JPH06328547A - Molding method for label-stuck hollow container - Google Patents

Abstract

PURPOSE:To stick a label easily to a container of thermoplastic resin non- compatible with a label base and prevent the generation of blisters by using the perforated label with its printed face being in contact with the mold wall face side, clamping a mold, introducing compressed air into a parison, expanding the parison and forming the container. CONSTITUTION:A label, on which perforations of diameters of 100-500mumphi are perforated at the ratio of 10-100psc./cm<2> per unit area from the printed face side of a base selected out of a pulp paper, an aluminum oil and a thermoplastic resin film is fixed in a mold 6 in a manner its printed face 3a is brought into contact with the wall face side of the mold 6. Then, a molten parison 5 of thermoplastic resin not compatible with the base is introduced into the mold 6. Then the mold 6 is clamped, and compressed air 7a is introduced from an air blowing nozzle 7 into the parison 5 to expand the parison 5 and mold a hollow container in the mold 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the formation of a label-bonded hollow container having good adhesion between the label and the molded hollow container even if the in-mold label does not have a heat seal resin layer. Regarding the method, the container decorated with this label is useful as a container for shampoo, rinse, motor oil, fruit juice drink and the like.

[0002]

2. Description of the Related Art Conventionally, a label is previously inserted in a mold and then a container is formed by blow molding to form a painted hollow container (JP-A-58-6901).
(See Japanese Patent Publication No. 5 and European Patent Publication No. 254923).

Such an in-mold label for a resin-molded container with a label is generally made of natural paper, synthetic paper, aluminum foil, plastic film or the like. Layered labels have been used.

In these labels, in order to provide a heat-sealable resin layer on the substrate layer to be printed, the label manufacturer usually applies the laminate or coating of the heat-sealable resin layer to the secondary layer. Since there is a request to the processing manufacturer, the number of production steps increases, and as a result, the cost of the label increases, which is a drawback. In addition, since the melting point and composition of the heat-seal resin provided on the label are limited depending on the material resin forming the hollow container, a heat-seal resin suitable for the container resin is selected as the adhesive layer. It was necessary to do. In addition, in general
Since the resin having a melting point in the range of 80 ° C to 140 ° C is used as the curable resin, when the labels for in-mold are stored in piles, the labels may block each other, or when the labels are printed. In addition, the slipperiness was poor, and there were drawbacks such as causing troubles such as sticking to the roll during feeding and discharging.

[0005]

SUMMARY OF THE INVENTION The present invention is a seat sheet.
Even for in-mold labels that do not have a resin layer,
It is intended to provide a method for molding a label-bonded hollow container in which the adhesive force between the label and the molded hollow container is practically sufficient by hollow molding.

[0006]

According to the present invention, perforations having a pore size of 100 to 500 μmφ per unit area are formed from the printing surface side of a substrate selected from pulp paper, aluminum foil, and thermoplastic resin film to 10 to 100 per unit area / cm ^2. The label perforated with the ratio is fixed in the mold so that the printing surface is in contact with the wall surface of the mold, and then a molten parison made of a thermoplastic resin that is incompatible with the base material is introduced into the mold. Provided is a method for molding a label-bonded hollow container, which comprises performing a hollow molding process including a process, a process of tightening a mold, and a process of introducing compressed air into the parison to expand the parison to form a container.

[0007]

In the wall surface of the perforated label of the in-mold label due to the perforation from the printing surface side, the printing surface side of the label is smooth and the surface on the laminating surface side opposite to the printing surface is the hole wall. Since the periphery is raised to form a convex portion, the perforated wall of the convex portion serves as an anchor to the wall of the hollow-molded hollow container, and the adhesive strength between the bite label and the hollow container is strengthened.
Further, since perforation of the label facilitates escape of air between the label and the hollow container at the time of hollow molding, blisters do not occur in the label-bonded hollow container.

(Detailed Description of the Invention) Label Base Material The label base material is pulp paper, aluminum foil, synthetic paper, polyethylene terephthalate, polypropylene,
Thermoplastic resin films such as polyamide, and laminates thereof can be used.

The thickness of the base material layer is generally 12 to 300 μm, preferably 60 to 200 μm. On the surface side of the base material layer, floral patterns, animal patterns, trade names, manufacturing makers, etc. Is printed, and from the print side of this label, a hot needle, an electronic
The hole diameter is 100 to 500 by means such as a rubber or a laser beam.
10 μmφ, preferably 200 to 400 μmφ perforations
~ 100 pieces / cm ² , preferably 20-80 pieces / cm ²
Are perforated.

As a result of this perforation, as shown in FIG. 1, the perforated (2) wall surface (2a) of the printing surface (3a) of the label (1) is smooth, but it is on the side of the bonding surface opposite to the printing surface. Hole wall surface (2
A convex portion is formed in b), and the protrusion wall (2b) bites into the hollow container (4) as an anchor, and the adhesive strength between the label (1) and the hollow container (4) is strengthened.

The height of the protrusion is usually 10 when the hole diameter of the perforation is 10.
In case of 0 μm, it is 30 μm, and the hole diameter of perforation is 500 μm
m is 150 μm, and the height of the convex portion is 30 to 15
It is in the range of 0 μm. Therefore, the hole diameter is 100 μm
If it is less than the above, the effect of anchoring in the wall of the hollow container is small, and practical adhesive strength cannot be obtained. When the hole diameter of the perforations is 500 μm or more, the anchoring effect into the hollow container wall is large and sufficient adhesive strength can be obtained. However, when the label is inserted into the mold by the vacuum suction method, the label is attached to the inner wall surface of the mold. When it is attached, the degree of vacuum does not reach a certain level, and labels often slip off.

Hollow container material The thermoplastic resin used to form the hollow container is polypropylene, polyethylene, polyvinyl chloride,
When polyethylene terephthalate, polyamide or the like is used and a resin that is incompatible with the label substrate is used, the effect that the heat seal resin layer of the present invention is unnecessary can be fully enjoyed.

For example, when the label substrate is pulp paper or aluminum foil, all of the above-mentioned thermoplastic resins can be used as the molding material for the hollow container, and when the label substrate is non-polar polypropylene or polyethylene, Thermoplastic resins such as polar polymers such as polyethylene terephthalate, polycarbonate, polyamide and polyvinyl chloride can be used as the hollow container material.

In- mold Hollow Molding In the method for manufacturing a label- bonded hollow container of the present invention, as shown in FIG. 2, the perforated in-mold label (1) is used as a cavity () for a mold (6). The printing side (3a) is disposed inside the mold (6a) so as to contact the inner surface (6a) of the cavity of the mold (3), and the in-mold label (1) is sucked onto the inner wall (6b) of the mold (6). ) Is fixed, a molten parison (5) of a thermoplastic resin as a container molding material is introduced into a mold (6), and then the mold (6) is closed and compressed air (7a) is blown from a blowing nozzle (7). ) The parison (5)
Introduced into the mold, the parison (5) is expanded and shaped along the mold inner wall (5b), and the mold inner wall (6)
The in-mold label (1) fixed to b) is pressed from the inside to press the in-mold label (1) against the container wall to form a label-bonded hollow container.

[0015]

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The evaluations in Examples and Comparative Examples were performed according to the following criteria. It was classified into the following 5 stages according to the blister label attachment status. 5: Adhesion on the entire surface 4: Less than 100% to 90% of the label is adhered 3: Less than 90% to 70% of the label is adhered 2: Less than 70% to 50% of the label is adhered 1: Label adhesion strength of less than 50% of the label adhered The adhesive strength (T-shaped peeling) of the 15 mm width of the adhered label was measured.

(Example 1) (1) Production of label for in-mold Melt flow rate (MF) as a resin for forming a base material layer
R) 0.8 g / 10 minutes, 70% by weight of homopolypropylene having a melting point of 164 ° C., high-density polyethylene 1 having a melting point of 134 ° C.
2% by weight and 18% by weight of ground calcium carbonate having an average particle size of 1.5 μm were blended (A), kneaded by an extruder set at 270 ° C., extruded into a sheet, and cooled by a cooling device. To obtain an unstretched sheet.

Next, this sheet was heated to 145 ° C. and then stretched 5 times in the longitudinal direction to obtain a stretched sheet (A layer) 5 times in the longitudinal direction.

On the other hand, a mixture (B) of 58% by weight of homopolypropylene having an MFR of 4.0 g / 10 min and 42% by weight of calcium carbonate having an average particle size of 1.5 μm was kneaded by an extruder set at 270 ° C. After that, the sheet was supplied to a die and laminated on both sides of the sheet (A layer) stretched 5 times in the longitudinal direction to obtain a laminated sheet (B / A / B) of 3 layers.

Next, this laminated sheet was reheated to about 155 ° C., then stretched in the transverse direction by 7 times, subjected to corona discharge treatment on both sides, cooled to 55 ° C., and then ear portions. And the thickness of each layer (B / A / B) is 20 /
A 50/20 μm three-layer synthetic paper was obtained.

After offset printing was performed on one side of the B layer of this synthetic paper, perforations having a pore diameter of 200 μm were formed at a rate of 25 per 1 cm ² from the printed side by using a hot needle. Next, hollow molding in-mold label (70 mm
× 90 mm).

The label was fixed to the die with a label inserter by a vacuum suction method so that the printed surface of the punched label was in contact with the wall surface of the die. Then, after melt-extruding the polyvinyl chloride parison at 190 ° C.,
It is introduced into the split mold, the split mold is clamped, and 4.2 kg / cm ² of compressed air is supplied into the parison to expand the parison and form it into a container, and the in-mold label is attached to the container wall. I made it stick. Next, after cooling the mold, the mold was opened and the hollow container was taken out.

Evaluation In this hollow container, neither label shrinkage nor blister generation was observed. Further, 100 labels were continuously supplied to the split mold for hollow molding with the label inserter, but there was no supply error (such as the label dropping from the mold) once. The adhesive strength between the label and the hollow container was measured, and the results are shown in Table 1.

Examples 2 to 6 Comparative Examples 1 to 4 The label base material and thickness, the hole diameter and the number of holes per unit area, the perforation processing direction, and the resin type of the hollow container were changed as shown in Table 1. A label-bonded hollow container was produced in the same manner as in Example 1 except that the above was performed. The results are shown in Table 1.

[0024]

[Table 1]

[0025]

The label of the present invention formed as described above is
By punching from the printing surface side, the periphery of the hole wall on the obtained bonding surface side is raised to form a convex portion,
As a result, it can be easily attached to a container made of a thermoplastic resin that is incompatible with the label base material. Moreover, since the air present between the label and the container resin wall can be easily released to the outside of the label sticking portion by providing the perforation, the conventional label (the label that is not perforated) It can be used as an in-mold molding label for round bottles and irregular-shaped bottles that could not be molded due to blister generation.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a label-adhered container obtained by in-mold molding using the label of the present invention.

FIG. 2 is a cross-sectional view of a molding machine used in a method for manufacturing a label-bonded hollow molding container used in an example of the present invention.

[Explanation of symbols]

 1 label 2 hole 2a hole wall on the printing surface side 2b hole hole on the bonding surface side 3a printing surface side of the label 3b bonding surface side of the label 4 hollow container 5 parison 6 mold 6a mold cavity 6b mold inner surface 7 Air blowing nozzle 7a Compressed air

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Claims (2)

[Claims] 1. A pore size of 10 from the printing surface side of a substrate selected from pulp paper, aluminum foil and thermoplastic resin film.
Perforation of 0-500 μmφ 10-100 per unit area
Labels perforated at a rate of pcs / cm ² are fixed in a mold so that the printed surface is in contact with the wall surface of the mold, and then melted in a mold made of a thermoplastic resin that is incompatible with the base material. Hollow molding characterized by performing hollow molding, which comprises a step of guiding the parison, then a step of tightening the mold, and a step of introducing compressed air into the parison to expand the parison and form a container in the mold. Molding method for containers. 2. A label on a perforated wall surface of a label, wherein the printing surface side of the label is smooth and the surface of the laminating surface side is raised around the hole wall to form a convex portion. Item 1. A method for forming a label-bonded hollow container according to Item 1.