61-30619
No. 2, No. 1, No. 1, No. 1, No. 1, No. 1, No. 1, 2003, discloses the packaging of such deliquescent desiccant agents in microporous films. This microporous film is produced by mixing and kneading fine particles of inorganic compounds such as metal oxides, hydroxides, or salts into a thermoplastic resin such as polypropylene, forming the film into a film, and then stretching it in the axial or biaxial direction. formed by. Such microporous films are impermeable to water but have moisture permeability due to the fine particles of inorganic compounds dispersed within the film. Therefore, even if the packaged dehumidifier absorbs moisture and becomes liquefied, water leakage can be prevented.

[Problem that the invention seeks to solve]

However, it has been found that such a microporous film leaks when it comes into contact with an aqueous solution of calcium chloride or the like for a long time, or when the amount of moisture absorbed increases and the liquid pressure inside the container increases.

This problem is particularly serious when used as a packaging material for household dehumidifiers, as the leakage of deliquescent liquid contaminates furniture, walls, floors, etc. of the house.

Therefore, an object of the present invention is to provide a moisture-permeable/water-impermeable laminated sheet that has no fear of leakage of deliquescent liquid even when such a deliquescent dehumidifier is packaged.

Another object of the present invention is to provide a method for manufacturing such a moisture permeable/water impermeable laminated sheet.

Yet another object of the present invention is to provide a packaging container for a deliquescent dehumidifier using such a moisture permeable/water impermeable laminated sheet.

[Means for solving problems]

In view of the above objectives, as a result of intensive research, the present inventor discovered that a moisture-permeable and water-impermeable laminated sheet can be obtained by coating and laminating an extremely thin urethane resin film on a breathable sheet. , came up with the present invention.

That is, the moisture-permeable/water-impermeable laminated sheet of the present invention has a weight of 10 g/laminated on at least one surface of the breathable sheet.
It is characterized by having a urethane resin thin film of m2 or less.

In addition, the method for producing the moisture-permeable/water-impermeable laminated sheet of the present invention includes applying a urethane resin solution containing isocyanate groups to at least one surface of the breathable sheet in an amount of 10 glrd or less, and causing a reaction of the isocyanate groups. It is characterized by curing the urethane resin liquid.

Furthermore, the packaging container of the present invention is characterized in that the moisture-permeable/water-impermeable laminated sheet described above is used as a packaging material, and a deliquescent dehumidifier is filled and sealed therein.

Examples of the breathable sheet include a microporous resin sheet, paper, nonwoven fabric, and a plastic film perforated with needles or the like. The breathable sheet coated with urethane resin liquid weighs 10g/
It is necessary to have a sufficiently flat surface to obtain a urethane resin thin film with a thickness of rrr or less. For this purpose, microporous resin sheets, compressed nonwoven fabrics with flattened surfaces, perforated plastic films, and the like are preferred. A particularly preferred breathable sheet for applying the urethane resin liquid is a microporous resin sheet.

Microporous resin sheets can be produced by mixing plastic with soluble substances to form a sheet, then eluting the soluble substances from the sheet, sintering plastic powder,
It can be obtained by mixing plastic with an inorganic substance to form a sheet and stretching it, or by forming a crystalline plastic sheet and stretching it. Plastic materials include polyolefin resins such as polyethylene and polypropylene, fluorine resins such as polyester, nylon, and polytetrafluoroethylene, styrene resins such as polystyrene, acrylonitrile-butadiene-styrene copolymer, and polyvinyl chloride. can be used.

In particular, in the case of a microporous resin sheet obtained by stretching a plastic sheet mixed with an inorganic substance, the inorganic substance to be added has an average particle size of 0.1 to 10 μm, preferably 1 to 5 μm.
metal oxides, hydroxides, salts, etc. For example, metal oxides such as calcium oxide, alumina, and silica,
Metal hydroxides such as aluminum hydroxide and calcium hydroxide; metal salts such as calcium carbonate, magnesium chloride, magnesium carbonate, calcium sulfate, and magnesium sulfate;
Other materials that can be used include calcium silicate, cement, zeolite, and talc. A plastic sheet containing such fine particles of inorganic material can be stretched uniaxially or biaxially by about 50 to 1000%.

The microporous resin sheet thus obtained was 0.01
It has pores of ~20 μm.

The nonwoven fabric can be formed from a polyolefin such as polyethylene or polypropylene, a polyamide such as nylon, or a thermoplastic resin such as polyester or rayon. In order to apply the urethane resin liquid, the nonwoven fabric needs to have a surface as flat as possible, and for this purpose, the fibers constituting the nonwoven fabric preferably have a diameter of about 1 to 100 μm.

Further, it is preferable to heat roll or compress the nonwoven fabric to such an extent that the pores of the nonwoven fabric are not crushed. Of course, such conditions are not particularly required when the urethane resin liquid is used as a layer that is not directly applied.

Note that since the breathable sheet to which the urethane resin liquid is applied essentially acts only as a base material, it does not necessarily have to be non-water permeable as long as it has sufficient flatness and has air permeability and moisture permeability. The moisture permeability of the urethane resin thin film laminated on the breathable sheet decreases as the film thickness increases, so the film thickness needs to be 10 g/m2 or less in order to obtain sufficient moisture permeability. On the other hand, if it is too thin, it will not have enough strength to withstand the liquid pressure of the deliquescent liquid, and there is also a risk that holes will be formed in some areas, so it is preferable to have a film thickness of 0.5 g/M or more. Considering all points such as moisture permeability, water impermeability, and strength, the preferable thickness of the urethane resin thin film is 0.5 to 5 g/rd.

It is difficult to obtain such a thin urethane resin film using a normal urethane resin film forming method. For example, the thinnest ordinary thermoplastic urethane resin film has a film thickness of about 30 μm, which is too thick for the purpose of the present invention, and ordinary thermoplastic urethane resin liquid has poor adhesion to the breathable sheet. A good thin film cannot be obtained even by coating. However, it contains isocyanate groups,
It has been found that the urethane resin liquid cured by this reaction has good adhesion to the air-permeable sheet surface and can form a moisture-permeable/water-impermeable thin film.

Urethane resin liquids containing isocyanate groups and cured by this reaction include -wave type and two-part type. - Wave type is a resin liquid in which polyol and excess polyisocyanate are reacted to leave free isocyanate groups at the ends, and the isocyanate groups react with moisture and harden. The two-component type is composed of a polyol and a polyisocyanate, and when mixed, the isocyanate group and the ○H group react and are cured.

Examples of polyols include polyether polyols, polyester polyols, polyurethane polyols, acrylic polyols, and polybutadiene polyols. In addition, as a polyisocyanate, tolylene diisocyanate 1-
(TDI), 4.4'-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), metaxylylene diisocyanate (MX
DI), hexamethylene diisocyanate (1 mark ■),
Lysine diisocyanate (LDr), 4,4'-methylenebis(cyclohexyl isocyanate) ()II□M
DI), methylcyclohexane diisocyanate) (
IITDI), isocyanate methylcyclohexane (
H6χDr), l-limethylhexamethylene diisocyanate (TMDI), and the like. Note that since isocyanate monomers are toxic, they are preferably used as prepolymers. As the polyisocyanate prepolymer, for example, a polymer such as I (DI or TDI trimer),
Polyols such as trimethylolpropane and TDI,
There are adducts with polyisocyanates such as HDI, XDI, and LDI.

The above-mentioned wave-type or two-component urethane resin liquid is applied to a breathable sheet by a gravure coating method, a kiss coating method, a roll coating method, etc., and left at a temperature of room temperature to 60° C. to cause a curing reaction. Once the reaction of isocyanate groups is completed,
A thin film of cured urethane resin is obtained. In this specification, the amount of the urethane resin liquid applied is expressed based on the urethane resin content. That is, when a solvent is contained, the coating amount is expressed based on the weight of the urethane resin.

Therefore, the coating amount corresponds to the thickness of the obtained urethane resin thin film.

The thin film of urethane resin thus obtained can be made sufficiently thin to 10 g/rrr or less as described above, and therefore has extremely good moisture permeability.

The urethane resin liquid can also be made to function as an adhesive by press-bonding it to another breathable sheet immediately after application and drying. In this case, the two air-permeable sheets do not have to be the same (and the other air-permeable sheet to be crimped may be a sheet with a relatively rough surface.

In the laminated sheet of the present invention, any number of breathable sheets other than those described above may be laminated in any order as long as the surface of the breathable sheet on which the urethane resin thin film is laminated is sufficiently flat. can. In particular, in order to make a packaging container for a deliquescent dehumidifier self-supporting, that is, able to maintain a certain shape without reinforcement, it is preferable that at least one of the breathable sheets is made of paper.

When using the moisture-permeable/water-impermeable laminated sheet obtained in this way as a packaging material, it can be used for part or all of a packaging container, heat-sealed, etc. into a bag, cup, or box shape, and then used as a dehumidifier. After filling, seal it. In order to perform heat sealing, the breathable sheet on the heat sealing surface must be made of thermoplastic resin. The shape of the bag is flat bag,
There are stand pouches, gusset bags, etc. It is also possible to make a vertical container for a dehumidifier by reinforcing a blank punched from a laminated sheet with a frame made of thermoplastic resin.

Leave the necessary margin in the packaging container, taking into consideration that the dehumidifier will deliquesce and increase in volume due to moisture absorption.

[For production]

As mentioned above, the moisture-permeable/water-impermeable laminated sheet of the present invention consists of a breathable sheet and a thin film of urethane resin, and the thin film of urethane resin has high moisture permeability and has virtually no pores. Unlike porous resin sheets, it is completely impermeable to water. Therefore, even if the packaged deliquescent moisture proofing agent becomes a solution due to deliquescence, leakage is completely prevented. In addition, such a urethane resin thin film has fluidity so that it is sufficiently thin at the coating stage, and has good adhesion to the breathable sheet. It is obtained by using a liquid type urethane resin solution containing free isocyanate groups.

〔Example〕

The present invention will be explained in more detail by the following examples.
The present invention is not limited thereto.

Real W raw linear low density polyethylene (d = 0.920. Ml
= 2.0) and 50% by weight of calcium carbonate (average particle size 1.7 μm) were kneaded and granulated using a twin-screw kneader, and then a film with a thickness of 75 μm was obtained using an inflation film forming machine. - Stretched twice using an axial stretching machine to obtain a microporous film with a thickness of 50 μm. In addition, Takelac A-968 (manufactured by Narita Pharmaceutical Industries), which is a polyether polyol, and Takene 1-A-8 (manufactured by Narita Pharmaceutical Industries, Ltd.), which is a polyisocyanate,
(manufactured by Narita Pharmaceutical Industries, Ltd.) at a weight ratio of 10/8, and the resulting two-component urethane resin liquid was applied to the microporous film at a coating amount of 3 g/m2. Immediately after drying the applied urethane resin liquid, a 30 g/m polyester nonwoven fabric was pressed and adhered, and left at room temperature until the curing reaction was completed.

When the thus obtained laminated sheet was measured for air permeability, it was so large that it could not be measured.

The moisture permeability was 2000 g/rrL24hr at a temperature of 40°C and a relative humidity of 90%.

A dry laminated film of a 15 μm thick biaxially stretched nylon film and a 40 μm thick linear low-density polyethylene film was heat-sealed to the microporous sheet side of this laminated sheet to produce a pouch of 1501)XIOC1). did. This pouch was filled with 30 g of calcium chloride, and after degassing, it was sealed by heat sealing. This is 45
When stored at 95% RH for 10 days, the moisture absorption amount reached 130 g, but no leakage was observed.

On the other hand, when a similar pouch was made using only the above-mentioned microporous film, filled with the same amount of calcium chloride, sealed, and stored under the same conditions, it reached a moisture absorption of 130 g after 8 days, but calcium chloride deliquesced. Leakage of liquid was observed.

Linear low-density polyethylene film with a thickness of 60μ
A perforated film having a hole diameter of 0.2 mm and a hole number of 10/m was produced by passing the film between a rubber roll and a roll having a needle heated to 80°C.

Add 3 g of the same two-component urethane resin solution as in Example 1 to this.
After drying, a 30 g/m' polyester nonwoven fabric was immediately bonded. The moisture permeability of the obtained laminated sheet was 1900g/bar, 24hr (40°C, 90%RH)
Met. A calcium chloride-filled pouch was prepared from this laminated sheet in the same manner as in Example 1, and the temperature was 45°C x 95%RH.
It was stored under the following conditions. 1) Although the amount of moisture absorption reached 130g after 1 day, there was no leakage.

After kneading 30% by weight of Daiarashi base polypropylene and 70% by weight of calcium carbonate (average particle size 1.7 μm), the mixture was granulated, and a sheet with a thickness of 150 μm was obtained using a T-die film forming machine.
A microporous sheet of 90 μm was obtained by two-wheel stretching 5×2.5 times. In addition, Takene Rank 712B (manufactured by Narita Pharmaceutical Co., Ltd.) as a polyether polyol and Takene 1-72B (manufactured by Narita Pharmaceutical Co., Ltd.) as a polyisocyanate are mixed at a weight ratio of 10Z8, and the resulting two-component urethane resin liquid is mixed with the above-mentioned microorganism. It was applied to a porous sheet at a coating weight of 4 g/m, and a 40 g/nr polyethylene nonwoven fabric was adhered thereon. The moisture permeability of the laminated sheet thus obtained is 1500 g/rd・under conditions of 40°C and 90% RH.
It was 24 hours. A pouch was made by heat sealing with the nonwoven fabric side facing inside, and the same test as in Example I was conducted. After 15 days, the pouch was 130. Although the moisture absorption reached 1.5 g, there was no leakage. On the other hand, a pouch formed by thermally laminating a microporous film and a nonwoven fabric reached a moisture absorption ff of 180 g after 9 days, but leakage occurred.

1) A urethane resin solution was applied in the same manner as in Example 1 to a compressed non-woven fabric sheet ("Tai Rin Tsuku", manufactured by DuPont) with a flat surface of 0 g/rrr, and then g/m
2 polyester nonwoven fabrics were laminated. The resulting laminated sheet has a moisture permeability of 2000 at 40°C and 90% RH.
g/rd・24hr. Furthermore, using this laminated sheet, a 30 g calcium chloride-filled pouch was prepared in the same manner as in Example 1, and a leakage test was performed.The pouch reached a moisture absorption of 130 g after 10 days, but no leakage was observed. This shows that nonwoven fabrics with flat surfaces are also effective as substrates for coating urethane resin liquids.

Example 1 except that instead of the two-component urethane resin solution, a one-wave type urethane resin solution (Dismodur@1240, manufactured by Sumitomo Bayer) containing 3.3% of free isocyanate groups was used. A laminated sheet was produced by a similar method.

The moisture permeability of this laminated sheet was 1900 g/n (・24 hr) under the conditions of 40°C and 90% RH.
When a leakage test was conducted as a calcium chloride-filled pouch in the same manner as above, the moisture absorption amount reached 130 g after 1) day, but no leakage was observed.

A laminated sheet was prepared in the same manner as in Example 1, except that 70 g/td paper was used instead of the polyester nonwoven fabric, but its moisture permeability was 2000 g under the conditions of 40°C and 90% RH. /rd・24hr. Further, when a leakage test was conducted under the same conditions as in Example 1, no leakage was observed.

Punch out the laminated sheet produced in Example 1 of the tip construction,
A blank 1 having the shape shown in FIG. 1 was produced. This blank 1 is held in a mold and plastic is injected to form a frame 2.
A packaging container having the shape shown in FIG. 2 was produced by integrally molding. This packaging container (capacity: 200 ml) was filled with 50 g of calcium chloride, and the lid 3 was heat-sealed. When this was stored under the same conditions as in Example 1, no leakage was observed even after the calcium chloride inside was completely deliquesced.

〔Effect of the invention〕

As explained above, the laminated sheet of the present invention formed by applying a thin film of urethane resin has sufficient moisture permeability and is impermeable to water, and in particular, does not leak at all even against deliquescent liquid of a deliquescent dehumidifier. No worries.

Therefore, this laminated sheet is extremely effective as a packaging material for deliquescent dehumidifiers. In addition, such laminated sheets can be easily processed into bags or containers of any shape, so
It can be used in various dehumidifier applications.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a packaging container blank formed from the laminated sheet of the present invention, and FIG. 2 is a perspective view showing a dehumidifier container formed using the blank of FIG. 1. 1... Blank, 2... Framework, 3... Lid. Applicant: Dai Nippon Printing Co., Ltd.

Claims (10)

[Claims] (1) A moisture-permeable/water-impermeable laminated sheet characterized by having a urethane resin thin film of 10 g/m^2 or less laminated on at least one surface of the breathable sheet. (2) The moisture-permeable/water-impermeable laminated sheet according to claim 1, wherein the breathable sheet on which the urethane resin thin film is laminated is a microporous resin sheet. Non-water permeable laminated sheet. (3) Moisture permeability according to claim 1 or 2.
In the non-water permeable laminated sheet, the urethane resin thin film is sandwiched between the two breathable sheets, and at least one of the breathable sheets is a microporous resin sheet. laminated sheet. (4) Moisture permeability according to claim 2 or 3.
A moisture-permeable/water-impermeable laminated sheet, wherein the breathable sheet other than the microporous resin sheet is any one of paper, nonwoven fabric, and perforated film. (5) In the moisture permeable/water impermeable laminate sheet according to any one of claims 1 to 4, the thickness of the urethane resin thin film is 0.5 to 5 g/m^2. A moisture permeable/impermeable laminated sheet featuring: (6) Moisture-permeable sheet with a urethane resin thin film of 10 g/m^2 or less laminated on at least one surface of the breathable sheet.
In the method for producing a water-impermeable laminated sheet, a urethane resin solution containing isocyanate groups is applied to at least one surface of the breathable sheet at a coating amount of 10 g/m^2 or less, and the reaction of the isocyanate groups causes A method characterized by curing a urethane resin liquid. (7) The method for producing a moisture permeable/water impermeable laminate sheet according to claim 6, characterized in that the content of isocyanate groups in the urethane resin liquid is 0.1 to 30%. how to. (8) Moisture permeability according to claim 6 or 7.
A method for producing a water-impermeable laminated sheet, characterized in that the breathable sheet to which the urethane resin liquid is applied is a microporous resin sheet. (9) 1 laminated on at least one side of the breathable sheet
A packaging container for a deliquescent dehumidifier, characterized in that the packaging material is a moisture permeable/water impermeable laminated sheet having a urethane resin thin film of 0 g/m^2 or less. (10) A packaging container for a deliquescent dehumidifier according to claim 9, comprising a blank obtained by punching out the moisture-permeable/water-impermeable laminated sheet and a framework of thermoplastic resin; A packaging container characterized by filling and sealing a deliquescent dehumidifier.