JP2008225293A - In-mold label - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an in-mold label excellent in processability by suppressing curling through devising laminated composition of a label substrate having not a single layer of a film or paper but multi-layer composition with decorative films especially for providing decorativeness. <P>SOLUTION: The in-mold label comprises a laminated material wherein at least a surface substrate layer 1, a shape retaining layer 2, and a label substrate layer 3 are successively laminated. The surface substrate layer is a hologram processed film (a decorative film) wherein an oriented film 1a, a hologram emboss formed resin layer 1b, and a light reflection layer 1c are successively laminated. The shape retaining layer comprises aluminum foil, and the label substrate layer comprises any of paper, synthetic paper, and plastic film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an in-mold label, and particularly to an in-mold label in which curl suppression is imparted to a label having a multilayer structure with a decorative film, not a film or a paper single layer, for the purpose of imparting aesthetic appearance.

  Conventionally, as a cup container used for a dessert food, a cup container by plastic injection molding is often used. As a technique for applying a pattern expression to the surface of such a cup container, a technique of printing directly on the side of the container after molding the cup container with a silk printing machine or a technique of attaching a print label with a labeler has been often used. However, with the former, gradation expression is very difficult due to the number of colors of silk printing and restrictions on expression. In the latter case, since a planar label is attached to the three-dimensional object, a sense of unity with the container cannot be obtained. In addition, there is a problem that peeling due to condensation may occur during distribution.

  In response to these problems, an in-mold label molding method in which a resin is introduced after a label is inserted into a mold and a container integral with the label is molded has been widely used. In this in-mold container, since the printed substrate is processed with labels, there are no restrictions on expression, and the label and container are integrated and molded. Can be granted.

  By the way, in in-mold label molding, a label to be bonded to the inner surface of the mold cavity is fixed by means such as vacuum suction, and then a molten resin is injected into the mold to mold a container integrated with the label. Is. When the label is inserted, the labels adhere to each other due to the charging of the label, surface smoothness, and adhesiveness of the heat seal layer, and as a result of being inserted in a state where a plurality of labels overlap in the mold, the label in the mold remains (clogged) ) Can cause troubles such as machine stoppage and leakage due to the outflow of overlaid products. In particular, it is indispensable to prevent adhesion of labels and to impart appropriateness for squeezing in in-mold label molding.

  As a technique for avoiding such a problem, for example, a releasable coat layer or resin layer is provided as an adhesion prevention layer on the surface of a base film coated with a hot melt layer as a heat seal layer with an in-mold molding container. A technique has been developed (see, for example, Patent Document 1).

  In addition, the label base material is multilayered, such as by laminating a vapor deposition film or hologram on the label base material to give eye catching properties, or by laminating a barrier film layer made of an inorganic oxide vapor deposition film. By doing so, it is possible to give various functions to the molded container, but due to the multilayering, it tends to be extremely difficult to finish the label product flat without curling.

In recent years, the label structure has evolved from a single-layer product to a multi-layer product in order to differentiate it from other products and demand more eye catch. In in-mold molding, it is essential to reduce label curl because misalignment during in-mold molding leads to fatality of the molded product. In the case of a single layer constitution label, curl is hardly a problem, but in the case of a laminate constitution label, curling occurs due to the hygroscopicity of the bonded base material, the difference in stretchability due to heat and tension, and winding. In particular, for a hologram processing film (decorative film) in which the front substrate itself has a multilayer structure, since it includes a thermoplastic resin layer, even a single body is curled by the influence of heat. When the label base material layer is paper, curling occurs due to moisture absorption / drying. In order to suppress these temperature and humidity-dependent curling, it is very difficult to manage the temperature during label distribution and the distribution management such as packing with a barrier packaging material.

Prior art documents are shown below.
JP-A-2-139328

  The present invention is intended to solve such problems of the prior art, and in particular for the purpose of imparting aesthetics, a label base material having a multilayer structure with a decorative film rather than a film or paper single layer. An object of the present invention is to provide an in-mold label excellent in processability by curling by laminating the layers.

  The present invention has been made to solve the above problems, and the invention according to claim 1 of the present invention includes at least a surface base material layer (1), a shape retaining layer (2), and a label base material. An in-mold label made of a laminated material in which layers (3) are sequentially laminated, wherein the surface base material layer (1) comprises a stretched film (1a), a hologram embossing resin layer (1b), and a light reflecting layer (1c). It is a hologram processing film (decorative film) formed by laminating sequentially, the shape retaining layer (2) is made of aluminum foil, and the label base material layer (3) is any one of paper, synthetic paper, and plastic film. This is an in-mold label.

  The invention according to claim 2 of the present invention is the in-mold label according to claim 1, wherein the aluminum foil has a thickness in the range of 9 to 30 μm.

  The invention according to claim 3 of the present invention is the in-mold label according to claim 1 or 2, wherein a heat sealant coat layer (4) is formed on the back surface of the label base material layer (3). It is an in-mold label characterized.

  The invention according to claim 4 of the present invention is the in-mold label according to any one of claims 1 to 3, wherein printing ink is applied to the front or back surface of the stretched film (1a) of the front substrate layer (1). The in-mold label is characterized in that a layer (5) is formed.

  The invention according to claim 5 of the present invention is the in-mold label according to any one of claims 1 to 4, wherein the stretched film (1a) is a polyethylene terephthalate film. .

  The invention according to claim 6 of the present invention is the in-mold label according to any one of claims 1 to 5, wherein the hologram embossing resin layer (1b) is a thermoplastic resin. It is a label.

  The invention according to claim 7 of the present invention is the in-mold label according to any one of claims 1 to 6, wherein the light reflection layer (1c) is a metal vapor deposition layer or a plurality of inorganic oxides having different refractive indexes. It is an in-mold label characterized by being a vapor deposition layer.

  The invention according to claim 8 of the present invention is the in-mold label according to any one of claims 1 to 7, wherein the paper is coated paper coated with polyvinyl (PVA). It is a mold label.

  The invention according to claim 9 of the present invention is the in-mold label according to any one of claims 1 to 8, wherein the synthetic paper is a polypropylene resin coextruded film containing titanium oxide in a core layer. It is an in-mold label.

  The invention according to claim 10 of the present invention is the in-mold label according to any one of claims 1 to 9, wherein the plastic film is a biaxially stretched polystyrene film (OPS) or a biaxially stretched polyethylene terephthalate film (OPET). It is an in-mold label characterized by the above.

  The in-mold label according to the present invention is an in-mold label made of a laminated material in which at least a surface base material layer, a shape retention layer, and a label base material layer are sequentially laminated, and the surface base material layer is a stretched film, hologram embossing A hologram processing film (decorative film) formed by sequentially laminating a forming resin layer and a light reflecting layer, the shape retaining layer is made of aluminum foil, and the label base material layer is one of paper, synthetic paper, and plastic film As a result, temperature- and humidity-dependent curling can be suppressed, temperature management during label distribution, distribution management such as packing with a barrier packaging material, and the like, and in-mold molding suitability are excellent.

  The embodiment of the in-mold label according to the present invention will be described in detail with reference to FIG. 1, but is not limited thereto.

  FIG. 1 is a side sectional view showing an embodiment of the layer structure of an in-mold label according to the present invention.

  As shown in FIG. 1, the in-mold label of one embodiment of the present invention is made of a laminated material in which at least a front substrate layer (1), a shape retaining layer (2), and a label substrate layer (3) are sequentially laminated. A hologram processing film (decoration) in which the surface base layer (1) is formed by sequentially laminating a stretched film (1a), a hologram embossing resin layer (1b), and a light reflection layer (1c). The shape retaining layer (2) is made of an aluminum foil, and the label base material layer (3) is any one of paper, synthetic paper, and plastic film.

  The thickness of the aluminum foil is preferably in the range of 9 to 30 μm. If the thickness is less than 9 μm, sufficient shape retention cannot be obtained, curling occurs when the label is pulled up, and The label cannot be inserted into the mold for molding, and molding is impossible. On the other hand, when the thickness exceeds 30 μm, curling can be prevented, but the rigidity becomes too strong, and in particular, the suitability for in-mold molding of a cylindrical hollow bottle or the like is hindered.

  As described above, the surface base layer (1) is a hologram processed film (decorative film) formed by sequentially laminating a stretched film (1a), a hologram embossing resin layer (1b), and a light reflecting layer (1c). It is formed with.

  A printing ink layer (5) can be formed on the front or back surface of the stretched film (1a) of the front substrate layer (1). In particular, when it is provided on the surface of the stretched film (1a), a protective layer (not shown) can be provided as necessary to further protect the printing ink surface.

The printing ink for forming the printing ink layer (5) includes a color material composed of a pigment or a dye that gives color to the ink, a resin that adheres to the printed material while dispersing and holding the color material in fine particles, A vehicle composed of a solvent that stably dissolves the resin, retains the dispersibility of the color material, maintains the fluidity of the ink, and transfers the appropriate amount of ink from the printing plate, and further disperses the color material and develops color. For the purpose of improving the property, preventing precipitation, and improving the fluidity, it is formed from an auxiliary agent such as a surfactant. In particular, the colorant is preferably a pigment having good heat resistance and weather resistance.

  As a printing method, a gravure printing method, a flexographic printing method, a silk screen printing method, or the like can be used, but a gravure printing method is preferable for performing beautiful printing.

  As the stretched film (1a), transparency, rigidity (mechanical strength such as tensile strength and bursting strength), surface smoothness, workability (such as insert moldability), merchantability (such as printability), There are no particular restrictions on the type as long as economic efficiency (price, etc.) and safety and hygiene (non-toxicity, easy disposal, etc.) are satisfied.

  For example, a polyethylene terephthalate film (PET), a polypropylene film (PP), a polyamide film (Ny), etc. can be mentioned. Of the polypropylene film (PP), the biaxially stretched polypropylene film (OPP) is shrunk by heat. Large, unstretched polypropylene film (CPP) has poor transparency, and polyamide film (Ny) has poor transparency, so a polyethylene terephthalate film (PET) excellent in transparency, heat resistance, rigidity, etc. is used. It is preferable.

  The thickness of the film (1a) only needs to be a thickness that can be kept to the minimum necessary for transparency, rigidity, etc., and if it is too thick, the cost increases and the transparency is also unfavorably affected. If it is too thin, the strength, rigidity and the like are lowered, which is not preferable.

  Next, the hologram embossing resin layer (1b) is made of thermoplastic resin such as polyvinyl chloride resin, polycarbonate resin, polystyrene resin, polypropylene resin, unsaturated polyester resin, melamine resin, epoxy resin, urethane (meth) acrylate, Thermosetting resins such as epoxy (meth) acrylate, polyol (meth) acrylate, melamine (meth) acrylate, and triazine (meth) acrylate, or mixtures thereof, and thermoformable materials having radically polymerizable unsaturated groups Any one may be used as long as it has stability capable of forming a hologram image, but a thermoplastic resin is preferable from the viewpoint of molding processability, molding retention, cost, etc. Among thermoplastic resins, polypropylene resin is preferable.

  Further, the hologram image is not particularly limited, but for example, an embossed type that expresses an image by minute unevenness is preferable.

  Further, the stretched film (1a) and the hologram embossing resin layer (1b) can be combined into one layer, and this may be possible by selecting the material.

  Next, the light reflecting layer (1c) provided on the concavo-convex surface which is the hologram image forming surface of the hologram embossing resin layer (1b) is formed from a metal vapor deposition layer or a plurality of inorganic oxide vapor deposition layers having different refractive indexes. Is formed.

  For example, examples of the metal of the metal vapor deposition layer include aluminum, zinc, tin, and the like, but aluminum is preferable from the viewpoint of workability, mechanical strength, decorativeness, and the like.

Next, the inorganic oxide vapor deposition layer is obtained by alternately laminating a plurality of inorganic oxide vapor deposition layers having different refractive indexes with a specific film thickness. For example, magnesium oxide (refractive index n = 1.6), silicon dioxide (refractive index n = 1.5), magnesium fluoride (refractive index n = 1.4)
Calcium fluoride (refractive index n = 1.3 to 1.4), cerium fluoride (refractive index n = 1.6), aluminum fluoride (refractive index n = 1.3), aluminum oxide (refractive index n) = 1.6) and high refractive index, titanium dioxide (refractive index n = 2.4), zirconium dioxide (refractive index n = 2.0), zinc sulfide (refractive index n = 2.3). ), Zinc oxide (refractive index n = 2.1), indium oxide (refractive index n = 2.0), cerium dioxide (refractive index n = 2.3), tantalum oxide (refractive index n = 2.1). It is a composite layer in which one of them is laminated with a predetermined film thickness. This inorganic oxide vapor deposition layer can also provide two or more layers which consist of said combination.

Next, as described above, any one of paper, synthetic paper, and plastic film can be used for the label base layer (3). Specifically, in the case of paper, coated paper coated with polyvinyl (PVA) can be preferably used. In the case of synthetic paper, specific examples of the thermoplastic resin that is the material of the synthetic paper include polypropylene, polyethylene having a density of 0.880 to 0.965 g / cm ² , polystyrene, polyacrylonitrile, polyvinyl chloride, polyethylene. Examples include terephthalate, polyamide, and polycarbonate. Among these thermoplastic resins, a polypropylene resin coextruded film containing titanium oxide in the core layer is particularly preferable. Furthermore, in the case of a plastic film, it is preferable to use a biaxially stretched polystyrene film (OPS) or a biaxially stretched polyethylene terephthalate film (OPET).

  Next, a heat sealant coat layer (4) can be formed on the back surface of the label base material layer (3). As the heat sealant coating layer (4), by using a coating layer made of a solvent-based or water-based dispersion type urethane resin, it is necessary to apply a coating agent by heating compared to a resin solution type heat seal varnish or hot melt. The resin has a higher molecular weight than that of the resin solution type heat seal varnish, and can exert adhesive force at a low coating amount. Furthermore, since the adhesive can be applied at a low coating amount, the heat of drying of the coating agent can be reduced, and the curling due to the heat effect on the label substrate can be suppressed.

  Further, it can be adhered to a container having a wide resin structure such as PS, PP, and PE, and has good adhesion to a different resin substrate. Furthermore, since the resin cohesive force is also high, a strong adhesive force can be exhibited between the container / coating layer / label substrate layer. Furthermore, the tackiness of the resin is low and the blocking resistance is good compared to EVA, which is versatile as an adhesive resin. In addition, the solvent adsorption is low as compared with vinyl chloride and polyamide-based ink resins, and blocking due to residual solvent can be avoided.

  Hereinafter, the in-mold label according to the present invention will be described in more detail with specific examples, but is not limited thereto.

<Example 1>
Of the surface base material layer (1) / shape-retaining layer (2) / label base material layer (3) which is the basic structure of the in-mold label of the present invention (see FIG. 1), the surface base material layer (1) is A printing layer (5) is provided on the surface of a biaxially stretched polyethylene terephthalate film (PET) (1a) having a thickness of 38 μm by a gravure printing method, and a polypropylene resin (PP) is extruded on the back surface of the PET by melt extrusion using a lamination apparatus. A hologram embossing resin layer (1b) having a thickness of 20 μm was laminated. Next, the relief of the hologram is transferred onto the hologram embossing resin layer (1b) in the order of heating, pressurization, cooling, and peeling, overlaid on a separately produced uneven press stamper for producing a hologram, and a transmission type A hologram was produced. Next, an aluminum vapor deposition layer (1c) having a film thickness of 40 nm was formed on the uneven surface of the hologram embossing resin layer (1b) by vacuum vapor deposition to complete a reflection hologram.

That is, the surface base layer (1) is a hologram processed film [printing ink layer (5) / polyethylene terephthalate film (PET) layer, 38 μm (1a) / hologram embossed polypropylene resin (PP) layer, 20 μm (1b) / Aluminum deposition layer, 40 nm (1c)]. Subsequently, an aluminum foil (AL) having a thickness of 15 μm is laminated as a shape-retaining layer (2) on the surface of the aluminum vapor-deposited layer (1c), and a biaxially stretched polycrystal having a thickness of 30 μm is further formed as a label substrate layer (3). A polystyrene film (OPS) was laminated to produce a laminated material for an in-mold label. The base material layer (1) / shape-retaining layer (2) / label base material layer (3) is laminated between the base materials using a polyurethane adhesive as an adhesive layer (not shown). Laminated by the method.

  The roll-shaped laminated material thus obtained is cut into an arbitrary size to form a single sheet, and then punched into a label having an arbitrary shape and size by a flat plate punching machine used for paper machine processing. Processing was performed, and the label was inserted into a PS injection in-mold molding machine to perform in-mold molding. (Note that it is possible to perform punching into a label having an arbitrary shape and size without cutting the roll-shaped laminated material.)

<Example 2>
In Example 1, an aluminum foil (AL) having a thickness of 9 μm was used as the shape retaining layer (2), and a biaxially stretched polyethylene terephthalate film (PET) having a thickness of 12 μm was further used as the label base layer (3). A laminated material for an in-mold label was produced in the same manner as in Example 1 except that a laminated material in which an EVA heat sealant (HS agent) coat layer (4) having a thickness of 5 μm was laminated on the back surface was used.

  The laminated material thus obtained was punched into a label with an arbitrary shape and size, and PS injection in-mold molding was performed.

<Example 3>
In Example 1, an aluminum foil (AL) having a thickness of 25 μm is used as the shape-retaining layer (2), and a PP synthetic paper having a thickness of 60 μm (manufactured by YUPO Corporation) is used as the label base layer (3). , Trade name: YUPO (registered trademark)] was used in the same manner as in Example 1 to prepare a laminated material for an in-mold label.

  The laminated material thus obtained was punched into a label with an arbitrary shape and size, and PP injection in-mold molding was performed.

  Below, the comparative example of this invention is demonstrated.

<Comparative Example 1>
In Example 1, the shape-retaining layer (2) was not provided, and a biaxially stretched polystyrene film (OPS) having a thickness of 30 μm was used as the label base layer (3). A laminated material for in-mold label was produced.

  The laminated material thus obtained was punched into a label with an arbitrary shape and size, and PS injection in-mold molding was performed.

<Comparative example 2>
In Example 1, the shape retaining layer (2) is not provided, and the EVA base heat sealant having a thickness of 5 μm is provided on the back surface of the biaxially stretched polyethylene terephthalate film (PET) having a thickness of 12 μm as the label base material layer (3). (HS agent) A laminated material for an in-mold label was produced in the same manner as in Example 1 except that the laminated material on which the coating layer (4) was laminated was used.

  The laminated material thus obtained was punched into a label with an arbitrary shape and size, and PS injection in-mold molding was performed.

<Comparative Example 3>
In Example 1, the shape retaining layer (2) is not provided, and a PP synthetic paper [manufactured by YUPO Corporation, trade name: YUPO (registered trademark)] having a thickness of 60 μm is used as the label base layer (3). A laminated material for an in-mold label was produced in the same manner as in Example 1 except that it was used.

  The laminated material thus obtained was punched into a label with an arbitrary shape and size, and PP injection in-mold molding was performed.

  In Example 1, an aluminum foil (AL) having a thickness of 7 μm is used as the shape-retaining layer (2), and a PP synthetic paper having a thickness of 60 μm (manufactured by YUPO Corporation) is used as the label base layer (3). , Trade name: YUPO (registered trademark)] was used in the same manner as in Example 1 to prepare a laminated material for an in-mold label.

  The laminated material thus obtained was punched into a label with an arbitrary shape and size, and PP injection in-mold molding was performed.

<Evaluation>
The curl height when the in-mold label made of each of the laminated materials obtained in Examples 1 to 3 and Comparative Examples 1 to 4 was pulled out and the molding position deviation when performing the in-mold molding were measured. . The results are shown in Table 1.

<Evaluation method>
As for the curl height, the curled inner surface of the label was pulled out and allowed to stand on top, and the height of the label edge was measured. As a result, when it was less than 5 mm, it was evaluated as ◯ when it was 5 mm or more. As for the molding displacement, the positional displacement of the label end joint of the molded product was measured. As a result, if it was less than 1 mm, it was evaluated as ◯ if it was 1 mm or more.

表１には、各々の実施例、比較例で得られたインモールドラベルの抜き上がり時のカール高さ、およびインモールド成形を行なった際の成形位置ズレの測定結果を記した。

Table 1 shows the curl height when the in-mold label obtained in each of the examples and comparative examples was pulled out, and the measurement result of the molding position deviation when in-mold molding was performed.

<Evaluation results>
From Table 1, the in-mold labels of Examples 1, 2, and 3 have both the curl height and molding deviation within the standard values, which is a good result and can suppress temperature and humidity-dependent curling. In addition, the temperature management during the distribution of the label, the distribution management such as packing with the barrier packaging material became very easy, and the in-mold molding suitability was also excellent.

It is a sectional side view which shows one Example of the laminated constitution of the in-mold label which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Surface base material layer 1a ... Stretched film 1b ... Hologram embossing resin layer 1c ... Light reflection layer 2 ... Shape retention layer 3 ... Label base material layer 4 ... Heat Sealing agent coating layer 5 ... Printing ink layer 6 ... Film layer

Claims (10)

  At least an in-mold label made of a laminated material in which a surface base material layer, a shape retaining layer, and a label base material layer are sequentially laminated, and the surface base material layer sequentially comprises a stretched film, a hologram embossing resin layer, and a light reflecting layer. An in-mold characterized in that it is a laminated hologram processing film (decorative film), wherein the shape retaining layer is made of an aluminum foil, and the label base material layer is any one of paper, synthetic paper, and plastic film. label.   The in-mold label according to claim 1, wherein the thickness of the aluminum foil is within a range of 9 to 30 µm.   The in-mold label according to claim 1, wherein a heat sealant coat layer is formed on the back surface of the label base material layer.   The in-mold label according to any one of claims 1 to 3, wherein a printing ink layer is formed on a front surface or a back surface of the stretched film of the front base material layer.   The in-mold label according to any one of claims 1 to 4, wherein the stretched film is a polyethylene terephthalate film.   The in-mold label according to claim 1, wherein the hologram embossing resin layer is a thermoplastic resin.   The in-mold label according to any one of claims 1 to 6, wherein the light reflection layer is a metal or an inorganic oxide vapor deposition layer having a different refractive index.   The in-mold label according to any one of claims 1 to 7, wherein the paper is coated paper coated with polyvinyl (PVA).   The in-mold label according to any one of claims 1 to 8, wherein the synthetic paper is a polypropylene resin coextruded film containing titanium oxide in a core layer.   The in-mold label according to any one of claims 1 to 9, wherein the plastic film is a biaxially stretched polystyrene film (OPS) or a biaxially stretched polyethylene terephthalate film (OPET).

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