JPH0625870U - In-mold label - Google Patents

Abstract

(57) [Summary] [Purpose] An in-mold label to be joined to the surface of a plastic container that is blow-molded so that a convex pattern can be displayed on the label by using a mold with no engraved concave pattern on the inner surface. To do. [Structure] Base film 11, design printing ink layer 1
2, and a heat-sensitive foam ink layer 15 which has a heat-sensitive adhesive 13 as an inner layer and foams at a differential pressure molding temperature.
However, it has a layer structure in which a pattern corresponding to a desired convex pattern is provided on the layer interface inside the design printing ink layer 12. After the differential pressure molding is completed, a convex pattern appears on the surface of the label due to the foaming expansion pressure of the foamed ink layer 15 foamed in the differential pressure molding process.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an in-mold label for molding a plastic container having a convex pattern on the surface by a differential pressure molding method.

[0002]

[Prior art]

 Various plastic containers used as filling and packaging containers for beverages, seasonings, lotions, shampoos, etc. are manufactured by a differential pressure molding method represented by a blow molding method. The surface of the packaging container generally requires a label for displaying the product (contents), differentiating the product, and decoration, and the sticking of the label is typically performed by an automatic labeler. Although it is performed using an apparatus, in the molding operation of plastic containers by the blow molding method and the like, a method of simultaneously molding a container and attaching a label to its surface in one step is also in practical use. In this method, a label (in-mold label) is preliminarily attached to a desired position on the inner surface of a container molding mold (mold) and then the container is blow molded. This is called the in-mold label method. There is.

In FIG. 5, reference numeral 30 is a molding mold (vacuum suction / exhaust holes (not shown) are formed in the inner surface 31 of the mold), 40 is a label, and the label 40 is as shown in FIG. On the base film 11, a design printing ink layer 12 for displaying products and decorations, and a heat-fusible adhesive layer 13 for bonding with the surface of a container to be molded are laminated. The label 40 is attached to the inner surface 31 of the mold 30 (vacuum adsorption), and a plastic parison heated to a predetermined temperature is inserted and installed in the cavity of the mold 30 to perform blow molding, and the blow molding pressure P acts. By swelling and expanding the plastic 20 'and pressing it against the inner surface 31 of the mold, the molding of the container and the joining of the label 40 to the surface thereof are simultaneously achieved.

[0004]

[Problems to be solved by the invention] It is effective to enhance the label function as a visual and tactile effect by forming a convex pattern on the label attached to the surface of the plastic container in correspondence with the design printed pattern. Is. As a method of forming a convex pattern on the label 40 on the surface of the plastic container by the in-mold label method, as shown in FIG. 6, the inner surface 31 of the molding mold 30 has a concave pattern composed of concave portions 32 in which the desired convex pattern is reversed. Engraving the label, and attaching the label 40 so as to match the engraved pattern, blow molding the plastic 20 ', and press-fitting the plastic 20' and the label 40 pressed by this into the recess 32. Is used. However, engraving of the molding mold 30 is extremely expensive, and the mold cannot be used to mold plastic containers with different convex patterns on the labels, which reduces the versatility of the mold and greatly reduces the manufacturing cost of the container. Unavoidable rise. Not only that, it is not easy to attach the label 40 to the inner surface of the mold so as to exactly match the engraved pattern, and the considerable time required for its alignment reduces the efficiency of the container molding operation. This may cause the appearance of the label on the surface of the molded container that is displaced from the predetermined position, which in turn impairs the design effect of the label and may mean that a convex pattern is formed. Will be lost. INDUSTRIAL APPLICABILITY The present invention does not require engraving of the mold in the differential pressure molding of the plastic container by the in-mold label method, and can produce a convex pattern that exactly matches a predetermined position on the label surface. I will provide a.

[0005]

[Means for Solving the Problems]

 The present invention provides a substrate film 11, a design printing ink layer 12 formed on the outer surface or the inner surface thereof, and a surface of a plastic container for forming a differential pressure on a plastic container having a label having a convex pattern on the surface. In the in-mold label, which is a laminate having the heat-fusible adhesive layer 13 that is an inner layer in contact with the heat-sensitive foam ink layer 15 that foams at the differential pressure molding temperature, It is characterized in that the layer interface is provided with a pattern corresponding to a desired convex pattern.

[0006]

[Action]

In the differential pressure forming of the plastic container in which the label of the present invention is attached to the inner surface of the mold, the plastic that swells and expands toward the inner surface of the mold by the molding pressure is pressed against the label on the inner surface of the mold to retain its heat. As a result, the bonding by the heat-fusible adhesive layer 13 of the label occurs, and the foaming reaction of the heat-sensitive foaming ink layer 15 of the label occurs. The label on the surface of the plastic container in the mold immediately after the completion of differential pressure molding has a surface shape that does not have unevenness that matches the inner surface of the mold, but when the molding pressure is released and the container is removed from the mold, The swelling pressure of the foamed ink layer 15 causes outward swelling. Due to the foaming swelling stress of the foamed ink layer 15, as shown in FIG. 4, the label 10 on the surface of the molded container 20 has a bulging projection D _P (projection height of about 20) corresponding to the foaming ink application pattern. ˜200 μm) with a convex pattern. Since the mold that does not have the concave pattern engraving is used for the differential pressure molding, there is no need for strict alignment with the inner surface of the mold as in the case of using the concave pattern mold. Moreover, since the convex pattern of the label appears due to the foaming / expansion pressure stress of the foam ink layer printed on the label, the convex pattern does not cause misalignment.

Hereinafter, the present invention will be described with reference to the drawings illustrating an embodiment. The label 10 of the present invention shown in FIG. 1 has a substrate film 11 as an outer layer, and a heat-sensitive printing layer 12 for designing product markings and decorations, and a convex pattern on its inner surface. Foamable ink layer 15 and each layer of the heat-fusible adhesive layer 13 for the surface of the plastic container have a layer structure in which they are laminated and printed in this order. An overcoat 14 for imparting releasability to the inner surface 31 of the molding mold after the differential pressure molding is applied to the outer surface of the base film 11 if necessary.

2 and 3 show another example of the layer structure of the label of the present invention. In the label of FIG. 2, the design printing ink layer 12 is provided on the outer surface of the base film 11, and the releasable overcoat 14 is applied on the upper surface thereof, and the heat-sensitive foam ink layer 15 is formed on the inner side of the base film 11. The label of FIG. 3 has a thermosensitive foam ink layer 15 formed on the outer surface of the base film 11, and a design printing ink layer 12 and an overcoat 14 are laminated on the upper surface thereof. Have a configuration.

The heat-sensitive foamed ink in the label of the present invention includes various known heat-sensitive foamed inks represented by microcapsule type heat-sensitive foamed ink in which a low boiling point liquefied gas such as butane is enclosed in a thermoplastic resin capsule and kneaded in an ink vehicle. Among the foaming inks, those which cause a foaming reaction at the differential pressure molding temperature of the plastic container may be appropriately selected and used. The swelling increase ratio by the foaming reaction is, for example, 5 to 10 times. The heat-sensitive foam ink layer 15 is laminated and formed at a predetermined position in the label surface (for example, in conformity with the pattern drawn by the design printing ink layer 12) with a convex pattern to be exposed. The layer thickness of the foamed ink layer 15 varies depending on the foaming ratio and the like, but the layer thickness after the foaming reaction is, for example, 50 to 200 μm.

The material of the base film 11 of the label of the present invention is appropriately selected from various plastic films, such as polyester, polypropylene, polyethylene and polyvinyl chloride films, as in the case of ordinary in-mold labels. Can be used. In the case of a label having a layer structure in which the heat-sensitive foam ink layer 15 is provided on the inner surface side of the base film 11 as shown in FIGS. 1 and 2, the base film 11 has good stretchability as a plastic film. It is preferable to use a non-stretched or low-stretched film because the label surface is likely to swell due to the swelling stress of the foamed ink layer 15 foamed in the differential pressure molding step. Further, as the plastic film, one having a relatively small amount of heat shrinkage generated in the temperature lowering process of the container after the differential pressure molding is used, and the base film 11 has a difference in shrinkage amount between the base film 11 and the container. It is also advantageous to have a suitable amount of swelling in that the swelling of the label surface due to the foaming swelling stress of the foamed ink layer 15 is promoted. As a preferred example of the combination of the material type of the base film 11 which is advantageous for forming a convex pattern due to the foaming swelling stress of the foamed ink layer 15 and the material type of the plastic container, the container is a polyethylene resin. A combination in which the base material film 11 is a polypropylene resin film can be mentioned.

Unlike the labels shown in FIGS. 1 and 2, it has a layer structure in which a foaming ink layer 15 is provided on the outer surface of a base film 11 and a design printing ink layer 12 is formed on the upper surface thereof, as shown in FIG. In the case of a label, in selecting the material type of the base film 11, there is no restriction on the action of foaming swelling stress of the foamed ink layer 15 as described above, and various plastic films, paper, synthetic paper, metal A foil or the like can also be used.

The ink of the design printing ink layer 12 in the label of the present invention is a general ink used for label printing, and is shown as one layer in the figure, but it may be different depending on the design pattern to be exposed. Needless to say, the heat-fusible adhesive layer 13 is formed as a multicolor printing layer, and the hot-melt adhesive layer 13 is various hot-melt type adhesives (for example, ethylene-vinyl acetate) that exhibit an adhesive action at the differential pressure molding temperature of a plastic container. (Copolymers, chlorinated polypropylene, ethylene-acrylic acid ester copolymers, low density polyethylene, etc.) are selected and used as appropriate depending on the material type of the container. It doesn't differ. As the overcoat 14 for imparting releasability from the mold for molding to the surface of the label, those which are used in ordinary in-mold labels may be appropriately used.

The label of the present invention is manufactured by laminating each layer on the base film 11 by screen printing, gravure printing or the like according to a conventional method for manufacturing a label. The layer thickness of each layer may be appropriately set depending on the type of constituent material. For example, the base film 11 is about 50 to 100 μm, the design printing ink layer 12 is about 2 to 10 μm, and the heat-sensitive foam ink layer 15 is about. 10 to 30 .mu.m, the heat-fusible adhesive layer 13 is about 3 to 20 .mu.m, and the overcoat 14 provided as desired is about 2 to 5 .mu.m.

The differential pressure molding operation of the plastic container using the label of the present invention may be carried out according to a conventional method, and it does not require special conditions or restrictions. In order to allow the surface to swell sufficiently, the differential pressure molding pressure is released and the mold is removed from the mold while maintaining a relatively high temperature condition within the range where the handleability of the molded container is not impaired. It is better to remove the mold. In the above description, the blow molding method was mentioned as an example of the differential pressure molding, but the label of the present invention is used as an in-mold label in the vacuum molding method and various other differential pressure molding methods.

[0015]

[Effect of device]

 By using the label of the present invention for differential pressure molding of a plastic container, a plastic container with a label having a convex pattern can be molded by using a mold having no engraving process of a concave pattern. Therefore, the engraving cost of the mold becomes unnecessary and the versatility of the mold is improved, so that the differential pressure molding cost of the plastic container is reduced. In addition, the precise positioning of the label with respect to the engraved pattern and the time loss required for it, as in the case of using a mold having an engraved pattern, are eliminated, and the differential pressure molding operation efficiency is improved. Moreover, unlike the case where a mold having an engraved pattern is used, the convex pattern on the label surface does not shift in position, and the convex pattern which exactly corresponds to the predetermined position corresponds to the design printing of the label. Can be issued.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing an example of a laminated structure of a label of the present invention.

FIG. 2 is a sectional view schematically showing an example of a laminated structure of a label of the present invention.

FIG. 3 is a cross-sectional view schematically showing an example of the laminated structure of the label of the present invention.

FIG. 4 is a cross-sectional view schematically showing a convex pattern of a label on the surface of a plastic container molded by differential pressure molding.

FIG. 5 is an explanatory cross-sectional view of a main part showing differential pressure molding of a plastic container using a mold having no concave pattern on the inner surface.

FIG. 6 is an explanatory cross-sectional view of relevant parts showing differential pressure molding of a plastic container using a mold having an engraved concave pattern on its inner surface.

FIG. 7 is a cross-sectional view schematically showing a laminated structure of a conventional label.

[Explanation of symbols]

10: Label, 11: Substrate film, 12: Design printing ink layer, 13: Adhesive layer, 14: Overcoat, 1
5: Thermosensitive foam ink layer, D _P : Swelling protrusion. 20 ': Plastic container, 20: Plastic container. 30: differential pressure molding, 31: inner surface of mold, 32: concave.

Claims (1)

[Scope of utility model registration request] 1. A substrate film 11, a design printing ink layer 12 formed on an outer surface or an inner surface thereof, and a surface of a plastic container for performing differential pressure molding of a plastic container having a label having a convex pattern on its surface. In the in-mold label, which is a laminate having the heat-fusible adhesive layer 13, the heat-sensitive foam ink layer 15 that foams at the differential pressure molding temperature has a desired convex pattern on the layer interface inside the design printing ink layer 12. An in-mold label characterized by being provided with a pattern corresponding to.