JPH02310031A - Heat shrinkable laminated film - Google Patents

Abstract

PURPOSE:To obtain the non-curled film excellent in adhesion, close bonding, content-property resistance, dimension stability and transparency by extrusion- laminating the thermoplastic resin having specified range of melt index on a heat shrinkable film. CONSTITUTION:An unoriented thermoplastic resin sheet 2 is brought in contact with the formed object 4 with curved surface, and is heated from the side of a heat shrinkable film. Consequently, the heat shrinkable film having been oriented is shrunk by the heat, and with this shrinkage, the phenomenon that an unoriented thermoplastic resin layer 2 enters the formed object, occurs. Especially, said effect becomes large for the curved surface. The thermoplastic resin with such large effect has MI in the range of 5-200g/10 min/190 deg.C. Especially, in the resin having MI in the range of 10-50g/10 min/190 deg.C, remarkable effect appears. By using the thermoplastic resin giving adhesion to the unoriented layer in the lower layer, the oriented film layer in the upper layer is suited to said curved surface, and becomes the layer excellent in content- property resistance as the label for in-mold.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a heat-shrinkable laminated film, and more specifically, it can be used in the fields of in-mold labels, general labels, etc., and can also be used as a lid material. Regarding heat-shrinkable film.

(Prior art) Conventionally, for the above-mentioned applications, organic solvent-based adhesives, emulsion-based adhesives, water-based adhesives, hot-melt adhesives, etc. have been applied to heat-shrinkable films for the purpose of imparting adhesive properties. A heat-shrinkable laminated film made 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, because the molecular weight of the adhesive is relatively small, the resistance to the contents against detergents, shampoos, chemicals, water, etc. is poor. There was a problem. Furthermore, since the solvent used in the adhesive is water or an organic solvent, it adversely affects the dimensional stability of the heat-shrinkable film during drying, resulting in problems such as curling. Furthermore, in the case of labels that are attached to curved surfaces, the adhesive layer needs to be thick to some extent, but in the case of adhesives other than hot melt adhesives, they are usually very thin, at 1 to 5 μm, so they do not bond well with the adherend. There was a problem that the adhesion was poor. On the other hand, in the case of a hot melt adhesive, although it is possible to increase the amount of application, there is a problem that the adhesive melts during thermocompression bonding and protrudes from the label.

When the heat-shrinkable laminated film described above is used as a lid, it has certain characteristics such as transparency, peelability (no adhesive remains on the flange of the container when the lid is removed), dimensional stability, curling, adhesion, etc. This is an important performance.

In the case of hot melt adhesives, the adhesiveness is good, but there are problems in that the peeling condition is poor and the transparency is also poor. Adhesives other than hot melt adhesives have problems such as poor adhesion, curling, and transparency.

Furthermore, the use of a stretched single film or a coextruded single film may be considered for these applications, but there is a problem in that the adhesion to the adherend is poor.

The problem to be solved by the present invention is to provide a heat-shrinkable laminated film that has excellent adhesion properties, particularly adhesion to curved surfaces, adhesion, content resistance, dimensional stability, peeling state, and transparency, and does not cause curling. It's about doing.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides Nord index (hereinafter abbreviated as MI) on a heat-shrinkable film.

) of 5 to 200 (g/10 minutes/190'C) is extruded and laminated using a laminator in an unstretched state (3%) to provide a heat-shrinkable laminated film.

Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a sectional view of a heat-shrinkable laminated film obtained by laminating a thermoplastic resin (2) on one side of a heat-shrinkable film (1) in an unstretched state using an extrusion laminator. In addition, Figure 2 is printed on heat-shrinkable film (1) (3).
FIG. 3 is a cross-sectional view of a heat-shrinkable laminated film formed by laminating a thermoplastic resin after applying a heat-shrinkable resin.

As shown in FIG. 3, the laminated film of the present invention has a molded product (4) with a curved surface and an unstretched thermoplastic resin layer (2).
) and heat it from the heat-shrinkable film side, the stretched heat-shrinkable film shrinks due to the heat.
Concomitantly, a phenomenon occurs in which the unstretched thermoplastic resin layer (2) bites into the adherend (molded product) (anchoring effect).
. This effect is particularly great for curved surfaces. Thermoplastic resins with a large effect have an Ml of 5 to 200 (g/10 min/1
90℃), especially when Ml is 10 to 5
Those in the range of 0 (g/10 minutes/190°C) appear prominently.

When a stretched single film or a coextruded film is used, the resin is oriented and the degree of crystallinity increases, resulting in poor adhesion to adherends as an adhesive film. However, a laminated film in which the upper layer is stretched and the lower layer (the layer in contact with the adherend) is unstretched can be made by using a thermoplastic resin that has adhesive properties in the lower unstretched layer.
Excellent adhesion to adherends. In particular, for a curved surface, the upper stretched film layer corresponds to the curved surface and becomes an in-mold label with excellent resistance to contents.

FIG. 4 is a cross-sectional view when used as a lid material, and the effect in this case is also obtained by the same phenomenon as in the case of a label.

That is, the upper layer heat-shrinkable film (1) shrinks by thermocompression bonding, and the unstretched thermoplastic resin (2)
corresponds to the curved surface of the adherend (flange portion of the container) and exhibits good adhesion. This lid material is transparent, peelable (no thermoplastic resin remains on the flange of the container when the lid material is removed),
It has excellent dimensional stability, curl resistance, water resistance, etc.

The heat-shrinkable film used in the present invention may be a film that has been subjected to stretching processing after film formation, and may be a film that shrinks when heated; for example, it may be made of vinyl chloride, polypropylene, polyethylene, borisdyrene, polyester, etc. Non-foamed and foamed films can be used.

The thickness of the heat-shrinkable film used in the present invention is 20 to 2
A range of 00 μm is preferred, and a range of 40-100 μm is particularly preferred.

As the thermoplastic resin used in the present invention, resins that have excellent adhesion to adherends such as glass, metal, and plastic, and excellent content resistance can be used, and have a mel I index of 5 to 200 (g /10 minutes/190°C) is preferably in the range of 10 to 50 (g/10 minutes/190°C)
Particularly preferred are those within this range. Furthermore, since the thermoplastic resin is laminated on a heat-shrinkable film in an unstretched state, the thermoplastic resin used in the present invention is preferably a resin that can be extruded and laminated at 250° C. or lower and has ductility.

Examples of thermoplastic resins include ethylene-
Examples include acrylic acid copolymer resin, ethylene-vinyl acetate copolymer resin or its acid-modified product, ethylene diacrylic acid ester copolymer resin or its acid-modified product, etc., and two or more of these resins are combined. You can also use

The thermoplastic resin used in the present invention includes an adhesive N1 agent such as rosin, rosin modified resin, terpene resin, terpene modified resin, aliphatic hydrocarbon resin, aromatic hydrocarbon resin, ketone resin, cyclized rubber; paraffin Waxes such as wax, low molecular weight polyethylene, and synthetic wax; polyethylene and modified products thereof, etc. can be added as appropriate, and auxiliary agents 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 (membrane cracking) is likely to occur during film formation, making it difficult to obtain a film with excellent content resistance and adhesion. On the other hand, if it is thicker than 200 μm, the shrinkage performance of the heat-shrinkable film cannot be achieved. This is not desirable because it tends to disappear.

(Example) Example 1 A thermoplastic resin (Diktherm E L-96, MI=17
(g/10 minutes/190℃), Dainichi Ink Chemical Industry■
crystallization) with a thickness of 25 μm and a processing temperature of 230°C, L/D = 2.
8. An in-mold label was produced using an extrusion laminator with a diameter of -40 mm.

The shrinkage rate of the label was 0% in both length and width.

When the label was used as an in-mold label for a polyvinyl chloride bottle by blow molding, it had good resistance to contents (immersion in water, detergent, and cooking oil at 40°C for 17 days) and adhesion.

Comparative Example 1 In Example 1, instead of laminating thermoplastic resin,
An in-mold label was prepared in the same manner as in Example 1, except that an organic solvent adhesive (Dick Seal M-720AH1, manufactured by Inu Nippon Ink Chemical Industry Co., Ltd.) was applied at a rate of 5 g/n.

As a result, we were able to suppress the shrinkage rate of the label to 0%, but the curling and content resistance (immersion in water, detergent, and cooking oil for 40°C and 17°F) were poor, and the label peeled off.
wait.

Example 2 A heat-shrinkable polyvinyl chloride film with a thickness of 40 μrn was coated with a thermoplastic resin (Dyxotherm EI, -95, MI
-36 (g/l, 0 min/190°C), Dainippon Ink & Chemicals Co., Ltd. (gradient product) with a thickness of 20 μm and a processing temperature of 190°C. Created. The shrinkage rate of the lid material is O in both length and width.
%Met. 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. Furthermore, when the lid of the can was removed, interfacial peeling occurred between the aluminum can and the thermoplastic resin layer, and the thermoplastic resin did not remain on the flange of the can, making it sanitary.

Comparative Example 2 In Example 2, instead of laminating the thermoplastic resin,
A lid material was produced in the same manner as in Example 2, except that a hot melt adhesive (Deink Nord DX-11C1 Dainippon Ink Chemical Industry IJ Kiku product) was applied at a rate of 20 g/rrr. As a result, we were able to suppress the shrinkage rate of the lid material to 0%, but the transparency was poor, and the peeling caused failure of the Botmel adhesive, and the Botmelt adhesive was applied to the flange of the 2-piece aluminum can. remained white.

(Effects of the Invention) When used as a label, the heat-shrinkable laminated film of the present invention has excellent contents resistance even for containers with curved surfaces. On the other hand, when used as a lid material, it has excellent adhesion and releasability, so it can be used as a top lid for juice, beer, etc. cans, and even when cooled with water, water does not get into the mouth of the container, making it easy to drink. It is very hygienic as the two lids do not need to be removed.

[Brief explanation of drawings]

Figures 1 and 2 show cross-sectional views of the heat-shrinkable laminated film of the present invention, and Figure 3 shows the heat-shrinkable laminated film of the present invention 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. ■... Heat-shrinkable film, 2... Unstretched thermoplastic resin layer, 3... Printed layer, 4... Adherent (molded product with a curved surface), 5... Adherent (flange part of container). Agent Patent Attorney Masaru Takahashi Separate volume Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. On the heat-shrinkable film, melt index is 5~5
A heat-shrinkable laminated film made by extruding thermoplastic resins in the range of 200 (g/10 minutes/190°C) and laminating them in a non-stretched state using a laminator.