AU2021249695B2 - Corrugated fiberboard material - Google Patents

Abstract

A corrugated fiberboard material (1) using a corrugated fiberboard in which a linerboard is adhered to a corrugating medium, wherein a measurement piece that has been cut out of the linerboard has a dynamic viscoelasticity within a prescribed range, as measured in a pulling/shearing mode with a temperature condition of 25 [°C] and a vibration condition of 100 [Hz] frequency. The dynamic viscoelasticity is defined by the value of the elastic modulus E' and the value of tanδ, which is the ratio of the loss modulus E'' to the elastic modulus E'. The prescribed range for the elastic modulus E' is 1.00×10

Description

DESCRIPTION CORRUGATED FIBERBOARD MATERIAL TECHNICAL FIELD

[0001] The present invention relates to a corrugated cardboard material.

BACKGROUND ART

[0 [0002] A corrugated cardboard material folded zigzag (also called "fan-folded") is known as a material for making boxes. The corrugated cardboard material is provided with creases between continuous rectangular sheets, and the sheets are alternately folded back at the

[5 creases. In such a fan-folded corrugated cardboard material, the continuous sheets are vertically stacked and folded into a packaging style of a rectangular parallelepiped.

[0003] A folding apparatus for producing aforementioned corrugated cardboard materials folded zigzag includes a folding part for alternately folding back continuous !o sheets at creases, and a stacking part for stacking the folded sheets (see Patent Literature 1 below, for example). In order to assure the stability and the regularity of the packaging style of produced corrugated cardboard materials, it is desirable that sheets which are continuous via creases are folded by the stacking part so as to come in contact with !s each other without spaces therebetween.

[0004] The corrugated cardboard material described above is used as a packaging material in a box-making system (also called "automated packaging system", "three sides variable system", "three sides automated packaging", "on demand packaging", etc.) that manufactures boxes having optimum sizes according to the sizes of objects to be packaged. The box-making system performs various steps illustrated below (see Patent Literature 2 below). - Feeding step: A step that feeds the fan-folded corrugated cardboard material - Cutting step: A step that cuts the flat corrugated cardboard material fed in the feeding step - Folding step: A step that assembles boxes from the corrugated cardboard material cut in the cutting step - Printing step: A step that performs printing on the flat or assembled corrugated cardboard material - Packing step: A step that packs contents in the assembled boxes

PRIOR ART DOCUMENTS PATENT LITERATURE

[0005] Patent Literature 1: Japanese Laid-Open Patent Application (Translation of PCT Application) No. 2015-509473 Patent Literature 2: Japanese Laid-Open Patent Publication (Translation of PCT Application) No. 2013-513869 Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.

[0

SUMMARY OF INVENTION PROBLEM TO BE SOLVED BY INVENTION

[0006]

[5 However, there may be a space between sheets which are continuous via a crease ("the creases open") depending on the properties of a corrugated cardboard material used, which may lead to insufficiency of the property of keeping the folded state of the sheets at the crease (folding retention ability). This may result in insufficiency of the stability and the regularity of the packaging style. Additionally, there !o may be cases where a damage (crease crack) is likely to occur at the portions of the creases when sheets are folded back at the creases depending on the properties of a corrugated cardboard material used. Further, when a corrugated cardboard material provided with creases such as a corrugated cardboard material folded zigzag is used as the material in a box-making system, there is a possibility that rips (damage) are likely !s to occur in produced boxes depending on the properties of sheets used in the corrugated cardboard material. Further, a corrugated cardboard material provided with creases such as a corrugated cardboard material folded zigzag, there may be a possibility that rips (crease cracks) are likely to occur at the portions of the creases depending on the properties of sheets used in the corrugated cardboard material. The present disclosure has been conceived in view of the above problems, and one object thereof is to assure the folding retention ability as well as suppressing crease cracks at the same time. Additionally, one object thereof is to suppress rips (damage) of a box manufactured using a corrugated cardboard material. Further, one object thereof is to suppress crease cracks at the portions of creases. However, the objects of the present disclosure are not limited to these, and may also be regarded as to yield actions and effects that are derived from each configuration described in the following "DESCRIPTION OF EMBODIMENTS" and that cannot be obtained by the conventional techniques.

MEANS TO SOLVE PROBLEM

[0007]

(1) A corrugated cardboard material disclosed herein is a corrugated cardboard material including a cardboard including a liner attached to a medium. In this corrugated cardboard material, a dynamic viscoelasticity measured on a measurement piece cut out from the liner in a tensile shear mode of a vibration condition of a frequency of 100

[Hz] under a temperature condition of 25 [°C] is within a predetermined range, and the dynamic viscoelasticity is defined by a value of an elastic modulus E' and a value of tan6 which is a ratio of a loss elastic modulus E" to the elastic modulus E'. The predetermined range includes: the elastic modulus E' of 1.00 x 109 [Mpa] or more and 8.00 x 109 [Mpa] or less, and the tan6 of 2.50 x 10-2 or more and 1.50 x 10-1 or less.

[0 [0008] (2) Further, a corrugated cardboard material disclosed herein is a corrugated cardboard material including a cardboard including a liner attached to a medium. In the present corrugated cardboard material, an amount of a sizing agent added to the liner is 0.2 [parts by mass] or more and 4.0 [parts by mass] or less, an amount of a paper

[5 strength agent added to the liner is 0.1 [parts by mass] or more and 4.0 [parts by mass] or less, a length mean fiber length of pulp fibers constituting the liner is 0.90 [mm] or more and 1.55 [mm] or less, an amount of fine fibers having a fiber length of 0.0 [mm] or more and 0.2 [mm] or less included in the pulp fibers constituting the liner is 23 [%] or more and 48 [%] or less. !o [0009] (3) Further, a corrugated cardboard material disclosed herein is a corrugated cardboard material including a cardboard including a liner attached to a medium. In the present corrugated cardboard material, a density of the liner is 0.60 [g/cm 3] or more and 0.85 [g/cm3] or less, a length mean fiber length of pulp fibers constituting the liner is !s 0.98 [mm] or more and 1.55 [mm] or less, an amount of fine fibers having a fiber length of 0.0 [mm] or more and 0.2 [mm] or less included in the pulp fibers constituting the liner is 15 [%] or more and 38 [%] or less.

EFFECTS OF INVENTION

[0010] (1) According to the present disclosure, it is possible to assure the folding retention ability and suppress crease cracks at the same time. (2) According to the present disclosure, it is possible to suppress damage of a box manufactured using a corrugated cardboard material. (3) According to the present disclosure, it is possible to suppress crease cracks at the portions of creases.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]

[FIG. 1] FIG. 1 is a perspective view illustrating a corrugated cardboard material folded zigzag.

[FIG. 2] FIG. 2 is an illustrative view for describing a folding mechanism.

[FIG. 3A] FIG. 3A is an illustrative view illustrating the packaging style of a corrugated cardboard material folded zigzag, which is a good packaging style.

[FIG. 3B] FIG. 3B is an illustrative view illustrating the packaging style of a corrugated cardboard material folded zigzag, which is a bad packaging style.

DESCRIPTION OF EMBODIMENTS

[0012] Hereinafter, a corrugated cardboard material as an embodiment will be described.

[0 The corrugated cardboard material primarily exemplified in the present embodiment is a material for making boxes and is folded zigzag in which rectangular sheets in a continuous corrugated cardboard are folded. As the corrugated cardboard material, a double-faced corrugated cardboard having liners on both sides of a medium is used.

[5 [0013] The above double-faced corrugated cardboard may be, as well as a corrugated cardboard with a single wall constituted by three base papers (materials) corresponding to one medium and two liners, a corrugated cardboard with a multi-wall constituted by five or more base papers corresponding to three or more mediums and two liners, such !o as a so-called "double wall corrugated cardboard" or "triple wall corrugated cardboard". In the present embodiment, a corrugated cardboard material formed of a double-faced corrugated cardboard with a single wall is primarily exemplified.

[0014] The corrugated cardboard material is formed into boxes to become corrugated !s cardboard boxes. Specifically, the corrugated cardboard material used as a material for making boxes in a box-making system is formed into the corrugated cardboard boxes through various steps such as a feeding step that feeds sheets in sequence, a cutting step that cuts the fed sheets into a development pattern of a box, a folding step that folds the sheets into a box shape. The box-making system for assembling corrugated cardboard boxes is not particularly limited, but may be, for example, a fully automated system such as "CartonWrap 1000 manufactured by CMC machinery", "CVP-500 manufactured by Neopost", and "TXP-600 manufactured by Os Machinery", or a semi automated system such as "EM7 manufactured by Packsize", and "Compack manufactured by Panotec".

[0015] The present embodiment illustrates the correspondence of the following directions I and II as shown in Table 1 below, and assumes that the corrugated cardboard material is placed on a horizontal plane. - Direction I: A direction in the corrugated cardboard placed on the horizontal plane - Direction II: A direction in a semi-finished product in the middle of manufacturing the corrugated cardboard material

[0016]

[Table 1] Direction I Direction II Longitudinal Direction CD Direction Lateral Direction MD Direction Height Direction TD Direction

[0017] A longitudinal direction (first direction, indicated by "CD" in the drawings) and a lateral direction (second direction, indicated by "MD" in the drawings) are each horizontal and each extend along a plane that contains sheets (creases). These longitudinal and lateral directions are orthogonal to each other. A height direction (third direction, indicated by "TD" in the drawings) is vertical and is orthogonal to both the longitudinal direction and the lateral direction. This height direction corresponds to the direction in which the sheets are stacked.

[0 [0018] The MD (Machine Direction) direction is also referred to as a "flow direction", and is a direction in which a manufacturing process of the corrugated cardboard material progresses from an upstream side to a downstream side. The CD (Cross Direction) direction is orthogonal to the MD direction in a plane that extends along the

[5 MD direction. The TD (Transverse Direction) direction is orthogonal to both the MD direction and the CD direction. Unless otherwise specified, the expression "numerical value X to numerical value Y" in the present embodiment means a range of the numerical value X or more and the numerical value Y or less. !o [0019]

[I. One Embodiment] In one embodiment below, the configuration of the corrugated cardboard material will be described in items [1] and [2]. Item [1] describes a structure (hereinafter referred to as "folded structure") in which the corrugated cardboard material is folded. Item [2] describes parameters related to properties of sheets (corrugatedcardboard sheets) used for the corrugated cardboard material. Finally, the actions and effects derived from the configurations of items [1] and

[2] will be described in item [3].

[0020]

[1. Folded Structure] As illustrated in FIG. 1, a corrugated cardboard material 1 is used for making boxes and is shaped into a rectangular parallelepiped. In the corrugated cardboard material 1, continuous rectangular sheets 2 (only some of which are denoted by reference signs in FIG. 1) are folded back at creases F (only some of which are denoted by reference signs in FIG. 1) and the folded sheets 2 are stacked in the height direction.

In the corrugated cardboard material 1 folded by such a manner, the multiple creases F each extend straightly along the longitudinal direction on a pair of side faces that extend along both the longitudinal direction and the height direction.

[0021] By focusing on three consecutive sheets 2 (indicated by two-dot chain lines in FIG. 1), the folded structure of the corrugated cardboard material 1 will now be described. - First sheet 21: A sheet 2 continuous with one side of a second sheet 22 - Second sheet 22: A sheet 2 continuous with both the first sheet 21 and a third sheet t0 23 - Third sheet 23: A sheet 2 continuous with the other side of the second sheet 22

[0022] A first crease F1 is provided between the first sheet 21 and the second sheet 22, which means that the sheets 21 and 22 are continuous via the first crease Fl. A second

[5 crease F2 is provided between the second sheet 22 and the third sheet 23, which means that the sheets 22 and 23 are continuous via the second crease F2. The first crease F1 is a crease F at which the second sheet 22 is folded back toward one side (right in FIG. 1) in the lateral direction from the first sheet 21, and is arranged on the other side (left in FIG. 1) in the lateral direction of the corrugated !o cardboard material 1. The second crease F2 is a crease F at which the third sheet 23 is folded back toward the other side (left in FIG. 1) in the lateral direction from the second sheet 22, and is arranged on the one side (right in FIG. 1) in the lateral direction of the corrugated cardboard material 1.

[0023] !s In the first sheet 21, flute shapes 10 (corrugating shape) of the corrugated cardboard are exposed on first edges E1 (only one of which on the front side is denoted by a reference sign in FIG. 1) that extend in the lateral direction (the direction intersecting the creases F). Similarly, in the second sheet 22, the flute shapes 10 of the corrugated cardboard are exposed on the second edges E2 (only one of which on the front side is denoted by a reference sign in FIG. 1) that extend in the lateral direction (the direction intersecting the creases F). In a sheet pair 20 consisting of the first sheet 21 and the second sheet 22, the first edges E1 and the second edges E2are arranged adjacent to each other in the height direction.

[0024] According to the corrugated cardboard material 1 having the folded structure described above, even a material that is difficult to be wound in a roll can be folded into a rectangular parallelepiped. That is, a compact packaging style can be achieved in the sheets 2 of the corrugated cardboard having a strength higher than that of the material windable in a roll. The corrugated cardboard material 1, which is constituted by the folded sheets 2 having an ensured strength as described above, is suitable for a packaging material in a box-making system that manufacture boxes requiring a strength.

[0025] The creases F are provided along the flute shapes 10 of the corrugated cardboard. In other words, the corrugated cardboard material 1 is manufactured so as to have the flute shapes 10 perpendicular to the MD direction. The corrugated cardboard material 1 is preferably wrapped with (packed by) a film for packaging in order to prevent stains or collapse.

[0026]

[2. Parameters] Hereinafter, parameters of the corrugated cardboard material 1 will now be

[0 described. First, basic parameters such as the size and the number of boards of the corrugated cardboard material 1 will be described. Next, parameters relating to the sheets 2 of the corrugated cardboard material 1 will be described in detail.

[0027]

[5 [2-1. Basic Parameters] The size of the corrugated cardboard material 1 is defined by the following dimensions Li to L3. - Longitudinal dimension L1: A dimension (first dimension) in the longitudinal direction - Lateral dimension L2: A dimension (second dimension) in the lateral direction !o - Height dimension L3: A dimension (third dimension) in the height direction The smaller dimensions Lito L3 may cause greater restrictions on the size and the shape of the boxes to be manufactured, and the larger dimensions Li to L3 may cause degradation in workability in transportation and/or delivery. From these viewpoints, the dimensions Lito L3 are preferably within ranges described in Table 2 !s below.

[0028]

[Table 2] Preferable Range More Preferable Range Longitudinal Dimension Li 500 to 2500 [mm] 700 to 2000 [mm] Lateral Dimension L2 800 to 2500 [mm] 1000 to 2200 [mm] Height Dimension L3 700 to 2000 [mm] 1200 to 2000 [mm]

[0029] When the number of the creases F in the corrugated cardboard material 1 is N, the number of the sheets 2 is N+1. In the present disclosure, N+1 [boards] of the sheets 2 are stacked in the corrugated cardboard material 1. For example, the number of boards in the corrugated cardboard material 1 may be, for example, various numbers from 10 to 1000. Regarding the corrugated cardboard material serving as a target for which parameters relating to folding is measured as to be described later, the parameters are preferably measured in every single board if the measurement target has less than a predetermined number (for example, 100) of boards. On the other hand, if the measurement target has a predetermined number (for example, 100) or more of boards, the parameters may be measured in a part (for example, a divided part or a fixed area).

[0030] The basis weight can be arbitrarily set for the sheets 2 used in the corrugated cardboard material 1. The range of the basis weight to be adopted for the sheets 2 may be a range of 50 to 1500 [g/m 2], preferably a range of 100 to 1000 [g/m 2 ], and more preferably a range of 200 to 800 [g/m 2], and further preferably a range of 200 to 600 2

[g/m ]. The weight of the corrugated cardboard material 1 is calculated by multiplying

[0 the above basis weight by the longitudinal dimension L1, the lateral dimension L2, and the number N+1 of the sheet 2, taking the take up factor of each medium into considerations.

[0031]

[2-2. Parameters Relating to Properties]

[5 <Feature A> The corrugated cardboard material 1 of the present embodiment includes a Feature A relating to the properties on the basis of the viewpoint of achieving a good packing style of the corrugated cardboard material 1. Specifically, the corrugated cardboard material 1 includes the predetermined Feature A relating to properties on the !o basis of the following viewpoints I and II. The "packaging style of corrugated cardboard material 1" is the appearance of the corrugated cardboard material 1 folded zigzag and folded into a rectangular parallelepiped shape. - Viewpoint I: To assure the folding retention ability at creases F - Viewpoint II: To prevent crease cracks at creases F !s The above Viewpoints I and II are established for solving the following Problems I and II. - Problem I: Folding opens at a crease F - Problem II: A crease crack occurs at a crease F

[0032] The "folding retention ability" in the above Viewpoint I referred to is the property of retaining the state where the sheets 2 remain folded at the creases F. The "folding opens at crease F" referred to in Problem I is that when sheets 2 are folded back at creases F, the folded-back state is not retained, so that there is space between sheets 2 that are continuous via the crease F. Problem I occurs when the folding retention ability is insufficient. Problem I can also be considered to be a problem in which the packaging style of the corrugated cardboard material 1 is disturbed by opening of folding at a crease F. A "crease crack" in the above Viewpoint II and Problem II is a crack (damage, rip) occurred in a liner located outside a crease F when sheets 2 are folded back at the crease F.

[0033]

When an attempt is made to assure the folding retention ability on the basis of Viewpoint I, Problem IItends to occur; when an attempt is made to suppress crease cracks at creases F on the basis of ViewpointII, Problem I tends to occur. Accordingly, achieving both Viewpoint I and Viewpoint II is difficult. Hereinafter, as a prerequisite of the above Viewpoints I and II, the configuration of a folding apparatus for manufacturing a corrugated cardboard material 1 folded zigzag, and the packaging style of a manufactured corrugated cardboard material 1 will be described in Sub-items [i] and [ii]. Thereafter, a predetermined feature on the basis of Viewpoints I and II in Sub-item [iii] will be described.

[0 [0034]

[i. Folding Apparatus] A folding apparatus 50 illustrated in FIG. 2 is an apparatus for folding corrugated cardboards which extend continuously in a band shape into a fan-folded shape.

[5 Although there is no particular limitation on the folding apparatus 50, the following folding apparatus can be used, for example. - Folding apparatus: manufactured by BHS Corrugated Machinery Product No. "AS-F",

[0035] !o The folding apparatus 50 includes a conveying part 50A, a folding part 50B, and a stacking part 50C. The conveying part 50A forms a conveying path for conveying a band-shaped corrugated cardboard web 1W produced by an upstream cardboard production apparatus (corrugator), which is not illustrated, to the folding part 50B (see the two-dot !s chain lines in FIG. 2).

[0036] The corrugated cardboard web 1W produced by the corrugator which is not illustrated is provided with a plurality of creases F spaced at regular intervals in the lateral direction. Sheets 2 (see FIG. 1) are continuous on the upstream and downstream sides of each crease F. The plurality of creases F include creases at which sheets on the upstream side are folded back with respect to sheets on the downstream side toward one of the lateral directions (toward the right in FIG. 2) (creases corresponding to "first creases F1" in FIG. 1), and creases at which sheets on the upstream side are folded back with respect to sheets on the downstream side toward the other of the lateral directions (toward the left in FIG. 2) (creases corresponding to "second creases F2" in FIG. 1). These first creases F1 and the second creases F2 extend alternately along the conveying direction.

[0037] The surface facing upward in the conveyance part 50A is referred to as the front surface of the corrugated cardboard web 1W, and the surface facing downward is referred to as the back surface of the corrugated cardboard web 1W. The first creases F1 are formed as grooves recessed in the front surface of the corrugated cardboard web 1W and the second creases F2 are formed as grooves recessed in the back surface of the corrugated cardboard web 1W, such that folding is assured in each of the above directions.

[0038] The folding part 50B is provided between the conveyance part 50A and the stacking part 50C, and is a part that alternately folds back the corrugated cardboard web 1W conveyed by the conveyance part 50A at the creases F and sends it to the stacking part 50C. In the folding part 50B, the corrugated cardboard web 1W conveyed from the

[0 conveying part 50A falls downward while being pushed out in the conveying direction. At this time, sheets on the upstream side are folded back with respect to sheets on the downstream side toward one of the lateral directions (toward the right in FIG. 2) at the first creases F1, and sheets on the upstream side are folded back with respect to sheets on the downstream side toward the other of the lateral directions (toward the left in FIG.

[5 2) at the second creases F2.

[0039] The folding part 50B may be provided with an auxiliary mechanism (not illustrated) that assists in folding-back of the corrugated cardboard web 1W. The auxiliary mechanism is a mechanism for assisting the sheets forming the corrugated !o cardboard web 1W is reliably folded back at the first creases F1 and the second creases F2 alternately. Although there is no particular limitation on the specific structure of the auxiliary mechanism, a rotation mechanism provided with a rod supporting the second creases F2 (see Patent Literature 1 described above) can be used, for example.

[0040] !s The stacking part 50C is a part that stacks sheets that are alternately folded back at the folding part 50B. The stacking part 50C is disposed below the folding part 50B. Hence, in the stacking part 50C, the sheets 2 which are alternately folded back at the creases F1 and F2 (see FIG. 1) are stacked sequentially from the bottom to the top. As a result, the corrugated cardboard material 1 folded zigzag having a packaging style of a rectangular parallelepiped is produced.

[0041]

[ii. Good or Bad Packing Style] In a corrugated cardboard material 1 having a good packaging style, as illustrated in FIG. 3A, after sheets which are continuous via creases F are folded back by 180 [0] at the creases F, the sheets which are continuous via the creases F are folded back so as to come in contact with each other without opened spaces. In cases where creases F remain in a closed state in this manner, there is a possibility of occurrence of Problem IIof crease cracks at the creases F although the packing style of the corrugated cardboard material 1 is good.

[0042] In a corrugated cardboard material 1 having a bad packaging style, as illustrated in FIG. 3B, after sheets which are continuous via creases F are folded back by 180 [0] at the creases F, subsequent sheets are stacked having space S between sheets which are continuous via the crease F. If the crease F does not remain closed in this manner, there is a possibility of Problem I of opening of a fold at a crease F although crease cracks at creases F are less likely to occur. This may lead to a bend of the sheet at the portion of the space S or inclination of the corrugated cardboard material 1 above the space S, and the regularity and the stability of the corrugated cardboard material 1 may be impaired. As a result, the stacked sheets may collapse during sheets are being folded zigzag, which makes manufacturing of a corrugated cardboard material 1 folded zigzag impossible.

[0 [0043]

[iii. Feature] The corrugated cardboard material 1 includes the following Feature 1A as a Feature A corresponding to the above Viewpoints I and II and Problems I and II. - Feature 1A: The dynamic viscoelasticity of the liner constituting the corrugated

[5 cardboard material 1 is within a predetermined range. The "dynamic viscoelasticity" is a parameter defined by three values: elastic modulus E', loss elastic modulus E", and tan6, and is a parameter corresponding to the retentionability of the folded state (resistance to opening of the creases F) and the resistance to crease cracks at the creases F when the corrugated cardboard material 1 !o is bent. When the corrugated cardboard material 1 is bent at the creases F, pulp fibers forming the liner base papers of the corrugated cardboard material 1 are stretched. The "dynamic viscoelasticity" can be regarded as a parameter corresponding to the ability to retain the stretched state of the pulp fibers when the corrugated cardboard material 1 is bent at the creases F. !s [0044] The elastic modulus E' represents the degree of elasticity, and corresponds to the repulsive force serving to return to the original shape (i.e., serving to open the creases F) when the corrugated cardboard material 1 is bent. The loss elastic modulus E" represents a high degree of viscosity. Tan6 is the ratio of the loss elastic modulus E" to the elastic modulus E' based on the following Equation 1. Tan6 with a value of "1" or less indicates possession of the physical property in the elastic region (the region returning to the original shape), and tan6 otherwise indicates possession of the physical property in the viscosity region (the region where returning to the original shape is difficult). Tan 6 = E"/E' . . Equation 1 The greater the value of tan6 is, the smaller the above-mentioned repulsive force becomes; the smaller the value of tan6 is, the greater the above-mentioned repulsive force becomes.

[0045] The present inventors have attained the finding that, when the elastic modulus E' and tan 6 among the dynamic viscoelasticity of a liner constituting a corrugated cardboard material 1 are within predetermined ranges, the above Problems I and II tend to be suppressed. Conversely speaking, the present inventors found that corrugated cardboard material having a liner with the dynamic viscoelasticity outside the predetermined range tend to have Problems I and II. This means that Feature 1A is applied to the corrugated cardboard material 1 on the basis of the above Viewpoints I and II.

[0046] If the elastic modulus E' is more than a predetermined range and tan6 is less than a predetermined range among the dynamic viscoelasticity, the pulp fibers forming the liner base paper would not remain stretched and the repulsive force serving to open

[0 the creases F would increase when the corrugated cardboard material 1 is bent at the creases F, which is presumed to cause Problem I. If the elastic modulus E' is less than the predetermined range and tan6 is more than the predetermined range among the dynamic viscoelasticity, when the corrugated cardboard material 1 is bent at the creases F, an external force due to bending would be applied to the creases F while the pulp fibers forming the liner base paper are stretched, which is presumed to cause Problem II.

[0047] The elastic modulus E' is 1.00 x 109 [Mpa] or more and 8.00 x 109 [Mpa] or less and tan6 is 2.50 x 10-2 or more and 1.50 x 10-1 or less. When the values of elastic !o modulus E' and tan6 are within these ranges, it is possible to obtain a corrugated cardboard material suitable as a box-making material. In view of suitability for producing a corrugated cardboard material folded zigzag, it is preferable that the elastic modulus E' is 1.50 x 109 [Mpa] or more and 7.00 x 109

[Mpa] or less, and tan6 is 3.00 x 10-2 or more and 1.00 x 10-1 or less. !s In view of suitability for use in an automated packaging system, the elastic modulus E' is more preferably 2.00 x 109 [Mpa] or more and 6.00 x 109 [Mpa] or less, and tan6 is more preferably 3.50 x 10-2 or more and 9.70 x 10-2 or less.

[0048] Further, on the basis of Viewpoint I, it is preferable that the elastic modulus E' is 3.00 x 109 [Mpa] or less and tan6 is 7.00 x 10-2 or more, and it is more preferable that the elastic modulus E' is 2.50 x 109 [Mpa] or less and tan6 is 8.00 x 10-2 or more. On the basis of Viewpoint II, it is preferable that the elastic modulus E' is 4.00 x 109 [Mpa] or more and tan6 is 4.00 x 10-2 or less, and it is more preferable that the elastic modulus E' is 4.50 x 109 [Mpa] or more and tan6 is 3.80 x 10-2 or less.

[0049] <Feature B> Further, on the basis of producing a box that is resistant to rips when used as a material for making boxes, the corrugated cardboard material 1 of the present embodiment includes Feature B relating to the properties. Specifically, on the basis of the following viewpoint II, the corrugated cardboard material 1 includes the predetermined Feature B relating to properties. - Viewpoint III: To suppress rips (damage) in assembled boxes

The above Viewpoint III is a viewpoint for solving the following problem III. - Problem III: The assembled boxes have a risk of being easily ripped

[0050] In cases where the corrugated cardboard material 1 folded zigzag is used for the box making material of a box making system (automatic packaging system), creases F may be included in the bottom surface or side surfaces of the assembled box. In boxes assembled using the corrugated cardboard material 1 folded zigzag, there is a tendency that ripping is likely to occur starting from the portions of the creases F. Accordingly, the above Problem III can be regarded that boxes assembled using the

[0 corrugated cardboard material 1 folded zigzag have a risk of being easily ripped. Ripping starting from the portions of the creases F described above tends to occur more easily under a humid condition. Accordingly, the above Problem III can also be considered to be a problem in that the boxes assembled using the corrugated cardboard material 1 folded zigzag have a risk of being easily ripped under a humid

[5 condition.

[0051] The corrugated cardboard material 1 includes the following Features B1 to B4 as Feature B corresponding to the above Viewpoint III and Problem III. - Feature B1: The amount of a sizing agent added is within a predetermined range !o - Feature B2: The amount of a paper strength agent added is within a predetermined range - Feature B3: The length mean fiber length of the fiber lengths is within a predetermined length range - Feature B4: The amount of fine fibers is within a predetermined range !s [0052] The "sizing agent" is a chemical agent added to a liner forming the corrugated cardboard material 1 in order to impart surface characteristics such as sizing property (a function of preventing penetration of water and ink bleeding) and printability to the liner. The amount of the sizing agent added [parts by mass] is the ratio of the added amount of the sizing agent [parts by mass] contained in every total 100 [parts by mass] of the total pulp constituting the liner. The "paper strength agent" is a chemical agent added to a liner forming the corrugated cardboard material 1 in order to improve the surface strength of the liner and prevent generation of paper dusts during printing. The amount of the paper strength agent added [parts by mass] is the ratio of the added amount of the paper strength agent [parts by mass] contained in the every total 100 [parts by mass] of the total pulp constituting the liner.

[0053] The "length mean fiber length" is the average of the lengths of pulp fibers constituting a liner (fiber lengths). This length mean fiber length is the average of the lengths of pulp fibers including fine fibers to be described below.

The "amount of fine fibers" is the proportion [%] of the amount of contained fine fibers relative to the total pulp fibers (taken to be 100 [%]) constituting a liner. Here, the fine fibers are fine fibers having fiber lengths of 0.0 [mm] or more and 0.2 [mm] or less.

[0054] The present inventors have attained the finding that, if a liner forming the corrugated cardboard material 1 has the above Features B1 to B4, the above Problem III tends to be suppressed. Conversely speaking, present inventors have found that a corrugated cardboard material using a liner that does not include at least one of the above Features B1 to B4 tends to have Problem III.

[0 In other words, the corrugated cardboard material 1 has the above Features B1 to B4 on the basis of the above Viewpoint III.

[0055] If the amount of the sizing agent added is less than the predetermined range or if the amount of the paper strength agent added is less than the predetermined range,

[5 the strength of the liner would become insufficient when the length mean fiber length of the fiber lengths is less than the predetermined length range, which is presumed to cause Problem III. If the amount of the sizing agent added is more than the predetermined range, the sizing agent would inhibit hydrogen bonds between the pulp fibers constituting the !o liner, which is presumed to cause Problem III. Although the strength of a liner tends to increase as the amount of the paper strength agent added increases, the paper strength agent would be aggregated and the strength would be lowered when the amount of the paper strength agent added is more than the predetermined range, which is presumed to cause Problem III. !s [0056] Although the strength of a liner tends to increase as the length mean fiber length increases, spaces between the pulp fibers would increase when the length mean fiber length is more than the predetermined length range, which is presumed to cause Problem III. In particular, water is easily absorbed into pulp fibers through spaces under a humid condition, which is presumed to cause Problem III to be more likely to occur.

[0057] If the amount of fine fibers is less than predetermined range, the proportion of pulp fibers having greater fiber lengths (long fibers) would increase and spaces between long fibers would increase, which is presumed to cause Problem III. In particular, water is more likely to be absorbed through spaces between long fibers under a humid condition, which makes Problem III to be more likely to occur. If the amount of fine fibers is more than the predetermined range, the proportion of long fibers would decrease and the pulp fibers would be less tangled, which is presumed to cause Problem III.

[0058]

The amount of the sizing agent added is 0.2 [parts by mass] or more and 4.0

[parts by mass] or less, preferably 0.5 [parts by mass] or more and 3.0 [parts by mass] or less, and more preferably 0.8 [parts by mass] or more and 2.0 [parts by mass] or less. The amount of the paper strength agent added is 0.1 [parts by mass] or more and 4.0 [parts by mass] or less, preferably 0.5 [parts by mass] or more and 3.5 [parts by mass] or less, and more preferably 1.0 [parts by mass] or more and 3.0 [parts by mass] or less.

[0059] The length mean fiber length is 0.90 [mm] or more and 1.55 [mm] or less,

[0 preferably 1.00 [mm] or more and 1.53 [mm] or less, and more preferably 1.30 [mm] or more and 1.52 [mm] or less. The amount of fine fibers is 23 [%] or more and 48 [%] or less, preferably 30 [%] or more and 47 [%] or less, and more preferably 40 [%] or more and 46 [%] or less.

[0060]

[5 <Feature C> On the basis of the viewpoint of reducing occurrence of rips (crease cracks) at the portions of the creases F, the corrugated cardboard material 1 of the present embodiment includes Feature C relating to properties. Specifically, on the basis of the following viewpoint IV, the corrugated cardboard material 1 includes predetermined !o Feature C relating to properties. - Viewpoint IV: To suppress crease cracks at portions of the creases F The above Viewpoint IV is a viewpoint for solving the following problem IV. - Problem IV: There is a risk of crease cracks at portions of the creases F. The creases F of the corrugated cardboard material 1 folded zigzag are portions !s at which continuous sheets are folded back by 180 [0]. In the corrugated cardboard material 1 folded zigzag, there is a tendency that crease cracks are likely to occur at the portions of the creases F. Accordingly, the above Problem IV can be regarded as a problem in that the corrugated cardboard material 1 folded zigzag is likely to have crease cracks at the portions of the creases F. The corrugated cardboard material 1 includes the following Features C1 to C3 as Feature C corresponding to the above Viewpoint IV and Problem IV. - Feature Cl: The density of a liner is within a predetermined range - Feature C2: The length mean fiber length of the fiber lengths is within a predetermined length range - Feature C3: The amount of fine fibers is within a predetermined range

[0061] The "density" is a parameter representing the weight [g] per volume of 1 [cm 3] Of a liner forming the corrugated cardboard material 1. The "length mean fiber length" is the average of the lengths of pulp fibers constituting a liner (fiber lengths). This length mean fiber length is the average of the lengths of pulp fibers including fine fibers to be described below.

The "amount of fine fibers" is the proportion [%] of the amount of contained fine fibers relative to the total pulp fibers (taken to be 100 [%]) constituting a liner. Here, the fine fibers are fine fibers having fiber lengths of 0.0 [mm] or more and 0.2 [mm] or less.

[0062] The present inventors have attained the finding that, if a liner forming the corrugated cardboard material 1 has the above Features C1 to C3, the above Problem IV tends to be suppressed. Conversely speaking, present inventors have found that a corrugated cardboard material using a liner that does not include at least one of the above Features C1 to C3 tends to have Problem IV.

[0 In other words, the corrugated cardboard material 1 has the above Features C1 to C3 on the basis of the above Viewpoint IV.

[0063] If the density is less than the predetermined range, a lot of spaces would be generated between pulp fibers and the strength of the liner would become insufficient,

[5 which is presumed to cause Problem IV. If the density is more than the predetermined range, there would be no spaces between the pulp fibers and the stress would become difficult to escape when the liner is bent, which is presumed to cause Problem IV. The strength of the liner is reduced as the length mean fiber length is reduced. !o Thus, if the length mean fiber length is less than the predetermined length range, the strength of the liner would become insufficient, which is presumed to cause Problem IV.

[0064] The strength of the liner tends to increase as the length mean fiber length increases. However, if the length mean fiber length is more than the predetermined !s length range, the pulp fibers would be more likely to be unevenly distributed and the strength would be locally compromised at some portions, which is presumed to cause Problem IV. If the amount of fine fibers is less than predetermined range, the proportion of pulp fibers having greater fiber lengths (long fibers) would increase and spaces between long fibers would increase, which is presumed to cause Problem IV. If the amount of fine fibers is more than the predetermined range, the proportion of long fibers would decrease, the pulp fibers would be less tangled, and the strength of the liner would become insufficient, which is presumed to cause Problem IV.

[0065] The density of the liner is 0.60 [g/cm 3 ] or more and 0.85 [g/cm 3 ] or less, preferably 0.65 [g/cm3] or more and 0.84 [g/cm 3 ] or less, and more preferably 0.80

[g/cm3] or more and 0.83 [g/cm 3] or less. The length mean fiber length is 0.98 [mm] or more and 1.55 [mm] or less, preferably 1.00 [mm] or more and 1.53 [mm] or less, and more preferably 1.10 [mm] or more and 1.52 [mm] or less. The amount of fine fibers is 15 [%] or more and 38 [%] or less, preferably 17[%] or more and 37 [%] or less, and more preferably 18 [%] or more and 36 [%] or less.

[0066]

[3. Actions and Effects] (1) Because the corrugated cardboard material 1 of the present embodiment includes the above Feature A, the corrugated cardboard material 1 does not open at the creases F when folded back at the creases F. Further, because crease cracks are less likely to occur at the creases F, it is possible to assure the folding retention ability as well as suppressing crease cracks at the same time. As a result, the regularity and the stability of the packaging style of the corrugated cardboard material 1 folded zigzag are assured, for example.

[0 [0067] (2) Further, because the corrugated cardboard material 1 of the present embodiment includes the above Feature B, the strength of a liner forming the corrugated cardboard material 1 is assured. Accordingly, ripping of a box manufactured using the corrugated cardboard material 1 can be suppressed. In particular, it is

[5 possible to suppress the ripping starting from the portions of the creases F under a humid condition.

[0068] (3) Further, because the corrugated cardboard material 1 of the present embodiment includes the above Feature C, the strength of a liner forming the !o corrugated cardboard material 1 is assured. Accordingly, it is possible to suppress ripping of the corrugated cardboard material 1 at the portions of the creases F (crease cracks). EXAMPLE

[0069] !s [11. Example] Hereinafter, Features A, B, and C of the present invention will be specifically described with reference to Examples and Comparative Examples. However, the present invention should not be limited to the following Examples. The corrugated cardboard materials (hereinafter referred to as "measurement corrugated cardboard materials") serving as targets for measuring parameters in Examples and Comparative Examples are sheets of double-faced corrugated cardboard. The measurement corrugated cardboard material has the following size. - Size: Longitudinal dimension 1300 [mm], Lateral dimension 1150 [mm], Height dimension 1800 [mm]

[0070] <Feature A> First, an example relating to Feature A will be described. In Examples Al to A6 and Comparative Examples A7 and A8, one of the following three flutes were adopted. - A-flute - B-flute

- E-Flute

[0071] For the top liner and the bottom liner in each of Examples Al to A6 and Comparative Examples A7 and A8, one of the following liner base papers of product numbers "No. 1" to "No. 6" were used. - No. 1: Basis Weight 120 [g/m 2 ], freeness 400 [ml] - No. 2: Basis Weight 160 [g/m 2 ], freeness 400 [ml] - No. 3: Basis Weight 170 [g/m 2 ], freeness 400 [ml] - No. 4: Basis Weight 210 [g/m 2 ], freeness 400 [ml]

[0 - No. 5: Basis Weight 120 [g/m 2 ], freeness 300 [ml] - No. 6: Basis Weight 120 [g/m 2 ], freeness 600 [ml]

[0072] The liner base paper of the product number "No. 1" was manufactured through papermaking by a multilayer paper machine from softwood kraft pulp and corrugated

[5 cardboard used-paper pulp having a freeness of 400 [ml] as raw materials into a corrugated cardboard liner base paper in three layers. The papermaking conditions were that 0.5 [parts by mass] of cationic paper strength agents were added to every total 100 [parts by mass] of the total pulp of the paper layers, and among the pulp on the surface layer, the softwood kraft pulp was contained in a proportion of 10 [mass%]. !o Allof the cationic paper strength agents were contained in the surface layer. The softwood kraft pulp accounted for 6 [mass%] of the total pulp in the paper layers.

[0073] The liner base paper of product number "No. 2" was manufactured by a manufacturing method similar to that of the liner base paper of "No. 1" except that the !s basis weight was changed to 160 [g/m 2]. The liner base paper of product number "No. 3" was manufactured by a manufacturing method similar to that of the liner base paper of "No. 1" except that the proportion of the softwood kraft pulp contained in the pulp of the surface layer was changed to 50 [mass%] and the basis weight was changed to 170 [g/m 2]. The liner base paper of product number "No. 4" was manufactured by a manufacturing method similar to that of the liner base paper of "No. 1" except that the basis weight was changed to 210 [g/m 2].

[0074] The liner base paper of the product number "No. 5" was manufactured by a manufacturing method similar to that of the liner base paper of "No. 1" except that the freeness of the softwood kraft pulp and the corrugated cardboard used-paper pulp was changed to 300 [ml]. The liner base paper of the product number "No. 6" was manufactured by a manufacturing method similar to that of the liner base paper of "No. 1" except that the freeness of the softwood kraft pulp and the corrugated cardboard used-paper pulp was changed to 600 [ml].

[0075]

The "freeness" is a parameter representing the degree to which the pulp forming the raw material of a base paper is beaten. The beating of pulp is a mechanical treatment for beating and grinding (milling) pulp fibers, and is carried out using a well-known refiner (mechanical treatment facility). The value of the freeness can be adjusted by the settings of the refiner. The process of beating the pulp (beating process) is performed immediately before the papermaking process in the manufacturing process of a base paper. In this beating process, a treatment of blending chemical agents into pulp or other treatment is performed in addition to beating of the pulp used for papermaking.

[0 [0076] In each of Examples Al to A6 and Comparative Examples A7 and A8, one medium base paper of the following product numbers "No. 7" and "No. 8" was used for the medium. - No. 7: Basis weight 120 [g/m 2 ] [OND-EM120: manufactured by Oji Materia Co., Ltd.] - No. 8: Basis weight 160 [g/m 2 ] [OND-EM160: manufactured by Oji Materia Co., Ltd.] Each of the measurement corrugated cardboard materials of Examples Al to A6 and Comparative Examples A7 and A8 was a double-faced corrugated cardboard having a total thickness [mm] listed in Table 3.

[0077] !o [Table 3] Examples Comparative Examples

Al A2 A3 A4 A5 A6 A7 A8

Flute A A A A B E A A Product No. 1 No. 2 No. 3 No. 4 No. 2 No. 2 No. 5 No. 6 No. Liner Basis weight 120 160 170 210 160 160 120 120

[g/m 2] Product No. 7 No. 7 No. 7 No. 8 No. 7 No. 7 No. 7 No. 7 No. Medium Basis weight 120 120 120 160 120 120 120 120

[g/m 2] Product No. 1 No. 2 No. 3 No. 4 No. 2 No. 2 No. 5 No. 6 No. Liner Basis weight 120 160 170 210 160 160 120 120 2

[g/m ] Total thickness [mm] 5 5.1 5.1 5.2 3 2 5 5

Freeness [ml] 400 400 400 400 400 400 300 600 E' 2.30x109 2.40x10' 4.82x109 4.76x109 2.30x109 2.30x109 8.95x109 9.60x108 Dynamic EMpa] visco- 2.21x108 2.12x108 1.79x108 1.73x108 2.21x108 2.21x108 1.83x108 1.83x108 elasticity [Mpa] tans 9.61x10-2 8.83x10-2 3.71x10-2 3.63x10-2 9.61x10-2 9.61x10-2 2.04x10-2 1.91x10-'

Stackability B B C C B B D B Crease crack C C B B C C B D property

[0078]

For each of the above Examples Al to A6 and Comparative Examples A7 and A8, the dynamic viscoelasticity listed in Table 3 (values of three parameters, i.e., the elastic modulus E', the loss elastic modulus E", and tan6) was measured. In each of Examples Al to A6 and Comparative Examples A7 and A8, the value of the elastic modulus E'was changed by adjusting the freeness of the liner base paper, so that the value of tan6 was adjusted.

[0079] The dynamic viscoelasticity was measured using a measurement sample piece (measurement piece) cut from each of the measurement corrugated cardboard

[0 materials of Examples Al to A6 and Comparative Examples A7 and A8 according to Steps Al to A5 below.

[0080] Step Al: Cut out a measurement sheet from an arbitrary-selected sheet located above the center sheet, based on the half of the total number of sheets in the

[5 measurement cardboard material (i.e., the center sheet). Specifically, in the case where the total number M of sheets in the measurement corrugated cardboard material was an odd number, a sheet was collected based on the number determined by rounding off the half of the total number of sheets in the measurement corrugated cardboard material M/2 (i.e., the middle sheet). In the case where the total number M of the !o measurement corrugated cardboard materials was an even number, a sheet was collected based on the number of the half of the total number of sheets s in the measurement corrugated cardboard material [(M/2)+l]. Note that sheets without scratches or dents (or having a small number of scratches or dents) were carefully selected when the sheets were collected. !s Step A2: Immerse the measurement sheet sampled in Step Al in tap water for 15

[min]. Step A3: Remove the measurement sheet immersed in Step A2 from tap water, and separate each liner base paper (the top liner and the bottom liner) of the removed measurement sheet by manually separating the liner base papers from the medium base paper so as not to break the liner base papers. Step A4: Dry the liner base papers separated in Step A3 in a dryer at 105 [0] for 20

[min]. Step A5: Cut out a measurement sample piece of the following dimensions from the liner base papers dried in Step A4. > Dimensions - Vertical direction: 5 [mm] - Lateral direction: 30 [mm]

[0081] For the measurement sample pieces cut out in the above Step A5, the dynamic viscoelasticity (the elastic modulus E', the loss elastic modulus E", and tan6) was measured under the following conditions using the following instrument. The measurement sample piece cut out from the liner base paper of the top liner was used for the measurements. Note that there was no difference or there was almost no difference if the measurement sample piece cut out from the liner base paper of the bottom liner was used. > Instrument Dynamic viscometer manufactured by UBM Co., Ltd., model number Rheogel-E4000 > Conditions - Measurement method: Tensile shear mode - Frequency: 100 [Hz] (vibration condition)

[0 - Distortion: 0.10 [%] - Temperature: 25 [°C] (Temperature condition)

[0082] --Evaluation- For Example Al to A6 and Comparative Examples A7 and A8 in which the

[5 dynamic viscoelasticity had been measured as described above, the stackability and the crease crack property to be described next were evaluated. The "stackability" is an evaluation criterion that corresponds to the quality of the packaging style when the measurement corrugated cardboard material is folded zigzag (stacked), and it can also be regarded as the capability to hold the sheets in the folded !o state (folding retention ability). The "crease crack property" is an evaluation criterion that corresponds to the difficulty in being damaged (having crease cracks) at the portions of the creases when the measurement corrugated cardboard material is folded back at the creases. The damage includes cracks, tears, rips, and the like of the liner base papers at the portions !s of the creases. The portions of the creases are areas including the periphery of the creases.

[0083] A measurement corrugated cardboard material to be evaluated was produced by folding a double-faced corrugated cardboard web manufactured by the following manufacturing process into a fan-folded shape in the following folding process. The manufacturing process includes the following Steps B1 to B4. In manufacturing of a double-faced corrugated cardboard web in this manufacturing process, a well-known corrugator including a single facer and a double facer is used.

[0084] - Step B1: Provide a medium base paper fed from a medium base paper roll with a flute shapes (corrugating shapes), and apply an adhesive to the top of the formed flute shapes. - Step B2: Bond a liner base paper for a bottom liner fed from a base paper roll for the bottom liner to the medium base paper to which the adhesive has been applied in Step B1, and bond them together by pressing and heating them with rolls to form a single sided corrugated cardboard web (processing in the single facer).

- Step B3: Bond a liner base paper for a top liner fed from a base paper roll for a top liner to the medium side of the single-sided corrugated cardboard web formed in Step B2 with an adhesive, and bond them together by pressing and heating them with heating rolls to form a double-faced corrugated cardboard web (processing in the double facer). - Step B4: Provide the double-faced corrugated cardboard web produced in Step B3 with creases extending in the width direction and spaced apart at regular intervals in the extending direction.

[0085]

[0 Pressing and heating in the above Steps B2 and B3 are carried out, for example, under the following conditions. > Step B2 (Single facer) - Heating temperature 120 to 200 [°C] - Roll linear load 20 to 40 [kN/m]

[5 - Pressing time 0.01 to 0.20 [sec] > Step B3 (Double facer) - Heating temperature 120 to 200 [°C] - Roll linear load 0.1 to 1.0 [kN/m] - Pressing time 2 to 7 [sec] !o [0086] A commonly used one-tank type starch paste was used as the adhesive for bonding the liner base papers and the medium base paper in Steps B1 and B2. Note that an emulsion such as a synthetic resin may be used for bonding the liner base papers and the medium base paper. Specific examples of the synthetic resin !s include polyethylene, polypropylene, polyamides, polyesters, ethylene-unsaturated carboxylic acid copolymers, styrene-butadiene copolymers, butadiene-acrylonitrile copolymers, styrene-butadiene-acrylonitrile copolymers, polyvinyl acetate, ethylene vinyl acetate copolymers, polyacrylic acid ester copolymers, and styrene-acrylic acid ester copolymers.

[0087] In addition, as the method of bonding the liner base papers and the medium base paper in Steps B1 and B2, a method of forming an adhesive layer by providing the liner base papers or the medium base paper with application, such as an extrusion lamination or coating with a synthetic resin emulsion, and then causing polymerization on the liner base papers and the medium base paper, or a method of forming a synthetic resin film between the liner base papers and the medium base paper, and pressing and heating them may be employed.

[0088] The double-faced corrugated cardboard web manufactured in the manufacturing process described above is folded zigzag in a folding process including the following Steps C1 and C2. In this folding process, the following folding apparatus is used under the following conditions.

- Folding apparatus: manufactured by BHS Corrugated Machinery Product No. "AS-F", - Transfer speed: 100 [m/min] - Step Cl: After Step B4, transfer the produced double-faced corrugated cardboard web to the folding apparatus described above (see conveyance part 50A in FIG. 2). - Step C2: Alternately fold back the double-faced corrugated cardboard web transported in Step C1 at creases into a fan-folded shape to thereby prepare a measurement corrugated cardboard material folded zigzag with the package dimensions described above (see the folding part 50B and the stacking part 50C in FIG.

[0 2).

[0089] In the evaluation of the stackability, the appearance of the measurement corrugated cardboard material prepared in the above Step C2 was visually checked and evaluated by the following criteria. 1s - B: Production of a measurement corrugated cardboard material was possible, and there was no space [see the reference symbol S in FIG. 3B] at any of the creases. - C: Production of a measurement corrugated cardboard material was possible, but there was space [see the reference symbol S in FIG. 3B] at one or more creases. - D: A measurement corrugated cardboard material could not be prepared. !o In the evaluation of stackability, the evaluation of "C" or more was regarded as a good evaluation.

[0090] In an evaluation of the crease crack property, the measurement corrugated cardboard material prepared in the above Step C2 was visually checked to determine !s whether or not a crease crack occurred at the portions of the creases, and the confirmation result was evaluated by the following criteria. As described above, the "portions of the creases" are areas including the periphery of the creases. - B: No crease crack was found in any of the creases. - C: One or more crease cracks were found in one or more creases in a part of the width direction. - D: One or more crease cracks were found in one or more creases across the entire width direction. In the evaluation of the crease crack property, the evaluation of "C" or more was regarded as a good evaluation.

[0091] In Examples Al to A6, the elastic modulus E'was 1.00 x 109 [Mpa] or more and 8.00 x 109 [Mpa] or less and tan6 was 2.50 x 10-2 or more and 1.50 x 10-1 or less, and the stackability and the crease crack property evaluation were evaluated to be "C" or more. In particular, in Examples Al, A2, A5, and A6 in which the elastic modulus E' was 3.00 x 109 [Mpa] or less and tan6 was 7.00 x 10-2 or more, the stackability was evaluated to be "B" although the crease crack property was evaluated to be "C".

Further, in Examples A3 and A4 in which the elastic modulus E'was 4.00 x 109

[Mpa] or more and tan6 was 4.00 x 10-2 or less, the crease crack property was evaluated to be "B" although the stackability was evaluated to be "C".

[0092] In contrast, in Comparative Examples A7 and A8 in which the elastic modulus E' was less than 1.00 x 109 [Mpa] or was more than 8.00 x 109 [Mpa], and tan6 is less than 2.50 x 10-2 or was more than 1.50 x 10-1, the stackability or the crease crack property was evaluated to be "D". In Comparative Example A7 in which the elastic modulus E'was more than 8.00

[0 x 109 [Mpa] and tan6 is less than 2.50 x 10-2, the stackability was evaluated to be "D" although the crease crack property was evaluated to be "B". Further, in Comparative Example A8 in which the elastic modulus E'was less than 1.00 x 109 [Mpa] and tan6 was more than 1.50 x 10-1, the stackability was evaluated to be "D" although the stackability was evaluated to be "B".

[0093] In view of Comparative Examples A7 and A8, it can be said from Examples Al to A6 that opening of folds at the crease are suppressed and crease cracks at the creases are suppressed when the measurement corrugated material is folded back at the creases if the elastic modulus E' is 1.00 x 109 [Mpa] or more and 8.00 x 109 [Mpa] or !o less and tan6 is 2.50 x 10-2 or more and 1.50 x 10-1 or less. Further, it can be said from Examples Al, A2, A5, and A6 that opening of folds at the creases can be prevented when the measurement corrugated material is folded back at the creases if the elastic modulus E' is 3.00 x 109 [Mpa] or less and tan6 is 7.00 x 10-2 or more. It can be said from Examples A3 and A4 that crease cracks at the

!s creases can be prevented when the measurement corrugated material is folded back at the creases if the elastic modulus E' is 4.00 x 109 [Mpa] or more and tan6 is 4.00 x 10-2 or less.

[0094] It is inferred from Comparative Example A7 that the pulp fibers forming the liner base paper do not remain stretched and the repulsive force to open the folds increases, resulting in poor stackability, when the elastic modulus E' is more than 8.00 x 109 [Mpa] tan6 is less than 2.50 x 10-2. It is inferred from Comparative Example A8 that an external force due to bending is applied to the creases F while the pulp fibers forming the liner base paper are stretched, resulting in poor crease crack property, when the elastic modulus E' is less than 1.00 x 109 [Mpa] and tan6 is more than 1.50 x 10-1.

[0095] In addition, it can be seen from Comparative Example A7 in which the value of the freeness was smaller than those of Examples Al to A6 and Comparative Example A8 in which the value of the freeness was larger than those of Examples Al to A6, that the value of the elastic modulus E' increases and the value of tan 6 decreases as the value of the freeness decreases, and the value of the elastic modulus E' decreases and the value of tan 6 increases as the value of the freeness increases. In view of Comparative Example A7 and A8, it can be said from Examples Al to A6 that the elastic modulus E' is adjusted within the range of 1.00 x 109 [Mpa] or more and 8.00 x 109 [Mpa] or less and tan 6 is adjusted within the range of 2.50 x 10-2 or more and 1.50 x 10-1 or less when the value of the freeness is 350 [ml] or more and 500

[ml] or less.

[0096] Of Examples Al to A6 having the same values of the freeness, it is inferred

[0 from Example A3 in which the proportion of the softwood kraft pulp and the basis weight of the liner base papers were different from that in Example Al, and from Example A4 in which the basis weight of the liner base papers was different from that in Example 1 that the value of the elastic modulus E' tends to increase and the value of tan 6 tends to decrease as the proportion of the softwood kraft pulp or the basis weight of the liner base papers increases. It is inferred from Examples Al to A6 that the loss elastic modulus E" is preferably within the range of 1.50 x 108 [Mpa] or more and 2.50 x 108 [Mpa] or less.

[0097] <Feature B> !o Next, Examples related to the Feature B will be described.

[0098] In Examples B1 to B19 and Comparative Examples B20 to B29, one of the following three flutes were adopted. - A-Flute (single wall), total thickness: 5.0 [mm] !s - E-Flute (single wall), total thickness: 1.5 [mm] - AB-Flute (double wall), total thickness: 8.5 [mm]

[0099] For the top liner and the bottom liner in each of Examples B1 to B19 and Comparative Examples B20 to B29, one of the following liner base papers of product numbers "No. 1" to "No. 25" were used for the top liner and the bottom liner. The liner base papers of product numbers "No. 1" to "No. 15" each have the following basis weight and density. - No. 1: Basis weight 120 [g/m 2 ], density 0.8 [g/cm 3 - No. 2 and Nos. 6 to 25: Basis weight 170 [g/m 2 ], density 0.8 [g/cm 3 - No. 3: Basis weight 210 [g/m 2 ], density 0.8 [g/cm 3 - No. 4: Basis weight 280 [g/m 2 ], density 0.8 [g/cm 3 - No. 5: Basis weight 170 [g/m 2 ], density 0.6 [g/cm 3

[0100] The liner base paper of the product number "No. 1" was manufactured through papermaking by a multilayer paper machine from softwood kraft pulp and corrugated cardboard used-paper pulp having a freeness of 300 [ml] as raw materials into a corrugated cardboard liner base paper in three layers under the following papermaking conditions. The freeness was measured by the following measuring apparatus in accordance with JIS P8121 2012. - Measurement apparatus: Product name "Canadian Standard Freeness", KUMAGAI RIKI KOGYO Co., Ltd., Product number "No. 2580-A"

[0101] - Papermaking conditions of product number "No. 1" > Sizing agent: a chemical agent having the name "Size Pine N-830 (manufactured by Arakawa Chemical Industries, Ltd.)" ("a" in Tables 4 to 7 below) was contained in an amount of 0.3 [parts by mass] per every total 100 [parts by mass] of the total pulp of the

[0 paper layers > Paper strength agent: a chemical agent having the name "PT-1001 (manufactured by Arakawa Chemical Industries, Ltd.)" was contained in an amount of 0.2 [parts by mass] per every total 100 [parts by mass] of the total pulp of the paper layers

[5 > Sulfuric acid band: contained in 5 [parts by mass] per every total 100 [parts by mass] of the total pulp of the paper layers > Softwood kraft pulp: contained in a proportion of 10 [mass%] of the pulp fibers in the surface layer. The softwood kraft pulp accounted for 6 [mass%] of the total pulp in the paper layers. !o > Amount of fine fibers: 33 [%] of the pulp fibers forming the liner. The surface layer among the three layers of the liner base papers was prepared under the above papermaking conditions. The papermaking conditions of the middle layer and the back layer among the three layers of the liner base papers are not limited to the above papermaking conditions. !s [0102] The liner base paper of product number "No. 2" was manufactured by a manufacturing method similar to that of the liner base paper of "No. 1" except that the basis weight was changed to 170 [g/m 2]. The liner base paper of product number "No. 3" was manufactured by a manufacturing method similar to that of the liner base paper of "No. 1" except that the basis weight was changed to 210 [g/m 2]. The liner base paper of product number "No. 4" was manufactured by a manufacturing method similar to that of the liner base paper of "No. 1" except that the basis weight was changed to 280 [g/m 2].

[0103] Each of the liner base papers of product numbers "No. 5" to "No. 25" was manufactured by a manufacturing method similar to that of the liner base paper of "No. 2" except for the following. - No. 5: The density was changed to 0.6 [g/cm 3] - No. 6: The amount of fine fibers was changed to 25 [%], and the length mean fiber length was changed to 1.08 [mm]

- No. 7: The amount of fine fibers was changed to 45 [%], and the length mean fiber length was changed to 0.95 [mm] - No. 8: The proportion of the softwood kraft pulp contained in the pulp of the surface layer was changed to 20 [mass%], and the length mean fiber length was changed to 1.50 [mm]

[0104] - No. 9: The amount of the sizing agent added was changed to 3 [parts by mass] - No. 10: The amount of the sizing agent added was changed to 5 [parts by mass] - No. 11: The sizing agent was changed to a chemical agent having the name "Size

[0 Pine NT-78 (manufactured by Arakawa Chemical Industries, Ltd.)" ("P" in Tables 4 to 7 below) - No. 12: The sizing agent was changed to a chemical agent having the name "Size Pine K-287 (manufactured by Arakawa Chemical Industries, Ltd.)" ("y" in Tables 4 to 7 below) - No. 13: The amount of paper strength agent added was changed to 1.5 [parts by mass]

[0105] - No. 14: The amount of the paper strength agent added was changed to 3.0 [parts by mass] !o - No. 15: The amount of fine fibers was changed to 38 [%], and the length mean fiber length was changed to 0.98 [mm] - No. 16: The proportion of the corrugated cardboard used-paper pulp contained in the pulp of the surface layer was changed to 100 [mass%] - No. 17: The amount of fine fibers was changed to 45 [%], the length mean fiber !s length was changed to 0.95 [mm], and the amount of sizing agent added was changed to 5.0 [parts by mass]

[0106] - No. 18: The amount of fine fibers was changed to 20 [%], and the length mean fiber length was changed to 1.12 [mm] - No. 20: The amount of fine fibers was changed to 50 [%], and the length mean fiber length was changed to 0.94 [mm] - No. 20: The proportion of the softwood kraft pulp contained in the pulp of the surface layer was changed to 20 [mass%], and the length mean fiber length was changed to 1.60 [mm] - No. 21: No sizing agent was added

[0107] - No. 22: The amount of the sizing agent added was changed to 8.0 [part by mass] - No. 23: No paper strength agent was added - No. 24: The amount of the paper strength agent added was changed to 5.0 [parts by mass] - No. 25: The proportion of the softwood kraft pulp contained in the pulp of the surface layer was changed to 20 [mass%], the amount of the sizing agent added was changed to 8.0 [parts by mass], the amount of fine fibers was changed to 50 [%], and the length mean fiber length was changed to 1.60 [mm]

[0108] For measuring the content concentrations of chemical agents such as the sizing agent and the paper strength agent contained in the liner base papers, the content concentration of each chemical agent (the ratio relative to the pulp weight) was measured using a pyrolysis gas chromatograph mass spectrometer (pyrolysis apparatus: PY-2020D manufactured by Frontier Laboratories Ltd., gas chromatograph mass spectrometer: 5973N manufactured by Agilent Technologies, Inc.).

[0 The above liner base papers to be analyzed were peeled off from the medium base paper by the following Steps D1 to D2, and the liner base papers were dried and then pulverized by a pulverizer. Two samples of 200 to 300 [pg] of the pulverized product were analyzed using the pyrolysis gas chromatograph mass spectrometer.

[0109]

[5 In the above pyrolysis gas chromatograph mass spectrometer, a peak was extracted with reference to a peak of the target chemical agent obtained when a calibration curve was prepared, the peak area was read, and the read peak area was compared against the above calibration curve, whereby the content concentration of the target chemical agent was calculated. !o The measurement was performed twice for each sample, and the average value was determined to be used as the content concentration of the chemical agent (the ratio relative to the pulp weight). It is to be noted that each chemical agent was impregnated into filter papers (manufactured of ADVANTEC, CO., LTD., circular qualitative filter paper, No. 2), so that !s the contents of the chemical agent were 0.01 [%], 0.1 [%], 1 [%], 5 [%], and 10 [%] by weight and then dried, which were used as samples for a calibration curve. Each sample for a calibration curve was milled, and 200 to 300 [pg] of the milled product were analyzed by the pyrolysis gas chromatograph mass spectrometer to generate the above calibration curve.

[0110] In the above product number "No. 5", the density was changed by adjusting the nip pressure of the multilayer paper machine. In the above product numbers "No. 6" to "No. 8", "No. 15", "No. 17" to "No. 20", and "No. 25", the amount of fine fibers and the length mean fiber length were adjusted using a fiber classifier (MAX-F700, manufactured by AIKAWA Iron Works Co., Ltd.). In the product numbers "No. 7" and "No. 17", pulp fibers other than fine fibers were removed using the fiber classifier.

[0111] In each of Examples B1 to B19 and Comparative Examples B20 to B29, one medium base paper of the following product numbers "No. 26" and "No. 27" was used for the medium.

- No. 26: Basis weight 120 [g/m 2], density 0.65 [g/cm 3] [OND-EM120: manufactured by Oji Materia Co., Ltd.] - No. 27: Basis weight 160 [g/m 2], density 0.65 [g/cm 3] [OND-EM160: manufactured by Oji Materia Co., Ltd.] For each of Examples B1 to B19 and Comparative Examples B20 to B29 above, the liner fiber information listed in Tables 4 to 7 was measured. The measured values of various parameters such as the density, the length mean fiber length, the fine fibers, and the basis weight, as well as the parts by mass of the sizing agent and the paper strength agent may have measurement errors of plus or minus 10%.

[0 [0112]

[Table 4] Examples BI B2 B3 B4 B5 B6 B7 A A A A E AB A Product No. - No. 1 No. 2 No. 3 No. 4 No. 2 No. 2 No. 5 Liner Basis g/m 2 /g/cm 3 weight/densit 120/0.8 170/0.8 210/0.8 280/0.8 170/0.8 170/0.8 170/0.6 y Product No. - - - - - - No. 27 Medium Basis 160/0.6 (1) weight/densit g/m 2 /g/cm 3 - - - -

y Product No. - No. 26 No. 27 No. 27 No. 27 No. 27 No. 27 No. 27 Middle Basis liner weight/densit g/m 2 /g/cm 3 120/0.6 160/0.6 160/0.6 160/0.6 160/0.6 160/0.6 160/0.5 5 5 5 5 5 5 y Product No. - - - - - - No. 27 Medium Basis 2 3 (2) weight/densit g/m /g/cm - - - - - 160/0.6 y Product No. - No. 1 No. 2 No. 3 No. 4 No. 2 No. 2 No. 5 Liner Basis g/m 2 /g/cm 3 weight/densit 120/0.8 170/0.8 210/0.8 280/0.8 170/0.8 170/0.8 170/0.6 y Amount parts by 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Sizig added mass agent Type - aa a a a a a Paper Amut prsb strength Amount pasb 0.2 0.2 0.2 0.2 0.2 0.2 0.2 agent Runkel ratio - 1.4 1.4 1.4 1.4 1.4 1.4 1.4

Liner fiber Length mean mm 1.00 1.00 1.00 1.00 1.00 1.00 1.00 info. fiber length

Fine fibers % 33 33 33 33 33 33 33 Total thickness mm 5 5 5 5 1.5 8.5 5 Temperature and humidity 3 3 3 3 3 4 3 condition B Load test Temperature and humidity 3 3 3 3 3 3 3 condition A

[0113]

[Table 5] Examples B8 B9 B1O Bl B12 B13 B14 A A A A A A A Product No. - No. 6 No. 7 No. 8 No. 9 No. 10 No. 11 No. 12 Liner Basis weight/densit g/m 2 /g/cm 3 170/0.8 170/0.8 170/0.8 170/0.8 170/0.8 170/0.8 170/0.8 y ProductNo. - - - - - - - Medium Basis 3 (1) weight/densit g/m 2 /g/cm - - - - - -

y Product No. - No. 27 No. 27 No. 27 No. 27 No. 27 No. 27 No. 27 Middle Basis liner weight/densit g/m2 g/cm3 160/0.6 160/0.6 160/0.6 160/0.6 160/0.6 160/0.6 160/0.6 5 5 5 5 5 5 5 y ProductNo. - - - - - - - Medium Basis (2) weight/densit g/m 2 /g/cm 3 - - - - - -

y Product No. - No. 6 No. 7 No. 8 No. 9 No. 10 No. 11 No. 12 Liner Basis g/m 2 /g/cm 3 weight/densit 170/0.8 170/0.8 170/0.8 170/0.8 170/0.8 170/0.8 170/0.8 y Amount parts by 0.3 0.3 0.3 1 3 0.3 0.3 Sizig added mass agent Type - a a a a y Paper Amut prsb strength Amount pmasb 0.2 0.2 0.2 0.2 0.2 0.2 0.2 agent Runkel ratio - 1.4 1.4 1.43 1.4 1.4 1.4 1.4

Liner fiber Length mean mm 1.08 0.95 1.50 1.00 1.00 1.00 1.00 info. fiber length

Fine fibers % 25 45 33 33 33 33 33 Total thickness mm 5 5 5 5 5 5 5 Temperature and humidity 4 3 4 4 4 3 3 condition B Load test Temperature and humidity 3 4 4 4 4 3 3 condition A

[0114]

[Table 6] Examples Comparative Examples B15 B16 B17 B18 B19 B20 B21 A A A A A A A Product No. - No. 13 No. 14 No. 15 No. 16 No. 17 No. 18 No. 19 Liner Basis 170/0.8 weight/densit g/m 2 /g/cm 3 170/0.8 170/0.8 170/0.8 3 170/0.8 170/0.8 170/0.8 y ProductNo. - - - - - - - Medium Basis 2 3 (1) weight/densit g/m /g/cm - - - - - -

y Product No. - No. 27 No. 27 No. 27 No. 27 No. 27 No. 27 No. 27 Middle Basis liner Mide weight/densit Batsi g/m 2 /g/cm33 160/0.6 5 160/0.6 5 55555 160/0.6 160/0.6 160/0.6 160/0.6 160/0.6 55 5 5 5 5 5 y ProductNo. - - - - - - - Medium Basis (2) weight/densit g/m 2 /g/cm 3 - - - - - -

y Product No. - No. 13 No. 14 No. 15 No. 16 No. 17 No. 18 No. 19 Liner Basis 170/08 weight/densit g/m 2 /g/cm 3 170/0.8 170/0.8 170/0.8 3 170/0.8 170/0.8 170/0.8 y Amount parts by 0.3 0.3 0.3 0.3 3 Sizing 0.3 0.3 added mass agent Type - aa a a a a a Paper Amut )rsb strength Amount pasb 1.5 3 0.2 0.2 0.2 0.2 0.2 agent Runkel ratio - 1.4 1.4 1.45 1.36 1.4 1.4 1.4

Liner fiber Length mean mm 1.00 1.00 0.98 0.92 0.95 1.12 0.94 info. fiber length

Fine fibers % 33 33 38 33 45 20 50 Total thickness mm 5 5 5 5 5 5 5 Temperature and humidity 5 5 3 3 4 5 1 condition B Load test Temperature and humidity 4 5 3 3 5 2 2 condition A

[0115]

[Table 7] Comparative Examples B22 B23 B24 B25 B26 B27 B28 B29 E AB A A A A A A Product No. - No. 19 No. 19 No. 20 No. 21 No. 22 No. 23 No. 24 No. 25 Liner Basis g/m 2 /g/cm 3 weight/densit 170/0.8 170/0.8 170/0.8 170/0.8 170/0.8 170/0.8 170/0.8 170/0.8 y Product No. - - No. 27 - - - - - Medium Basis 160/0.6 (1) weight/densit g/m 2 /g/cm 3 y Product No. - No. 27 No. 27 No. 27 No. 27 No. 27 No. 27 No. 27 No. 27 Middle Basis liner weight/densit g/m2 g/cm3 160/0.6 160/0.6 160/0.6 160/0.6 160/0.6 160/0.6 160/0.6 160/0.6 5 5 5 5 5 5 5 5 y Product No. - - No. 27 - - - - - Medium Basis 2 3 (2) weight/densit g/m /g/cm 160/0.6

y Product No. - No. 19 No. 19 No. 20 No. 21 No. 22 No. 23 No. 24 No. 25 Liner Basis g/m 2 /g/cm 3 weight/densit 170/0.8 170/0.8 170/0.8 170/0.8 170/0.8 170/0.8 170/0.8 170/0.8 y Amount parts by 0.3 0.3 0.3 0 5 0.3 0.3 5 Sizig added mass agent Type - aa a - a a a a Paper Amut prsb strength Amount pasb 0.2 0.2 0.2 0.2 0.2 0 5 0.2 agent Runkel ratio - 1.4 1.4 1.45 1.4 1.4 1.4 1.4 1.45

Liner fiber Lengthn mm 0.94 0.94 1.60 1.00 1.00 1.00 1.00 1.60

Fine fibers % 50 50 33 33 33 33 33 50 Total thickness mm 1.5 8.5 5 5 5 5 5 5 Temperature and humidity 1 2 4 2 2 2 2 3 condition B Load test Temperature and humidity 2 2 2 1 2 2 2 1 condition A

[0116] The "liner fiber information" is information measured on pulp fibers constituting a liner base paper, and includes three types of information: "Runkel ratio", "length mean fiber length", and "amount of fine fibers". The Runkel ratio is a parameter indicating the shape of pulp fibers, and is calculated as (Runkel ratio) = (fiber wall thickness x 2) / (fiber pore diameter). A larger Runkel ratio indicates fibers with higher rigidity. The length mean fiber length is the average of the lengths of pulp fibers constituting a liner (fiber lengths). The amount of fine fibers is the proportion [%] of the amount of contained fine fibers relative to the total pulp fibers (taken to be 100 [%]) constituting a liner. The fine fibers are fine fibers having fiber lengths of 0.0 [mm] or more and 0.2 [mm] or less.

[0117]

The three types of "liner fiber information" of "Runkel ratio", "length mean fiber length", and "amount of fine fibers" were measured in the following Steps D1 to D5. Step D1: Cut the corrugated cardboard material of the second uppermost into a 40

[cm] square, and use the 40 [cm] square corrugated cardboard sheet for measurement. The cut position was at the middle in the corrugated cardboard sheet width. Then, immerse the corrugated cardboard sheet in ion-exchanged water for 15 minutes and remove it from the ion-exchanged water. Step D2: Separate each liner base paper (the top liner and the bottom liner) of the corrugated cardboard sheet removed in Step D1 from the medium base paper by

[0 manually separating the liner base papers so as not to break the liner base papers. Step D3: Immerse each of the liner base papers and the medium base paper separated in Step D2 in ion-exchanged water for 24 hours with the adjusted concentration of 2%. Step D4: After immersing each of the liner base papers and the medium base paper

[5 with the adjusted concentration in Step D3 for 24 hours, perform dissociation by using a standard type disintegrator (manufactured by KUMAGAI RIKI KOGYO Co., Ltd.) for 20 minutes to decompose the pulp into a fibrous form. Step D5: Separate the slurry (pulp fiber) after the dissociation in Step D4, and measure the "Runkel ratio", the "length mean fiber length", and the "amount of fine !o fibers" by using the following fiber length measurement device. - Fiber length measurement device: Product number FS-5 UHD base unit, manufactured by Valmet

[0118] --Evaluation- !s The fragility of an evaluation box was evaluated on Examples B1 to B19 and Comparative Examples B20 to B29 in which the "Runkel ratio", the "length mean fiber length", and the "amount of fine fibers" had been measured as described above. The term "fragility" is an evaluation criterion that corresponds to the largeness of the load bearing capacity against the contents contained in the box. The fragility was evaluated in a load test according to Steps El to E6 below. - Step El: Punch the measurement corrugated cardboard material into a development pattern of an evaluation box having the following shape and size with a sample cutter (manufactured by Mimaki Engineering Co., Ltd., CF2-1218). > Shape: Pattern of a developed RSC corrugated cardboard box > Size: Width of side plates of the RSC corrugated cardboard box 356 [mm], Width of end plates of the RSC corrugated cardboard box 159 [mm], Height of the RSC corrugated cardboard box 256 [mm] - Step E2: Manually form creased lines (creases) having the following depth to the regions that are to define the bottom surface of the evaluation box in the development pattern punched in Step El with the following ruling jig, and assemble the evaluation box manually.

> Ruling jig: R rule (creased line width 2 [mm], manufactured by NIPPON DIE STEEL CO., LTD.) > Depth of creased line: Recessed with a depth of 50 [%] of the total thickness of the measurement corrugated cardboard material - Step E3: Treat the evaluation box assembled in Step E2 under the following temperature and humidity condition A for 1 [hour]. > Temperature and humidity condition A: Temperature of 30 [°C], humidity of 90

[%Rh] - Step E4: After treating in Step E3, place a weight of 15 [kg] in weight in the t0 evaluation box under the above temperature and humidity condition A. Note that the weight is placed so that the load is applied to the entire bottom surface of the evaluation box. - Step E5: After Step E4, two operators lift up the evaluation box and keep for 30 [sec]. - Step E6: Visually check whether or not the evaluation box was ripped in Step E5.

[5 [0119] The fragility described above was evaluated according to the following criteria. - 5: The bottom surface of the evaluation box did not changed at all. - 4: Although the bottom surface of the evaluation box was not ripped, the bottom surface (inner liner of the evaluation box) had a dent or bend. !o - 3: Although the bottom surface of the evaluation box was not ripped, the bottom surface (both inner and outer liners of the evaluation box) had a dent or bend. - 2: The bottom surface of the evaluation box (inner liner of the evaluation box) was ripped. - 1: The evaluation box was severely ripped while being lifted and kept, and the !s weight fell from the evaluation box. Of the above criteria, "3" or more was regarded as a good evaluation and "2" or less was regarded as a bad evaluation.

[0120] The load test under the above temperature and humidity condition A is an evaluation of the fragility of the evaluation box under a humid condition (wet test). In addition to the wet test, for each of the measurement corrugated cardboard materials of Examples B1 to B19 and Comparative Examples B20 to B29, the fragility of an evaluation box is also evaluated in a load test under the dry condition of the following temperature and humidity condition B (dry test). > Temperature and humidity condition B: Temperature 23 [°C], humidity 50 [%Rh] The dry test was similar to the test of Steps El to E6 above except that the temperature and humidity condition A was changed to the above temperature and humidity condition B in Steps E3 and E4.

[0121] In Examples B1 to B19, the amount of the sizing agent added was 0.2 [parts by mass] or more and 4.0 [parts by mass] or less, the amount of the paper strength agent added was 0.1 [parts by mass] or more and 4.0 [parts by mass] or less, the length mean fiber length of the pulp fibers was 0.90 [mm] or more and 1.55 [mm] or less, the amount of fine fibers was 23 [%] or more and 48 [%] or less, the fragility was evaluated to be "3" or more under both of the temperature and humidity conditions A and B, and the evaluation boxes were not ripped and the weight did not fall.

[0122] In Example B11, B12, and B19 in which the amount of the sizing agent added was 0.8 [parts by mass] or more, Example B15 and B16 in which the amount of the paper strength agent added was 1.0 [parts by mass] or more, Example 10 in which the length mean fiber length was 1.50 [mm] or more, and Examples B9 and B19 in which

[0 the amount of fine fibers was 40 [%] or more, the fragility was evaluated to be "4" or more under the temperature and humidity condition A.

[0123] In contrast, in Comparative Examples B20 to B29 in which the amount of the sizing agent added was less than 0.2 [parts by mass] or was more than 4.0 [parts by

[5 mass], the amount of the paper strength agent added was less than 0.1 [parts by mass] or was more than 4.0 [parts by mass], the length mean fiber length of the pulp fibers was less than 0.90 [mm] or was more than 1.55 [mm], or the amount of fine fibers was less than 23 [%] or was more than 48 [%], the fragility was evaluated to be "2" or less under at least the temperature and humidity condition A. !o [0124] In view of Comparative Examples B20 to B29, it can be said from Examples B1 to B19 that ripping (damages) is suppressed in a box manufactured using a measurement corrugated cardboard material when the amount of the sizing agent added is 0.2 [parts by mass] or more and 4.0 [parts by mass] or less, the amount of the !s paper strength agent added is 0.1 [parts by mass] or more and 4.0 [parts by mass] or less, the length mean fiber length of the pulp fibers is 0.90 [mm] or more and 1.55 [mm] or less, and the amount of fine fibers is 23 [%] or more and 48 [%] or less. Furthermore, it can be said from Examples B9, B10, B11, B12, B15, B16, and B19 that ripping (damages) can be prevented under a humid condition when any one of the following is satisfied: the amount of the sizing agent added is 0.8 [parts by mass] or more, the amount of the paper strength agent added is 1.0 [parts by mass] or more, the length mean fiber length is 1.50 [mm] or more, and the amount of fine fibers is 40 [%] or more.

[0125] It is inferred from Comparative Examples B26 and B29 that the sizing agent inhibits hydrogen bonding between the fibers, resulting in a reduction in the strength and an increase in the fragility of the liners under a humid condition when the amount of the sizing agent added is more than 4.0 [parts by mass]. It is inferred from Comparative Example B28 that the paper strength agent is aggregated, resulting in a reduction in the strength and an increase in the fragility of the liners when the amount of the paper strength agent added is more than 4.0 [parts by mass].

It is inferred from Comparative Examples B24 and B29 that spaces between long fibers increase, which makes water to be easily absorbed, resulting in a reduction in the strength and an increase in the fragility of the liners under a humid condition when the length mean fiber length is more than 1.55 [mm]. It is inferred from Comparative Example B20 that spaces between long fibers increase, which makes water to be easily absorbed, resulting in a reduction in the strength and an increase in the fragility of the liners under a humid condition when the amount of fine fibers is less than 23 [%]. It is inferred from Comparative Examples B21 to B23 and B29 that the amount

[0 of long fibers is reduced and entanglement of pulp fibers reduces, resulting in a reduction in the strength and an increase in the fragility of the liners when the amount of fine fibers was more than 48 [%].

[0126] <Feature C>

[5 Next, Examples related to Feature C will be described. Measurement corrugated cardboard materials in Examples relating to Feature C were manufactured by the operator who manually folded a corrugated cardboard web extending in a band shape into a fan-folded shape to the size described above.

[0127] !o In Examples C1 to C11 and Comparative Examples C12 to C19, one of the following three flutes were adopted. - A-Flute (single wall), total thickness: 5.0 [mm] - E-Flute (single wall), total thickness: 1.5 [mm] - AB-Flute (double wall), total thickness: 8.2 [mm] !s [0128] For the top liner and the bottom liner in each of Examples C1 to C11 and Comparative Examples C12 to C19, one of the following liner base papers of product numbers "No. 1" to "No. 15" were used for the top liner and the bottom liner. The liner base papers of product numbers "No. 1" to "No. 15" each have the following basis weight and density. - No. 1: Basis weight 120 [g/m 2 ], density 0.8 [g/cm 3 - No. 2 and Nos. 6 to 11: Basis weight 170 [g/m 2 ], density 0.8 [g/cm 3 - No. 3: Basis weight 210 [g/m 2 ], density 0.8 [g/cm 3 - No. 4: Basis weight 280 [g/m 2 ], density 0.8 [g/cm 3 - No. 5: Basis weight 170 [g/m 2 ], density 0.7 [g/cm 3 - Nos. 12 and 14: Basis weight 170 [g/m 2 ], density 0.5 [g/cm 3 - Nos. 13 and 15: Basis weight 170 [g/m 2 ], density 0.9 [g/cm 3

[0129] The liner base paper of the product number "No. 1" was manufactured through papermaking by a multilayer paper machine from softwood kraft pulp and corrugated cardboard used-paper pulp having a freeness of 400 [ml] as raw materials into a corrugated cardboard liner base paper in three layers under the following papermaking conditions. The freeness was measured by the following measuring apparatus in accordance with JIS P8121 2012. - Measurement apparatus: Product name "Canadian Standard Freeness", KUMAGAI RIKI KOGYO Co., Ltd., Product number "No. 2580-A"

[0130] - Papermaking conditions of product number "No. 1" > Sizing agent: a chemical agent having the name "Size Pine N-830 (manufactured by Arakawa Chemical Industries, Ltd.)" was contained in an amount of 0.3 [parts by mass] per every total 100 [parts by mass] of the total pulp of the paper layers

[0 > Paper strength agent: a chemical agent having the name "PT-1001 (manufactured by Arakawa Chemical Industries, Ltd.)" was contained in an amount of 0.5 [parts by mass] per every total 100 [parts by mass] of the total pulp of the paper layers > Sulfuric acid band: contained in 5 [parts by mass] per every total 100 [parts by

[5 mass] of the total pulp of the paper layers > Softwood kraft pulp: contained in a proportion of 10 [mass%] of the pulp fibers in the surface layer. The softwood kraft pulp accounted for 6 [mass%] of the total pulp in the paper layers. > Amount of fine fibers: 36.7 [%] of the pulp fibers forming the liner. !o The surface layer among the three layers of the liner base papers was prepared under the above papermaking conditions. The papermaking conditions of the middle layer and the back layer among the three layers of the liner base papers are not limited to the above papermaking conditions.

[0131] !s The liner base paper of product number "No. 2" was manufactured by a manufacturing method similar to that of the liner base paper of "No. 1" except that the basis weight was changed to 170 [g/m 2]. The liner base paper of product number "No. 3" was manufactured by a manufacturing method similar to that of the liner base paper of "No. 1" except that the basis weight was changed to 210 [g/m 2]. The liner base paper of product number "No. 4" was manufactured by a manufacturing method similar to that of the liner base paper of "No. 1" except that the basis weight was changed to 280 [g/m 2].

[0132] Each of the liner base papers of product numbers "No. 5" to "No. 15" was manufactured by a manufacturing method similar to that of the liner base paper of "No. 2" except for the following. - No. 5: The density was changed to 0.7 [g/cm 3] - No. 6: The amount of fine fibers was changed to 16.5 [%] - No. 7: The amount of fine fibers was changed to 19.8 [%] - No. 8: The amount of fine fibers was changed to 26.8 [%]

- No. 9: The proportion of the softwood kraft pulp contained in the pulp of the surface layer was changed to 20 [mass%], and the length mean fiber length was changed to 1.50 [mm]

[0133] - No. 10: The amount of fine fibers was changed to 13.9 [%] - No. 11: The amount of fine fibers was changed to 40.1 [%] - No. 12: The density was changed to 0.5 [g/cm 3] - No. 13: The density was changed to 0.9 [g/cm 3] - No. 14: The amount of fine fibers was changed to 13.9 [%], and the density was t0 changed to 0.5 [g/cm 3] - No. 15: The proportion of the softwood kraft pulp contained in the pulp of the surface layer was changed to 20 [mass%], the amount of fine fibers was changed to 40.1 [%], and the density was changed to 0.9 [g/cm 3]

[0134]

[5 For measuring the content concentrations of chemical agents such as the sizing agent and the paper strength agent contained in the liner base papers, the content concentration of each chemical agent (the ratio relative to the pulp weight) was measured using a pyrolysis gas chromatograph mass spectrometer (pyrolysis apparatus: PY-2020D manufactured by Frontier Laboratories Ltd., gas chromatograph !o mass spectrometer: 5973N manufactured by Agilent Technologies, Inc.). The above liner base papers to be analyzed were peeled off from the medium base paper by the following Steps F1 to F2, and the liner base papers were dried and then pulverized by a pulverizer. Two samples of 200 to 300 [pg] of the pulverized product were analyzed using the pyrolysis gas chromatograph mass spectrometer. !s [0135] In the above pyrolysis gas chromatograph mass spectrometer, a peak was extracted with reference to a peak of the target chemical agent obtained when a calibration curve was prepared, the peak area was read, and the read peak area was compared against the above calibration curve, whereby the content concentration of the target chemical agent was calculated. The measurement was performed twice for each sample, and the average value was determined to be used as the content concentration of the chemical agent (the ratio relative to the pulp weight). It is to be noted that each chemical agent was impregnated into filter papers (manufactured of ADVANTEC, CO., LTD., circular qualitative filter paper, No. 2), so that the contents of the chemical agent were 0.01 [%], 0.1 [%], 1 [%], 5 [%], and 10 [%] by weight and then dried, which were used as samples for a calibration curve. Each sample for a calibration curve was milled, and 200 to 300 [pg] of the milled product were analyzed by the pyrolysis gas chromatograph mass spectrometer to generate the above calibration curve.

[0136]

In the above-mentioned product numbers "No. 5" and "No. 12" to "No. 15", the density was changed by adjusting the nip pressure of the multilayer paper machine. In the above product numbers "No. 6" to "No. 11", "No. 14", and "No. 15", the amount of fine fibers and the length mean fiber length were adjusted using a fiber classifier (MAX-F700, manufactured by AIKAWA Iron Works Co., Ltd.).

[0137] In each of Examples C1 to C11 and Comparative Examples C12 to C19, one medium base paper of the following product numbers "No. 16" and "No. 17" was used for the medium.

[0 - No. 16: Basis weight 120 [g/m 2 ], density 0.65 [g/cm 3] [ODN-EM120: manufactured by Oji Materia Co., Ltd.] - No. 17: Basis weight 160 [g/m 2 ], density 0.65 [g/cm 3] [ODN-EM160: manufactured by Oji Materia Co., Ltd.] For each of Examples C1 to C11 and Comparative Examples C12 to C19 above,

[5 the liner fiber information listed in Tables 8 to 10 was measured. The measured values of various parameters such as the density, the length mean fiber length, the fine fibers, the basis weight may have measurement errors of plus or minus 10%.

[0138]

[Table 8] Examples Cl C2 C3 C4 C5 C6 A A A A A E Product No. - No. 1 No. 2 No. 3 No. 4 No. 5 No. 2 Liner weight/ensit [g/m2]/[g/cm 120/0.8 170/0.8 210/0.8 280/0.8 170/0.7 170/0.8 ] 0 0 0 0 0 0 y Product No. - - - - - - Medium Basis (1) weight/densit [g/m2]/[g/cm 3] y Product No. - No. 16 No. 17 No. 17 No. 17 No. 17 No. 17 Middle Basis liner weight/densit [g/m2]/[g/cm 120/0.6 160/0.6 160/0.6 160/0.6 160/0.6 160/0.6 y 3] 5 5 5 5 5 5 y Product No. - - - - - - Medium Basis (2) weight/densit [g/m2]/[g/cm y 3]

Product No. - No. 1 No. 2 No. 3 No. 4 No. 5 No. 2 Line weigh ensit [g/m2]/[g/cm 120/0.8 170/0.8 210/0.8 280/0.8 170/0.7 170/0.8 ] 0 0 0 0 0 0 y Runkel ratio - 1.3 1.3 1.3 1.3 1.3 1.3

Liner fiber Len egthn [mm] 1.00 1.00 1.00 1.00 1.00 1.00

Amounof [%] 36.7 36.7 36.7 36.7 36.7 36.7

Total thickness [mm] 5.0 5.0 5.0 5.0 5.0 1.5 Texture A A A A A A Crease crack property B B B B B B

[0139]

[Table 9] Comp. Examples Exampl es C7 C8 C9 C1O C1l C12 AB A A A A A Product No. - No. 2 No. 6 No. 7 No. 8 No. 9 No. 10 Liner Basis [g/m2]/[g/cm 170/0.8 170/0.8 170/0.8 170/0.8 170/0.8 170/0.8 weight/densit [g 0 0 0 0 0 0 y Product No. - No. 17 - - - - Medium Basis (1) weight/densit [g/m 2 ]/[g/cm 160/0.6

Product No. - No. 17 No. 17 No. 17 No. 17 No. 17 No. 17 Middle Basis liner weight/densit [g/m2]/[g/cm 160/0.6 160/0.6 160/0.6 160/0.6 160/0.6 160/0.6 y 3] 5 5 5 5 5 5 y Product No. - No. 17 - - - - Medium Basis (2) weight/densit [g/m2][g/cm 160/0.6 y 3 Product No. - No. 2 No. 6 No. 7 No. 8 No. 9 No. 10 Liner Basis [g/m2]/[g/cm 170/0.8 170/0.8 170/0.8 170/0.8 170/0.8 170/0.8 3] 0 0 0 0 0 0 y Runkel ratio - 1.3 1.3 1.3 1.3 1.4 1.3

Liner fiber Lengthn [mm] 1.00 1.20 1.15 1.10 1.50 1.22

Amounof [%] 36.7 16.5 19.8 26.8 36.7 13.9

Total thickness [mm] 8.2 5.0 5.0 5.0 5.0 5.0 Texture A B B B B D Crease crack property B B A A A C

[0140]

[Table 10] Comparative Examples C13 C14 C15 C16 C17 C18 C19 A E AB A A A A Product No. - No. 11 No. 11 No. 11 No. 12 No. 13 No. 14 No. 15 2 Liner Basis [g/m ]/[g/cm 170/0.8 170/0.8 170/0.8 170/0.5 170/0.9 170/0.5 170/0.9 weight/densit [ ] 0 0 0 0 0 0 0

Product No. - - - No. 17 - - - Medium Basis 60/0.6 (1) weight/densit [g/m2 ]/[g/cm 1

Product No. - No. 17 No. 17 No. 17 No. 17 No. 17 No. 17 No. 17 Middle Basis liner weight/densit [g/m2 ]/[g/cm 160/0.6 160/0.6 160/0.6 160/0.6 160/0.6 160/0.6 160/0.6 3] 5 5 5 5 5 5 5

Product No. - - - No. 17 - - - Medium Basis 60/0.6 (2) weight/densit [g/m2 ]/[g/cm 1

Product No. - No. 11 No. 11 No. 11 No. 12 No. 13 No. 14 No. 15 2 Liner Basis [g/m ]/[g/cm 170/0.9 170/0.5 170/0.9 weight/densit 3] 170/0.8 170/0.8 170/0.8 170/0.5 0 0 0 y Runkel ratio - 1.3 1.3 1.3 1.3 1.3 1.3 1.4

Liner fi fber engthn [mm] 0.97 0.97 0.97 1.00 1.00 1.22 1.60

Amounof [%] 40.1 40.1 40.1 36.7 36.7 13.9 40.1

Total thickness [mm] 5.0 1.5 5.0 5.0 5.0 5.0 5.0 Texture A A A A A D B Crease crack property C C C C C D D

[0141] The "liner fiber information" is information measured on pulp fibers constituting a liner base paper, and includes three types of information: "Runkel ratio", "length mean fiber length", and "amount of fine fibers". The Runkel ratio is a parameter indicating the shape of pulp fibers, and is calculated as (Runkel ratio) = (fiber wall thickness x 2) / (fiber pore diameter). A larger Runkel ratio indicates fibers with higher rigidity. The length mean fiber length is the average of the lengths of pulp fibers constituting a liner (fiber lengths). The amount of fine fibers is the proportion [%] of the amount of contained fine fibers relative to the total pulp fibers (taken to be 100 [%]) constituting a liner. The fine fibers are fine fibers having fiber lengths of 0.0 [mm] or more and 0.2 [mm] or less.

[0142] The three types of "liner fiber information" of "Runkel ratio", "length mean fiber length", and "amount of fine fibers" were measured in the following Steps F1 to F5. Step Fl: Cut the corrugated cardboard material of the second uppermost into a 40

[cm] square, and use the 40 [cm] square corrugated cardboard sheet for measurement. The cut position was at the middle in the corrugated cardboard sheet width. Then, immerse the corrugated cardboard sheet in ion-exchanged water for 15 minutes and remove it from the ion-exchanged water. Step F2: Separate each liner base paper (the top liner and the bottom liner) of the corrugated cardboard sheet removed in Step F1 from the medium base paper by manually separating the liner base papers so as not to break the liner base papers. Step F3: Immerse each of the liner base papers and the medium base paper separated in Step F2 in ion-exchanged water for 24 hours with the adjusted concentration of 2%. Step F4: After immersing each of the liner base papers and the medium base paper

[0 with the adjusted concentration in Step F3 for 24 hours, perform dissociation by using a standard type disintegrator (manufactured by KUMAGAI RIKI KOGYO Co., Ltd.) for 20 minutes to decompose the pulp into a fibrous form. Step F5: Separate the slurry (pulp fiber) after the dissociation in Step F4, and measure the "Runkel ratio", the "length mean fiber length", and the "amount of fine

[5 fibers" by using the following fiber length measurement device. - Fiber length measurement device: Product number FS-5 UHD base unit, manufactured by Valmet

[0143] --Evaluation- !o The crease crack property and the texture were evaluated on Examples C1 to C11 and Comparative Examples C12 to C19 in which the "Runkel ratio", the "length mean fiber length", and the "amount of fine fibers" had been measured as described above. The "crease crack property" is an evaluation criterion that corresponds to !s resistance to ripping at the portions of the creases when continuous sheets of a measurement corrugated cardboard material are folded back. The "texture" is an evaluation criterion that corresponds to the uniformity of the distribution of pulp fibers constituting a liner forming a measurement corrugated cardboard material. A poor texture indicates uneven distribution of the fibers, and tends to result in uneven distribution of the strength of the liner and susceptibility to crease cracks.

[0144] The crease crack property was evaluated in a load test according to the following Steps G1 to G3. - Step G1: After gently place the measurement corrugated cardboard material on a pallet and package it with a stretch film, allow it to stand for 24 [hours] under the following temperature and humidity condition > Temperature and humidity condition: Temperature 10 [°C], humidity 10 [%Rh] - Step G2: After Step G1, apply impact to the measurement corrugated cardboard material under the following conditions using the following vibrator > Vibrator: Product name "Multiple-axle vibration testing machine", product number "DS-3000-15L", manufactured by IMV Corporation

> Excitation force: 30 [kN] > Excitation method: random wave, > Frequency: 100 [Hz] - Step G3: Visually check whether or not a crease crack occurred at the creases after the above Steps G1 and G2.

[0145] The above crease crack property was evaluated according to the following criteria. - A: There was no crease crack at all in any of the creases after Step G2.

[0 - B: A crease crack occurred at one or more creases after Step G2. - C: A crease crack occurred at one or more creases after Step G1. - D: A crease crack occurred at one or more creases before Step G1 (when being folded zigzag). Of the above criteria, "B" or more was regarded as a good evaluation and "C" or

[5 less was regarded as a poor evaluation.

[0146] In the evaluation of the "texture", the distribution of pulp fibers constituting the liner forming the measurement corrugated cardboard material was visually checked. The texture was evaluated according to the following criteria. !o - A: There was no unevenness in the pulp fibers. - B: There was unevenness in the pulp fibers (cloud-like texture). - D: Aggregates of the pulp fibers were observed. Of the above criteria, "B" or more was regarded as a good evaluation and "D" or less was regarded as a poor evaluation. !s [0147] In Examples C1 to C11, the density was 0.60 [g/cm 3] or more and 0.85 [g/cm 3 or less, the length mean fiber length was 0.98 [mm] or more and 1.55 [mm] or less, the amount of fine fibers was 15 [%] or more and 38 [%] or less, and both of the crease crack property and the texture were evaluated to be "B" or more.

[0148] In Examples C9 to C11 in which the density was 0.80 [g/cm 3] or more, the length mean fiber length was 1.10 [mm] or more, and the amount of fine fibers was 18

[%] or more, the crease crack property was evaluated to be "A". In Examples C1 to C7 in which the length mean fiber length was 0.98 [mm] or more and 1.05 [mm] or less, the texture was evaluated to be "A".

[0149] In contrast, in Comparative Examples C12 to C19 in which the density was less than 0.60 [g/cm 3] or was more than 0.85 [g/cm 3 ], the length mean fiber length was less than 0.98 [mm] or was more than 1.55 [mm], or the amount of fine fibers was less than 15 [%] or was more than 38 [%], at least the crease crack property was evaluated to be "C" or less.

[0150]

In view of Comparative Examples C12 to C19, it can be said from Examples C1 to C11 that crease cracks are suppressed at the portions of the creases of the measurement corrugated board material when the density is 0.60 [g/cm 3 ] or more and 0.85 [g/cm3 ] or less, the length mean fiber length is 0.98 [mm] or more and 1.55 [mm] or less, and the amount of fine fibers is 15 [%] or more and 38 [%] or less. It can be said from Examples C9 to C11 that crease cracks can be prevented at the portions of the creases when any one of the following is satisfied: the density is 0.80

[g/cm3] or more, the length mean fiber length is 1.10 [mm] or more, and the amount of fine fibers is 18 [%] or more.

[0 It can be said from Examples C1 to C7 that the texture is improved when the length mean fiber length is 0.99 [mm] or more and 1.00 [mm] or less.

[0151] It is inferred From Comparative Examples C17 and C19 that spaces between the pulp fibers are eliminated and the stress becomes difficult to escape when the liner

[5 is bent, so that the crease cracks are more likely to occur if the density is more than 0.90 [g/cm3 ]. It is inferred in Comparative Example 19 that the liner becomes too rigid, resulting in the further inferior evaluation of the crease crack property when the length mean fiber length is more than 1.55 [mm]. It is inferred from Comparative Examples C16 and C18 that a lot of spaces are !o generated between pulp fibers and the strength of the liner becomes insufficient, so that the crease cracks are more likely to occur when the density is less than 0.50 [g/cm 3].

[0152] It is inferred from Comparative Examples C13 to C15 that the strength of the liner becomes insufficient due to a smaller length mean fiber length and a decrease in !s the ratio of the long fibers and reduced entanglement of the pulp fibers, so that the crease cracks are more likely to occur when the length mean fiber length is less than 0.98 [mm] and the amount of fine fibers is more than 38 [%]. Further, it is inferred in Comparative Examples C13 to C15 that the difference between the short fibers and the long fibers is not conspicuous and the texture is improved when the length mean fiber length is less than 0.98 [mm] and the amount of fine fibers is more than 38 [%]. It is inferred in Comparative Example C19 that the difference between the short fibers and the long fibers becomes clearly distinctive and the texture becomes slightly inferior when the amount of fine fibers is more than 38 [%] but the length mean fiber length is more than 1.55 [mm]. It is inferred from Comparative Example C12 that the proportion of pulp fibers having greater fiber lengths (long fibers) increases and spaces between long fibers increases, so that the crease cracks are more likely to occur when the amount of fine fibers is less than 15[%].

[0153]

[III. Modification] The embodiment described above is merely an example, and there is no intention to exclude the application of various modifications and techniques not specified in the embodiment. Each configuration of the present embodiment can be variously modified without departing from the gist thereof. The configurations can be selected as necessary or can be combined as appropriate.

[0154] For example, the corrugated cardboard material is not limited to the corrugated cardboard material 1 folded zigzag, and may be corrugated cardboard sheets separated from one another. As the corrugated cardboard material, a single-faced corrugated cardboard having a liner on one side of a medium may be used. The apparatus for folding corrugated cardboards zigzag is not particularly limited. Irrespective of the

[0 structure of a folding apparatus, corrugated cardboard materials that are folded zigzag by a folding apparatus may have the above-described problems I to IV. When the corrugated cardboard material is used in a box-making system, the creases preferably omit additional processing such as intentionally formed slits or perforations, and preferably locate at portions where the corrugated cardboard material

[5 is folded back by 180 [0] at creased lines provided on the surface layer of the liner (e.g., such that the creased lines come to the inside). On the other hand, when the corrugated cardboard material is used for applications other than the box-making system, the creases may involve processing such as slits and perforations.

[0155] !o The use of the corrugated cardboard material folded zigzag described above should not be limited to the use as a material for making boxes applied in a box-making system. The corrugated cardboard material folded zigzag can be utilized in various ways by effectively using the structure of the multiple sheets connected via the creases, !s which is different from the structure of the conventional corrugated cardboard sheets separated from one another. For example, the corrugated cardboard material folded zigzag can be used as a web-shaped paper material having a large dimension along the extending direction when the sheets are unfolded.

[0156] The ways to utilize the web-shaped paper material can be exemplified by the following uses. Use as a disaster product: When attached to a window, it can be used to prevent window cracks against a typhoon. In addition, it can be used as a partition for privacy protection and stress reduction in evacuation shelters, or as a cushion or a rug for countering cold. Use at entertainment events: It can be used for creations such as signboards in entertainments or school events. Use as an architecture/a material for moving: It can be utilized as a protection (preserving material) of a type to be attached to an object when doors, walls, gates, etc. need to be protected at construction sites or moving sites. It can be used also as a protection (packing material) of a type to be wrapped around the object.

In any of the utilizing ways, according to the structure of the multiple sheets connected via the creases, there are advantages that operation efficiency can be enhanced and the dimension in the extending direction can be secured.

[IV. Appendixes] Appendices relating to the above embodiments are disclosed.

[Appendix 1] A corrugated cardboard material comprising a cardboard comprising a liner attached to a medium, characterized in that a dynamic viscoelasticity measured on a measurement piece cut out from the

[0 liner in a tensile shear mode of a vibration condition of a frequency of 100 [Hz] under a temperature condition of 25 [°C] is within a predetermined range, the dynamic viscoelasticity is defined by a value of an elastic modulus E' and a value of tan6 which is a ratio of a loss elastic modulus E" to the elastic modulus E', the predetermined range comprises:

[5 the elastic modulus E'of 1.00 x 109 [Mpa] or more and 8.00 x 109 [Mpa] or less, and the tan6 of 2.50 x 10-2 or more and 1.50 x 10-1 or less.

[Appendix 2] The corrugated cardboard material according to Appendix 1, characterized in !o that the elastic modulus E' is 3.00 x 109 [Mpa] or less, and the tan6 is 7.00 x 10-2 or more.

[Appendix 3] The corrugated cardboard material according to Appendix 1, characterized in !s that the elastic modulus E' is 4.00 x 109 [Mpa] or more, and the tan6 is 4.00 x 10-2 or less.

[Appendix 4] The corrugated cardboard material according to any one of Appendixes 1 to 3, characterized in that a freeness of a pulp used for the base paper forming the liner is 350 [ml] or more and 500 [ml] or less.

[Appendix 5] The corrugated cardboard material according to any one of Appendixes 1 to 4, characterized in that a double-faced corrugated cardboard in which the liner is bonded to both sides of the medium is used as the corrugated cardboard.

[Appendix 6] The corrugated cardboard material according to any one of Appendixes 1 to 5, characterized in that the corrugated cardboards which are continuous in a band shape are alternately folded back and stacked one another so as to be folded zigzag.

[Appendix 7] A corrugated cardboard material comprising a cardboard comprising a liner attached to a medium, the corrugated cardboards which are continuous in a band shape being alternately folded back and stacked one another so as to be folded zigzag, characterized in that a dynamic viscoelasticity measured on a measurement piece cut out from the liner in a tensile shear mode of a vibration condition of a frequency of 100 [Hz] under a temperature condition of 25 [°C] is within a predetermined range, the dynamic viscoelasticity is defined by a value of an elastic modulus E' and a

[0 value of tan6 which is a ratio of a loss elastic modulus E" to the elastic modulus E', the predetermined range comprises: the elastic modulus E'of 1.00 x 109 [Mpa] or more and 3.00 x 109 [Mpa] or less, and the tan6 of 7.00 x 10-2 or more and 1.50 x 10-1 or less.

[5 [Appendix 8] The corrugated cardboard material according to Appendix 7, characterized in that a freeness of a pulp used for the base paper forming the liner is 350 [ml] or more and 500 [ml] or less. !o [Appendix 9] The corrugated cardboard material according to Appendix 7 or 8, characterized in that a double-faced corrugated cardboard in which the liner is bonded to both sides of the medium is used as the corrugated cardboard. !s [Appendix 10] A corrugated cardboard material comprising a cardboard comprising a liner attached to a medium, characterized in that an amount of a sizing agent added to the liner is 0.2 [parts by mass] or more and 4.0 [parts by mass] or less, an amount of a paper strength agent added to the liner is 0.1 [parts by mass] or more and 4.0 [parts by mass] or less, a length mean fiber length of pulp fibers constituting the liner is 0.90 [mm] or more and 1.55 [mm] or less, and an amount of fine fibers having a fiber length of 0.0 [mm] or more and 0.2 [mm] or less included in the pulp fibers constituting the liner is 23 [%] or more and 48 [%] or less.

[Appendix 11] The corrugated cardboard material according to Appendix 10, characterized in that the amount of the sizing agent added is 0.8 [parts by mass] or more.

[Appendix 12]

The corrugated cardboard material according to Appendix 10 or 11, characterized in that the amount of the paper strength agent added is 1.0 [parts by mass] or more.

[Appendix 13] The corrugated cardboard material according to any one of Appendixes 10 to 12, characterized in that the length mean fiber length is 1.50 [mm] or more.

[Appendix 14] The corrugated cardboard material according to any one of Appendixes 10 to 13,

[0 characterized in that the amount of fine fibers included is 40 [%] or more.

[Appendix 15] The corrugated cardboard material according to any one of Appendixes 10 to 14, characterized in that 1s a double-faced corrugated cardboard in which the liner is bonded to both sides of the medium is used as the corrugated cardboard.

[Appendix 16] The corrugated cardboard material according to any one of Appendixes 10 to 15, characterized in that !o the corrugated cardboards which are continuous in a band shape are alternately folded back and stacked one another so as to be folded zigzag.

[Appendix 17] A corrugated cardboard material comprising a cardboard comprising a liner attached to a medium, characterized in that !s a density of the liner is 0.60 [g/cm 3] or more and 0.85 [g/cm 3 ] or less; a length mean fiber length of pulp fibers constituting the liner is 0.98 [mm] or more and 1.55 [mm] or less, and an amount of fine fibers having a fiber length of 0.0 [mm] or more and 0.2 [mm] or less included in the pulp fibers constituting the liner is 15 [%] or more and 38 [%] or less.

[Appendix 18] The corrugated cardboard material according to Appendix 17, characterized in that the density is 0.80 [g/cm 3] or more, the length mean fiber length is 1.10 [mm] or more, and the amount of fine fibers included is 18 [%] or more.

[Appendix 19] The corrugated cardboard material according to Appendix 17, characterized in that the length mean fiber length is 0.98 [mm] or more and 1.05 [mm] or less.

[Appendix 20]

The corrugated cardboard material according to any one of Appendixes 17 to 19, characterized in that a double-faced corrugated cardboard in which the liner is bonded to both sides of the medium is used as the corrugated cardboard.

[Appendix 21] The corrugated cardboard material according to any one of Appendixes 17 to 20, characterized in that the corrugated cardboards which are continuous in a band shape are alternately folded back and stacked one another so as to be folded zigzag.

[0 Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to".

[5

DESCRIPTION OF REFERENCE SIGNS

[0157] 1 corrugated cardboard material 10 flute shape (corrugating shape) !o 2 sheet 20 sheet pair 21 first sheet 22 second sheet 23 third sheet !s 50 folding apparatus 50A conveyance part 50B folding part 50C stacking part F crease L auxiliary line L1 longitudinal dimension (first dimension) L2 lateral dimension (second dimension) L3 height dimension (third dimension)

Claims (5)

CLAIMS What is claimed is:

1. A corrugated cardboard material comprising a cardboard comprising a liner attached to a medium, characterized in that a density of the liner is 0.60 [g/cm 3] or more and 0.85 [g/cm 3] or less; a length mean fiber length of pulp fibers constituting the liner is 0.98 [mm] or

[0 more and 1.55 [mm] or less, and an amount of fine fibers having a fiber length of 0.0 [mm] or more and 0.2 [mm] or less included in the pulp fibers constituting the liner is 15 [%] or more and 38 [%] or less.

2. The corrugated cardboard material according to claim 1, characterized in that

[5 the density is 0.80 [g/cm 3] or more, the length mean fiber length is 1.10 [mm] or more, and the amount of fine fibers included is 18 [%] or more.

3. The corrugated cardboard material according to claim 1, characterized in that !o the length mean fiber length is 0.98 [mm] or more and 1.05 [mm] or less.

4. The corrugated cardboard material according to any one of claims 1 to 3, characterized in that a double-faced corrugated cardboard in which the liner is bonded to both sides !s of the medium is used as the corrugated cardboard.

5. The corrugated cardboard material according to any one of claims 1 to 4, characterized in that the corrugated cardboards which are continuous in a band shape are alternately folded back and stacked one another so as to be folded zigzag.