Packaging paper, package, and method for manufacturing packaging paper

Abstract

To provide: a packaging paper which is capable of obtaining a package including a translucent region excellent in visibility when a content is viewed from the outside, and which is capable of preventing blocking; a method for manufacturing the packaging paper; and a package including the packaging paper.SOLUTION: A packaging paper 1A of the invention includes: a cellulose sheet 2 having a first surface 2a and a second surface 2b different in smoothness; a translucent region 4 where a transparentizing material 3 penetrates from the second surface 2b into the cellulose sheet 2; and a coating layer 5 disposed on a surface of the translucent region 4 which is located on a side of the first surface 2a.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a packaging paper, a package, and a method for manufacturing the packaging paper. [Background technology]

[0002] Packaging such as envelopes and product packages often have a translucent region that allows the addressee and contents to be seen from the outside. While some packaging papers have a transparent resin film, from the viewpoint of resource recycling and the like, packaging papers with a translucent region in which at least a portion of the paper is made transparent are preferred.

[0003] There are several methods for making paper transparent. One of the methods proposed is to impregnate the spaces between the fibers of a cellulose sheet with a transparent resin (for example, Patent Documents 1 to 4). By impregnating the spaces between the cellulose fibers with a transparent resin, it is possible to increase the transparency of the translucent regions impregnated with the transparent resin. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Unexamined Patent Publication No. 132698 / 1983 [Patent Document 2] Japanese Patent Publication No. 132699 / 1983 [Patent Document 3] Japanese Patent Application Publication No. 2018-9047 [Patent Document 4] Patent Publication No. 2021-91481 Summary of the Invention [Problem to be solved by the invention]

[0005] However, simply increasing the transparency of the translucent region by using a transparent resin does not sufficiently improve the visibility of the contents when viewed from outside the package. In addition, the translucent region formed by resin impregnation can exhibit adhesive properties, which can lead to the problem of blocking. The present invention provides a packaging paper and a manufacturing method thereof that can produce a package having a translucent region that provides excellent visibility of the contents when viewed from the outside and prevent blocking; and a package including the packaging paper. [Means for solving the problem]

[0006] The present invention has the following aspects. [1] A wrapping paper comprising: a cellulose sheet having a first surface and a second surface with different smoothness; a translucent region in at least a portion of the cellulose sheet in a planar view, in which a transparent material is impregnated into the cellulose sheet from the second surface; and a coating layer provided on at least a portion of the surface of the translucent region on the first surface side. [2] The packaging paper of [1], wherein the smoothness of the first surface of the cellulose sheet is higher than the smoothness of the second surface of the cellulose sheet. [3] The packaging paper of [1] or [2], wherein, in a cross-sectional view perpendicular to the first surface and the second surface, there is a portion of the cellulose sheet where the transparent material does not reach the first surface. [4] The packaging paper according to any one of [1] to [3], wherein the refractive index of the transparent material and the refractive index of the coating layer are each 1.4 to 1.6. [5] The packaging paper according to any one of [1] to [4], wherein the coating layer contains at least one material selected from the group consisting of a transparent material and an overcoat varnish. [6] The packaging paper according to any one of [1] to [5], further comprising a halftone printed area with a light-absorbing substance attached to at least a part of the translucent area on the first surface side. [7] The packaging paper of [6], wherein at least a portion of the halftone printed area is covered with the coating layer. [8] A package having packaging paper of any of [1] to [7]. [9] A method for producing packaging paper, comprising forming a coating layer on the first surface of a cellulose sheet having a first surface and a second surface with different smoothness, and then impregnating the cellulose sheet with a transparent material from the second surface of the cellulose sheet.

[10] The manufacturing method of [9], wherein a light-absorbing substance is attached to the first surface of the cellulose sheet by halftone printing before the formation of the coating layer.

[11] The manufacturing method of [9], wherein a light-absorbing substance is attached to the surface of the coating layer by halftone printing before the impregnation with the transparent material.

[12] The manufacturing method according to any one of [9] to

[11] , wherein the smoothness of the first surface of the cellulose sheet is higher than the smoothness of the second surface of the cellulose sheet. [Effects of the Invention]

[0007] According to the present invention, a packaging body having a translucent area that provides excellent visibility of the contents when viewed from the outside is obtained, and packaging paper that can prevent blocking and a method for manufacturing the same; and a packaging body equipped with the packaging paper are provided. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a plan view schematically illustrating an example of a packaging sheet. [Figure 2] 2 is a diagram schematically illustrating a cross section of the packaging paper of FIG. 1 taken along line II-II. [Figure 3] FIG. 2 is a plan view schematically illustrating an example of a packaging sheet. [Figure 4] 4 is a diagram schematically showing a cross section of the packaging paper of FIG. 3 taken along line IV-IV. FIG. [Figure 5] FIG. 1 is a schematic diagram showing how light rays travel when contents are viewed from the outside in packaging paper having a transparent resin film. [Figure 6] FIG. 1 is a schematic diagram showing that conventional semi-transparent paper does not provide sufficient visibility. [Figure 7] 10A and 10B are schematic diagrams illustrating a possible mechanism by which visibility is improved by a halftone printed portion. [Figure 8] FIG. 2 is a plan view schematically illustrating an example of a packaging sheet. [Figure 9] 9 is a diagram schematically showing a cross section of the packaging paper of FIG. 8 taken along line IX-IX. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present inventors have conducted various studies to improve the visibility of semitransparent regions in which a cellulose sheet is impregnated with a transparent material such as a resin. As a result, it has been discovered that diffuse reflection of light from the unevenness of the surface of the semitransparent region is the cause of impaired visibility. For example, if part of the resin impregnated into the cellulose sheet seeps out from the surface of the cellulose sheet, unevenness will form on the surface of the semitransparent region. Therefore, the inventors came up with the idea of ​​providing a coating layer on at least a portion of the surface of the translucent region to reduce diffuse reflection of light due to surface irregularities in the translucent region. This coating layer increases the surface smoothness of the translucent region, prevents diffuse reflection of light on the surface of the translucent region, and improves the visibility of the translucent region. In addition, because this coating layer is provided on at least a portion of the translucent region, it can also prevent blocking of the packaging paper.

[0010] Below, several examples of packaging paper will be explained with reference to the drawings as appropriate. The dimensional ratios in the drawings are for the sake of convenience and may differ from the actual ones. In the following drawings, the same components are indicated by the same reference numerals, and explanations of overlapping components may be omitted. In addition, in this specification, the use of "to" indicating a range of values ​​means that the values ​​before and after it are included as the lower and upper limits.

[0011] First Embodiment 1 and 2 are schematic diagrams illustrating a packaging paper 1A according to a first embodiment. The packaging paper 1A includes a cellulose sheet 2 having a first surface 2a and a second surface 2b with different smoothnesses; a translucent region 4 in a partial area of ​​the cellulose sheet 2 in a plan view, where a transparent material 3 has been impregnated into the cellulose sheet 2 from the second surface 2b; and a coating layer 5 provided on the surface of the translucent region 4 on the first surface 2a side.

[0012] (cellulose sheet) The cellulose sheet 2 is a sheet whose main component is cellulose fiber. "Whose main component is cellulose fiber" means that the cellulose fiber content is 50% by mass or more of the entire sheet. The cellulose fiber content is preferably 60% by mass or more of the entire sheet, more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and most preferably 100% by mass.

[0013] The cellulose sheet 2 has a first surface 2a and a second surface 2b that have different smoothness. In the packaging paper 1A, the smoothness of the first surface 2a of the cellulose sheet 2 is higher than that of the second surface 2b. As in this example, providing a coating layer 5 on the surface of the translucent region 4 on the first surface 2a side, which has a relatively high smoothness, makes it easier to further increase the smoothness of the surface of the translucent region.

[0014] The smoothness of the first surface 2a is preferably 10 seconds or more, more preferably 30 to 2000 seconds, and even more preferably 30 to 1000 seconds. When the smoothness of the first surface 2a is at least the lower limit of the above-mentioned numerical range, excellent visibility is likely to be obtained in the translucent region 4. When the smoothness of the first surface 2a is at most the upper limit of the above-mentioned numerical range, it is easy to obtain a cellulose sheet 2 suitable for producing packaging paper 1A. The smoothness of the second surface 2b is preferably less than 1000 sec, more preferably 20 to 1000 sec, and even more preferably 20 to 300 sec. When the smoothness of the second surface 2b is at least the lower limit of the above-mentioned numerical range, excellent visibility is likely to be obtained in the translucent region 4. When the smoothness of the second surface 2b is at most the upper limit of the above-mentioned numerical range, it is easy to obtain a cellulose sheet 2 suitable for producing packaging paper 1A. The smoothness of each of the first surface 2a and the second surface 2b is measured in accordance with JAPAN TAPPI Paper and Pulp Testing Method No. 5-2 and JIS P8155.

[0015] Examples of the cellulose sheet 2 include a paper substrate, a paperboard, and a nonwoven fabric. Among these, a paper substrate is preferred because excellent visibility in the translucent region 4 can be easily obtained. The main component of the pulp contained in the paper base material is cellulose fiber. Examples of pulp include chemical pulp, mechanical pulp, cotton, hemp, recycled paper pulp, non-wood pulp, etc. However, the pulp in the paper base material is not limited to these examples.

[0016] Examples of chemical pulp include softwood-derived pulp (NKP) and hardwood-derived pulp (LKP). Examples of pulp derived from softwood include unbleached softwood kraft pulp (NUKP), bleached softwood kraft pulp (NBKP), semi-bleached softwood kraft pulp (NSBKP), and softwood sulfite pulp (NSP). Examples of hardwood-derived pulp include unbleached hardwood kraft pulp (LUKP), bleached hardwood kraft pulp (LBKP), semi-bleached hardwood kraft pulp (LSBKP), and hardwood sulfite pulp (LSP).

[0017] Examples of mechanical pulp include stone ground pulp (SGP), pressurized stone ground pulp (PGW), refiner ground pulp (RGP), thermoground pulp (TGP), chemiground pulp (CGP), groundwood pulp (GP), and thermomechanical pulp (TMP).

[0018] Examples of waste paper pulp include disintegrated waste paper pulp, disintegrated and deinked waste paper pulp, and disintegrated, deinked, and bleached waste paper pulp. Examples of waste paper that can be used as a raw material for waste paper pulp include brown paper, kraft envelope paper, magazine paper, newspaper paper, flyer paper, office paper, cardboard paper, white paper, Kent paper, imitation paper, and land certificate paper. Non-wood pulp includes various pulps such as pulp produced chemically or mechanically from non-wood fibers such as kenaf, cotton, hemp, and reed.

[0019] Among these, chemical pulp is suitable for achieving both visibility and strength in the packaging paper 1A, and therefore it is preferable that chemical pulp be the main component of the cellulose sheet 2. Furthermore, one type of pulp may be used alone, or two or more types may be used in combination.

[0020] When recycled paper pulp is used as the pulp, the recycled paper pulp content is preferably 10% by mass or less, more preferably 5% by mass or less, based on the total mass of pulp in the paper base material. When the recycled paper pulp content is equal to or less than the upper limit, the packaging paper 1A can be suitably used for packaging food and beverages. The lower limit of the recycled paper pulp content is 0% by mass.

[0021] To improve smoothness, whiteness, etc., the paper base material may contain fillers such as talc and calcium carbonate. However, fillers can affect the transparency and visibility of the translucent region 4. Therefore, the filler content is preferably within a range that does not impair visibility, and it is more preferable that the paper base material does not contain fillers.

[0022] Examples of paper substrates include kraft paper, one-sided glossy kraft paper, one-sided glossy paper, fine paper, electrophotographic paper, inkjet recording paper, thermal transfer recording paper, art paper, coated paper, cast-coated paper, white paperboard, colored paperboard, and cardboard liners. Among these, fine paper, electrophotographic paper, kraft paper, one-sided glossy kraft paper, and one-sided glossy paper are preferred, with one-sided glossy kraft paper and one-sided glossy paper being more preferred, because they have a low pigment content and tend to provide excellent visibility in the translucent region 4. In one-sided glossy kraft paper and one-sided glossy paper, the glossy side, which has a relatively high smoothness, can be used as the first side, and the non-glossy side, which has a relatively low smoothness, can be used as the second side.

[0023] The freeness of the pulp in the paper base material is preferably 350 ml CSF or more, more preferably 400 to 700 ml CSF, and even more preferably 450 to 600 ml CSF. When the freeness of the pulp in the paper base material is equal to or greater than the lower limit of the above-mentioned range, it is easy to maintain the strength of the packaging paper 1A. When the freeness of the pulp in the paper base material is equal to or less than the upper limit of the above-mentioned range, it is easy to obtain packaging paper 1A having a translucent region with excellent transparency and visibility. The freeness (unit: mlCSF) of pulp in the paper base material is measured according to JIS 8121-2.

[0024] Glassine paper, a commonly known translucent paper, has traditionally used highly beaten chemical pulp, for example, chemical pulp with a freeness of 250 ml CSF or less. However, because the highly beaten pulp fibers are ground and cut, they are not suitable for applications such as packaging bags, which require strength, even if they are used for transparent envelope windows. In contrast, in the case of packaging paper 1A, visibility can be ensured even if the freeness of the paper base material is kept at 350 ml CSF or more, making it easier to maintain the strength of packaging paper 1A. Furthermore, even paper base materials such as glassine paper can be used as the cellulose sheet 2 of packaging paper 1A as long as they are within a range that allows the strength of the package to be maintained.

[0025] The basis weight of the paper substrate is preferably 40 to 150 g / cm2, more preferably 45 to 100 g / cm2, and even more preferably 50 to 85 g / cm2. When the basis weight of the paper substrate is equal to or greater than the lower limit of the above-mentioned range, good paper strength as packaging paper is likely to be obtained. When the basis weight of the paper substrate is equal to or less than the upper limit of the above-mentioned range, the opacity of the translucent region 4 is likely to be reduced. The basis weight of the paper substrate is measured according to JIS P8124.

[0026] The density of the paper substrate is preferably 0.5 to 0.8 g / cm3, and more preferably 0.55 to 0.75 g / cm3. When the density of the paper substrate is equal to or greater than the lower limit of the above-mentioned range, the strength of the packaging paper 1A is easily increased. When the density of the paper substrate is equal to or less than the upper limit of the above-mentioned range, the amount of transparent material 3 impregnated is easily increased. The density of the paper substrate is measured according to JIS P8118.

[0027] The porosity of the paper substrate is preferably 30 to 80%, more preferably 40 to 70%, and even more preferably 50 to 70%. When the porosity of the paper substrate is equal to or greater than the lower limit of the above-mentioned range, it is easy to increase the transparency of the translucent region 4. When the porosity of the paper substrate is equal to or less than the upper limit of the above-mentioned range, it is easy to maintain the relatively high smoothness of the first surface 2a during manufacturing. The porosity of the paper substrate is calculated by dividing the density measured according to JIS P8118 by the true density of cellulose, 1.50.

[0028] The thickness of the paper base material is preferably 20 to 120 μm, more preferably 20 to 80 μm, and even more preferably 30 to 70 μm. When the thickness of the paper base material is at least the lower limit of the above numerical range, the strength of the packaging paper 1A is easily increased. When the thickness of the paper base material is at most the upper limit of the above numerical range, excellent visibility in the translucent region 4 is easily obtained. The thickness of the paper substrate is measured according to JIS P8118.

[0029] The method for producing the paper base material is not particularly limited, and examples thereof include a method including a step of beating pulp, which is the raw material for the paper base material, a step of making a pulp slurry containing the beaten pulp, and a step of drying the wet sheet obtained by papermaking. In the beating step, it is preferable to beat the raw pulp until the disintegration freeness of the paper base material reaches a desired range. The beating machine is not particularly limited. For example, a double disc refiner or the like can be used.

[0030] There are no particular limitations on the paper machine used for papermaking, and examples thereof include a Fourdrinier paper machine, a short wire paper machine, and a cylinder paper machine. After papermaking, the surface of the paper substrate obtained through the drying process may be subjected to a smoothing treatment. Smoothing treatment can improve surface strength, printability, etc. An example of a smoothing treatment is a method in which the paper substrate is pressurized between pressure-capable reels. The device for smoothing treatment is not particularly limited. For example, the paper is passed through a machine calender, gloss calender, soft nip calender, etc. before the winder section to perform product finishing. A machine calender and a super calender may be used together, or a super calender may be used instead of a machine calender.

[0031] (semi-transparent area) As shown in Figure 1, the translucent region 4 is formed in a partial area in a plan view of the cellulose sheet 2. When the packaging paper 1A is used as a package, the contents and address can be seen through the translucent region 4 from outside the package. The shape and area ratio of the translucent region 4 in plan view are not limited in any way. They can be set or changed as appropriate depending on the application of the wrapping paper or packaging material. In another example, the translucent region may be the entire area in the planar direction of the cellulose sheet. The number of translucent regions is not particularly limited, and may be one or more. In the case of wrapping paper with multiple translucent regions, the size and shape of each translucent region are not particularly limited.

[0032] As shown in Figure 2, in the translucent region 4, the transparent material 3 is impregnated into the cellulose sheet 2 from the second surface 2b. Here, in the packaging paper 1A, the smoothness of the first surface 2a is higher than that of the second surface 2b. Because the transparent material 3 is impregnated into the cellulose sheet 2 from the second surface 2b, which has lower smoothness, the transparent material 3 penetrates deep into the interior of the cellulose sheet 2. Furthermore, the relatively high smoothness of the first surface 2a is likely to be maintained.

[0033] In the packaging paper 1A, the transparent material 3 may reach the first surface 2a within the cellulose sheet 2. However, as shown in FIG. 2, for example, it is preferable that the transparent material 3 does not reach the first surface 2a in the packaging paper 1A in some portions of the cellulose sheet 2. In the portions of the cellulose sheet 2 where the transparent material 3 does not reach the first surface 2a, the surface condition of the first surface 2a, which has a relatively high degree of smoothness, is likely to remain the same as it was before the transparent material 3 was impregnated. In addition, irregularities are unlikely to form on the surface of the translucent region 4 on the first surface 2a side. This is thought to further suppress diffuse reflection of light and further improve the visibility of the translucent region 4.

[0034] There are no particular limitations on the transparentizing material 3. Examples of the transparentizing material 3 include transparentizing resins such as acrylic resin, polyethylene resin, polyester resin, urethane resin, nitrocellulose, shellac, and rosin; vegetable oils such as tung oil, linseed oil, castor oil, hydrophilic castor oil, coconut oil, soybean oil, and commercially available salad oil; and waxes such as carnauba wax, palm wax, beeswax, spermaceti, and Japan wax. The transparentizing material 3 may be used alone or in combination of two or more kinds.

[0035] Among them, a transparentizing resin that is stable over time is preferable, and an acrylic resin is more preferable. Among the acrylic resins, an ultraviolet-curable acrylic resin is particularly preferable because it has excellent surface coating properties and makes the interface of the region impregnated with the transparentizing material 3 clear in cross-sectional view. Examples of ultraviolet-curable acrylic resins include those disclosed in paragraphs 0025 and 0026 of JP 2021-91481 A.

[0036] It is preferable to select the transparent material 3 from the above examples, one having a refractive index in the range of 1.4 to 1.6, preferably 1.45 to 1.58, more preferably 1.50 to 1.58, and even more preferably 1.52 to 1.58. This is because the refractive index of cellulose fibers is generally said to be in the range of 1.4 to 1.6. When the refractive index of the transparent material 3 is within this range, the difference with the refractive index of the cellulose fibers is small, making it easy to improve the transparency and visibility of the translucent region 4. The refractive index of the transparentizing material 3 is measured in accordance with JIS K 7142.

[0037] By impregnating the cellulose fibers with a transparent material 3 having a refractive index close to that of the cellulose fibers and filling the gaps between the cellulose fibers, it is possible to reduce the refraction of light caused by the transparent material 3 in the cellulose sheet 2. This makes it easier to obtain a translucent region 4 with excellent transparency and visibility. To adjust the refractive index, high refractive index substances such as zirconium and titanium may be used as needed.

[0038] Since the clarifying material 3 is to be impregnated into the cellulose fibers, it is preferably a liquid at room temperature or in a heated state. Furthermore, a material that can be dissolved in a liquid medium such as an organic solvent at room temperature or in a heated state is also preferable in terms of permeability. That is, the clarifying material 3 is preferably a material that can be impregnated into the cellulose sheet 2 as a permeable liquid clarifying agent during production. The clarifying agent will be described later. The translucent regions 4 in the cellulose sheet 2 primarily comprise the clarifying material 3, although other components may be present that originate from the clarifying agent used during manufacture.

[0039] The opacity of the semitransparent region 4 is preferably 4 to 25%, more preferably 4 to 20%, and even more preferably 4 to 15%. When the opacity of the semitransparent region 4 is equal to or greater than the lower limit of the above-mentioned range, the strength of the packaging paper made of the cellulose sheet 2 is easily increased. When the opacity of the semitransparent region 4 is equal to or less than the upper limit of the above-mentioned range, the transparency of the semitransparent region 4 is improved. The opacity of the semi-transparent area is measured according to JIS P 8138:1976.

[0040] The haze of the semitransparent region 4 is preferably 80% or less. When the haze of the semitransparent region 4 is 80% or less, the transparency of the semitransparent region 4 is improved. The lower limit of the haze of the semitransparent region 4 is not particularly limited, but is, for example, 10% or more, preferably 20% or more. When the haze of the semitransparent region 4 is the lower limit or more, the strength of the packaging paper is easily increased. The haze of the semi-transparent region 4 is measured in accordance with JIS-K7136.

[0041] The density of the translucent region 4 is preferably 0.7 to 2.5 g / cm3, more preferably 0.7 to 2.0 g / cm3, and even more preferably 0.8 to 2.0 g / cm3. When the density of the translucent region 4 is equal to or greater than the lower limit of the above-mentioned range, it is believed that the air spaces between the fibers are sufficiently eliminated by impregnation with the resin component. When the density of the translucent region is equal to or less than the upper limit of the above-mentioned range, the processability of the packaging paper 1A when it is made into a package or the like is improved. The density of the semi-transparent region 4 is measured in accordance with JIS P 8118.

[0042] (coating layer) The coating layer 5 is provided on the surface of the cellulose sheet 2 on the first surface 2a side of the translucent region 4. The coating layer 5 is intended to increase the smoothness of the surface of the translucent region 4. The packaging paper 1A has a coating layer 5, which increases the smoothness of the surface, prevents diffuse reflection of light on the surface of the translucent region 4, and improves the visibility of the translucent region 4. Furthermore, the coating layer 5 allows some of the material of the coating layer to penetrate near the surface of the first side 2a of the cellulose sheet 2, filling voids in the cellulose sheet 2 and thereby increasing transparency. In addition, since the coating layer 5 is provided on the surface of the translucent region 4 impregnated with the transparent material 3, it is also possible to prevent blocking of the packaging paper 1A.

[0043] The prevention of blocking by the coating layer 5 will now be described. For example, as shown in Figure 2, we will explain how to prevent blocking when there is a portion of the cellulose sheet 2 where the clarifying material 3 does not reach the first surface 2a. In this case, if the coating layer 5 were not present, for example, when multiple pieces of packaging paper 1A were stacked and stored, the second surface 2b impregnated with the clarifying material 3 would overlap with the first surface 2a not impregnated with the clarifying material 3. As a result, the cellulose fibers on the first surface 2a would stick to the resin component of the clarifying material 3 on the second surface 2b, potentially causing blocking. In packaging paper 1A, the coating layer 5 can prevent such blocking.

[0044] This section explains how to prevent blocking when the transparent material 3 reaches the first surface 2a within the cellulose sheet 2. In this case, if the coating layer 5 is not present, blocking may occur, for example, when multiple pieces of packaging paper 1A are stacked and stored while the transparent material 3 near the first surface 2a is not sufficiently dried. In the case of packaging paper 1A, the coating layer 5 can prevent such blocking even when the transparent material 3 reaches the first surface 2a within the cellulose sheet 2.

[0045] 1 and 2, i.e., in packaging paper 1A, coating layer 5 is provided over the entire surface of translucent region 4 in the planar direction, but in other examples, the coating layer may be provided over only a portion of the translucent region in the planar direction. In addition, the number of coating layers may be one or more.

[0046] The material of the coating layer 5 is preferably a transparent material from the viewpoint of visibility. Examples of the material of the coating layer 5 include a transparent material and OP varnish. Examples of the transparent material include the same materials as those exemplified in the section on the translucent region. When the coating layer 5 contains a transparent material, the transparent material of the coating layer 5 and the transparent material 3 of the translucent region 4 may be the same or different. Furthermore, the material of the coating layer 5 may be used alone or in combination of two or more types.

[0047] OP varnish is sometimes called overprint varnish. The components of OP varnish vary depending on the product, manufacturer, etc., but OP varnish containing at least one selected from the group consisting of linseed oil, tung oil, and soluble nitrocellulose is preferred. Commercially available OP varnishes include products from Toyo Ink Co., Ltd., T&K TOKA Corporation, and Fuji Ink Mfg. Co., Ltd. One type of OP varnish may be used alone, or two or more types may be used in combination. Drying methods such as oxidative polymerization and UV irradiation may be used.

[0048] It is preferable to select a material for the coating layer 5 from among these, one having a refractive index in the range of 1.4 to 1.6, preferably 1.45 to 1.60, more preferably 1.48 to 1.60, even more preferably 1.50 to 1.60, and particularly preferably 1.50 to 1.58. This is because the refractive index of cellulose fibers is generally said to be in the range of 1.4 to 1.6. By adjusting the refractive index of the coating layer 5 to a value close to the refractive index of the cellulose fibers, it is possible to reduce the refraction of light at the interface between the coating layer 5 and the cellulose sheet 2. This makes it easier to obtain a translucent region 4 with excellent visibility. The refractive index of the coating layer 5 is measured in accordance with JIS K 7142.

[0049] The smoothness of the coating layer 5 is preferably 50 to 1000 seconds, more preferably 50 to 500 seconds, and even more preferably 100 to 500 seconds. When the smoothness of the coating layer 5 is within the above range, visibility is likely to be further improved. The smoothness of the coating layer 5 is measured in accordance with JAPAN TAPPI Paper and Pulp Test Method No. 5-2 and JIS P8155.

[0050] The thickness of the coating layer 5 is preferably 0.5 to 2.5 μm, more preferably 0.5 to 2.0 μm, and even more preferably 0.7 to 2.0 μm. When the thickness of the coating layer 5 is at least the lower limit of the above-mentioned range, the surface has a glossy appearance, and excellent visibility is likely to be obtained in the translucent region 4. When the thickness of the coating layer 5 is at most the upper limit of the above-mentioned range, unevenness and curling of the paper sheet due to differences in shrinkage after drying between the coated and uncoated areas are suppressed. The thickness of the coating layer 5 is the maximum thickness measured when a cross section perpendicular to the plane is cut out and observed under an electron microscope.

[0051] (Manufacturing method of packaging paper 1A) The packaging paper 1A can be produced, for example, by the following method (1). Method (1): A manufacturing method in which a coating layer 5 is formed on the first surface 2a of a cellulose sheet 2 having a first surface 2a and a second surface 2b, and then a transparent material 3 is impregnated into the cellulose sheet 2 from the second surface 2b of the cellulose sheet 2.

[0052] In forming the coating layer 5, a coating liquid containing the material for the coating layer 5 is applied to the first surface 2a of the cellulose sheet 2. Then, if necessary, it is dried to provide the coating layer 5 on the first surface 2a.

[0053] When the material of the coating layer 5 is solid at room temperature, a coating liquid is prepared using a liquid medium capable of dissolving the material of the coating layer 5. When the material of the coating layer 5 is liquid at room temperature, the concentration of the coating liquid may be changed using a liquid medium, or the coating liquid may be used as is without using a liquid medium. Details of the liquid medium will be described later.

[0054] The method for applying the coating liquid containing the material for the coating layer 5 is not particularly limited. Examples include various coating methods such as roll coating, bar coating, blade coating, dip coating, flexographic printing, gravure printing, offset printing, gravure offset printing, and silk screen printing. Furthermore, the drying method, if any, is also not particularly limited. Natural drying or heat drying may be used.

[0055] In the impregnation of the transparentizing material 3, a liquid transparentizing agent is applied to the second surface 2b of the cellulose sheet 2. The transparentizing agent is a liquid containing the transparentizing material. When the transparentizing material is solid at room temperature, a liquid medium capable of dissolving the transparentizing material is used to prepare the liquid transparentizing agent. When the transparentizing material is liquid at room temperature, the concentration of the transparentizing material may be changed using a liquid medium, or the transparentizing material may be used as is as the transparentizing agent without using a liquid medium.

[0056] The liquid medium is not particularly limited. Either an aqueous solvent or an organic solvent can be used. If the liquid medium contains water, the cellulose sheet 2 is likely to swell due to the water. Furthermore, the cellulose sheet 2 is likely to shrink during subsequent drying. This can lead to curling, lumps, and unevenness. Therefore, it is preferable that the liquid medium does not contain water, and an organic solvent is more preferable.

[0057] The organic solvent may be a polar solvent or a non-polar solvent. Examples of polar solvents include alcohols, ethers, esters, and non-polar solvents. Examples of alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, n-pentanol, and n-hexanol. Examples of ethers include ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol monoethyl ether, ethylene glycol monopropyl ether, diethylene glycol monopropyl ether, triethylene glycol monopropyl ether, tetraethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monoisopropyl ether, triethylene glycol monoisopropyl ether, tetraethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, diethylene glycol monoisobutyl ether, triethylene glycol glycol monoisobutyl ether, tetraethylene glycol monoisobutyl ether, ethylene glycol monotertiary butyl ether, diethylene glycol monotertiary butyl ether, triethylene glycol monotertiary butyl ether, tetraethylene glycol monotertiary butyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monoethyl ether, tetrapropylene glycol monoethyl ether, propylene glycol monopropyl ether, dipropylene glycol monopropyl ether, tripropylene glycol monopropyl ether, propylene glycol monoisopropyl ether, dipropylene glycol monoisopropyl ether, tripropylene glycol monoisopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, propylene glycol monoisobutyl ether,Examples of glycol ethers include dipropylene glycol monoisobutyl ether, tripropylene glycol monoisobutyl ether, propylene glycol monotertiary butyl ether, dipropylene glycol monotertiary butyl ether, and tripropylene glycol monotertiary butyl ether. Examples of the esters include diethylene glycol monoethyl ether acetate and diethylene glycol monobutyl ether acetate. Examples of non-polar solvents include paraffinic hydrocarbons such as pentane, hexane, heptane, octane, nonane, decane, and dodecane; isoparaffinic hydrocarbons such as isohexane, isooctane, and isododecane; alkylnaphthenic hydrocarbons such as liquid paraffin; aromatic hydrocarbons such as benzene, toluene, xylene, alkylbenzene, and solvent naphtha; and silicone oil.

[0058] The clarifying agent may further contain other components in addition to the clarifying material and the liquid medium. Examples of the other components include basic substances such as ammonia, ethylenediamine, and triethylamine; viscosity modifiers such as glycerin and ethylene glycol; high refractive index substances such as zirconium and titanium; antifoaming agents; and mold release agents. However, the other components are not limited to these examples.

[0059] The coating amount of the clarifying agent per unit area is preferably 10 to 70 g / m2, more preferably 20 to 60 g / m2, and even more preferably 30 to 60 g / m2. When the coating amount of the clarifying agent per unit area is equal to or greater than the lower limit of the above-mentioned range, the transparency of the translucent region 4 is easily increased. When the coating amount of the clarifying agent per unit area is equal to or less than the upper limit of the above-mentioned range, the clarifying agent is less likely to reach a part of the inside of the first surface 2a.

[0060] The viscosity of the clarifying agent is preferably 50 to 5000 mPa·s, more preferably 50 to 4000 mPa·s, and even more preferably 50 to 3000 mPa·s. If the viscosity of the clarifying agent is equal to or greater than the upper limit of the above-mentioned range, the clarifying agent will be less likely to reach a portion of the inside of the first surface 2a. If the viscosity of the clarifying agent is equal to or less than the upper limit of the above-mentioned range, the clarifying agent will be more likely to penetrate into the cellulose sheet 2. The viscosity of the clarifying agent is measured using a Brookfield viscometer at 30° C. and 60 rpm.

[0061] The method for applying the clarifying agent is not particularly limited, and examples of the method for applying the clarifying agent include flexographic printing, inkjet printing, gravure printing, offset printing, gravure offset printing, silk screen printing, roll coating, bar coating, and blade coating.

[0062] After application of the clarifying agent, the temperature may be increased in a drying oven to reduce the viscosity of the clarifying agent in order to promote impregnation of the clarifying material. The drying temperature, drying time, and drying method are not particularly limited and may be appropriately changed taking productivity and production costs into consideration. For example, hot air at a temperature of 50 to 120°C may be used and the drying time may be 2.0 to 30 seconds.

[0063] By impregnating the cellulose sheet 2 with a clarifying agent, the voids between the fibers in the cellulose sheet 2 can be filled with the clarifying material 3. When a clarifying agent containing a clarifying material with a refractive index in the range of 1.4 to 1.6 is used, the voids in the cellulose sheet 2 can be filled with the clarifying agent whose refractive index is close to that of cellulose. This makes it possible to reduce the refraction of light caused by the clarifying material 3 in the cellulose sheet 2.

[0064] The application and impregnation of the clarifying agent into the cellulose sheet 2 may be carried out in one step or in multiple steps. When the application and impregnation are carried out in multiple steps, the constituent components and composition of the clarifying agent used in each step may be the same or different from each other.

[0065] When an ultraviolet-curable clarifying agent is used, various light sources can be used, such as a high-pressure mercury lamp, a metal halide lamp, a xenon lamp, and an electrodeless discharge lamp. The integrated light amount is not particularly limited and can be appropriately changed depending on the amount of clarifying agent used and the type of clarifying resin.

[0066] In the method (1) described above, before the cellulose sheet 2 is impregnated with the clarifying material 3, a coating layer 5 is formed on the first surface 2a of the cellulose sheet 2. Therefore, when the clarifying agent is impregnated into the cellulose sheet 2 from the second surface 2b of the cellulose sheet 2, the coating layer 5 can prevent the clarifying agent from seeping out from the cellulose sheet 2 to the first surface 2a. Therefore, according to the method (1), unevenness is less likely to occur on the surface of the translucent region 4 on the first surface 2a side. Therefore, the coating layer 5 reliably prevents diffuse reflection of light on the surface of the translucent region 4 on the first surface 2a side, improving the visibility of the translucent region 4. Also, since the clarifying agent is prevented from seeping out of the cellulose sheet 2 onto the first surface 2a, contamination of the manufacturing equipment can be suppressed. Additionally, the coating layer 5 prevents blocking when the packaging paper 1A is wound or stacked.

[0067] Additionally, the smoothness of the first surface 2a of the cellulose sheet 2 is higher than that of the second surface 2b. Therefore, the density of cellulose fibers is higher closer to the second surface 2a within the cellulose sheet 2. Therefore, the clarifying material 3 can easily penetrate into the cellulose sheet 2 from the second surface 2b. In this way, in method (1), the transparentizing material 3 is impregnated into the cellulose sheet 2 from the second surface 2b, which is more easily impregnated. Therefore, the semi-transparent region 4 is easily formed, and there is an advantage in that productivity is excellent.

[0068] In method (1), as shown in Fig. 2, when the transparentizing agent is impregnated, it is preferable to form a portion in the cross section of the cellulose sheet 2 where the transparentizing material 3 does not reach part of the first surface 2a. This is because the surface state of the first surface 2a, which has a relatively high degree of smoothness, is likely to be maintained in the state it was in before the transparentizing material 3 was impregnated. As a result, irregularities are unlikely to form on the surface of the translucent region 4 on the first surface 2a side, which makes it easier to further improve the visibility of the translucent region 4. For example, by appropriately changing the viscosity, drying speed, hardening speed, etc. of the clarifying agent, it is possible to prevent the clarifying material 3 from reaching a part of the inside of the first surface 2a.

[0069] (Mechanism of action of the first embodiment) In the packaging paper 1A described above, the coating layer 5 can prevent diffuse reflection of light on the surface of the translucent region 4. Therefore, packaging paper 1A can provide a package having a translucent region that provides excellent visibility of the contents when viewed from the outside. Furthermore, the coating layer 5 is provided on the surface of the first surface 2a of the translucent region 4, in which the transparent material 3 is impregnated into the cellulose sheet 2 from the second surface 2b side. Therefore, the coating layer 5 can prevent blocking on the first surface 2a side.

[0070] In order to fill the gaps between the fibers in the cellulose sheet 2 with the clarifying material 3, it is preferable to increase the amount of the clarifying material 3 impregnated as much as possible. However, in conventional methods that do not form a coating layer 5, if the amount of the clarifying material 3 impregnated and used is increased, the clarifying material 3 will seep out of the cellulose sheet 2 onto the first surface 2a, increasing the risk of creating irregularities on the surface of the translucent region 4. In addition, blocking is likely to occur when the paper is wound or stacked. In contrast, packaging paper 1A can be manufactured by the above-mentioned method (1). Forming coating layer 5 before impregnation with clarifying material 3 as in method (1) reduces the risk of the clarifying material 3 impregnated into cellulose sheet 2 seeping out from first surface 2b to first surface 2a. This allows the amount of clarifying material 3 impregnated and used to be as large as possible, making it easier to increase the transparency of the surface of translucent region 4. Furthermore, coating layer 5 can prevent blocking of packaging paper 1A.

[0071] 1 used in the above explanation is a schematic diagram, and therefore the boundary between the cellulose sheet 2 and the semi-transparent region 4 in plan view and the boundary between the cellulose sheet 2 and the coating layer 5 in plan view do not necessarily exist as clearly as shown in FIG. 2 is also a schematic diagram. In principle, the interface between the cellulose sheet 2 and the transparentizing material 3 in a cross-sectional view, and the interface between the cellulose sheet 2 and the coating layer 5 in a cross-sectional view, can be observed using an electron microscope. However, these interfaces in a cross-sectional view may not be clearly present or may be difficult to clearly identify, as shown schematically in FIG. 2.

[0072] <Second embodiment> 3 and 4 are schematic diagrams illustrating a packaging paper 1B according to an example of the second embodiment. In addition to the cellulose sheet 2, the translucent region 4, and the coating layer 5, the packaging paper 1B further includes a halftone printed area 6B on the first surface 2a of the translucent region 4, to which a light-absorbing substance 7 is attached. The details and preferred embodiments of the cellulose sheet 2, the translucent region 4, and the coating layer 5 in the packaging paper 1B can be basically the same as those described for the packaging paper 1A.

[0073] The halftone printed portion 6B has a plurality of dots of light-absorbing material 7 deposited thereon by halftone printing. In other words, the halftone printed portion 6B is a collection of a plurality of dots of light-absorbing material 7. The shape of the dot pattern of the halftone printed portion 6B is not particularly limited. Examples include halftone dots, grids, diagonal lines, circles, rings, and polygons, but the shape is not limited to these examples. The shape of the dot pattern can be changed as appropriate depending on the settings for halftone printing.

[0074] The light-absorbing material 7 in each dot of the halftone printed portion 6B has the function of absorbing light scattered within the cellulose sheet 2. Therefore, although the amount of light transmitted through the cellulose sheet 2 is reduced, scattered light in the translucent region 4 on the first surface 2a side is suppressed. In this way, the packaging paper 1B has the halftone printed area 6B, which can absorb the scattered light generated within the cellulose sheet 2. As a result, the visibility of the contents in the translucent area 4 is further improved.

[0075] The halftone printed area 6B is formed by adhering a plurality of dots of a light-absorbing substance 7 to the surface of the first surface 2a of the cellulose sheet 2. The halftone printed area 6B is covered with a coating layer 5. Therefore, packaging paper 1B including the halftone printed portion 6B is likely to prevent diffuse reflection of light on the outermost surface on the first surface 2a side of translucent region 4. As a result, combined with the effect of absorbing scattered light by halftone printed portion 6B, it is believed that the visibility of the contents in translucent region 4 is further improved.

[0076] The size of each dot in the halftone printed portion 6B is not particularly limited. For example, it is preferably 40 to 100 μm, and more preferably 50 to 80 μm. When the dot size is equal to or greater than the lower limit of the above-mentioned range, the halftone printed portion 6B is likely to absorb scattered light. When the dot size is equal to or less than the upper limit of the above-mentioned range, it is believed that the halftone printed portion 6B is unlikely to affect the color tone or color impression of the translucent region 4. The dot size is measured as the diameter or minor axis of the circumscribing circle or ellipse that contains the smallest area of ​​a single dot. The dot size can be changed as needed by changing the settings for halftone printing.

[0077] The area ratio of the halftone printed portion 6B is preferably 20 to 80%, more preferably 25 to 75%. When the area ratio is equal to or greater than the lower limit of the above-mentioned range, the halftone printed portion 6B is likely to absorb scattered light. When the area ratio is equal to or less than the upper limit of the above-mentioned range, it is thought that the halftone printed portion 6B is unlikely to affect the color tone or color impression of the translucent region 4. The area ratio of a halftone print is the area of ​​dots per unit area expressed as a percentage. In the case of solid printing, the area ratio is 100%, and if there are no dots, the area ratio is 0%. The area ratio can be changed as needed by changing the settings when performing halftone printing.

[0078] The light-absorbing material 7 is not particularly limited as long as it has a high absorption coefficient. Since the light-absorbing material 7 is formed by halftone printing, the ink used for printing can be prepared and used. For example, black components, particularly black inks, are preferred because of their excellent light absorption properties. The black ink may be a single black ink or a composite black ink that combines multiple colors. However, the color of the light-absorbing material 7 is not limited to black.

[0079] The color of the light-absorbing substance 7 is preferably changed as appropriate depending on the use of the packaging paper 1B, the contents when the packaging is completed, the color of the cellulose sheet, and the color of the contents. This is because, for example, visibility and color can be changed to suit the preferences of users and consumers. In commercialization, for example, a light-absorbing substance of a color similar to the color of the contents of the packaging may be used, or a light-absorbing substance of a color complementary to the color of the contents of the packaging may be used. It is also preferable to change the shape of the dot pattern of the halftone printed portion 6B, the size of each dot, and the area ratio as appropriate depending on the use of the wrapping paper, the contents of the wrapping, and the color of the contents, because this allows the visibility and color to be adjusted to suit the preferences of users and consumers.

[0080] 3 and 4, packaging paper 1B has a halftone printed portion 6B in which light-absorbing substance 7 is adhered to almost the entire surface in the planar direction of semi-transparent region 4 on first surface 2a, but in other examples, the halftone printed portion may be formed by adhering light-absorbing substance 7 to part of semi-transparent region 4 on first surface 2a. Even when light-absorbing substance 7 is adhered to at least part of semi-transparent region 4 on first surface 2a, the effect of absorbing scattered light by the halftone printed portion can be obtained.

[0081] In the packaging paper 1B, the entire halftone-printed portion 6B is covered with the coating layer 5, but in other examples, only part of the halftone-printed portion may be covered with the coating layer 5. Even when only part of the halftone-printed portion is covered with the coating layer 5, the effect of preventing diffuse reflection of light by the coating layer 5 can be obtained.

[0082] (Manufacturing method of packaging paper 1B) The method for producing the packaging paper 1B may be, for example, the following method (2). Method (2): A manufacturing method in which, in the method (1) described in the first embodiment, a light-absorbing material 7 is attached to the first surface 2a of the cellulose sheet 2 by halftone printing before the coating layer 5 is formed.

[0083] By attaching the light-absorbing substance 7 to the first surface 2a of the cellulose sheet 2 by halftone printing, the halftone printed portion 6B can be formed on the first surface 2a of the cellulose sheet 2. By forming the halftone printed portion 6B on the first surface 2a before forming the coating layer 5, the halftone printed portion 6B can be covered by the coating layer 5.

[0084] The method of halftone printing is not particularly limited. Various printing methods can be used. Examples include offset printing, gravure printing, flexographic printing, screen printing, inkjet printing, and electrophotographic printing. Furthermore, halftone printing may be performed using the same printer as that used for applying and impregnating the clarifying agent, or may be performed using a separate printer.

[0085] Method (2) is the same as method (1) except that the cross-hatched printed portion 6B is formed before the formation of the coating layer 5. The details and preferred embodiments of the formation of the coating layer 5 and the impregnation of the clarifying agent can be the same as those described for method (1).

[0086] (Mechanism of action of the second embodiment) The packaging paper 1B described above has the cellulose sheet 2, the translucent region 4, and the coating layer 5, and therefore has the same effects as the packaging paper 1A. This results in a package with a translucent region that provides excellent visibility of the contents from the outside. In addition, the coating layer prevents blocking. In addition, the packaging paper 1B has a halftone printed portion 6B, which can absorb scattered light in the translucent region 4. As a result, a package having a translucent region that provides even better visibility of the contents when viewed from the outside is obtained.

[0087] 4 used to explain the packaging paper 1B is a schematic diagram. The halftone-printed portion 6B is formed by applying multiple dots of the light-absorbing material 7 by halftone printing. Therefore, in a cross-sectional view, the interface between the cellulose sheet 2 and the light-absorbing material 7 (halftone-printed portion 6B) and the interface between the coating layer 5 and the light-absorbing material 7 (halftone-printed portion 6B) may not necessarily be clearly present, as shown schematically in FIG. 4.

[0088] The mechanism by which visibility is improved by the halftone printed portion 6B will be explained using Figures 5 to 7. In Figures 5 to 7, a transparent resin film F (Figure 5), semi-transparent paper 21 (Figure 6), and packaging paper 1B (Figure 7) are layered on top of a package 10 having an object image 11 printed on its upper surface. The arrows indicate the direction of light reflected from the object image 11 when the object image 11 printed on the package 10 is perceived as a visual image 12. In Figure 5, a transparent resin film F is placed on top of the package 10. In the case of the transparent resin film F, the light rays reflected from the object image 11 travel in a straight line toward the visual position, i.e., the position of the visual image, so the outline of the visual image 12A is clear. Therefore, the information of the object image 11 can be clearly seen through the resin film F. In Figure 6, conventional translucent paper 21 is placed on top of package 10. In the case of translucent paper 21, light reflected from object image 11 is refracted by resin 23 impregnated in cellulose sheet 22, and much of the light is scattered. As a result, visual image 12B of object image 11 is unclear and has a fuzzy outline. It is difficult to say that it has sufficient visibility. In Figure 7, packaging paper 1B is placed on top of package 10. The halftone printed area 6B absorbs scattered light generated within cellulose sheet 2. As a result, of the light rays reflected from object image 11, those that travel in a straight line toward the visual position tend to selectively pass through translucent area 4. Therefore, the contours of visual image 12C are clearer than those of visual image 12B. In this way, the information on object image 11 can be clearly seen through the film, and it is thought that visibility is improved.

[0089] <Third embodiment> 8 and 9 are schematic diagrams illustrating a packaging paper 1C according to an example of the third embodiment. In addition to the cellulose sheet 2, the translucent region 4, and the coating layer 5, the packaging paper 1C further includes a halftone printed area 6C on the first surface 2a of the translucent region 4, on which a light-absorbing substance 7 is adhered.

[0090] Packaging paper 1C differs from packaging paper 1B in that the halftone-printed portion 6C is not covered with a coating layer 5. Other than this, the details and preferred aspects of halftone-printed portion 6C are the same as those described for halftone-printed portion 6B. In the packaging paper 1C, the halftone printed portion 6C is formed by adhering a plurality of dots of light absorbing material 7 to the surface of the coating layer 5.

[0091] In the packaging paper 1C, the halftone-printed area 6C can also absorb scattered light generated within the cellulose sheet 2. Furthermore, because the halftone-printed area 6C is made up of multiple dots of light-absorbing material 7 attached by halftone printing, it is less likely to impair the smoothness of the surface of the coating layer 5. Therefore, the semi-transparent area 4 of the packaging paper 1C can also absorb scattered light and prevent diffuse reflection on the surface. This allows for excellent visibility of the contents in the semi-transparent area 4.

[0092] (Manufacturing method of packaging paper 1C) As a method for producing the packaging paper 1C, for example, the following method (3) can be mentioned. Method (3): A manufacturing method in which, in the method (1) described in the first embodiment, a light-absorbing substance 7 is attached to the surface of the coating layer 5 by halftone printing before the transparent material 3 is impregnated.

[0093] By attaching the light-absorbing substance 7 to the surface of the coating layer 5 by halftone printing, a halftone-printed area 6C can be formed on the surface of the coating layer 5. As shown in packaging paper 1C as an example, even if a halftone-printed area is formed on the surface of the coating layer before impregnation with the transparent material, it is possible to produce packaging paper having a halftone-printed area in which the light-absorbing substance is attached in the translucent region on the first surface side of the cellulose sheet.

[0094] Method (3) is the same as method (1) except that a cross-hatched printed portion 6C is formed on the surface of the coating layer 5 before the impregnation with the clarifying material 3. The details and preferred aspects of the formation of the coating layer 5 and the impregnation with the clarifying agent can be the same as those described for method (1). In addition, the details and preferred aspects of the cross-hatched printing can be the same as those described for method (2).

[0095] (Mechanism of action of the third embodiment) The packaging paper 1C described above has the cellulose sheet 2, the translucent region 4, and the coating layer 5, and therefore achieves the same effects as the packaging paper 1A. This results in a package with a translucent region that provides excellent visibility of the contents from the outside. The coating layer also prevents blocking. Additionally, the packaging paper 1C has a halftone printed area 6C, which can absorb scattered light in the translucent area 4. As a result, a package having a translucent area that provides even better visibility of the contents when viewed from the outside is obtained.

[0096] 9 used to explain packaging paper 1C is a schematic diagram. Also, halftone-printed portion 6C is formed by applying multiple dots of light-absorbing material 7 by halftone printing. Therefore, the interface between coating layer 5 and light-absorbing material 7 (halftone-printed portion 6C) in a cross-sectional view may not necessarily be clearly defined, as is shown schematically in FIG.

[0097] <Application> The wrapping paper is suitable for use in packaging, such as envelopes and packages for various products. For example, wrapping paper can be shaped into a bag to be used as a packaging bag. The translucent area of ​​the wrapping paper can be used as a window to check the contents of the packaging bag. To use the wrapping paper as a packaging bag, the wrapping paper can be bonded using various adhesives, heat sealing agents, etc. and processed into a bag shape. The shape of the packaging bag is not particularly limited. Examples include envelopes, flat bags, square-bottom bags, gusseted bags, and carrier bags. The shape may be selected appropriately depending on the contents.

[0098] Although several examples of one embodiment have been described above, the present invention is not limited to the embodiments disclosed in this specification and can be appropriately modified and implemented without departing from the spirit of the invention. The embodiments disclosed in this specification can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. [Example]

[0099] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following description.

[0100] <Raw materials> (cellulose sheet) In the following examples, one-sided glossy kraft paper (1) with a basis weight of 50 g / m2 was used. The glossy side of the one-sided glossy kraft paper (1) had a smoothness of 120 sec, and the non-glossy side had a smoothness of 10 sec. The density of the one-sided glossy kraft paper (1) was 0.75 g / cm3, the thickness was 67 μm, and the porosity was 50%.

[0101] (clarifying agent) Clarifying agent (1): An acrylic paraffin solvent (trade name: Clariten DC, manufactured by Yamato Chemical Industry Co., Ltd.) was prepared as a clarifying material. The refractive index of this clarifying material was 1.50. An aromatic paraffin-based solvent (product name: Clariten S, manufactured by Yamato Chemical Industry Co., Ltd.) was prepared as the solvent. These clarifying materials and the solvent were mixed to prepare a clarifying agent (1) with a clarifying material concentration of 75% by mass. The viscosity of the clarifying agent (1) at 30°C and 60 rpm was 1000 mPa s.

[0102] (coating layer) DC AB OP varnish OJ3 (manufactured by DIC Graphics Corporation) was used as the OP varnish (1) used to form the coating layer.

[0103] (light-absorbing material) Black ink (trade name: NCP Matte Ink, manufactured by DIC Graphics) was used.

[0104] Example 1 Using a Matsuo Sangyo micrometer-adjustable applicator, coating liquid (1) was applied to the glossy side of one-side gloss kraft paper (1). It was then dried for 30 seconds in a hot air dryer at 120°C, forming a 1.0 μm-thick coating layer (smoothness: 130 sec) on the glossy side of the one-side gloss kraft paper (1). Next, using a Matsuo Sangyo micrometer-adjustable applicator, clarifying agent (1) was applied to the non-glossy side of the one-side gloss kraft paper (1) in an amount of 35 g / m². This was then cured with ultraviolet light using an NPT-453 (4.8 kW, two lamps) manufactured by Nippon Bunka Seiko Co., Ltd., to obtain the packaging paper of Example 1.

[0105] <Example 2> The packaging paper of Example 2 was obtained in the same manner as Example 1, except that before forming the coating layer, halftone printing was performed with black ink on the glossy side of the one-sided glossy kraft paper (1). The area ratio of the halftone printing was 25%, the dot size was 50 μm, and the shape of each dot was circular.

[0106] <Comparative Example 1> The packaging paper of Comparative Example 1 was obtained in the same manner as in Example 1, except that no coating layer was formed.

[0107] <Evaluation and measurement methods> (Visibility) An A4-sized printed matter with a 10.5-point Word document printed on it was placed on a horizontal table, and each example's wrapping paper was placed on top of it. Visibility was evaluated based on the following criteria, with the printed matter being readable through the semi-transparent area of ​​the wrapping paper from a position 30 cm above. ◎: Characters are recognizable with no missing characters. ○: Some characters are missing, but the characters can be recognized. ×: Characters are missing in multiple places, making them difficult to read. ××: Characters are missing in many places, making them extremely difficult to recognize.

[0108] (Opacity of transparent areas) Measurements were made using a Suga Test Instruments color meter SC-WT in accordance with JIS P8149.

[0109] <Result> The results are shown in Table 1.

[0110] [Table 1]

[0111] As shown in Table 1, the packaging papers of Examples 1 and 2 had better visibility than the packaging paper of Comparative Example 1. Furthermore, the packaging paper of Example 2, which was subjected to halftone printing, had improved visibility compared to the packaging paper of Example 1. [Industrial Applicability]

[0112] According to the present invention, a packaging body having a translucent area that provides excellent visibility of the contents when viewed from the outside is obtained, and packaging paper that can prevent blocking and a method for manufacturing the same; and a packaging body equipped with the packaging paper are provided. [Explanation of symbols]

[0113] 1 (1A, 1B, 1C)...packaging paper, 2...cellulose sheet, 3...transparent material, 4...semi-transparent area, 5...coating layer, 6 (6B, 6C)...shaded printed area, 7...light-absorbing material, 10...packaging, 11...target image, 12...visible image, F...resin film.

Claims

1. a cellulose sheet having a first surface and a second surface with different smoothness; a translucent region in which a transparency material is impregnated into the cellulose sheet from the second surface in at least a partial region in a plan view of the cellulose sheet; a coating layer provided on at least a portion of the surface of the translucent region on the first surface side; The wrapping paper comprises:

2. The wrapping paper of claim 1 , wherein the first surface of the cellulose sheet has a smoothness greater than the smoothness of the second surface of the cellulose sheet.

3. The wrapping paper according to claim 1 or 2, wherein, in a cross-sectional view perpendicular to the first surface and the second surface, there is a portion of the cellulose sheet where the transparent material does not reach the first surface.

4. The wrapping paper according to any one of claims 1 to 3, wherein the refractive index of the transparent material and the refractive index of the coating layer are each 1.4 to 1.

6.

5. The packaging paper according to any one of claims 1 to 4, wherein the coating layer comprises at least one material selected from the group consisting of a clarifying material and an OP varnish.

6. The packaging paper according to any one of claims 1 to 5, further comprising a halftone printed section in which a light-absorbing substance is attached to at least a part of the translucent region on the first surface side.

7. The wrapping paper according to claim 6 , wherein at least a portion of the halftone printed area is covered with the coating layer.

8. A packaging body comprising the packaging paper according to any one of claims 1 to 7.

9. A method for producing packaging paper, comprising forming a coating layer on a first surface of a cellulose sheet having a first surface and a second surface with different smoothness, and then impregnating the cellulose sheet with a transparent material from the second surface of the cellulose sheet.

10. The method of claim 9 , wherein a light-absorbing material is applied to the first surface of the cellulose sheet by halftone printing before the formation of the coating layer.

11. The method of claim 9 , wherein a light-absorbing substance is attached to the surface of the coating layer by halftone printing before the impregnation with the transparentizing material.

12. The manufacturing method according to any one of claims 9 to 11, wherein the smoothness of the first surface of the cellulose sheet is higher than the smoothness of the second surface of the cellulose sheet.

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