Packaging sheet, individually packaged absorbent article individually packaging absorbent article

Abstract

A packaging sheet which is made of paper and is printed on the surface while being conveyed in the fiber direction, is used for individually packaging an absorbent article, and has a tensile strength in the fiber direction of 16-25 N (inclusive). The packaging sheet satisfies 8.45 < = X * (1-Y / 100), where X (N) is the tensile strength of the packaging sheet in the fiber direction before the packaging sheet is printed, and Y (%) is the ratio of the area of at least one of the ink for printing and the heat sealing agent for bonding the packaging sheets to the entire area of the packaging sheet.

Description

Technical Field

[0001] The present invention relates to a packaging sheet, a separately-packaged absorbent article formed by separately packaging an absorbent article with the same, and a method for manufacturing the packaging sheet. Background Art

[0002] For most absorbent articles such as sanitary napkins for physiological use, pantiliners, incontinence pads, etc., for reasons such as hygiene during storage and convenience during carrying, they are provided as separately-packaged absorbent articles (separate packages) in a state of being separately packaged and sealed with a packaging sheet.

[0003] Such separately-packaged absorbent articles are carried around while the absorbent articles are stored in the packaging sheet. Therefore, there are also cases where it is desired to print on the surface of the packaging sheet to avoid being able to tell at a glance that it is an absorbent article.

[0004] Patent Document 1 discloses an absorbent article package configured to include an absorbent article and a packaging sheet for packaging the absorbent article, and having a pattern that can be visually recognized from the outside.

[0005] Patent Document 1: International Publication No. 2020 / 095764 Summary of the Invention

[0006] [Problems to be Solved by the Invention]

[0007] In recent years, from the perspective of environmental problems, it has been promoted to use paper materials to form the packaging sheet instead of the conventional non-woven fabric or plastic film. In the case of using paper materials to form the packaging sheet, it is necessary to avoid the packaging sheet breaking, i.e., so-called paper breakage, during printing and the like.

[0008] The present invention has been completed in view of the problems of the above-mentioned conventional technologies, and the object is to provide a packaging sheet, a separately-packaged absorbent article formed by separately packaging an absorbent article with the same, and a method for manufacturing the packaging sheet, which can avoid breakage when printing is performed on the surface.

[0009] [Means for Solving the Problems]

[0010] In order to achieve the above object, the present invention provides a paper packaging sheet that is transported in the fiber direction while printing is performed on the surface and is used for separately packaging an absorbent article. Among them,

[0011] the tensile strength of the packaging sheet in the fiber direction is 16 N or more and 25 N or less,

[0012] When the tensile strength of the packaging sheet in the fiber direction before printing is set to X (N), and the ratio of the area coated with at least one of the ink for printing and the heat-sealing agent for bonding the packaging sheets to each other to the total area of the packaging sheet is set to Y (%), the following is satisfied

[0013] 8.45 ≤ X × (1 - Y / 100).

[0014] In the present invention configured as described above, by setting the tensile strength of the packaging sheet in the conveying direction to 16 N or more and 25 N or less, and setting the tensile strength of the packaging sheet before printing and the ratio of the area coated with at least one of the ink for printing and the heat-sealing agent to the total area of the packaging sheet to satisfy the above conditions, it is possible to avoid breakage when printing is performed on the surface.

[0015] Furthermore, it can be configured such that the MMD (variation in average coefficient of friction) of the surface to be printed is 0.050 or less.

[0016] In the packaging sheet configured as described above, the printing on the surface can be made uniform, thereby improving the aesthetics.

[0017] Furthermore, it can be configured such that the basis weight of the paper is 30 gsm or less.

[0018] In the packaging sheet configured as described above, it is possible to avoid problems such as an increase in material costs due to a high basis weight of the paper, poor operability due to increased toughness of the paper, and excessive noise when opening.

[0019] Furthermore, a single-pack absorbent article, which is a single-pack absorbent article obtained by individually packaging the absorbent article with the packaging sheet according to claim 1 or 2, wherein

[0020] the packaging sheet individually packages the absorbent article by folding and sealing the edge portions,

[0021] the sealing strength at the edge portions is less than the tensile strength.

[0022] In the single-pack absorbent article configured as described above, when the sealed portion is peeled off to take out the absorbent article, the packaging sheet is not easily broken.

[0023] Furthermore, a method for manufacturing a packaging sheet for individually packaging an absorbent article, the method for manufacturing the packaging sheet including at least one of the following steps:

[0024] a printing step of performing printing on the surface of the packaging sheet while conveying the packaging sheet in the fiber direction; and

[0025] Coating step: While transporting the packaging sheet in the fiber direction, a heat-sealing agent is coated on the surface of the packaging sheet.

[0026] The tensile strength of the packaging sheet in the fiber direction is 16 N or more and 25 N or less.

[0027] When the tensile strength of the packaging sheet in the fiber direction before printing is set to X (N), and the ratio of the area coated with at least one of the ink for the printing and the heat-sealing agent to the total area of the packaging sheet is set to Y (%), the following is satisfied:

[0028] 8.45 ≤ X × (1 - Y / 100).

[0029] [Effects of the Invention]

[0030] According to the present invention, it is possible to avoid breakage when printing is performed on the surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a plan view of an embodiment of the individually packaged absorbent article of the present invention.

[0032] Figure 2 is Figure 1 a plan view of the state after the individually packaged absorbent article shown is unfolded.

[0033] Figure 3 is along Figure 1 a sectional view taken along line I-I shown.

[0034] Figure 4 is Figure 1 an enlarged view of part II shown.

[0035] Figure 5 is a diagram for explaining Figures 1 to 3 a printing method for printing on the packaging sheet shown.

[0036] Figure 6 is a diagram showing Figures 1 to 3 the detailed structure of the printed surface of the packaging sheet shown. DETAILED DESCRIPTION OF THE INVENTION

[0037] Hereinafter, embodiments of the present invention will be described while referring to the attached Figure 1 drawings. In addition, unless otherwise specified, the same or corresponding structures in each drawing may sometimes be denoted by the same reference numerals and the description thereof may be omitted.

[0038] [Overall Structure of the Individually Packaged Absorbent Article]

[0039] Figure 1It is a top view of an embodiment of a separately packaged absorbent article of the present invention. Figure 2 is Figure 1 a top view of the state after the separately packaged absorbent article 100 shown is unfolded, and is a view observed from the inner surface of the packaging sheet 10 or from the skin side of the absorbent article 1. In addition, Figure 3 is along Figure 1 a sectional view taken along the line I-I shown.

[0040] As Figures 1 to 3 shown, this embodiment is a separately packaged absorbent article 100, which includes a packaging sheet 10 and an absorbent article 1 separately packaged by the packaging sheet 10. As Figure 2 shown, the packaging sheet 10 is, for example, in an elongated shape in the unfolded state, and has a long side direction (longitudinal direction) D1 and a short side direction (lateral direction) D2 orthogonal to the long side direction. In addition, the long side direction D1 and the short side direction D2 of the packaging sheet 10 also respectively correspond to the long side direction and the short side direction of the absorbent article 1.

[0041] <Absorbent article>

[0042] The absorbent article 1 packaged by the packaging sheet 10 has a shape for being worn in a manner opposite to the discharge port of body fluids (such as menstrual blood, leucorrhea, urine, etc.), and is, for example, a flat and elongated article. As a specific example of the absorbent article 1, sanitary napkins, pantiliners (leucorrhea pads), light incontinence pads, etc. can be cited. In this specification, the example where the absorbent article is a sanitary napkin is described.

[0043] For example Figure 2 shown, the absorbent article 1 has a liquid-permeable topsheet 3, a liquid-impermeable backsheet (not shown), and an absorber 4 disposed between the topsheet 3 and the backsheet.

[0044] As the backsheet, a sheet material having at least liquid impermeability such as an olefin resin sheet such as polyethylene and polypropylene can be used. A laminated nonwoven fabric in which a nonwoven fabric is laminated on an upper layer of a polyethylene sheet or the like, and a laminated sheet of a nonwoven fabric in which a waterproof film is further interposed between nonwoven fabrics to substantially ensure liquid impermeability can be used. In addition, a sheet material having moisture permeability can also be used.

[0045] As the topsheet 3, a perforated or non-perforated nonwoven fabric, a porous plastic sheet, etc. are suitably used. As the raw material fibers constituting the nonwoven fabric, for example, the following fibers can be used singly or in combination of two or more: synthetic fibers such as olefins such as polyethylene or polypropylene, polyester, polyamide; regenerated fibers such as rayon and cuprammonium fiber; blended fibers of these fibers; and natural fibers such as cotton.

[0046] The absorber 4 is not limited as long as it is a material capable of absorbing and retaining body fluids, and preferably includes cotton pulp and a water-absorbing polymer. As the water-absorbing polymer, superabsorbent polymer (SAP) granulated powder, superabsorbent fiber (SAF), or a combination thereof can be used. As the pulp, fibers composed of cellulose fibers and rayon can be cited. Among them, cellulose fibers are chemical pulp, dissolving pulp, etc. obtained from wood, and rayon is rayon, acetate, etc. As the pulp, it can be hardwood pulp obtained from hardwood, softwood pulp obtained from softwood, or a mixed pulp thereof. In addition, the pulp can also be recycled pulp regenerated from used pulp.

[0047] The thickness of the absorber 4 can be 0.5 to 25 mm. The absorber 4 can also adopt a structure in which the area corresponding to the body fluid discharge port (body fluid discharge port corresponding area) or the area opposite to the gluteal groove behind the body fluid discharge port corresponding area bulges. The absorber 4 has dimensions and a shape that do not exceed those of the topsheet 3 and the backsheet. At the front and rear edge portions of the absorber, the outer edges of the backsheet and the topsheet 3 are joined by an adhesive such as hot melt adhesive, or joining means such as heat sealing or ultrasonic sealing.

[0048] As Figure 2 shown, on the outer side of the lateral side of the absorber 4, side sheets 7 can also be provided along the long side direction D1 at both ends in the short side direction D2. As the side sheets 7, water-repellent non-woven fabric or water-attracting non-woven fabric can be used.

[0049] In addition, in Figures 1 to 3 the example shown, the absorbent article 1 is wingless, that is, a so-called wingless type, but the absorbent article 1 can also be configured as an article with wings having wings extending laterally respectively. The wings can be formed by joining the side sheets and the backsheet.

[0050] In addition, on the backsheet side (non-skin side, that is, the side facing the underwear when worn) of the absorbent article 1, an anti-slip adhesive portion can also be provided to prevent the absorbent article 1 from shifting from the underwear when the absorbent article 1 is worn on the underwear. The anti-slip adhesive portion is formed, for example, as a plurality of strips extending in the long side direction D1 or the short side direction D2.

[0051] The overall length of the absorbent article 1 can be set to 140 to 430 mm, and the width of the absorbent article 1 (the width of the main body after removing the wings in the case of having wings) can be set to 40 to 130 mm.

[0052] <Packaging sheet>

[0053] The packaging sheet 10 in this embodiment is paper. By using the paper-made packaging sheet 10, it is possible to contribute to plastic reduction, thereby contributing to the achievement of sustainable development goals. In addition, paper can give a unique texture, such as an appearance with a soft impression of natural materials and a skin touch.

[0054] More than 50% of the packaging sheet 10 is composed of pulp fibers, and design printing is performed on the exposed surface that is exposed to the outside when the absorbent article 1 is individually packaged. The detailed conditions of the packaging sheet 10 will be described below.

[0055] The size of the packaging sheet 10 can correspond to the size and shape of the absorbent article 1 to be packaged. For example, in the state where the packaging sheet 10 is fully unfolded (the state where it is not folded back), the length in the long side direction D1 (sometimes simply referred to as the length) can be set to 100 to 450 mm, and the length in the short side direction D2 (sometimes simply referred to as the width) can be set to 70 to 250 mm. In the illustrated example, the packaging sheet 10 has a rectangular shape in the unfolded state, but it can also have a shape such as an oval.

[0056] <Packaging structure for individually packaging absorbent articles>

[0057] As Figure 1 and Figure 3 shown, the absorbent article 1 is packaged by being folded together with the packaging sheet 10 to form an individually packaged absorbent article 100. When folding, as Figure 2 shown, first, the absorbent article 1 is placed on the inner surface of the packaging sheet 10 in a state where the backsheet side of the absorbent article 1 faces the inner surface of the packaging sheet 10. Then, the packaging sheet 10 and the absorbent article 1 are folded together in the long side direction D1 at the first fold line F1 and the second fold line F2 along the width direction D2. More specifically, at the first fold line F1, the first region R1 including one end 11 in the long side direction D1 of the packaging sheet 10 is folded back in the long side direction D1, and at the second fold line F2, the second region R2 including the other end 12 in the long side direction D1 of the packaging sheet 10 is folded back. The region between the first region R1 and the second region R2 of the packaging sheet 10 is the third region R3. In the illustrated example, in the packaging sheet 10, the second region R2 is first folded, and then the first region R1 is folded so as to overlap on the outer surface of the second region R2 ( Figure 1 and Figure 2 ), but the folding order of the first region R1 and the second region R2 can also be reversed. In this way, after rolling the packaging sheet 10 and the absorbent article 1 into a triple fold (inner triple fold) to wrap the absorbent article 1, the two edge portions in the short side direction D2 are sealed along the long side direction D1 respectively to form the sealing portions 15.

[0058] Such a packaging form with three or more folds can be formed relatively simply, can hygienically wrap the absorbent article 1, and the absorbent article 1 can be easily taken out. In addition, the folding form is not limited to three folds, and can also be set to four or more folds, or can be set to two folds.

[0059] <Sealing portion>

[0060] As Figure 1 shown, in the single package absorbent article 100, the regions where the absorbent article 1 is absent at both edge portions in the short side direction D2 are respectively sealed to form the sealing portion 15. In the present embodiment, the sealing portion 15 is formed by applying a heat-sealing agent on the sealed surface of the packaging sheet 10 and then passing it between a pair of heated rollers to press and bond the packaging sheets 10 to each other in the thickness direction.

[0061] As Figure 1 shown, the sealing portion 15 is formed, for example, over the entire length in the long side direction D1 of the single package absorbent article 100. Thus, from the viewpoint of being able to prevent waste chips and dust, or fingers or small objects from inadvertently invading from the end edges in the short side direction (sealability can be obtained), it is preferable.

[0062] The range in the short side direction D2 where the sealing portion 15 is provided is, for example, a range from the end edge in the short side direction D2 inward to 20 mm. The sealing portion 15 can also be formed over the entire above range, or can be formed in a part of the above range, for example, at a position separated inward from the end edge in the short side direction D2. The length (width) of the sealing portion 15 itself in the short side direction D2 is preferably 3 to 15 mm.

[0063] Figure 4 is Figure 1 an enlarged view of part II shown, showing the part including the sealing portion 15.

[0064] As Figure 4 shown, the sealing portion 15 includes, for example, a plurality of crimped portions (or joined portions) 15a that are separated from each other in a plan view. Each crimped portion 15a is a portion where the packaging sheets 10 are joined to each other by crimping in the thickness direction. In the illustrated example, the portions other than the plurality of crimped portions 15a are non-joined portions where the packaging sheets 10 are not joined together. In this way, by the plurality of crimped portions 15a being separated and scattered, for example, compared with the case where the packaging sheets 10 are continuously joined to each other over the entire surface of the sealing portion 15, etc., the packaging sheets can be easily peeled from each other at the time of opening, and the openability can be improved. In addition, it is also possible to prevent the two edge portions of the single package absorbent article 100 from becoming overly hard and damaging the skin feel.

[0065] In addition, the plan view shape of each crimped portion 15a is in Figure 4In the example shown, it is a square, but it is not limited to the shape shown in the figure. For example, it can also be a rectangle, a parallelogram, or other quadrilaterals other than a square, as well as polygons other than quadrilaterals, a circle, an ellipse, a heart shape, a star shape, a droplet shape, etc. In addition, the size of each of the crimping portions 15a can be, for example, a square with a side length of 0.25 to 2.5 mm, or a size having an area equivalent thereto. In addition, the arrangement of the plurality of crimping portions 15a can be in a lattice shape as shown in Figure 4 or can be configured in a staggered arrangement.

[0066] (Adhesive strip)

[0067] As shown in Figures 1 to 3 , in the single-packaged absorbent article 100, an adhesive strip 30 can be provided at the center in the short-side direction D2 near the edge of the first region R1 (one end 11 of the packaging sheet 10). And, as shown in Figure 1 , the adhesive strip 30 can also be provided on the first region R1 and the second region R2 so as to straddle one end 11 of the packaging sheet 10. The adhesive strip 30 has a base portion 31 attached to the first region R1 and a front end portion 32 attached to the second region R2 when viewed from above.

[0068] By providing the adhesive strip 30, when opening the single-packaged absorbent article 100, the user can pinch the adhesive strip 30 (more specifically, the front end portion 32 of the adhesive strip 30) and lift and pull the first region R1, so that the opening becomes easier. In addition, due to the presence of the adhesive strip 30, when replacing the absorbent article, after wrapping the used absorbent article with the packaging sheet obtained from the newly opened single-packaged absorbent article, the end of the packaging sheet can be pasted to other parts of the packaging sheet. Through this transfer, it is possible to prevent the used absorbent article from being exposed due to the opening of the packaging sheet, etc., and thus the used absorbent article can be discarded in a hygienic manner.

[0069] The width (length in the short-side direction D2) of the adhesive strip 30 can be preferably 5 to 30 mm, more preferably 10 to 20 mm. In addition, the overall length of the adhesive strip 30 can be preferably 10 to 50 mm, more preferably 15 to 40 mm.

[0070] <Strength of packaging sheet and coating area ratio of ink>

[0071] When manufacturing the single-packaged absorbent article 100 configured as described above, first, the packaging sheet 10 is printed.

[0072] Figure 5 is a diagram for explaining the printing method for printing the packaging sheet 10 shown in Figures 1 to 3 .

[0073] When manufacturing asFigure 1 In the case of the packaging sheet 10 shown, as Figure 5 shown, in the printing process, while multiple packaging sheets 10 are connected in the fiber direction (MD direction: machine direction) as the short side direction, printing is performed on their surfaces. At this time, the packaging sheet 10 is being printed while being conveyed with the short side direction as the conveying direction A. If the tensile strength of the packaging sheet 10 is weak, the packaging sheet may break during printing, i.e., so-called paper breakage occurs.

[0074] In addition, if the packaging sheet 10 is printed, the printing causes the ink to penetrate into the packaging sheet 10, resulting in relaxation in the fiber structure and weakening of the bond between the fibers. This also weakens the tensile strength and causes paper breakage. This phenomenon is not limited to the ink used for printing. Even in the case where there is no printing process, that is, in the coating process of applying a heat-sealing agent for sealing the packaging sheets 10 to each other on the packaging sheet 10, the coating of the heat-sealing agent also causes this phenomenon.

[0075] Figure 6 It shows for Figures 1 to 3 a printing example of the packaging sheet 10 shown. (a) is a top view of an individually packaged absorbent article, and (b) is an enlarged view of part B in the case of dot printing.

[0076] When printing is performed on the packaging sheet 10, as Figure 6 shown in (a), there are a colored area 41 colored by the printing and a non-colored area 42 where no printing is performed. Here, in the case of so-called full-surface printing by intaglio printing, ink is applied to the entire colored area 41. Therefore, the ink application area ratio with respect to the entire packaging sheet 10 is:

[0077] (Area of the colored area 41) / (Area of the entire packaging sheet 10).

[0078] On the other hand, in the case of performing printing by dot printing, as Figure 6 shown in (b), even in the colored area 41 where printing is performed, there are a coated area 41a where ink is applied and a non-coated area 41b where no ink is applied. Therefore, the ink application area ratio with respect to the entire packaging sheet 10 is:

[0079] (Area of the coated area 41a) / {(Area of the non-colored area 42) + (Area of the non-coated area 41b)}.

[0080] That is, in dot printing, even when printing is performed on the entire packaging sheet 10, for the ink application area ratio with respect to the entire packaging sheet 10, it is not necessary to set it to 100%.

[0081] Therefore, for various papers considered to be used as the packaging sheet 10, the printability operability with respect to the coating area ratio of the ink and the heat-sealing agent to the entire packaging sheet 10 was examined. At this time, since the packaging sheet 10 in the present embodiment is printed while being conveyed in the fiber direction of the paper, the tensile strength in the fiber direction of the packaging sheet 10 is measured as the tensile strength. In addition, in this examination, the measurement was performed at room temperature using a tensile testing machine of TENSILON. As the measurement conditions, the paper substrate as the packaging sheet 10 was cut into single pieces that were 120 mm in the fiber direction and 25 mm in the direction orthogonal to the fiber direction, and the tensile strength was measured while stretching at a speed of 500 mm / sec in the fiber direction. The interval between the jigs at this time was set to 50 mm.

[0082] [Table 1]

[0083]

[0084] As shown in Table 1, as Example 1, in Yunlong paper with a basis weight of 14 gsm (manufactured by Marubishi Paper Mills, Ltd.), the Yunlong paper used was not coated with a heat-sealing agent on the packaging sheet 10, and the coating area ratio of the ink to the entire packaging sheet 10 was 20%. In addition, as Example 2, in Yunlong paper with a basis weight of 14 gsm (manufactured by Marubishi Paper Mills, Ltd.), the Yunlong paper used was not coated with ink on the packaging sheet 10, and the coating area ratio of the heat-sealing agent to the entire packaging sheet 10 was 50%. In addition, as Example 3, in crepe paper with a basis weight of 18 gsm (manufactured by Oji Paper Co., Ltd.), the crepe paper used was not coated with ink on the packaging sheet 10, and the coating area ratio of the heat-sealing agent to the entire packaging sheet 10 was 100%. In addition, as Example 4, in crepe paper with a basis weight of 18 gsm (manufactured by Oji Paper Co., Ltd.), the crepe paper used was not coated with a heat-sealing agent on the packaging sheet 10, and the coating area ratio of the ink to the entire packaging sheet 10 was 12%. In addition, as Example 5, in crepe paper with a basis weight of 18 gsm (manufactured by Oji Paper Co., Ltd.), the crepe paper used was not coated with a heat-sealing agent on the packaging sheet 10, and the coating area ratio of the ink to the entire packaging sheet 10 was 35%. In addition, as Comparative Example 1, in Yunlong paper with a basis weight of 17 gsm (manufactured by Marubishi Paper Mills, Ltd.), the coating area ratio of the heat-sealing agent to the entire packaging sheet 10 of the Yunlong paper used was 100%, and the coating area ratio of the ink to the entire packaging sheet 10 was 72%. In addition, as Comparative Example 2, in chemical fiber paper PM with a basis weight of 14 gsm (manufactured by Marubishi Paper Mills, Ltd.), the coating area ratio of the heat-sealing agent to the entire packaging sheet 10 of the chemical fiber paper PM used was 100%, and the coating area ratio of the ink to the entire packaging sheet 10 was 72%. In addition, as Comparative Example 3, Yunlong paper with a basis weight of 25 gsm was used. In addition, as Comparative Example 4, in Kinkoi paper with a basis weight of 24.4 gsm (manufactured by Oji Paper Co., Ltd.), the coating area ratio of the heat-sealing agent to the entire packaging sheet 10 of the Kinkoi paper used was 100%, and the coating area ratio of the ink to the entire packaging sheet 10 was 72%. In addition, as Comparative Example 5, in Kinkoi paper with a basis weight of 30 gsm (manufactured by Oji Paper Co., Ltd.), the coating area ratio of the heat-sealing agent to the entire packaging sheet 10 of the Kinkoi paper used was 100%, and the coating area ratio of the ink to the entire packaging sheet 10 was 72%. In addition, the chemical fiber paper PM is a paper composed of 15% artificial fiber and 85% pulp.

[0085] In Table 1, for printability, those that can be printed without paper breakage are marked with "○", while those that cannot be printed due to paper breakage are marked with "×". In addition, for usability, it was judged whether there were any adverse conditions affecting usability, such as the edges of the individual packages becoming sharp or making a rustling sound due to the hardening of the paper. And for those with no problems in usability, they are marked with "○", for those with hardened individual packages and making sounds during use, they are marked with "×", and for those with adverse conditions in only one of hardness or sound, they are marked with "△".

[0086] Thus, in Comparative Example 3 and Comparative Example 5, the edges of the individual packages became sharp and the rustling sound during use increased. From this, it can be seen that for those with a tensile strength exceeding 54 N, the edges of the individual packages become sharp and the rustling sound during use increases. In addition, among the papers with a tensile strength of 17.7 N used in Examples 3 to 5, there were also cases of paper breakage during printing. On the other hand, in Comparative Example 1 using a paper with a tensile strength of 25.7 N, there was no paper breakage. From this, it can be seen that for those with a tensile strength of 25 N or less, there is a possibility of paper breakage during printing.

[0087] Therefore, for those with a tensile strength of 25 N or less, an attempt was made to confirm the coating area ratio of the ink and the heat-sealing agent with respect to the entire packaging sheet 10. Thus, for the paper with a tensile strength of 17.7 N, in Example 3 where the coating area ratio of the heat-sealing agent with respect to the entire packaging sheet 10 was set to 100%, paper breakage occurred during printing. On the other hand, for the paper with a tensile strength of 17.7 N, in Example 5 where the coating area ratio of the ink with respect to the entire packaging sheet 10 was set to 35%, there was no paper breakage during printing.

[0088] In addition, for the paper with a tensile strength of 16.9 N, in Example 2 where the coating area ratio of the ink with respect to the heat-sealing agent of the entire packaging sheet 10 was set to 50%, there was no paper breakage during printing.

[0089] Here, corresponding to the strength of the paper, the coating area ratio of the printable ink increases proportionally. That is, the greater the tensile strength of the paper, the greater the coating area ratio of the printable ink that can be set. Therefore, as a threshold for printable operation

[0090] (Tensile strength)×(1 - Coating area ratio of ink (heat-sealing agent))

[0091] becomes a fixed value.

[0092] Therefore, based on the above results, for the paper used in Example 2 with the weakest tensile strength in this test, substituting 50% of the coating area ratio of the heat-sealing agent with "○" for printability into the above formula, and substituting 16.9 N as the tensile strength, then it is derived

[0093] 16.9×(1 - 0.50) = 8.45

[0094] This value. And if this value is set as the lower limit, paper breakage will not occur during printing.

[0095] From this, it can be known that when the tensile strength is set as X (N) and the ratio of the area of at least one of the coating ink and the heat - sealant to the total area of the packaging sheet is set as Y (%), satisfying

[0096] 8.45 ≤ X×(1 - Y / 100),

[0097] paper breakage will not occur during printing. In addition, substituting any case where the printing operability is "○" for the algebra X and Y, the above formula holds.

[0098] In addition, for Yunlong paper, chemical fiber paper PM, and Kinkoi paper, even when the coating area ratio of the heat - sealant is 100%, they have printing operability. Therefore, among papers with a tensile strength exceeding 25 N, there is no need to set a limit on the coating area. In addition, it can be considered that for papers with a tensile strength less than 16 N, regardless of the coating area ratio of the ink and the heat - sealant, their printing operability is insufficient, and it is also easy to cause the individual package to rupture during opening.

[0099] Based on this result, as the packaging sheet 10, its tensile strength in the conveying direction during printing is 16 N or more and 25 N or less. And when the tensile strength of the packaging sheet 10 before printing is set as X (N) and the ratio of the area of at least one of the ink used for printing and the heat - sealant used for bonding the packaging sheets to the total area of the packaging sheet 10 is set as Y (%), satisfying

[0100] 8.45 ≤ X×(1 - Y / 100),

[0101] then when using this packaging sheet 10, it is possible to avoid breakage when printing on the surface. And at the same time, it is possible to avoid the edges of the individual packages becoming sharp and the rustling sound during use from becoming louder.

[0102] Thus, while ensuring operability and usability, it is possible to use a thin paper as the packaging sheet 10 and perform printing, thereby being able to provide an individual package absorbent article 100 using a packaging sheet 10 made of paper with high design.

[0103] Moreover, at this time, if the surface of the packaging sheet 10 becomes rough, the printing will not be uniform and the aesthetic appearance will deteriorate. Therefore, MMD (variation in average coefficient of friction), which is an index of the smoothness of the paper surface, was measured, and an experiment was conducted on whether the printability was high. As a result, it was found that paper with an MMD of 0.050 or less on the surface before printing has printability, and by using this paper, the designability of printing on the surface of the packaging sheet 10 can be improved.

[0104] In addition, if the basis weight of the paper is high, the material cost will increase. In addition, the toughness of the paper becomes stronger, which results in poor operability and a problem of excessive noise when opening. Therefore, the basis weight is preferably 30 gsm or less.

[0105] <Sealing part strength>

[0106] As described above, in the single-pack absorbent article 100, after the packaging sheet 10 and the absorbent article 1 are folded into three folds (inner three folds) to wrap the absorbent article 1, the two edge portions in the short side direction D2 are sealed along the long side direction D1 to form a sealing part 15. Then, by peeling the packaging sheets 10 joined at the sealing part 15 from each other, the single-pack absorbent article 100 is opened and the absorbent article 1 is taken out.

[0107] Here, if the sealing strength at the sealing part 15 is high, the packaging sheet 10 may be broken when the packaging sheets 10 are peeled from each other at the sealing part 15 in order to take out the absorbent article 1.

[0108] Therefore, for a structure that does not cause the packaging sheet 10 to break when the packaging sheets 10 are peeled from each other, the relationship between the tensile strength and the sealing strength of the sealing part was examined. In addition, in this examination, measurement was performed at room temperature using a tensile testing machine of TENSILON. As the measurement conditions, for the packaging sheet 10, a 25-mm width including the sealing part 15 (sealing width: 6 mm) was cut out in the long side direction of the packaging sheet 10, and the sealing part of the cut sample was stretched in the long side direction of the packaging sheet 10 to measure the tensile strength. The tensile speed at this time was set to 100 mm / sec, and the interval between the jigs was set to 10 mm. And the maximum point load (N / measurement width) was set as the strength of the sealing part 15.

[0109] [Table 2]

[0110]

[0111] As shown in Table 2, as Example 1, crepe paper with a basis weight of 18 gsm (manufactured by Oji Paper Co., Ltd.) was used. In addition, as Comparative Example 1, Unryu paper with a basis weight of 17 gsm (manufactured by Marubishi Pulp & Paper Technology Co., Ltd.) was used. Further, as Comparative Example 2, chemical fiber paper PM with a basis weight of 14 gsm (manufactured by Marubishi Pulp & Paper Technology Co., Ltd.) was used. As a result of inspecting these samples, in any of the paper of Example 1 and the papers of Comparative Examples 1 and 2, the sealing strength at the sealing portion 15 was smaller than the tensile strength of the packaging sheet 10.

[0112] From this, it can be understood that as long as the sealing strength at the sealing portion 15 is smaller than the tensile strength of the packaging sheet 10, when the packaging sheet 10 is peeled off at the sealing portion 15 in order to take out the absorbent article 1, the packaging sheet 10 is not easily broken.

[0113] As described above, the present invention has been described based on the embodiments, but the present invention is not limited to these embodiments. Within the scope described in the claims, the above embodiments can be variously changed, modified, replaced, added, deleted, combined, etc., and these also belong to the technical scope of the present invention. In addition, the above components can be arbitrarily combined.

[0114] This application claims the priority of Japanese Patent Application No. 2023-055944 filed on March 30, 2023, and incorporates the entire content thereof herein.

[0115] Explanation of reference numerals

[0116] 1 Absorbent article

[0117] 3 Topsheet

[0118] 4 Absorbent body

[0119] 7 Side sheets

[0120] 10 Packaging sheet

[0121] 11 One end in the long side direction

[0122] 12 The other end in the long side direction

[0123] 15 Sealing portion

[0124] 15a Crimping portion

[0125] 30 Adhesive tape

[0126] 31 Base portion

[0127] 32 Front end portion

[0128] 41 Colored area

[0129] 41a Coated area

[0130] 41b Non-coated area

[0131] 42 Non-colored area

[0132] 100 Individually packaged absorbent article

[0133] D1 Long side direction of the packaging sheet

[0134] D2 Short side direction of the packaging sheet

[0135] F1 First folding line

[0136] F2 Second folding line

[0137] R1 First area

[0138] R2 Second area

[0139] R3 Third area.

Claims

1. A packaging sheet, which is a paper-based packaging sheet that is transported in the fiber direction while being printed on the surface, and is used for individually packaging absorbent articles. Among them, The tensile strength of the packaging sheet in the fiber direction is 16 N or more and 25 N or less. When the tensile strength of the packaging sheet in the fiber direction before being printed is set as X, and the ratio of the area of at least one of the ink for the printing and the hot melt adhesive for bonding the packaging sheets to each other to the total area of the packaging sheet is set as Y, it satisfies 8.45 ≤ X × (1 - Y / 100). Among them, the unit of X is N, and the unit of Y is %.

2. The packaging sheet according to claim 1, Among them, The MMD of the surface where the printing is performed is 0.050 or less.

3. The packaging sheet according to claim 1 or 2, Among them, The basis weight of the paper is 30 gsm or less.

4. An individually packaged absorbent article, which is an individually packaged absorbent article formed by individually packaging the absorbent article with the packaging sheet according to claim 1 or 2. Among them, The packaging sheet individually packages the absorbent article by folding and sealing the edge portion. The sealing strength at the edge portion is less than the tensile strength.

5. A method for manufacturing a packaging sheet, which is used for individually packaging absorbent articles, and the method for manufacturing the packaging sheet includes at least one of the following processes: A printing process of printing on the surface of the packaging sheet while transporting the packaging sheet in the fiber direction; and A coating process of coating a hot melt adhesive on the surface of the packaging sheet while transporting the packaging sheet in the fiber direction. The tensile strength of the packaging sheet in the fiber direction is 16 N or more and 25 N or less. When the tensile strength of the packaging sheet in the fiber direction before being printed is set as X, and the ratio of the area of at least one of the ink for the printing and the hot melt adhesive to the total area of the packaging sheet is set as Y, it satisfies 8.45 ≤ X × (1 - Y / 100). Among them, The unit of X is N, and the unit of Y is %.

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