Label roll and label

Abstract

To provide a label roll capable of producing a label in which formation of depressions causing appearance defects in a transparent printing layer is suppressed.SOLUTION: The present invention relates to a label roll formed by winding a label continuum having a base layer, a first printing layer laminated on a first surface of the base layer, and a second printing layer laminated on a second surface of the base layer opposite to the first surface. The first printing layer is a layer formed from a water-based ink containing a matting agent, the matting agent having an average particle diameter of 0.5 μm or more and 2.8 μm or less. The second printing layer is a layer formed from a water-based ink, is transparent, and has an arithmetic average roughness of a surface opposite to the base layer side of 0.21 μm or more and 0.8 μm or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a label roll formed by winding up a continuous label sheet in which a plurality of labels are continuously linked together. [Background technology]

[0002] Various labels bearing desired designs such as product names, pictures, and instructions are attached to products. To provide product information, design, and texture, various labels are printed using inks suited to their intended use. In recent years, there has been a demand for the development of environmentally friendly products, and water-based inks are also being sought for printing labels.

[0003] Patent Document 1 discloses a water-based flexographic ink for labels containing a specific binder resin, and a printed matter containing an ink layer formed using the water-based flexographic ink and a substrate. Patent Document 2 describes a water-based overprint varnish and water-based flexographic ink for shrink labels, both containing a specific binder resin. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2024-033426 [Patent Document 2] Japanese Patent Publication No. 2023-116301 Summary of the Invention [Problem to be solved by the invention]

[0005]

[0003] However, while aqueous inks have little environmental impact because they contain substantially no volatile organic solvents, the stability of the coating film formed in a wet state may be an issue. The present inventors attempted to provide a transparent printing layer made of aqueous ink on the inner surface of a label to ensure slipperiness when attached to a container, while providing a printing layer made of aqueous ink containing a matting agent on the outer surface of the label to impart a matte finish. However, they discovered that opaque marks were visible in areas that should be transparent, resulting in poor appearance. They found that this was due to the fact that when a printed continuous label web was wound up to form a label roll, the matting agent contained in the printing layer on the outer surface of the label was pressed against the transparent printing layer on the inner surface of the label, forming depressions, and causing diffuse reflection of light in these depressions.

[0006] Therefore, the present invention has been made in consideration of the above circumstances, and aims to provide a label roll that can produce labels having a configuration in which the inner surface of the label has a transparent printed layer made of water-based ink and the outer surface of the label has a printed layer formed using water-based ink containing a matting agent, and that can produce labels in which the formation of depressions in the transparent printed layer that cause poor appearance is suppressed even when the continuous label sheet after printing is wound up to form a label roll. [Means for solving the problem]

[0007] The present invention provides the following label rolls and labels. (1) The label roll of the present invention is a label roll formed by winding up a continuous label strip having a base layer, a first printed layer laminated on a first surface of the base layer, and a second printed layer laminated on a second surface of the base layer opposite to the first surface, wherein the first printed layer is a layer formed from an aqueous ink containing a matting agent, and the average particle diameter of the matting agent is 0.5 μm or more and 2.8 μm or less, and the second printed layer is a layer formed from an aqueous ink, and the arithmetic mean roughness of the surface opposite to the base layer side is 0.21 μm or more and 0.8 μm or less, and the second printed layer is transparent.

[0008] (2) In the label roll of the present invention, the maximum height of the surface of the second printing layer is 1.6 μm or more and 6.0 μm or less.

[0009] (3) The label of the present invention has a base layer, a first printed layer laminated on a first surface of the base layer, and a second printed layer laminated on a second surface of the base layer opposite the first surface, wherein the first printed layer is a layer formed from an aqueous ink containing a matting agent, and the average particle size of the matting agent is 0.5 μm or more and 2.8 μm or less, and the second printed layer is a layer formed from an aqueous ink, and the second printed layer has an arithmetic mean roughness of the surface of 0.21 μm or more and 0.8 μm or less, and is transparent.

[0010] (4) The label of the present invention is obtained by cutting from the continuous label strip unwound from the label roll described in (1) or (2). [Effects of the Invention]

[0011] According to the present invention, a label roll can be provided that, in a label having a configuration in which the inner surface of the label has a transparent printed layer made of an aqueous ink and the outer surface of the label has a printed layer formed using an aqueous ink containing a matting agent, even when a label roll is formed by winding up a continuous label sheet after printing, the label roll can produce labels in which poor appearance caused by depressions occurring in the transparent printed layer is suppressed. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view schematically showing the layer structure of a label according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention relates to a label roll formed by winding a continuous label strip having a base layer, a first printed layer laminated on a first surface of the base layer, and a second printed layer laminated on a second surface opposite the first surface of the base layer. The present invention also relates to labels obtained by cutting the continuous label strip unwound from the label roll. Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. In all of the drawings below, the scales of the components are appropriately adjusted to make them easier to understand, and the scales of the components shown in the drawings do not necessarily match the scales of the actual components.

[0014] [label] Fig. 1 is a cross-sectional view schematically illustrating the layer structure of a label according to one embodiment of the present invention. As shown in Fig. 1, the label 1 has a base layer 10, a first printed layer 20 laminated on a first surface 10a of the base layer 10, and a second printed layer 30 laminated on a second surface 10b of the base layer 10 opposite the first surface 10a. The first printed layer 20 is a layer formed from a water-based ink containing a matting agent 21. The second printed layer 30 is a transparent layer formed from a water-based ink. The first printed layer 20 and the second printed layer 30 form the outermost layers of the label 1.

[0015] The label 1 includes a design print layer 40 provided on at least a portion of the second surface 10b of the base layer 10. The design print layer 40 is a single or multiple print layer on which design indications such as product names, company names, instructions, designs, etc. are displayed in desired colors. In the label 1, the design print layer 40 can be provided on at least a portion of the first surface 10a or the second surface 10b of the base layer 10, and may be provided on both the first surface 10a and the second surface 10b.

[0016] The label 1 is used by attaching it to a container with the first printed layer 20 side facing outward and the second printed layer 30 side facing inward. The label 1 is given a matte finish by the first printed layer 20 containing the matting agent 21, the design printed layer 40 provides design and display information, and the second printed layer 30 provides slipperiness and abrasion resistance when attached to the container. The second printed layer 30 preferably contains a lubricant to provide slipperiness.

[0017] When the label 1 is viewed from the outside while attached to a container, the design and display information of the design printing layer 40 are visible, along with the matte finish of the first printing layer 20, contributing to improved design. On the other hand, the second printing layer 30 is usually invisible. Even if the base layer 10 is transparent, the design printing layer 40 on the second surface 10b of the base layer 10 is visible, but the second printing layer 30 is transparent and therefore usually invisible. However, if there are depressions on the surface 30a of the second printing layer 30 opposite the base layer 10, light may be diffused, resulting in cloudy marks in areas that should be transparent, resulting in poor appearance. Research into this issue revealed that when a printed label web is wound to form a label roll, depressions are formed on the surface 30a of the second printing layer facing the first printing layer 20 containing the matting agent 21, due to the matting agent 21 being embossed. Furthermore, the occurrence of such depressions is a particular issue with printing layers formed using water-based inks. This is because the printed layer formed with water-based ink is in a wet state after printing and is therefore prone to embossing.

[0018] After extensive research, the inventors have discovered that by setting the average particle diameter of the matting agent 21 contained in the first printing layer 20 to 0.5 μm or more and 2.8 μm or less, and the arithmetic mean roughness (hereinafter also referred to as surface roughness Ra2) of the surface 30a of the second printing layer 30 to 0.21 μm or more and 0.8 μm or less, even when the printed label web is wound up to form a label roll, the formation of depressions on the surface 30a of the second printing layer 30 is suppressed, and even if depressions are formed, poor appearance due to diffuse reflection of light can be suppressed, which led to the present invention.

[0019] The second printed layer 30 is transparent, and similarly, the first printed layer 20 and the base layer 10 are preferably transparent as well. When the first printed layer 20 and the base layer 10 are transparent, the label 1 is transparent in areas where the design printed layer 40 is not provided. When the second printed layer 30 is visible in this transparent area (when the second printed layer 30 is formed in the transparent area), poor appearance due to depressions on the surface 30a of the second printed layer 30 is visible, and the effect of the present invention is remarkable. The area where poor appearance due to depressions on the surface 30a of the second printed layer 30 of the label 1 of this embodiment can be visible is not limited to a "base layer / second printed layer" laminated and transparent area. For example, poor appearance can also be visible in the transparent area of ​​the "first printed layer / base layer / second printed layer," and a colored transparent layer may be laminated on the surface 30a of the second printed layer. On the other hand, if either the first printed layer 20 or the base layer 10 is not transparent, poor appearance due to depressions on the surface 30a of the second printed layer 30 is difficult to see, but application of the present invention is preferable from the viewpoint of improving label quality. In this specification, a "transparent layer" means a layer that is transparent enough to allow the adjacent layer behind it to be seen through the layer, and a "transparent label" means a state in which the volume of the contents of the container can be seen through the label when attached to a container. "Transparent" may mean either colorless transparent or colored transparent.

[0020] The matting agent 21 contained in the first printed layer 20 has an average particle size of 0.5 μm to 2.8 μm, preferably 0.6 μm to 2.5 μm, and more preferably 0.7 μm to 2.3 μm. When the average particle size of the matting agent 21 satisfies the above numerical range, even when the first printed layer 20 and the second printed layer 30 face each other in the label roll, it is possible to prevent the formation of depressions that cause poor appearance on the surface 30a of the second printed layer 30.

[0021] In this embodiment, the average particle diameter of the matting agent 21 is a value measured by analyzing an SEM image taken with a scanning electron microscope or the like using image analysis software. Here, the average particle diameter of the matting agent 21 is the number average of particle diameters of a plurality of particles observed and measured in the SEM image.

[0022] The surface roughness Ra2 of the surface 30a of the second printed layer 30 is 0.21 μm or more and 0.8 μm or less, preferably 0.22 μm or more and 0.7 μm or less, and more preferably 0.23 μm or more and 0.6 μm or less. When the surface roughness Ra2 satisfies the above numerical range, even when the first printed layer 20 and the second printed layer 30 face each other in the label roll, it is possible to prevent the formation of dents on the surface 30a of the second printed layer 30 that cause poor appearance.

[0023] In this embodiment, the arithmetic mean roughness (Ra), maximum height (Ry), and ten-point mean roughness (Rz) of the layer surface are values ​​measured by a method conforming to JIS B 0601-1994. For example, they are measured by measuring any location on the layer surface using a surface roughness measuring device (HandySurf E-35A, manufactured by Tokyo Seimitsu Co., Ltd.) by the surface scanning method conforming to JIS B 0601-1994.

[0024] When a design printing layer 40 is provided on the second surface 10b of the base layer 10, the second printing layer 30 is preferably provided so as to cover the design printing layer 40 in order to impart slipperiness. Furthermore, in order to stabilize the slipperiness of the label, it is more preferable that the second printing layer 30 is provided so as to cover the design printing layer 40 and areas where the design printing layer 40 is not present. When a design printing layer is provided on the first surface 10a of the base layer 10 (not shown), the formation area of ​​the first printing layer 20 can be selected appropriately depending on the design, and the first printing layer 20 may be provided so as to cover the design printing layer, or may be provided intermittently in areas where the design printing layer is present so that the first printing layer 20 is not present.

[0025] The label and continuous label strip of the present invention preferably have the layer structure of the present invention, i.e., "first printed layer 20 / base layer 10 / second printed layer 30," in at least a portion of the label. For example, while the second printed layer 30 in the layer structure of the present invention is transparent, the label and continuous label strip of the present invention may have a region of an opaque printed layer (e.g., a white printed layer) in the area where the second printed layer 30 is not present, or may have a region with a layer structure of "first printed layer 20 / base layer 10 / opaque printed layer." In this case, like the second printed layer 30, the opaque printed layer is preferably a layer containing a lubricant to provide slipperiness when the container is attached. For example, while the first printed layer 20 in the layer structure of the present invention contains a matting agent 21, the area where the first printed layer is not present may have a region of a printed layer that does not contain a matting agent, and the label and continuous label strip of the present invention may have a region with a layer structure of "printed layer not containing a matting agent / base layer 10 / second printed layer 30." The outermost layer includes a first printed layer 20 containing a matting agent 21 and a printed layer that does not contain a matting agent, which creates a difference in gloss on the surface of the layer between the part containing the matting agent and the part not containing the matting agent, thereby enabling the three-dimensional effect of designs, characters, etc. to be more prominently expressed.

[0026] <Base material layer> The substrate layer in this embodiment may be a thermoplastic label substrate, such as a heat-shrinkable or non-heat-shrinkable label substrate. Examples include polyester films made of polyester resins such as polyethylene teretaphthalate resins and polylactic acid resins; polystyrene films made of polystyrene resins such as styrene-butadiene block copolymers; polyolefin films made of olefin resins such as polyethylene and polypropylene; and polyvinyl chloride films made of vinyl chloride resins. Heat-shrinkable label substrates preferably have a heat shrinkage rate of 30% or more, and more preferably 45% or more, in at least one direction when immersed in hot water at 90°C for 10 seconds. Non-heat-shrinkable label substrates preferably have a heat shrinkage rate of less than 5%, and more preferably 3% or less, in both directions when immersed in hot water at 90°C for 10 seconds.

[0027] The substrate layer of this embodiment is preferably a transparent substrate layer, which allows for visual confirmation of appearance defects resulting from depressions on the surface 30a of the second printed layer 30.

[0028] The thickness of the base layer 10 in this embodiment may be 10 μm or more and 100 μm or less, or may be 12 μm or more and 60 μm or less.

[0029] <1st printing layer> In this embodiment, the first printing layer 20 is provided on the first surface 10a of the base material layer 10 and is formed from an aqueous ink containing a matting agent 21. The first printing layer 20 can be formed, for example, by plate printing. In this embodiment, "plate printing" refers to a printing method in which printing is performed using a plate. Examples of plate printing include relief printing, intaglio printing, lithographic printing, and stencil printing. In this embodiment, the first printing layer 20 is preferably formed on the base material layer 10 by relief printing or intaglio printing, and more preferably formed on the base material layer 10 by relief printing (flexographic printing).

[0030] The first printed layer 20 in this embodiment can impart a matte finish to the label surface, and therefore may be provided on the entire or part of the first surface 10a of the base material layer 10. The first printed layer 20 is preferably provided partially on the first surface 10a of the base material layer 10. The first printed layer 20 is a layer that forms the outermost layer of the label 1. Furthermore, when the first printed layer 20 is provided partially on the first surface 10a of the base material layer 10, the first surface 10a of the base material layer 10 and the first printed layer 20 form the outermost layer of the label 1.

[0031] The first printed layer 20 is a layer made of water-based ink containing a matting agent 21, and is a layer that can impart a matte finish to the surface of the label. Types of matting agents 21 that can be used include organic particles such as acrylic beads, hollow acrylic beads, and melamine resin, and inorganic particles such as silica, alumina, calcium carbonate, and barium sulfate. These matting agents 21 may be used alone or in combination of two or more.

[0032] The first printed layer 20 may contain 10% by mass or more and 80% by mass or less, or 15% by mass or more and 70% by mass or less, of the matting agent 21 relative to the total solid content of the first printed layer 20. When the content of the matting agent 21 contained in the first printed layer 20 is within the above numerical range, the occurrence of poor appearance can be further suppressed.

[0033] The arithmetic mean roughness (hereinafter also referred to as surface roughness Ra1) of the surface 20a of the first printing layer 20 opposite the base layer 10 side may be less than 0.38, less than 0.35, or even less than 0.33. When the surface roughness Ra1 satisfies the above numerical range, the formation of depressions that cause poor appearance in the second printing layer 30 that faces the label roll can be further suppressed. The lower limit of the surface roughness Ra1 is not particularly limited and may be, for example, 0.1 or more, or 0.15 or more.

[0034] The maximum height of the surface 20a of the first printed layer 20 (hereinafter also referred to as maximum height Ry1) may be less than 3.0, less than 2.5, or less than 2.2. When the maximum height Ry1 satisfies the above numerical range, the formation of depressions that cause poor appearance in the second printed layer 30 that faces the label roll can be further suppressed. The lower limit of the maximum height Ry1 is not particularly limited and may be, for example, 0.2 or more, or 0.5 or more.

[0035] The ten-point average roughness (hereinafter also referred to as average roughness Rz1) of the surface 20a of the first printing layer 20 may be less than 2.1, less than 2.0, or less than 1.9. When the average roughness Rz1 satisfies the above numerical range, the formation of depressions that cause poor appearance in the second printing layer 30 that faces the label roll can be further suppressed. The lower limit of the average roughness Rz1 is not particularly limited and may be, for example, 0.2 or more, or 0.5 or more.

[0036] The thickness of the first printed layer 20 may be 0.1 μm or more and 10 μm or less, or 0.2 μm or more and 5 μm or less. When the thickness of the first printed layer 20 is within the above numerical range, the matting agent 21 contained in the first printed layer 20 can further prevent the second printed layer 30, which faces the first printed layer 20 on the label roll, from forming depressions that cause poor appearance.

[0037] For the surface 20 a of the first printed layer 20 , the above Ra1, Ry1, and Rz1 can be appropriately achieved by adjusting the average particle size and content of the matting agent 21 and the thickness of the first printed layer 20 .

[0038] The aqueous ink forming the first printing layer 20 contains a matting agent 21 and other components commonly found in aqueous inks, such as water, a water-soluble organic solvent, a resin, and a colorant. Water serves as a solvent or dispersion medium for the aqueous ink. The aqueous ink may be mixed with a water-soluble organic solvent such as alcohol to provide drying properties to the ink. Examples of the resin include cellulose resin, styrene resin, acrylic resin, urethane resin, and vinyl resin.

[0039] The colorant may be any known colorant, such as inorganic pigments such as titanium dioxide, red iron oxide, barium sulfate, calcium carbonate, silica, zinc oxide, zinc sulfide, mica, talc, and pearl; organic pigments such as phthalocyanine, insoluble azo, condensed azo, dioxazine, anthraquinone, quinacridone, perylene, perinone, thioindigo, and carbon black; and dyes such as yellow disperse dyes, orange disperse dyes, red disperse dyes, violet dyes, green disperse dyes, brown disperse dyes, blue disperse dyes, and black disperse dyes. The first printed layer 20 is preferably transparent. Therefore, it is preferable that the first printed layer 20 contains no colorants other than the matting agent 21. If the first printed layer 20 contains a colorant other than the matting agent 21, the colorant is preferably present in an amount sufficient to maintain the transparency of the first printed layer 20.

[0040] The first printed layer 20 may contain other components within the scope that does not impair the effects of the present invention. Examples of such other components include anti-settling agents, antifoaming agents, dispersants, stabilizers, fillers, antioxidants, UV absorbers, antistatic agents, color-changing inhibitors, fragrances, and deodorizers.

[0041] <2nd printing layer> The second printed layer 30 in this embodiment is provided on the second surface 10b of the base layer 10 and is formed from a water-based ink. The second printed layer 30 in this embodiment can stabilize the slipperiness of the label, and may be provided on all or part of the second surface 10b of the base layer 10. From the viewpoint of providing slipperiness, the second printed layer 30 is preferably provided on 80% or more of the entire surface of the second surface 10b of the base layer 10, more preferably 85% or more, even more preferably 90% or more, and most preferably the entire surface.

[0042] The arithmetic mean roughness (Ra) of the surface 30a of the second printed layer 30 is 0.21 μm or more and 0.8 μm or more. The second printed layer 30 is provided on the second surface 10b of the base layer 10 by plate printing or plateless printing using an aqueous ink. In this embodiment, "plateless printing" refers to a printing method in which printing is performed without using a plate. The backside layer in this embodiment is preferably formed by plate printing such as relief printing, intaglio printing, lithographic printing, and stencil printing, or plateless printing such as laser printing and inkjet printing, more preferably by relief printing and intaglio printing, and even more preferably by relief printing (flexographic printing).

[0043] The second printed layer 30 preferably contains a lubricant to provide slipperiness. The aqueous ink forming the second printed layer 30 can be a commonly used aqueous ink minus the colorant (hereinafter, such ink will also be referred to as "aqueous medium ink"). Components of aqueous medium ink include water, a water-soluble organic solvent, a resin, a lubricant, etc. Water serves as the solvent for the aqueous ink. The aqueous ink may be mixed with a water-soluble organic solvent such as alcohol to provide drying properties. Examples of the resin include cellulose resin, styrene resin, acrylic resin, urethane resin, vinyl resin, etc. Examples of the lubricant include at least one selected from the group consisting of polyethylene-based lubricants such as polyethylene wax, oxidized polyethylene wax, and fluorine-modified polyethylene wax; polypropylene-based lubricants such as polypropylene wax; polyester-based lubricants such as polyethylene terephthalate wax; and fluorine-based lubricants such as polytetrafluoroethylene wax. Among these, the lubricant preferably contains a polyethylene-based wax or a polypropylene-based lubricant.

[0044] The maximum height of the surface 30a of the second printed layer 30 (hereinafter also referred to as maximum height Ry2) may be 1.6 or more and 6.0 or less, or 1.8 or more and 5.0 or less. When the maximum height Ry2 satisfies the above numerical range, the transparency of the second printed layer 30 can be maintained.

[0045] The ten-point average roughness (hereinafter also referred to as average roughness Rz2) of the surface 30a of the second printed layer 30 may be 1.20 or more and 4.0 or less, or 1.30 or more and 3.5 or less. When the average roughness Rz2 satisfies the above numerical range, the transparency of the second printed layer 30 can be maintained.

[0046] The thickness of the second printed layer 30 may be 0.1 μm or more and 10 μm or less, 0.2 μm or more and 8.0 μm or less, or 0.3 μm or more and 5.0 μm or less. By having the thickness of the second printed layer 30 within the above numerical range, it is possible to reduce the thickness of the entire label while imparting slipperiness.

[0047] <Design printing layer> The design printing layer 40 is a layer that displays visible images, characters, etc., and the presence of the design layer results in a label with excellent appearance. The design printing layer may be a colored transparent layer or a colored opaque layer. The design printing layer may be formed using a known colorant alone or a combination of two or more types. The design printing layer 40 can be formed using known printing inks and various printing methods such as gravure printing. The thickness of the design layer can be, for example, 0.5 μm or more and 5 μm or less.

[0048] The best form of the label of this embodiment is one in which the first printing layer is partially disposed on the first surface of the base layer, the base layer is transparent, the design printing layer is partially disposed on the second surface of the base layer, thereby having a transparent area without a design printing layer, and the second printing layer is transparent and disposed over the entire second surface of the base layer.

[0049] [Label continuum, label roll] The above-mentioned labels are obtained by cutting out sheets from a continuous label strip. The continuous label strip is formed by connecting at least a plurality of the above-mentioned labels in the longitudinal direction, and is, for example, a long strip of 500 m to 20,000 m. The continuous label strip is then wound up into a label roll for storage, transportation, etc.

[0050] The continuous label strip is manufactured by forming a first printed layer using an aqueous ink on one surface of a long substrate, and forming a second printed layer using an aqueous ink on the other surface of the substrate. The printing method for the first printed layer and the second printed layer is as described above. Here, the printing order of the first printed layer and the second printed layer is not limited. It is preferable that the next printed layer is formed after the previously formed printed layer has solidified by drying, curing, or the like. The manufactured continuous label strip is wound into a roll and stored, transported, etc. as a label roll. When the continuous label strip is wound into a roll, the first printed layer 20 may be on the inside, or the second printed layer 30 may be on the inside. From the viewpoint of visually confirming the effect of the matte-finished layer, the continuous label strip is preferably wound with the second printed layer 30 on the inside.

[0051] Labels are obtained by unwinding a continuous label strip from a label roll and cutting it into individual labels. The continuous label strip can be cut, for example, by a slitting machine having one or more cutting edges, and the continuous label strip can be cut into individual labels or multiple labels at the same time. [Example]

[0052] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the examples and comparative examples, the blending amounts expressed as "%" and "parts" are by mass % and parts by mass unless otherwise specified.

[0053] (1) Preparation of water-based ink for the first printing layer An acrylic matte ink for water-based flexographic printing was used as water-based ink A. Water-based ink A contained a silica-containing matting agent in an amount of 36% by mass based on the entire dried coating film of the ink. Water-based ink B was used an acrylic matte ink for water-based flexographic printing in which the average particle size of the matting agent was different from that of water-based ink A. Water-based ink B contained a silica-containing matting agent in an amount of 36% by mass based on the entire dried coating film of the ink.

[0054] (2) Preparation of water-based ink for the second printing layer Water-based ink C used an acrylic backing medium ink containing polyethylene wax as a lubricant. When the water-based ink C dried, the lubricant was contained in an amount of 7% relative to the entire coating film. Water-based ink D used an acrylic backing medium ink containing polyethylene wax with a different average particle size than water-based ink C as a lubricant. When the water-based ink D dried, the lubricant was contained in an amount of 7% relative to the entire coating film.

[0055] (3) Making label rolls Example 1 First, a first printing layer was formed by printing aqueous ink A on the substrate. The substrate was a polystyrene shrink film (product name 27041S, manufactured by Mitsubishi Chemical Corporation). The first printing layer was formed by partially applying aqueous ink A to the substrate layer using a flexographic printing plate. Next, the second printing layer was formed by applying aqueous ink C to the entire surface of the substrate layer on which the first printing layer was not formed using a flexographic printing plate. In this way, a continuous label strip was produced consisting of [first printing layer (aqueous ink A, thickness: 0.7 μm) / substrate layer (thickness: 40 μm) / second printing layer (aqueous ink C, thickness: 0.5 μm)]. The continuous label strip was then wound up with the second printing layer facing inward to produce a label roll.

[0056] <Comparative Example 1> A continuous long label strip was produced in the same manner as in Example 1, except that the first printed layer was formed using water-based ink B instead of water-based ink A, with the structure of [first printed layer (water-based ink B, thickness: 0.7 μm) / base layer (thickness: 40 μm) / second printed layer (water-based ink C, thickness: 0.5 μm)].

[0057] <Comparative Example 2> A long label print was produced in the same manner as in Example 1, except that the second printed layer was formed using aqueous ink D instead of aqueous ink C, with the structure of [first printed layer (aqueous ink A, thickness: 0.7 μm) / base layer (thickness: 40 μm) / second printed layer (aqueous ink D, thickness: 0.5 μm)].

[0058] <Comparative Example 3> A continuous linear label strip consisting of [first printed layer (water-based ink B, thickness: 0.7 μm) / base layer (thickness: 40 μm) / second printed layer (water-based ink D, thickness: 0.5 μm)] was produced in the same manner as in Example 1, except that water-based ink B was used instead of water-based ink A and water-based ink D was used instead of water-based ink C.

[0059] (4) Measurement of each parameter <Surface roughness> A 10 mm x 10 mm test piece was cut out from the label roll, and the Ra, Ry, and Rz of the first surface of the first printed layer and the Ra, Ry, and Rz of the first surface of the second printed layer of the test piece placed on a flat table were measured using a surface roughness measuring device (HandySurf E-35A, manufactured by Tokyo Seimitsu Co., Ltd.) in accordance with JIS B 0601-1994. The measurement results are shown in Table 1.

[0060] <Average particle size of matting agent> An SEM image of the first surface of the first printing layer of the label roll was taken using a scanning electron microscope (TM3030 Plus, manufactured by Hitachi High-Tech Corporation). Ten matting agents were randomly selected from the SEM image, and the particle size of each matting agent was measured. The average particle size of the matting agent was calculated as the number-average value of the particle sizes of the ten matting agents selected.

[0061] (5) Evaluation The label rolls obtained in the examples and comparative examples were evaluated as follows. The evaluation results are shown in Table 2.

[0062] <Exterior visibility> The label rolls of the examples and comparative examples were left to stand for 24 hours at 23° C.±2° C. After that, the continuous label strip was pulled out from the label roll, and the presence or absence of cloudy marks was visually confirmed from the first printed layer side. +: No cloudiness -: There are cloudy marks

[0063] [Table 1]

[0064] [Table 2]

[0065] From the results in Table 2, no cloudy marks were observed in the continuous label strip of Example 1. On the other hand, cloudy marks were observed and poor appearance occurred in the continuous label strips of Comparative Examples 1 to 3. From the above results, it was found that the continuous label strips of the Examples had good appearance visibility.

[0066] The embodiments and examples disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the above-described embodiments and examples, and is intended to include all documents within the scope and meaning equivalent to the claims. [Explanation of symbols]

[0067] 1 Label, 10 Base layer, 10a First surface of base layer, 10b Second surface of base layer, 20 First printing layer, 20a Surface of first printing layer, 21 Matting agent, 30 Second printing layer, 30a Surface of second printing layer, 40 Design printing layer.

Claims

1. A label roll formed by winding up a continuous label strip having a base layer, a first printed layer laminated on a first surface of the base layer, and a second printed layer laminated on a second surface of the base layer opposite to the first surface, the first printed layer is a layer formed from a water-based ink containing a matting agent, the average particle size of the matting agent is 0.5 μm or more and 2.8 μm or less; the second printed layer is a layer formed from a water-based ink, The second printing layer has an arithmetic mean roughness of 0.21 μm or more and 0.8 μm or less on the surface opposite to the base layer side, and is transparent.

2. The label roll according to claim 1 , wherein the maximum height of the surface of the second printing layer is 1.6 μm or more and 6.0 μm or less.

3. a base layer, a first printed layer laminated on a first surface of the base layer, and a second printed layer laminated on a second surface of the base layer opposite to the first surface; the first printed layer is a layer formed from a water-based ink containing a matting agent, the average particle size of the matting agent is 0.5 μm or more and 2.8 μm or less; the second printed layer is a layer formed from a water-based ink, The second printing layer has an arithmetic mean roughness of the surface of 0.21 μm or more and 0.8 μm or less, and is transparent.

4. The label according to claim 3, wherein the label is obtained by cutting from the continuous label strip unwound from the label roll according to claim 1 or 2.

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