JP3087179B2 - Packaging material with easy-open resin layer - Google Patents

Description

The present invention relates to a packaging material having an easily-openable resin layer.

[Conventional technology]

2. Description of the Related Art A packaging material used as a lid material for sealing a container made of, for example, expanded polystyrene, which can be peeled off when the sealed container is opened, has been developed.
Generally, such a packaging material has an easy-open resin layer on a surface to be fused to a container or the like. FIG. 6 is a schematic sectional view showing an example of a conventional packaging material. In FIG. 6, the packaging material 70 is the paper layer 7
1. It has a multilayer structure in which a polyethylene resin layer 72, an aluminum foil layer 73, an anchor coat agent layer 74, a polyethylene resin layer 75, and an easily-openable resin layer 76 are laminated. Usually, such a packaging material 70 having a multilayer structure is formed by first laminating paper and aluminum foil via a polyethylene resin to form a paper layer 71, a polyethylene resin layer 72, and an aluminum foil layer 73.
A base sheet made of is formed, and an anchor coat agent layer 74 is provided on the aluminum foil layer 73 of the base sheet. Then, after the polyethylene resin is sand-laminated on the above-mentioned base sheet, the easy-opening resin is extruded and laminated.

[Problems to be solved by the invention]

However, in the above-described packaging material, the anchor coat agent layer 74 is used.
The easy-opening resin layer 76 is not provided directly, but the easy-opening resin layer 76 is formed via the polyethylene resin layer 75.
There has been a problem that the number of processes for manufacturing the packaging material increases and the production cost increases. This was because the polyethylene resin layer 75 had to be interposed due to the characteristics of the easy-opening resin. That is, the lamination strength of the extruded laminate tends to be improved by increasing the heat-melting temperature of the extruded resin to promote the oxidation of the resin. 330
℃), pyrolysis occurs, and usually requires extrusion lamination at about 230 ° C. For this reason, the surface-opening degree of the easily-openable resin layer extruded and laminated on the anchor coat agent layer is low and the lamination strength is insufficient, so that it cannot be put to practical use. Further, additives such as a tackifier contained in the easily-openable resin layer bleed to the interface with the anchor coat agent layer, so that the isocyanate-based curing agent before the crosslinking and curing reaction in the anchor coat agent and the bleed. There is also a problem that a sufficient adhesive strength between the aluminum foil layer and the easily-openable resin layer cannot be obtained due to the reaction with the added additive. Therefore, it was necessary to make the structure as shown in FIG. However, because the packaging material has such a configuration,
When the formed paper layer 71, polyethylene resin layer 72, the base sheet composed of the aluminum foil layer 73 is in a roll state,
Printing surface ink and aluminum foil layer provided on paper layer 71
The contact of the aluminum foil 73 with the aluminum foil 73 causes contamination of the aluminum foil layer 73, and there is also a problem that lamination failure easily occurs between the aluminum foil layer and the easy-open resin layer.

The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide a packaging material having a high laminate strength between a base sheet having a barrier layer and an easily-openable resin layer, and which is easy to manufacture. Aim.

[Means for solving the problem]

In order to achieve this object, the present invention provides a packaging material having at least a base sheet having a barrier layer and an easy-open resin layer formed on the base sheet via an adhesive layer, wherein the adhesive layer Is an anchor coat agent layer, and the surface tension of the easy-opening resin at 220 ° C. on the surface of the easy-opening resin containing the tackifier in a molten thin film state is 3
0 dyn / cm or more, so that it is formed by directly extruding and laminating the anchor coating agent layer of the base sheet while injecting an ozone-containing gas, and further, fine irregularities are formed on the surface by a gravure screen. The easy-opening resin was extruded and laminated by using the formed cooling roll, and a plurality of minute irregularities formed at the same time as being formed were provided on the surface of the easy-opening resin layer.

[Action]

The easy-open resin melted from the T-die and extruded into a thin film is injected with an ozone-containing gas, and at least a base sheet having a barrier layer and the above-mentioned easy-open resin are laminated via an anchor coat agent layer. Then, a packaging material is formed. For this reason, since the easily-openable resin is laminated on the anchor coat agent layer in a state where the ozone-containing gas is jetted and the surface is oxidized, high lamination strength is obtained.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

 FIG. 1 is a schematic sectional view of a packaging material according to the present invention.

In FIG. 1, a packaging material 1 has a base sheet 2 and an easy-open resin layer 3, and the base sheet 2 includes a paper layer 4, a polyethylene resin layer 5, an aluminum foil layer 6, and an anchor as an adhesive layer. It is composed of a coating agent layer 7 and has a five-layer structure as a whole.

The thickness of the easily-openable resin layer 3 of the packaging material 1 is 12 to 50.
μm, preferably about 15 to 35 μm. If the thickness of the easily-openable resin layer 3 is less than 12 μm, sufficient heat sealing properties will not be exhibited, and if it exceeds 50 μm, the easily-openable resin will protrude during sealing and the cost will increase. As the easily-openable resin, generally, a polypropylene resin, a linear low-density polyethylene resin, an ethylene-vinyl acetate copolymer, an ethylene-acrylate copolymer, an ethylene-acrylic acid copolymer, and a modified product thereof ( Unsaturated carboxylic acid copolymers, graft copolymers, etc.) or a mixture of the above resins. In addition, rosin-based, terpene-based, petroleum resin-based, alkylphenol-based, xylene-based tackifiers, lubricants, anti-blocking agents, and the like may be added to the easily-openable resin. Then, which easy-opening resin is selected from the above-described easy-opening resins can be determined according to the material of the object to be sealed in which the packaging material is heat-sealed. Examples of the objects to be sealed include foamed materials such as polyvinyl chloride, polypropylene, polystyrene, and polyethylene terephthalate, and molded containers for sheets.

In the base sheet 2, the paper layer 4 forms the front surface of the packaging material 1, and is subjected to printing and decorative processing. Normally, high-quality paper, kraft paper, coated paper, art paper, and the like are used. The basis weight of each of these papers is preferably about 30 to 100 g / m ² . The polyethylene resin layer 5 functions as an adhesive layer between the paper layer 4 and the aluminum foil layer 6, and general-purpose low-density polyethylene is generally used. The thickness of the polyethylene resin layer 5 is about 10 to 30 μm. The aluminum foil layer 6 is used to give the packaging material 1 a gas barrier property. As the aluminum foil, a soft aluminum foil of usually about 6 to 15 μm is used. Further, the anchor coating agent layer 7 is formed by applying a urethane anchor coating agent at an application amount of 0.1 to 1.0 g / m ² . In the present invention, the base sheet 2 is not limited to the above-described one. For example, various types of biaxially stretched films (thickness of about 6 to 75 μm) in which aluminum is deposited instead of aluminum foil as a barrier layer May be used. The lamination of the paper layer 4 and the aluminum foil layer 6 may be performed by dry lamination using a urethane-based adhesive without using the polyethylene resin layer 5.

Further, instead of the paper layer 4, biaxially stretched polyester, biaxially stretched polypropylene, biaxially stretched nylon, biaxially stretched cellophane, or a laminate thereof can be used. Next, the production of the packaging material shown in FIG. 1 will be described with reference to FIG. 2 to FIG. FIG. 2 is a schematic view of a tandem extrusion laminator for manufacturing the packaging material of the present invention, and FIGS. 3 and 4 are schematic cross-sectional views of the packaging material of the present invention in the course of manufacturing.

In FIG. 2, tandem extrusion laminators 10 are T dies 11, 15 for extruding a molten resin into a thin film.
Rolls 12a, 16a and nip rolls 12b, 16b for pressing / cooling and laminating the molten thin film resin extruded from the T dies 11, 15 and the supplied sheet, and a cooling roll 12a and nip roll It has unwinders 17a and 17b for supplying between 12b and a winder 18 for winding the formed packaging material. T die 1
There is no particular limitation for 1,15, and an ordinary T die for molding a synthetic resin sheet can be used. Then, while the molten thin film resin extruded from the T die 15 reaches the cooling roll 16a and the nip roll 16b, an injection nozzle 19b for injecting an ozone-containing gas to the molten thin film resin extruded from the T die 15 is provided. The ozone generator 19a is connected to the injection nozzle 19b.

In such a tandem type extrusion laminator 10, the packaging material 1 is manufactured as follows. First, T-die 11
The polyethylene resin 21 is melted and extruded in a thin film form, and the paper sheet 23 is supplied from the unwinder 17a, and the aluminum foil 25 is supplied from the unwinder 17b, and pressed and cooled by the cooling roll 12a and the nip roll 12b. Thus, a laminate sheet 26 constituting the base sheet 2 is formed. FIG. 3 is a schematic sectional view of the laminate sheet 26. The laminate sheet 26 includes a paper layer 4, a polyethylene resin layer 5, and an aluminum foil layer 6. And this laminate sheet 26 is a coating unit
In 13, the aluminum foil layer 6 is coated with the anchor coating agent, and dried in the drying unit 14 to form the base sheet 27 (FIG. 4) on which the anchor coating agent layer 7 is formed. Next, the easy-open resin 28 is melted and extruded into a thin film from the T-die 15, and the ozone-containing gas supplied from the ozone generator 19a is injected into the molten easy-open resin 28. Injected from the nozzle 19b. The injection of the ozone-containing gas to the easily opened resin 28 in the molten state is intended to oxidize the surface of the easily opened resin 28. Then, as a measure of the surface oxidation, the interface surface tension of the ozone-containing gas injection surface of the easily-openable resin at 220 ° C. is set to 30 dyn / cm or more, preferably 35 dyn / cm or more. In order to perform such surface oxidation, ozone-containing gas air-based gas and ozone concentration 1 g / m ³ or more, a mixed gas, such as preferably 2 to 20 g / m ³ approximately.
Such an ozone-containing gas may further contain an inert gas such as a nitrogen gas. Preferably, the ozone-containing gas is injected at a flow rate of 50 to 500 ml / m ³ per minute.
Further, the ozone-containing gas may be injected in a state where the ozone-containing gas is pre-heated in a range from room temperature to 80 ° C. On the other hand, the above-mentioned base sheet 27 on which the anchor coat agent layer 7 is formed
a between the nip roll 16b and the cooling roll 16a
The base sheet 27 and the easily openable resin 28 in the molten state are pressed and cooled by the nip roll 16b to form the packaging material 1 having a laminated structure shown in FIG.

In the present invention, as described above, the easily-openable resin in the molten state
28 is sprayed with an ozone-containing gas to oxidize the surface, and is laminated with the anchor coat agent layer 7 of the base sheet 27 in this state. Good lamination is achieved. Further, the curing of the anchor coating agent layer 7 is accelerated, and additives such as a tackifier contained in the easily-openable resin layer bleed and react with the isocyanate-based curing agent in the anchor coating agent before the crosslinking curing reaction. Is effectively prevented.

The packaging material of the present invention may have a plurality of minute irregularities formed on the easily-openable resin layer. FIG. 5 is a schematic sectional view of such a packaging material, in which a packaging material 61 is composed of a base sheet 62 and an easy-open resin layer.
The base sheet 62 includes a paper layer 64, a polyethylene resin layer 65, an aluminum foil layer 66, and an adhesive layer 67, and has a five-layer structure as a whole. And an easy-open resin layer
A plurality of minute and regular irregularities 68 are formed on the surface of 63.

When the adhesive layer 67 is an anchor coating agent layer and the easily-openable resin layer 63 is formed by extruding and laminating the anchor-coating agent layer 67, the plurality of irregularities 68 are formed in the easily-opening resin layer.
It is formed simultaneously when extruding and laminating 63. That is, in FIG. 2, the irregularities 68 can be formed by using the cooling roll 12a in which a large number of minute irregularities are formed in an endless pattern by etching using a gravure screen on the peripheral surface. In this case, the gravure screen to be used may be a known one, and the number of lines is 1
Preferably less than 200 lines per inch.

As described above, since the packaging material 61 has a plurality of minute irregularities 68 on the surface of the easily-openable resin layer 63, when a large number of packaging materials 61 are overlapped, an air layer is formed between the overlapping packaging materials to form a packaging. The slipperiness between the materials is improved.

Next, the present invention will be described in more detail with reference to experimental examples.

(Experimental example) In the tandem-type extrusion laminator shown in FIG. 2, the following materials were used for extrusion lamination under the following extrusion conditions, and the packaging material having the laminated structure shown in FIG. 1 in one step (sample-1) Was manufactured.

・ Paper: Special co-morant (7
9.1 g / m ² , manufactured by Fuji Koji Paper Co., Ltd. ・ Aluminum foil: Soft aluminum foil (thickness 7 μm,
(Showa Aluminum Co., Ltd.) ・ Polyethylene resin: Low density polyethylene M-11P (Mitsui Petrochemical Co., Ltd.) ・ Anchor coating agent: Urethane-based anchor coating agent AD50
6X / CAT10 (Toyo Morton Co., Ltd.)-Easy-open resin: Ethylene-vinyl acetate copolymer resin (Peel Resin V606, Mitsui Petrochemical Co., Ltd.)-Extrusion conditions for polyethylene resin Screw L / D = 28 Cylinder temperature = 140 ° C, 230 ° C, 300 ° C, 320 ° C Adapter temperature = 320 ° C T-die temperature = 320 ° C Laminate thickness = 15μm Cooling roll temperature = 4 ° C · Extruding conditions for easy-opening resin Screw L / D = 28 Cylinder temperature = 100 ° C, 160 ° C, 200 ° C, 220 ° C Adapter temperature = 220 ° C T-die temperature = 220 ° C Laminate thickness = 25μm Cooling roll temperature = 4 ° C ・ Ozone-containing gas injection conditions: Base gas = air Ozone concentration = 3.0g / m ³ flow rate = 80 ml / m ² / min Interfacial surface tension of easy-opening resin = 36 dyn / cm For comparison, a packaging material (comparative sample) as shown in FIG. 6 was produced according to a conventional method. The lamination conditions in the step of preparing a base sheet composed of a paper layer, a polyethylene resin layer and an aluminum foil layer, the conditions for providing an anchor coat agent layer on the aluminum foil layer of the base sheet, and the materials used were the same as those of the sample described above. The same as -1. The conditions for extruding the polyethylene resin layer interposed between the anchor coat agent layer and the easily-openable resin layer and the conditions for extruding the easily-openable resin (without spraying an ozone-containing gas) were as follows. For other materials, sample-1
And the same.

・ Polyethylene resin extrusion conditions Screw L / D = 28 Cylinder temperature = 140 ° C, 220 ° C, 300 ° C, 320 ° C Adapter temperature = 320 ° C T-die temperature = 320 ° C Laminate thickness = 15μm Cooling roll temperature = 4 ° C ・ Easy opening Extrusion conditions for conductive resin Screw L / D = 28 Cylinder temperature = 100 ° C, 160 ° C, 200 ° C, 220 ° C Adapter temperature = 220 ° C T-die temperature = 220 ° C Laminate thickness = 25μm Cooling roll temperature = 4 ° C (1) The comparative sample was heat-sealed in a polystyrene foam container via an easy-open resin layer, and then each sample was peeled off. In each case, delamination between the aluminum foil layer of the packaging material and the easy-open resin layer was performed And good releasability was exhibited. That is, although the packaging material of the present invention, Sample-1, was formed in one step, it was proved that the lamination attitude of the easily-openable resin layer was sufficiently high.

In addition, the manufacturing method of the packaging material of the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist thereof.

〔The invention's effect〕

As is apparent from the above, according to the present invention, the packaging material is such that an ozone-containing gas is jetted and the easily fusible resin in a surface oxidized state is laminated to the base sheet via the anchor coat agent layer. Unreacted reaction between an additive such as a tackifier contained in the easily-openable resin layer and the anchor coating agent does not occur.
As a result, sufficient lamination strength between the base sheet and the easily-openable resin layer can be obtained, and the production process can be significantly shortened.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of the packaging material of the present invention, FIG. 2 is a schematic view of a tandem extrusion laminator for producing the packaging material of the present invention, and FIGS. 3 and 4 are shown in FIG. FIG. 5 is a schematic sectional view of a packaging material in the course of manufacturing, FIG. 5 is a schematic sectional view showing another embodiment of the packaging material according to the present invention, and FIG. 6 is a schematic sectional view of a conventional packaging material. DESCRIPTION OF SYMBOLS 1 ... Packaging material 2 ... Base sheet 3 ... Easy-open resin layer 4 ... Paper layer 5 ... Polyethylene resin layer 6 ... Aluminum foil layer 7 ... Anchor coating agent layer 10 ... tandem extrusion laminator, 11,15 ... T die, 12a, 1
6a: Cooling roll, 12b, 16b Nip roll, 17b, 17b
…… Unwinder, 18 …… Winder, 68 …… Unevenness.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI // B65D 65/40 B65D 65/40 A B29L 9:00 (72) Inventor Akihiko Nakamura 1-chome, Ichigaya-Kagacho, Shinjuku-ku, Tokyo No. 1 Dai Nippon Printing Co., Ltd. (72) Inventor Kazuhiro Nagata 1-1-1, Ichigaya Kagamachi, Shinjuku-ku, Tokyo Dai Nippon Printing Co., Ltd. (56) References JP-A-60-30338 (JP, A JP-A-60-239238 (JP, A) JP-A-2-50335 (JP, U) JP-A-6-172037 (JP, U) JP-B-61-27180 (JP, B2) JP-B-2-2 8890 (JP, B2) Japanese Patent Publication No. 61-35938 (JP, B2) Japanese Utility Model Publication No. 62-7480 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 59/04 B32B 1 / 00-35/00 B65D 65/40

Claims (2)

(57) [Claims] 1. A packaging material having at least a base sheet having a barrier layer and an easy-open resin layer formed on the base sheet via an adhesive layer, wherein the adhesive layer is an anchor coat agent layer. Injection of an ozone-containing gas onto the surface of the easy-opening resin containing the tackifier in the form of a molten thin film so that the interface surface tension of the easy-opening resin at 220 ° C. of the injection surface becomes 30 dyn / cm or more. A packaging material having an easy-opening resin layer formed by directly extruding and laminating the anchor coat agent layer of the base sheet. 2. A plurality of fine irregularities formed simultaneously with extruding and laminating the easy-opening resin using a cooling roll having fine irregularities formed on the surface thereof by a gravure screen are formed on the surface of the easy-opening resin layer. The packaging material having an easy-open resin layer according to claim 1, wherein the packaging material is provided.