Packaging bags and sheet packaging

Abstract

The packaging bag of the present invention is a packaging bag that contains a sheet laminate made of a plurality of sheets, wherein the density of the sheet laminate is 0.09 g / cm³ or more and 0.50 g / cm³ or less; the packaging bag is made of a substrate containing paper components, wherein the first static friction coefficient of the inner surface of the substrate disposed on the inner side of the packaging bag is 0.25 or more and 0.5 or less; the second static friction coefficient of the outer surface of the substrate disposed on the outer side of the packaging bag is 0.3 or more and 0.65 or less; and the ratio of the first static friction coefficient to the second static friction coefficient is 0.5 or more and 0.9 or less.

Description

Packaging bags and sheet packaging This invention relates to a packaging bag and a sheet packaging body. Sheet packaging containing sheets of tissue paper, toilet paper, etc., is distributed and used in a state where multiple sheets are contained in a resin film packaging bag (e.g., Patent Documents 1, 2). In recent years, from the perspective of CO... Based on the viewpoint of curbing environmental burdens such as global warming and marine pollution such as microplastics, efforts are being made to actively change the packaging bags used in sheet packaging from resin to paper to reduce the amount of resin used in packaging bags. [Prior Art Documents] (Patent Documents) Patent Document 1: Japanese Patent Application Publication No. 2008-183034 Patent Document 2: Japanese Patent Application Publication No. 2018-177364 [Problem to be solved by the invention] However, compared with resin packaging bags, paper packaging bags are less flexible, so when there are opening holes, the holes are not easy to tear and thus the packaging is not easy to open. The problem with this invention is to provide an easy-to-open paper packaging bag. [Technical Means for Solving the Problem] One aspect of the packaging bag of the present invention is a packaging bag that contains a sheet laminate made of multiple sheets, wherein the density of the sheet laminate is 0.09 g / cm³. 3 Above and 0.50 g / cm 3 The aforementioned packaging bag is made of a substrate containing paper components, and the first static friction coefficient of the inner surface of the substrate disposed on the inner side of the aforementioned packaging bag is 0.25 or more and 0.5 or less; the second static friction coefficient of the outer surface of the substrate disposed on the outer side of the aforementioned packaging bag is 0.3 or more and 0.65 or less; and the ratio of the aforementioned first static friction coefficient to the aforementioned second static friction coefficient is 0.5 or more and 0.9 or less. [Effects of the Invention] According to one aspect of the present invention, an easy-to-open paper packaging bag can be provided. <Packaging Body> Embodiments of the present invention will be described in detail with reference to the accompanying drawings. In each drawing, common parts may be given the same symbols and their descriptions omitted. Also, in each drawing, the proportions of various parts may differ from the actual dimensions. Furthermore, in each drawing, a 3D orthogonal coordinate system with three axes (X, Y, and Z) is used, with the long side of the packaging bag designated as the X-axis, the width as the Y-axis, and the height (vertical or thickness direction) as the Z-axis. Figure 1 is a diagram showing a sheet package containing a sheet material in a packaging bag according to an embodiment. Figure 2 is a diagram showing the sheet material contained in a packaging bag according to an embodiment. Figures 3, 4, 5, 6, 7, and 8 are views of the sheet package of Figure 1 viewed from the top side, bottom side, front side, back side, left side, and right side, respectively. The sheet packaging body 100, as shown in Figures 1 and 2, includes a packaging bag 10 and a sheet laminate 20 (sheet S). The sheet packaging body 100 is an example of a sheet packaging body according to this embodiment. The packaging bag 10 is an example of a packaging bag constituting a sheet packaging body according to this embodiment. The sheet laminate 20 is an example of a sheet laminate contained within a packaging bag according to this embodiment. As shown in FIG. 2, a plurality of laminated sheets S (sheet laminate 20) are contained in the packaging bag 10. The sheet laminate 20 is contained in the packaging bag 10 such that the lamination direction (SD direction) of the sheet S is aligned with the height direction (Z direction). The sheet laminate 20 is configured such that the sheet S is pulled out one group at a time through the extraction outlet (opening OP) formed on the packaging bag 10 (described later) (see FIG. 11). There are no particular restrictions on the shape of the sheet stack 20. For example, it can be a shape in which sheets S in a folded state are stacked, a shape in which sheets S in a folded state are stacked with each other (so-called extractable sheet stack), or a shape in which multiple sheets S are stacked simply. Furthermore, the dimensions of the sheet S (sheet laminate 20) can be set such that, for example, when the sheet S is folded, the length L2 in the long side direction (X direction) of the packaging bag 10 is 150-250 mm, the width W2 in the width direction (Y direction) orthogonal to the long side direction (X direction) of the packaging bag 10 is 70-150 mm, and the height H2 in the height direction (Z direction) is 20-100 mm (see Figures 2 and 3). This sheet laminate can be manufactured, for example, by a rotary or multi-stand interfolder. The density of the sheet laminate is 0.09 g / cm³. 3 Above and 0.50 g / cm 3 The preferred value is 0.13 g / cm³. 3 Above and 0.40 g / cm 3 The preferred value is 0.15 g / cm³. 3 Above and 0.30 g / cm 3 The density of the sheet laminate is determined according to JIS P 8118 (2014). The form of sheet S is not particularly limited; for example, it can be used as toilet paper, kitchen paper, toilet paper, or similar tissues. These toilet papers also include those containing moisturizing ingredients (e.g., moisturizing toilet paper). Furthermore, the application of sheet S is not particularly limited, and it can be used for industrial, household, or portable purposes. Of these, sheet S in this embodiment is preferably a tissue suitable for household or portable use. The number of layers of sheet S is not particularly limited; it can be one or more layers, but is preferably one or two layers (two sheets overlapping). Furthermore, the shape of sheet S is not particularly limited; for example, it is preferably a two-layer sheet in a folded state with a rectangular (rectangular, square, etc.) outline. The material of sheet S is not particularly limited; for example, sheets of paper, non-woven fabric, or cloth can be used, but paper (paper sheet) is preferred. Furthermore, when sheet S is a paper sheet, a base paper with pulp as the main raw material is used. The pulp composition can use a known composition for paper sheets. For example, the pulp mixing ratio can be set to 50% by mass or more, preferably 90% by mass or more, and more preferably 100% by mass. Furthermore, there are no particular limitations on the pulp composition in the sheet S (paper sheet). For example, softwood pulps such as NBKP (needle-leaved tree bleached kraft pulp) and NUKP (needle-leaved tree unbleached kraft pulp), and hardwood pulps such as LBKP (broad-leaved tree bleached hardwood kraft pulp) and LUKP (broad-leaved tree unbleached hardwood kraft pulp) can be used in any proportion. Furthermore, in sheet S (paper sheet), the ratio of hardwood pulp to softwood pulp is not particularly limited, but is preferably 10:90 to 80:20, and more preferably a pulp composition with a higher proportion of softwood pulp to hardwood pulp. Also, waste paper pulp may be used in the pulp contained in sheet S (paper sheet). The basis weight of sheet S is not specifically limited; in the case of paper, it corresponds to a layer count of 5 g / m². 2 Above and 80g / m 2 The preferred value is 10g / m³. 2 Above and 60g / m 2 The following is preferred: 10g / m 2 Above and 45g / m 2 Furthermore, in the case of nonwoven fabrics, a g / m² of 20 g / m² is desirable. 2 Above and 100g / m 2 The following applies. Additionally, the basis weight is determined according to JIS P 8124 (2011). Furthermore, the thickness of the sheet S (paper sheet) is not particularly limited, and the paper thickness can be measured under conditions specified in JIS P 8111 (1998). For example, when the sheet S is paper, the thickness of each two layers is 50 μm or more and 600 μm or less, preferably 60 μm or more and 500 μm or less, and more preferably 130 μm or more and 400 μm or less. Alternatively, embossing can be applied to sheet S (paper sheet). This embossing process can be performed using conventional embossing methods. The shape of the packaging bag 10 is not particularly limited. In this embodiment, the packaging bag 10, when containing the sheet S (sheet laminate 20), has a top surface 11, a bottom surface 12, a side surface 13, a side surface 14, a short side surface 15, and a short side surface 16. Furthermore, in the packaging bag 10, the top surface 11 and the bottom surface 12 face each other in the vertical direction (Z direction), the side surface 13 and the side surface 14 face each other in the width direction (Y direction), and the short side surface 15 and the short side surface 16 face each other in the long side direction (X direction). Also, the short side surfaces 15 and 16 are continuous on any one of the top surface 11, the bottom surface 12, the side surface 13, and the side surface 14 (Figs. 1, 3-8). The dimensions of the packaging bag 10 are not particularly limited. For example, the length L1 of the packaging bag 10 in the long side direction (X direction) can be 150 to 250 mm, the width W1 in the width direction (Y direction) orthogonal to the long side direction (X direction) of the packaging bag 10 can be 70 to 150 mm, and the height H1 in the height direction (Z direction) can be 20 to 100 mm (Figures 1 and 3). In addition, the dimensions of the packaging bag 10 indicate the dimensions in which the sheet laminate 20 can be housed in the packaging bag 10 (Figures 1 and 2). On the top surface 11, the top surface 11 side of the short side surface 15, and the top surface 11 side of the short side surface 16 of the packaging bag 10, there are openings extending in the long side direction (X direction) of the packaging bag 10. Specifically, the openings are formed using a slit line 30 for opening. The slit line 30 for opening is a slit line in which the slit portion C and the connecting portion T (the part between the two slit portions C, where there is no cut) are alternately arranged, and if the connecting portion T breaks, the slit portions C on both sides become continuous cuts (Figs. 1, 3, 7, and 8). In this embodiment, the opening cut line 30 forms a straight eyelet M with the cutting portion C and the connecting portion T arranged alternately (Figs. 1, 3, 7, and 8). The ratio of the connecting portion T to the cutting portion C of the opening cut line 30 (eyelet) is arbitrary, for example, it can be set to 1:1 to 1:7, preferably 1:1.3 to 1:5, and more preferably 1:1.5 to 1:3. In the packaging bag 10 of this embodiment, an opening (opening OP) for the sheet S to be pulled out is formed on the top surface 11 of the packaging bag 10 by the opening cut line 30 (hole M) (Fig. 1, Fig. 10). Furthermore, the opening (opening cut line 30), in the examples shown in Figures 1, 3, 7, and 8, is a shape that extends continuously from the top surface 11 to the top surface 11 side of the short side 15 and the top surface 11 side of the short side 16, but it is not limited to this shape. Other shapes of the opening cut line 30 may include a shape that extends from the edge of the short side 15 side of the top surface 11 to the edge of the short side 16 side of the top surface 11 (not shown), or a shape that extends continuously from the edge of the short side 15 side of the top surface 11 to the edge of the short side 16 side of the top surface 11 (not shown). Furthermore, the method of manufacturing the opening cut line 30 is arbitrary. For example, although not shown, the substrate BS of the packaging bag 10 described later can be arranged between the needle and the platform, and the front end of the needle can be pierced towards the groove of the platform to form the opening cut line 30. Ventilation holes (not shown) can also be formed in the packaging bag 10. These ventilation holes function as air vents for the packaging bag 10. The location of the ventilation holes is not particularly limited; in this embodiment, ventilation holes can be provided on the sides 13, 14 and the short sides 15, 16 of the packaging bag 10. The number of ventilation holes is not particularly limited. Furthermore, the shape of the ventilation holes is not particularly limited; for example, they may be circular when viewed from above. Moreover, the size of the ventilation holes is not particularly limited; for example, a diameter of 2 mm. Furthermore, the method for making the vent is arbitrary. For example, similar to the aforementioned opening cut line 30, the substrate BS of the packaging bag 10 can be placed between the needle and the platform, and the tip of the needle can be pierced towards the groove of the platform to form a vent. Alternatively, the vent can be formed on a platform where no groove is provided. The packaging bag 10 is provided with such ventilation holes so that the packaging bag is not easily broken when the sheet packaging body 100 is stored and transported. The packaging form of the packaging bag 10 is not particularly limited. For example, it can be a packaging form in which the substrate BS of the packaging bag 10 is processed into a cylindrical shape and the open end of the cylindrical substrate BS is sealed (pillow-type packaging bag), or a packaging form in which the two ends of the cylindrical packaging bag 10 are folded and sealed (caramel packaging bag), or a combination of these packaging forms. In addition, in the case of a pillow-type packaging bag, the cylindrical substrate BS can also be folded into a gusseted shape. In this embodiment, the packaging bag 10 is configured as a pillow-type packaging bag having at least one sealing part. Specifically, sealing parts (end seals) 40 and 50 are formed on the short side surfaces 15 and 16 of the packaging bag 10, and a sealing part (bottom seal) 60 is formed on the bottom surface 12 of the packaging bag 10, and the sheet S (sheet laminate 20) is pillow-type packaged. In the packaging bag 10 of this embodiment, sealing portions 40, 50, and 60 are heat-fused together. Here, heat-fusion means heating a portion of the substrate BS to fuse portions of the packaging bag sheet together. Specifically, sealing portions 40, 50, and 60 are heat-fused together with the inner layer (resin layer) 10B of the substrate BS (described later) disposed inside the packaging bag 10. In the packaging bag 10, the joint spacing of the sealing part 40, the joint spacing of the sealing part 50, and the joint spacing of the sealing part 60 are preferably 0.5 mm or more and 2 mm or less, more preferably 0.8 mm or more and 1.8 mm or less, and even more preferably 1.0 mm or more and 1.5 mm or less. Here, the joint spacing refers to the interval in a specified direction (for the sealing portions 40, 50, 60, the width direction (Y direction) of the packaging bag 10; for the sealing portion 60, the length direction (X direction) of the packaging bag 10 when viewed from one side (e.g., the bottom surface 12 side of the packaging bag 10). In this embodiment, as described above, the joint spacing of the sealing portions (sealing portions 40, 50, 60) is set to 0.5 mm or more and 2 mm or less, thereby improving the adhesion function of the inner layer (resin layer) 10B provided in the base layer (paper layer) 10A described later, so as to obtain a packaging bag 10 (pillow-type packaging bag) with higher sealing performance. Packaging bag 10 is made of a base material BS containing paper components. Here, the paper component is a pulp made by bonding plant fibers. The pulp composition in the paper component is not limited; for example, the ratio of hardwood pulp to softwood pulp is 0:100 to 70:30, and preferably a pulp composition with a higher proportion of softwood pulp than hardwood pulp. Furthermore, waste paper pulp may also be used in the pulp. The substrate BS constituting the packaging bag 10 of the first embodiment is composed of a base layer 10A, an inner layer 10B, and an outer layer 10C. The substrate BS in the first embodiment is configured as a three-layer structure with an inner layer 10B and an outer layer 10C in each area layer of the paper layer 10A (Fig. 9). The base layer 10A constitutes the base of the substrate BS. Furthermore, the base layer 10A is composed of a paper layer containing the aforementioned paper components. That is, the substrate BS includes the base layer 10A, which contains paper components. The material of the paper component included in the base layer (paper layer) 10A is not particularly limited; for example, it can be formed with kraft paper or rayon paper. Here, kraft paper refers to paper made from kraft pulp. Rayon paper, on the other hand, is paper made by mixing rayon fibers, which are chemically synthesized from wood pulp, into kraft pulp. Furthermore, from the viewpoint of balancing the softness and strength of the packaging bag 10, the optimal mixing ratio of rayon pulp is 20% or less by weight. There is no limit to the basis weight of the 10A base layer (paper layer), but 10 g / m² is preferred. 2 Above and 70g / m 2 The following is preferred: 15g / m 2 Above and 60g / m 2 The following is a further preferred value: 20g / m 2 Above and 50g / m 2 The following applies. Additionally, the basis weight is determined according to JIS P 8124 (2011). The thickness of the base layer (paper layer) 10A is not particularly limited, but is preferably 20 μm or more and 300 μm or less, more preferably 30 μm or more and 200 μm or less, and even more preferably 40 μm or more and 180 μm or less. Furthermore, the thickness is measured according to the specifications of JIS P 8118 (2014). There is no particular limitation on the tensile strength of the base layer (paper layer) 10A. For example, the longitudinal direction of the fiber (production line direction or MD direction) is above 500cN / m and below 20000cN / m, preferably above 1000cN / m and below 15000cN / m, and even more preferably above 1500cN / m and below 12000cN / m. Furthermore, the transverse fiber strength (the direction orthogonal to the production line direction or the CD direction) is 100 cN / m or more and 10,000 cN / m or less, preferably 300 cN / m or more and 7,000 cN / m or less, and more preferably 500 cN / m or more and 4,000 cN / m or less. Additionally, the tensile strength is measured according to JIS P 8113 (2006). The elongation of the base layer (paper layer) 10A is not particularly limited. For example, the elongation in the longitudinal direction (MD direction) of the fibers is 0.5% or more and 30% or less, preferably 1% or more and 25% or less, and more preferably 2% or more and 20% or less. Furthermore, the elongation in the transverse direction (CD direction) of the fibers is 0.5% or more and 20% or less, preferably 1% or more and 10% or less, and more preferably 2% or more and 5% or less. Additionally, the elongation is measured according to the provisions of JIS P 8113 (2006). There is no particular limitation on the tensile strength of the base layer (paper layer) 10A. For example, the longitudinal direction (MD direction) of the fiber is 50mN or more and 500mN or less, preferably 80mN or more and 480mN or less, and even more preferably 100mN or more and 450mN or less. Furthermore, the transverse (CD) strength of the fiber is 50 mN or more and 1000 mN or less, preferably 80 mN or more and 900 mN or less, and even more preferably 100 mN or more and 800 mN or less. Additionally, the tensile strength is determined according to JIS P 8116 (2000). The inner layer 10B, laminated on one side of the base layer (paper layer) 10A, is composed of a resin layer containing thermoplastic resin. The inner layer (resin layer) 10B is disposed inside the packaging bag 10. Here, the inside of the packaging bag 10 is the side of the sheet S contained in the packaging bag 10 that contacts the substrate BS of the packaging bag 10 (that is, the side of the packaging bag 10 where the sheet S is contained or the side of the substrate BS where the inner layer 10B is formed). In the inner layer 10B, an inner surface IS of a substrate BS disposed on the inner side of the packaging bag 10 (on the side of the packaging bag 10 where the sheet S is contained) is formed. In addition, the inner surface IS of the substrate BS disposed on the inner side of the packaging bag 10 corresponds to the side of the substrate BS that contacts the sheet S contained in the packaging bag 10 (that is, the side of the substrate BS where the inner layer 10B is formed, or the side opposite to the side of the substrate BS where the outer layer 10C is formed). The material of the thermoplastic resin contained in the inner layer (resin layer) 10B is not particularly limited, but low-density polyethylene is preferred. Alternatively, the low-density polyethylene can be either low-density polyethylene (LDPE) or linear low-density polyethylene (L-DPE). The thickness of the inner layer (resin layer) 10B is not particularly limited, but it is preferably 5 μm or more and 40 μm or less, more preferably 7 μm or more and 35 μm or less, and even more preferably 9 μm or more and 30 μm or less. Furthermore, the thickness is measured according to the specifications of JIS P 8118 (2014). The inner layer (resin layer) 10B contains a slip agent in its thermoplastic resin. Here, the slip agent is an additive that reduces the coefficient of friction of the surface (inner surface) of the inner layer 10B. In this embodiment, the slip agent is added to the thermoplastic resin contained in the inner layer (resin layer) 10B, but it can also be applied to the inner surface IS of the substrate BS. The composition of the slip agent is not particularly limited; for example, ethylene homopolymers, amino fatty acids, and vegetable oils can be used as the main components. Furthermore, there is no particular limitation on the amount of slip agent containing thermoplastic resins. In addition to the main components, the slip agent may also contain additives for purposes such as maintaining the stability of the slip agent. In this embodiment, the substrate BS of the packaging bag 10 includes a base layer 10A containing paper components, and an inner layer 10B deposited on one side of the base layer 10A and disposed inside the packaging bag 10. The inner layer 10B contains a thermoplastic resin containing a slip agent, thereby reducing the friction (static coefficient of friction) between the substrate BS and the sheet S. Therefore, the substrate BS can easily slide against the sheet S, making it easy to open even when the perforation M is provided in the paper packaging bag 10 (Figures 1 and 10). The outer layer (printed layer) 10C is disposed on the other side of the paper layer 10A and is configured as a printed layer printed on the surface of the packaging bag. The outer layer (printed layer) 10C is disposed on the outside of the packaging bag 10. Here, the outside of the packaging bag 10 refers to the side of the substrate BS of the packaging bag 10 that does not contact the sheet S contained in the packaging bag 10 (that is, the opposite side to the side in the packaging bag 10 where the sheet S is contained or the side of the substrate BS where the inner layer 10B is formed). In the outer layer (printed layer) 10C, there is an outer surface OS of the substrate BS disposed on the outside of the packaging bag 10 (on the side of the packaging bag 10 opposite to the side containing the sheet S). In addition, the outer surface OS of the substrate BS disposed on the outside of the packaging bag 10 corresponds to the side that does not contact the sheet S contained in the packaging bag 10 (that is, the side of the substrate BS on which the outer layer 10C is formed or the side of the substrate BS opposite to the side on which the inner layer 10B is formed). The outer layer (printed layer) 10C contains an anti-slip agent. Here, the anti-slip agent is an additive that increases the coefficient of friction of the surface (outer surface) of the outer layer 10C. In this type, the anti-slip agent is applied to the outer surface OS of the substrate BS, but it may also be contained in the outer layer (printed layer) 10C. There are no particular limitations on the composition of anti-slip agents; for example, colorless inks (synthetic resins) and oil-based primers can be used as the main components. Furthermore, there are no particular limitations on the amount of anti-slip agent used for the outer layer (printed layer) 10C. In addition to the main components, anti-slip agents may also contain additives and solvents for purposes such as maintaining the stability of the anti-slip agent. In this embodiment, the substrate BS of the packaging bag 10 includes a base layer 10A containing paper components, and an outer layer 10C, which is laminated on the other side of the base layer 10A and disposed on the outside of the packaging bag 10. The outer layer 10C contains an anti-slip agent, thereby increasing the friction between the outer layer 10C of the substrate BS and the fingers (hereinafter referred to as fingers) of a person touching the outer layer 10C of the substrate BS. This makes it less likely for fingers touching the substrate BS to slide on it, while the substrate BS easily slides on the sheet laminate 20 (sheet S). Therefore, when the sheet S is placed in the paper packaging bag 10, the sheet S is easy to tear, and even the paper packaging bag 10 can be easily opened (Figs. 1 and 10). In this embodiment, the paper content in the packaging bag 10 (substrate BS) is 50% or more. There are no other restrictions on the basis weight of packaging bag 10 (substrate BS), but it is preferably 20 g / m³. 2 Above and 100g / m 2 The following is preferred: 25g / m 2 Above and 70g / m 2 The following is a further preferred value: 30g / m 2 Above and 60g / m 2 The following applies. Additionally, the basis weight is determined according to JIS P 8124 (2011). The thickness (paper thickness) of the packaging bag 10 (substrate BS) is not particularly limited, but is preferably 25 μm or more and 350 μm or less, more preferably 30 μm or more and 250 μm or less, and even more preferably 45 μm or more and 200 μm or less. Furthermore, the thickness is measured according to the specifications in JIS P 8118 (2014). The tensile strength of the packaging bag 10 (substrate BS) is not particularly limited, but for example, the longitudinal direction (MD direction) of the fiber is above 1000cN / m and below 20000cN / m, preferably above 1500cN / m and below 18000cN / m, and even more preferably above 2000cN / m and below 15000cN / m. Furthermore, the transverse (CD) fiber strength is 500 cN / m or more and 10000 cN / m or less, preferably 1000 cN / m or more and 8000 cN / m or less, and even more preferably 1500 cN / m or more and 5000 cN / m or less. Additionally, the tensile strength is measured according to JIS P 8113 (2006). The elongation of the packaging bag 10 (substrate BS) is not particularly limited. For example, the elongation in the longitudinal direction (MD direction) is 0.5% or more and 30% or less, preferably 1% or more and 25% or less, and more preferably 2% or more and 20% or less. Similarly, the elongation in the transverse direction (CD direction) is 0.5% or more and 20% or less, preferably 1% or more and 10% or less, and more preferably 1.5% or more and 5% or less. Furthermore, the elongation is measured according to JIS P 8113 (2016). The tensile strength of the packaging bag 10 is not particularly limited. For example, the longitudinal direction (MD direction) of the fiber is above 50mN and below 500mN, preferably above 80mN and below 450mN, and even more preferably above 100mN and below 400mN. Furthermore, the transverse (CD) strength of the fiber is 200 mN or more and 1000 mN or less, preferably 250 mN or more and 900 mN or less, and even more preferably 300 mN or more and 800 mN or less. Additionally, the tensile strength is determined according to JIS P 8116 (2000). The Taber stiffness of the packaging bag 10 (substrate BS) is not particularly limited. For example, the longitudinal direction (MD direction) of the fiber is above 0.01mN / m and below 0.20mN / m, preferably above 0.02mN / m and below 0.17mN / m, and even more preferably above 0.03mN / m and below 0.15mN / m. Furthermore, the transverse (CD) fiber strength is 0.001 mN / m or more and 0.2 mN / m or less, preferably 0.01 mN / m or more and 0.15 mN / m or less, and even more preferably 0.02 mN / m or more and 0.13 mN / m or less. Additionally, the Taber stiffness is measured according to JIS P 8125 (2000). In the packaging bag 10 of this embodiment, the inner surface IS of the substrate BS disposed on the inner side of the packaging bag 10 (the inner surface IS of the side of the substrate BS on which the inner layer 10B is formed) has a first static friction coefficient A. The first static friction coefficient A is 0.25 or more and 0.5 or less, preferably 0.27 or more and 0.48 or less, and more preferably 0.3 or more and 0.45 or less. In this specification, the static friction coefficient is the ratio of the frictional force generated between the contact surfaces of two objects when they are not in relative motion to the force acting at a right angle to the contact surfaces. The static friction coefficient is determined according to the level method specified in JIS P 8147 (2010). Furthermore, the first static friction coefficient A can be defined as the friction coefficient between the inner surface IS of the substrate BS and the sheet S (basis weight 33 g / m²). 2 The static friction coefficient A1 generated between the paper towels. At this time, the static friction coefficient A1 is 0.3 or more and 0.5 or less, preferably 0.33 or more and 0.48 or less, and more preferably 0.35 or more and 0.45 or less. The first static friction coefficient A can be defined as the static friction coefficient A2 generated between the inner surface IS of the substrate BS and the aluminum foil (thickness of 20 μm). In this case, the static friction coefficient A2 is 0.25 or more and 0.5 or less, preferably 0.27 or more and 0.48 or less, and more preferably 0.3 or more and 0.45 or less. Furthermore, the outer surface OS of the substrate BS disposed on the outside of the packaging bag 10 (the outer surface OS of the side of the substrate BS on which the outer layer 10C is formed) has a second static friction coefficient B. The second static friction coefficient B is 0.3 or more and 0.65 or less, preferably 0.35 or more and 0.63 or less, and more preferably 0.4 or more and 0.6 or less. The second static friction coefficient B can be defined as the coefficient of friction between the outer surface OS of the substrate BS and the sheet S (based on a weight of 33 g / m²). 2 The static friction coefficient B1 generated between the paper towels. At this time, the static friction coefficient B1 is 0.5 or more and 0.65 or less, preferably 0.52 or more and 0.6 or less, and more preferably 0.54 or more and 0.57 or less. Furthermore, the second static friction coefficient B can be defined as the static friction coefficient B2 generated between the outer surface OS of the substrate BS and the aluminum foil (thickness of 20 μm). In this case, the static friction coefficient B2 is 0.3 or more and 0.54 or less, preferably 0.35 or more and 0.53 or less, and more preferably 0.4 or more and 0.52 or less. In the packaging bag 10 of this embodiment, the ratio of the first static friction coefficient A to the second static friction coefficient B is 0.5 or more and 0.9 or less, preferably 0.55 or more and 0.89 or less, and more preferably 0.6 or more and 0.87 or less. Here, the ratio of the first static friction coefficient A to the second static friction coefficient B represents the ratio of the first static friction coefficient A to the second static friction coefficient B. Furthermore, when the first static friction coefficient A is static friction coefficient A1 and the second static friction coefficient B is static friction coefficient B1, the ratio of static friction coefficient A1 to static friction coefficient B1 is 0.6 or more and 0.85 or less, preferably 0.65 or more and 0.83 or less, and more preferably 0.7 or more and 0.8 or less. Furthermore, when the first static friction coefficient A is static friction coefficient A2 and the second static friction coefficient B is static friction coefficient B2, the ratio of static friction coefficient A2 to static friction coefficient B2 is 0.5 or more and 0.9 or less, preferably 0.55 or more and 0.89 or less, and more preferably 0.6 or more and 0.87 or less. Alternatively, the substrate BS with this static friction coefficient can be formed all over the entire surface of the packaging bag 10, or it can be formed only on the surface where the holes M are formed (e.g., the top surface 11 of the packaging bag). In this embodiment, this configuration results in a density of 0.09 g / cm³. 3 Above and 0.50 g / cm 3 In the following sheet laminate 20, the first static friction coefficient A of the inner surface IS of the substrate is 0.25 or more and 0.5 or less, and the second static friction coefficient B of the outer surface OS of the substrate is 0.3 or more and 0.65 or less. The ratio of the first static friction coefficient A to the second static friction coefficient B is 0.5 or more and 0.9 or less. This generates a certain amount of friction on the inner surface IS of the substrate BS constituting the packaging bag 10, and generates a greater friction force on the outer surface OS of the substrate BS than the friction force generated on the inner surface IS of the substrate BS. Therefore, the frictional force generated on the inner surface IS of the substrate BS, taking the same sheet laminate 20 as a reference, is relatively smaller on the inner surface IS and relatively larger on the outer surface OS (Fig. 9). In this configuration, fingers touching the substrate BS are less likely to slide on the substrate BS, so when the eyelet M is provided in the paper packaging bag 10, the eyelet M is easy to open, and even the paper packaging bag 10 can be easily opened (Figs. 1 and 10). Furthermore, in this embodiment, the first static friction coefficient A of the inner surface IS of the substrate BS disposed on the inner side of the packaging bag 10 is 0.25 or more and 0.5 or less. As a result, the inner surface IS of the substrate BS containing paper components becomes easy to slide against the sheet S, which further makes it easier to open the holes M provided on the paper packaging bag 10, and further makes it easier to open the packaging bag 10 (Figs. 1 and 10). Furthermore, the ratio of the first static friction coefficient A to the second static friction coefficient B is 0.5 or more and 0.9 or less, thereby increasing the difference between the friction coefficient on the inner surface IS side of the substrate BS of the sheet S contained in the packaging bag 10 and the friction coefficient on the outer surface OS side of the substrate BS. Therefore, the perforations M provided in the paper packaging bag 10 are easily opened, thus making it easier to open the packaging bag 10. Furthermore, in the paper packaging bag 10, from the viewpoint of improving openability, the difference between the first static friction coefficient A and the second static friction coefficient B can be set as large as possible. On the other hand, if the second static friction coefficient B is too large compared to the first static friction coefficient A, the holes M provided in the paper packaging bag 10 may tear before the packaging bag 10 is opened (for example, during the manufacturing, distribution, and storage of the sheet packaging body 100 using the packaging bag 10). Therefore, in this embodiment, the second static friction coefficient B is set to 0.3 or more and 0.65 or less. This adjusts the second static friction coefficient B in such a way that the outer surface OS of the substrate BS does not become excessively slippery. Thus, the openingability of the packaging bag is not reduced and unexpected tearing of the packaging bag 10 is prevented. In the packaging bag 10 of this embodiment, the first static friction coefficient A and the second static friction coefficient B correspond to the static friction coefficients between the CD direction of the substrate BS and the MD direction of the sheet S. Furthermore, in this embodiment, the MD direction of the substrate BS corresponds to the long side direction (X direction) of the packaging bag 10; the CD direction of the substrate BS corresponds to the width direction (Y direction) of the packaging bag 10 (Figures 1, 3-8). Also, the MD direction of the sheet S corresponds to the width direction (Y direction) of the packaging bag 10 or the sheet laminate 20; the CD direction of the sheet S corresponds to the long side direction (X direction) of the packaging bag 10 or the sheet laminate 20 (Figures 1, 2). In this embodiment, the coefficient of static friction between the CD direction of the inner surface IS of the substrate and the MD direction of the sheet S is set as the first coefficient of static friction, thereby making the CD direction of the inner surface IS of the substrate easy to slide relative to the MD direction of the sheet S. Furthermore, the coefficient of static friction between the CD direction of the outer surface OS of the substrate and the MD direction of the sheet S is set as the second coefficient of static friction, thereby making the CD direction of the outer surface OS of the substrate less prone to sliding relative to a finger touching the substrate BS. Therefore, when sheet S is housed in packaging bag 10 with the MD direction of sheet S aligned with the CD direction of substrate BS, and the perforation M is formed in the MD direction of substrate BS, if the surface of packaging bag 10 with the perforation M is pressed with both thumbs and moved away in the CD direction of substrate BS, the perforation M will open. At this point, the perforation M can be easily opened with only a small amount of force, thus further facilitating the opening of packaging bag 10. In the packaging bag 10 of this embodiment, as described above, an opening cut line 30 (hole M) is formed on the top surface 11 of the packaging bag 10 along the MD direction of the substrate BS. In this embodiment, an opening cut line 30 (hole M) along the MD direction of the substrate BS is formed on the top surface 11 of the packaging bag 10. By simply pressing the top surface 11 of the packaging bag 10 with the thumbs of both hands and moving each thumb away in the CD direction of the substrate BS, the opening cut line 30 (hole M) is broken, so the packaging bag 10 can be opened easily. Furthermore, in this embodiment, the cleaving line 30 (hole M) for opening can form an opening (opening OP) for the sheet S formed on the top surface 11 of the packaging bag 10 (Figs. 1 and 10). Therefore, the sheet S can be removed from the top surface 11 of the packaging bag 10. In this embodiment, the opening slit line 30 (hole M) is formed along the MD direction of the substrate BS and the CD direction of the sheet S, and the static friction coefficient is measured in a direction orthogonal to the extension direction of the hole M (the CD direction of the substrate BS and the MD direction of the sheet S). However, the orientation of the sheet S and the substrate BS for measuring the static friction coefficient is not limited. For example, the opening slit line 30 (hole M) can also be formed along the CD direction of the substrate BS and the MD direction of the sheet S, and the static friction coefficient can be measured in a direction orthogonal to the extension direction of the hole M (the MD direction of the substrate BS and the CD direction of the sheet S). Furthermore, in this embodiment, the case where the sheet S is housed in the packaging bag 10 with the MD direction of the sheet S aligned with the CD direction of the substrate BS is described; however, the relationship between the MD direction of the sheet S and the CD direction of the substrate BS is not limited. That is, the direction in which the sheet S is housed in the packaging bag 10 is not limited. For example, the sheet S may also be housed in the packaging bag 10 with the MD direction of the sheet S aligned with the MD direction of the substrate BS. The sheet packaging 100 of this embodiment can use the aforementioned packaging bag 10. Specifically, the sheet packaging 100 has a packaging bag (the packaging bag of the first embodiment) 10 and a sheet S contained in the packaging bag 10 (Figures 1 and 2). The sheet packaging 100 of this embodiment is configured to house the sheet S within the aforementioned packaging bag 10, thereby achieving the same effect as the aforementioned packaging bag 10. That is, in the sheet packaging 100 of this embodiment, even if the packaging bag 10 constituting the sheet packaging 100 is made of paper, the perforations M provided in the paper packaging bag 10 can be easily torn open, and even the paper packaging bag 10 can be easily opened (Figs. 1 and 10). In this embodiment of the packaging bag 10, as described above, an inner layer (resin layer) 10B containing thermoplastic resin is disposed on one surface of a base layer (paper layer) 10A containing paper components, thereby making the texture of the packaging bag 10 softer. This suppresses the roughness of the packaging bag 10 and gives it the ability to adapt to deformation. Therefore, even when the material of the packaging bag is changed from resin to paper, a packaging bag 10 that is not easily broken during manufacturing and transportation can be provided. Furthermore, in this embodiment, an inner layer (resin layer) 10B is laminated on the base layer (paper layer) 10A, thereby setting the opening cut line 30 on the packaging bag 10 which is given deformation-following properties, so that the opening cut line 30 is easy to open. Furthermore, in this embodiment, the inner layer (resin layer) 10B disposed on one side of the base layer (paper layer) 10A contains a thermoplastic resin, thereby allowing the inner layer (resin layer) 10B to be heated when the packaging bag 10 is to be sealed (or closed) to obtain the function of the molten inner layer (resin layer) 10B as an adhesive (having adhesive function), so the packaging bag 10 is easy to seal. Furthermore, in this embodiment, the proportion of paper in the packaging bag 10 is more than 50%, making the amount of paper in the packaging bag 10 greater than the amount of resin, so that the paper in the packaging bag 10 can be recycled. Also, the amount of plastic used can be reduced, thus suppressing environmental impact. In this embodiment, as described above, the thickness of the inner layer (resin layer) 10B is set to 5 μm or more and 40 μm or less, thereby easily maintaining the paper content in the packaging bag at 50% or more. Furthermore, it can suppress the roughness of the packaging bag and maintain the adhesive function of the inner layer (resin layer) 10B when the packaging bag is sealed. In this embodiment, as described above, low-density polyethylene is used as the thermoplastic resin contained in the inner layer (resin layer) 10B, thereby suppressing the roughness of the packaging bag 10 and improving the adhesion performance of the inner layer (resin layer) 10B when the packaging bag 10 is sealed. In this embodiment, as described above, the packaging bag 10 is a pillow-type packaging bag, and at least one sealing portion is heat-fused together with the inner layer (resin layer) 10B disposed inside the packaging bag 10, thereby bonding the resin layers 10B together. This effectively utilizes the adhesive function of the inner layer (resin layer) 10B, thus obtaining a packaging bag 10 with high sealing performance. [Examples] The present invention will be further described in detail below using examples. The examples and comparative examples were evaluated by the following tests. [Test Subject] Prepare a sheet packaging body 100, which packs multiple sheets S (sheet laminates 20) in a paper packaging bag 10 in a pillow-type packaging manner as a test subject (Figs. 1 to 8). The packaging bag 10 is constructed from a base material BS; the base material BS is constructed from a base layer 10A, an inner layer 10B, and an outer layer 10C (Fig. 9). The inner layer 10B is made of low-density polyethylene (PE). The outer layer 10C is a printing layer produced by gravure. On the top surface 11 of the packaging bag 10, an opening cut line 30 (hole M) is formed, extending from the sealing portion 40 through the top surface 11 to the sealing portion 50 in the long side direction (MD direction) of the packaging bag 10. The ratio of the connecting portion T of the hole M to the cut portion C is set to 1:2 in the embodiment and comparative example. Sheet S, laminated in sheet 20, uses tissue paper 1 (product name "elleair tissue paper double (medium size)", manufactured by Daio Paper Corporation, double (2-ply), 200 sets (400 sheets), height H1: 70mm, length L1: 210mm, width (depth) W1: 115mm, basis weight 23g / m³. 2 Density 0.293 g / cm³ 3), Tissue Paper 2 (Product name: "elleair Paper Packaging Tissue Paper Eco-friendly Dry (Medium Size)", manufactured by Daio Paper Corporation, single (1-ply), 200 sheets, height H1: 67mm, length L1: 210mm, width (depth) W1: 115mm, basis weight 33g / m³ 2 Density 0.194 g / cm³ 3 ), and toilet paper (product name "elleair i:na (premium) toilet paper soft pack", manufactured by Daio Paper Corporation, double (2-ply), 150 packs (300 sheets), height H1: 43mm, length L1: 181mm, width (depth) W1: 103mm, basis weight 10.7g / m³). 2 Density 0.171 g / cm³ 3 ). [Weight per square meter] The weight per square meter (basic weight) of the substrate (full layer) BS and base layer 10A of the packaging bag 10 in the test subject (sheet packaging 100) was determined according to JIS P 8124 (2011). The unit of weight per square meter is g / m². 2 . [Paper Thickness] The paper thickness (full layer) BS and base layer 10A of the packaging bag 10 in the test subject (sheet packaging 100) was measured according to JIS P 8118 (2014) using an ISO paper thickness gauge (manufactured by CITIZEN, MEI-11). The unit of thickness is μm. [Tensile Strength] The tensile strength (mM) in the longitudinal direction (MD direction) and transverse direction (CD direction) of the substrate (full layer) BS and the base layer 10A of the packaging bag 10 in the test body (sheet packaging 100) was determined according to JIS P 8113 (2006) and using a TENSILON universal testing machine (manufactured by A&D Company, RTG-1210). [Elongation] The elongation (%) in the longitudinal (MD direction) and transverse (CD direction) directions of the substrate (full layer) BS and the base layer 10A of the packaging bag 10 in the test body (sheet packaging body 100) was determined according to JIS P 8113 (2006) and using a TENSILON universal testing machine (manufactured by A&D Company, RTG-1210). [Tearing Strength] The longitudinal (MD) and transverse (CD) tearing strength of the fibers were determined for the substrate (full layer) BS and the base layer 10A of the packaging bag 10 in the test body (sheet packaging 100) according to JIS P 8116 (2000) and using a tearing strength tester (Elmendorf tearing strength tester (digital display) manufactured by Kumagai Riki Kogyo Co., Ltd.). [Taber Stiffness] The Taber stiffness of the substrate (full layer) BS of the packaging bag 10 in the test subject (sheet packaging 100) was determined according to JIS P 8125 (2000). The Taber stiffness was determined using a Taber stiffness testing machine (manufactured by Toyo Seiki Co., Ltd.). [Static Friction Coefficient] The static friction coefficient is determined according to the horizontal method specified in JIS P 8147 (2010). The static friction coefficient is determined using a load cell tensile testing machine (Shimadzu Corporation, AGS-500B). Specifically, the static friction coefficient A1 is measured between the CD direction of the inner surface IS (inner layer 10B) of the substrate BS of the packaging bag 10 and the MD direction of the sheet S, and the static friction coefficient A2 is measured between the CD direction of the inner surface IS (inner layer 10B) of the substrate BS and the glossy surface of the aluminum foil (also known as aluminum foil paper). In addition, sheet S uses a basis weight of 33g / m². 2 The tissues (product name "elleair paper-wrapped tissues, eco-friendly dry single (medium size)", manufactured by Daio Paper Corporation, 200 sheets, height H1: 65mm, length L1: 210mm, width (depth) W1: 115mm). Furthermore, the static friction coefficient B1 between the CD direction of the outer surface OS (outer layer 10C) of the substrate BS of the packaging bag 10 and the MD direction of the sheet S, and the static friction coefficient B2 between the CD direction of the outer surface OS (outer layer 10C) of the substrate BS of the packaging bag 10 and the glossy surface of the aluminum foil (also known as aluminum foil paper) are measured. In addition, the aluminum foil used is 30cm wide, 7m long and 20μm thick (manufactured by UACJ Foil Co., Ltd., MyFoil (registered trademark)). In the determination of static friction coefficients A1, A2, B1, B2, the substrate BS is fixed to the horizontal plate side of the friction testing machine with the CD direction of the inner surface (inner layer 10B) as the surface side, and the sheet S is fixed to the weight side of the friction testing machine with the MD direction of the surface of the sheet S as the surface side. Furthermore, calculate the ratio of static friction coefficient A1 to static friction coefficient B1, and the ratio of static friction coefficient A2 to static friction coefficient B2. [Ease of Opening the Holes] The ease of opening the holes M (opening cut lines 30) on the top surface 11 of the packaging bag 10 formed in the test body (sheet packaging 100) was confirmed. Individual tests were conducted for cases where a single-layer type sheet S (web) was contained in the packaging bag 10, and for cases where a double-layer type tissue sheet was contained in the packaging bag 10. The evaluation of the ease of opening the holes on the sheet packaging 100 was based on the following criteria: when 10 users pressed the surface (top surface 11) with the holes M on the packaging bag 10 with their thumbs, moving their thumbs away in the CD direction of the substrate BS, a score of 5 (Excellent) was given if 0-2 users reported difficulty opening, 4 (Good) if 3-4 users reported difficulty opening, 3 (Fair) if 5-6 users reported difficulty opening, 2 (Poor) if 7-8 users reported difficulty opening, and 1 (Poor) if 9-10 users reported difficulty opening. The evaluation criteria are as follows. 5: Very easy to open; 4: Easy to open; 3: Can be opened; 2: Can be opened but not easy to open; 1: Cannot be opened. The following describes the embodiments and comparative examples. [Example 1] In the inner layer 10B of the substrate BS of the packaging bag 10, PE with added slip agent was used, and an anti-slip agent (primer) was applied to the outer layer 10C. The static friction coefficients A1, A2, B1, and B2 were 0.44, 0.31, 0.56, and 0.42, respectively. The ratio of static friction coefficient A1 to B1 was 0.786, and the ratio of static friction coefficient A2 to B2 was 0.738. Table 1 shows the conditions of the packaging bag 10, the conditions of the web, and the evaluation results. [Example 2] Except that the static friction coefficients A1, A2, B1, and B2 were 0.45, 0.44, 0.56, and 0.51, and the ratio of A1 to B1 was 0.804 and 0.863, the test specimens were prepared and evaluated in the same manner as in Example 1. Table 1 shows the conditions for the packaging bag 10, the conditions for the web, and the evaluation results. [Example 3] Except that the static friction coefficients A1, A2, B1, and B2 were 0.38, 0.31, 0.55, and 0.51, respectively, and the ratio of A1 to B1 was 0.691 and the ratio of A2 to B2 was 0.608, the test specimens were prepared and evaluated in the same manner as in Example 1. Table 1 shows the conditions of the packaging bag 10, the conditions of the web, and the evaluation results. [Comparative Example 1] Except that the static friction coefficients A1, A2, B1, and B2 were 0.53, 0.47, 0.51, and 0.50, respectively, and the ratio of A1 to B1 was 1.039 and 0.940, the test specimens were prepared and evaluated in the same manner as in Example 1. Table 1 shows the conditions of the packaging bag 10, the conditions of the web, and the evaluation results. [Table 1] Table 1 shows that the density of the sheet laminate is 0.171–0.293 g / cm³. 3 Test specimens with static friction coefficients A1 of 0.38–0.45, A2 of 0.31–0.44, B1 of 0.55–0.56, B2 of 0.42–0.51, a ratio of A1 to B1 of 0.691–0.804, and a ratio of A2 to B2 of 0.608–0.863 exhibited good ease of opening of the pores (Examples 1–3). In contrast, the test specimens with static friction coefficients A1 (0.53), A2 (0.47), B1 (0.51), B2 (0.50), A1 to B1 (1.039), and A2 to B2 (0.940) exhibited poor ease of opening the pores (Comparative Example 1). The above describes the embodiments of the present invention. However, the present invention is not limited to a specific embodiment, but can be modified and altered in various ways within the scope of the invention as described in the claims. The preferred embodiments of the present invention are described below. Regarding the first aspect of the present invention, a packaging bag is provided, which is a packaging bag for containing a sheet laminate made of a plurality of sheets, wherein the density of the sheet laminate is 0.09 g / cm³. 3 Above and 0.50 g / cm 3 The aforementioned packaging bag is made of a substrate containing paper components, and the first static friction coefficient of the inner surface of the substrate disposed on the inner side of the aforementioned packaging bag is 0.25 or more and 0.5 or less; the second static friction coefficient of the outer surface of the substrate disposed on the outer side of the aforementioned packaging bag is 0.3 or more and 0.65 or less; and the ratio of the aforementioned first static friction coefficient to the aforementioned second static friction coefficient is 0.5 or more and 0.9 or less. In this specification, the paper composition refers to a composition made by bonding plant fibers together. The density of the sheet laminate is the density measured according to JIS P 8118 (2014). The static friction coefficient represents the ratio of the frictional force generated between the contact surfaces of two objects in a state of no relative motion to the force acting at a right angle to the contact surfaces. The outer side of the packaging bag refers to the side of the packaging bag's substrate that does not contact the sheet housed within the packaging bag (i.e., the side opposite to the side where the sheet is housed within the packaging bag, or the side where the outer layer of the substrate is formed). The inner side of the packaging bag refers to the side of the packaging bag's substrate that contacts the sheet housed within the packaging bag (i.e., the side where the sheet is housed within the packaging bag, or the side where the inner layer of the substrate is formed). In the first state sample, the composition is such that the density is 0.09 g / cm³. 3 Above and 0.50 g / cm 3 In the following sheet laminate, the first static friction coefficient on the inner surface of the substrate is 0.25 or higher and 0.5 or lower, the second static friction coefficient on the outer surface of the substrate is 0.3 or higher and 0.65 or lower, and the ratio of the first static friction coefficient to the second static friction coefficient is 0.5 or higher and 0.9 or lower. This generates a certain amount of friction on the inner surface of the substrate constituting the packaging bag, and generates a greater friction force on the outer surface of the substrate than the friction force generated on the inner surface of the substrate. Therefore, the frictional force generated on the inner surface of the substrate is relatively smaller on the inner surface and relatively larger on the outer surface, taking the same sheet laminate as a reference. In this configuration, the fingers of a person touching the substrate (hereinafter referred to as fingers) are less likely to slide on the substrate, while the substrate is more likely to slide on the sheet laminate (sheet). Therefore, when the perforations are set in a paper packaging bag, the perforations are easy to open, and even the paper packaging bag can be easily opened. Regarding the second embodiment of the present invention, a packaging bag as described in the first embodiment is provided, wherein the aforementioned substrate comprises: a base layer comprising a paper component; and an inner layer deposited on one side of the aforementioned base layer and disposed on the inner side of the aforementioned packaging bag; the aforementioned inner layer comprises a thermoplastic resin; and the aforementioned thermoplastic resin contains a slip agent. In this specification, a slip agent is an additive that reduces the coefficient of friction. In the second embodiment, the substrate of the packaging bag includes: a base layer comprising paper components; and an inner layer laminated on one side of the base layer and disposed on the inside of the packaging bag; the inner layer contains a thermoplastic resin containing a slip agent, thereby reducing the static friction coefficient between the inner surface of the substrate and the sheet laminate. This facilitates sliding of the inner surface of the substrate against the sheet, making it easier to open even in paper packaging bags where perforations are provided, thus allowing for easy opening of the packaging bag. Regarding the third embodiment of the present invention, a packaging bag as described in the first or second embodiment is provided, wherein the aforementioned substrate comprises: a base layer comprising a paper component; and an outer layer deposited on the other side of the aforementioned base layer and disposed on the outside of the aforementioned packaging bag; the aforementioned outer layer contains an anti-slip agent. In this specification, the anti-slip agent is an additive that increases the coefficient of friction. In the third embodiment, the substrate of the packaging bag includes: a base layer comprising paper; and an outer layer deposited on the other side of the base layer and disposed on the outside of the packaging bag; the outer layer contains an anti-slip agent, thereby increasing the friction between the outer layer of the substrate and the fingers touching the outer layer of the substrate. This makes it less likely for fingers touching the substrate to slip, thus making it easier to open even paper packaging bags when the perforations are provided. Regarding the fourth aspect of the present invention, a packaging bag as described in any of the first to third aspects is provided, wherein the aforementioned first static friction coefficient and the aforementioned second static friction coefficient are static friction coefficients between the CD direction of the aforementioned substrate and the MD direction of the aforementioned sheet. In the fourth state, the coefficient of static friction between the CD direction on the inner surface of the substrate and the MD direction of the sheet is set as the first coefficient of static friction, so that the CD direction on the inner surface of the substrate can easily slide relative to the MD direction of the sheet. Furthermore, the coefficient of static friction between the CD direction on the outer surface of the substrate and the MD direction of the sheet is set as the second coefficient of static friction, so that the CD direction on the outer surface of the substrate is less likely to slide relative to a finger touching the substrate. Therefore, when the sheet is housed in a packaging bag with its MD direction aligned with the CD direction of the substrate, and the perforations are formed in the MD direction of the substrate, if the perforated surface of the packaging bag is pressed with both thumbs and moved away in the CD direction of the substrate, the perforations will open. At this point, the perforations can be easily opened with only a small amount of force, thus further facilitating the opening of the packaging bag. Regarding the fifth embodiment of the present invention, a packaging bag as described in any of the first to fourth embodiments is provided, wherein an opening slit line is formed on the top surface of the aforementioned packaging bag along the MD direction of the aforementioned substrate. In this specification, the opening slit line refers to a slit line (e.g., a hole) in which slit portions and connecting portions (the portion between two slit portions that is not formed with slit portions) are alternately arranged, and if the connecting portion breaks, the slit portions on both sides of it become continuous cuts. In the fifth state, an opening slit line is formed on the top surface of the packaging bag along the MD direction of the substrate. By simply pressing the top surface of the packaging bag with both thumbs and moving each thumb away in the CD direction of the substrate, the opening slit line is broken, thus making it easy to open the packaging bag. Furthermore, the broken opening slit line can be configured as an opening for the sheet formed on the top surface of the packaging bag. Regarding the sixth aspect of the present invention, a sheet packaging body is provided, comprising: a packaging bag as described in any of the first to fifth aspects; and a sheet material contained within the aforementioned packaging bag. In the sixth aspect, the sheet packaging body configured to contain the sheet material within the aforementioned packaging bag achieves the same effect as the aforementioned packaging bag. That is, according to the sixth aspect, a sheet packaging body can be provided that allows the paper packaging bag to be easily opened even when the packaging bag constituting the sheet packaging body is made of paper. This application asserts priority based on Japanese Patent Application No. 2022-056679, filed on March 30, 2022, the entire contents of which are incorporated herein by reference. 100: Sheet Packaging Body 10: Packaging Bag BS: Substrate IS: Inner Surface OS: Outer Surface 10A: Base Layer (Paper Layer) 10B: Inner Layer (Resin Layer) 10C: Outer Layer (Printing Layer) 11: Top Surface 12: Bottom Surface 13, 14: Side Surfaces 15, 16: Short Side Surfaces 20: Sheet Laminate S: Sheet 30: Opening Cutting Line M: Eyelet OP: Removal Port (Opening) 40, 50: Sealing Part (End Sealing) 60: Sealing Part (Bottom Sealing) C: Cutting Part T: Connecting Part L1, L2: Length W1, W2: Width H1, H2: Height Figure 1 is a diagram showing a sheet package containing sheet material inside a packaging bag. Figure 2 is a diagram showing the sheet material contained in the packaging bag. Figure 3 is a diagram of the sheet package of Figure 1 viewed from the top side. Figure 4 is a diagram of the sheet package of Figure 1 viewed from the bottom side. Figure 5 is a diagram of the sheet package of Figure 1 viewed from the front side. Figure 6 is a diagram of the sheet package of Figure 1 viewed from the back side. Figure 7 is a diagram of the sheet package of Figure 1 viewed from the left side. Figure 8 is a diagram of the sheet package of Figure 1 viewed from the right side. Figure 9 is a diagram showing an example of a cross-section of the substrate of the packaging bag. Figure 10 is a diagram showing the sheet package in the opened state of the packaging bag. Figure 11 is a diagram showing the sheet package in use. Domestic storage information (please note in order of storage institution, date, and number): None Overseas storage information (please note in the order of storage country, institution, date, and number): None 100: Sheet packaging 10: Packaging bags BS: Substrate 11: Top surface 12: Bottom surface 13, 14: Side view 15, 16: Short side face 20: Sheet laminate 30: Cutting lines for Kaifeng M: Hole 40, 50: Sealing section (end seal) C: Cutting section T: Connecting part H1: Height

Claims

1. A packaging bag that contains a sheet laminate made of a plurality of sheets, wherein the density of the sheet laminate is 0.09 g / cm³ or more and 0.50 g / cm³ or less; the packaging bag is made of a substrate containing paper components, wherein a first static friction coefficient of the inner surface of the substrate disposed on the inner side of the packaging bag is 0.25 or more and 0.5 or less; a second static friction coefficient of the outer surface of the substrate disposed on the outer side of the packaging bag is 0.3 or more and 0.65 or less; and the ratio of the first static friction coefficient to the second static friction coefficient is 0.6 or more and 0.87 or less.

2. The packaging bag as described in claim 1, wherein, The aforementioned substrate comprises: a base layer comprising the aforementioned paper component; and an inner layer deposited on one side of the aforementioned base layer and disposed on the inner side of the aforementioned packaging bag; the aforementioned inner layer comprising a thermoplastic resin; and the aforementioned thermoplastic resin containing a slip agent.

3. The packaging bag as described in claim 1 or 2, wherein, The aforementioned substrate comprises: a base layer containing the aforementioned paper component; and an outer layer laminated on the other side of the aforementioned base layer and disposed on the outside of the aforementioned packaging bag; the aforementioned outer layer contains an anti-slip agent.

4. The packaging bag as described in claim 1 or 2, wherein, The aforementioned first static friction coefficient and the aforementioned second static friction coefficient are the static friction coefficients between the CD direction of the aforementioned substrate and the MD direction of the aforementioned sheet.

5. The packaging bag as described in claim 1 or 2, wherein, On the top surface of the aforementioned packaging bag, there is an opening cut line along the MD direction of the aforementioned substrate.

6. A sheet packaging body comprising: a packaging bag as described in any one of claims 1 to 5; and a sheet contained in the aforementioned packaging bag.

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