Coating pearl paper and method for producing the same

Abstract

To provide coating pearl paper and a method for producing the same.SOLUTION: The coating pearl paper includes pearl paper and a coating layer. THe pearl paper includes a main layer and two sub-layers on both sides of the main layer. The main layer contains a first resin and a plurality of first mixed inorganic particles. Each of the sub-layers contains a second resin and a plurality of second mixed inorganic particles. A coating liquid for forming the coating layer contains a third resin, a plurality of third mixed inorganic particles and water. The third resin is a polyurethane resin graft-altered by acylate. With the total weight of the coating liquid set to 100 wt%, a content of the third resin is 18.5 wt% to 21.5 wt%, a content of the third mixed inorganic particles is 4 wt% to 8 wt%, and a content of the water is 71.8 wt% to 76.8 wt%.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to pearl paper and a manufacturing method thereof, and more particularly to coated pearl paper and a manufacturing method thereof. [Background technology]

[0002] In the conventional technology, in order to print ink on pearl paper, a coating layer is first applied to the pearl paper, but the coating layer has poor compatibility with the ink and the pearl paper, making it difficult for the ink to adhere to the coating layer. Summary of the Invention [Problem to be solved by the invention]

[0003] The technical problem that the present invention aims to solve is to provide a coated pearl paper and a manufacturing method thereof, which overcomes the shortcomings of the prior art, that is, the problem that ink is difficult to adhere to the coating layer of conventional pearl paper. [Means for solving the problem]

[0004] In order to solve the above technical problems, one technical means adopted by the present invention is a coated pearl paper comprising pearl paper and a coating layer. The pearl paper comprises a main layer and two sub-layers on both sides of the main layer, the main layer comprises a first resin comprising polypropylene and a plurality of first mixed inorganic particles comprising calcium carbonate, silicon dioxide and titanium dioxide, each of the sub-layers comprises a second resin comprising polypropylene and a plurality of second mixed inorganic particles comprising calcium carbonate, silicon dioxide and titanium dioxide, and the coating layer is formed by applying a coating liquid to the front of one of the pearl papers. The coating liquid is formed by applying it to the sublayer, and the coating liquid contains a third resin which is a polyurethane resin graft-modified with acrylate, a plurality of third mixed inorganic particles containing calcium carbonate, silicon dioxide and titanium dioxide, and water, and the total weight of the coating liquid is 100 wt%, and the content of the third resin is 18.5 wt% to 21.5 wt%, the content of the third mixed inorganic particles is 4 wt% to 8 wt%, and the content of the water is 71.8 wt% to 76.8 wt%.

[0005] Preferably, the third resin is graft-modified using monomers consisting of (a) 90 to 95 wt % of an alkyl-containing (meth)acrylate, (b) 4 to 9 wt % of a hydroxyl group-containing (meth)acrylate, and (c) 1 to 5 wt % of a carboxyl group-containing vinyl monomer, with the total of components (a) to (c) being 100 wt %.

[0006] Preferably, in the third mixed inorganic particles, the calcium carbonate content is 0.5 wt% to 7 wt%, the silicon dioxide content is 0.5 wt% to 6 wt%, and the titanium dioxide content is 0.5 wt% to 2 wt%, with the total weight of the coating liquid being 100 wt%.

[0007] Preferably, the coating liquid further contains at least one additive selected from the group consisting of an auxiliary, a catalyst, and a co-solvent, and the content of the additive is 0.5 wt% to 1 wt% based on the total weight of the coating liquid being 100 wt%.

[0008] Preferably, when the total weight of the main layer is 100 wt%, the content of the first resin is 85 wt% to 95 wt%, the content of the first mixed inorganic particles is 5 wt% to 15 wt%, when the total weight of the sublayers is 100 wt%, the content of the second resin is 85 wt% to 95 wt%, and the content of the second mixed inorganic particles is 5 wt% to 15 wt%, and in the main layer, the content of calcium carbonate or the content of silicon dioxide is higher than the content of titanium dioxide, and in each of the sublayers, the content of titanium dioxide is higher than the content of silicon dioxide.

[0009] Preferably, the light transmittance of the coated pearl paper is 20.5% to 20.8%, and the haze value of the coated pearl paper is 98.1% to 98.8%.

[0010] In order to solve the above technical problems, another technical means adopted by the present invention provides a method for producing coated pearl paper, which includes a pearl paper forming step of forming a pearl paper having a main layer and two sub-layers on both sides of the main layer from polypropylene, calcium carbonate, silicon dioxide, and titanium dioxide by co-extrusion with an extruder, and a coating step of coating the pearl paper with a coating liquid to form a coating layer on one sub-layer of the pearl paper to form a coated pearl paper, wherein the main layer includes a first resin including polypropylene and a plurality of first mixed inorganic particles including calcium carbonate, silicon dioxide, and titanium dioxide, and the coating liquid is applied to the pearl paper to form a coating layer on one sub-layer of the pearl paper, and the coating liquid is applied to the pearl paper to form a coating layer on one sub-layer of the pearl paper, and the coating liquid is applied to the pearl paper to form a coating layer on the main layer. Each of the sublayers includes a second resin including polypropylene and a plurality of second mixed inorganic particles including calcium carbonate, silicon dioxide and titanium dioxide, and the coating liquid includes a third resin which is a polyurethane resin graft-modified with acrylate, a plurality of third mixed inorganic particles including calcium carbonate, silicon dioxide and titanium dioxide, and water, and the content of the third resin is 18.5 wt% to 21.5 wt%, the content of the third mixed inorganic particles is 4 wt% to 8 wt%, and the content of the water is 71.8 wt% to 76.8 wt%, assuming a total weight of the coating liquid to be 100 wt%.

[0011] Preferably, the third resin is graft-modified using monomers consisting of (a) 90 to 95 wt % of an alkyl-containing (meth)acrylate, (b) 4 to 9 wt % of a hydroxyl group-containing (meth)acrylate, and (c) 1 to 5 wt % of a carboxyl group-containing vinyl monomer, with the total of components (a) to (c) being 100 wt %.

[0012] Preferably, in the third mixed inorganic particles, the calcium carbonate content is 0.5 wt% to 7 wt%, the silicon dioxide content is 0.5 wt% to 6 wt%, and the titanium dioxide content is 0.5 wt% to 2 wt%, with the total weight of the coating liquid being 100 wt%.

[0013] Preferably, the coating liquid further contains at least one additive selected from the group consisting of an auxiliary, a catalyst, and a co-solvent, and the content of the additive is 0.5 wt% to 1 wt% based on the total weight of the coating liquid being 100 wt%.

[0014] Preferably, when the total weight of the main layer is 100 wt%, the content of the first resin is 85 wt% to 95 wt%, the content of the first mixed inorganic particles is 5 wt% to 15 wt%, when the total weight of the sublayers is 100 wt%, the content of the second resin is 85 wt% to 95 wt%, and the content of the second mixed inorganic particles is 5 wt% to 15 wt%, and in the main layer, the content of calcium carbonate or the content of silicon dioxide is higher than the content of titanium dioxide, and in each of the sublayers, the content of titanium dioxide is higher than the content of silicon dioxide.

[0015] Preferably, the light transmittance of the coated pearl paper is 20.5% to 20.8%, and the haze value of the coated pearl paper is 98.1% to 98.8%. Effect of the Invention

[0016] As an advantageous effect of the present invention, the coated pearl paper and its manufacturing method according to the present invention have the following technical features: "The coating liquid contains a third resin, which is a polyurethane resin graft-modified with acrylate, a plurality of third mixed inorganic particles containing calcium carbonate, silicon dioxide and titanium dioxide, and water" and "When the total weight of the coating liquid is 100 wt%, the content of the third resin is 18.5 wt% to 21.5 wt%, the content of the third mixed inorganic particles is 4 wt% to 8 wt%, and the content of water is 71.8 wt% to 76.8 wt%". These effectively improve the problem that ink is difficult to adhere to the coating layer of conventional pearl paper. [Brief description of the drawings]

[0017] [Figure 1]FIG. 1 is a schematic diagram of a coated pearl paper according to an embodiment of the present invention. [Diagram 2] 1 is a flowchart of a method for producing coated pearl paper according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] In order to better understand the features and technical contents of the present invention, please refer to the following detailed description of the present invention and the accompanying drawings, which are provided for reference and explanation only and are not intended to limit the scope of the present invention.

[0019] Hereinafter, the embodiments of the "coated pearl paper and its manufacturing method" according to the present invention will be described in detail with reference to certain specific embodiments, and those skilled in the art will be able to understand the advantages and effects of the present invention based on the contents disclosed in this specification. The present invention can be implemented or applied in other different specific embodiments, and various modifications and changes can be made to each detail in this specification based on different perspectives and applications without departing from the concept of the present invention. In addition, as described in advance, the accompanying drawings of the present invention are simple schematic illustrations and are not drawn based on actual size. The technical contents of the present invention will be described in more detail based on the following embodiments, but the disclosed contents do not limit the scope of protection of the present invention.

[0020] It should be understood that, although the present specification may use the terms "first", "second", "third" and the like to describe various elements or signals, these elements or signals are not limited by these terms. These terms are mainly used to distinguish one element from another element or one signal from another signal. In addition, the term "or" used in the present specification may include any one or more combinations of the associated listed items according to actual circumstances.

[0021] [Coated pearl paper] Fig. 1 is a schematic diagram of a coated pearl paper according to an embodiment of the present invention. As shown in Fig. 1, in an embodiment of the present invention, a coated pearl paper 100 is provided. The coated pearl paper includes a pearl paper 1 and a coating layer 2. Ink can easily adhere to the coating layer 2 of the coated pearl paper 100 and will not peel off from the coating layer 2.

[0022] The pearl paper 1 includes a main layer 11 and two sublayers 12 on either side of the main layer 11. The main layer 11 includes a first resin including polypropylene and a plurality of first mixed inorganic particles including calcium carbonate, silicon dioxide, and titanium dioxide. Each of the sublayers 12 includes a second resin including polypropylene and a plurality of second mixed inorganic particles including calcium carbonate, silicon dioxide, and titanium dioxide.

[0023] The content of the first resin is 85 wt% to 95 wt% and the content of the first mixed inorganic particles is 5 wt% to 15 wt% relative to the total weight of the main layer 11. The content of the second resin is 85 wt% to 95 wt% and the content of the second mixed inorganic particles is 5 wt% to 15 wt% relative to the total weight of the sublayer 12.

[0024] The resin component of the main layer 11 and the sublayers 12 may consist only of polypropylene. The number average molecular weight of the polypropylene in the main layer 11 may be 100,000 to 200,000, and the number average molecular weight of the polypropylene in each of the sublayers 12 may be 100,000 to 200,000.

[0025] Preferably, the content of calcium carbonate or silicon dioxide in the main layer 11 can be higher than the content of titanium dioxide. The content of titanium dioxide in each of the sublayers 12 can be higher than the content of silicon dioxide. The combination of a relatively high content of calcium carbonate or silicon dioxide and a relatively low content of titanium dioxide in the main layer 11 reduces the cost of the coated pearlescent paper 100. The thickness of each of the sublayers 12 is thinner than the thickness of the main layer 11, and the coating pearlescent paper 100 exhibits a white color by adding a relatively high content of titanium dioxide to each of the sublayers 12.

[0026] Specifically, in the main layer 11, the total weight of the first mixed inorganic particles is taken as 100 wt%, and the content of calcium carbonate is 50 wt% to 80 wt%, the content of silicon dioxide is 10 wt% to 20 wt%, and the content of titanium dioxide is 1 wt% to 10 wt%. In the sublayer 12, the total weight of the second mixed inorganic particles is taken as 100 wt%, and the content of calcium carbonate is 50 wt% to 80 wt%, the content of silicon dioxide is 1 wt% to 10 wt%, and the content of titanium dioxide is 10 wt% to 20 wt%. The thickness of the main layer 11 is 20 μm to 40 μm, and the thickness of the sublayer 12 is 5 μm to 15 μm.

[0027] The coating layer 2 is formed by applying a coating liquid to one of the sublayers 12 of the pearl paper 1. The coating layer 2 may have a thickness of 2 μm to 3 μm.

[0028] The coating liquid contains a third resin, a plurality of third mixed inorganic particles, and water. The third resin is a polyurethane resin graft-modified with an acrylate, and the third mixed inorganic particles contain calcium carbonate, silicon dioxide, and titanium dioxide. When the total weight of the coating liquid is 100 wt%, the content of the third resin is 18.5 wt% to 21.5 wt%, the content of the third mixed inorganic particles is 4 wt% to 8 wt%, and the content of water is 71.8 wt% to 76.8 wt%. In other words, in the coating layer 2, the value of the ratio of the content of the third resin to the content of the third mixed inorganic particles (third resin / third mixed inorganic particles) is about 2.3 to 5.4 (i.e., (18.5 / 8) to (21.5 / 4)). The third resin has excellent compatibility with the pearl paper, and also has excellent compatibility with the ink printed on the coating layer, so that the coating layer 2 is not easily peeled off from the pearl paper 1, and the ink printed on the coating layer 2 is not easily peeled off from the coating layer 2. The third mixed inorganic particles can also adsorb the pigment in the ink, improving the print quality of the ink.

[0029] The third resin is graft-modified using monomers consisting of (a) 90-95 wt% alkyl-containing (meth)acrylate, (b) 4-9 wt% hydroxyl-containing (meth)acrylate, and (c) 1-5 wt% carboxyl-containing vinyl monomer, where the total of components (a) to (c) is 100 wt%. The alkyl-containing (meth)acrylate may be selected from at least one of the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, methoxyethyl (meth)acrylate, and ethoxymethyl (meth)acrylate. The hydroxyl group-containing (meth)acrylate may be selected from at least one of the group consisting of 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, chloro 2-hydroxypropyl acrylate, diethylene glycol mono(meth)acrylate, and allyl alcohol. The carboxyl group-containing vinyl monomer may be selected from at least one of the group consisting of acrylic acid, methacrylic acid, itaconic acid, butenoic acid, maleic acid, fumaric acid, and maleic anhydride. The number average molecular weight of the polyurethane resin may be 5,000 to 30,000.

[0030] In the third mixed inorganic particles, the calcium carbonate content is 0.5 wt% to 7 wt%, the silicon dioxide content is 0.5 wt% to 6 wt%, and the titanium dioxide content is 0.5 wt% to 2 wt%, relative to the total weight of the coating liquid being 100 wt%.

[0031] The coating liquid may further contain at least one additive selected from the group consisting of an auxiliary, a catalyst, and a co-solvent, and the content of the additive is 0.5 wt% to 1 wt% based on the total weight of the coating liquid being 100 wt%.

[0032] The auxiliary may adjust the surface tension of the coating liquid, and can improve the flatness of the coating layer 2 and the wettability with the pearl paper. The catalyst can control the rate of the crosslinking reaction of the coating liquid. The co-solvent can control the volatilization rate of the liquid components in the coating liquid.

[0033] The auxiliary may be a silicon-containing additive, a fluorine-containing additive, or a silicon- and fluorine-containing additive. The silicon-containing additive may be BYK307, BYK325, BYK331, BYK380N, or BYK381 manufactured by BYK. The fluorine-containing additive may be FC-4430, FC-4432 manufactured by 3M, Zonyl FSN-100 manufactured by DuPont, or DSX manufactured by Daikin Japan. The silicon- and fluorine-containing additive may be BYK346, BYK347, or BYK348 manufactured by BYK.

[0034] The catalyst may be a metal salt, an inorganic substance, a salt, an organic substance, an alkaline substance, or an acidic substance. The co-solvent may be at least one selected from the group consisting of solvents such as methanol, ethanol, n-propanol, isopropanol, dimethylsulfoxide, acetone, and tetrahydrofuran.

[0035] The coated pearl paper 100 has a light transmittance of 20.5% to 20.8% and a haze value of 98.1% to 98.8%.

[0036] [Manufacturing method of coated pearl paper] As shown in Fig. 2, which is a flow chart of the method for manufacturing coated pearl paper according to an embodiment of the present invention, a method for manufacturing coated pearl paper is provided in an embodiment of the present invention. The coated pearl paper 100 can be manufactured by the method for manufacturing coated pearl paper, but the present invention is not limited thereto. The method for manufacturing coated pearl paper includes a pearl paper forming step S110 and a coating step S120.

[0037] In the pearl paper forming step S110, a pearl paper 1 having a main layer 11 and two sublayers 12 on both sides of the main layer 11 is formed from polypropylene, calcium carbonate, silicon dioxide, and titanium dioxide by co-extrusion using an extruder. The main layer 11 includes a first resin including polypropylene and a plurality of first mixed inorganic particles including calcium carbonate, silicon dioxide, and titanium dioxide. Each of the sublayers 12 includes a second resin including polypropylene and a plurality of second mixed inorganic particles including calcium carbonate, silicon dioxide, and titanium dioxide.

[0038] When the total weight of the main layer 11 is 100 wt%, the content of the first resin is 85 wt% to 95 wt%, and the content of the first mixed inorganic particles is 5 wt% to 15 wt%, when the total weight of the sublayers 12 is 100 wt%, the content of the second resin is 85 wt% to 95 wt%, and the content of the second mixed inorganic particles is 5 wt% to 15 wt%, and in the main layer 11, the content of calcium carbonate or the content of silicon dioxide is higher than the content of titanium dioxide, and in each of the sublayers 12, the content of titanium dioxide is higher than the content of silicon dioxide.

[0039] In the coating step S120, a coating liquid is applied to the pearl paper 1 so as to form a coating layer 2 on one of the sublayers 12 of the pearl paper 1, thereby forming a coated pearl paper 100. The coating liquid contains a third resin, a plurality of third mixed inorganic particles, and water. The third resin is a polyurethane resin graft-modified with an acrylate, and the third mixed inorganic particles contain calcium carbonate, silicon dioxide, and titanium dioxide. When the total weight of the coating liquid is 100 wt%, the content of the third resin is 18.5 wt% to 21.5 wt%, the content of the third mixed inorganic particles is 4 wt% to 8 wt%, and the content of water is 71.8 wt% to 76.8 wt%.

[0040] The manufacturing method of the coated pearl paper may further include a biaxial stretching step before the coating step S120 and after the pearl paper forming step S110. In the biaxial stretching step, the pearl paper having a three-layer structure is biaxially stretched. The biaxial stretching method may be, for example, a longitudinal uniaxial stretching method, a transverse uniaxial stretching method, a longitudinal sequential biaxial stretching method, or a longitudinal simultaneous biaxial stretching method, but the present invention is not limited thereto. In addition, the biaxial stretching method may be, for example, a stretching temperature of 50°C to 150°C, in which the unstretched pearl paper is preheated and stretched along the width direction (also called the transverse direction, TD) of the unstretched pearl paper based on different stretch ratios, and further stretched along the length direction (also called the machine direction, MD) of the pearl paper.

[0041] The third resin is graft-modified using monomers consisting of (a) 90 to 95 wt % of an alkyl-containing (meth)acrylate, (b) 4 to 9 wt % of a hydroxyl group-containing (meth)acrylate, and (c) 1 to 5 wt % of a carboxyl group-containing vinyl monomer, with the total of components (a) to (c) being 100 wt %.

[0042] In the third mixed inorganic particles, the calcium carbonate content is 0.5 wt% to 7 wt%, the silicon dioxide content is 0.5 wt% to 6 wt%, and the titanium dioxide content is 0.5 wt% to 2 wt%, relative to the total weight of the coating liquid being 100 wt%.

[0043] The coating liquid may further contain at least one additive selected from the group consisting of an auxiliary, a catalyst, and a co-solvent, and the content of the additive is 0.5 wt% to 1 wt% based on the total weight of the coating liquid being 100 wt%.

[0044] The coated pearl paper 100 has a light transmittance of 20.5% to 20.8% and a haze value of 98.1% to 98.8%. EXAMPLES

[0045] [Measurement of experimental data] The present invention will be described in detail below with reference to Examples 1 to 5 and Comparative Examples 1 to 3. However, these Examples are provided for the purpose of understanding the present invention, and the present invention is not limited thereto.

[0046] In Examples 1 to 5 and Comparative Examples 1 to 3, different coating solutions were applied to the same pearl paper, and the main layer of the pearl paper contained 70 wt% polypropylene, 21 wt% calcium carbonate, 6 wt% silicon dioxide, and 3 wt% titanium dioxide. Each of the sublayers of the pearl paper contained 70 wt% polypropylene, 21 wt% calcium carbonate, 3 wt% silicon dioxide, and 6 wt% titanium dioxide.

[0047] [Example 1] The coating solution contained 18.5 wt% of acrylate-grafted polyurethane resin, 4 wt% of the third mixed inorganic particles, 76.8 wt% of water, and 0.7 wt% of additives. The thickness of the coating layer was 2.2 μm. The third mixed inorganic particles contained 3.4 wt% of calcium carbonate, 0.5 wt% of silicon dioxide, and 0.1 wt% of titanium dioxide.

[0048] [Example 2] The coating solution contained 18.5 wt% of acrylate-grafted polyurethane resin, 6 wt% of the third mixed inorganic particles, 74.8 wt% of water, and 0.7 wt% of additives. The thickness of the coating layer was 2.5 μm. The third mixed inorganic particles contained 5.4 wt% of calcium carbonate, 0.5 wt% of silicon dioxide, and 0.1 wt% of titanium dioxide.

[0049] [Example 3] The coating solution contained 18.5 wt% of acrylate-grafted polyurethane resin, 8 wt% of the third mixed inorganic particles, 72.8 wt% of water, and 0.7 wt% of additives. The thickness of the coating layer was 2.5 μm. The third mixed inorganic particles contained 7.4 wt% of calcium carbonate, 0.5 wt% of silicon dioxide, and 0.1 wt% of titanium dioxide.

[0050] [Example 4] The coating solution contained 20 wt% of polyurethane resin grafted with acrylate, 6 wt% of the third mixed inorganic particles, 73.3 wt% of water, and 0.7 wt% of additives. The thickness of the coating layer was 2.8 μm. The third mixed inorganic particles contained 5.4 wt% of calcium carbonate, 0.5 wt% of silicon dioxide, and 0.1 wt% of titanium dioxide.

[0051] [Example 5] The coating solution contained 21.5 wt% of acrylate-grafted polyurethane resin, 6 wt% of the third mixed inorganic particles, 71.8 wt% of water, and 0.7 wt% of additives. The thickness of the coating layer was 3 μm. The third mixed inorganic particles contained 5.4 wt% of calcium carbonate, 0.5 wt% of silicon dioxide, and 0.1 wt% of titanium dioxide.

[0052] [Comparative Example 1] The coating solution contained 24.5 wt% of polyurethane resin grafted with acrylate, 0.05 wt% of the third mixed inorganic particles, 74.8 wt% of water, and 0.7 wt% of additives. The thickness of the coating layer was 3 μm. The third mixed inorganic particles contained 0.030 wt% of calcium carbonate, 0.015 wt% of silicon dioxide, and 0.005 wt% of titanium dioxide.

[0053] [Comparative Example 2] The coating solution contained 14.8 wt% of acrylate-grafted polyurethane resin, 4.8 wt% of the third mixed inorganic particles, 79.7 wt% of water, and 0.7 wt% of additives. The thickness of the coating layer was 0.8 μm. The third mixed inorganic particles contained 4.2 wt% of calcium carbonate, 0.5 wt% of silicon dioxide, and 0.1 wt% of titanium dioxide.

[0054] [Comparative Example 3] The coating solution contained 6.5 wt% of acrylate-grafted polyurethane resin, 18 wt% of the third mixed inorganic particles, 74.8 wt% of water, and 0.7 wt% of additives. The thickness of the coating layer was 3 μm. The third mixed inorganic particles contained 15.0 wt% of calcium carbonate, 2.5 wt% of silicon dioxide, and 0.5 wt% of titanium dioxide.

[0055] The component composition, thickness, light transmittance, haze value, glossiness, adhesion, and print quality of the coating layer in Examples 1 to 5 and Comparative Examples 1 to 3 are shown in Table 1. The measurement methods are described below.

[0056] The light transmittance was measured using a haze meter TC-H III DPK according to the ISO 14782 standard.

[0057] The haze value was measured using a haze meter TC-H III DPK in accordance with the ISO 14782 standard.

[0058] Gloss measurement: performed using a gloss meter ZGM1110.268 according to the standard ASTM D2457.

[0059] The adhesion was measured by a cross-hatch test using 3M tape in accordance with ASTM D3359.

[0060] Print quality was measured by observing print appearance and image resolution.

[0061] The print reliability was measured by a cross-hatch test using 3M tape according to ASTM D3359.

[0062] The surface roughness of the coating layer was measured using a 3D laser microscope based on the JIS B 0601-2001 standard.

[0063] [Table 1]

[0064] [Consideration of measurement results] In Examples 1 to 5, by setting the content of the third resin to 18.5 wt% to 21.5 wt%, the content of the third mixed inorganic particles to 4 wt% to 8 wt%, the content of the water to 71.8 wt% to 76.8 wt%, and the thickness of the coating layer to 2.2 μm to 3 μm, the coated pearl paper had a light transmittance of 20.5% to 20.8%, a haze value of 98.1% to 98.7%, a gloss level of 5.1 GU to 5.9 GU, excellent adhesion, print quality, and print reliability, and the surface roughness (Ra) of the coating layer was 0.55 μm to 0.728 μm.

[0065] In Comparative Example 1, the content of the third mixed inorganic particles was low, so the gloss of the coated pearl paper was high, the absorbency of the UV ink was poor, and the print quality was NG. In Comparative Example 2, the thickness of the coating layer was thin, so the print quality of the coated pearl paper was NG, and the print reliability of the UV ink was NG. In Comparative Example 3, the content of the third mixed inorganic particles was high, which led to peeling of the coating layer, and the print reliability of the coating layer, pearl paper, and UV ink was NG.

[0066] [Advantageous Effects of the Embodiments] As an advantageous effect of the present invention, the coated pearl paper and its manufacturing method according to the present invention have the following technical features: "The coating liquid contains a third resin, which is a polyurethane resin graft-modified with acrylate, a plurality of third mixed inorganic particles containing calcium carbonate, silicon dioxide and titanium dioxide, and water" and "When the total weight of the coating liquid is 100 wt%, the content of the third resin is 18.5 wt% to 21.5 wt%, the content of the third mixed inorganic particles is 4 wt% to 8 wt%, and the content of water is 71.8 wt% to 76.8 wt%". These effectively improve the problem that ink is difficult to adhere to the coating layer of conventional pearl paper.

[0067] The above disclosure is merely a preferred embodiment of the present invention, and the scope of the claims of the present invention is not limited thereto. Therefore, all equivalent technical modifications made by utilizing the specification and drawings of the present invention are included in the scope of the claims of the present invention. [Explanation of symbols]

[0068] 100 ···Coated pearl paper 1. Pearl paper 11. Main Layer 12 Sublayers 2. Coating layer S110 Pearl paper forming process S120: Coating process

Claims

1. A coated pearl paper comprising pearl paper and a coating layer, The pearl paper comprises a main layer and two sub-layers on either side of the main layer, the main layer comprising a first resin including polypropylene and a plurality of first mixed inorganic particles including calcium carbonate, silicon dioxide and titanium dioxide, each of the sub-layers comprising a second resin including polypropylene and a plurality of second mixed inorganic particles including calcium carbonate, silicon dioxide and titanium dioxide; The coating layer is formed by applying a coating liquid to one of the sub-layers of the pearl paper; The coating liquid includes a third resin, which is a polyurethane resin graft-modified with an acrylate, a plurality of third mixed inorganic particles including calcium carbonate, silicon dioxide, and titanium dioxide, and water; A coated pearl paper, characterized in that, when the total weight of the coating liquid is 100 wt%, the content of the third resin is 18.5 wt% to 21.5 wt%, the content of the third mixed inorganic particles is 4 wt% to 8 wt%, and the content of water is 71.8 wt% to 76.8 wt%.

2. The coated pearl paper according to claim 1, wherein the third resin is graft-modified using monomers consisting of (a) 90 to 95 wt % of an alkyl-containing (meth)acrylate, (b) 4 to 9 wt % of a hydroxyl group-containing (meth)acrylate, and (c) 1 to 5 wt % of a carboxyl group-containing vinyl monomer, with the total of components (a) to (c) being 100 wt %.

3. 2. The coated pearl paper according to claim 1, wherein in the third mixed inorganic particles, the calcium carbonate content is 0.5 wt % to 7 wt %, the silicon dioxide content is 0.5 wt % to 6 wt %, and the titanium dioxide content is 0.5 wt % to 2 wt %, with the total weight of the coating liquid being 100 wt %.

4. The coated pearl paper according to claim 1, wherein the coating liquid further contains at least one additive selected from the group consisting of an auxiliary, a catalyst, and a co-solvent, and the content of the additive is 0.5 wt % to 1 wt % based on the total weight of the coating liquid being 100 wt %.

5. The content of the first resin is 85 wt % to 95 wt % and the content of the first mixed inorganic particles is 5 wt % to 15 wt % with respect to a total weight of the main layer being 100 wt %; The content of the second resin is 85 wt % to 95 wt % and the content of the second mixed inorganic particles is 5 wt % to 15 wt % of the total weight of the sublayer, 2. The coated pearl paper according to claim 1, wherein in the main layer, the calcium carbonate content or the silicon dioxide content is higher than the titanium dioxide content, and in each of the sublayers, the titanium dioxide content is higher than the silicon dioxide content.

6. 2. The coated pearl paper according to claim 1, wherein the light transmittance of the coated pearl paper is 20.5% to 20.8%, and the haze value of the coated pearl paper is 98.1% to 98.8%.

7. a pearl paper forming step of co-extruding polypropylene, calcium carbonate, silicon dioxide, and titanium dioxide through an extruder to form a pearl paper having a main layer and two sub-layers on both sides of the main layer; A coating step of coating the pearl paper with a coating liquid to form a coating layer on one of the sub-layers of the pearl paper to form a coated pearl paper; The main layer includes a first resin including polypropylene and a plurality of first mixed inorganic particles including calcium carbonate, silicon dioxide, and titanium dioxide, and each of the sublayers includes a second resin including polypropylene and a plurality of second mixed inorganic particles including calcium carbonate, silicon dioxide, and titanium dioxide; The coating liquid includes a third resin, which is a polyurethane resin graft-modified with an acrylate, a plurality of third mixed inorganic particles including calcium carbonate, silicon dioxide, and titanium dioxide, and water; A method for producing coated pearl paper, characterized in that, when the total weight of the coating liquid is 100 wt%, the content of the third resin is 18.5 wt% to 21.5 wt%, the content of the third mixed inorganic particles is 4 wt% to 8 wt%, and the content of water is 71.8 wt% to 76.8 wt%.

8. The method for producing coated pearl paper according to claim 7, wherein the third resin is graft-modified using monomers consisting of (a) 90 to 95 wt % of an alkyl-containing (meth)acrylate, (b) 4 to 9 wt % of a hydroxyl group-containing (meth)acrylate, and (c) 1 to 5 wt % of a carboxyl group-containing vinyl monomer, with the total of components (a) to (c) being 100 wt %.

9. The method for producing coated pearl paper according to claim 7, wherein in the third mixed inorganic particles, the calcium carbonate content is 0.5 wt% to 7 wt%, the silicon dioxide content is 0.5 wt% to 6 wt%, and the titanium dioxide content is 0.5 wt% to 2 wt%, with the total weight of the coating liquid being 100 wt%.

10. The method for producing coated pearl paper according to claim 7, wherein the coating liquid further contains at least one additive selected from the group consisting of an auxiliary, a catalyst, and a co-solvent, and the content of the additive is 0.5 wt% to 1 wt% based on the total weight of the coating liquid being 100 wt%.

11. 8. The method for producing coated pearl paper according to claim 7, wherein, when a total weight of the main layer is 100 wt%, the content of the first resin is 85 wt% to 95 wt%, the content of the first mixed inorganic particles is 5 wt% to 15 wt%, and when a total weight of the sub-layers is 100 wt%, the content of the second resin is 85 wt% to 95 wt%, and the content of the second mixed inorganic particles is 5 wt% to 15 wt%, and in the main layer, the content of calcium carbonate or the content of silicon dioxide is higher than the content of titanium dioxide, and in each of the sub-layers, the content of titanium dioxide is higher than the content of silicon dioxide.

12. The method for producing coated pearl paper according to claim 7, wherein the light transmittance of the coated pearl paper is 20.5% to 20.8%, and the haze value of the coated pearl paper is 98.1% to 98.8%.

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