JPH074190Y2 - Hollow container with label - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of use) The present invention relates to a hollow container with a label, and more specifically, a label-filled hollow container formed on the outer surface of a hollow container formed by blow molding of plastic by in-mold label operation. The present invention relates to a labeled hollow container to which a label having no adhesion such as wrinkles and having excellent adhesiveness is attached.

(Prior Art) Affixing a label for displaying contents to a hollow molded container has an important meaning in packaging technology because it enhances the commercial value of a packaging product and motivates consumers to purchase.

It has been known for a long time to label a hollow molding container with an in-mold label operation, and the label to be attached to the inner surface of the cavity of the molding die is held by means such as vacuum suction, A means for hollow molding a plastic parison is generally adopted (see, for example, JP-A-61-20281).
No. 8 bulletin).

Also, as a plastic label, a solid polymer layer,
It is already known to use a laminate of a foam layer and a polymer solution layer (JP-A-60-123333, 60-183343 and 60-24).
2490 publication).

(Problems to be solved by the invention) However, when a label made of a plastic film is applied to the hollow molded container by an in-mold label operation,
Wrinkles and blisters on the label tend to significantly impair the appearance of the attached label, and the adhesion between the label and the outer surface of the container is insufficient, causing the label to peel off from the container when the container is stored or moved. There is also a tendency to fall or drop.

Therefore, the object of the present invention is to prevent the occurrence of wrinkles and blisters in the label in the plastic hollow molding container in which the label is attached to the outer surface by the label operation in the mold, and to ensure the adhesion and peeling resistance between the label and the outer surface of the container. To provide a labeled container having improved properties.

(Means for Solving the Problems) According to the present invention, in a labeled container comprising a hollow container formed by blow molding of plastic and a label provided by an in-mold label operation on the outer surface of the side wall of the container, A thin coating layer of a stretched olefin resin film substrate with a foaming ratio of 1.3 to 1.8 times and a draw ratio (longitudinal direction) of 1.1 to 1.5 times and a non-foaming olefin resin on the outer surface of a hollow container at least the outer surface of which is made of olefin resin. There is provided a hollow container with a label, characterized in that a label comprising a laminated body of (1) and (2) is attached to an in-mold label.

In this label, the expanded expanded olefin resin film substrate preferably has a thickness of 30 to 300 μm and the thin coating layer has a thickness of 3 to 50 μm, and the expanded expanded olefin resin film substrate 5 to 50 μm, particularly 8 to
Those having a cell wall thickness of 30 μm are preferred.

(Function) When manufacturing a hollow molded container, a plastic parison in a molten state or a softened state is expanded by blowing a pressurized fluid in the mold, and the expanded plastic comes into contact with the cavity surface of the mold and is cooled. By doing so, it is molded into the shape of a container, and finally the mold is opened and taken out to the outside in the shape of a container. In the in-mold label operation, prior to blow molding the parison, the label is held on the interior surface of the cavity and the expanded molten plastic parison contacts the label to promote thermal bonding.

According to the present invention, when a label is used, a laminate of a stretched expanded olefin resin film substrate having a foaming ratio of 1.3 to 1.8 times, particularly 1.4 to 1.7 times and a thin coating layer of a non-foamed olefin resin is used in the above-mentioned in-mold label operation. It is based on the finding that a labeled hollow container having no adhesiveness and peeling resistance between the container and the label can be obtained without the occurrence of fuzz and wrinkles on the outer surface of the label.

First, in the label used in the present invention, it is extremely important that the foamed olefin resin film substrate is stretched, that is, molecularly oriented. When a label based on an unstretched foamed film is attached to a hollow molded container by the in-mold label method, wrinkles, blisters and the like are generated on the outer surface of the label and the appearance characteristics are deteriorated. Adhesion and peel resistance are also lower than those adhered outside the mold. The reason for this is that the density of the plastic is smaller in the molten state than in the solid state at room temperature, so that the molding container contracts considerably in the solid state at room temperature as compared with the state in which it is attached to the label (molten state). It seems to be because.

The shrinkage rate at the time of this molding (hereinafter referred to as molding shrinkage rate) is particularly large in the olefin-based resin as compared with other resins, which is a particular problem.

On the other hand, in the present invention, by using a stretched olefin resin film as the base film of the label, it becomes possible to impart heat shrinkability to the label in proportion to the molding shrinkage of the container. It succeeded in keeping the outer surface of the label smooth and improving the adhesiveness with the container.

The label substrate used in the present invention has an expansion ratio of 1.3 to 1.8.
It is also particularly important that it consists of a doubled foam film, in particular 1.4 to 1.7 times. That is, the cell structure in the foamed film also plays an important role in allowing the shrinkage of the label commensurate with the molding shrinkage rate. When the expansion ratio is smaller than the above range, the auxiliary effect for allowing the shrinkage of the label becomes insufficient, and blisters and wrinkles are observed to some extent. Further, if the expansion ratio is larger than the above range, the cells are likely to expand when the label is manipulated, so that blisters and the like of the label become conspicuous.

According to the present invention, these effects are combined to achieve the above object. The thin coating layer of the non-foamed olefin resin provided on the stretched foamed olefin resin film not only maintains the smoothness of the label and gives a glossy effect to the label printing, but also has an auxiliary effect of preventing label blister. Have. Further, the stretched foamed olefin resin film may have the cell wall thickness described above,
If this thickness is smaller than the above range, blisters and wrinkles are likely to occur.

(Example) In FIG. 1 showing an example of a cross-sectional structure of a label used in the present invention, the label 1 is provided with a stretched foamed olefin resin film substrate 2, a printing ink layer 3 provided on the surface thereof, and a printing ink layer provided thereon. And a thin coating layer 4 of non-foamed olefin resin. Instead of applying the printing ink layer 3 on the stretched foamed olefin resin film, it may be provided on the non-foamed olefin resin coating layer 4. The stretched olefin resin film layer 2 generally shows sufficient thermal adhesive force to the outer surface of the container to be molded, but when sufficient thermal adhesive force is not obtained, the stretched olefin resin film layer 2 itself is provided below the film layer 2. A publicly known hot melt adhesive layer or anchor may be provided.

In FIG. 2 for explaining the in-mold label operation, in step A, prior to the blow molding of the plastic parison, the blow split molds 5a and 5b are in an open state, and the cavity surface 6 of at least one of them is Label 1 is applied in advance. That is, the cavity surface 6 has a portion for supporting the label 1, the reduced pressure suction mechanism 7 is provided in this portion, and the label 1 is held on the cavity surface 6 by suction. In this case, the label 1 has a positional relationship in which the stretched foam film substrate 2 is on the inside and the printing layer 3 is on the outside.
The application and fixing of the label 1 to the cavity surface 6 can be performed not only by suction but also by static electricity, for example.

Next, in step B, the molten plastic parison 9 is extruded from the die 8, the blow split molds 5a and 5b are closed, and pressurized gas is blown into the closed parison 9.

In step C, the parison that expands in the mold is pressed by the label 1 held on the mold surface to bring them into close contact and heat adhesion, and the expanded parison comes into contact with the mold surface and is cooled. The labeled container 10 is provided.

Blow molding is performed by any blow molding method such as injection blow, two-stage blow, sheet forming, stretch blow, etc. in addition to the direct blow method using a horizontal rotary blow molding machine or a vertical rotary blow molding machine. be able to.

In the present invention, as the plastic constituting the container, for example, crystalline polypropylene, crystalline propylene-
Polyolefins such as ethylene copolymers, crystalline polybutene-1, crystalline poly-4-methylpentene-1, low-, medium- or high-density polyethylene; aromatic vinyl polymers such as polystyrene and styrene-butadiene copolymers. A vinyl halide polymer such as polyvinyl chloride or vinylidene chloride resin; a nitrile polymer such as an acrylonitrile-styrene copolymer or an acrylonitrile-styrene-butadiene copolymer; nylon 6, nylon 6,6, para or metaxylylene Polyamides such as adipamide; polyesters such as polyethylene terephthalate and polytetramethylene terephthalate; various polycarbonates; thermoplastic resins such as polyacetals such as polyoxymethylene.

The hollow molding container may have a single-layer or multi-layer structure, for example, a container composed of a single layer of polyolefin or polyethylene terephthalate, or polyolefin and polyethylene terephthalate as inner and outer layers, and a gas barrier thermoplastic resin between them. An example of the container is a multi-layer container. Examples of the gas barrier resin include ethylene-vinyl alcohol copolymers having an ethylene content of 50 to 20 mol%; xylylene group-containing polyamides; gas barrier polyesters; high nitrile group-containing polymers; vinylidene chloride resins and the like. A gas barrier resin known per se can be used. When there is no adhesiveness between the inner and outer layers and the intermediate layer, an adhesive resin such as an acid-modified olefin resin, various copolyamides and various copolyesters may be contained between them.

On the other hand, as the olefin resin constituting the label, in addition to the polyolefins exemplified above, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), olefin resins such as ionomers Can be used. The foamed film of an olefin resin is obtained by blending a foaming agent such as azobisisobutyronitrile, azodicarbonamide, diazoaminobenzene or benzenesulfonylhydrazide with an olefin resin, and melt-extruding the film to form a film. The content of the foaming agent is preferably a low compounding amount of 0.05 to 2% by weight so that the expansion ratio can be obtained. Stretching of the foamed film can be carried out uniaxially or biaxially. In general, 1.
It is preferable to carry out stretching of 1 to 1.5 times, and in the case of biaxial stretching, it is desirable to carry out stretching of 1.05 to 3 times, particularly 1,1 to 1.5 times in the transverse direction.

Lamination of the stretched foam film and the unfoamed coating layer,
It is carried out by any means such as dry lamination, extrusion coating, and coextrusion.

In the present invention, it is preferable to apply the label so that the main molecular orientation direction of the expanded olefin resin is aligned with the longitudinal direction of the label (this is generally the height direction of the container).

INDUSTRIAL APPLICABILITY The present invention is particularly effective for performing an in-mold label operation on a hollow container whose outer surface is made of an olefin resin such as polypropylene. In this case, as the stretched foam film substrate of the label, polypropylene, polyethylene or the like is used. It is particularly suitable to use a stretched foam film.

(Effect of the Invention) According to the present invention, in the labeled hollow molding container by the in-mold label operation, by using the label based on the stretched olefin resin film, the heat shrinkage corresponding to the molding shrinkage of the container is applied to the label. Can be granted,
This makes it possible to prevent the occurrence of wrinkles and blisters on the label, improve the appearance characteristics of the label, and improve the adhesiveness and peeling resistance between the label and the outer surface of the container.

Moreover, by performing the in-mold label operation, it is possible to streamline the container manufacturing process by omitting the troublesome adhesive application operation and label sticking operation.

The invention will be illustrated by the following example.

Example 1 A uniaxially stretched polypropylene foam film having a melting point of 157 ° C, a foaming ratio of 1.5 times, an average thickness of foam cell walls of 15 μm, and a thickness of 100 μm is printed on one side, and the thickness is further applied on top of it. A 15 μm thick coating layer of ethylene propylene copolymer was provided by extrusion coating.

Next, an oval-shaped label having a length of 90 mm and a width of 60 mm was punched out from the obtained label base material and attached to a bottle surface made of an ethylene-propylene copolymer having a melting point of 157 ° C. by the process as shown in FIG.

The in-mold label bottle thus obtained had a very good appearance, the surface of the label had good gloss, and no wrinkles were observed.

Example 2 One side of the uniaxially stretched polypropylene foam film having a thickness of 100 μm used in Example 1 was printed, and a 20 μm thick film of ethylene propylene copolymer was further adhered thereon by a urethane adhesive.

Then, an in-mold label bottle was produced from the obtained label base material in the same manner as in Example 1. The appearance of the obtained bottle was very good, the gloss of the label surface was good, and no wrinkles were observed.

Comparative Example 1 A label base material having a melting point of 157 ° C., a foaming ratio of 1.5 times, an average thickness of a foam cell wall of 3 μm, and a thickness of 80 μm on one side of a uniaxially stretched polypropylene foam film. An in-mold label bottle was produced in the same manner as in Example 1. The label surface of the obtained bottle had a poor appearance with small wrinkles such as orange peel.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a cross-sectional structure of a label used in the present invention, and FIG. 2 is a diagram for explaining an in-mold label operation. Reference numeral 1 is a label, 2 is a stretched foamed olefin resin film substrate. 3 is a printing ink layer, 4 is a coating layer, 5
Is a blow split type, 6 is a cavity surface, 7 is a reduced pressure suction mechanism, 8 is a die, 9 is a parison, and 10 is a labeled container.

Claims (4)

[Scope of utility model registration request] 1. A labeled container comprising a hollow container formed by plastic blow molding and a label provided on the outer surface of the side wall of the container by an in-mold label operation, wherein at least the outer surface is made of an olefin resin. 1.3 to 1.8 times the expansion ratio and the draw ratio (longitudinal direction) on the outer surface of
A hollow container with a label, wherein a label comprising a laminate of a stretched expanded olefin resin film substrate of 1.1 to 1.5 times and a thin coating layer of a non-expanded olefin resin is attached to an in-mold label. 2. A stretched foamed olefin resin film substrate is 30
~ 300μm thickness and thin coating layer 3 ~ 50
The labeled hollow container according to claim 1, which has a thickness of μm. 3. The labeled hollow container according to claim 1, wherein the laminated body is obtained by laminating a stretched olefin resin film on the thin coating layer. 4. A stretched expanded olefin resin film substrate is 5
The labeled hollow container according to claim 1, which has a cell wall thickness of from 50 to 50 µm.