JP2022118526A - Corrugated cardboard material and corrugated cardboard box using the same - Google Patents

Abstract

To ensure both the strength of a manufactured box and the ease of crushing of it.SOLUTION: A corrugated cardboard material 1 of the invention is obtained by folding continuous double-sided corrugated cardboard into a bellows fold at a fold F. The liner constituting the double-sided corrugated cardboard has a basis weight of 80 [g/m2] or more and 270 [g/m2] or less, a length-weighted average fiber length of 0.90 [mm] or more and 1.50 [mm] or less, a Runkel ratio of 1.20 or more and 1.60 or less, and an added amount of a paper force enhancer of 0.15 [part by mass] or more and 5.25 [parts by mass] or less. The center core constituting the double-sided corrugated cardboard has a basis weight of 80 [g/m2] or more and 180 [g/m2] or less, a length-weighted average fiber length of 0.86 [mm] or more and 1.24 [mm] or less, a Runkel ratio of 0.96 or more and 1.29 or less, and an addition amount of the paper force enhancer of 0.01 [part by mass] or more and 3.90 [parts by mass] or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a bellows-folded cardboard material and a cardboard box using the same.

Accordion-folded corrugated cardboard (also called “fanfold”) is known as a box-making material. The corrugated cardboard material is provided with creases between continuous rectangular sheets, and the sheets are alternately folded back at the creases. In such a bellows-folded corrugated cardboard material, continuous sheets are vertically stacked and folded into a rectangular parallelepiped packing form.

The above corrugated cardboard can be manufactured using a box-making system ("automatic packaging system", "three-sided variable system", "three-sided automatic packing", "on-demand packaging") that manufactures boxes of the optimum size according to the size of the packaging target. ” etc.) is used for packaging materials. In this box-making system, various processes exemplified below are performed.
・Feeding process: The process of feeding corrugated cardboard material ・Cut process: The process of cutting out flat cardboard material fed out in the feeding process ・Folding process: The process of assembling boxes from the cardboard material cut out in the cutting process

Japanese Patent Publication No. 2013-513869

However, when bellows-folded corrugated cardboard is used as a material for a box-making system, the strength of the manufactured box may be insufficient depending on the properties of the sheet used for the corrugated cardboard. Also, if the strength of the manufactured box is too high, it may become difficult to crush. In addition, voids and lateral deviation of the sheet may occur near the crease of the corrugated cardboard material folded in accordion-folding, resulting in insufficient accordion-folding performance.
The present invention was invented in view of the above problems, and one of the objects is to ensure the strength, easiness of crushing, and bellows foldability of the manufactured box. In addition to this purpose, it is also possible to achieve actions and effects that are derived from each configuration shown in the "Mode for Carrying Out the Invention" described later and that cannot be obtained with conventional techniques. It can be positioned as another purpose.

The corrugated cardboard material disclosed herein is a continuous double-faced corrugated cardboard in which a rectangular sheet extends linearly along the first direction at each fold, and the plane along the fold is perpendicular to the first direction. It is a bellows-folded corrugated cardboard material in which the sheets are folded in two directions and stacked along a third direction orthogonal to both the first direction and the second direction.
In the present corrugated cardboard material, the basis weight of the liner constituting the double-sided corrugated cardboard is 80 [g/m ² ] or more and 270 [g/m ² ] or less, and the weighted average fiber length of the pulp fibers of the liner is 0.90 [mm] or more and 1.50 [mm] or less, the Runkel ratio of the pulp fibers of the liner is 1.20 or more and 1.60 or less, and is added to the liner The added amount of the paper strength agent is 0.15 [parts by mass] or more and 5.25 [parts by mass] or less.
Moreover, in the present corrugated cardboard material, the basis weight of the core constituting the double-sided corrugated cardboard is 80 [g/m ² ] or more and 180 [g/m ² ] or less, and the length-weighted average fiber of the core is The length is 0.86 [mm] or more and 1.24 [mm] or less, the Runkel ratio of the core is 0.96 or more and 1.29 or less, and the paper strength enhancement of the core The amount of the agent added is 0.01 [parts by mass] or more and 3.90 [parts by mass] or less.

According to the present invention, it is possible to ensure the strength, easiness of crushing, and bellows foldability of a box manufactured from a corrugated cardboard material.

FIG. 2 is a perspective view showing a corrugated cardboard material folded in accordion.

A cardboard material and a cardboard box as embodiments will be described below.
The corrugated cardboard material of the present embodiment is a bellows-folded box-making material in which a rectangular sheet is folded in a continuous corrugated board. Double-faced corrugated cardboard having liners on both sides of the core is used as the corrugated cardboard material.

The above-mentioned double-faced corrugated cardboard includes single-flute corrugated cardboard composed of three base papers (materials) corresponding to one core and two liners, as well as so-called "double-faced corrugated cardboard" and "double-faced corrugated cardboard". Also included are multi-flute corrugated cardboards composed of three or more cores (including one or more inner liners) and five or more base papers corresponding to each of the two liners. In this embodiment, a corrugated cardboard material consisting of a single-flute double-faced corrugated board is mainly exemplified.

When the cardboard material is made into a carton, it becomes a carton box. Specifically, the corrugated cardboard materials used for the box-making materials of the box-making system are divided into a feed process in which the sheets are fed out in order, a cutting process in which the fed-out sheets are cut out in a developed pattern of the box, and a folding process in which the sheets are folded into the box shape. It is made into a cardboard box through various processes such as folding process to stand up. The box making system for assembling cardboard boxes is not particularly limited, but for example, "Carton Wrap 1000 manufactured by CMC" and "CVP-500 manufactured by Neopost" which are fully automatic systems (fully automatic machines) of automatic packaging systems. , "TXP-600 manufactured by OS Machinery", "EM7 manufactured by Pack Size", "Compack manufactured by Panotec", "Made by HOMAG", a semi-automatic system (semi-automatic machine) that performs from the feeding process to the cutting process PAQTEQ C-200" and "PAQTEQ C-250 manufactured by HOMAG" can be used.

In this embodiment, it is assumed that the following directions I and II correspond to each other as shown in Table 1 below, and the corrugated board is placed on a horizontal plane.
・Direction I: Direction in the corrugated board placed on the horizontal plane ・Direction II: Direction in the semi-finished product in the middle of manufacturing the corrugated board

The longitudinal direction (first direction, indicated as "CD" in the figure) and the transverse direction (second direction, indicated as "MD" in the figure) are horizontal directions along the sheet (fold). It is the direction in which the plane extends. These vertical and horizontal directions are orthogonal to each other. The height direction (third direction, indicated as "TD" in the drawing) is a direction along the vertical direction and orthogonal to both the vertical direction and the horizontal direction. This height direction corresponds to the direction in which the sheets are superimposed.

The MD (Machine Direction) direction is also referred to as the "flow direction", and is the direction in which the manufacturing process of corrugated cardboard and the process of a box making system using corrugated cardboard as materials progress from upstream to downstream. A CD (Cross Direction) direction is a direction orthogonal to the MD direction on a plane along the MD direction. A TD (Transverse Direction) direction is a direction orthogonal to both the MD direction and the CD direction.
In addition, unless otherwise specified, the expression "numerical value X to numerical value Y" in the present embodiment means a range from numerical value X or more to numerical value Y or less.

[I. one embodiment]
In one embodiment below, the configuration of the cardboard material is described in items [1] and [2]. In item [1], a structure in which the cardboard material is folded (hereinafter referred to as "folded structure") will be described. In item [2], the parameters relating to the corrugated board are explained.
The action and effect of the configurations of items [1] and [2] will be described in item [3].

[1. Folding structure]
As shown in FIG. 1, the corrugated cardboard 1 is a box-making material having a rectangular parallelepiped shape.
In the cardboard material 1, a continuous rectangular sheet 2 (only a part of which is labeled in FIG. 1) is folded back at a fold line F (only a part of which is labeled in FIG. 1), and the folded sheet 2 is Stacked vertically.
In the corrugated cardboard material 1 folded in this way, a plurality of folds F are linearly extended in the longitudinal direction on a pair of side surfaces along both the longitudinal direction and the height direction.

Here, the folding structure of the corrugated cardboard material 1 will be described by focusing on three continuous sheets 2 (indicated by two-dot chain lines in FIG. 1).
- First sheet 21: sheet 2 continuous to one side of second sheet 22
- Second sheet 22: Sheet 2 that is continuous with both the first sheet 21 and the third sheet 23
- Third sheet 23: sheet 2 continuous to the other side of second sheet 22

A first fold F1 is provided between the first sheet 21 and the second sheet 22, and the sheets 21 and 22 are continuous via the first fold F1. A second fold F2 is provided between the second sheet 22 and the third sheet 23, and the sheets 22 and 23 are continuous via the second fold F2.
The first fold line F1 is a fold line F where the second sheet 22 is folded back toward one side of the first sheet 21 (toward the right in FIG. 1), and the other side of the corrugated board 1 ( left side in FIG. 1). The second fold line F2 is a fold line F where the third sheet 23 is folded back toward the other side of the second sheet 22 (to the left in FIG. 1), and the one side of the corrugated cardboard 1 in the horizontal direction ( (right side in FIG. 1).

In the first sheet 21, corrugated cardboard corrugations ₁₀ ( waves) are exposed. Similarly, the second sheet 22 has a second edge E ₂ (only the edge on the front side is labeled in FIG. 1) extending in the lateral direction (the direction intersecting with the fold line F). Step 10 is exposed.
In the sheet pair 20 composed of the first sheet 21 and the second sheet 22, the _first edge E1 and the _second edge E2 are arranged adjacent to each other in the height direction.

According to the corrugated cardboard material 1 having the folding structure described above, even materials that are difficult to roll into a roll can be folded into a rectangular parallelepiped shape. That is, the corrugated cardboard sheet 2, which has a higher strength than the material that can be wound into a roll, can be compactly packed. The corrugated cardboard 1 in which the sheet 2 whose strength is ensured is folded in this manner is suitable for use as a packaging material for a box manufacturing system for manufacturing boxes that require strength.

In addition, the folds F are provided along corrugations 10 of the corrugated cardboard. In other words, the corrugated board 1 with the steps 10 perpendicular to the MD direction is manufactured.
The cardboard material 1 is preferably wrapped (packaged) with a packaging film in order to prevent contamination and collapse of cargo.

[2. parameter]
The parameters of the corrugated board 1 are described below.
First, basic parameters such as the size and the number of layers of the cardboard material 1 will be described. After that, the parameters related to the properties of the corrugated board 1 will be described in detail.

[2-1. basic parameters]
The size of the cardboard material 1 is determined from the following dimensions L1 to L3.
・ Vertical dimension L1: Vertical dimension (first dimension)
・ Lateral dimension L2: Lateral dimension (second dimension)
・Height dimension L3: Dimension in height direction (third dimension)
The smaller the dimensions L1 to L3, the greater the restrictions on the size and shape of the box to be manufactured. From these points of view, the dimensions L1 to L3 are preferably within the ranges shown in Table 2 below.

In addition, if the number of folds F in the cardboard material 1 is N, the number of sheets 2 is N+1. In this case, N+1 [stages] of sheets 2 are stacked on the corrugated board 1 .
For example, the number of stages of the corrugated board 1 may be various, for example, 10 to 1000 stages. For corrugated cardboards whose folding-related parameters are to be measured, which will be described later in detail, it is preferable to measure the parameters for each of all the stages of the object with less than a predetermined number of stages (for example, 100 [stages]). On the other hand, for a measurement target with a predetermined number of stages (eg, 100 [stages]) or more, parameters may be measured partially (eg, divided into parts or set regions).

It should be noted that the sheet 2 used for the corrugated cardboard 1 can be set to an arbitrary basis weight. The basis weight range for the sheet 2 is 50 to 1500 [g/m ² ], preferably 100 to 1000 [g/m ² ], more preferably 200 to 1000 [g/m 2 ]. 800 [g/m ² ], more preferably 200 to 600 [g/m ² ].
The weight of the corrugated cardboard 1 is calculated by adding the corrugation rate of the core to the basis weight and multiplying the vertical dimension L1 and the horizontal dimension L2 by the number of corrugations N+1 of the sheet 2 .

[2-2. Parameters related to properties]
The corrugated cardboard 1 of the present embodiment has a predetermined configuration regarding properties based on the following viewpoints.
- Aspect: Ensuring the strength, easiness of crushing, and bellows folding of the manufactured box.
・Problem 1: The strength of the manufactured box is insufficient. ・Problem 2: The manufactured box is difficult to crush.

Predetermined configurations corresponding to the above viewpoints and problems 1, 2, and 3 include configurations described below.
・Configuration: Configuration 1 and Configuration 2 below
> Configuration 1: The liner has the following configurations 1A to 1D
Configuration 1A: The basis weight is within a predetermined first basis weight range
Configuration 1B: Length of fiber length Weighted average fiber length is in a predetermined first length range
Configuration 1C: The Runkel ratio is within a predetermined first ratio range
Configuration 1D: The addition amount of the paper strength agent is within the predetermined first addition amount range> Configuration 2: The core has the following configurations 2A to 2D
Configuration 2A: The basis weight is within a predetermined second basis weight range
Configuration 2B: Length of fiber length Loaded average fiber length is in the second range of predetermined length
Configuration 2C: The Runkel ratio is in a predetermined second ratio range
Configuration 2D: The addition amount of the paper strength agent is within the predetermined second addition amount range

“Basis weight” is a parameter corresponding to the weight per unit square meter [g/m ² ] of the liner and core that constitute the corrugated board 1 . As the basis weight increases, the hardness and strength of the liner and core tend to increase, and as the basis weight decreases, the hardness and strength of the liner and core tend to decrease.
“Length-loaded average fiber length” is a parameter corresponding to the average value of the length (fiber length) of pulp fibers contained in the liner and core forming the corrugated board 1 .
When the fiber length value is large, the pulp fibers tend to become entangled with each other, and the hardness of the liner and core tends to increase. When the fiber length value is small, the pulp fibers are less likely to entangle with each other, and the flexibility of the liner and core tends to increase.

The “Runkel ratio” is a parameter that indicates the shape of the pulp fibers contained in the liner and core that constitute the corrugated board 1, and (Runkel ratio)=(twice the fiber wall thickness)/(fiber lumen diameter). Calculated by
A higher Runkel ratio indicates a stiffer fiber. High values of the Runkel ratio tend to increase the stiffness of the fiber and increase the stiffness of the liner or core. Small Runkel ratio values tend to increase the softness of the pulp fibers, resulting in supple liners and cores.

The "paper strength enhancer" is a chemical added to the liner and core forming the corrugated board 1 in order to improve the surface strength and prevent the generation of paper dust during printing. The added amount [parts by mass] of the paper strength enhancer is the ratio of the added amount [parts by mass] of the paper strength enhancer to the total 100 [parts by mass] of the total pulp constituting the liner and corrugating medium. .
As the amount of the paper strength enhancer added increases, the hardness of the liner and core tends to increase. Small Runkel ratio values tend to increase the softness of the pulp fibers resulting in supple liners and cores.

A single cardboard box (hereinafter referred to as a "folded cardboard box") can be manufactured by using a continuous sheet 2 straddling the fold F from the corrugated cardboard material 1 folded in a bellows shape. Cardboard boxes with folds tend to have insufficient strength at locations including the folds F, which tends to cause problem 1.
The strength of the cardboard box manufactured using the cardboard material 1 can be ensured by increasing the hardness and strength of the liner and core constituting the cardboard material 1 . However, if the strength of the manufactured cardboard box is too high, Problem 2 may occur.

Generally, when discarding a cardboard box, it is crushed or folded to make it less bulky. In a distribution center or the like where a large number of cardboard boxes are discharged, a cardboard box crushing machine is used to automatically crush the boxes in order to save labor and time required for disposal. If the cardboard box is difficult to crush, the cardboard box cannot be crushed by the cardboard box compression crusher, and the box may become clogged in the device, causing the device to stop.

The corrugated cardboard 1 is obtained by folding a continuous sheet 2 at folds F to form a bellows fold, as shown in FIG. In the corrugated cardboard material 1, if the liner or core is insufficiently hard or too hard, gaps may occur near the folds or the sheet 2 may be displaced, leading to problem 3. be.

The inventors of the present application have found that if the liner constituting the corrugated board 1 has the above structures 1A to 1D and the core constituting the corrugated board 1 has the structures 2A to 2D, the problems 1 and 2 described above can be solved. and 3 tend to be suppressed. Conversely, corrugated cardboard materials provided with a liner or core that do not have at least one of the above structures 1A to 1D and structures 2A to 2D tend to cause problems 1, 2, or 3. I found
That is, the corrugated board 1 is provided with the configurations 1A to 1D and the configurations 2A to 2D based on the aspects 1, 2 and 3 described above.

If at least one of the grammage of the liner or core, the length-loaded average fiber length, the runkel ratio, or the added amount of the paper strength agent is below the specified range, the strength of the liner or core is insufficient. sufficient and tends to lead to problems 1 and 3 above.
If at least one of the grammage of the liner or core, the length-loaded average fiber length, the Runkel ratio, or the amount of the paper strength agent added exceeds a predetermined range, the strength of the liner or core is excessive. , which tends to lead to problems 2 and 3.

The first basis weight range of the basis weight of the liner is 80 [g/m ² ] or more and 270 [g/m ² ] or less, preferably 110 [g/m ² ] or more and 250 [g/m 2 ] or more. /m ² ] or less, more preferably 120 [g/m ² ] or more and 210 [g/m ² ] or less.
The first length range of the length-weighted average fiber length of the liner is 0.90 [mm] or more and 1.50 [mm] or less, preferably 0.92 [mm] or more. It is 45 [mm] or less, more preferably 0.95 [mm] or more and 1.40 [mm] or less.

The first ratio range of the Runkel ratio of the liner is 1.20 or more and 1.60 or less, preferably 1.22 or more and 1.55 or less, more preferably 1.25 or more. is 1.50 or less.
The first addition amount range of the paper strength agent for the liner is 0.15 [parts by mass] or more and 5.25 [parts by mass] or less, preferably 0.90 [parts by mass] or more and 4 00 [mass parts] or less, more preferably 1.25 [mass parts] or more and 3.30 [mass parts] or less.

The second basis weight range of the basis weight of the core is 80 [g/m ² ] or more and 180 [g/m ² ] or less, preferably 110 [g/m ² ] or more and 170 [g/m 2 ] or more. [g/m ² ] or less, more preferably 120 [g/m ² ] or more and 160 [g/m ² ] or less.
The second length range of the length-weighted average fiber length of the core is 0.86 [mm] or more and 1.24 [mm] or less, preferably 0.88 [mm] or more and 1 0.22 [mm] or less, more preferably 0.90 [mm] or more and 1.20 [mm] or less.

The second ratio range of the Runkel ratio of the core is 0.96 or more and 1.29 or less, preferably 0.98 or more and 1.27 or less, more preferably 1.00 or more. is 1.25 or less.
The second addition amount range of the paper strength agent for the core is 0.01 [parts by mass] or more and 3.90 [parts by mass] or less, preferably 0.05 [parts by mass] or more It is 3.80 [parts by mass] or less, more preferably 0.40 [parts by mass] or more and 3.10 [parts by mass] or less.

[3. Action and effect]
The cardboard material 1 of the present embodiment can ensure the strength, easiness of crushing, and bellows foldability of the box manufactured from the cardboard material by the configurations 1 and 2.
By providing the configurations 1 and 2 described above, it is possible to manufacture a box in good condition when the corrugated cardboard material 1 is used as a material for making boxes.

[II. Example]
EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples. However, the present invention is not limited to the following examples.
--Preprocessing--
The corrugated cardboard material or part of it, which is the object of parameter measurement, was pretreated for 24 hours or more under temperature and humidity conditions of 23 [°C] and 50 [%] humidity in accordance with JIS Z0203:2000. After that, each parameter was measured.
In addition, the usual one-tank starch paste was used as the corrugated cardboard adhesive for laminating the liner base paper and core base paper. Also, the corrugated cardboard for measurement was manufactured using a corrugator having corrugating rolls.

--Measurement target--
In Examples 1 to 22 and Comparative Examples 23 to 32, the cardboard materials to be measured had the following sizes (packaging dimensions).
・ Size: Vertical dimension 1300 [mm],
Horizontal dimension 1150 [mm],
Height dimension 1800 [mm]
In Examples 1 to 22 and Comparative Examples 23 to 32, any one of the following five types of flutes was used as the cardboard material for measurement.
・ A flute (number of stages: 360 [stages])
・ B flute (number of stages: 600 [stages])
・ AC flute (number of stages: 200 [stages])

In Examples 1 to 22 and Comparative Examples 23 to 32, corrugated cardboard materials to be measured were produced using a corrugator having corrugating rolls with the following specifications.
>A flute ・Step height: 4.5 [mm]
・Number of steps: 34 [mountain/30cm]
>B flute ・Step height: 2.5 [mm]
・Number of steps: 50 [mountain/30 cm]
>AC flute --A flute--
・ Step height: 4.5 [mm]
・Number of steps: 34 [mountain/30cm]
--C flute--
・ Step height: 3.5 [mm]
・Number of steps: 40 [mountain/30 cm]
The “number of ridges” corresponds to the number of ridges (tiers) per 30 [cm] on the sheet, and corresponds to a numerical value obtained by dividing 30 [cm] by the wavelength of the tier.

In Examples 1 to 22 and Comparative Examples 23 to 32, any one of the following liner base papers with product numbers “No.
・No. 1 to 7, No. 14 to 18: Basis weight 180 [g/m ² ]
・ No. 8, 12: Basis weight 120 [g/m ² ]
・ No. 9, 13: Basis weight 210 [g/m ² ]
・ No. 10: Basis weight 50 [g/m ² ]
・ No. 11: Basis weight 280 [g/m ² ]

The liner base paper of product number “No. A liner base paper for corrugated board composed of three layers was prepared under the following paper-making conditions. Freeness was measured by the following measuring device in accordance with JIS P8121 2012.
・Measuring device: Product name “Canadian Standard Freeness”, Kumagai Law of nature machine Industrial Co., Ltd.
company, product number "No. 2580-A"

・ Paper making conditions for product number “No. 1”> Sizing agent: Agent name “Size Pine N-830 (manufactured by Arakawa Chemical Industries, Ltd.)”
0.5 [mass
Part] > Paper strength agent: The drug name "PT-1001 (Arakawa Chemical Industries Co., Ltd.)" is added to the entire pulp of the paper layer
Contains 0.50 [parts by mass] for a total of 100 [parts by mass] > Aluminum sulfate: 5 [parts by mass] for a total of 100 [parts by mass] of all pulp in the paper layer
> NKP: Contained at a rate of 10 [mass%] > LKP: Contained at a rate of 80 [mass %] > MP: Contained at a rate of 10 [mass %]

The liner base paper of product number "No. 2" is the same as the liner base paper of "No. 1" except that NKP is changed to 5 [mass%], LKP to 85 [mass%], and MP to 10 [mass%]. created by the method of
The liner base paper of product number "No. 3" is the same as the liner base paper of "No. 1" except that NKP is changed to 20 [mass%], LKP to 70 [mass%], and MP to 10 [mass%]. created by the method of
The liner base paper of product number "No. 4" was prepared in the same manner as the liner base paper of "No. 1" except that the amount of the paper strength enhancer added was changed to 0.20 [parts by mass].
The liner base paper of product number "No. 5" was prepared in the same manner as the liner base paper of "No. 1" except that the amount of the paper strength enhancer added was changed to 1.00 [parts by mass].

The liner base paper of product number "No. 6" was prepared in the same manner as the liner base paper of "No. 1" except that the amount of the paper strength enhancer added was changed to 3.50 [mass parts].
The liner base paper of product number "No. 7" was prepared in the same manner as the liner base paper of "No. 1" except that the amount of the paper strength enhancer added was changed to 5.00 [mass parts].
The liner base paper of product number "No. 8" was prepared in the same manner as the liner base paper of "No. 1" except that the basis weight was changed to 120 [g/m ² ].
The liner base paper of product number "No. 9" was prepared in the same manner as the liner base paper of "No. 1" except that the basis weight was changed to 210 [g/ ^m2 ].
The liner base paper of product number "No. 10" was prepared in the same manner as the liner base paper of "No. 1" except that the basis weight was changed to 50 [g/m ² ].
The liner base paper of product number “No. 11” was prepared in the same manner as the liner base paper of “No. 1” except that the basis weight was changed to 280 [g/m ² ].

The liner base paper of product number “No. 12” has a basis weight of 120 [g/m ² ], NKP of 5 [mass%], LKP of 90 [mass%], and MP of 5 [mass%]. It was prepared in the same manner as the "No. 1" liner base paper, except that it was changed.
The liner base paper of product number “No. 13” has a basis weight of 210 [g/m ² ], NKP of 30 [mass%], LKP of 60 [mass%], and MP of 10 [mass%]. It was prepared in the same manner as the "No. 1" liner base paper, except that it was changed.
The liner base paper of product number “No. 14” was prepared in the same manner as the liner base paper of “No. 8” except that the basis weight was changed to 180 [g/m ² ].

The liner base paper of product number "No. 15" was prepared in the same manner as the liner base paper of "No. 1" except that the amount of the paper strength enhancer added was changed to 0.10 [parts by mass].
The liner base paper of product number "No. 16" was prepared in the same manner as the liner base paper of "No. 1" except that the amount of the paper strength enhancer added was changed to 5.50 [mass parts].
The liner base paper of product number "No. 17" was prepared in the same manner as the liner base paper of "No. 1" except that the amount of the paper strength enhancer added was changed to 1.30 [parts by mass].
The liner base paper of product number "No. 18" was prepared in the same manner as the liner base paper of "No. 1" except that the amount of the paper strength enhancer added was changed to 3.20 [mass parts].

In Examples 1 to 22 and Comparative Examples 23 to 32, any one of the following liner base papers with product numbers “No.
・No. 19-25, No. 30 to 33: Basis weight 160 [g/m ² ]
・ No. 26, 29: Basis weight 120 [g/m ² ]
・ No. 27: Basis weight 50 [g/m ² ]
・ No. 28: Basis weight 210 [g/m ² ]

The core raw paper of product number "No. 19" is a pulp slurry obtained by mixing miscellaneous waste paper with a freeness of 300 [ml] and a concentration of 3 [%] and corrugated waste paper with a freeness of 400 [ml] and a concentration of 4 [%]. was used as a raw material, paper was made using a paper machine, and core raw paper for corrugated board composed of one layer was prepared under the following paper-making conditions. Freeness was measured by the following measuring device in accordance with JIS P8121 2012.
・Measuring device: Product name “Canadian Standard Freeness”, Kumagai Law of nature machine Industrial Co., Ltd.
company, product number "No. 2580-A"

・ Papermaking conditions for product number “No. 19”> Sizing agent: Agent name “Size Pine N-830 (manufactured by Arakawa Chemical Industries, Ltd.)”
0.50 [mass
Part] > Paper strength agent: The drug name "PT-1001 (Arakawa Chemical Industries Co., Ltd.)" is added to the entire pulp of the paper layer
Contains 0.30 [parts by mass] for a total of 100 [parts by mass] > Aluminum sulfate: 1.00 [parts by mass] for a total of 100 [parts by mass] of all pulp in the paper layer
] Contains >Pulp slurry: 15 [mass%] of miscellaneous waste paper and 85 [mass%] of corrugated waste paper
with mixed pulp slurry

The core raw paper of product number “No. 20” is the pulp slurry of “No. It was made in the same way as the corrugating medium.
The core raw paper of product number “No. 21” is the pulp slurry of “No. It was made in the same way as the corrugating medium.
The corrugating medium of product number "No. 22" was prepared in the same way as the corrugating medium of "No. 19" except that the amount of the paper strength enhancer added was changed to 0.05 [parts by weight]. rice field.
The corrugating medium of product number "No. 23" was prepared in the same way as the corrugating medium of "No. 19" except that the amount of the paper strength enhancer added was changed to 0.50 [parts by mass]. rice field.

The corrugating medium of product number "No. 24" was prepared in the same way as the corrugating medium of "No. 19" except that the amount of the paper strength enhancer added was changed to 3.00 [parts by mass]. rice field.
The corrugating medium of product number “No. 25” was prepared in the same way as the corrugating medium of “No. rice field.
Core raw paper of product number "No. 26" was prepared in the same manner as for core raw paper of "No. 19" except that the basis weight was changed to 120 [g/m ² ].
Core raw paper of product number "No. 27" was prepared in the same manner as the core raw paper of "No. 19" except that the basis weight was changed to 50 [g/m ² ].
Core raw paper of product number "No. 28" was prepared in the same manner as the core raw paper of "No. 19" except that the basis weight was changed to 210 [g/m ² ].

For core raw paper of product number “No. 29”, the basis weight was changed to 120 [g/m ² ], and miscellaneous waste paper was mixed at a ratio of 30 [mass%] and corrugated waste paper at a ratio of 70 [mass%]. The core raw paper was prepared in the same manner as the core raw paper of "No. 19" except that the pulp slurry was used.
The core raw paper of product number “No. 30” is the pulp slurry of “No. It was made in the same way as the corrugating medium.

Corrugating medium of product number "No. 31" was prepared in the same manner as corrugating medium of "No. 29" except that the basis weight was changed to 160 [g/m ² ].
The corrugating medium of product number "No. 32" was prepared in the same manner as the corrugating medium of "No. 19" except that the amount of the paper strength enhancer added was changed to 0.10 [parts by weight]. rice field.
The corrugating medium of product number "No. 33" was prepared in the same way as the corrugating medium of "No. 19" except that the amount of the paper strength enhancer added was changed to 4.00 [parts by weight]. rice field.

The product number of the liner base paper and the product number of the core base paper used in each of the corrugated cardboard materials to be measured in Examples 1 to 22 and Comparative Examples 23 to 32 are specifically shown in Table 3 below. In Table 3 below, the "type" item of the liner and the "type" item of the corrugating medium include the product numbers of the liner base papers (the above One of the product numbers "No. 1" to "No. 18") and the product number of the corrugating medium (one of the above product numbers "No. 19" to "No. 33") are indicated. there is The product number shown in the "type" item of the liner base paper is used for each of the front liner and back liner of the cardboard material to be measured.

Basis weight of liner base paper used for corrugated cardboard materials measured in Examples 1 to 22 and Comparative Examples 23 to 32, amount of strength enhancer added to liner base paper, basis weight of corrugating medium, strength enhancement of corrugating medium Specifically, the additive amount of the agent is as shown in Table 4 below.
Then, the length-weighted average fiber length and Runkel ratio shown in Table 4 below were measured for the liner base paper and core base paper used for each of the corrugated cardboard materials to be measured in Examples 1 to 22 and Comparative Examples 23 to 32. rice field.

The length-weighted average fiber length is the average value of the length (fiber length) of pulp fibers constituting liner base paper and core base paper, and is measured according to JISP8226-2:2011.
The Runkel ratio is a parameter indicating the shape of the pulp fibers forming the corrugating medium, and is calculated by (Runkel ratio)=(twice the fiber wall thickness)/(fiber lumen diameter). A higher Runkel ratio indicates a stiffer fiber.
Length weighted average fiber length and Runkel ratio were adjusted using the following fiber classifier.
・ Fiber classifier: product name “MAX-F700”, manufactured by Aikawa Iron Works Co., Ltd.

The Runkel ratio and the length weighted average fiber length were measured by the following procedures A1-A5.
Procedure A1: Cut out the second tier from the top of the cardboard material to a 40 [cm] square, and cut the 40
A [cm] square cardboard sheet was used for the measurement. Cutout position is cardboard
centered in the seat width. Then, put the cardboard sheet in ion-exchanged water.
Immerse for 15 minutes and remove from deionized water.
Procedure A2: Each of the core base papers from the cardboard sheet taken out in Procedure A1 is
It is separated from the liner base paper by peeling it off by hand so that the base paper does not tear.
Procedure A3: The core raw paper separated in Procedure A2 is immersed in deionized water, and the concentration is 2 ± 0.2 [%
] and soaked for 24 hours.
Procedure A4: After soaking the corrugating medium whose concentration has been adjusted according to Procedure A3 for 24 hours,
220-1: 2012 standard type disaggregator (part number No. 2580-A
, manufactured by Kumagai Riki Kogyo Co., Ltd.) for 20 minutes to separate the pulp into fibers.
understand.
Procedure A5: Separate the slurry (pulp fiber) after disaggregation in Procedure A4, and measure the fiber length as follows
Using a machine, the Runkel ratio and conforming to JISP8226-2:2011
The length-weighted average fiber length was measured.
・Fiber length measuring machine: Product number FS-5 UHD base unit, manufactured by Valmet

---evaluation---
For the corrugated cardboard materials to be measured in Examples 1 to 22 and Comparative Examples 23 to 32, "difficulty in crushing after carton making", "ease of crushing after carton making", and "bellows foldability" described below were evaluated. evaluated.
"Difficulty in crushing after carton making" is an evaluation criterion corresponding to the load resistance of a cardboard box.
The cardboard box to be evaluated is a box assembled by hand (handmade) from the following evaluation cardboard pieces.

A method of manually assembling a cardboard box is to fold cut evaluation cardboard pieces at predetermined ruled lines, attach them with a hot-melt adhesive, and form a box.
The method of assembling the evaluation cardboard pieces by the box-making system is the same regardless of whether it is manually assembled or assembled by the box-making system. Therefore, it is assumed that the "resistance to crushing after carton making" of the evaluation cardboard pieces assembled by hand has a correlation with "the crushing resistance after carton making" of the evaluation corrugated pieces assembled by the carton making system. I can say

"Evaluation cardboard pieces" are box-making test pieces obtained by punching the following number of cardboard materials into the following shapes and sizes with a sample cutter (Mimaki Engineering Co., Ltd., CF2-1218).
・Shape: A pattern in which a type A cardboard box is deployed ・Size: Width of side plate of A type cardboard box 170 [mm]
The width of the end plate of the A-type cardboard box is 255 [mm],
Height dimension of A type cardboard box 350 [mm]

The evaluation cardboard piece punched into the above shape is provided with the following creases.
Crease: A crease exists in the center of the side plate on either of the two sides of the side plate,
The center of the side plate is the position 85 [mm] from the edge of the side plate
Folds extend along the height of the box

The above creases are applied to the measurement cardboard materials (evaluation cardboard pieces) of Examples 1 to 22 and Comparative Examples 23 to 32 in either of the following modes α or β. A box assembled from such creased evaluation cardboard pieces has a creased portion on either side of the box. This box is called a "folded cardboard box".
Aspect α: Position 85 [mm] from the edge of the end plate that is the center of the side plate (the center of the width dimension
Part) is folded by hand 180 [°]. then expand,
Give creases.
Aspect β: Position 85 [mm] from the edge of the end plate that is the center of the side plate (the center of the width dimension
part) is folded by hand 180 [°], and in that state 24 o'clock
hold for a while. After that, it is unfolded and creases are given.
In the above Table 3, the item "Creasing Method" indicates which mode α or β is applied to Examples 1 to 22 and Comparative Examples 23 to 32, respectively.

In order to evaluate “difficulty in crushing after carton making”, a test is carried out according to the following procedures B1 to B4.
・Procedure B1: Weight 10 in a type A cardboard box created using evaluation cardboard pieces
Put the following weight [kg] and attach it to the bottom with hot melt adhesive.
and seal it so that a load is applied to the entire bottom surface of the A-type cardboard box.
> Weight: Poly bag (Product number: VX29-HCL, Dimensions: 520 [mm wide
], length 600 [mm], thickness 0.02 [mm], Japan Sanipa
10 [L] of tap water is added to the (manufactured by Cook Co., Ltd.), and the water is spilled.
I made it by tying the bag so that it would not come out.
・Procedure B2: Prepare 5 [pieces] of cardboard boxes from step B1, and 5 [pieces] of cardboard boxes
Stack up 5 [stages] so that there is no gap. In other words, the bottom cardboard box
A load of about 40 [kg] is applied to the box.
・Procedure B3: Allow to stand for 24 hours in the state of procedure B2, and check the state of the bottom cardboard box.
Confirm.
・Procedure B4: Procedures B1 to B3, Examples 1 to 22 and Comparative Examples 23 to 32
Evaluation cardboard pieces manufactured using each measurement cardboard material
1 [time] for each cardboard box.

"Difficulty in crushing after carton making" is evaluated according to the following criteria.
◎: There is no change in the cardboard box before and after the test (no crushing, dents, or scratches)
・○: One of the top surface and the side surface, or both the top surface and the side surface, the cardboard is crushed.
Geta (distorted, concave)
・△: The cardboard is torn on either the top or side, or both the top and side.
X: The cardboard box was crushed. In the "difficulty of crushing after carton making", "O" or higher was evaluated as good, and "△" or lower was evaluated as unsatisfactory.

"Ease of crushing after carton making" is an evaluation criterion corresponding to the ease of compressing a cardboard box after carton making.
In order to evaluate the ease of crushing after carton making, a compression test is performed on the cardboard box according to the following procedures C1 and C2.
・Procedure C1: Assemble the A-type cardboard box manually. The A-type cardboard box is described above.
100
[Box] Create.
・Procedure C2: Put the cardboard box assembled in the procedure C1 into the following cardboard box crushing machine
The cardboard boxes that were thrown in were clogged in the cardboard box crushing machine.
In other words, the datum into which the cardboard box crusher is thrown
Observe whether it stops without crushing the cardboard box.
> Corrugated cardboard box crushing machine: Product number M780R-1200P, Shi Co., Ltd.
Made in Russia

In the evaluation of "ease of crushing after carton making", one set of 1 [times] test using the cardboard box of mode α and 1 [time] test using the cardboard box of mode β (1 [time ]), and if the machine is stopped without collapsing in either aspect α or aspect β, it is judged to be "clogged".
The ease of crushing after carton-making was evaluated according to the following criteria.
・A: During 100 [times], all were able to be crushed.
○: 1 out of 100 [times], the cardboard box was jammed.
△: 2 to 4 [times] out of 100 [times] the cardboard box was clogged.
・×: 5 [times] or more out of 100 [times], the cardboard box was clogged.
In the "ease of crushing after carton making", "○" or higher was evaluated as good, and "△" or lower was evaluated as unsatisfactory.

"Accordion foldability" is an evaluation criterion corresponding to the quality of the appearance near the crease of the corrugated cardboard material folded in an accordion fold.
The corrugated cardboard material to be evaluated was manufactured by folding a double-sided corrugated board web manufactured in the following manufacturing process into a bellows fold in the following folding process.
A well-known corrugator with a single facer and a double facer is used for the production of measuring corrugated board by manufacturing process.

The manufacturing process is carried out according to procedures D1 to D4 below.
・Procedure D1: forming corrugations (wavy lines) on corrugating medium supplied from corrugating medium rolls,
An adhesive is applied to the apex of the formed step.
・Procedure D2: Back liner base paper roll for core base paper coated with adhesive in procedure D1
The liner base paper for the back liner supplied from the
and heat-bond to form a single-sided cardboard or web (sing
processing in Rufacer).
・Procedure D3: On the core side of the single-sided corrugated cardboard web formed in Procedure D2, the original for the front liner is applied.
The liner base paper for the front liner supplied from the paper roll is pasted with an adhesive,
This is pressed and heated with pressure and heating rolls to bond, and double-sided dan
Create a ball web (processing with a double facer).
・Procedure D4: For the double-sided corrugated cardboard web created in Procedure D3, it is constant in the extension direction
Folds are formed that are spaced apart and extend in the width direction.

Pressurization and heating in the procedures D2 and D3 are performed, for example, under the following conditions.
>Procedure D2 (Single Facer)
・Heating temperature 120 to 200 [°C]
・Roll linear pressure 20 to 40 [kN/m]
・ Pressurization time 0.01 to 0.20 [seconds]
>Procedure D3 (double facer)
・Heating temperature 120 to 200 [°C]
・Roll linear pressure 0.1 to 1.0 [kN/m]
・Pressure time 2 to 7 [seconds]

As the adhesive for laminating the liner base paper and core base paper in the above procedures D1 and D2, a one-tank starch paste, which is commonly used, was used.
An emulsion such as a synthetic resin may be used for laminating the liner base paper and core base paper. Specific examples of synthetic resins include polyethylene, polypropylene, polyamide, polyester, ethylene-unsaturated carboxylic acid copolymer, styrene-butadiene copolymer, butadiene-acrylonitrile copolymer, styrene-butadiene-acrylonitrile copolymer, poly Vinyl acetate, ethylene-vinyl acetate copolymer, polyacrylic acid ester copolymer, styrene-acrylic acid ester copolymer and the like can be mentioned.

In addition, as a method of laminating the liner base paper and core base paper in steps D1 and D2, an adhesive layer is formed by subjecting the liner base paper or core base paper to extrusion lamination or coating with a synthetic resin emulsion. Then, a method of polymerizing the liner base paper and the core base paper, or a method of interposing a synthetic resin film between the liner base paper and the core base paper and bonding them by applying pressure and heat may be adopted.

The double-faced corrugated cardboard web produced in the manufacturing process including the above steps D1 to D4 is folded into a bellows fold in the folding step including the following steps E1 and E2. In this folding step, the following folding device is used at the following transport speed.
- Folding device: manufactured by BHS Corrugated Machinery,
Product number "AS-F",
・Conveyance speed: 100 [m/min]
・Procedure E1: After the procedure D4, the double-sided corrugated cardboard web is folded by the above folding device.
transport to
・Procedure E2: Alternately folding back the double-sided corrugated cardboard web conveyed in Procedure E1 at the creases
, folded into a bellows fold, measuring cardboard of the above-mentioned size (packing dimensions)
Create materials.
According to procedures D1 to D4, E1 and E2, corrugated cardboards for measurement of Examples 1 to 22 and Comparative Examples 23 to 32 are prepared.

The appearance of each measured corrugated cardboard prepared in the above procedure E2 was visually confirmed, and the bellows foldability was evaluated according to the following criteria.
・ ☆: No voids were found near the folds of the cardboard material to be measured, and 1 [cm] or more was found between the sheets.
There was not even one lateral deviation of
・◎: No voids were found near the folds of the cardboard material to be measured, and the distance between the sheets was 2 [cm] or more.
There was not even one lateral deviation of

○: One or more voids are found near the fold of the cardboard material to be measured, and 2 [cm] between sheets
There was not even one such lateral shift.
・△: 1 horizontal deviation of 2 [cm] or more and 5 [cm] or less between sheets of cardboard material for measurement
there was more than one.
・×: One or more horizontal deviations exceeding 5 [cm] between sheets of cardboard material for measurement
Were present.

The above-mentioned gap is a gap that exists 15 [mm] inside from the folded end of the cardboard material to be measured.
In the "accordion foldability", "○" or higher was evaluated as good, and "Δ" or lower was evaluated as unsatisfactory.
In addition, the corrugated cardboard material for which the evaluation of "bellows folding property" corresponds to "x" (the corrugated cardboard material for which there is one or more lateral misalignments exceeding 5 [cm] between sheets) was processed by a box-making system (CMC carton wrap). 100, manufactured by CMC), when paper is fed at a box-making speed of 500 [boxes/hour], transport failures such as meandering of the cardboard material to be measured and sheet folding due to forced meandering occur. It was confirmed that the machine stop occurs when

In Examples 1 to 22, the basis weight of the liner is 80 [g/m ² ] or more and 270 [g/m ² ] or less, and the length-weighted average fiber length of the liner is 0.90 [mm] or more. is 1.50 [mm] or less, the Runkel ratio of the liner is 1.20 or more and 1.60 or less, and the amount of the paper strength enhancer added to the liner is 0.15 [parts by mass] or more is 5.25 [parts by mass] or less, and the basis weight of the core is 80 [g/m ² ] or more and 180 [g/m ² ] or less, and the weight of the length of the core The average fiber length is 0.86 [mm] or more and 1.24 [mm] or less, the Runkel ratio of the core is 0.96 or more and 1.29 or less, and the paper strength of the core is increased The amount of agent added is 0.01 [parts by mass] or more and 3.90 [parts by mass] or less, and the "difficulty in crushing after box making", "ease of crushing after box making", and "bellows folding A good evaluation of "○" or higher was obtained in all of "goodness".

In Examples 9 to 12, the amount of the paper strength enhancer added to the liner was 0.90 [parts by mass] or more and 4.00 [parts by mass] or less. Excellent evaluations of "A" or higher were obtained in all of "Ease of crushing after carton making" and "Accordion foldability".
In particular, in Examples 10 and 11 in which the amount of the paper strength enhancer added to the liner was 1.25 [parts by mass] or more and 3.30 [parts by mass] or less, the "bellows foldability" was the highest with "☆". Highly rated.
In Examples 15 and 16, the amount of the paper strength enhancer added to the core was 0.40 [parts by mass] or more and 3.10 [parts by mass] or less, and "difficulty in crushing after box making" An excellent evaluation of "⊚" was obtained for both "ease of crushing after carton making" and "bellows foldability".

On the other hand, in Comparative Example 23, in which the basis weight of the liner is less than 80 [g/m ² ] and the basis weight of the core is less than 80 [g/m ² ], "difficulty in crushing after box making" and "bellows foldability" were evaluated poorly.
In Comparative Examples 24 and 25, in which the basis weight of the liner is greater than 270 [g/m ² ] and the basis weight of the core is greater than 180 [g/m ² ], "ease of crushing after box making" and "bellows foldability" were evaluated poorly.

The length-weighted average fiber length of the liner is less than 0.90 [mm] and the Runkel ratio is less than 1.20, and the core length-weighted average fiber length is less than 0.86 [mm]. In Comparative Examples 26 and 28 in which the ratio was smaller than 0.96, a poor evaluation was obtained in terms of "difficulty in crushing after box making".
The length-weighted average fiber length of the liner is greater than 1.50 [mm] and the Runkel ratio is greater than 1.60, and the core length-weighted average fiber length is greater than 1.24 [mm]. In Comparative Example 27, in which the ratio was greater than 1.29, a poor evaluation was obtained in terms of "ease of crushing after carton making."

In Comparative Example 29 in which the liner paper strength agent is less than 0.15 [parts by mass] and in Comparative Example 31 in which the core paper strength agent is less than 0.01 [parts by mass], "collapse after box making Poor evaluations were obtained in terms of "hardness" and "bellows foldability".
In Comparative Example 30 in which the liner paper strength agent is greater than 5.25 [parts by mass] and in Comparative Example 32 in which the core paper strength agent is greater than 3.90 [parts by mass], "crushing after box making Poor evaluations were obtained in terms of "easiness" and "bellows foldability".

From Comparative Example 23, when the grammage of the liner is less than 80 [g/m ² ] and the grammage of the core is less than 80 [g/m ² ], the strength of the measured corrugated board is insufficient. The strength of the manufactured box is not ensured, and the hardness of the liner and the core is insufficient, so that it breaks at a point different from the intended fold, and lateral slippage between sheets tends to occur. It is presumed that the appearance is likely to be damaged.
From Comparative Examples 24 and 25, when the basis weight of the liner is greater than 270 [g/m ² ] and the basis weight of the core is greater than 180 [g/m ² ], it is necessary to crush the cardboard box. It is presumed that the external force becomes excessively large, making it difficult to crush the corrugated cardboard box after carton making, and that the liner and core are too hard and the appearance is likely to be damaged near the fold.

From Comparative Examples 26 and 28, the length-weighted average fiber length of the liner is less than 0.90 [mm], the Runkel ratio is less than 1.20, and the length-weighted average fiber length of the core is 0.86. If it is smaller than [mm] and the Runkel ratio is smaller than 0.96, it is assumed that the strength of the measured cardboard material is insufficient and the strength of the manufactured box is not ensured.
From Comparative Example 27, the length-weighted average fiber length of the liner is greater than 1.50 [mm], the Runkel ratio is greater than 1.60, and the length-weighted average fiber length of the core is 1.24 [mm]. If the Runkel ratio is greater than 1.29, the external force required to crush the cardboard box becomes excessively large, making it difficult to crush the cardboard box after carton making.

From Comparative Examples 29 and 31, when the paper strength agent in the liner is less than 0.15 [parts by mass], or when the paper strength agent in the core is less than 0.01 [parts by mass], the measured cardboard Due to insufficient strength of the material, the strength of the manufactured box cannot be ensured, and due to insufficient hardness of the liner and core, it breaks at a point different from the intended crease, resulting in lateral slippage between the sheets. It is presumed that the appearance is likely to be damaged in the vicinity of the crease.
From Comparative Examples 30 and 32, when the paper strength agent in the liner is greater than 5.25 [parts by mass], or when the paper strength agent in the core is greater than 3.90 [parts by mass], the cardboard box It is presumed that the external force required for crushing becomes excessively large, making it difficult to crush the cardboard box after carton making, and that the liner and core are too hard and the appearance is easily damaged near the folds.

From Examples 1 to 24 in view of Comparative Examples 23 to 32, the basis weight of the liner is 80 [g/m ² ] or more and 270 [g/m ² ] or less, and the length weighted average fiber of the liner The length is 0.90 [mm] or more and 1.50 [mm] or less, the Runkel ratio of the liner is 1.20 or more and 1.60 or less, and the amount of the paper strength enhancer added to the liner is 0.15 [parts by mass] or more and 5.25 [parts by mass] or less, and the basis weight of the core is 80 [g/m ² ] or more and 180 [g/m ² ] or less The length-weighted average fiber length of the core is 0.86 [mm] or more and 1.24 [mm] or less, and the Runkel ratio of the core is 0.96 or more and 1.29 or less Yes, and the amount of the paper strength enhancer added to the core is 0.01 [parts by mass] or more and 3.90 [parts by mass] or less, making it difficult to crush the cardboard box and easy to crush the cardboard box. It can be said that all of the bellows foldability can be ensured.

Examples 1 and 8 to 13 differ from each other in the amount of the paper strength agent added to the liner, and are otherwise common. From Examples 9 to 12 in view of Examples 1, 8, and 13, the addition amount of the paper strength agent to the liner is 0.90 [parts by mass] or more and 4.00 [parts by mass] or less , the difficulty of crushing the cardboard box, the ease of crushing the cardboard box, and the bellows foldability are all improved.
In particular, according to Examples 10 and 11, when the amount of the paper strength enhancer added to the liner is 1.25 [parts by mass] or more and 3.30 [parts by mass] or less, the bellows folding property is further improved. It can be said that

Examples 1 and 14 to 17 differ from each other in the amount of the paper strength agent added to the corrugating medium, and are otherwise common. From Examples 15 and 16 in view of Examples 1, 14, and 17, the amount of the paper strength enhancer added to the core is 0.40 [parts by mass] or more and 3.10 [parts by mass] or less. Therefore, it can be said that all of the difficulty of crushing the cardboard box, the ease of crushing the cardboard box, and the bellows foldability are improved.

In addition, from Examples 1, 20, and 21 having different flute types, if the flute is any one of A, B, and AC, the difference in flute type is the difficulty in crushing the cardboard box and the crushing of the cardboard box. It can be said that it does not easily affect the evaluation of ease and bellows foldability.
From Examples 1 and 22 in which the creasing method is different from each other, it can be said that the difference in the creasing method does not affect the evaluation of the difficulty of crushing the cardboard box, the ease of crushing the cardboard box, and the bellows folding property. . It can be said that any method can be adopted as the method of folding the corrugated cardboard for measurement because the difference in the way of making the creases does not affect the evaluation.

[III. Modification]
The above-described embodiment is merely an example, and there is no intention to exclude various modifications and application of techniques not explicitly described in this embodiment. Each configuration of this embodiment can be modified in various ways without departing from the gist thereof. In addition, they can be selected as necessary, and can be combined as appropriate.
For example, when corrugated cardboard is used as a material for a box-making system, it is preferable that no additional processing such as intentionally formed cuts or perforations is applied to the folds, and the surface layer of the liner in the corrugated cardboard is preferably It is preferable that the crease is formed by folding back 180[°] starting from the provided ruled line (for example, with the ruled line inside). On the other hand, when the corrugated cardboard is a material other than for a box-making system, processing such as notches and perforations may be applied to the folds.

The liner base paper and core base paper used for the above-described corrugated cardboard and measurement corrugated cardboard are not limited to the products with the product numbers given as examples, but also the liner base paper produced by the method for manufacturing a liner for corrugated board disclosed in Japanese Patent No. 6213364, Japanese Patent Application Laid-Open No. 2017. Core raw paper prepared by the method for manufacturing corrugated board base paper disclosed in JP-A-218721 may also be used.

1 cardboard material 10th row (wavy)
2 sheet 20 sheet pair 21 first sheet 22 second sheet 23 third sheet F fold L1 vertical dimension (first dimension)
L2 lateral dimension (second dimension)
L3 Height dimension (third dimension)

Predetermined configurations corresponding to the above viewpoints and problems 1, 2, and 3 include configurations described below.
・Configuration: Configuration 1 and Configuration 2 below
> Configuration 1: The liner has the following configurations 1A to 1D
Configuration 1A: The basis weight is within a predetermined first basis weight range
Configuration 1B: The length- weighted average fiber length of the fiber length is within a predetermined first length range
Configuration 1C: The Runkel ratio is within a predetermined first ratio range
Configuration 1D: The addition amount of the paper strength agent is within the predetermined first addition amount range> Configuration 2: The core has the following configurations 2A to 2D
Configuration 2A: The basis weight is within a predetermined second basis weight range
Configuration 2B: The weighted average fiber length of the fiber length is in the second range of the predetermined length
Configuration 2C: The Runkel ratio is in a predetermined second ratio range
Configuration 2D: The addition amount of the paper strength agent is within the predetermined second addition amount range

“Basis weight” is a parameter corresponding to the weight per unit square meter [g/m ² ] of the liner and core that constitute the corrugated board 1 . As the basis weight increases, the hardness and strength of the liner and core tend to increase, and as the basis weight decreases, the hardness and strength of the liner and core tend to decrease.
“Length- weighted average fiber length” is a parameter corresponding to the average value of the lengths (fiber lengths) of pulp fibers contained in the liner and core forming the corrugated board 1 .
When the fiber length value is large, the pulp fibers tend to become entangled with each other, and the hardness of the liner and core tends to increase. When the fiber length value is small, the pulp fibers are less likely to entangle with each other, and the flexibility of the liner and core tends to increase.

If at least one of the grammage of the liner or core, the length- weighted average fiber length, the Runkel ratio, or the amount of the strength agent added is below the specified range, the strength of the liner or core is insufficient. sufficient and tends to lead to problems 1 and 3 above.
If at least one of the grammage of the liner or core, the length- weighted average fiber length, the Runkel ratio, or the amount of the paper strength agent added exceeds a predetermined range, the strength of the liner or core is excessive. , which tends to lead to problems 2 and 3.

Claims (5)

A rectangular sheet of continuous double-sided corrugated cardboard is folded back in a second direction orthogonal to the first direction at each of the folds extending linearly along the first direction along the plane along the folds. A bellows-folded corrugated cardboard material in which the sheets are stacked along a third direction orthogonal to both the one direction and the second direction,
The basis weight of the liner constituting the double-sided corrugated cardboard is 80 [g/m ² ] or more and 270 [g/m ² ] or less,
The weighted average fiber length of pulp fibers of the liner is 0.90 [mm] or more and 1.50 [mm] or less,
The Runkel ratio of the pulp fibers of the liner is 1.20 or more and 1.60 or less,
The amount of the paper strength enhancer added to the liner is 0.15 [parts by mass] or more and 5.25 [parts by mass] or less,
The basis weight of the core constituting the double-sided corrugated cardboard is 80 [g/m ² ] or more and 180 [g/m ² ] or less,
The length-weighted average fiber length of the core is 0.86 [mm] or more and 1.24 [mm] or less,
The Runkel ratio of the core is 0.96 or more and 1.29 or less,
A corrugated board, wherein the amount of the paper strength agent added to the core is 0.01 [parts by mass] or more and 3.90 [parts by mass] or less. 2. The corrugated board material according to claim 1, wherein the amount of the paper strength enhancer added to the liner is 0.90 [parts by mass] or more and 4.00 [parts by mass] or less. 2. The corrugated cardboard material according to claim 1, wherein the amount of the paper strength enhancer added to the liner is 1.25 [mass parts] or more and 3.30 [mass parts] or less. Any one of claims 1 to 3, wherein the amount of the paper strength agent added to the core is 0.40 [parts by mass] or more and 3.10 [parts by mass] or less. Corrugated cardboard material described in paragraph. A cardboard box using the cardboard material according to any one of claims 1 to 4.

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