JP3032982B2 - Heat shrinkable laminated film - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a heat-shrinkable laminated film, and more specifically, it can be used in fields such as in-mold labels and general labels, and can also be used as a lid material. It relates to a heat-shrinkable film.

(Prior art) Conventionally, for the above-mentioned applications, an organic solvent-based adhesive, an emulsion-based adhesive, a water-based adhesive, a hot-melt adhesive, or the like is applied to a heat-shrinkable film for the purpose of imparting adhesiveness. A heat-shrinkable laminated film formed by coating is used.

(Problems to be Solved by the Invention) When the above-mentioned heat-shrinkable laminated film is applied to the field of labels, the molecular weight of the adhesive is relatively small, so that the detergent,
There was a problem that the content resistance to shampoos, chemicals, water and the like was poor. Further, since the solvent used for the adhesive is water or an organic solvent, the dimensional stability of the heat-shrinkable film is adversely affected during drying, and there is a problem such as curling. Furthermore, in the case of a label to be attached to a curved surface, the adhesive layer needs to be thick to some extent. However, in the case of an adhesive other than the hot melt adhesive, it is usually very thin, 1 to 5 μm. Has a problem that the adhesiveness of the resin is poor.
On the other hand, in the case of a hot melt adhesive, the amount of application can be increased, but there has been a problem that the adhesive melts during thermocompression bonding and oozes out of the label.

When the above-mentioned heat-shrinkable laminated film is used as a lid material, transparency, peeling state (the adhesive does not remain on the flange of the container when the lid material is peeled off), dimensional stability, curl, adhesiveness, etc. This is an important performance. In the case of a hot melt adhesive, there is a problem that the adhesiveness is good, but the peeling state is poor and the transparency is also poor. In the case of an adhesive other than the hot melt adhesive, there has been a problem that the adhesiveness, curl and transparency are inferior.

Further, for these uses, a stretched single film or a co-extruded film may be used, but there is a problem that the adhesiveness to an adherend is poor.

The problem to be solved by the present invention is to provide a heat-shrinkable laminated film which is excellent in adhesiveness, in particular, adhesiveness to a curved surface, adhesion, resistance to contents, dimensional stability, peeled state, transparency, and curl-free. Is to do.

(Means for Solving the Problems) In order to solve the above problems, the present invention has a melt index (hereinafter abbreviated as MI) of 5 to 200 (g / 10 min / 190) on a heat-shrinkable film. C.) is provided, and a heat-shrinkable laminated film is provided by laminating a thermoplastic resin in a non-stretched state using an extruding laminator.

 Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view of a heat-shrinkable laminated film obtained by laminating a thermoplastic resin (2) in an unstretched state on one side of a heat-shrinkable film (1) using an extruder laminator. FIG. 2 is a cross-sectional view of a heat-shrinkable laminated film formed by printing (3) on a heat-shrinkable film (1) and then laminating a thermoplastic resin.

The laminated film of the present invention is stretched by bringing a non-stretched thermoplastic resin layer (2) into contact with a molded product (4) having a curved surface as shown in FIG. 3 and heating from the heat-shrinkable film side. The heat-shrinkable film that has been shrunk by heat causes a phenomenon in which the unstretched thermoplastic resin layer (2) digs into the adherend (molded product) (anchor effect). This effect is particularly large for curved surfaces. A thermoplastic resin with a large effect has a MI of 5-200 (g / 10 minutes / 190 ° C)
In particular, MI is 10 to 50 (g / 10 minutes / 190
C.) is remarkably exhibited.

When a stretched single film or co-extruded film is used, the orientation of the resin is increased and the crystallinity is increased, so that the adhesiveness of the adhesive film to the adherend is poor. However, the laminated film in which the upper layer is stretched and the lower layer (the layer in contact with the adherend) is not stretched has a lower adhesiveness to the adherend by using a thermoplastic resin having an adhesive property to the lower unstretched layer. Excellent. In particular, for a curved surface, the upper stretched film layer corresponds to the curved surface, and as a label for in-mold, it has excellent content resistance.

FIG. 4 is a cross-sectional view when used as a cover material, and the effect in this case is also obtained by the same phenomenon as that of the label. That is, the film (1) that contracts due to the heat of the upper layer contracts by thermocompression bonding, and the unstretched thermoplastic resin (2) accompanies the curved surface (the flange portion of the container). Shows adhesion. This lid material is excellent in transparency, peeling state (no thermoplastic resin remains on the flange of the container when the lid material is peeled off), dimensional stability, curl, water resistance and the like.

The heat-shrinkable film used in the present invention is a film that has been subjected to a stretching process after film formation and may be any film that shrinks by heating, and includes, for example, vinyl chloride, polypropylene, polyethylene, polystyrene, polyester, and the like. Non-foamable and foamable films can be used.

The thickness of the heat-shrinkable film used in the present invention is 20 to 20.
The range of 0 μm is preferred, and the range of 40 to 100 μm is particularly preferred.

As the thermoplastic resin used in the present invention, a resin having excellent adhesion to an adherend such as glass, metal, and plastic and having excellent content resistance can be used, and has a melt index of 5 to 200 (g / 10 Min / 190 ° C.), and particularly preferably in the range of 10 to 50 (g / 10 min / 190 ° C.). Further, the thermoplastic resin used in the present invention is preferably a resin which can be extruded and laminated at 250 ° C. or lower and has spreadability because of the lamination in a non-stretched state on the heat-shrinkable film.

Examples of such a thermoplastic resin include, for example, an ethylene-acrylic acid copolymer resin, an ethylene-vinyl acetate copolymer resin or an acid-modified product thereof, an ethylene-acrylic acid ester copolymer resin or an acid-modified product thereof, and the like. And two or more of these resins may be used in combination.

To the thermoplastic resin used in the present invention, rosin, rosin-modified resin, terpene resin, terpene-modified resin, aliphatic hydrocarbon resin, aromatic hydrocarbon resin, ketone resin, tackifiers such as cyclized rubber; paraffin wax; Waxes such as low molecular weight polyethylene and synthetic wax; polyethylene and modified products thereof can be appropriately added, and auxiliaries such as antioxidants, slip agents and antiblocking agents can also be added.

The thickness of the thermoplastic resin layer is preferably in the range of 8 to 200 μm. If the thickness is less than 8 μm, pinfall (film cracking) is likely to occur during film formation, and it is difficult to obtain a material having excellent content resistance and adhesiveness. On the other hand, if the thickness is more than 200 μm, the heat shrinkable film exhibits shrinkage performance. It is not preferable because it tends to disappear.

(Example) Example 1 A thermoplastic resin (Dicktherm EL-96, MI = 17 (g / 10 min / 1) was applied to a heat-shrinkable polypropylene film having a thickness of 80 μm.
90 ° C), Dainippon Ink and Chemicals Co., Ltd.
m, a processing temperature of 230 ° C., an in-mold label was produced with an extrusion laminator having an L / D of 28 and a diameter of 40 mmφ. The shrinkage of the label was 0% in both the vertical and horizontal directions. As a result of using the label as an in-mold label for a polyvinyl chloride bottle by blow molding, both the content resistance (immersion in water, detergent, and edible oil at 40 ° C. for 7 days) and adhesiveness were good.

Comparative Example 1 In Example 1, except that a thermoplastic resin was laminated, an organic solvent-based adhesive (Dick Seal M-720AH, a product of Dainippon Ink and Chemicals, Inc.) was applied at a ratio of 5 g / m ^2. Produced an in-mold label in the same manner as in Example 1.

As a result, the shrinkage of the label could be suppressed to 0%, but the curl and the content resistance (immersion in water, detergent and edible oil at 40 ° C. for 7 days) were inferior, and the label was peeled off.

Example 2 A thermoplastic resin (Dicktherm EL-95, MI = 36 (g / 10 min / 1) was applied to a polyvinyl chloride heat-shrinkable film having a thickness of 40 μm.
90 ° C), Dainippon Ink and Chemicals Co., Ltd.
m, L / D = 28 at a processing temperature of 190 ° C., and a lid material was prepared with an extruder laminator having a diameter of 40 mmφ. The shrinkage of the lid is
The height and width were 0%. The lid material was thermocompression-bonded to the flange of a two-piece aluminum can and immersed in water for one week, but no water leakage occurred. In addition, when the lid of the can was peeled off, interface peeling occurred between the aluminum can and the thermoplastic resin layer, and the thermoplastic resin was not left on the flange of the can, which was hygienic.

Comparative Example 2 Example 2 was repeated except that a hot melt adhesive (Dick Melt DX-11C, a product of Dainippon Ink and Chemicals, Inc.) was applied at a rate of 20 g / m ² instead of laminating a thermoplastic resin. In the same manner as in Example 2, a lid member was produced. As a result, the shrinkage of the lid material could be suppressed to 0%, but the transparency was inferior, and the peeling caused cohesive failure of the hot melt adhesive, and the hot melt adhesive was applied to the flange of the aluminum two-piece can. It remained white.

(Effect of the Invention) The heat-shrinkable laminated film of the present invention has excellent content resistance even for a container having a curved surface in the case of label use. On the other hand, in the case of lid materials, the adhesiveness and peeling state are excellent, so it can be used as an upper lid for cans of juice, beer, etc., even if cooled with water, water does not enter the drinking mouth of the container,
When drinking, it is very hygienic because the top cover is peeled off.

[Brief description of the drawings]

FIGS. 1 and 2 show cross-sectional views of the heat-shrinkable laminated film of the present invention, and FIG. 3 shows that the heat-shrinkable laminated film of the present invention is applied as an in-mold label on a molded product having a curved surface. FIG. 4 is a cross-sectional view when the heat-shrinkable laminated film of the present invention is applied as a lid material. 1 ... heat-shrinkable film, 2 ... unstretched thermoplastic resin layer, 3 ... print layer, 4 ... adherend (molded product having a curved surface), 5 ... adherend (flange part of container) ).

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI B29L 31:56

Claims (1)

(57) [Claims] An extruded thermoplastic resin having a melt index in the range of 5-200 (g / 10 min / 190 ° C.) is laminated on a heat-shrinkable film in a non-stretched state using a laminator. Shrinkable laminated film.