JP6213364B2 - Corrugated liner, method for increasing box compressive strength using this corrugated liner, and method for discriminating corrugated liner with high box compressive strength - Google Patents

Description

  The present invention improves the box compression strength by promoting delamination of the liner at the boundary portion between the side surface and the top surface and / or the bottom surface, in other words, the score portion (ruled line bent portion) when the cardboard box is compressed. Relates to a liner for corrugated board.

  Corrugated boxes are widely used as packaging materials used for transporting and storing industrial products and fruits and vegetables. One of the important quality items related to the design of a cardboard box is box compressive strength. As a method for improving the box compressive strength, it is conceivable to improve the compressive strength defined by JIS P 8126 of the base paper to be formed, that is, the liner or the core.

  On the other hand, when a liner or paperboard composed of multi-layer paper is joined with an adhesive, etc., a paper strength enhancer is sprayed toward the joint between wet papers to obtain the required adhesive strength. A method for improving the interlayer strength has been proposed (see Patent Document 1).

JP 2006-37288 A

  However, for example, when the compressive strength of a corrugated cardboard box manufactured using liners having the same core and different compressive strength is measured, the cardboard box using a liner having a high compressive strength necessarily has a higher compressive strength. There is no limit. This is considered to be due to the fact that factors other than the compressive strength are related as the physical properties of the liner affecting the box compressive strength.

  Therefore, the main object of the present invention is to provide a liner for corrugated cardboard capable of effectively expressing the box compressive strength.

  In order to solve the above problems, the present inventors have conducted extensive research on the properties of the liner that affects the compressive strength of the cardboard box. As a result, the lower the interlayer strength of the liner, the greater the compressive strength of the box. I found out. As a result of further studies, the present invention has been completed. That is, the present invention relates to the following cardboard liner.

  Item 1: A cardboard liner having at least two paper layers comprising a surface layer and a back layer, wherein the corrugated board is subjected to a box compression test according to JIS Z 0212 of a cardboard box formed using the liner. A cardboard liner, wherein delamination occurs between at least one of the layers of the liner at the boundary between the side surface and the top surface and / or the bottom surface before buckling of the side surface of the box.

  Item 2: JAPAN TAPPI No. Item 10. The cardboard liner according to Item 1, wherein the interlayer strength defined by 18-1 is 400 kPa or more and 600 kPa or less.

  Item 3: The cationic paper strength enhancer is contained at 0.1 to 1.2 parts by mass with respect to 100 parts by mass of the total pulp of the paper layer, and 50% by mass or more of the paper strength enhancer is on the surface layer. Item 3. A cardboard liner according to Item 1 or 2, which is contained.

  Item 4: The corrugated board liner according to any one of Items 1 to 3, wherein softwood kraft pulp is contained in a proportion of 20 to 90% by mass in the surface layer pulp.

  Item 5: The cardboard liner according to any one of Items 1 to 4, wherein softwood kraft pulp is contained in a proportion of 4.0 to 20% by mass in the total pulp of the paper layer.

Item 6: The cardboard liner according to any one of Items 1 to 5, wherein the number of paper layers is 2 to 5, and the basis weight of the liner is 160 to 340 g / m ² .

  Item 7: A method for increasing the box compression strength of a cardboard box using a cardboard liner having at least two paper layers consisting of a surface layer and a back layer, and in the case of a box compression test according to JIS Z 0212 of a cardboard box Further comprising the step of delamination between at least one of the layers of the liner at the boundary between the side surface and the top surface and / or the bottom surface until the side surface buckles the cardboard box. .

  Item 8: The method according to Item 7, wherein the cardboard liner according to any one of Items 2 to 6 is used.

  Item 9: A method for discriminating a cardboard liner having at least two paper layers composed of a surface layer and a back layer, and in a box compression test according to JIS Z 0212 of a cardboard box formed using the liner Compared to the case in which delamination occurs between at least one of the layers of the liner at the boundary portion between the side surface and the top surface and / or the bottom surface until buckling of the side surface of the cardboard box occurs. A method for discriminating whether the liner for cardboard has a high box compressive strength.

  The liner for cardboard of the present invention can effectively exhibit box compressive strength.

  The liner for cardboard in the present invention (hereinafter also simply referred to as a liner) has at least two paper layers comprising a surface layer and a back layer. The surface layer forms the surface of the corrugated cardboard sheet, and the back layer forms the back surface bonded to the core of the corrugated cardboard sheet. You may provide the middle layer formed between a surface layer and a back layer, and the surface lower layer formed between a surface layer and a middle layer.

  In the case of a box compression test in accordance with JIS Z 0212 of a cardboard box formed using the same, the liner in the present invention has a side surface and a top surface and / or a bottom surface before buckling of the side surface of the cardboard box. Delamination occurs between at least one of the layers of the liner at the boundary. Thereby, the remarkable effect which raises box compressive strength compared with what does not produce delamination is acquired. The reason why the compressive strength of the box is increased is not clear, but each layer of the delaminated liner is flexibly folded as the compression progresses, and the boundary between the side surface and the top surface and / or the bottom surface is easily supported by a flat surface. Is considered to improve the box compressive strength effectively. On the other hand, those that do not cause delamination are considered to be that the boundary portion is easily supported by points, and therefore the rotational rigidity is lowered, and the side surface is bent and buckled with a smaller compressive load. Here, the box compression test is based on a cardboard box having a flap. The effect of the present invention is not particularly limited to the flute configuration of the corrugated cardboard sheet.

  In the present invention, JAPAN TAPPI No. It is preferable to adjust the delamination by adjusting the interlayer strength defined by 18-1 to 600 kPa or less. Thereby, in the case of a box compression test, delamination can be generated with a compressive load smaller than the yield strength at which the side surface of the cardboard box buckles. On the other hand, by setting it as 400 kPa or more, it can suppress that the paper dust at the time of cutting, and the paper peeling at the time of box making and printing generate | occur | produce. Examples of the method for lowering the interlayer strength include relaxation of pulp beating, reduction of wet press pressure, reduction of paper strength enhancer, and the like.

  In the present invention, the cationic paper strength enhancer is contained at 0.1 to 1.2 parts by weight with respect to 100 parts by weight of the total pulp in the paper layer, and 50% by weight or more of the paper strength enhancer is in the surface layer. It is preferable to contain. More preferably, it is 0.2 to 1.2 parts by mass. Thereby, delamination can be adjusted by adjusting the interlayer strength of the liner to a preferred range. Moreover, since the effect which suppresses generation | occurrence | production of paper dust and paper peeling is also acquired by containing many cationic paper strength enhancers in a surface layer, what is necessary is just to contain in 50 to 100 mass%. Here, the total pulp of the paper layer is the sum of all pulps of two or more paper layers composed of at least a surface layer and a back layer. For example, when the pulp is composed of a surface layer and a back layer, It is the sum of the layers of pulp.

  The cationic paper strength enhancer is not particularly limited, and examples thereof include cationic chemicals such as cation-modified starch, polyamide / epichlorohydrin resin, polyethyleneimine resin, polyacrylamide resin, and polyamide resin. Various other anionic and amphoteric paper strength enhancers can be used in combination as long as the effects of the present invention are not impaired.

  In this invention, it is preferable that softwood kraft pulp is contained in the ratio of 20-90 mass% among surface pulp. More preferably, it is 20-60 mass%. Moreover, it is preferable that softwood kraft pulp is contained in the ratio of 4.0-20 mass% among the total pulp of a paper layer. More preferably, it is 4.0-10 mass%. Thereby, the interlayer intensity | strength of the surface layer containing a kraft pulp and the layer containing a used paper pulp can be adjusted, and it can adjust to a preferable range. Moreover, the effect which prevents ruled cracking is also acquired by increasing the content rate of a kraft pulp.

  The pulp constituting the back layer other than the surface layer, the middle layer, the front layer and the like is not particularly limited. For example, unbleached wood pulp, bleached chemical pulp, mechanical pulp, non-wood pulp, Kent waste paper, magazine waste paper, As appropriate, one or two or more selected from pulp obtained by deinking used paper such as used leaflet paper, used newspaper, office used paper, used information paper, used cardboard paper, used paperboard paper, used paperboard, and used paperboard Used. Waste paper pulp that is not deinked for the purpose of cost reduction and resource saving is generally used for the back layer in the case of 2 layers and in the middle layer in the case of 3 layers or more. It is desirable to use it.

  The pulp beating degree (CSF) is not particularly limited, but is preferably about 200 to 550 ml.

The number of paper layers of the liner preferably has three or more paper layers, but the upper limit is not particularly limited, and may be about 6 layers. The basis weight of the liner is preferably about 160 to 340 g / m ² . By setting it as 160 g / m < ² > or more, rigidity can be improved and body swelling can be suppressed. On the other hand, by setting it to 340 g / m ² or less, the moldability can be improved.

  The liner in the present invention is a paper layer made of two or more pulps as a main raw material to form a multilayer structure, but a known multilayer paper machine, for example, a long net former or a circular net former is combined. Can be produced by a paper machine. As long as the effects of the present invention are not impaired, the strength between the respective layers can be adjusted by spraying or coating an adhesive such as starch between the respective layers when the sheets are combined, It is preferred not to use starch.

  The method of increasing the box compression strength of a cardboard box using a cardboard liner having at least two paper layers consisting of at least a front layer and a back layer in the present invention is a box compression test according to JIS Z 0212 of a cardboard box. The method includes the step of causing delamination between at least one of the layers of the liner at the boundary portion between the side surface and the top surface and / or the bottom surface before buckling of the side surface of the cardboard box. By going through the step of causing delamination, the box compressive strength can be effectively expressed.

  In the present invention, as a method for increasing the box compressive strength, JAPAN TAPPI No. It is preferable to use a cardboard liner having an interlayer strength defined by 18-1 of 400 kPa or more and 600 kPa or less. Further, the cationic paper strength enhancer is contained in an amount of 0.1 to 1.2 parts by weight with respect to 100 parts by weight of the total pulp of the paper layer, and 50% by weight or more of the paper strength enhancer is contained in the surface layer. It is preferable to use a cardboard liner.

  Further, the present invention is a so-called screening method for a corrugated liner having a high box compressive strength. That is, the present invention is a method for discriminating a cardboard liner having at least two paper layers consisting of a surface layer and a back layer, and a box compression test according to JIS Z 0212 of a cardboard box formed using the liner In this case, the one that causes delamination between at least one of the layers of the liner at the boundary between the side surface and the top surface and / or the bottom surface before buckling of the side surface of the cardboard box does not occur Compared to the above, it is a method for discriminating that the liner has a high box compressive strength. As a result, the material and configuration of the cardboard liner can be designed appropriately.

  The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, “parts” and “%” represent “parts by mass” and “mass%”, respectively.

Example 1
Using softwood kraft pulp and corrugated used paper pulp as raw materials, paper making was performed using a multilayer paper machine to obtain a liner for cardboard having a basis weight of 280 g / m ² . Papermaking conditions include a cationic paper strength enhancer containing 0.5 parts by mass with respect to a total of 100 parts by mass of the total pulp in the paper layer, and a ratio of 25% by mass of softwood kraft pulp in the surface pulp. Contained. The cationic paper strength enhancer was all contained in the surface layer. Conifer kraft pulp was 6% by mass of the total pulp in the paper layer.

The compressive strength of the above corrugated board liner is set according to JIS P 8126, and the Z-axis strength (interlayer strength) is set according to JAPAN TAPPI No. It measured according to 18-1. Further, an A-stage double-sided cardboard sheet was obtained by pasting a general core of 160 g / m ² to this cardboard liner. Further, an A-type cardboard box having a box size of L / W / D and 375/255/180 mm was produced using this cardboard sheet, and the box compressive strength was measured according to JIS Z 0212. Furthermore, in the box compression test, it is visually observed whether the delamination occurs in the liner at the boundary between the side surface and the top surface and / or the bottom surface before buckling the side surface of the cardboard box. And evaluated.

Example 2
In the same manner as in Example 1, corrugated liners having different Z-axis strengths were obtained and subjected to various evaluations.

Comparative Example 1
A cationic paper strength enhancer is contained in an amount of 1.5 parts by mass with respect to a total of 100 parts by mass of all pulp in the paper layer. Produced a cardboard liner in the same manner as in Example 1. In addition, 30% by mass of the cationic paper strength enhancer was included in the surface layer. Conifer kraft pulp was 3.5% by mass of the total pulp in the paper layer. Further, various evaluations were performed in the same manner as in Example 1.

  The evaluation results of Example 1, Example 2, and Comparative Example 1 were as shown in Table 1.

Claims (7)

A liner for corrugated cardboard having at least two paper layers consisting of a surface layer and a back layer, wherein the cationic paper strength enhancer is 0.1 to 1.2 parts by mass with respect to 100 parts by mass of the total pulp of the paper layer. Part, and 50% by mass or more of the paper strength enhancer is contained in the surface layer. The interlayer strength specified in 18-1 is 400 kPa or more and 600 kPa or less, and the cardboard box formed using the liner undergoes buckling of the side surface of the cardboard box in a box compression test according to JIS Z 0212. A cardboard liner characterized by causing delamination between at least one of the layers of the liner at the boundary portion between the side surface and the top surface and / or the bottom surface. The liner for corrugated board of Claim 1 in which softwood kraft pulp is contained in the ratio of 20-90 mass% among surface pulp . The liner for corrugated board of Claim 1 or 2 in which conifer kraft pulp is contained in the ratio of 4.0-20 mass% among all the pulp of a paper layer . Number of layers of the paper layer is 2 to 5, the basis weight of the liner is 160~340g / ^{m 2,} cardboard liner according to any one of claims 1-3. A method for increasing the box compressive strength of a cardboard box using a cardboard liner having at least two paper layers comprising a surface layer and a back layer, wherein the cationic paper strength enhancer is 100 parts by weight of the total pulp of the paper layer 0.1 to 1.2 parts by mass, and 50% by mass or more of the paper strength enhancer is contained in the surface layer. When the interlaminar strength specified in 18-1 is 400 kPa or more and 600 kPa or less and the box compression test conforms to JIS Z 0212 of the cardboard box, the side and top surfaces And / or producing delamination between at least one of the layers of the liner at the interface with the bottom surface. 6. The method according to claim 5, wherein the cardboard liner according to any one of claims 2 to 4 is used. A method for discriminating a liner for corrugated board having at least two paper layers consisting of a surface layer and a back layer. The interlayer strength specified in 18-1 is 400 kPa or more and 600 kPa or less, and the cardboard box formed using the liner undergoes buckling of the side surface of the cardboard box in a box compression test according to JIS Z 0212. By the way, it is a liner for corrugated board having a higher box compressive strength than those that do not cause delamination between at least one of the layers of the liner at the boundary between the side surface and the top surface and / or the bottom surface. How to determine that.