JPH08132477A - In-mold label container and production thereof - Google Patents

Abstract

PURPOSE: To laminate a label having barrier properties at an accurate position by molding an in-mold label on a container using a side surface label and a bottom surface label and forming a barrier layer composed of a metal foil layer or a thermoplastic resin layer to the respective labels while forming the layer laminated to a container main body by the injection molding of the same material of the container. CONSTITUTION: As an injection resin material becoming a container main body, polypropylene is used and, as a label material, a three-layered film wherein a polyethylene terephthalate film, aluminum foil and a polypropylene film are successively laminated is used. This label material is formed by printing characters or the like on the PET film being the outermost layer and subsequently laminating the aluminum foil being a barrier layer to the printed PET film by an adhesive and laminating the polypropylene film being the innermost layer to the aluminum foil by an adhesive. The label material is arranged to the side surface and bottom surface of a female mold 4 and, after the female mold 4 is pushed in, a resin is injected into a cavity through the gate hole 6 of the bottom surface label 2 to perform in-mold label injection molding.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an in-mold label container capable of obtaining a reliable gas barrier property and a method for producing the same.

[0002]

2. Description of the Related Art In in-mold label molding, a label having a heat-sealing layer is set in advance in a mold during blow or injection molding, and the heat-sealing layer of the label is applied to the surface of the molded product by the heat of the resin during molding. This is a molding method in which labeling is performed simultaneously with molding by fusing.

[0003] As an in-mold label container using a label having a gas barrier property, for example, Japanese Utility Model Laid-Open No. 5-958 is used.
No. 47 discloses a plastic injection-molded product having a bottom and a thin container body, which has a thin and strong container body and a label having a high rigidity and a high gas barrier property on the entire outer peripheral surface of the cylinder wall and the entire lower surface of the bottom wall. It is possible to provide a barrier container having a structure in which the container is firmly fixed as an insert material, and thereby the mechanical strength of the entire container is enhanced by the rigidity of the label. Here, as the label material, one in which a main body layer made of strong paper or synthetic paper and a barrier layer made of a synthetic resin material having a gas barrier property are laminated is used.

[0004]

However, the conventional gas barrier in-mold label container and its manufacturing method have the following problems. (1) Since the label material is made of an opaque material such as paper or synthetic paper, even if the material of the container is transparent, the in-mold label container becomes opaque and it is impossible to provide a transparent container. (2) Since a gate hole (bottom) for resin injection is required at the center of the barrier layer and it remains in the molded product, gas permeation from this part cannot be avoided. (3) Since the position of the vacuum suction part provided in the female mold for fixing the position of the side label inserted in the mold at the time of molding is near the upper end of the container and separated from the resin injection part (near the bottom part), The label may be displaced from a predetermined position due to the impact of resin injection. (4) When the side label inserted in the female die is pushed in by the male die, the lower edge of the label comes into contact with the female die due to variations in the punching dimensional accuracy of the label, causing waviness, overlapping, etc. of the label, and the injected resin is There is a possibility of getting around the gap between the label and the mold. (5) Label peeling may occur due to the difference in shrinkage due to the difference in material between the container (especially in the case of a rectangular container) and the label. (6) At the time of injection molding, at the point where the cavity in the mold rises at a substantially right angle from the bottom to the side surface, the resin injection pressure on the label becomes relatively high, so that the ink layer and heat seal layer of the label are subject to friction and the like. Flow may occur.

Therefore, it is an object of the present invention to solve the above-mentioned problems and to accurately arrange the label on the container, and to surely obtain the barrier property.

[0006]

In order to achieve the above object, the present invention is a thermoplastic resin injection molded container which is in-mold label-molded using a side label and a bottom label, wherein each label is at least A barrier layer composed of a metal foil layer or a thermoplastic resin layer, wherein the layer laminated on the container body side is composed of a material of the same quality as the container body or a material having adhesiveness to the container body. A mold label container is provided.

The in-mold label container of the present invention may have a structure in which the bottom label does not have a resin injection gate hole. If this hole is not provided, it becomes more difficult for oxygen and the like to permeate.

The in-mold label container of the present invention may have a structure in which the leg portion of the container body has reinforcing ribs. This allows the container (especially when it is a rectangular container)
The peeling of the label due to the difference in shrinkage due to the difference in the material of the label can be prevented.

Further, the present invention is a method for manufacturing an in-mold label container using a side label and a bottom label, wherein the side label is vacuum-sucked and fixed at a position where a bottom cavity surface is extended. The present invention provides a method of forming by molding. As a result, the position of the side label that first comes into contact with the resin is fixed when the resin is injected, so that it is possible to effectively suppress the phenomenon that the side label deviates from a predetermined position or is wavy due to the impact of the resin injection.

Further, the present invention is a method for manufacturing an in-mold label container using a side label and a bottom label, wherein the side label has a dimension such that the total height of the side cavity of the mold is LH. When the inner circumference is LR, the height L1 of the side label and the length L2 in the circumferential direction are respectively L1 =
A method of performing in-mold label molding is provided, where LH-x and L2 = LR-y (mm). Here, x and y are preferably each independently about 0.6 to 1.2 mm. If it is less than 0.6, there is a possibility that label waviness, overlap, etc. may occur when L1 and L2 become longer due to variations in label punching dimensional accuracy, or due to label elongation due to resin pressure during molding, and it exceeds 1.5. And, the gas barrier property is likely to be deteriorated.

Further, the present invention is a method of manufacturing an in-mold label container using a side label and a bottom label, using a mold having a curvature near the intersection of the bottom cavity and the side cavity. To provide a method for molding. By giving curvature to the molds (male and female) at the intersection, the resin injection pressure at this location is reduced and the label ink layer and heat seal layer may cause a "flow" due to the resin injection friction. Absent. However, this curvature increases the thickness of the container at the intersection, which easily causes "sink". Therefore, it is necessary to keep the thickness of the container at about 1.5 times or less that of the other parts. is there.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described.

The label material used in the present invention is generally
It is composed of a printing substrate layer, a gas barrier layer, and an adhesive layer with an injection resin. Each of these layers is independently formed into a film and bonded (dry laminated) via an adhesive, or
It can also be formed by melt extrusion (EC, coextrusion) of a part or all of the layers. Further, the printing substrate layer may be omitted depending on the use / purpose.

The film as the printing substrate is not particularly limited as long as it is generally printable, and for example, a polyester film, a polypropylene film, a nylon film or the like can be appropriately used.

Examples of the gas barrier layer include (a)
Aluminum foil (7 to 25 μm), (b) Laminated metal or metal oxide on a plastic film or the like by vapor deposition, for example, silicon oxide vapor deposited plastic film, aluminum oxide vapor deposited plastic film, aluminum vapor deposited plastic film, (c) Others, polyacrylonitrile resin,
EVOH (saponified ethylene vinyl acetate copolymer), P
A VDC (polyvinylidene chloride) film, a PVDC-coated biaxially stretched plastic film and the like can be mentioned, which can be appropriately selected according to the desired performance.

The adhesive layer is not particularly limited as long as it adheres to the injection resin, but usually, the same plastic material as the injection resin, polyethylene containing EVA (ethylene-vinyl acetate copolymer), etc. A resin having
Alternatively, a plastic film or the like in which those resins are co-extruded or coated can be preferably used.

The above layers are formed by a conventional method such as a dry lamination method, an extrusion lamination method, an extrusion coating method and other coating methods.

Injectable thermoplastic resin such as polypropylene, polyethylene, polystyrene and the like may be used for the in-mold label container body of the present invention.

[0019]

Embodiments of the present invention will be described below with reference to the accompanying drawings. <First Embodiment> In the first embodiment of the present invention, polypropylene is used as the material of the injection resin to be the container body, and polyethylene terephthalate film (12 μm) / aluminum foil (15 μm) / polypropylene film (60 μm) is used as the label material. The film which laminated | stacked three layers of these were laminated | stacked in order was used. This label material is the outermost layer, after printing characters, patterns, etc. on the PET film, laminated with the aluminum foil which is the barrier layer using an adhesive, and then the polypropylene film which is the innermost layer using the adhesive. Laminated 3-layer film is formed into a predetermined shape (side label is fan-shaped, bottom label is circular with gate hole in the center)
Punched out.

Next, as shown in FIG. 1, this label material (side label 1 and bottom label 2) is placed on the side and bottom of the female die 3, and the male die 4 is pushed in from above, and then the gate 5 (and The resin 7 was injected into the cavity through the gate hole of the bottom label 2 corresponding to the gate position, and ordinary in-mold label injection molding was performed.

As a result of measuring the barrier properties of the obtained molded container, the values of oxygen permeability and moisture permeability shown in Table 1 were obtained.

Since the innermost layer of this label material is the same material as the resin of the container body, the label material and the container body can be integrated without using an adhesive. Table 1 Barrier layer Oxygen permeability Water vapor permeability (cm ³ / pkg ・ day ・ atm) * (g / pkg ・ day) * Silicon oxide vapor deposition PET 0.07 0.0041 Polyvinylidene chloride 0.08 0.0043 Film Aluminum foil 0.06 0.00088 None 6.70 0.01 *) Measuring method: Oxygen permeability ... Temperature 23 ° C. , Humidity 90% RH, purge 3 days use MOCON OXTRAN vapor permeability ... calcium chloride gravimetric method, measurement 6 days, temperature 40 ° C., humidity 90% RH In addition, polypropylene is used as the material of the injection resin to be the container body. At the same time, in addition to the above, a film having the following layer structure was used in order from the outermost side to the innermost side as the label material.

Stretched polypropylene film (printing substrate) (25 μm) / aluminum foil (barrier layer) (15 μm
m) / stretched polypropylene film having a heat seal layer (adhesive layer) (25 μm), stretched polypropylene film (printing substrate) (25 μm
m) / silicon oxide vapor-deposited polyethylene terephthalate film (barrier layer) (12 μm) / stretched polypropylene film having a heat seal layer (adhesive layer) (25 μm)
m), unstretched polypropylene film (30 μm) / polyethylene terephthalate film (printing substrate) (12
μm) / Polyethylene terephthalate film deposited with silicon oxide (barrier layer) (12 μm) / Unstretched polypropylene film (adhesive layer) (30 μm), Stretched polypropylene film (25 μm) / Polyethylene terephthalate film (printing substrate) (12 μm)
m) / silicon oxide vapor-deposited polyethylene terephthalate film (barrier layer) (12 μm) / stretched polypropylene film having a heat seal layer (adhesive layer) (25 μm)
m), unstretched polypropylene film (30 μm) / polyethylene terephthalate film (printing substrate) (12
μm) / aluminum foil (barrier layer) (9 μm) / polyethylene terephthalate film (12 μm) / unstretched polypropylene film (adhesive layer) (30 μm).

Generally, when the label material is arranged on the side surface and the bottom surface of the female mold 3 after the label material is punched into a predetermined shape, the curl of the label material affects the yield of injection molding. That is, the smaller the curl of the label material, the better the yield.

In order to reduce the curling of the label material, it is preferable that the label material has a layer structure of a target type centering on the central layer.

In the label material having the above layer structure, a symmetrical layer structure can be formed with the center layer as the center, and the label material is a polyethylene terephthalate film or a silicon oxide vapor-deposited polyethylene terephthalate film. When considered as a terephthalate film, it has a symmetrical layer structure. Therefore, it is possible to reduce the curl of the label material during punching. Further, in the case of the label material having the layer constitution of ~, both the gas barrier property and the adhesiveness with the injection resin were good. <Second Embodiment> In the second embodiment of the present invention, as shown in FIG.
As shown in FIG. 5, in-mold label injection molding is performed by using a label material similar to that of the first embodiment and inserting a circular bottom label material having no gate hole 6 (see FIG. 1) in the center. It was In this embodiment, since there is no gate hole 6 in the bottom label material, when the resin 7 is injected, the cavity is filled with the resin while the bottom label 2 is pressed against the core (male) side. Therefore, in the molded product, the label having no gate hole 6 is laminated on the bottom surface in the container, and the barrier property is further enhanced (see Table 2). Further, in this embodiment, when a gate hole is provided in the bottom label (a hole punching step is required after the outer circumference punching of the label, accuracy of outer circumference punching and hole punching is required, and a high precision punching machine or the like is required. The label material is easier to process. Table 2 Barrier layer Oxygen permeability Water vapor permeability (cm ³ / pkg ・ day ・ atm) (g / pkg ・ day) Silicon oxide vapor deposition PET 0.05 0.0001 polyvinylidene chloride 0.05 0.0001 film aluminum foil 0.04 0.0001 <Third Example> In the third example of the present invention, as shown in FIG.
As shown in FIG. 3, the same label material as that of the first embodiment is used, and the female mold 3 in which the vacuum suction holes 8 (8 'position in the conventional apparatus) are provided at the position where the bottom cavity and the side cavity intersect with each other is shown. It was used for in-mold label injection molding. In this embodiment, since the side label 1 can be prevented from being exposed when the resin is injected, it is possible to prevent the side label 1 from being wrinkled or overlapped after molding. <Fourth Embodiment> In the fourth embodiment of the present invention, as shown in FIG.
As shown in (A) and (B), the same label material as in the first embodiment is used, and the total height of the side cavity of the mold (to be precise, the length along the side wall) is LH. When the inner circumference of the female die is LR (however, it gradually decreases from the top to the bottom), the height L1 of the side label and the circumferential length L2 are respectively L1 = LH -1, L2 = LR -1 (mm ), In-mold label injection molding was performed. In this embodiment, since the label size is set short, it is possible to prevent wrinkles, overlaps, and the like from occurring. In particular, since the lower end of the label does not come into contact with the bottom of the side cavity when the male die is pushed in after inserting the side label 1 into the female die, the label is laminated in close contact with the container body without waviness. As a result, as shown in FIG. 4 (C), the obtained molded container 10 is stacked on the side label 1 with a predetermined gap d, but the gas barrier property is hardly affected. <Fifth Embodiment> In the fifth embodiment of the present invention, as shown in FIG.
As shown in FIG. 6, the same label material as that of the first embodiment is used, and the reinforcing rib 1 is provided at a predetermined position of the leg portion of the container body 10.
1 was provided and in-mold label injection molding was performed. The reinforcing ribs 11 can prevent peeling of the label and the like due to the difference in contraction due to the difference in material between the container body 10 and the label.

Particularly, in the case of a rectangular container, it is preferable to provide ribs at the center points of the four sides of the leg. <Sixth Embodiment> In a sixth embodiment of the present invention, a polystyrene resin is used as an injection resin to be a container body, and a label material has a layer structure of polypropylene / adhesive / polyvinylidene chloride / adhesive / polypropylene. Using a coextrusion film (thickness 60 μm), printing was performed on the innermost layer side of the label, and then EVA resin (heat sealing agent) was coated thereon by the gravure coating method. Then, as shown in FIG. 6, a portion where the bottom cavity and the side cavity intersect (see numbers 12 and 1 in FIG.
Mold with curvature corresponding to 3) (female 3 and male 4)
Was used for in-mold label injection molding. Since the mold is given a curvature, the resin injection pressure on the label is lowered, and the ink layer and heat seal layer of the label can be prevented from "flowing" due to friction or the like. The above-mentioned portion has a relatively large wall thickness, and it is preferable to keep the wall thickness to 1.5 times or less in order to prevent "sinking" caused by the difference in wall thickness after cooling.

[0028]

As described in detail above, according to the in-mold label container of the present invention, the barrier property can be surely obtained. Moreover, according to the method for producing an in-mold label container of the present invention, a label having a barrier property can be laminated at an accurate position.

[Brief description of drawings]

FIG. 1 is an explanatory view illustrating a method for producing an in-mold label container of the present invention.

FIG. 2 is an explanatory diagram of a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of a third embodiment of the present invention.

4A to 4C are explanatory views of a fourth embodiment of the present invention.

FIG. 5 is an explanatory diagram of a fifth embodiment of the present invention.

FIG. 6 is an explanatory diagram of a sixth embodiment of the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location B29L 9:00 22:00 (72) Inventor Kanai Iman 1-chome, Ichigayagacho, Shinjuku-ku, Tokyo No. 1 Dai Nippon Printing Co., Ltd.

Claims (7)

[Claims] 1. A thermoplastic resin injection-molded container, which is in-mold label-molded using a side label and a bottom label, wherein each label has a barrier layer composed of at least a metal foil layer or a thermoplastic resin layer. The in-mold label container, wherein the layer laminated on the container body side is composed of a material having the same quality as the container body or a material having adhesiveness with the container body. 2. The container according to claim 1, wherein the bottom label does not have a resin injection gate hole. 3. The container according to claim 1, wherein the leg portion of the container body has a reinforcing rib. 4. A method for manufacturing an in-mold label container using a side label and a bottom label, wherein the side label is vacuum-sucked and fixed in a position where a bottom cavity surface is extended to perform molding. Method. 5. A method of manufacturing an in-mold label container using a side label and a bottom label, wherein the side label has a dimension such that the total height of the side cavity of the mold is LH and the inner circumference of the female mold is LR. Then, the height L1 of the side label,
The length L2 in the circumferential direction is L1 = LH-x, L2 =
A method of performing in-mold label molding as LR-y (mm). 6. x and y are each independently about 0.6 to.
The method according to claim 5, which is 1.2 mm. 7. A method of manufacturing an in-mold label container using a side label and a bottom label, wherein molding is performed using a mold having a curvature near the intersection of the bottom cavity and the side cavity. Method.