Printed paper material and method for producing printed paper material

Abstract

To prevent peeling of ink.SOLUTION: A packaging material 1 forming a packaging bag comprises coated paper 2, an anchor coat layer 4 laminated on the coated surface of the coated paper 2, a color ink layer 5 laminated on a surface of the anchor coat layer 4, an overprint layer 6 laminated on a surface of the ink layer 5, and a heat seal layer 3 laminated on a back surface of the coated paper 2. The anchor coat layer 4 is prepared by mixing an urethane resin and a nitrocellulose resin, whereby improvement in flexibility of the packaging material 1 is achieved by the urethane resin and improvement in heat resistance of the packaging material 1 is achieved by the nitrocellulose resin, respectively.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a paper print and a method for manufacturing a paper print. [Background technology]

[0002] In paper printing, coated paper is sometimes used for its high smoothness, high gloss, and dimensional stability. The coated surface of coated paper allows color printing to develop well, but if the printed surface is bent too much, the ink may peel off (color loss, discoloration). When ink peeling occurs, the base color of the paper (generally white) becomes visible. This phenomenon does not occur with plastic film printing. Because ink peeling results in a poor appearance, it is an obstacle to promoting the use of paper by companies and others who are trying to adopt paper-printed packaging materials in place of packaging materials made with plastic film prints.

[0003] Patent Document 1 describes a coated paper having a barrier coating layer on the coated surface to provide gas barrier properties against oxygen gas, etc. However, Patent Document 1 does not give any consideration to reducing ink peeling. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-77780 Summary of the Invention [Problem to be solved by the invention]

[0005] The purpose of this invention is to reduce ink peeling (color loss, discoloration) when printed coated paper is bent.

[0006] The paper print according to this invention comprises coated paper, an anchor coat layer laminated on the coated surface of the coated paper, the anchor coat layer containing urethane resin and soluble nitrocellulose resin, the urethane resin content exceeding the soluble nitrocellulose resin content, and an ink layer laminated on the surface of the anchor coat layer.

[0007] The present invention also provides a method for manufacturing a paper print, which is characterized by laminating an anchor coat layer containing urethane resin and soluble nitrocellulose resin on the coated surface of coated paper, the anchor coat layer containing urethane resin and soluble nitrocellulose resin, the urethane resin content exceeding the soluble nitrocellulose resin content, and laminating an ink layer on the surface of the anchor coat layer.

[0008] According to this invention, an ink layer is laminated (printed) not on the coated surface of coated paper, but on an anchor coat layer laminated on the coated surface. The anchor coat layer contains urethane resin and soluble nitrocellulose resin, with the urethane resin content exceeding the soluble nitrocellulose resin content, and preferably the main component (more than 50 wt%) being urethane resin. The urethane resin contained in the anchor coat layer improves the flexibility of the printed paper. Furthermore, the soluble nitrocellulose resin contained in the anchor coat layer improves the heat resistance of the printed paper.

[0009] In one embodiment, the anchor coat layer has a composition containing 99 to 68 wt% urethane resin and 1 to 32 wt% soluble nitrocellulose resin, the total of which is 100 wt%. If heat resistance is not required for the paper print, soluble nitrocellulose resin is not necessarily required, but generally, even a small amount of soluble nitrocellulose resin is included, thereby improving the heat resistance of the paper print. It goes without saying that inevitable impurities, i.e., impurities that are present in the raw materials of the anchor coat layer or that are unavoidably mixed in during the manufacturing process and that are essentially unnecessary but are tolerated because they are in trace amounts and do not affect the properties of the anchor coat layer, may be included in the anchor coat layer.

[0010] According to this invention, the anchor coat layer contains urethane resin, which improves the flexibility of paper prints, and as a result, even if the paper print is bent (folded or wrinkled), part of the print (ink layer) peels off and fades, preventing the color of the paper material that makes up the coated paper (generally white) from appearing (ink peeling, coating cracking, coating peeling).

[0011] Preferably, the layer thickness of the anchor coat layer is 1 g / m 2 As a result, improvements in flexibility and heat resistance of printed paper products can be reliably achieved.

[0012] In one embodiment, an adhesive layer is laminated on the surface of the coated paper opposite to the surface on which the anchor coat layer is laminated. For example, the side edges of the coated paper can be glued together to form a cylindrical shape, or the top and bottom edges of the cylindrical coated paper can be further glued together to form a bag. For the adhesive layer, for example, a heat-sealing material that becomes adhesive when heat and pressure are applied can be used.

[0013] In another embodiment, an overprint layer is laminated on the surface of the ink layer. The overprint layer protects the ink layer and can prevent or suppress rubbing of the ink layer (pattern). [Brief explanation of the drawings]

[0014] [Figure 1] FIG. [Figure 2] 2 is an enlarged end view of the packaging material taken along line II-II in FIG. 1. [Figure 3] 1 is an enlarged photograph of a packaging material having an anchor coat layer after a kneading resistance test. [Figure 4] 1 is an enlarged photograph of a packaging material without an anchor coat layer after a kneading resistance test. [Example]

[0015] Fig. 1 shows the back of the packaging bag 10. Fig. 2 is an enlarged end view of the packaging material 1 that constitutes the packaging bag 10, taken along line II-II in Fig. 1.

[0016] The packaging bag 10 is a so-called pillow-type packaging body that is made by heat-sealing both side ends of the packaging material 1 to form a cylindrical body, and then further heat-sealing the top and bottom ends of this cylindrical body. The portion formed by heat-sealing both side ends of the packaging material 1 is called the back seal portion 12. The top and bottom ends of the cylindrical body are indicated by the symbols 13 and 14. The back seal portion 12 is formed on the back of the packaging bag 10, approximately in the center in the width direction.

[0017] In the process of manufacturing the packaging bag 10 and the process of sealing the contents, the two side ends of the packaging material 1 are heat-sealed to form a cylindrical body, then the bottom end 14 of the cylindrical body is heat-sealed to close the bottom opening, the contents are placed into the cylindrical body from the top opening, and then the top end 13 of the cylindrical body is heat-sealed to close the top opening. This completes the packaging bag 10 with the contents sealed inside. For example, individually wrapped confectioneries are sealed inside the packaging bag 10.

[0018] Referring to Figure 2, the packaging material 1 constituting the packaging bag 10 comprises coated paper 2, a heat seal layer 3 laminated on the back (inner surface) of the coated paper 2, an anchor coat layer 4 laminated on the front (outer surface) of the coated paper 2, a color ink layer (pattern layer) 5 laminated on the surface of the anchor coat layer 4, and an overprint layer (hereinafter referred to as OP layer) 6 laminated on the surface of the color ink layer 5.

[0019] The coated paper 2 is composed of a paper layer 2A and a white pigment layer 2B coated on one side (surface) of the paper layer 2A, and has a coating weight of 55 to 100 g / m 2 Hereinafter, the surface of the coated paper 2 on which the white pigment layer 2B is laminated will be referred to as the "coated surface."

[0020] The heat seal layer 3 can be made of low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, polypropylene, unstretched polypropylene, ethylene-vinyl acetate copolymer, ionomer resin, etc. Heat seal agents such as ionomer, polyethylene, EVA, elastomer, chlorinated PP, acrylic, polyester, and EVA (water-based) may be applied to the back surface of the coated paper 2. By laminating the heat seal layer 3 on the back surface of the coated paper, it is possible to form the spine seal portion 12 and close the top and bottom ends 13, 14 by heat sealing, as described above. If the packaging material 1 does not need to be formed into a packaging bag 10, the heat seal layer 3 does not necessarily have to be laminated.

[0021] The anchor coat layer 4 is prepared by mixing urethane resin and soluble nitrocellulose resin. The urethane resin improves the flexibility of the packaging material 1, and the soluble nitrocellulose resin improves the heat resistance of the packaging material 1. In order to achieve the effect of improving flexibility and heat resistance, the mixed resin of urethane resin and soluble nitrocellulose resin is applied to the coated surface of the coated paper 2 at a rate of 1 g / m 2 More than this is applied.

[0022] The anchor coat layer 4 has a coating solid component ratio of 99-68 wt% urethane resin and 1-32 wt% nitrocellulose resin (total 100 wt%). The color fading prevention effect described below is achieved by including urethane resin in the anchor coat layer 4, but heat resistance is often required for the packaging material 1, and for this reason, even a small amount of nitrocellulose resin is included in the anchor coat layer 4. It goes without saying that the anchor coat layer 4 may contain unavoidable impurities, i.e., impurities that are present in the raw materials or that are unavoidably mixed in during the manufacturing process and that are essentially unnecessary but are tolerated because they are in small amounts and do not affect the properties of the anchor coat layer 4.

[0023] The color ink layer (pattern layer) 5 is composed of multiple inks of different colors, such as cyan, magenta, yellow, black, white, and other special colors (orange, pink, etc.), and by layering these inks, patterns with various colors are created.

[0024] The OP layer 6 is a transparent resin layer provided on the color ink layer 5. The OP layer 6 protects the surface of the color ink layer 5, and suppresses or prevents the color ink layer 5 from rubbing.

[0025] If gravure printing is used, the heat seal layer 3, anchor coat layer 4, color ink layer 5, and OP layer 6 are laminated (printed) in sequence by preparing a gravure printing unit for each of these multiple layers (a gravure printing unit for each color in the case of color ink layer 5), and conveying the coated paper 2 to each gravure printing unit in sequence. The gravure printing unit is equipped with a cylindrical gravure printing cylinder with many cells (recesses) formed on its surface and a cylindrical pressure roller facing this, and the resin, ink, etc. filled in the cells is transferred to the coated paper 2 sandwiched between the gravure printing cylinder and the pressure roller, thereby laminating (printing) these layers.

[0026] Instead of gravure printing, offset printing, inkjet printing, letterpress printing, screen printing, transfer printing, flexographic printing, and other printing methods may be used.

[0027] As described above, in order to provide the packaging material 1 with flexibility and heat resistance, the anchor coat layer 4 is formed at 1 g / m 2 It is preferable to have a layering amount of 1 g / m or more. 2 In order to laminate the above anchor coat layer 4, the anchor coat layer 4 may be laminated (printed) multiple times onto the coated paper 2, in which case multiple anchor coat layers 4 will be laminated between the coated paper 2 and the color ink layer 5.

[0028] Furthermore, by attaching an electrostatic transfer device including a charging bar, a static electricity removal bar, and a power supply unit to the gravure printing unit for printing the color ink layer 5, the transfer of ink from the gravure printing cylinder (cell) provided in the gravure printing unit to the anchor coat layer 4 can be assisted by electrostatic force (electrostatic printing). This improves the transferability of color ink and improves printing quality.

[0029] Table 1 shows the test results of the "crease peeling resistance test" and the "crush resistance test" for packaging material 1 (Example 1) with the above-mentioned anchor coat layer 4 and packaging material (Comparative Example 1) without the anchor coat layer 4. Conditions other than the presence or absence of the anchor coat layer 4 were the same for Example 1 and Comparative Example 1.

[0030] [Table 1]

[0031] In the "Rule Peel Resistance Test," the corners (tops) of a triangular cross-section heat sealer are pressed against the surface of the packaging material to create a crease (crease) on the surface of the packaging material, and the packaging material is then folded in a mountain fold and then in a valley fold along the crease. After unfolding the packaging material, mending tape is applied to the crease, and the mending tape is then peeled off and the color ink peeling (color loss) is observed. The evaluation was given as "Good" if no color ink peeling occurred along the ruled line, "Good" if color ink peeling occurred on only part of the ruled line, and "Poor" if color ink peeling occurred over the entire ruled line.

[0032] In the "crush resistance test," the packaging material was held with both hands and crumpled five times so that the printed surfaces (OP layer 6) rubbed against each other. The crumpled packaging material was then unfolded and observed for peeling of the color ink (color loss). The number of white dots resulting from peeling of the color ink was counted, and the number of white dots (number of coating cracks) was evaluated as "Good" if 0 to 50 dots were present, "Average" if 51 to 100 dots were present, and "Poor" if 101 or more dots were present.

[0033] Referring to Table 1, it can be seen that in both the ruled line peeling resistance test and the rubbing resistance test, peeling (color loss) of the color ink is significantly reduced by laminating the anchor coat layer 4. The urethane resin contained in the anchor coat layer 4 improves the flexibility of the packaging material 1, which is thought to contribute to the reduction in peeling of the color ink.

[0034] Fig. 3 shows an enlarged photograph of the surface (OP layer 6 side) of the packaging material of Example 1 after the kneading resistance test, and Fig. 4 shows an enlarged photograph of the surface (OP layer 6 side) of the packaging material of Comparative Example 1 after the kneading resistance test. 2 Coated paper 2 is used.

[0035] As can be seen from a comparison between Figures 3 and 4, the packaging material 1 (Figure 3) laminated with the anchor coat layer 4 clearly shows less peeling of the color ink compared to the packaging material of Comparative Example 1 (Figure 4) which does not have the anchor coat layer 4 laminated thereto. Printing quality close to that of printing on a plastic film substrate can be achieved by using coated paper 2.

[0036] Since the packaging material 1 has little peeling of color ink even when bent, it can be suitably used for not only pillow-type packaging as shown in Figure 1, but also various types of packaging that form folds, such as gusset-type, three-sided, four-sided, and standing-type. [Explanation of symbols]

[0037] 1 Packaging material 2 Coated paper 2A paper layer 2B White pigment layer 3 Heat-seal layer 4 Anchor coat layer 5 color ink layer 6 Overprint layer (OP layer)

Claims

1. Coated paper, An anchor coat layer laminated on the coated surface of the coated paper, the anchor coat layer containing urethane resin and soluble nitrocellulose resin, the urethane resin content exceeding the soluble nitrocellulose resin content; An ink layer is laminated on the surface of the anchor coat layer. Paper print.

2. The anchor coat layer has a composition containing 99 to 68 wt% of urethane resin and 1 to 32 wt% of soluble nitrocellulose resin, the total of which is 100 wt%. The paper print according to claim 1.

3. The layer amount of the anchor coat layer is 1 g / m ２ That's all. The paper print according to claim 1.

4. an adhesive layer is laminated on the surface of the coated paper opposite to the surface on which the anchor coat layer is laminated; The paper print according to claim 1.

5. an overprint layer is laminated on the surface of the ink layer; The paper print according to claim 1.

6. An anchor coat layer containing urethane resin and soluble nitrocellulose resin, the urethane resin content exceeding the soluble nitrocellulose resin content, is laminated on the coated surface of the coated paper; An ink layer is laminated on the surface of the anchor coat layer. Method for producing paper printed matter.

7. The anchor coat layer has a composition containing 99 to 68 wt% of urethane resin and 1 to 32 wt% of soluble nitrocellulose resin, the total of which is 100 wt%. The method for producing a paper print according to claim 6.

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