JPH0481945B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a composite sheet having air permeability, and more particularly to a composite sheet having at least one thermoplastic material having a plurality of slits on a base sheet having air permeability. The present invention relates to a breathable composite sheet in which polymer films are laminated. Furthermore, the present invention relates to a method of manufacturing the above-mentioned breathable composite sheet by using a method of forming the above-mentioned slits using a large number of filaments.

[Conventional technology]

Packaging containing disposable body warmers, desiccants, insecticides, dehumidifiers, bath salts, fragrances, deodorizers, oxygen absorbers, etc., does not allow oxygen or other gases to be taken in from the outside or to remove certain gases from the contents. It is required to have controlled air permeability in order to allow it to be exposed to the outside.

Conventionally, various methods have been employed to impart air permeability to a composite film in which a plurality of films are laminated. For example, perforations can be made by scratching the film surface, passing the composite film over a roll with a large number of needles, or passing it between two gripping rolls with fine irregularities. There is. However, these methods themselves and the resulting breathable composite sheets were by no means satisfactory. In other words, (a) the air permeability imparted by these methods varies greatly and is not constant; (b) the manufacturing cost of the perforation process for composite films cannot be ignored; and (c) the method of scratching the film surface does not damage the film surface. There were problems such as the generation of unnecessary scratches on the packaging material, which impairs the strength and appearance of the packaging material.

[Problem that the invention seeks to solve]

An object of the present invention is to solve the problems of the above-mentioned conventional techniques, to provide a composite film having arbitrary and small variation in air permeability, and to provide a method for manufacturing such a composite film with industrial advantage. There is something to do.

[Means for solving problems]

The above purpose is to provide a base sheet having air permeability;
and at least one thermoplastic polymer film laminated thereon, the film including a broken portion having a desired width and a plurality of parallel tear edges on the base sheet. This is achieved by the breathable composite sheet of the present invention.

The breathable composite sheet of the present invention comprises a breathable base sheet and a thermoplastic polymer film A that has just been melt-extruded from a T-die, with a large number of mutually parallel filaments arranged between them. The molten film A is held and pressed between a cooling roll and a press roll in a sandwiched state, and the molten film A is cooled and solidified on the surface of the cooling roll to form a composite film, and then the solidified film A and the above film sandwiched between the base sheet are By peeling the filament from the base material into the film formed by cooling, a fracture portion (hereinafter referred to as slit) having a large number of mutually parallel tear edges penetrating the layer of the solidified film A in the thickness direction is formed. The first type is characterized by the formation of
Manufactured by the method of

The above-mentioned breathable composite sheet also includes a breathable base sheet, a large number of mutually parallel filament bodies, a thermoplastic polymer film A immediately after being melt-extruded from a T-die, and other preformed thermoplastic films. Plastic polymer film B is gripped and pressed between a cooling roll and a press roll so as to be laminated in this order, and molten film A is cooled and solidified on the surface of the cooling roll to form a composite film, and then, The solidified film A layer and the film B layer are penetrated in the thickness direction by peeling the filament sandwiched between the solidified film A and the base material sheet from the base material toward the solidified film side. The second method is characterized in that a large number of mutually parallel slits are formed.

The above-mentioned breathable composite sheet further includes a composite film formed by cooling and solidifying the molten film A in the above-mentioned first method, and another thermoplastic polymer film C immediately after being melt-extruded from a T-die. is gripped and pressed between a cooling roll and a press roll so that the solidified film A side of the composite film is in contact with the molten film C, and the molten film C is cooled and solidified on the surface of the cooling roll. By peeling the embedded filament from the base sheet toward the composite film, a large number of mutually parallel strips penetrating the layer of solidified film A and the layer of solidified film B in the thickness direction are formed. It is manufactured by a third method characterized by forming a slit.

The above-mentioned breathable composite sheet further includes a breathable base sheet, a large number of mutually parallel filaments,
The thermoplastic polymer film A immediately after being melt-extruded from the T-die and the other preformed thermoplastic polymer film or metal foil B' are laminated in this order using a cooling roll and a press roll. The molten film A is gripped and pressure-bonded to form a composite film by cooling and solidifying it on the surface of a cooling roll, and then the composite film and another thermoplastic polymer film C' immediately after being melt-extruded from a T-die. are gripped and pressed by a cooling roll and a press roll so that the film or metal foil B' of the composite film is in contact with the molten film C', and the molten film C' is cooled and solidified on the surface of the cooling roll, and then , by peeling off the filament embedded in the composite film from the base sheet toward the composite film side, a layer of solidified film A, a layer of film or metal foil B', and a solidified film C are formed. It is manufactured by a fourth method characterized by forming a large number of mutually parallel slits penetrating the layer ' in the thickness direction.

EMBODIMENT OF THE INVENTION Hereinafter, the breathable composite sheet of the present invention and its manufacturing method will be specifically described with reference to the accompanying drawings.

FIG. 1 is an enlarged sectional view schematically showing an example of the laminated structure of the breathable composite sheet of the present invention.
The figure is a perspective view of this breathable composite sheet.

As shown in FIGS. 1 and 2, the simplest and typical breathable composite sheet of the present invention is a breathable composite sheet in which a breathable base sheet 1 and a large number of parallel slits 3 are provided. Thermoplastic polymer film 2
It has a laminated structure consisting of. The material and thickness of the base sheet are not particularly limited as long as the base sheet has appropriate air permeability. Base sheets include cellulose pulp paper, synthetic fiber paper, woven fabric,
Non-woven fabrics, films with fine ventilation holes, etc. can be mentioned. Examples of the thermoplastic polymer constituting the film 2 include film-forming thermoplastic polymers suitable for extrusion lamination, such as polyethylene, ethylene, vinyl acetate copolymer, polypropylene, and polyethylene ionomer.

The thermoplastic polymer film layer 2 of the breathable composite sheet has a large number of mutually parallel slits 3, and these slits 3 penetrate the film 2 in the thickness direction. The width of the slits 3 and the number of slits per unit area are appropriately selected depending on the desired air permeability of the composite sheet.

FIG. 9 is an enlarged sectional view showing the principle of the method of the present invention. As will be described in detail below, the base sheet 1 and the film 2 are bonded together with the filament 8 interposed therebetween to form a composite film (FIG. 9A). Next, after the film 2 is cooled and solidified, the linear body 8 is peeled off from the base sheet 1 toward the film side. This forms a break 17 having a tear edge 16 .

The breathable composite sheet shown in FIGS. 1 and 2 is manufactured by the first method. This method can be carried out either batchwise or continuously, with continuous being preferred. A preferred apparatus used to carry out this first method is shown in FIG.

In FIG. 5, a base sheet 1 pulled out from a roll, a large number of endless mutually parallel filament bodies 8, and a thermoplastic polymer film 2 melt-extruded from a T-die are combined with the base sheet 1. The film 2 is held and pressed between a cooling roll 11 and a press roll 12 with the filament 8 sandwiched therebetween. By laminating in this manner, a composite film is formed.
While the composite film revolves around the cooling roll 11, the molten film 2 is cooled and completely solidified. When the composite film reaches the peeling position 10, the endless filament 8 sandwiched between the film 2 and the base sheet 1 is peeled off from the base 1 toward the film 2 side.
By this peeling, a large number of slits are formed that penetrate the layers of the film 2 in the thickness direction. The breathable composite sheet thus formed has a laminated structure as shown in FIG.

As the striatal body 8, piano wire, polyester,
Synthetic fiber yarn such as polyamide, monofilament, cotton yarn, etc. are used. The thickness and wiring density of the filament 8 are appropriately selected depending on the desired air permeability of the composite film.

The breathable composite sheet shown in FIG. 3 has a three-layer structure consisting of a base sheet 1, a thermoplastic polymer film 2, and another thermoplastic polymer film 4.
A large number of parallel slits 3 are formed in the films 2 and 4, passing through them in the thickness direction. The film 2 and the base sheet 1 are the same as those shown in FIG. 1, but the thermoplastic polymer constituting the film 4 is the same as in the case of the film 2, such as polyethylene, ethylene/vinyl acetate copolymer, etc. You can choose from thermoplastic polymers.

The breathable composite sheet shown in FIG. 3 is manufactured by the second method. A preferred apparatus used to carry out this second method is shown in FIG. The apparatus shown in FIG. 6 is similar to that of FIG. 5, but with a base sheet 1, a filament 8, a melt-extruded thermoplastic polymer film 2, and a preformed thermoplastic polymer film. 4 are combined by the cooling roll 11 and the press roll 12, and when the filament 8 is peeled off from the base sheet 1 toward the film side at the peeling position 10, both the film 2 and the film 4 are separated from each other. A slit passing through the thickness is formed.

The breathable composite sheet shown in FIG. 4 has a four-layer structure consisting of a base sheet 1, a thermoplastic polymer film 2, another thermoplastic polymer film or metal foil 5, and another thermoplastic polymer film 6. have
The base sheet 1 and film 2 may be the same as those shown in FIG. The film or metal foil 5 can be selected from thermoplastic polymer films similar to the film 2, aluminum foils, and other metal foils. Further, the film 6 can also be selected from thermoplastic polymer films similar to the film 2.

The breathable composite sheet shown in FIG. 4 is manufactured by the fourth method. A preferred apparatus used to carry out the fourth method is shown in FIG. In the apparatus shown in FIG. 7, a base sheet 1, a filament 8, a melt-extruded thermoplastic polymer film 2, and another preformed thermoplastic polymer film or metal foil 5 are integrated in this order. After the laminated molten film 2 is cooled on the circumferential surface of the cooling roll 11, the melt-extruded thermoplastic polymer film 6 is further placed on top of this laminate by a second cooling roll and a second press roll. It is pasted at. When the laminated film reaches the peeling position 10, the endless filament 8 is peeled off from the base sheet 1 toward the laminated film, and the film 2, the film or metal foil 5, and the film 6 are separated in their thickness direction. A penetrating slit is formed.

Note that the breathable composite sheet having the three-layer structure shown in FIG. 3 can be obtained by the third method instead of the second method.
It can also be manufactured by the following method. Said third
The method can be carried out using an apparatus similar to that shown in FIG. 7 (however, the film or metal foil 5 is not supplied). It goes without saying that various composite sheets can be made by using a laminate previously formed as a film or metal foil 4 or 5 in these methods.

The thermoplastic polymer film on the side opposite to the base sheet of the breathable composite film of the present invention preferably comprises a heat-sealable polymer, such as polyethylene and ethylene-vinyl acetate copolymer.

In addition, in order to impart morphological stability and strength to the breathable composite film of the present invention (in particular, an expanding force acts in a direction perpendicular to a large number of parallel slits and the slit width expands, resulting in ventilation In order to avoid an increase in the temperature, it is recommended to use a hot press or a hot roll to form a number of seams 15 extending parallel to each other in a direction perpendicular to the slit 3, as shown in FIG. desirable.

〔Effect of the invention〕

The composite sheet of the present invention is a heat-sealable sheet having arbitrary air permeability with small variations. Therefore, the composite sheet of the present invention is useful as a packaging bag for storing disposable body warmers, desiccants, insecticides, dehumidifiers, bath additives, perfumes, deodorizers, oxygen absorbers, and the like.

When manufacturing the composite sheet of the present invention, forming a laminated sheet and imparting air permeability can be performed in the same process by combining a thermoplastic polymer melt extrusion lamination method and a technique using a filament. This is extremely advantageous industrially.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view schematically showing an example of the laminated structure of the breathable composite sheet of the present invention, and FIG. 2 is a perspective view of this breathable composite sheet. FIG. 3 is an enlarged sectional view schematically showing another example of the laminated structure of the breathable composite sheet of the present invention, and FIG. 4 is a schematic diagram of still another example of the laminated structure of the breathable composite sheet of the present invention. FIG. FIG. 5 shows an example of an apparatus for producing the breathable composite sheet of the present invention, and FIG. 6 shows another example of a similar apparatus,
FIG. 7 is a diagram showing a similar device and yet another example. FIG. 8 is a perspective view showing another example of the breathable composite sheet of the present invention. FIG. 9 is an enlarged sectional view showing the principle of the method of the present invention. DESCRIPTION OF SYMBOLS 1... Base sheet, 2... Film, 8... Linear body, 16... Tear edge, 17... Broken part.

Claims (1)

[Claims] 1. Consisting of a breathable base sheet and at least one thermoplastic polymer film laminated thereon, the film has a desired width on the base sheet. A breathable composite sheet comprising a broken portion having a plurality of tear edges parallel to each other. 2. The air-permeable base sheet and the thermoplastic polymer film A that has just been melt-extruded from the T-die are rolled with a cooling roll with a large number of parallel filaments sandwiched between them. The molten film A is gripped and pressed with a press roll, and the molten film A is cooled and solidified on the surface of the cooling roll to form a composite film.Then, the filamentous body sandwiched between the solidified film and the base sheet is placed on the side of the solidified film. A breathable composite characterized in that, by peeling it off from the base sheet, a broken part having a large number of mutually parallel tear edges penetrating in the thickness direction is formed in the solidified layer of film A. Method of manufacturing sheets. 3. A base sheet having air permeability, a large number of mutually parallel filament bodies, a thermoplastic polymer film A immediately after being melt-extruded from a T-die, and another pre-formed thermoplastic polymer film B, The molten film A is gripped and pressed by a cooling roll and a press roll so as to be laminated in this order, and the molten film A is cooled and solidified on the surface of the cooling roll to form a composite film, and then the solidified film A and the base sheet are bonded together. Film A is solidified by peeling off the sandwiched filamentous body from the base sheet to the side of Film A and Film B.
A method for producing a breathable composite sheet, the method comprising forming a fractured portion having a plurality of mutually parallel tear edges penetrating the layer B and the layer B in the thickness direction. 4. The breathable base sheet and the thermoplastic polymer film A that has just been melt-extruded from the T-die are placed between them with a number of mutually parallel filaments sandwiched between them, and then heated with a cooling roll. The molten film A is gripped and pressure-bonded with a press roll, cooled and solidified on the surface of the cooling roll to form a composite film, and then the composite film and another thermoplastic polymer immediately after being melt-extruded from a T-die. The composite film is gripped and pressed with a cooling roll and a press roll so that the solidified film A side of the composite film is in contact with the molten film C, and the molten film C is cooled on the surface of the cooling roll.
The layer of solidified film A and the layer of solidified film C are separated by solidifying and then peeling off the filament embedded in the composite film from the base sheet toward the film A and film C side. 1. A method for producing a breathable composite sheet, the method comprising forming a fractured portion having a plurality of mutually parallel tear edges passing through the sheet in the thickness direction. 5 A breathable base sheet, a large number of mutually parallel filaments, a thermoplastic polymer film A immediately after being melt-extruded from a T-die, and another preformed thermoplastic polymer film or metal foil B ′ and
The molten film A is gripped and pressed by a cooling roll and a press roll so as to be laminated in this order, and the molten film A is cooled and solidified on the surface of the cooling roll to form a composite film. Another thermoplastic polymer film freshly melt extruded
C′ and the film or metal foil of the composite film.
The molten film C' is gripped and pressed by a cooling roll and a press roll so that B' is in contact with the molten film C', and the molten film C' is cooled and solidified on the surface of the cooling roll, and then the wire embedded in the composite film is By peeling off the strip from the base sheet, a large number of mutually parallel strips penetrating the layer of solidified film A, the layer of film or metal foil B', and the layer of solidified film C' in the thickness direction are formed. 1. A method for producing a breathable composite sheet, the method comprising: forming a broken portion having a tear edge.