Manufacturing method of laminates

Abstract

To provide a laminate production method capable of achieving variable printing in which expression properties has been enhanced.SOLUTION: There is provided a production method of a laminate 20 comprising: a step S1 for preparing a laminate precursor 10 including a substrate 11, and an inorganic flake-containing ink layer 13 on the substrate 11; and a step S2 for radiating an energy ray 15 to the laminate precursor 10. The inorganic flake-containing ink layer 13 includes inorganic flake. In the step for radiating the energy ray 15, a direction of the inorganic flake on a position where the energy ray 15 is radiated is varied.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a laminate.

Background Art

[0002] When printing an expiration date or the like on a label, for example, a method of printing ink on the surface of a label substrate by a method such as an inkjet printer or a thermal printer is the mainstream.

[0003] However, the printing may disappear due to rubbing of the ink on the label during transportation of the product to which the label is attached.

[0004] Therefore, there is a demand for printing that is difficult to disappear after once printed for the printing of labels. As one method to meet this demand, a laser printing method of printing by irradiating laser light has been studied.

[0005] In the laser printing method, laser printing can be provided on the outer surface of the label by irradiating laser light from the outside of the label. Also, there is a demand for shielding the laser printing on the inner side of the label so that it cannot be seen from the outside of the label by providing laser printing on the inner surface of the label by irradiating laser light from the inside of the label.

[0006] For example, in Patent Document 1, a method of performing printing on a laminated film for laser printing in which a white ink layer, a printing agent layer, a printed pattern layer, and a plastic film are laminated in this order from the side irradiated with laser light is disclosed by irradiating laser light from the side opposite to the side where the printed pattern layer can be visually recognized.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

[0008] In the method described in Patent Document 1, printing is performed by the printing agent layer turning black when irradiated with laser light, and the printing is visible due to the contrast between the blackened resin portion and the resin portion that did not blacken. The method described in Patent Document 1 is an excellent method that enables variable printing (the ability to change the printed content) such as QR codes (registered trademark) and random number printing. However, the method described in Patent Document 1 only allows for expression through temperature-induced color change in terms of print expressiveness, and the print expressiveness is insufficient when used for decorative purposes. [Means for solving the problem]

[0009] According to the embodiments disclosed herein, a method for manufacturing a laminate is provided, comprising the steps of preparing a laminate precursor comprising a substrate and an inorganic flake-containing ink layer on the substrate, and irradiating the laminate precursor with energy rays, wherein the inorganic flake-containing ink layer contains inorganic flakes, and in the step of irradiating with energy rays, the orientation of the inorganic flakes at the location irradiated with energy rays changes. [Effects of the Invention]

[0010] According to the embodiments disclosed herein, it is possible to provide a method for manufacturing a laminate that enables variable printing with improved expressiveness compared to the method described in Patent Document 1. [Brief explanation of the drawing]

[0011] [Figure 1] This is a flowchart of the manufacturing method for the laminate of the embodiment. [Figure 2] This is a schematic cross-sectional view of an example of a laminate precursor used in the manufacturing method of the laminate according to the embodiment. [Figure 3] Figure 2 is a schematic cross-sectional view illustrating an example of the process of irradiating the laminate precursor with energy rays. [Figure 4]This is a schematic plan view of a laminate manufactured by the manufacturing method of the embodiment, as seen from the substrate side. [Figure 5] Figure 4 is a schematic plan view of the laminated substrate as seen from the substrate side after thermal shrinkage. [Figure 6] This is a schematic cross-sectional view illustrating another example of the process of irradiating a laminate precursor with energy rays. [Modes for carrying out the invention]

[0012] The embodiments will be described below. In the drawings used to describe the embodiments, the same reference numerals represent the same part or a corresponding part.

[0013] Figure 1 shows a flowchart of the manufacturing method of the laminate according to the embodiment. As shown in Figure 1, the manufacturing method of the laminate according to the embodiment includes a step S1 for preparing a laminate precursor and a step S2 for irradiating the laminate precursor with energy rays. By going through steps S1 and then step S2, the final product, the laminate, can be manufactured.

[0014] <Steps for preparing the laminate precursor> Step S1 for preparing the laminate precursor can be carried out, for example, by preparing the laminate precursor 10 shown in the schematic cross-sectional view of Figure 2. The steps for preparing the laminate precursor 10 can include, for example, the steps of preparing a substrate 11, forming a base ink layer 12 on the substrate 11, forming an inorganic flake-containing ink layer 13 on the base ink layer 12, and forming a heat-generating layer 14 on the inorganic flake-containing ink layer 13. The laminate precursor 10 thus prepared includes a heat-generating layer 14 that faces the inorganic flake-containing ink layer 13 and is located on the opposite side of the inorganic flake-containing ink layer 13 from the substrate 11.

[0015] (Preparation of the base material) The process of preparing the substrate 11 can be carried out, for example, by preparing a plastic film capable of supporting at least the inorganic flake-containing ink layer 13. The plastic film constituting the substrate 11 may be transparent. When the substrate 11 is transparent, the total light transmittance of the substrate 11 is preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more. The total light transmittance can be measured, for example, by JIS K 7105 (Test Methods for Optical Properties of Plastics).

[0016] As the plastic film constituting the base material 11, for example, a plastic film can be prepared that contains polyester resins (polyethylene terephthalate, polyethylene naphthalate, polylactic acid, PETG (a polyester resin obtained by substituting some or all of the ethylene glycol, which is the glycol component of polyethylene terephthalate, with cyclohexanedimethanol, neopentyl glycol, etc.)), polystyrene resins (polystyrene, styrene-butadiene copolymer, etc.), polyolefin resins (polyethylene, polypropylene, cyclic polyolefin resins, etc.), polyvinyl chloride resins, polyamide resins, aramid resins, polyimide resins, polyphenylene sulfide resins, or acrylic resins. The plastic film constituting the base material 11 may contain one of these resins, or it may contain two or more of these resins.

[0017] As the plastic film constituting the base material 11, for example, a heat-shrinkable plastic film (shrink film) or a non-heat-shrinkable plastic film can be prepared. Among them, it is preferable to prepare a heat-shrinkable plastic film. In this case, by heating the laminate manufactured by the manufacturing method of the laminate of the embodiment to shrink the base material 11, the contrast of irregular reflection between the irradiated portion and the non-irradiated portion of the energy ray described later in the laminate is increased, so that the expressiveness of variable printing tends to be improved. The heat shrinkage rate in the main shrinkage direction of the heat-shrinkable plastic film can be, for example, 40% or more and 95% or less, and preferably 50% or more and 90% or less when the heat-shrinkable plastic film is immersed in hot water at 90°C for 10 seconds.

[0018] The plastic film prepared as the base material 11 may be a single-layer plastic film composed of one layer, or a multi-layer plastic film composed of two or more layers. Also, the thickness of the plastic film prepared as the base material 11 can be, for example, 5 μm or more and 100 μm or less.

[0019] (Step of forming an undercoat ink layer on the base material) The step of forming the undercoat ink layer 12 on the base material 11 can be performed, for example, by printing an ink for forming the undercoat ink layer 12 (hereinafter referred to as "undercoat ink"), which is a precursor of the undercoat ink layer 12, on the base material 11 and then drying it. As the undercoat ink, for example, an oil-based ink containing an organic solvent and a resin, or an aqueous ink containing an aqueous solvent and a resin (including both cases where the resin is dissolved in the aqueous solvent and where the resin is not dissolved in the aqueous solvent (emulsion)) can be used. The printing of the undercoat ink can be performed, for example, by flexographic printing, gravure printing, screen printing, inkjet printing, or liquid toner printing. The drying of the undercoat ink can be performed, for example, by volatilizing at least a part of the solvent of the undercoat ink. The thickness of the undercoat ink layer 12 can be, for example, about 0.1 μm or more and 10 μm or less.

[0020] As the resin contained in the undercoat ink, for example, an acrylic resin, a urethane resin, a polyester resin, a polyamide resin, a cellulose resin, a vinyl chloride resin, a vinyl acetate resin, a polyolefin resin (for example, a polyethylene resin or a polybutadiene resin, etc.), an isocyanate resin, a rosin resin, a polyvinyl alcohol resin (PVA resin), or an imine resin, etc. can be used, but a resin that can be softened by the temperature rise due to the irradiation of energy rays described later can be used. As the resin contained in the undercoat ink, for example, a resin having a lower softening temperature than the resin constituting the inorganic flake-containing ink layer 13 may be used.

[0021] It is preferable to use a thermoplastic resin as the resin contained in the undercoat ink. In this case, as described later, the orientation of the inorganic flakes in the inorganic flake-containing ink layer 13 tends to be easily changed by the irradiation of energy rays. As the thermoplastic resin contained in the undercoat ink, for example, an acrylic resin, a urethane resin or a cellulose resin, etc. can be used. As the undercoat ink, for example, a colorless transparent or colored transparent ink can be used from the viewpoint of ensuring the visibility of the inorganic flake-containing ink layer 13 from the substrate 11 side.

[0022] (Step of forming an inorganic flake-containing ink layer on the undercoat ink layer) The process of forming an inorganic flake-containing ink layer 13 on a base ink layer 12 can be carried out, for example, by printing an ink for forming the inorganic flake-containing ink layer 13 (hereinafter referred to as "inorganic flake-containing ink"), which serves as a precursor to the inorganic flake-containing ink layer 13, onto the base ink layer 12 and then drying it. As the inorganic flake-containing ink, for example, an ink containing inorganic flakes, a solvent such as an organic solvent or an aqueous solvent, and a resin can be used. Printing of the inorganic flake-containing ink can be carried out, for example, by flexographic printing, gravure printing, screen printing, inkjet printing, or liquid toner printing. Drying of the inorganic flake-containing ink can be carried out, for example, by volatilizing at least a portion of the solvent in the inorganic flake-containing ink. The inorganic flake-containing ink layer 13 may be, for example, a layer that has a luminosity due to the inorganic flakes. Furthermore, the inorganic flake-containing ink layer 13 may be, for example, an opaque layer (a layer that is difficult to see through to the back side). When, for example, aluminum flakes, which will be described later, are used as the inorganic flakes, the inorganic flake-containing ink layer 13 may have a metallic appearance such as silver and be an opaque layer.

[0023] As the inorganic flakes contained in the inorganic flake-containing ink layer 13, for example, aluminum flakes, brass flakes, metal flakes other than aluminum flakes, or mica flakes or other metal oxide flakes can be used. When using aluminum flakes as the inorganic flakes, it is preferable to use aluminum flakes produced by the ordinary ball mill method or aluminum flakes produced by the vapor deposition method. These inorganic flakes may be used individually or mixed together as the inorganic flakes contained in the inorganic flake-containing ink layer 13.

[0024] The shape of the inorganic flakes may be, for example, flattened. The aspect ratio ((thickness of inorganic flakes) / (length of the surface of inorganic flakes)), which is the ratio of the thickness of the inorganic flakes (maximum thickness of inorganic flakes) to the length of the surface of the flattened inorganic flakes (the longest length of the surface of the inorganic flakes), can be, for example, 1 / 5 or more and 1 / 1000 or less, preferably 1 / 10 or more and 1 / 100 or less. The flattened inorganic flakes may have, for example, smooth surfaces. If the flattened inorganic flakes have smooth surfaces, for example, the smooth surfaces of the inorganic flakes can be arranged so that they face substantially the same direction.

[0025] Examples of resins that can be used in inorganic flake-containing inks include acrylic resins, urethane resins, polyester resins, polyamide resins, cellulose resins, vinyl chloride resins, vinyl acetate resins, polyolefin resins (e.g., polyethylene resins or polybutadiene resins), isocyanate resins, rosin resins, polyvinyl alcohol resins (PVA resins), or imine resins. These resins may be used individually or mixed in combination as the resins contained in inorganic flake-containing inks. From the viewpoint of more easily changing the orientation of the inorganic flakes at the location irradiated with the energy rays described later, it is preferable to use a thermoplastic resin as the resin contained in the inorganic flake-containing ink.

[0026] (A process of forming a heat-generating layer on an ink layer containing inorganic flakes) The step of forming a heat-generating layer 14 on an inorganic flake-containing ink layer 13 can be carried out, for example, by printing an ink for forming the heat-generating layer 14 (hereinafter referred to as "heat-generating ink"), which will serve as a precursor for the heat-generating layer 14, onto the inorganic flake-containing ink layer 13 and then drying it. As the heat-generating ink, an ink containing an absorbent capable of absorbing energy rays (described later), a solvent such as an organic solvent or an aqueous solvent, and a resin can be used. The heat-generating ink can be printed, for example, by flexographic printing, gravure printing, screen printing, inkjet printing, or liquid toner printing. The heat-generating ink can be dried, for example, by volatilizing at least a portion of the solvent in the heat-generating ink.

[0027] As absorbents included in the heat-generating ink, for example, ultraviolet absorbers, infrared absorbers, near-infrared absorbers, or carbon black can be used. As resins included in the heat-generating ink, for example, binder resins similar to those included in inorganic flake-containing inks can be used.

[0028] <Process of irradiating the laminate precursor with energy beams> Step S2, in which the laminate precursor 10 is irradiated with energy rays 15, can be carried out, for example, by irradiating the heat-generating layer 14 of the laminate precursor 10 with energy rays 15, as shown in the schematic cross-sectional view of Figure 3. Figure 3 shows an example in which the energy rays 15 are irradiated from the substrate 11 side, but the energy rays 15 may also be irradiated from the heat-generating layer 14 side. However, it is preferable to irradiate the energy rays 15 from the substrate 11 side.

[0029] As the energy beam 15, for example, laser light, microwaves (light with a wavelength of 1 mm to 1 m), ultraviolet light (light with a wavelength of 10 nm to 400 nm), visible light (light with a wavelength of 400 nm to 700 nm), or infrared light (light with a wavelength of 800 nm to less than 1000 nm) can be used for irradiation. Among these, it is preferable to irradiate with laser light as the energy beam 15. As the laser light, for example, ultraviolet laser light (wavelength of 10 nm to 400 nm), YAG laser light (wavelength of 1.064 μm), fiber laser light (wavelength of 1030 nm to 1070 nm), or infrared laser light (wavelength of 780 nm to 16 μm) can be used for irradiation.

[0030] In the process of irradiating the laminate precursor 10 with energy rays 15, the absorber in the heat-generating layer 14 of the laminate precursor 10 absorbs the energy rays 15 and generates heat, heating the heat-generating layer 14, and the heat from the heat-generating layer 14 is transferred to the inorganic flake-containing ink layer 13 and the base ink layer 12. The heat transferred to the base ink layer 12 causes the base ink layer 12 to soften and deform, creating irregularities at the interface between the base ink layer 12 and the inorganic flake-containing ink layer 13, and changing the orientation of the inorganic flakes in the inorganic flake-containing ink layer 13 on the irregularities on the surface of the base ink layer 12. Subsequently, the base ink layer 12 and the inorganic flake-containing ink layer 13 are cooled while the orientation of the inorganic flakes in the inorganic flake-containing ink layer 13 has changed, thereby manufacturing the final product, the laminate 20.

[0031] When the entire laminate precursor 10 is irradiated with energy rays 15, the orientation of the inorganic flakes in the inorganic flake-containing ink layer 13 of the final product laminate 20 changes at the irradiated locations compared to before irradiation with energy rays 15. Conversely, when the laminate precursor 10 is partially irradiated with energy rays 15, the orientation of the inorganic flakes in the inorganic flake-containing ink layer 13 of the final product laminate 20 remains unchanged in areas not irradiated with energy rays 15, but only the orientation of the inorganic flakes in the inorganic flake-containing ink layer 13 at the irradiated locations changes. Therefore, in both cases, when the entire laminate precursor 10 is irradiated with energy rays 15 and when only a part of the laminate precursor 10 is irradiated with energy rays 15, when the final product, the laminate 20, is viewed from the substrate 11 side, it is possible to create an effect by generating diffuse reflection at the irradiated area of ​​the energy rays 15. This enables variable printing of the final product, the laminate 20, with improved expressiveness compared to the method described in Patent Document 1. For example, when only a part of the laminate precursor 10 is irradiated with energy rays 15, it is possible to form two regions with different brightness levels: the irradiated area and the unirradiated area.

[0032] Figure 4 shows a schematic plan view of the laminate 20 manufactured by the manufacturing method of the embodiment, as viewed from the substrate 11 side. Figure 5 shows a schematic plan view of the laminate 20 shown in Figure 4 as viewed from the substrate 11 side after the substrate 11 has been heat-shrunk. As is clear from the comparison between Figure 4 and Figure 5, by further performing the step of heat-shrinking the substrate 11 of the laminate 20, the design of the inorganic flake-containing ink layer 13 can be displayed more clearly, thereby making the decorative properties of the final product, the laminate 20, even better. The heat shrinkage rate of the substrate 11 of the laminate 20 in the main shrinkage direction during the heat-shrinking step of the substrate 11 of the laminate 20 can be, for example, 5% or more.

[0033] In the above description, for example as shown in Figure 3, an example is described in which an energy ray is irradiated onto a laminate precursor 10 in which a base material 11, a base ink layer 12, an inorganic flake-containing ink layer 13, and a heating layer 14 are stacked in this order from bottom to top. However, as shown in the schematic cross-sectional view of Figure 6, for example, an energy ray may be irradiated onto a laminate precursor 10 in which a heating layer 14, which also serves as the base ink layer 12, and an inorganic flake-containing ink layer 13 are stacked in this order from bottom to top. Furthermore, in the laminate precursor 10 shown in Figures 3 and 6, for example, at least one layer selected from the group consisting of the base ink layer 12, the inorganic flake-containing ink layer 13, and the heating layer 14 may be provided on a part of the base material 11. [Industrial applicability]

[0034] The final product, the laminate 20, can be used as a label such as a shrink label, wrap label, thermal label, tack label, or in-mold label, or as a film packaging such as an overwrap package or pouch package, but it is preferable to use it as a shrink label or overwrap shrink package that can be heat-shrinked. In this case, the step of attaching the shrink label or overwrap shrink package to an article by heat-shrinking it may be the same as the step of heat-shrinking the base material 11 described above. In this case, an article with the final product, the laminate 20, attached can be obtained. When the final product, the laminate 20, is used as a shrink label, it is preferable to have a method for manufacturing an article with the laminate 20 attached, which includes, in this order, the steps of preparing a laminate precursor 10, forming the laminate precursor 10 into a cylindrical shape, manufacturing the laminate 20 by irradiating the cylindrical laminate precursor 10 with energy rays 15, and attaching the laminate 20 to an article by heat-shrinking it.

[0035] As described above, the embodiments have been explained, but it has been planned from the outset that the configurations of each of the embodiments described above may be combined as appropriate.

[0036] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended. [Explanation of Symbols]

[0037] 10 Laminate precursor, 11 Substrate, 12 Undercoat ink layer, 13 Inorganic flake-containing ink layer, 14 Heat-generating layer, 20 Laminate.

Claims

1. A step of preparing a laminate precursor comprising a substrate and an inorganic flake-containing ink layer on the substrate, The process includes irradiating the laminate precursor with energy rays, The aforementioned inorganic flake-containing ink layer contains inorganic flakes, In the process of irradiating with the energy ray, the orientation of the inorganic flakes at the location irradiated with the energy ray changes. The aforementioned inorganic flake-containing ink layer further contains resin, A method for manufacturing a laminate, wherein the resin contained in the inorganic flake-containing ink layer is a thermoplastic resin.

2. A step of preparing a laminate precursor comprising a substrate and an inorganic flake-containing ink layer on the substrate, The process includes irradiating the laminate precursor with energy rays, The aforementioned inorganic flake-containing ink layer contains inorganic flakes, In the process of irradiating with the energy ray, the orientation of the inorganic flakes at the location irradiated with the energy ray changes. A method for manufacturing a laminate, wherein the laminate precursor further comprises a heat-generating layer facing the inorganic flake-containing ink layer.

3. A step of preparing a laminate precursor comprising a substrate and an inorganic flake-containing ink layer on the substrate, The process includes irradiating the laminate precursor with energy rays, The aforementioned inorganic flake-containing ink layer contains inorganic flakes, In the process of irradiating with the energy ray, the orientation of the inorganic flakes at the location irradiated with the energy ray changes. The aforementioned substrate is a heat-shrinkable plastic film. A method for manufacturing a laminate, further comprising the step of shrinking the substrate after the step of irradiating it with energy rays.

4. A step of preparing a laminate precursor comprising a substrate and an inorganic flake-containing ink layer on the substrate, The process includes irradiating the laminate precursor with energy rays, The aforementioned inorganic flake-containing ink layer contains inorganic flakes, In the process of irradiating with the energy ray, the orientation of the inorganic flakes at the location irradiated with the energy ray changes. A method for manufacturing a laminate, wherein the laminate precursor further comprises a base ink layer between the substrate and the inorganic flake-containing ink layer.

5. The method for manufacturing a laminate according to claim 4, wherein the base ink layer includes a thermoplastic resin.

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