Printed materials and methods for manufacturing the same

Abstract

This printed matter comprises: matter to be printed having a surface subjected to printing; an oily ink layer provided on the surface; and an aqueous varnish layer provided so as to cover the oily ink layer, wherein the aqueous varnish layer includes dried matter of emulsion-type aqueous varnish obtained by combining different resins, and is formed thicker than the oily ink layer.

Description

Technical Field

[0001] The present disclosure relates to printed matter and a method for manufacturing the same.

Background Art

[0002] Conventionally, various printing methods have been developed. For example, UV offset printing and oil-based offset printing are known. In UV offset printing, a UV-curable ink containing a photoinitiator and a monomer is used. In oil-based offset printing, an oil-based ink is used, and a dedicated powder may be sprayed onto the undried oil-based ink during printing.

[0003] Each printing method has its own advantages and disadvantages, and the printing method is selected according to the use and required quality of the printed matter. UV offset printing has the advantage of being able to dry quickly and being able to be processed immediately after printing, but it has the following disadvantages. (1) It consumes a large amount of power for UV irradiation. (2) Due to the quick drying, unevenness tends to remain on the surface of the ink layer. (3) The reproducible color gamut is narrower compared to oil-based offset printing. (4) Concerns about the influence of photoinitiators on the human body have begun to arise overseas, and the number of countries that avoid using them for food packaging is increasing.

[0004] Oil-based offset printing has the advantage of having a wider color reproducible gamut than UV offset printing, but it has the following disadvantages. (1) The ink does not dry unless it is left standing for about a day after printing. (2) Since the oil-based ink hardens by oxidative polymerization while slowly moving, even if a varnish layer is formed to cover the ink layer to impart gloss, due to a phenomenon called dry-down, the smoothness of the surface of the varnish layer is lost and the gloss decreases. Patent Document 1 discloses a method for manufacturing cardboard base paper through a process of applying heat and pressure to the varnish layer using an embossing machine to perform gloss finishing (heat press processing).

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2015-117027 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] It was believed that in order to obtain glossy printed materials by oil-based offset printing, it was necessary to subsequently apply heat pressing to the oil-based ink layer and the varnish layer, as described in Patent Document 1. In other words, it was considered difficult to control the surface smoothness of the varnish layer covering the oil-based ink layer without performing heat pressing.

[0007] This disclosure provides a printed material comprising an oil-based ink layer and a varnish layer covering the same, which has excellent gloss even without heat pressing of the varnish layer during the manufacturing process, and a method for manufacturing the same. [Means for solving the problem]

[0008] The present inventors, after diligent research to efficiently produce high-gloss printed materials using oil-based inks, have completed the following invention. Specifically, the printed material according to this disclosure comprises a substrate having a surface to be printed on, an oil-based ink layer provided on this surface, and an aqueous varnish layer provided so as to cover the oil-based ink layer, wherein the aqueous varnish layer contains a dried emulsion-type aqueous varnish made from a combination of different resins and is formed to be thicker than the oil-based ink layer.

[0009] Because the water-based varnish layer is thicker than the oil-based ink layer, the surface irregularities of the oil-based ink layer can be sufficiently suppressed from affecting the surface smoothness of the water-based varnish layer. Therefore, even without performing a heat press on the water-based varnish layer, the surface of the water-based varnish layer can be made sufficiently smooth, and the surface of the water-based varnish layer has excellent gloss. By including a dried emulsion-type water-based varnish in the water-based varnish layer, it is possible to select a hard resin as at least a part of the resin, which also contributes to improving the surface smoothness of the water-based varnish layer, and consequently to improving the gloss of the varnish layer surface. After forming a coating film of emulsion-type water-based varnish, the water-based varnish layer is formed by evaporating the water contained in the coating film.

[0010] One aspect of this disclosure relates to a method for manufacturing printed materials. This manufacturing method includes the steps of forming a coating film of an emulsion-type aqueous varnish made of different resins on the surface of an oil-based ink layer, and drying the coating film to form an aqueous varnish layer containing the dried aqueous varnish on the surface of the oil-based ink layer, wherein the coating film is formed such that the aqueous varnish layer is thicker than the oil-based ink layer. [Effects of the Invention]

[0011] According to this disclosure, a printed article comprising an oil-based ink layer and a varnish layer provided to cover it, which has excellent gloss even without heat pressing on the varnish layer during the manufacturing process, and a method for manufacturing the same are provided. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a schematic cross-sectional view showing one embodiment of the printed material relating to this disclosure. [Figure 2] Figure 2 is a schematic cross-sectional view showing another embodiment of the printed material relating to this disclosure. [Modes for carrying out the invention]

[0013] The embodiments of this disclosure will be described in detail below. However, the present invention is not limited to the embodiments described below.

[0014] Figure 1 is a schematic cross-sectional view showing a printed material according to this embodiment. The printed material 10 shown in this figure comprises a substrate 1 having a surface 1a to which printing is applied, an oil-based ink layer 3 provided on the surface 1a, and an aqueous varnish layer 5 provided so as to cover the oil-based ink layer 3. The aqueous varnish layer 5 is formed using an emulsion-type aqueous varnish and is formed to be thicker than the oil-based ink layer 3.

[0015] The substrate 1 is, for example, paper. Specific examples of paper include fine paper, special fine paper, coated paper, art paper, cast coated paper, imitation paper, and kraft paper. The mass per unit area of ​​the paper is, for example, 20-500 g / m². 2 Or 25-400g / m 2 It is acceptable as long as it is within that range. The substrate 1 may be composed of a composite material including, for example, paper and a resin material.

[0016] The oil-based ink layer 3 is a layer formed by offset printing using oil-based ink. The thickness of the oil-based ink layer 3 (thickness T3 in Figure 1) is preferably 1.5 μm or less, more preferably 1.3 μm or less, and even more preferably 1.1 μm or less. By having a thickness of 1.5 μm or less, the surface irregularities of the oil-based ink layer 3 can be sufficiently suppressed from affecting the surface smoothness of the water-based varnish layer 5. Therefore, even if the water-based varnish layer 5 is not subjected to heat pressing, the surface of the water-based varnish layer 5 can be made sufficiently smooth. The lower limit of the thickness of the oil-based ink layer 3 is, for example, 0.5 μm. By using a concentrated type (high-concentration type) oil-based ink, a clear oil-based ink layer 3 can be formed even if the thickness of the oil-based ink layer 3 is in the range of 0.5 to 1.5 μm. Concentrated type oil-based inks have a low solvent content. Therefore, using concentrated type oil-based inks also has the effect of shortening the drying time. Furthermore, a concentrated oil-based ink refers to an ink in which the mass of the solvent relative to the total mass of the oil-based ink is 60% by mass or less. The mass of the solvent may be 30% by mass or more, and is preferably 40-50% by mass.

[0017] The thickness of the oil-based ink layer 3 can be determined using an optical microscope and interference spectroscopy, which utilizes the phenomenon of light interference. The thickness of the oil-based ink layer 3 may also be determined by observing a cross-section of the printed material 10 or an intermediate product (for example, before the formation of the aqueous varnish layer 5) with an optical microscope. As the oil-based ink, for example, vegetable oil ink can be used. Biomass ink may be used instead of vegetable oil ink. Biomass ink is an ink that contains a colorant and a cured product of a polyol and an isocyanate compound, wherein at least one of the polyol and the isocyanate compound contains a biomass-derived component.

[0018] The aqueous varnish layer 5 is a layer formed by an offset printing method using an emulsion-type aqueous varnish. The aqueous varnish layer 5 contains a dried product of an aqueous varnish containing an emulsion in which different resins are combined. Examples of the resins contained in the aqueous varnish layer 5 include acrylic resins, urethane resins, and silicone resins. The combined resins may be, for example, chemically bonded, or may be contained in the aqueous varnish as separate resins. There is no limitation on the combination of resins, but for example, at least two combinations selected from acrylic resins, urethane resins, and silicone resins may be used.

[0019] As described above, the aqueous varnish layer 5 is formed thicker than the oil-based ink layer 3. The thickness of the aqueous varnish layer 5 (thickness T5 in FIG. 1) is preferably 2.5 μm or more, more preferably 2.7 μm or more, and still more preferably 2.9 μm or more. When the thickness of the aqueous varnish layer 5 is 2.5 μm or more, it is possible to sufficiently suppress the unevenness on the surface of the oil-based ink layer 3 from affecting the surface smoothness of the aqueous varnish layer 5. Therefore, even if no hot pressing process is performed on the aqueous varnish layer 5, the surface of the aqueous varnish layer 5 can be made sufficiently smooth. The upper limit of the thickness of the aqueous varnish layer 5 is, for example, 5.0 μm. When the thickness of the aqueous varnish layer 5 is 5.0 μm or less, it tends to be possible to achieve both high quick-drying properties in the process of forming the aqueous varnish layer 5 and high surface smoothness of the surface 5a of the aqueous varnish layer 5. The thickness of the aqueous varnish layer 5 can also be determined by an interference spectroscopy method using an optical microscope and utilizing the interference phenomenon of light. The thickness of the aqueous varnish layer 5 may also be determined by observing a cross-section of the printed matter 10 with an optical microscope.

[0020] The ratio (T5 / T3) of the thickness T5 of the aqueous varnish layer 5 to the thickness T3 of the oil-based ink layer 3 is preferably 3 / 2 to 7 / 2, 8 / 5 to 3 / 1, 5 / 3 to 3 / 1, or 5 / 3 to 5 / 2, and may also be 5 / 3 to 2 / 1, 2 / 1 to 5 / 2, or 8 / 5 to 5 / 2. When the value of T5 / T3 is within this range, it is possible to sufficiently suppress the unevenness on the surface of the oil-based ink layer 3 from affecting the surface smoothness of the aqueous varnish layer 5.

[0021] The surface 5a of the aqueous varnish layer 5 is sufficiently smooth and has excellent gloss. The glossiness of the surface 5a is preferably 60 or more, more preferably 65 or more, and still more preferably 70 or more. The upper limit of the glossiness is, for example, 85. The glossiness referred to here means a value measured at an incident angle of 60 degrees in accordance with the method described in JIS Z8741-1997. The glossiness of the surface 5a can be adjusted to some extent by adjusting the components of the aqueous varnish layer 5 (for example, increasing the solid content ratio) in addition to the smoothness of the surface 5a.

[0022] The aqueous varnish layer 5 preferably has excellent abrasion resistance. To improve the abrasion resistance of the aqueous varnish layer 5, wax may be used as an additive. From the viewpoint of the handling property of the printed matter 10, the surface 5a of the aqueous varnish layer 5 preferably has a small coefficient of friction. To reduce the coefficient of friction of the surface 5a, silicone resin or wax may be used as an additive. The static coefficient of friction of the surface 5a is preferably 0.1 to 0.3, and may be 0.2 to 0.3 or 0.1 to 0.2. The dynamic coefficient of friction of the surface 5a is preferably 0.05 to 0.15, and may be 0.1 to 0.15 or 0.05 to 0.10.

[0023] <Method for manufacturing a printed matter> The method for manufacturing the printed matter 10 includes the following steps. (A) A step of forming a coating film (not shown) of an emulsion-type aqueous varnish in which different resins are combined on the surface of the oil-based ink layer 3. (B) A step of drying the coating film to form an aqueous varnish layer 5 containing a dried product of the aqueous varnish on the surface of the oil-based ink layer 3. The aqueous varnish layer is formed through the step of drying the coating film. By forming the aqueous varnish layer 5 thicker than the oil-based ink layer 3, a printed matter 10 having excellent gloss can be obtained without performing heat pressing on the aqueous varnish layer 5 in the manufacturing process of the printed matter 10.

[0024] Although embodiments of the present disclosure have been described in detail above, the present invention is not limited to the above embodiments. For example, in the above embodiments, an example was given in which the oil-based ink layer 3 is formed so as to cover the entire surface 1a of the substrate 1, but the oil-based ink layer 3 may be formed partially on the surface 1a. The printed material 20 shown in Figure 2 comprises the substrate 1, an oil-based ink layer 13 composed of a plurality of layers 13a partially formed on the surface 1a, and an aqueous varnish layer 15 provided so as to cover the oil-based ink layer 13 and the surface 1a. In this embodiment, the thickness of the aqueous varnish layer 15 (thickness T in Figure 2) 15 ) is the thickness of the oil-based ink layer 13 (thickness T in Figure 2). 13 It is formed to be thicker than ). Note that the thickness of the water-based varnish layer 15 (T 15 As shown in Figure 2, ) represents the distance from the surface 13b of the oil-based ink layer 13 to the surface 15a of the water-based varnish layer 15. It is preferable that the oil-based ink layer and the water-based varnish layer be formed using a roll method. However, these layers may also be formed using a chamber method instead of a roll method.

[0025] In the above embodiment, a method for manufacturing the printed material 10 without performing a heat press process was described. However, a heat press process (a process of heating and applying pressure to the surface of the water-based varnish layer) may be performed on the water-based varnish layer during the manufacturing process of the printed material. By performing a heat press process, the surface of the water-based varnish layer can be made even smoother, and the reflective haze can be reduced while maintaining almost the same gloss as before the heat press. In other words, the effect of increasing the mirror-like surface quality while maintaining excellent gloss can be achieved. [Examples]

[0026] The present disclosure will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0027] The following materials were prepared to create the printed sections for the examples and comparative examples. (1) Printing material • Coated cardboard (manufactured by Rengo Co., Ltd., 310g / m²) 2) (2) Ink • Oil-based ink: TOYO KING® NEX series (manufactured by Toyo Ink Co., Ltd.) • UV-curing ink: FD Carton X (manufactured by Toyo Ink Co., Ltd.) (3) Varnish • Water-based varnish: Emulsion-type water-based varnish (manufactured by Toyo Ink Co., Ltd.) • UV High Gloss Varnish: FD Rio Clear EX (manufactured by Toyo Ink Co., Ltd.) The above emulsion-type water-based varnish contains acrylic resin and silicone resin as solid components.

[0028] <Examples 1-4> Using a roll-based method, an ink layer and a varnish layer were sequentially formed on the surface of coated cardboard. The materials used and the thickness of the layers are shown in Table 1.

[0029] <Comparative Examples 1-6> An ink layer and a varnish layer were sequentially formed on the surface of coated cardboard using either a roll method or a chamber method. The materials used and the thickness of the layers are shown in Table 2. In Comparative Examples 4 to 6, the ink layer was cured by irradiating it with UV light after its formation. In Comparative Example 4, the ink layer was cured by irradiating the varnish layer with UV light after its formation. In Comparative Example 6, after the formation of the varnish layer, the varnish layer was subjected to hot pressing under the following conditions. ·Temperature: 125℃ • Pressure: 25 MPa • Time: 0.2 seconds

[0030] <Rating> The following evaluations were performed on the printed materials related to the examples and comparative examples. (1) Measurement of gloss The gloss level was measured at a 60-degree incident angle using a gloss meter manufactured by Horiba, Ltd. (product name: Handy Gloss Meter). The measurement was repeated 10 times, and the upper and lower limits are recorded in Tables 1 and 2.

[0031] (2) Evaluation of abrasion resistance The abrasion resistance of the varnish layer was evaluated in accordance with the method described in JIS K5701-1. The varnish layer was visually observed at 10, 50, 100, 300, and 500 friction cycles, and its abrasion resistance was evaluated according to the following criteria. The results are shown in Tables 1 and 2. ○: No wear or tear on the varnish layer is observed. △: Although wear is observed in the varnish layer, the ink layer is not exposed. ×: The varnish layer has worn away, exposing the ink layer.

[0032] (3) coefficient of friction The static and dynamic friction coefficients of the varnish layer surface were measured using a JSPS-type friction tester (manufactured by Tester Industries Co., Ltd.). The results are shown in Tables 1 and 2.

[0033] [Table 1]

[0034] [Table 2] [Explanation of Symbols]

[0035] 1...Printed material, 1a...Surface, 3,13...Oil-based ink layer, 13a...Layer, 13b...Surface, 5,15...Aqueous varnish layer, 5a,15a...Surface, 10,20...Printed material.

Claims

1. A substrate having a surface to which printing is applied, An oil-based ink layer provided on the aforementioned surface, A water-based varnish layer is provided so as to cover the oil-based ink layer, Equipped with, The aforementioned aqueous varnish layer contains a dried emulsion-type aqueous varnish comprising an acrylic resin and a silicone resin as resin components, and is formed to be thicker than the aforementioned oil-based ink layer. A printed material in which the ratio of the thickness T5 of the aqueous varnish layer to the thickness T3 of the oil-based ink layer (T5 / T3) is 3 / 2 or more and 7 / 2 or less.

2. The printed material according to claim 1, wherein the thickness of the aqueous varnish layer is 2.5 μm or more.

3. The printed material according to claim 1 or 2, wherein the thickness of the oil-based ink layer is 1.5 μm or less.

4. A step of forming a coating film of an emulsion-type water-based varnish containing acrylic resin and silicone resin as resin components on the surface of an oil-based ink layer, The process involves drying the aforementioned coating film to form an aqueous varnish layer containing the dried aqueous varnish on the surface of the oil-based ink layer, Includes, A method for manufacturing printed materials, comprising forming the coating film such that the aqueous varnish layer is thicker than the oil-based ink layer, and the ratio of the thickness T5 of the aqueous varnish layer to the thickness T3 of the oil-based ink layer (T5 / T3) is 3 / 2 or more and 7 / 2 or less.

5. The method for manufacturing a printed article according to claim 4, further comprising the step of heating and pressurizing the surface of the aqueous varnish layer.

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