JP7526580B2 - Packaging for paper products - Google Patents

Description

The present invention relates to a packaging material for paper products that is suitable for packaging paper products, particularly paper products such as tissue paper.

Conventionally, packages are known that contain rolled paper products such as toilet paper and kitchen paper, and layered paper products such as tissue paper and wipes as packaged items.

For example, Patent Document 1 discloses a package for wrapping rolled paper products, in which a gusset is folded symmetrically into a cylindrical film such as polyethylene to form a main body, and the top of the main body is folded flat to form a handle.

On the other hand, paper cartons made of high-weight paperboard are commonly used as packaging for layered paper products. As an alternative to paper cartons, for example, Patent Document 2 discloses a film packaging body in which a perforation is provided in the center of the top surface of a packaging bag made of a flexible resin film.

JP 2004-269010 A JP 2016-188092 A

However, there has been a demand for new packaging that uses the above-mentioned paper products, particularly paper products such as tissue paper, as the packaged items. In particular, due to the growing awareness of environmental issues in recent years, there is a desire to reduce the use of plastics (synthetic resins), and even in paper packaging, there is a desire to reduce the amount of packaging materials used, but this has been difficult to achieve when using paper products, particularly soft paper products such as tissue paper, as the packaged items.

Although paper cartons formed by bonding together sheets of rigid paper have existed, the shape of the seal that provides good adhesion and is suitable for use as a packaging base material for packaging paper products has not been identified.

The present invention was made in consideration of these circumstances, and its purpose is to provide a package for paper products that has good adhesion at the seal even when the packaged item is a paper product, particularly a paper product such as tissue paper.

In view of the above problems, the inventors of the present invention have conducted extensive research and have found that by specifying the basis weight of the packaging base material and providing at least two recesses of a predetermined circumferential length in the seal portion such that the ends of the recesses are adjacent to each other at a constant distance, a paper product package having good adhesion in the seal portion can be obtained even when a paper product, particularly a paper product such as tissue paper, is packaged, thereby solving the above problems and completing the present invention.
Specifically, the present invention provides the following:

(1) A first aspect of the present invention is a package for paper products, in which one or more paper products are entirely covered with a packaging base material, and the paper products are sealed by at least one seal portion, wherein the packaging base material includes at least a paper base material and a seal layer, the basis weight of the packaging base material is 35 g/ ^m2 or more and 105 g/ ^m2 or less, the seal portion is provided at an end where the packaging base materials overlap, and the seal portion has at least two or more recesses with a circumference of 0.6 mm or more and 16 mm or less, and the ends of each recess are adjacent to each other with a distance of 0.2 mm or more and 6 mm or less between them.
(2) A second aspect of the present invention is the packaging material for paper products described in (1), characterized in that the depth of the recess is 0.05 mm or more and 0.49 mm or less.
(3) A third aspect of the present invention is a packaging body for paper products described in (1) or (2), characterized in that the pitch of the recess in a direction perpendicular to the longitudinal direction of the seal portion is 0.3 mm or more and 5.9 mm or less.
(4) A fourth aspect of the present invention is a packaging body for paper products according to (2) or (3), characterized in that (depth of the recess/basis weight of the packaging base material) x 100 is 0.07 or more and 1.5 or less.
(5) A fifth aspect of the present invention is a packaging body for paper products described in any one of (1) to (4), characterized in that the bending stiffness of the packaging base material in the MD direction is 20 μN·m or more and 330 μN·m or less.
(6) A sixth aspect of the present invention is a packaging body for paper products described in any one of (1) to (5), characterized in that the bending stiffness of the packaging base material in the CD direction is 8 μN·m or more and 145 μN·m or less.
(7) A seventh aspect of the present invention is a packaging material for paper products according to any one of (1) to (6), characterized in that the sealing layer is a heat sealing layer and/or an adhesive layer.
(8) An eighth aspect of the present invention is the packaging material for paper products according to (7), characterized in that the heat seal layer contains a polyolefin resin.
(9) A ninth aspect of the present invention is a packaging body for paper products according to any one of (1) to (8), characterized in that the paper product is tissue paper.
(10) A tenth aspect of the present invention is the packaging material for paper products according to (9), characterized in that the tissue paper is a laminated tissue paper.
(11) An eleventh aspect of the present invention is a packaging body for paper products according to any one of (1) to (10), characterized in that the packaging body is a gusset package or a pillow package.

The present invention provides a package for paper products that has good adhesiveness at the seal, even when the packaged item is a paper product, particularly a paper product such as tissue paper.

1 is a perspective view showing an example of a packaging body for paper products and a paper product of the present invention. 4 is a diagram illustrating a method for measuring the depth and pitch of recesses in the seal portion of the packaging body for paper products of the present invention. FIG.

The following describes in detail the form for carrying out the present invention (hereinafter, "embodiment") with reference to the drawings. However, these are presented for illustrative purposes and are not intended to limit the present invention.

1. Packaging for paper products FIG. 1 is a perspective view showing an example of a packaging for paper products (hereinafter, also simply referred to as "packaging") of the present invention and a paper product. In the packaging 1 of the present invention, a paper product (packaged item) 11 is entirely covered with a packaging substrate 10, and the paper product 11 is sealed by at least one sealed portion 12. The sealed portion 12 is provided at the end where the packaging substrates 10 overlap, and the sealed portion 12 has at least two recesses 13 with a circumferential length of 0.6 mm to 16 mm, and the ends of the recesses 13 are adjacent to each other at a distance of 0.2 mm to 6 mm. At this time, as shown in FIG. 1, it is preferable that the sealed portion 12 is formed in a substantially straight line at both ends of the packaging 1, and that the sealed portions 12 are formed substantially parallel to each other, but as long as the sealing property of the packaging 1 (the adhesiveness of the sealed portion 12) can be ensured, the sealed portions 12 may be formed at other locations or may have different shapes, and three or more sealed portions 12 may be provided (not shown). In addition, in the package 1, the packaging base material 10 may cover only a portion of the paper product 11 rather than the entirety of the paper product 11, and the paper product 11 does not have to be sealed (not shown).
The distance between the ends of each recess 13 is preferably 0.4 mm or more and 4 mm or less, and more preferably 0.6 mm or more and 2 mm or less.

With regard to the recesses 13 of the seal portion 12, it is preferable that the recesses 13 are arranged in a lattice pattern (i.e., the approximately rectangular portions of the lattice pattern correspond to the recesses 13) as shown in Fig. 1. By arranging the recesses 13 in a lattice pattern, it is possible to improve the adhesiveness of the seal portion 12 of the package 1. Even if the recesses 13 are arranged in a lattice pattern, they do not necessarily need to be arranged in parallel in the longitudinal direction of the seal portion 12, and may be arranged alternately like dots, for example.
The perimeter of the recess 13 is preferably 1 mm or more and 10 mm or less, and more preferably 2 mm or more and 6 mm or less. The shape of the recess 13 is preferably a substantially square as shown in Fig. 1, but may be a substantially rectangular, substantially circular, substantially oval, or the like.

In this case, in order to improve the adhesiveness of the seal portion 12, it is preferable that the seal portion 12 has 20 to 2000 recesses 13 in total, more preferably 100 to 1400 recesses, and even more preferably 200 to 800 recesses. In addition, in a direction perpendicular to the longitudinal direction of the seal portion 12, it is preferable that the recesses 13 are arranged in a number of rows of 2 to 20, more preferably 3 to 15, and even more preferably 4 to 10. When counting the number of recesses 13 arranged in a direction perpendicular to the longitudinal direction of the seal portion 12, even if there is no recess 13 adjacent to a certain recess 13 in that direction as viewed from the certain recess 13, if another recess 13 exists within 45° from that direction, the other recess 13 can be counted as the number of recesses arranged in the direction perpendicular to the longitudinal direction of the seal portion 12. If multiple seal parts 12 are provided in the package 1, any one of them may have a recess 13. However, to improve the adhesion of the seal parts 12, it is preferable that all of the seal parts 12 have a recess 13, as shown in FIG. 1.

It is preferable that the package 1 has an opening for removing the paper product 11 (not shown). This opening is preferably provided by forming a tear line, such as a perforation, in the packaging base material 10 so that the package can be opened by cutting along the tear line when in use.

The depth of the recess 13 is preferably 0.05 mm or more and 0.49 mm or less, more preferably 0.1 mm or more and 0.4 mm or less, and even more preferably 0.15 mm or more and 0.3 mm or less. If the depth of the recess 13 is less than 0.05 mm, the adhesiveness may be weak when the seal portion 12 is provided on the packaging substrate 10. If the depth of the recess 13 exceeds 0.49 mm, the adhesiveness may be too strong when the seal portion 12 is provided on the packaging substrate 10, and the packaging substrate 10 may be easily burned. By setting the depth of the recess 13 within the above numerical range, the adhesiveness of the seal portion 12 of the packaging body 1 can be improved.

In addition, the pitch of the recesses 13 in the direction perpendicular to the longitudinal direction of the seal portion 12 is preferably 0.3 mm or more and 5.9 mm or less, more preferably 0.6 mm or more and 4.5 mm or less, and even more preferably 1 mm or more and 3 mm or less. If the pitch of the recesses 13 is less than 0.3 mm, the depth of the recesses 13 becomes shallow, and the adhesiveness of the seal portion 12 may be weakened. If the pitch of the recesses 13 exceeds 5.9 mm, the adhesiveness of the seal portion 12 will be weakened if wrinkles are formed in the seal portion 12 in the direction perpendicular to the longitudinal direction of the seal portion 12. By setting the pitch of the recesses 13 within the above numerical range, the adhesiveness of the seal portion 12 of the package 1 can be improved.
In addition, the pitch of the recesses 13 in the direction perpendicular to the longitudinal direction is large, that is, when the length of the seal portion 12 in the direction perpendicular to the longitudinal direction (width direction) is constant, the number of recesses 13 arranged in the width direction is small. If the number of recesses 13 is large, even if there is a recess 13 with weak adhesiveness, it can be compensated for by the adjacent recesses 13, but if the number of recesses 13 is small, there are no adjacent recesses 13, so it cannot be compensated for, leading to weakened adhesiveness of the seal portion 12. Here, the width direction length of the seal portion 12 is preferably 2 mm or more and 35 mm or less, more preferably 4 mm or more and 24 mm or less, and even more preferably 6 mm or more and 13 mm or less. By setting the width direction length of the seal portion 12 within the above numerical range, the adhesiveness of the seal portion 12 of the package 1 can be improved.

The pitch of the recesses 13 may vary depending on the position of the seal portion 12. Specifically, in addition to the seal portions 12 at both ends of the package 1 shown in Fig. 1, further seal portions may be formed (not shown) that connect approximately the center portions of the seal portions 12 and are perpendicular to each of the seal portions 12. In this case, the pitch of the recesses 13 in the seal portions 12 at both ends is preferably larger than the pitch of the recesses 13 in the seal portions perpendicular to the seal portions.
This is because, when forming the seal portion 12 as described above, the basic procedure is to first form the orthogonal seal portions, and then form the seal portions 12 at both ends. However, in the case of gusset packaging, which will be described later, the seal portions 12 at both ends are partially layered in four layers, making them thicker, and therefore in order to bond these parts, it is necessary to bond them more firmly than the orthogonal seal portions.

A method for measuring the depth and pitch of the recesses 13 will be described below.
The depth and pitch of the recesses 13 are measured using a microscope. As the microscope, a product name "One Shot 3D Measuring Microscope VR-3100" manufactured by Keyence Corporation can be used. As the observation, measurement, and image analysis software for the microscope image, a product name "VR-H1A" manufactured by Keyence Corporation can be used. The measurement conditions are a magnification of 38 times and a field area of 8 mm x 6 mm. The measurement magnification and field area may be appropriately changed depending on the desired size of the recesses 13.
Furthermore, when the package 1 has a front and back (when the package 1 has an opening for removal), the measurement surface of the sealed portion 12 is the front side of the package 1. When a sealed portion perpendicular to the sealed portions 12 at both ends is formed as described above, the measurement point is the point where one of the sealed portions 12 at both ends overlaps with the perpendicular sealed portion to form a four-ply stack. In other embodiments, that is, when the relevant point is not a four-ply stack, if the sealed portion 12 is partially four-ply stacked due to gusset packaging as described below, the four-ply stack point is measured, and when the entire package is only two-ply stacked, the two-ply stack point is measured.

First, a two-dimensional unevenness image of the XY plane of the above-mentioned field of view is obtained using a microscope, as shown in Fig. 2(a). In the unevenness image, it can be seen that the height of the seal portion 12 is represented by light and dark shades.
Next, when an operator draws a line in the width direction across multiple recesses 13 lined up along the longitudinal direction of the seal portion 12 (preferably arranged in a grid pattern in the seal portion 12), a (measured) cross-sectional curve (cross-sectional profile) showing the unevenness is obtained as shown in Fig. 2(b), and the pitch and depth of the recesses 13 in the width direction of the seal portion 12 are measured. Note that if there are no recesses adjacent to the recess 13 to be measured in the width direction, a line is drawn at an angle of 45° or less from the width direction of the recess 13, and the pitch between the recesses and the closest recess on the line is determined.
Here, the (measured) cross-sectional curve in FIG. 2(b) is a (measured) cross-sectional curve that represents the unevenness of the surface of the seal portion 12, but it also contains noise (sharp peaks due to fiber clumps, whisker-like fibers, fiber-free areas, etc. on the surface of the seal portion 12). When calculating the depth and pitch of the recesses 13, it is necessary to remove such noise peaks.

Therefore, using the above analysis software, the (measured) profile curve in FIG. 2(b) is smoothed with the filter size of the weighted average radio button set to ±12 to obtain the profile curve after noise is removed, as shown in FIG. 2(c).
Then, in the graph shown in FIG. 2(c), the average value of the maximum heights on the vertical axis of the convex portion of the graph and the convex portion adjacent to the convex portion is calculated. In addition, the minimum value of the height on the vertical axis of the concave portion sandwiched between these two convex portions is obtained. The value obtained by subtracting the minimum value from the average value of the maximum values thus obtained is set as the depth D1 of the concave portion 13. In addition, the pitch P1 is obtained from the difference in the horizontal axis between the concave portion of the graph and the concave portion adjacent to the concave portion. When the above-mentioned measurements are performed on three consecutive convex portions and two concave portions sandwiched between them on the cross-sectional curve shown in FIG. 2(c), measurement results of the depths of a total of two concave portions 13 are obtained.
When there are two consecutive protrusions and only one recess between them, it is sufficient to measure the depth of one recess 13. When there are four or more consecutive protrusions and three or more recesses between them, multiple measurements may be taken.

2. Packaging Substrate The packaging substrate 10 includes at least a paper substrate and a seal layer. When the paper substrate is formed into the packaging body 1, printing may be applied to the outer surface side. The paper substrate may be an overcoated paper that is overcoated to ensure waterproofing.

The basis weight of the packaging substrate 10 (for example, the total basis weight of the paper substrate and the seal layer) is 35 g/m ² or more and 105 g/m ² or less, preferably 40 g/m ² or more and 85 g/m ² or less, and more preferably 50 g/m ² or more and 75 g/m ² or less. If the basis weight of the packaging substrate 10 is less than 35 g/m ² , when the sealing portion 12 is provided on the packaging substrate 10, the strength of the packaging substrate 10 is too low and it is easily broken when bending it into an appropriate shape, and the sealing portion 12 cannot be neatly bonded. If the basis weight of the packaging substrate 10 exceeds 105 g/m ² , the strength of the packaging substrate 10 is too high and it is difficult to bend it into an appropriate shape, and the sealing portion 12 cannot be neatly bonded. By setting the basis weight of the packaging substrate 10 within the above numerical range, the adhesion of the sealing portion 12 of the package 1 can be made good.

In addition, when the basis weight of the packaging substrate 10 is A and the depth of the recess 13 in the above-mentioned sealed portion 12 is B, (B/A) x 100 is preferably 0.07 to 1.5, more preferably 0.2 to 0.6, and even more preferably 0.26 to 0.5. By setting the ratio of the depth B of the recess 13 to the basis weight A of the packaging substrate 10 within the above numerical range, the adhesiveness of the sealed portion 12 of the package 1 can be improved.

(1) Paper Base The paper base is produced using wood pulp as the main raw material. The pulp used here may be any of the conventionally known pulps, such as softwood kraft pulp, hardwood kraft pulp, groundwood pulp, thermomechanical pulp, chemi-thermomechanical pulp, and recycled paper pulp used in newspapers, flyers, rough magazines, coated magazines, thermal recording paper, pressure-sensitive recording paper, imitation paper, colored wood-free paper, copy paper, computer output paper, or a mixture of these recycled paper, either alone or in any mixture ratio.

In the paper base material of the packaging body 1 of the present invention, the pulp content is preferably 50-100% by weight softwood kraft pulp and 0-50% by weight hardwood kraft pulp, more preferably 70-100% by weight softwood kraft pulp and 0-30% by weight hardwood kraft pulp, and even more preferably 90-100% by weight softwood kraft pulp and 0-10% by weight hardwood kraft pulp. By using the above pulp contents, the adhesiveness of the seal portion 12 of the packaging body 1 can be improved. Also, unbleached pulp is preferable.

The pulp slurry may contain materials other than pulp fiber as secondary materials. In the packaging body 1, the pulp fiber content is usually preferably 70% by weight or more and 100% by weight or less, more preferably 80% by weight or more and 100% by weight or less, and even more preferably 90% by weight or more and 100% by weight or less. By setting the pulp content at the above levels, the adhesiveness of the seal portion 12 of the packaging body 1 can be improved. In addition, the strength of the packaging base material 10 becomes appropriate, making packaging easier.

The cooking and bleaching methods used in pulp production are not particularly limited.

In addition, various commonly used additives, such as wet strength agents, fillers, sizing agents, dry strength agents, retention agents, color pigments, etc., may be added to the paper base material in appropriate amounts as needed.

The wet strength improver can be selected from among those commonly used and known. For example, it is preferable to select from polyamide-polyamine resins, polyacrylamide resins, melamine resins, etc. The content of such wet strength improver (mass in an absolute dry state) is usually 0.01% by weight to 0.7% by weight, preferably 0.02% by weight to 0.5% by weight, more preferably 0.03% by weight to 0.3% by weight, relative to the pulp (mass in an absolute dry state). If the content of the wet strength improver exceeds 0.7% by weight, it is difficult to obtain an effect commensurate with the content, resulting in an increase in costs and a decrease in disintegration property, which may make it difficult to reuse the packaging body 1 of the present invention later. If the content of the wet strength improver is less than 0.01% by weight, it is difficult to obtain sufficient wet strength, and the packaging body may be easily torn when wet with water, resulting in poor functionality.

In the packaging body 1 of the present invention, these raw materials can be made into paper using a normal papermaking process to obtain the paper base material for the packaging base material 10.

The basis weight of the paper base material of the packaging base material 10 is preferably 25 g/m ² or more and 88 g/m ² or less, more preferably 30 g/m ² or more and 72 g/m ² or less, and even more preferably 40 g/m ² or more and 56 g/m ² or less. When the basis weight of the paper base material is within the above range, the adhesiveness of the seal portion 12 of the package 1 can be improved. In addition, it becomes easier to achieve all of the required flexibility, softness, and strength of the packaging base material while suppressing the amount of paper base material used.

The basis weight of the paper base material can be determined, for example, as follows when the seal layer is a heat seal layer described below.
First, prepare a 0.1 M acetic acid solution and a 0.1 M sodium acetate solution. Mix about 830 g of the 0.1 M acetic acid solution and about 160 g of the 0.1 M sodium acetate solution to make the pH 4, and use this as an acetate buffer solution. Add cellulase Onozuka P1500 (manufactured by Yakult Pharmaceutical Co., Ltd.) to this acetate buffer solution so that the amount added is 1 wt%.
50 ml of acetate buffer containing cellulase Onozuka p1500 and 0.5 g of packaging substrate 10 (paper substrate with heat seal layer) are placed in a vial and tightly capped. Next, after shaking for 24 hours at 180 rpm and 40°C, the heat seal layer is sampled from the vial and the mass of the heat seal layer portion is measured. The basis weight of the paper substrate is calculated from the mass (0.5 g) of the packaging substrate 10 (paper substrate with heat seal layer) and the mass of the sampled heat seal layer according to the following formula.
Basis weight of paper base material =
Basis weight of packaging substrate 10 × [(mass of packaging substrate 10 − mass of heat seal layer) / mass of packaging substrate 10]

The ratio of the basis weight of the paper base material to the basis weight of the packaging base material 10 (e.g., the total basis weight of the paper base material and the seal layer) may be 51% or more and 100% or less, but is usually more preferably 60% or more and 95% or less, and even more preferably 70% or more and 90% or less. By keeping it within the above range, the adhesiveness of the seal portion 12 of the package 1 can be improved. It can also ensure ease of packaging for soft paper products 11, and also ensure good heat sealability or adhesiveness.

(2) Seal Layer In the package 1 of the present invention, the packaging substrate 10 includes a seal layer in addition to the paper substrate, and the seal layer is preferably a heat seal layer and/or an adhesive layer. The packaging substrate 10 of the present invention can have a layer structure such as paper substrate/heat seal layer, paper substrate/adhesive layer, paper substrate/heat seal layer/adhesive layer, paper substrate/adhesive layer/heat seal layer, etc.

(2-1) Heat seal layer In the packaging body 1 of the present invention, the heat seal layer may be formed on the entire surface of the paper base material, or may be formed only on a part of the surface, for example, on the part where the paper base materials are laminated and joined together. The position, size, and proportion of the heat seal layer on the surface of the paper base material can be appropriately set.

The material constituting the heat seal layer is not particularly limited, and any of various materials exhibiting heat sealability can be used, such as polyolefin resins and other thermoplastic resins. Among these, it is preferable to use polyolefin resins. Examples of such materials include low-density polyethylene, linear low-density polyethylene, high-density polyethylene, ethylene-α-olefin copolymers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-ethyl acrylate copolymers, ethylene-methyl acrylate copolymers, ethylene-methacrylic acid copolymers, ionomers, amorphous polyesters, polypropylene, styrene-acrylic copolymers, propylene-ethylene copolymers (preferably copolymers with an ethylene content of 10 mol% or less), polypropylene-based resins obtained by graft-polymerizing or copolymerizing unsaturated carboxylic acids, unsaturated carboxylic anhydrides, ester monomers, etc. with polypropylene, and medium-density polyethylene. The materials constituting the heat seal layer may be used alone or in combination of two or more.

The heat seal layer can be formed by a commonly used method, for example, a method of forming a film of a thermoplastic resin such as a polyolefin resin or a composition containing a thermoplastic resin on a paper substrate by an extrusion method, a method of attaching a film made of a thermoplastic resin or containing a thermoplastic resin to a paper substrate using a known heat seal processing device (lamination processing device), a method of applying a water-based heat seal agent in which a thermoplastic resin or a thermoplastic resin composition is dissolved or dispersed in water, or a solvent-based heat seal agent in which a thermoplastic resin or a thermoplastic resin composition is dissolved or dispersed in a solvent, to the paper substrate by a known method such as roll coating, gravure roll coating, kiss coating, etc.

The basis weight of the heat seal layer is preferably 50 g/ ^m2 or less, more preferably 5 g/ ^m2 or more and 35 g/ ^m2 or less, and even more preferably 10 g/ ^m2 or more and 20 g/ ^m2 or less. When the basis weight of the heat seal layer is within the above range, the adhesiveness of the sealed portion 12 of the package 1 can be improved. In addition, all of the required flexibility, softness, and strength of the packaging base material can be more satisfactorily achieved, and further, the sealing property of the package 1 and the adhesiveness of the sealed portion 12 tend to be easily ensured.

As described above, the package 1 of the present invention preferably has a take-out opening for taking out the paper product 11, and preferably has a tear line such as a perforation formed at the take-out opening so that the take-out opening can be opened by cutting along the tear line. The take-out opening is required to be easy to open and difficult to tear, but the package 1 packaging a soft paper product 11 may be difficult to open or may tear depending on the force applied when opening the take-out opening. By setting the basis weight of the heat seal layer within a range of preferably 50 g/ ^m2 or less, more preferably 5 g/ ^m2 to 35 g/ ^m2 , and even more preferably 10 g/ ^m2 to 20 g/ ^m2 , it is possible to achieve both ease of opening the take-out opening and difficulty of tearing.

The basis weight of the heat seal layer can be determined, for example, as follows.
First, prepare a 0.1 M acetic acid solution and a 0.1 M sodium acetate solution. Mix about 830 g of the 0.1 M acetic acid solution and about 160 g of the 0.1 M sodium acetate solution to make the pH 4, and use this as an acetate buffer solution. Add cellulase Onozuka P1500 (manufactured by Yakult Pharmaceutical Co., Ltd.) to this acetate buffer solution so that the amount added is 1 wt%.
50 ml of acetate buffer containing cellulase Onozuka p1500 and 0.5 g of packaging substrate 10 (paper substrate with heat seal layer) are placed in a vial and tightly capped. Next, after shaking for 24 hours at 180 rpm and 40°C, the heat seal layer is sampled from the vial and the mass of the heat seal layer portion is measured. The basis weight of the heat seal layer is calculated from the mass (0.5 g) of the packaging substrate 10 (paper substrate with heat seal layer) and the mass of the sampled heat seal layer according to the following formula.
Basis weight of heat seal layer =
Basis weight of packaging substrate 10 × (mass of heat seal layer / mass of packaging substrate 10)

(2-2) Adhesive Layer In the packaging body 1 of the present invention, the adhesive layer may be formed on the entire surface of the paper substrate or the heat seal layer formed on the paper substrate, or may be formed only on a part of the surface, for example, on a portion where the paper substrates are laminated and joined together. The position, size, and proportion of the adhesive layer on the surface of the paper substrate can be appropriately set.

The adhesive constituting the adhesive layer is not particularly limited, and any known adhesive can be used, such as an ethylene-based adhesive, a two-component curing urethane-based adhesive, a polyester urethane-based adhesive, a polyether urethane-based adhesive, an acrylic-based adhesive, a styrene-acrylic-based adhesive, a polyester-based adhesive, a polyamide-based adhesive, a polyvinyl acetate-based adhesive, an epoxy-based adhesive, or a rubber-based adhesive. Of these, a styrene-acrylic-based adhesive is preferred.

The adhesive layer can be formed by applying the adhesive to the paper substrate or to a heat seal layer formed on the paper substrate by a known method such as roll coating, gravure roll coating, kiss coating, etc.

The basis weight of the adhesive layer (dry coating amount of adhesive) is usually preferably 2 g/ ^m2 or more and 30 g/ ^m2 or less, more preferably 3 g/ ^m2 or more and 25 g/ ^m2 or less, and even more preferably 5 g/ ^m2 or more and 20 g/ ^m2 or less.
The basis weight of the adhesive layer is calculated from the basis weight of the packaging substrate 10 and the basis weight of the paper substrate measured in accordance with JIS P 8124 before the adhesive layer is provided, using the following formula.
Basis weight of adhesive layer = Basis weight of packaging substrate 10 - Basis weight of paper substrate

As mentioned above, in the packaging substrate 10 of the present invention, the seal layer is preferably a heat seal layer and/or an adhesive layer, but a heat seal layer, particularly a heat seal layer containing a polyolefin resin, usually has better adhesion than an adhesive layer, and providing a heat seal layer, preferably a heat seal layer containing a polyolefin resin, may make it easier to package the paper product 11.

(3) Other layers The packaging substrate 10 of the present invention may have other layers in addition to the paper substrate and the seal layer. Examples of the other layers include a water vapor barrier layer, an oxygen barrier layer, a print layer, a printability improving layer, an overprint layer, a light shielding layer, etc. These other layers can be provided, for example, between the paper substrate and the seal layer or on the uppermost surface of the packaging substrate 10, and may be one layer or two or more layers.

(4) Physical properties of the entire packaging substrate As described later, there are various packaging formats for the packaging body 1 according to the present invention, including packaging in such a way that the paper product 11 is wrapped from the manufacturing line direction (conveying direction; MD direction) and packaging in such a way that the paper product 11 is wrapped from the width direction (CD direction) perpendicular to the manufacturing line direction. When wrapping the paper product 11 from the MD direction, the tensile strength of the packaging substrate 10 in the MD direction is preferably 2.0 kN/m or more and 8.0 kN/m or less, more preferably 2.5 kN/m or more and 6.5 kN/m or less, and even more preferably 3.3 kN/m or more and 5.5 kN/m or less. When wrapping the paper product 11 from the CD direction, the tensile strength of the packaging substrate 10 in the CD direction is preferably 0.7 kN/m or more and 4.0 kN/m or less, more preferably 0.9 kN/m or more and 3.0 kN/m or less, and even more preferably 1.1 kN/m or more and 2.0 kN/m or less. By setting the tensile strength in the MD or CD direction of the packaging substrate 10 within the above range, it is possible to improve the adhesion of the seal portion 12 of the package 1. The tensile strength of the packaging substrate 10 can be measured in accordance with JIS P 8113.

When wrapping the paper product 11 from the MD direction, the breaking elongation of the packaging substrate 10 in the MD direction is preferably 0.8% to 2.4%, more preferably 1.0% to 2.1%, and even more preferably 1.2% to 1.8%. When wrapping the paper product 11 from the CD direction, the breaking elongation of the packaging substrate 10 in the CD direction is preferably 3.0% to 7.0%, more preferably 3.5% to 6.7%, and even more preferably 4.0% to 6.0%. By setting the breaking elongation of the packaging substrate 10 in the MD or CD direction within the above range, the adhesiveness of the seal portion 12 of the package 1 can be improved. The breaking elongation of the packaging substrate 10 can be measured in accordance with JIS P 8113.

When wrapping the paper product 11 from the MD direction, the tear strength of the packaging substrate 10 in the MD direction is preferably 300 mN or more and 1600 mN or less, more preferably 450 mN or more and 1200 mN or less, and even more preferably 580 mN or more and 900 mN or less. When wrapping the paper product 11 from the CD direction, the tear strength of the packaging substrate 10 in the CD direction is preferably 400 mN or more and 3000 mN or less, more preferably 700 mN or more and 2300 mN or less, and even more preferably 900 mN or more and 1500 mN or less. By setting the tear strength of the packaging substrate 10 in the MD direction or CD direction within the above range, the adhesiveness of the seal portion 12 of the package 1 can be improved. The tear strength of the packaging substrate 10 can be measured in accordance with JIS P 8116.

The burst strength of the packaging substrate 10 is preferably 90 kPa or more and 310 kPa or less, more preferably 120 kPa or more and 260 kPa or less, and even more preferably 150 kPa or more and 220 kPa or less. By setting the burst strength of the packaging substrate 10 within the above range, the adhesiveness of the seal portion 12 of the package 1 can be improved. The burst strength of the packaging substrate 10 can be measured in accordance with JIS P 8112.

When wrapping the paper product 11 from the MD direction, the bending stiffness of the packaging substrate 10 in the MD direction is preferably 20 μN·m or more and 330 μN·m or less, more preferably 30 μN·m or more and 225 μN·m or less, and even more preferably 60 μN·m or more and 170 μN·m or less. When wrapping the paper product 11 from the CD direction, the bending stiffness of the packaging substrate 10 in the CD direction is preferably 8 μN·m or more and 145 μN·m or less, more preferably 13 μN·m or more and 100 μN·m or less, and even more preferably 20 μN·m or more and 65 μN·m or less. By having the bending stiffness of the packaging substrate 10 in the MD direction or CD direction within the above range, the adhesiveness of the seal portion 12 of the package 1 can be improved. In addition, the required flexibility and softness of the packaging substrate 10 can be easily achieved. The bending stiffness of the packaging substrate 10 can be measured in accordance with ISO 2493. Note that bending stiffness is strongest when a load is applied in the longitudinal direction of the fibers, so when the fiber orientation ratio is close to 1.0, bending stiffness in the MD direction tends to be small and bending stiffness in the CD direction tends to be large.

The thickness of the packaging substrate 10 of the present invention is preferably 40 μm or more and 135 μm or less, more preferably 48 μm or more and 110 μm or less, and even more preferably 68 μm or more and 90 μm or less. When the thickness of the packaging substrate 10 is within the above range, the adhesiveness of the seal portion 12 of the package 1 can be improved. The thickness of the packaging substrate 10 can be measured in accordance with JIS P 8118:1998. The pressure condition of the pressurized surface was 100 kPa.

The density of the packaging substrate 10 is preferably 0.60 g/cm ³ or more and 0.95 g/cm ³ or less, more preferably 0.65 g/cm ³ or more and 0.90 g/cm ³ or less, and even more preferably 0.70 g/cm ³ or more and 0.85 g/cm ³ or less. When the density of the packaging substrate 10 is within the above range, the adhesiveness of the seal portion 12 of the package 1 can be improved. In addition, the required strength, flexibility and softness of the packaging substrate 10 are easily achieved. The density of the packaging substrate 10 can be measured and calculated in accordance with JIS P 8118:1998.

For example, when packaging a tissue paper laminate as the paper product 11, the density of the tissue paper laminate is preferably 0.04 g/cm ³ or more and 0.30 g/cm ³ or less, more preferably 0.07 g/cm ³ or more and 0.25 g/cm ³ or less, and even more preferably 0.10 g/cm ³ or more and 0.20 g/cm ³ or less. When the density of the tissue paper laminate is within the above range, the adhesiveness of the seal portion 12 of the package 1 can be improved when packaging the tissue paper laminate using the packaging base material 10 of the present invention, and the paper product 11 can be easily packaged. The density of the tissue paper laminate is measured as follows. First, the tissue paper laminate is taken from the package 1, and the mass of the tissue paper laminate is measured with an electronic balance after conditioning at 23°C and 50% humidity. Then, the size of the tissue paper laminate (width, depth, height (length of the paper product 11)) is measured with a ruler, and the density is calculated by the following formula.
Density of tissue paper laminate (g/cm ³ )=mass of tissue paper laminate (g)/(width of tissue paper laminate (cm)×depth of tissue paper laminate (cm)×height of tissue paper laminate (cm))

3. Paper Products Regarding the paper product 11 packaged in the package 1 of the present invention, the package 1 of the present invention is particularly suitable for packaging soft paper products such as thin paper. The package 1 of the present invention is particularly suitable for packaging laminated thin paper such as tissue paper, wipers, wet tissue, and paper hand towels.

In addition, when the thin paper is tissue paper, it is preferable that the number of plies is 2. In addition, as for the paper quality, the basis weight per ply is preferably 10 g/m ² or more and 20 g/m ² or less, more preferably 12 g/m ² or more and 18 g/m ² or less, and even more preferably 14 g/m ² or more and 16 g/m ² or less. In addition, the paper thickness of 5 sets (10 sheets) of 2 plies is preferably 0.4 mm/10 sheets or more and 1.1 mm/10 sheets or less, more preferably 0.5 mm/10 sheets or more and 1.0 mm/10 sheets or less, and even more preferably 0.6 mm/10 sheets or more and 0.9 mm/10 sheets or less. By setting the basis weight and paper thickness within the above numerical range, the density of the laminate can be set to an appropriate range, and when packaged with the packaging base material 10, the adhesiveness of the seal portion 12 of the package 1 can be made good.
The basis weight per ply can be measured and calculated in accordance with JIS P 8124. The paper thickness is measured using a thickness gauge (a dial thickness gauge "PEACOCK" manufactured by Ozaki Seisakusho Co., Ltd.). The measurement conditions are a measurement load of 3.7 kPa, a gauge head diameter of 30 mm, a sample is placed between the gauge head and the measuring table, and the gauge is read when the gauge head is lowered at a speed of 1 mm or less per second. The measurement is repeated 10 times and the measurement results are averaged.

Furthermore, when the thin paper is tissue paper, the longitudinal tensile strength per two plies when dry is preferably 2.3 N/25 mm or more and 6.0 N/25 mm or less, more preferably 2.6 N/25 mm or more and 5.0 N/25 mm or less, and even more preferably 2.9 N/25 mm or more and 4.0 N/25 mm or less. The transverse tensile strength per two plies when dry is preferably 0.6 N/25 mm or more and 2.5 N/25 mm or less, more preferably 0.8 N/25 mm or more and 2.2 N/25 mm or less, and even more preferably 1.0 N/25 mm or more and 1.9 N/25 mm or less. By setting the longitudinal and transverse tensile strengths when dry within the above numerical ranges, the density of the laminate can be set to an appropriate range, and when packaged with the packaging substrate 10, the adhesiveness of the seal portion 12 of the package 1 can be improved.
The tensile strength in the machine direction and the cross direction when dry can be measured and calculated in accordance with JIS P 8113.
The measurements of the basis weight, paper thickness and tensile strength are carried out after the paper is kept in equilibrium under the temperature and humidity conditions specified in JIS P 8111 (23±1° C., 50±2% RH).

4. Packaging Format Examples of the packaging format of the package 1 according to the present invention include pillow packaging and gusset packaging.

Pillow packaging is a packaging format in which the packaging substrate is overlapped at both ends in the width direction with the inner faces facing each other so as to encase the packaged item placed on or under a sheet-like packaging substrate in a cylindrical shape, the overlapped portion is formed into a cylindrical shape by heat sealing or the like, the bottom portion or the mouth portion is sealed in a horizontal line by heat sealing or the like to match the length (height) of the bag, and the sealed portion is cut into individual bags. This pillow packaging can be performed using a known device.
There are two types of pillow packaging: vertical pillow packaging, in which the packaging base is fed vertically to wrap the packaged item while filling it from above, and horizontal pillow packaging, in which the packaging base is fed horizontally to wrap the packaged item. When packaging tissue paper, horizontal pillow packaging is preferred from the perspective of packaging speed and the shape of the tissue paper.

Gusset packaging is a packaging format in which the packaging substrate is overlapped at both ends in the width direction with the inner faces facing each other so as to encase the packaged item placed on or under a sheet-like packaging substrate, and the overlapped parts are formed into a cylinder by heat sealing or the like, and both ends of the bottom or mouth are woven inward to create a gusset to match the length (height) of the bag, and the bag is sealed in a horizontal line by heat sealing or the like, and cut into individual bags at the sealed parts. This gusset packaging can be performed using known equipment.

In one embodiment, for example, when using a packaging substrate 10 with bending stiffness in the MD direction of 20 μN·m or more and 330 μN·m or less, the packaging body 1 of the present invention is particularly suitable for use when, for example, the packaging substrate 10 is transported in the form of a continuous sheet, the paper product 11 is placed, and then the paper product 11 is wrapped and packaged in the transport direction (manufacturing line direction; MD direction), and cut to a predetermined dimension in the width direction (CD direction) perpendicular to the transport direction, i.e., when the wrapping direction is the MD direction of the packaging substrate 10. Note that the paper product 11 may be placed after the packaging substrate 10 is cut to a predetermined size, or the packaging substrate 10 may be cut to a predetermined size after the paper product 11 is placed.

In another embodiment, for example, when using a packaging substrate 10 having a bending stiffness in the CD direction of 8 μN·m or more and 145 μN·m or less, the packaging body 1 of the present invention is particularly suitable for use when, for example, the packaging substrate 10 is transported in the form of a continuous sheet, the paper product 11 is placed, and then the paper product 11 is wrapped and packaged from the width direction (CD direction) perpendicular to the transport direction (manufacturing line direction; MD direction), that is, when the wrapping direction is the CD direction of the packaging substrate 10. In this case, in the packaging body 1 of the present invention, it is preferable to select gusset packaging or pillow packaging as the packaging format, and gusset packaging is more preferable. In this case, the packaging substrate 10 may be cut to a predetermined size before the paper product 11 is placed, or the packaging substrate 10 may be cut to a predetermined size after the paper product 11 is placed.
Furthermore, with respect to the MD and CD directions of the packaging substrate 10, it is preferable that the longitudinal direction of the sealed portion 12 of the packaging body 1 is the CD direction of the packaging substrate 10, since this improves the adhesion of the sealed portion 12 having a recess 13 as in the present invention.

Although the present invention has been described above using embodiments, it goes without saying that the technical scope of the present invention is not limited to the scope described in the above embodiments and examples. It will be clear to those skilled in the art that various modifications and improvements can be made to the above embodiments. Furthermore, it is clear from the claims that forms incorporating such modifications or improvements can also be included in the technical scope of the present invention.

The present invention will be described in detail below with reference to examples. Note that the present invention is not limited to the examples shown below.

In the examples and comparative examples, the physical properties of the packaging substrates prepared were measured using the following methods.

(Basis weight of packaging substrate)
The basis weight A of the packaging substrate was measured in accordance with JIS P 8124.

(Basis weight of paper base material and basis weight of heat seal layer)
First, 0.1M acetic acid aqueous solution and 0.1M sodium acetate aqueous solution were prepared. Approximately 830g of 0.1M acetic acid aqueous solution and approximately 160g of 0.1M sodium acetate aqueous solution were mixed to a pH of 4, and this was used as an acetate buffer solution. Cellulase Onozuka p1500 (manufactured by Yakult Pharmaceutical Co., Ltd.) was added to this acetate buffer solution so that the amount added was 1 wt%.
50 ml of acetate buffer containing cellulase Onozuka p1500 and 0.5 g of packaging substrate (paper substrate with heat seal layer) were placed in a vial and tightly capped. Next, after shaking for 24 hours at 180 rpm and 40 ° C, the heat seal layer was sampled from the vial and the mass of the heat seal layer was measured. The basis weight of the paper substrate and the basis weight of the heat seal layer were calculated from the mass (0.5 g) of the packaging substrate (paper substrate with heat seal layer) and the mass of the sampled heat seal layer according to the following formula.
Basis weight of paper base material =
Basis weight of packaging substrate × [(mass of packaging substrate − mass of heat seal layer) / mass of packaging substrate]
Basis weight of heat seal layer =
Basis weight of packaging substrate × (mass of heat seal layer / mass of packaging substrate)

(Basis weight of adhesive layer (amount of adhesive applied))
The basis weight of the adhesive layer was calculated according to the following formula from the basis weight of the packaging base material determined as above and the basis weight of the paper base material measured in accordance with JIS P 8124 before providing the adhesive layer.
Basis weight of adhesive layer = grammage of packaging substrate - grammage of paper substrate

(Thickness of packaging substrate)
The thickness of the packaging substrate was measured in accordance with JIS P 8118: 1998 using an automatic elevating paper thickness gauge standard model TM-600 (manufactured by Kumagai Riki Kogyo Co., Ltd.) The pressure condition of the pressing surface was 100 kPa.

(Density of packaging substrate)
The density of the packaging base material was measured and calculated in accordance with JIS P 8118:1998.

(Tensile strength in MD and CD of packaging substrate)
The tensile strength in the MD and CD directions of the packaging substrate was measured in accordance with JIS P 8113.

(Elongation at break in MD and CD directions of packaging substrate)
The breaking elongation in the MD and CD directions of the packaging substrate was measured in accordance with JIS P 8113.

(Tear strength in MD and CD of packaging substrate)
The tear strength in the MD and CD directions of the packaging substrate was measured in accordance with JIS P 8116.

(Burst strength of packaging substrate)
The burst strength of the packaging substrate was measured in accordance with JIS P 8112.

(Measurement of bending stiffness in MD and CD directions of packaging substrate)
The bending stiffness of the packaging substrate in the MD and CD directions was measured using an L&W bending tester (manufactured by Lorentzen & Wettre) in accordance with the method described in ISO 2493. The packaging substrate was a test piece with a width of 38 mm and a length of 100 mm, and the measured value when the bending angle was 15 degrees and the bending length (span of the sample stage) was 10 mm was taken as the bending resistance (load), and the bending stiffness (μN·m) was calculated using the following formula.
Bending stiffness (μN·m) = 60 × bending resistance (mN) × bending length 10 (mm) ² ÷ (π × bending angle 15 (°) × sample width 38 (mm))
If it is not possible to obtain a test specimen with a length of 100 mm, the length of the test specimen may be shortened. The test specimen should not include the perforation of the opening for removal, but may include the perforation if it is necessary to include the perforation in order to ensure the size of the test specimen.

Example 1
(Packaging substrate)
A paper base material was prepared using 100% by weight of softwood unbleached kraft pulp (NUKP) as the pulp raw material. A polyethylene layer was then formed as a heat seal layer on the paper base material by extrusion to prepare a packaging base material. The basis weight of the prepared packaging base material, the basis weight of the paper base material, and the basis weight of the heat seal layer, as well as the thickness, density, tensile strength in the MD and CD directions, breaking elongation in the MD and CD directions, burst strength, bending stiffness in the MD and CD directions, and tear strength in the MD and CD directions were measured and the results are shown in Table 1.

(Tissue paper packaging (gusset packaging))
Using the prepared packaging base material, a package was prepared with dimensions of 18 cm in the MD direction of the packaging base material, 11 cm in the CD direction of the packaging base material, and 5 cm in height. Then, 50 sets of 2-ply tissue paper were placed in this package as a paper product, and the package was sealed by gusset packaging to obtain a tissue paper package. The paper product was wrapped in the CD direction while being packaged. The tissue paper package had three seal parts, and the recesses were approximately square-shaped recesses with a circumference of 4 mm, and 500 recesses were provided in each seal part in a lattice shape, with six recesses arranged in the width direction.
Then, in the tissue paper package, the pitch of the recesses in the seal portion and the depth B of the recesses were measured, and the ratio of the depth (B) of the recesses to the basis weight (A) of the packaging substrate was calculated as (B/A) x 100. The measurement of the pitch and depth of the recesses was performed according to the measurement method described above.

(Adhesion of the seal part)
The prepared tissue paper packages were evaluated by 30 monitors for the adhesiveness of the sealed portion (whether the sealed portion was properly adhered and whether it was burnt) when the packaging base material was opened from the sealed portion. The evaluation criteria were as follows.
A: 0-1 person who felt that the seal was weakly adhered and/or burnt B: 2-3 people who felt that the seal was weakly adhered and/or burnt C: 4-6 people who felt that the seal was weakly adhered and/or burnt D: 7-15 people who felt that the seal was weakly adhered and/or burnt E: 16-30 people who felt that the seal was weakly adhered and/or burnt

(Example 2) to (Example 12), (Comparative Example 1) to (Comparative Example 4)
In Examples 2 to 12 and Comparative Examples 1 to 4, packaging base materials having the physical properties shown in Table 1 were prepared in the same manner as in Example 1, and tissue paper packages (gusseted packages) were prepared using these in the same manner as in Example 1, and the adhesiveness of the sealed portion was evaluated. However, in Example 10, instead of providing a polyethylene layer as a heat seal layer on the paper base material, a styrene-acrylic adhesive layer (adhesive coating amount: 10.8 g/m ² ) was provided. In Example 11, 26 sets of 2-ply tissue paper were used as the paper product, and in Example 12, 72 sets of 2-ply tissue paper were used as the paper product to prepare tissue paper packages.

As is clear from the results shown in Table 1, the adhesiveness of the sealed portion was good in all of the packages of Examples 1 to 12. In contrast, the adhesiveness of the sealed portion was poor in all of Comparative Examples 1 to 4.
Therefore, the packaging body of the present invention can provide a packaging body for paper products having good adhesion at the seal portion, even when the packaged item is a paper product, particularly a paper product such as tissue paper.

1 Packaging body 10 Packaging base material 11 Paper product (packaged item)
12 Sealing portion 13 Recess

Claims (5)

A package in which one or more paper products are entirely covered with a packaging base material, and the paper products are sealed by at least one seal portion,
The paper product is a laminated tissue paper,
The packaging substrate includes at least a paper substrate and a seal layer,
The basis weight of the packaging substrate is 35 g/m ² or more and 105 g/m ² or less,
The basis weight of the paper base material of the packaging base material is 25 g/m ² or more and 88 g/m ² or less,
The ratio of the basis weight of the paper base material to the basis weight of the packaging base material is 60% or more and 95% or less,
The sealing portion is provided at an end portion where the packaging base material overlaps,
The seal portion has at least two recesses each having a circumferential length of 0.6 mm or more and 16 mm or less, the ends of the recesses being adjacent to each other with a distance of 0.2 mm or more and 6 mm or less between them,
The depth of the recess is equal to or greater than 0.05 mm and equal to or less than 0.49 mm,
The sealing layer is an adhesive layer,
A packaging material for paper products , characterized in that the packaging material is a gusset packaging or a pillow packaging . The packaging for paper products according to claim 1, characterized in that the pitch of the recesses in a direction perpendicular to the longitudinal direction of the sealing portion is 0.3 mm or more and 5.9 mm or less. The packaging body for paper products according to claim 1 or 2, characterized in that (depth of the recess/basis weight of the packaging substrate) x 100 is 0.07 or more and 1.5 or less. The packaging body for paper products according to any one of claims 1 to 3, characterized in that the bending stiffness of the packaging base material in the MD direction is 20 μN·m or more and 330 μN·m or less. The packaging body for paper products according to any one of claims 1 to 4, characterized in that the bending stiffness of the packaging base material in the CD direction is 8 µN·m or more and 145 µN·m or less.