JPH0431504B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a thermoformable packaging material that is most suitable as a food packaging material for distribution of fresh foods such as seafood, meat, fruits, and vegetables, and a method for producing the same. [Background technology and its problems] Conventionally, packaging materials for fresh foods include trays made of thermoformed foam sheets and resin sheets, and improvements to these materials to provide cushioning and water retention properties.
The bottom of a resin sheet container is covered with shredded foam sheets, paper, or wood as a water-retaining material, and the resin sheet is extruded and laminated with nonwoven fabric, blotting paper, foam material, etc. It is used. However, with these conventional methods, workability is poor when a foam sheet or the like is laid or fixed on the bottom of the container, and when extrusion lamination is used, there are problems with adhesion. Since the foam material layer and the sheet layer are limited to the same resin, the types of water-retaining members that can be used and, by extension, the uses of the packaging material are limited. Furthermore, in conventional examples, when a container having a predetermined shape is formed by thermoforming using a packaging material having a foam layer, the foam layer melts due to the heating of the packaging material, reducing the buffering effect and water retention effect. The disadvantage is that it cannot be obtained. In addition, in the case of extrusion laminate, when the resin sheet is thin, laminates such as non-woven fabric and blotting paper appear on the back side of the sheet, making thermoforming difficult, and even if thermoforming is possible, the commercial value of the thermoformed product is and becomes impractical. In particular, when laminating a resin sheet with a film or nonwoven fabric made of a resin different from the sheet, it is necessary to perform a surface treatment such as oxidation treatment and then engage the resin sheet with an anchor effect, which is a complicated process. ,
It is virtually impossible to laminate a nonwoven fabric or the like with a thin sheet. Moreover, when laminating non-woven fabrics, absorbent paper, etc., these films and resin sheets are strongly engaged due to the anchor effect, so when thermoforming into a container-like object, the absorbent paper, etc. may crack or crack. There is a problem that it breaks. [Object of the Invention] The object of the present invention is to provide a packaging material for thermoforming that can be easily molded without causing cracks in the water-retaining member during thermoforming even when a resin sheet is laminated to the water-retaining member, and the production thereof. The purpose is to provide a method. [Means and effects for solving the problems] The present invention provides a water-retaining member made of multiple layers of paper bonded to each other by, for example, needle punching;
A film-like member made of a first resin is bonded to this water-retaining member via an adhesive and forms a composite film together with the water-retaining member, and a second film-like member is laminated with this film-like member and is soluble in the first resin. It is constructed by comprising a resin sheet made of resin. As a result, the water-retaining member is not engaged with the film-like member of the first resin due to the anchor effect, so it is highly flexible even when thermoforming trays, etc., without impairing thermoformability. The above objective can be achieved. The method for manufacturing a thermoforming packaging material of the present invention includes laminating a water-retentive member and a film-like member made of a first resin via an adhesive by dry lamination, wet lamination, etc., and then laminating the film-like member made of the first resin. A shaped member and a resin sheet made of a second resin that is compatible with the member are extrusion laminated. [Example] Hereinafter, an example of the present invention will be described based on the drawings. FIG. 1 shows an embodiment of a thermoformable packaging material according to the present invention. In FIG. 1, a film-like member 1 made of a first resin is bonded to a water-retentive member 10 such as paper shown at the top position through an adhesive 6 by dry lamination or wet lamination. A composite film 12 is thus formed. A resin sheet 20 made of a second resin that is compatible with this first resin is extrusion laminated onto the film-like member 1 made of a first resin of this composite film 12, and the composite film 12 and the resin sheet 20 are extrusion laminated. A thermoforming packaging material 22 is thus formed. Here, the water-retaining member 10 is a material having water-retaining properties such as paper such as absorbent paper, synthetic or natural nonwoven fabric, or open-cell foam sheet.
The thickness used is 50 μm to 5 cm. In this case, in the case of paper such as blotting paper, a plurality of layers may be needle-punched and partially locked or joined. In addition, the nonwoven fabric may be either long or short fiber, and preferably has hydrophilic properties or has been subjected to hydrophilic treatment. Further, the film-like member 1 made of the first resin is
The type of resin used is polyolefin (PO), polystyrene (PS), polyamide, polyethylene terephthalate (PET), polycarbonate (PC), etc., and the thickness of the film is 10 to 1000 μm, preferably 10 to 500 μm, more preferably, Ten~
It is 100 μm. Moreover, the adhesive 6 is vinyl acetate,
Vinyl resins such as vinyl chloride, cellulose resins such as nitrocellulose and ethyl cellulose, copolymers of synthetic rubber and acrylic resins, urethane resins, epoxy resins, etc. are used, and the types are not particularly limited, but Preferably, those used for food, such as urethane and acrylic. Further, the resin sheet 20 made of the second resin has a thickness of 100 μm to 3 mm, preferably 200 μm to 2 mm.
mm, and the type of resin is PO, PET,
PS, high impact polystyrene (HIPS), vinyl chloride, etc. can be selected as appropriate depending on the application, and are said to be compatible with the first resin. Note that the second resin may contain an inorganic filler or various additives. Next, an embodiment of the manufacturing method according to the present invention will be described with reference to FIGS. 2 and 3. FIG. 2 shows a schematic configuration of an apparatus for performing dry lamination among the apparatuses used to carry out the manufacturing method according to the present invention. In FIG. 2, a rubber roll 3 and a gravure roll 4 are provided on one side of a roll 2 around which a film-like member 1 made of a first resin is wound, and this gravure roll 4 is housed in a pan 5. adhesive 6
The film-like member 1 is inserted between these rolls 3 and 4, and an adhesive 6 is applied to one side of the film-like member 1. A drying section 7 is provided downstream of the rolls 3 and 4, and the adhesive 6 applied to the film member 1 inserted between the rolls 3 and 4 is dried. A rubber roll 8 and a steel roll 9 are provided on the downstream side of the drying section 7, while a roll 11 on which a water-retaining member 10 is wound is provided on the upper right side of these rolls 8 and 9 in the figure. roll 8,9
When the film-like member 1 and the water-retaining member 10 are inserted through the adhesive 6, the film-like member 1 and the water-retaining member 10 are pressed together to form a composite film 12. film 12
is wound into a composite material roll 13. FIG. 3 shows a composite film 12 and a resin sheet 20 formed by the apparatus shown in FIG.
A schematic configuration of an apparatus for extrusion lamination is shown, and a thermoforming packaging material 22 is formed by this apparatus. In FIG. 3, the composite material roll 13 is supported in the delivery section 14, and on one side of the composite material roll 13, a pair of pressure rolls 15 and a cooling roll 16 are provided at a temperature of 100°C to 250°C. , the composite material film 12 unwound from the composite material roll 13 is passed through the guide roll 17 so that the water retaining member 10 side is connected to the pressure roll 15 and the film-like member 1 side is connected to the cooling roll 1.
It is inserted between both rolls 15 and 16 so as to face 6. Here, the cooling roll 16 also acts as a pressure roll. On the other hand, an extrusion molding machine 30 is arranged above the pressure roll 15 and the cooling roll 16, and this extrusion molding machine 30 has a hopper 1 into which the second resin material is introduced.
8. It is composed of an extruder 19 that heats and melts this second resin at 190°C to 280°C, and a die 21 that extrudes a resin sheet 20 made of the second resin between a pressure roll 15 and a cooling roll 16. The resin sheet 20 extruded from the die 21 is formed into a composite film 1
The thermoformable packaging material 22 is laminated onto the film-like member 1 side of the film member 2 and cooled by pressing between a pressure roll 15 and a cooling roll 16. The packaging material 22 formed by laminating the composite film 12 and the resin sheet 20 is wound up by the winding section 24 via the guide roll 23.
This becomes a packaging material roll 25. In addition, packaging material roll 2
The packaging material 22 wound up into 5 is thermoformed by a molding device (not shown) to form a container of a predetermined shape. According to this embodiment, the water retaining member 10
When extrusion laminating the resin sheet 20, the film-like member 1 which is compatible with the resin sheet 20 was previously laminated on the water-retaining member 10 by a dry lamination method. Without being limited by the material, even if the water-retaining member 10 is made of a resin different from the resin sheet 20, such as a nonwoven fabric or a foam layer, the resin sheet 20 can be laminated with sufficient adhesive strength. becomes possible. Therefore, without changing the resin of the resin sheet 20, it is possible to select the water-retaining member 10 suitable for the object to be packaged. For this reason, for example, resin sheet 2
If a water-retaining member 10 such as a foam material having a higher softening temperature is dry-laminated with a film member 1 that is compatible with the resin sheet 20 and then extrusion laminated, the air bubbles in the water-retaining member 10 will be removed during thermoforming. Since it does not melt and bond with heat, it is possible to maintain high water retention and cushioning properties. Therefore, since it has excellent water retention, it is possible to maintain the freshness of fresh foods and improve their suitability for sale, and because it has excellent buffering properties, it is possible to improve the protection of fresh foods, which in turn improves their suitability for distribution. be able to. Moreover, in this embodiment, since the water-retaining member 10 is bonded to the film-like member 1 via the adhesive 6, it is highly flexible, and even during thermoforming, the water-retaining member 10 will not be damaged or cracked. Never.
Furthermore, since it has a so-called three-layer structure, the water-retentive member 10 does not appear on the back surface of the resin sheet 20, resulting in a good appearance and improved commercial value.
In addition, if the water-retaining member 10 is made of multiple layers of needle-punched paper, even if the absorbent paper is weak in strength, the fibers can be intertwined to achieve the desired strength and thickness. It is possible to improve the quality of the product. Next, a table of experimental results confirming the effects of this example is described below. Here, in each comparative example, other conditions were the same as in the experimental examples of the present invention, except that the film-like member 1 made of the first resin was not used.

〔Effect of the invention〕

According to the present invention as described above, even if a resin sheet is laminated to a water-retaining member, the water-retaining member can be easily molded without causing cracks or the like during thermoforming.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of the thermoforming packaging material of the present invention, FIG. 2 is a schematic configuration diagram of a dry laminate used to carry out an embodiment of the manufacturing method of the present invention, and FIG. The figure is a schematic diagram of the extrusion laminate used to carry out the above embodiment. 1... Film-like member made of first resin, 6...
... Adhesive, 10 ... Water-retaining member, 12 ... Composite film, 15 ... Pressure roll, 16 ... Cooling roll that acts as a pressure roll, 20 ... Resin sheet made of second resin, 22 ... Heat Packaging material for molding, 30...extrusion molding machine.

Claims (1)

[Claims] 1. A composite film is formed including a water-retaining member and a film-like member made of a first resin bonded to the water-retaining member via an adhesive, and 1 The resin film-like member side is the first
A packaging material for thermoforming, characterized in that it is laminated with a resin sheet made of a second resin that is compatible with the resin. 2. The thermoforming packaging material according to claim 1, wherein the water retaining member is a plurality of layers of paper bonded together by needle punching. 3. A water-retaining member and a film-like member made of a first resin are laminated via an adhesive to form a composite film, and the film-like member made of the first resin of the composite film has a bond with the first resin. A method for producing a thermoforming packaging material, which comprises extrusion laminating a resin sheet made of a soluble second resin. 4. In claim 3, extrusion lamination is performed at a temperature of 100°C to 250°C between a resin sheet of the second resin extruded from an extrusion molding machine and a composite film using a pressure roll. A method for producing a packaging material for thermoforming, characterized by: