JP7154923B2 - Paperboard, processed paperboard, and method for producing processed paperboard - Google Patents

Description

The present invention relates to paperboard, converted paperboard, and methods of making converted paperboard.

Paperboard is a relatively thick paper having multiple layers of paper and is used for paper containers, packaging materials, building materials, and the like. In paperboard, various developments have been made to improve performance such as strength. For example, in Japanese Unexamined Patent Application Publication No. 2006-241628, as a base paper for a laminated sheet paper box that does not cause buckling or deformation, prevents buckling during transportation, and prevents sheets from falling off, etc., A paperboard in which the density of each paper layer is limited to a predetermined range has been proposed. In addition, in JP-A-2008-127703, it has excellent heat insulation and heat retention, and is excellent in processing, bonding, and box making suitability for cardboard sheets, cardboard packaging containers, interior packaging containers, etc., and printing. As a multi-layer paperboard with excellent suitability, a paperboard has been proposed in which a coating liquid containing at least hollow inorganic particles, thermally expandable particles and a binder is applied to at least one side of a base paper to provide a coating layer. there is

Japanese Patent Application Laid-Open No. 2006-241628 JP 2008-127703 A

Paperboards are sometimes subjected to various surface treatments from the viewpoints of beauty, fashion, sales promotion, and the like. For example, in boxes for packaging high-class confectionery, food, shoes, accessories, etc., there are cases in which letters and figures are stamped with metal foil on the lid of the box to give a high-class feeling. This foil stamping operation is generally performed by foil stamping the paperboard before the lid is assembled using a foil stamping press. Foil stamping is accomplished by thermally transferring a metal layer provided on a film to the surface of the paperboard. However, when foil stamping is applied to conventional paperboard with a matte surface, which has been adopted as a means of creating a sense of luxury in recent years, the foil does not adhere uniformly and sufficiently. You may not be able to press it.

The present invention has been made based on the above circumstances, and its purpose is to provide paperboard with reduced luster (gloss) and excellent suitability for foil stamping, processed paperboard using such paperboard, and to provide a method for manufacturing converted paperboard.

An invention made to solve the above problems is a paperboard having a surface layer, a back layer, and one or more intermediate layers disposed between the surface layer and the back layer, wherein the surface on the surface side is The paperboard has a ten-point average roughness (Rz) of 14 μm or more and 20 μm or less and a PPS smoothness of 6 or more and 10 or less.

The paperboard has a ten-point average roughness (Rz) of 14 μm or more and 20 μm or less and a PPS smoothness of 6 μm or more and 10 μm or less on the surface of the paperboard, so that the luster is suppressed and it is excellent in foil stamping suitability. That is, when the paperboard is subjected to foil stamping, it is possible to perform foil stamping that is excellent in cosmeticity while producing a high-class feeling with little unevenness. The reason for this is not clear, but is presumed as follows. In the paperboard, the surface on the surface side (surface) has a ten-point average roughness (Rz) of 14 μm or more and a PPS smoothness of 6 μm or more, which is a relatively rough surface. In this way, when the surface has moderate unevenness, the heat insulation and heat retention properties of the paperboard surface layer are enhanced, and when the paperboard is heat-pressed with a foil stamping press, it is difficult for heat to escape from the heat-pressed part of the paperboard. Only the part where the As a result, the heat-pressed portion of the foil is transferred to the surface of the paperboard with high uniformity. Conversely, if the surface of the paperboard has little unevenness and the heat insulation and heat retention properties of the surface layer are low (the heat transfer of the surface layer is high), when the paperboard is heat-pressed with a foil stamping press, the heat-pressed part of the paperboard will Heat escapes easily. In this case, the heat-pressed portion of the foil may not be transferred sufficiently, or even the non-heat-pressed portion of the foil may be transferred, making it difficult to perform good foil stamping according to the plate. In addition, since the paperboard has a relatively rough surface, it is excellent in mattness and gives a sense of quality. On the other hand, when the ten-point average roughness (Rz) of the surface exceeds 20 μm, or when the PPS smoothness exceeds 10 μm, the unevenness of the surface is too large, and a difference in pressure and temperature tends to occur when thermocompression bonding is performed. As a result, unevenness tends to occur in the transferred foil.

Preferably, the surface layer has an ash content of 9% by mass or more and a mechanical pulp content of 50% by mass or more. When the ash content of the surface layer is 9% by mass or more, the flatness of the surface layer is moderately improved, and surface properties with suppressed luster are easily obtained, and a foil surface with less unevenness is easily formed. Furthermore, since the content of mechanical pulp is 50% by mass or more, the ratio of raw material pulp fibers without concentric sag increases, and it has excellent heat insulation and cushioning properties, so it can be hot during foil stamping. Excellent suitability for stamping.

It is preferable that the surface layer contains hollow waste paper as waste paper preferable for making the ash content of the surface layer 9% by mass or more and the mechanical pulp content ratio 50% by mass or more. Recycled white paper is mainly composed of mechanical pulp, and unlike kraft pulp, there is little deterioration or flattening of the fibers. Also, waste paper has a relatively high ash content. Therefore, by using recycled white paper with a high mechanical pulp content and a relatively high ash content in the surface layer, it is possible to form a flexible and bulky paper layer, which has high heat insulation and heat retention, and is suitable for foil stamping. can be enhanced. In addition, since it has a high ash content, it also has the advantage of increasing the flatness of the foil stamping portion during foil stamping, leading to an improvement in foil stamping aptitude and increasing the mattness. In addition, white waste paper containing 50% by mass or more of calcium carbonate as the proportion of inorganic substances contained in ash has a high degree of whiteness derived from calcium carbonate, has good compatibility with coloring agents, and has the effect of improving the appearance.

As described above, the paperboard has a suppressed luster and is excellent in foil stamping aptitude, so that it can be suitably used as a paperboard for foil stamping.

Another invention made to solve the above problems is a processed paperboard comprising the paperboard and a foil crimped to a part of the surface of the paperboard. Since the processed paperboard is obtained by subjecting the surface of the paperboard of the present invention to foil stamping, the foil stamping is excellent with little unevenness, and the gloss of the portion not subjected to foil stamping is suppressed. Therefore, it has excellent cosmetic properties.

Another invention made to solve the above-mentioned problems is a method for producing a processed paperboard, comprising a step of foil-stamping the surface of the paperboard. According to this manufacturing method, it is possible to obtain a processed paperboard that is foil-stamped with little unevenness and that has a reduced luster in the parts that are not foil-stamped, and thus has excellent cosmetic properties.

ADVANTAGE OF THE INVENTION According to this invention, the luster is suppressed and the manufacturing method of the processed paperboard and the processed paperboard using such a paperboard which is excellent in foil-stamping aptitude can be provided.

Hereinafter, a paperboard, a processed paperboard, and a method for producing a processed paperboard according to an embodiment of the present invention will be described in detail.

<Paperboard>
A paperboard according to one embodiment of the present invention has a top layer, a back layer, and one or more intermediate layers disposed between the top layer and the back layer. Each layer is a paper layer whose main component is pulp fiber.

(surface)
The surface layer is a single paper layer located on the outermost surface. The pulp fiber that is the main component of the surface layer is not particularly limited. TMP, pressureized kraft pulp: PGW, refiner ground pulp: RGP, ground pulp, etc.) and pulp fibers obtained from non-wood pulps such as kenaf, bagasse, hemp, and cotton. Among these, waste paper pulp is preferable, and waste paper pulp containing a large amount of mechanical pulp and containing 9% by mass or more of ash is more preferable.

Waste paper pulp raw materials include, for example, white waste paper, ruled white waste paper, card waste paper, special white waste paper, medium white waste paper, cut waste paper, used paper, imitation waste paper, Kent waste paper, white art waste paper, waste newspaper paper, waste magazine paper, Used paper such as land certificates can be mentioned. Two or more of these waste papers may be used. Among these, it is preferable to use recycled white paper in the surface layer. Unprinted waste paper conforms to the waste paper statistical classification in the waste paper handbook published by the Waste Paper Recycling Promotion Center. say. Therefore, white waste paper originally has few printed parts that require deinking and bleaching treatment, has a high degree of whiteness, and is a waste paper that contains a large amount of mechanical pulp with little fatigue. Due to the high content of mechanical pulp with little fatigue, the surface tends to be rough, and the surface ten-point average roughness (Rz) and PPS smoothness are within a predetermined range, and the heat insulation and heat retention are high, and the bulkiness is high. surface layer is easily formed. In addition, recycled white paper has a high ash content and, in particular, a high calcium oxide content. For this reason, by using hollow waste paper for the surface layer, heat insulation and heat retention can be enhanced, and effects such as suitability for foil stamping and matting can be further enhanced.

The lower limit of the content ratio of hollow waste paper in the pulp fibers of the surface layer is preferably 50% by mass, preferably 70% by mass, more preferably 90% by mass, and even more preferably 99% by mass. In this way, by forming the surface layer substantially from recycled white paper, effects such as foil stamping suitability and matting properties can be further enhanced. The upper limit of the content of the recycled white paper is preferably 100% by mass.

The lower limit of the mechanical pulp content in the surface layer is preferably 50% by mass from the viewpoint of further enhancing foil stamping suitability. On the other hand, the upper limit of the mechanical pulp content is preferably 90% by mass, more preferably 80% by mass. The mechanical pulp contained in the surface layer is preferably mechanical pulp contained in waste paper pulp such as hollow waste paper.

The lower limit of the ash content of the surface layer, measured according to JIS-P-8251 "Paper, paperboard and pulp-ash content test method-525 ° C combustion method", is preferably 9% by mass, more preferably 10% by mass. preferable. By making the ash content of the surface layer equal to or higher than the above lower limit, the matte property and the like can be further enhanced. On the other hand, the upper limit of this distribution is preferably 20% by mass, more preferably 15% by mass, and even more preferably 12% by mass. The presence of inorganic components is a factor that lowers the heat insulating properties. Therefore, by making the ash content of the surface layer equal to or less than the above upper limit, it is possible to enhance heat insulating properties and heat retention properties and to improve foil stamping suitability.

The content of calcium oxide in the ash of the surface layer is preferably 50% by mass or more and 75% by mass or less, the content of aluminum oxide is preferably 5% by mass or more and 12% by mass or less, and the content of silicon oxide is preferably , 10% by mass or more and 18% by mass or less. By adopting an ash composition with a high content of calcium oxide in this way, it is possible to further enhance the suitability for foil stamping, the matting property, and the like. The content ratio in the ash referred to here is the ratio of each element detected in terms of oxide in elemental analysis of ash particles by an X-ray microanalyzer.

In addition to pulp fibers, the surface layer may contain conventionally known additives such as pigments, dyes, aluminum sulfate, internal sizing agents, and internal paper strength agents.

(back layer)
The backing layer is a single layer of paper positioned on the backmost side. Pulp fibers that are the main component of the back layer may be the same as those exemplified for the surface layer. Among these, it is preferable to use waste paper pulp, and it is more preferable to use ground certificate waste paper. The back layer may contain various additives similar to those of the surface layer. Among the various types of waste paper pulp, denote waste paper is a waste paper raw material with a relatively high ash content, similar to medium waste paper. It is a waste paper raw material suitable for foil stamping.

(middle layer)
The middle layer is a paper layer that is placed between the face layer and the back layer. The number of layers of the intermediate layer is not particularly limited, and can be, for example, 1 to 5 layers, preferably 3 layers. Pulp fibers that are the main component of the back layer may be the same as those exemplified for the surface layer. Among these, it is preferable to use waste paper pulp, and it is more preferable to use ground certificate waste paper as in the back layer. The intermediate layer may contain various additives similar to those of the surface layer.

(surface treatment)
The paperboard may be surface-treated. For example, the surface can be treated by applying a coating liquid containing a surface sizing agent, an anti-slip agent, a water repellent, etc. to the surface layer surface. However, it is preferable that the surface of the paperboard is not surface-treated with a coating liquid containing a surface sizing agent. In addition, it is preferable that the paperboard is not subjected to flattening treatment such as calendering, or is subjected to calendering by its own weight. By not applying a surface sizing agent and not performing a flattening treatment in this way, it becomes easier to keep the surface ten-point average roughness (Rz) and the PPS smoothness within a predetermined range.

(Production method)
Although the method for producing the paperboard is not particularly limited, the paperboard can be produced, for example, by the following steps using a known multilayer paper machine.
(1) A slurry obtained by dispersing pulp fibers in water is mixed with an additive corresponding to each paper layer as necessary to prepare a stock for each paper layer.
(2) Each paper stock is made on a wire and made together.
(3) Pressing with pressure rolls to remove moisture.
(4) Dry with a dryer cylinder, and apply a coating liquid if necessary.
(5) Take up on a reel to obtain colored paperboard.

In the paperboard manufacturing method, a flattening treatment such as calendering may be performed, but it is preferable not to perform a flattening treatment as described above. As a result, the ten-point average roughness (Rz) and PPS smoothness of the surface (surface) on the surface layer side can be adjusted to relatively large values. In addition, the ten-point average roughness (Rz) and PPS smoothness of the surface on the surface layer side can be adjusted by performing calendering and adjusting the linear pressure and the like at this time.

(quality, etc.)
The lower limit of the ten-point average roughness (Rz) of the surface of the paperboard is 14 μm, preferably 15 μm. By making the ten-point average roughness (Rz) of the surface equal to or higher than the above lower limit, heat insulating properties and heat retention properties are enhanced, and foil stamping suitability is improved. In addition, by roughening the surface, mattness is also enhanced. On the other hand, the upper limit of the ten-point average roughness (Rz) is 20 μm. By setting the ten-point average roughness (Rz) of the surface to the above upper limit or less, it is possible to prevent the unevenness of the surface from becoming too large, and to perform foil stamping with little transfer unevenness. The ten-point average roughness (Rz) is measured in accordance with JIS-B-0601:1994 "Product Geometric Characteristic Specification (GPS)-Surface Texture: Contour Curve Method-Terms, Definitions and Surface Texture Parameters". value.

The lower limit of the PPS smoothness of the surface of the paperboard is 6 μm, preferably 6.2 μm, more preferably 7.4 μm. By making the PPS smoothness of the surface equal to or higher than the above lower limit, heat insulating properties and heat retention properties are enhanced, and foil stamping suitability is improved. In addition, by roughening the surface, mattness is also enhanced. PPS smoothness is an index that indicates the degree of smoothness from the amount of air flow, and by applying pressure to the measurement head and measuring it, it is possible to reproduce the state of foil stamping and measure the smoothness at the time of foil stamping. Therefore, it is suitable as an index related to the foil stamping aptitude of the present invention. The upper limit of the PPS smoothness of the surface of the paperboard is 10 μm. By setting the PPS smoothness of the surface to the above upper limit or less, it is possible to prevent the unevenness of the surface from becoming too large, and to perform foil stamping with little transfer unevenness. The PPS smoothness conforms to Appendix A of JIS-P-8151-2004, model name: SE-115 manufactured by Lorentzen & Bettley Co., Ltd., using a soft rubber backing disc, Print Surf surface roughness (μm) measured on the surface layer at a clamping pressure of 1 MPa.

The upper limit of the Bekk smoothness of the surface of the paperboard is preferably 20 seconds. By making the Bekk smoothness of the surface equal to or less than the above upper limit, heat insulation and heat retention properties are enhanced, and foil stamping aptitude is improved. On the other hand, the lower limit of the Bekk smoothness may be, for example, 5 seconds, preferably 8 seconds. The Bekk smoothness is a value measured according to JIS-P-8119-1998.

The lower limit of the basis weight of the paperboard is, for example, preferably 150 g/m ² , more preferably 165 g/m ² . By making the basis weight equal to or higher than the above lower limit, there is a tendency that the aptitude for foil stamping is further enhanced. On the other hand, the upper limit of this basis weight is preferably 200 g/m ² , more preferably 180 g/m ² . By setting the basis weight to the above upper limit or less, the weight can be reduced, and workability and the like are also improved.

The lower limit of the ash content of the paperboard (whole) is preferably 10% by mass, more preferably 15% by mass. By making the ash content equal to or higher than the above lower limit, the matting property can be enhanced. On the other hand, the upper limit of the ash content is preferably 25% by mass, more preferably 20% by mass. By making the ash content equal to or less than the above upper limit, it is possible to improve the suitability for foil stamping.

The surface electrical resistance of the surface of the paperboard is preferably 4.0×10 ¹² Ω or more. When the surface electric resistance is 4.0×10 ¹² Ω or more, corrosion of the provided foil is less likely to occur. On the other hand, the upper limit of the surface electrical resistance is, for example, 1.0×10 ¹⁴ Ω, and may be 1.0×10 ¹³ Ω. The surface electrical resistance can be adjusted by ash content or the like. The surface electrical resistance is a value measured in accordance with JIS-K-6911 under an environment of temperature 20° C. and humidity 65% RH.

The compressive strength (longitudinal direction) of the paperboard is preferably 300N or more and 460N or less. Moreover, the compressive strength (lateral direction) of the paperboard is preferably 230N or more and 350N or less. When the compressive strength is within the above range, bending workability, strength, etc. can be enhanced in a well-balanced manner. The compressive strength is a value measured according to JIS-P-8126-2005 “Paper and paperboard—Method for testing compressive strength—Ring crush method”.

The Z-axis strength of the paperboard is preferably 130 mJ or more and 160 mJ or less. When the Z-axis strength is within the above range, foil stamping aptitude, bending workability, strength, etc. can be improved in a well-balanced manner. The Z-axis strength is determined according to JAPAN TAPPI Paper Pulp Test Method No. 18-1:2000.

The paperboard can be suitably used as a paperboard for foil stamping.

<Processed paperboard>
A processed paperboard according to an embodiment of the present invention comprises the paperboard according to an embodiment of the present invention and a foil crimped to a part of the surface side surface of the paperboard. That is, the processed paperboard is a paperboard whose surface has been foil-stamped. The processed paperboard is foil-stamped with little unevenness and has excellent cosmetic properties. The foil, for example in the form of letters, graphics, etc., is laminated to the surface of the paperboard. The foil is usually a metal foil such as an aluminum foil. In the processed paperboard, the foil is generally not laminated on the entire surface of the surface layer side, but the foil is partially laminated, and the surface layer of the paperboard is exposed in other parts. In the processed paperboard, the exposed portion of the surface layer has a suppressed luster, and also from this point, it is excellent in cosmeticity. The processed paperboard can be suitably produced by the production method described below.

The processed paperboard can be used for paper boxes, containers, book covers, business cards, etc., and can be particularly suitably used as a material for paper boxes. The processed paperboard can also be used as a liner for corrugated board.

<Manufacturing method of processed paperboard>
A method for manufacturing a processed paperboard according to an embodiment of the present invention comprises a step of foil-stamping the surface of the paperboard according to an embodiment of the present invention. According to the manufacturing method, it is possible to obtain processed paperboard with foil stamping that has less unevenness and is excellent in cosmeticity.

The manufacturing method is the same as a conventional hot stamping method or the like, except that the paperboard according to one embodiment of the present invention is used as the paper to be foil-stamped. That is, for example, the paperboard is fixed to a jig, and the foil is pressed against the paperboard with a heated plate in a state in which the foil is sandwiched between the paperboard and the plate. The foil for hot stamping is laminated to one side of the film, and the side of the foil opposite the film (the side facing the paperboard surface) is coated with an adhesive. Heat and pressure from the plate releases the foil from the film and transfers it to the paperboard. The heat from the plate melts the adhesive applied to the foil, and the paperboard and foil are adhered by this adhesive. Thus, the heat and pressure from the plate thermocompresses the foil to the paperboard. At this time, when the paperboard of one embodiment of the present invention is used, heat is transferred from the surface layer portion pressed by the plate to the surroundings (the surface layer not pressed by the plate) because the surface layer has high heat insulation and heat retention part), and heating is effectively generated along the shape of the plate. Therefore, the foil is transferred along the shape of the plate with little unevenness, and a highly decorative processed paperboard can be obtained.

The paperboard of the present invention will be described in more detail based on the following examples, but the present invention is not limited to these examples.
Various measurements and evaluations were performed by the following methods.

・Content ratio of mechanical pulp The content ratio of mechanical pulp in the surface layer is obtained by disintegrating the surface layer in accordance with JIS-P-8220-1998. P-8120-1998 "Paper, paperboard and pulp-Fiber composition test method".

Ash content The ash content of the surface layer and the entire paperboard was measured according to JIS-P-8251 "Paper, paperboard and pulp-Ash content test method-525°C combustion method".

・Ash component The ash component of the surface layer was measured by energy dispersive X-ray spectrometry.

Basis weight The basis weight of the paperboard was measured in accordance with the "measurement method for basis weight" described in JIS-P-8124.

・Ten point average roughness (Rz)
The ten-point average roughness (Rz) of the surface on the surface side conforms to JIS-B-0601:1994 "Product Geometric Characteristic Specifications (GPS)-Surface Texture: Contour Method-Terms, Definitions and Surface Texture Parameters". Then, 10 samples were measured using a surface roughness measuring instrument (manufactured by Mitutoyo, product name: SJ-201P), and the average value thereof was taken as the value.

・PPS smoothness The PPS smoothness of the surface on the surface side conforms to Appendix A of JIS-P-8151-2004, manufactured by Lorentzen & Bettley Co., Ltd., model name: SE-115, soft as a backing disk A rubber object was used, and the clamp pressure was set to 1 MPa for the measurement.

• Bekk smoothness The Bekk smoothness of the surface on the surface side was measured according to JIS-P-8119-1998.

·Surface electric resistance The surface electric resistance of the surface on the surface layer side was measured in accordance with JIS-K-6911 under an environment of a temperature of 20°C and a humidity of 65% RH.

· Compressive strength The compressive strength (longitudinal direction and transverse direction) of the paperboard was measured according to JIS-P-8126-2005 "Paper and paperboard - Compressive strength test method - Ring crush method".

・Z-axis strength The Z-axis strength of the paperboard is determined according to JAPAN TAPPI Paper Pulp Test Method No. 18-1:2000.

- Foil stamping suitability Foil stamping was performed using a desktop foil stamping machine (hot stamp) and a transparent hologram foil "Laser Select" manufactured by Kurz Co., Ltd. at a transfer temperature of 130°C for a transfer time of 1 second. The foil stamping aptitude was evaluated according to the following criteria.
⊚: Good foil stamping was obtained without uneven gloss on the foil surface or peeling.
◯: Slight uneven gloss was observed on the surface of the foil, but there was no problem with the cosmetic properties.
Δ: Gloss unevenness was observed on the foil surface.
x: Uneven luster was observed on the foil surface, and partial peeling was observed at the edges.

・Matte (white paper glossiness)
Glossiness of the surface (surface on the surface layer side) was measured according to "Paper and paperboard - measuring method of 75 degree specular glossiness" described in JIS-P-8142-2005. It can be judged that the lower the glossiness is, the more the gloss is sufficiently matted and the gloss is suppressed.

[Example 1]
The main component of the raw material pulp for the surface layer (1 layer) is white paper, the raw material pulp for the intermediate layer (2 to 4 layers) is used, and the raw material pulp for the back layer (5 layers) is used. The paperboard of Example 1 consisting of 5 paper layers and having a basis weight of 170 g/m ² was obtained by a paper machine. As the surface treatment, coating with a surface sizing agent and flattening treatment were not performed.

[Examples 2 to 11, Comparative Examples 1 to 5]
Paperboards of Examples 2 to 11 and Comparative Examples 1 to 5 were obtained in the same manner as in Example 1 except that the raw material pulp type, presence or absence of surface treatment, basis weight and ash content of each layer were as shown in Table 1. . The ash content was adjusted by appropriately adjusting the content of white waste paper contained in the surface layer or by using raw material pulp obtained from different sources. That is, the raw material pulp of the surface layer of Examples 1 to 11 used hollow waste paper as a main component, and other waste paper was appropriately blended.
In Comparative Examples 1, 2 and 5, the surface was coated with 0.08 g/m ² of a surface sizing agent (Hersize KN-275P from Harima Kasei Co., Ltd.) as a surface treatment.

[evaluation]
Mechanical pulp content in the surface layer of each paperboard obtained by the above-described method, basis weight, ten-point average roughness (Rz) of the surface (surface) on the surface layer side, PPS smoothness, Bekk smoothness, surface electrical resistance , surface layer and total board ash, surface layer ash content, compressive strength (machine direction and transverse direction), and Z-axis strength were measured. In addition, each paperboard obtained was evaluated for foil stamping aptitude and matting property by the above-described methods. Table 1 or Table 2 shows the measurement results and evaluation results.

As shown in Tables 1 and 2, each of the paperboards of Examples 1 to 11 having a ten-point average roughness (Rz) of 14 μm or more and 20 μm or less and a PPS smoothness of 6 μm or more and 10 μm or less on the surface side is a foil It has excellent pressability and good mattness.

On the other hand, when looking at the comparative examples, comparative examples 2 and 6, which are subjected to calendering and have extremely high surface smoothness, have suitability for foil stamping, but are insufficient in matting. Other Comparative Examples 1, 3 to 5 have insufficient or too rough surface roughness and poor foil stamping suitability. It can be seen that by making the surface moderately rough such that the surface has a ten-point average roughness (Rz) of 14 μm or more and 20 μm or less and a PPS smoothness of 6 μm or more and 10 μm or less, it is possible to achieve both foil stamping suitability and mattness.

The paperboard of the present invention can be suitably used as a paperboard for foil stamping used for paper boxes and the like.

Claims (5)

A paperboard having a top layer, a back layer, and one or more intermediate layers disposed between the top layer and the back layer,
The paperboard having a ten-point average roughness (Rz) of 14 μm or more and 20 μm or less and a PPS smoothness of 6 μm or more and 10 μm or less on the surface of the surface layer. 2. The paperboard according to claim 1, wherein the surface layer has an ash content of 9% by mass or more and a mechanical pulp content of 50% by mass or more. 3. The paperboard according to claim 1, which is used for foil stamping. A processed paperboard comprising: the paperboard according to claim 3; and a foil crimped to a part of the surface of the paperboard. A method for producing a processed paperboard, comprising the step of foil-stamping the surface of the paperboard according to claim 3.