JP2001105516A - Corrugated cardboard sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a corrugated cardboard sheet capable of preventing the cracking of a rule. SOLUTION: In a corrugated cardboard sheet wherein liners and corrugated core are integrated, at least one of the liners comprises stretched paper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corrugated cardboard sheet used as a packaging material and capable of preventing a ruled line from breaking.

[0002]

2. Description of the Related Art A corrugated cardboard sheet is a structure composed of a combination of a corrugated core and a liner, and is generally used for double-sided corrugated cardboard, which is widely used as a material for boxes and the like, and for heavy loads. Double-sided cardboard, double-sided cardboard, and the like.

[0003] Such a corrugated cardboard sheet is punched into a predetermined shape by a box-making machine, a ruled line is formed in a bent portion, and a glued portion is attached to form a corrugated cardboard case. By the way, the corrugated cardboard sheet is bent at the ruled line portion when making the box or when assembling the corrugated cardboard case. At this time, since a stretching force acts on the front liner outside the box of the corrugated cardboard sheet, the front liner may be broken at a ruled line portion. For mild ones, the surface layer of the liner becomes cracked,
In severe cases, all layers of the liner break. This phenomenon is called ruled line cracking. Ruled line cracks occur when the corrugated cardboard sheet is folded, because the liner outside the bent portion is stretched more than the breaking elongation, so that the surface layer portion of the liner, and in some cases, all layers are broken. This phenomenon is likely to occur when the water content of the paper is 6% or less. This is because when the moisture decreases, the elongation of the paper decreases. Therefore, creases are particularly likely to occur when corrugated cardboard is exposed to harsh drying conditions in a corrugator or during the dry season in winter. As a countermeasure against this, conventionally, for a liner of corrugated cardboard, measures have been taken such as changing to a pulp blend containing a lot of softwood, increasing synthetic resin fibers, or weakening interlayer strength in order to increase the breaking elongation of the liner base paper. Also, at the time of box making, spraying water with a corrugator for the purpose of preventing over-drying of the cardboard sheet, or making the box immediately after laminating the cardboard sheet,
In addition, it was necessary to take measures such as applying steam to the sheet during coating and applying a humectant such as polyethylene glycol.

[0004]

Accordingly, there has been a need for a cardboard which can suppress the occurrence of cracks in the ruled line without performing any special treatment such as water spraying or chemical application during cardboard processing or packaging.

[0005]

In order to solve the above problems, the present invention has the following arrangement. That is, the present invention is a corrugated cardboard sheet obtained by integrating a liner and a corrugated core, wherein at least one liner is a stretched paper.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The inventor of the present invention has a large elongation at break,
As a result of searching for various types of paper that are used as a liner for corrugated boards and that do not cause creases, they found that stretched paper was suitable and arrived at the present invention. The stretched paper referred to herein is paper that has been given a stretching performance in the paper flow direction or width direction by finely shrinking the paper on a paper machine. Some of them are included in Kraft paper 5 types 1 and 2 of Japanese Industrial Standard P3401 "kraft paper". It should be noted that since this standard relates to paper bags for heavy packaging, it does not include all stretched papers applicable to the present invention. The stretched paper according to the present invention has a rice basis weight of 50 to 200 g / m ² , JIS-P
Elongation based on 8132 is 3-20%, preferably 5-1
It is preferably 0%. If the elongation is less than 3%, the effect of preventing the ruled line cracks aimed at by the present invention cannot be obtained. On the other hand, if it exceeds 20%, the elongation is too large, and the tension applied to the liner at the time of laminating corrugated cardboard causes trouble. The corrugated cardboard sheet of the present invention is composed of a stretched paper and a core. In the stretched paper and the core, the step top of the core and the liner surface are bonded with an adhesive. There is no particular limitation on the core base paper used in the present invention, and a core base paper having rice basis weight, thickness, water resistance and other appropriate properties can be arbitrarily used depending on the use of the corrugated cardboard sheet to be produced. The stretched paper used in the present invention, as an example, uses kraft pulp as a main raw material, and through a nip roll to a part of a dryer roll of a fourdrinier multi-cylinder paper machine or a fourdrinier Yankee type paper machine, has an endless thick paper. An apparatus obtained by attaching a device for pressing and rotating a rubber belt, passing a wet paper between the dryer and the belt, and contracting the belt by using the contraction of the belt that has been stretched in advance is exemplified. The stretched paper according to the present invention has a stretch ratio of 3 to 20%, preferably 5 to 10%, and has a basis weight, color,
Characteristics such as the presence or absence of a coat layer, the type of raw pulp, and the presence or absence of waste paper can be appropriately selected. In the present invention, as the adhesive for bonding the stretched paper and the core, conventionally used adhesives can be arbitrarily used. For example, starch, gum arabic, polyvinyl alcohol, carboxymethyl cellulose, vinyl acetate, SBR, N
Water-soluble or water-dispersible adhesives such as BR and mixtures thereof, stainless steel paste for cardboard production and other adhesives, solvent-based adhesives such as acrylic resin, silicone resin, epoxy resin, shellac, hot melt adhesives Agents, molten resins and the like can be used. In the present invention, a conventionally used corrugator can be used as a method for bonding the stretched paper and the core. In addition, the thickness of the corrugated cardboard sheet in the present invention is, in order from the thicker one, an A flute used for normal transportation, a B flute, a C flute, an E flute used for an interior or a decorative box, or a thinner. Any thickness such as a so-called mini-stage, micro-stage, or the like generally having a thickness of 0.5 to 1 mm or the like can be obtained. However, the present invention is particularly suitable for producing thin corrugated cardboard called mini corrugated, micro corrugated, etc. Stretched paper used as a liner in the present invention is slightly inferior in terms of rigidity and the like to ordinary cardboard liner base paper. In the case of corrugated cardboard, strength and the like are not so required, so that this point is not a problem at all. The corrugated cardboard sheet thus obtained can be compared with a conventional corrugated cardboard sheet in a ruled line forming process, a bending process, and a box forming process under dry conditions without performing water spraying, chemical application, or the like at the time of forming. Ruled line cracks do not occur, and the production efficiency is high, which also contributes to energy saving and resource saving.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of a corrugated cardboard sheet according to the present invention will be specifically described below based on embodiments.

Comparative Example 1 Using a kraft paper having a rice basis weight of 90 g / m ² as a liner, and using a corrugator as a core and a class A core base paper having a rice basis weight of 120 g / m ² , a double-faced corrugated cardboard having a thickness of 3 mm was used. Manufactured. This cardboard sheet is placed at 20 ° C, 15% R
After adjusting the humidity under the condition of H, a ruled line was formed by a platen die cutter using a punching die provided with a ruled line in a flow direction and a width direction of the cardboard sheet. When forming the ruled line, the flow direction,
When folded 180 degrees at both ruled lines in the width direction,
In each case, the ruled line strength of the platen die cutter was set so that partial ruled line cracking occurred.

<Example 1> Stretched paper having a rice basis weight of 90 g / m ² (elongation: 7% in length and 7% in width) was used as a liner, and the rice basis weight was 120 g / m ^2.
A ^2- mm corrugated cardboard sheet having a thickness of 3 mm was produced using a m2 A-class core base paper as a core and using a corrugator. This cardboard sheet was conditioned at 20 ° C. and 15% RH, and then ruled lines were formed with the same ruled line strength as in Comparative Example 1. When the sheet was bent at 180 degrees at the ruled line portions in the flow direction and the width direction, ruled line cracks did not occur in any case.

Comparative Example 2 A kraft paper having a rice basis weight of 90 g / m ² was used as a liner, a class A core base paper having a rice basis weight of 115 g / m ² was used as a core, and a 1.2 mm thick corrugator was used. A double-sided cardboard was manufactured. This cardboard sheet is placed at 20 ° C, 15
After humidity control under the condition of% RH, a ruled line was formed in the same manner as in Comparative Example 1. When forming the ruled line, the ruled line strength of the platen die cutter was set so that when the line was bent at 180 degrees at both the ruled line portions in the flow direction and the width direction, a partial ruled line crack was generated.

<Embodiment 2> A 90 g / m ² stretched paper (elongation: 7% in length and 7% in width) is used as a liner, and the rice basis weight is 115 g / m2.
and corrugating the class A in corrugating of m ^2, and to produce a double-sided corrugated cardboard with a thickness of 1.2mm using a corrugator. This cardboard sheet was humidified under the conditions of 20 ° C. and 15% RH.
In the same manner as in the above, ruled lines were formed with the same ruled line strength. When the sheet was bent at 180 degrees at the ruled line portions in the flow direction and the width direction, ruled line cracks did not occur in any case.

[0012]

According to the present invention, it is possible to obtain a corrugated cardboard which can suppress occurrence of ruled line cracks without performing a special treatment such as water spraying or chemical application at the time of corrugating or forming.

Claims (1)

[Claims] 1. A corrugated cardboard sheet obtained by integrating a liner and a corrugated core, wherein at least one liner is made of stretched paper.