JP2003247199A - Liner for corrugated cardboard - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of increasing initial adhesion of corrugated paper that can effectively develop an adhesion force, even when a paste of usual concentration is used without coating a linear and a core material with a thickener. <P>SOLUTION: The liner for corrugated cardboard has a burst index of ≥2.65 kPa.m<SP>2</SP>/g according to JIS P-8131 and a pulp water retention of ≤125% in the layer of up to 1/3 of the total thickness according to JAPAN-TAPPI No.26. In another corrugated cardboard, the specific burst index is ≥2.65 kPa.m<SP>2</SP>/g according to JIS P-8131 and the decreasing rate of xylene is ≥60%. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention mainly relates to fresh foods,
The present invention relates to a corrugated board liner used for a corrugated board sheet that is widely used as a material for a corrugated board box for packaging various products such as processed foods and home appliances.

[0002]

Corrugated board sheets are manufactured by a machine called a corrugating machine. This machine consists of two parts, a single facer (single-sided laminating machine) and a double facer (double-sided laminating machine, drying section, cooling section). In a single facer, starch paste is applied to the corrugated core raw paper top of the corrugated paper, and it is attached to a liner to form a single-faced cardboard. This single-faced cardboard is attached to another liner with a double facer to form a cardboard sheet. . When laminating single-sided corrugated board and liner, if the laminating speed becomes high, the amount of heat transferred to the starch paste from the hot plate will be insufficient and the gelatinization of the starch paste will be insufficient, or the starch paste will not dry after gelatinization. Inadequately, the adhesion immediately after laminating the core raw paper and the liner, that is, the initial adhesion becomes insufficient. If the initial adhesion is insufficient, crease lines may be inserted, the corrugated cardboard sheet may be cut to a predetermined size, or the liner and the core raw paper may peel off when the corrugated cardboard sheet is made. I have something to do. When such a trouble occurs, it is necessary to deal with it by reducing the laminating speed, so that the reduction of the production efficiency has been a problem.

As described above, the initial adhesion is one of the extremely important qualities in the production of corrugated cardboard sheets. In order to obtain a sufficient initial adhesive strength even when the laminating speed is increased, a method of mixing or applying a reactive viscosity improver or an alkali into the base paper to increase the initial adhesive strength and improve the laminating speed is disclosed in JP-A-56 -105952, JP-A-56-15915
4, JP-A-57-11042, JP-A-07-07
-195648 gazette. In addition, the pH of the bonding surface of the liner or core raw paper or both is 6
Japanese Unexamined Patent Publication No. 07-100977 discloses a method in which the initial adhesive strength is increased to 10 to increase the laminating speed. A method of applying a compound of sodium octaborate or the like as a laminating speed improver to the laminating surface of a liner or core raw paper to increase the initial adhesive strength and to improve the laminating speed is disclosed in JP-A-07-2906.
No. 22 publication. A method of applying a solution of polyhydric alcohol in borax as a laminating speed improver to increase the initial adhesive strength and to improve the laminating speed is disclosed in Japanese Patent Laid-Open No. 07-
It is disclosed in Japanese Patent No. 238263.

[0004] In all of these, chemicals for improving the water absorption of paper and absorbing water quickly or for arranging a thickening agent in the paper or on the surface of the paper are arranged. But,
In the study of the present inventors, a method for improving water absorption of paper is
It was found that the paste has a certain effect when the water content of the paste is low or when the bonding temperature is low, but it does not always exhibit the effect. The same applies to the method of using a chemical that thickens the glue, and it is not economical because the chemical is also placed in a portion not related to adhesion.

[0005]

SUMMARY OF THE INVENTION The present invention proposes a method for improving initial adhesion which is effective without applying a thickening agent to a liner or a core and which is effective even for a paste having a normal concentration.

[0006]

The present invention adopts the following method in order to solve the above problems. That is, the first aspect of the present invention is
The specific burst strength specified by JIS P-8131 is 2.6.
5 (kPa · m ² / g) or more, which is 1 of the total thickness from the bonding surface.
In layers up to / 3 thick, JAPAN-TAPPI
No. It is a liner for corrugated board in which the water retention of pulp specified by 26 is 125% or less.

A second aspect of the present invention is JIS P-81.
The specific burst strength specified in No. 31 is 2.65 (kPa · m ² / g) or more, and the xylene mass reduction rate according to the following test method is 60.
It is a liner for corrugated board which is more than%. Note: Test method A liner with a size of 70 cm ² is used as a sample, and the mass is measured. Then, the sample is thoroughly soaked in xylene, and the surface is lightly wiped to measure the mass. Immediately, place one side of the sample on the metal plate heated to 120 ° C so that one side of the sample adheres to the metal plate, and lightly press it on the top of the core of the single-sided corrugated board of the same size.
Measure the mass when heated for 2 seconds. The mass of xylene evaporated in this 10 seconds is divided by the mass of xylene that has soaked into the liner to obtain the xylene mass reduction rate.

A third aspect of the present invention is such that the weight of rice is 250 g / m ²
The liner for corrugated cardboard according to the second aspect of the present invention, which is the following and the reduction rate of xylene is 70% or more.

A fourth aspect of the present invention is JIS P-81.
31 has a specific burst strength of 2.65 (kPa · m ² / g) or more, and in a layer having a thickness from the bonding surface to 1/3 of the total thickness, JAPAN-TAPPI No. The second aspect of the present invention in which the water retention of the pulp specified by 26 is 125% or less.
The liner for corrugated board in any one of -3. It should be noted that P-8131 in the present invention is P-8131-1.
Means 995.

The starch paste used for bonding is composed of a carrier part and a main part. The carrier part is gelatinized carrier starch with caustic soda, and the main part is raw starch suspended in water. The carrier part and the main part are mixed and borax is added as a cross-linking agent to be used as a starch paste for bonding.

After the initial bonding, the corrugated cardboard sheet is peeled by 180 ° by hand at the frame tip after laminating, and the tester judges the quality based on the peeling resistance at that time and the state of the liner and the core raw paper after peeling. It is an evaluation that is performed in an extremely short time after bonding, and the elapsed time after bonding should not be long.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Water retention in the present invention means JA
It is defined by PAN-TAPPI No. 26. Water retention is a measure of how much the pulp is swollen, in other words, how much water it retains.

In the past, it was considered important to make paper absorb water quickly in order to improve the initial adhesion speed. It has also been proposed to increase the viscosity of the paste with a thickener. By the way, considering the relationship between the water retention on the surface of the liner base paper at the time of laminating and the initial adhesion rate, when the water retention of the pulp is high, the water content in the pulp increases, so it was heated for drying. A large amount of heat is spent on evaporation of water contained in the pulp. Therefore, the drying property when heated is deteriorated. On the contrary, when the water retention is low, the water content in the pulp is small, and when heated for drying, a large amount of heat is not required to evaporate the water. Therefore, the drying property is improved when heated. That is, it is presumed that it is possible to improve the initial bonding speed at the time of bonding by using a pulp that has good water absorption and hardly retains water as the pulp constituting the vicinity of the bonding surface of the liner base paper.

The liner has an adhesive surface (laminating surface) and a printing surface, and the adhesive surface is the back surface. 1/3 of the total thickness from the back
It was found from our diligent study that the water retention of pulp of up to about a layer affects the initial adhesion. In order for the initial adhesion to be good at the bonding speed at which sufficient production efficiency can be obtained, the water retention of the layer from the back surface to 1/3 of the total thickness is
It is necessary to be 125% or less, and more preferably 120% or less. On the other hand, when the water retention of the pulp exceeds 125%, the initial adhesion will not be good unless the bonding speed is lowered, and the initial adhesion will be poor at the bonding speed at which sufficient production efficiency can be obtained. Note that 90 μm may be adopted instead of the “thickness corresponding to 1/3 of the liner thickness”. Hereinafter, the paper layer of this portion may be abbreviated as “bonding surface layer”. The measuring method will be described in detail in Examples.

Regarding the commercially available class A liner, the water retention value of the bonding surface layer measured by this method is 126 to 130.
Imported liners are about 130-135, and commercial C-class liners are about 121-125.

In order to maintain the water retention of the laminating surface layer within this range, cornified waste paper pulp is added to the pulp used for papermaking.
0 mass% or more, preferably 65 mass% or more. The keratinized waste paper pulp may be used by selecting the corrugated waste paper pulp in the market, but it can be reliably obtained by heating at 120 ° C. or higher for 24 hours or longer. As another method to control the water retention of the bonding surface layer, select water resistant corrugated cardboard waste paper,
Examples thereof include a method of compounding the used paper pulp, a method of compounding synthetic resin fiber / pulp, and a method of mixing an appropriate amount of a water resistant agent or a water repellent agent with the pulp. In the present invention, the so-called A
It is also an important requirement to meet the specific burst strength required for a high-grade liner. For that purpose, it is possible to use long fiber NUKP or to add a paper strengthening agent in a larger amount than usual. Is. The liner may have one paper layer, but in order to satisfy both the water retention of the laminating surface layer and the specific burst strength of the paper, it is preferable to use a multi-layer paper. In the case of multi-layer papermaking, the water retention of the bonding surface layer can be controlled at the outermost layer and the specific burst strength can be controlled at the other layers.

Next, the mass reduction rate of xylene will be described. Soak the xylene into the liner thoroughly and apply 1 from the surface.
The mass reduction rate of xylene when heated at 20 ° C. for 10 seconds indicates in other words the ease of drying the pulp. It can be said that the larger the weight loss is, the easier the pulp is dried. Pulp that is easy to dry is a pulp that has good thermal conductivity.

When the mass reduction rate of xylene when the liner is sufficiently soaked with xylene and heated at 120 ° C. for 10 seconds from the surface is 60% or more, the drying property is good and sufficient production efficiency is obtained. The initial bonding becomes good at the obtained bonding speed. It is more preferably 65% or more, and most preferably 70% or more. On the other hand, if it is less than 60%, the drying property is poor, so the initial adhesion will not be good unless the bonding speed is reduced, and the initial adhesion will be poor at the bonding speed at which sufficient production efficiency can be obtained. .

The details of this measuring method will be described in Examples. The xylene mass reduction rate is a value that depends on the rice tsubo to some extent, but it is a commercially available class A liner (rice tsubo 250-280).
g / m ² ), this value is about 50-55%, imported liner (250-280 g / m ² ) is about 50-55%, and commercial C-class liner (210 g / m ² ) is 70%. %.

In order to make the xylene mass reduction rate within this range, it is effective to increase the density of the entire paper layer, and further beaten the keratinized waste paper pulp to be blended, or use NUKP having a Canadian standard freeness of 500 cc or less. Means of blending are preferred. Alternatively, a multi-layer papermaking method may be used in which the density of layers other than the bonding surface layer is made higher. In any case, the density of the entire paper layer is 0.80 or more, preferably,
It is about 0.84 to 0.9. Further, a method of blending a filler is also effective. Note that, as described above, the xylene mass reduction rate is related to the rice tsubo to some extent, so
At 280 g / m ² , xylene reduction rate of 60% or more
At 0 to 250 g / m ² , it is practical to set the xylene reduction rate to 70% or more.

In the corrugated board liner of the present invention, in a layer having a thickness from the bonding surface to 1/3 or less of the total thickness, J
The water retention of the pulp specified by APAN-TAPPI No. 26 is 125% or less, and the liner is sufficiently impregnated with xylene, and the mass reduction rate of xylene when heated at 120 ° C. for 10 seconds from the surface is 60%. In the case of the above, both effects are overlapped and the initial adhesiveness is further improved. Most preferably, the water retention is 120% or less and the xylene reduction rate is 70% or more.

As described above, it is important to reduce the water retention of the pulp of the laminating surface layer, but when the water retention is lowered by the above-mentioned various formulations, the wetting of the aqueous starch paste on the paper surface becomes worse. , There is also the possibility of reducing the adhesive strength. In that case, it is effective to apply a corona discharge treatment to the paper surface at any time before bonding.

[0023]

EXAMPLES The present invention will be described in more detail below with reference to examples. The water retention, dryness, and initial adhesiveness of various liners were measured and evaluated as follows. In addition,% shown below shows mass%.

<Measurement Method of Water Retention of Pulp> The water retention of pulp is obtained by peeling off a layer having a thickness up to 1/3 of the whole thickness from the bonding surface, disaggregating with a disintegrator, and then performing JA
It was measured according to PAN-TAPPI No. 26.

<Measurement Method of Xylene Mass Reduction Rate> The mass reduction rate of xylene when the liner was sufficiently impregnated and heated from the surface at 120 ° C. for 10 seconds was measured as follows. The liner is cut into a size of 100 × 70 mm, the mass is measured, and the liner is immersed in xylene. After sufficient immersion, wipe off the xylene on the surface and measure the mass. Immediately thereafter, a hot plate heated to 120 ° C. is set so that the front surface corresponds to the hot plate, and a weight is placed so that xylene is also evaporated from the back surface. After 10 seconds, the mass is measured and the mass reduction rate of xylene is calculated.

When the liner and the single-sided corrugated board are attached,
A double face tester (made by Sakuma Iron Works) having a width of 300 mm and a hot plate length of 600 mm was used. Hot plate temperature 180
C., and the laminating speed was 4.4 to 11.0 m / min.

The adhesive paste is raw starch (corn starch: made by Oji Corn Starch) for the main portion, processed starch (OHP-C153: made by Oji Corn Starch) for the carrier portion, caustic soda (sodium hydroxide: Wako Pure Chemical Industries, Ltd.). Made)
And borax (sodium tetraborate decahydrate: manufactured by Wako Pure Chemical Industries, Ltd.)
Was used. The carrier part uses processed starch in warm water (about 60
℃) and add a solution of caustic soda to prepare. The main part is made by dissolving raw starch in water and adding borax. The main part and the carrier part were combined to form a bonding paste. 3 parts of water to 100 parts by weight of starch (sum of raw starch and modified starch)
00 parts by mass, 2.2 parts by mass of caustic soda, and 2 parts by mass of borax were added.

The core raw paper used had a basis weight of 200 g / m ² . For the evaluation of the initial adhesion, a corrugated cardboard sheet that has come out of the cooling zone after the bonding is subjected to a 180 ° peeling test by three skilled testers, and ◎ is good, ○ is slightly inferior but practically no problem, The bad case was marked with x.

<Example 1> 100% NUKP pulp was beaten to make paper normally without adding chemicals, and further 120
The mixture was heat-treated at ℃ for 24 hours to obtain keratinized waste paper pulp. Anionic polyacrylamide (Polystron 117: Arakawa Chemical Co., Ltd.) 0.4% and amphoteric polyacrylamide (Polystron 480: Arakawa Chemical Co., Ltd.) 0.2% were added to the waste paper pulp to prepare a first layer (bonding surface). The waste paper pulp of the side layer) was used. Next, anionic polyacrylamide (Polystron 117: Arakawa Chemical Co., Ltd.) was added to NUKP with a freeness of 450 cc.
0.4%, amphoteric polyacrylamide (Polystron 48
0: Arakawa Chemical Co., Ltd.) 0.2% was added to the second layer of NUKP.
It was pulp. The waste paper pulp layer of 85 g / m ² and the NUKP pulp layer of 165 g / m ² are double-layered to have a basis weight of 250 g / m ^2.
A liner was prepared by ordinary paper making so that the density was m ² and the density was 0.86 g / cm ³ . The specific burst strength of this liner is 2.78.
(KPa · m ² / g).

<Example 2> In the same manner as in Example 1, keratinized waste paper pulp was obtained. Beat NUKP, NUKP 15%
And 85% of the waste paper pulp are mixed, and anionic polyacrylamide (Polystron 117: Arakawa Chemical Co., Ltd.) 0.4
%, Amphoteric polyacrylamide (Polystron 1231
N: Arakawa Chemical Co., Ltd.) 0.2% is added, and the basis weight is 280 g /
A liner was prepared by ordinary paper making so that the density was m ² and the density was 0.81 g / cm ³ . The specific burst strength of this liner is 2.72.
(KPa · m ² / g).

<Example 3> In the same manner as in Example 1, keratinized waste paper pulp was obtained. Beat NUKP, NUKP 35%
Anionic polyacrylamide (Polystron 117: Arakawa Chemical Co., Ltd.) 0.4
%, Amphoteric polyacrylamide (Polystron 1231
N: Arakawa Chemical Co., Ltd.) 0.2% is added, and the basis weight is 280 g /
m ^2, so that the density of 0.88 g / cm ^3, to obtain a liner Papermaking normal. The specific burst strength of this liner is 2.6.
It was 9 (kPa · m ² / g).

<Example 4> In Example 1, instead of keratinized waste paper pulp, a mixture of 80% by mass of commercially available corrugated cardboard waste paper and 20% by mass of water-resistant corrugated cardboard waste paper pulp was used. Similarly, basis weight 250g /
A liner having m ² and a density of 0.88 g / cm ³ was obtained. The specific burst strength of this liner was 2.66 (kPa · m ² / g).

<Comparative Example 1> Using a commercially available class A liner (manufactured by Warehauser Co., Ltd.) having a surface area of 280 g / m ² , the bonding and evaluation were carried out in the same manner as in Examples. The specific burst strength of this liner was 2.73 (kPa · m ² / g).

<Comparative Example 2> Using a commercially available A-class liner of 275 g / m ² of tsubo, Kit Liner (manufactured by Enso-Yukaron Co., Ltd.), lamination and evaluation were carried out in the same manner as in Example. The specific burst strength of this liner was 2.74 (kPa · m ² / g).

<Comparative Example 3> Using a commercially available class A liner, NRK280 (manufactured by Oji Paper Co., Ltd.) having a surface area of 280 g / m ² , the lamination and evaluation were carried out in the same manner as in the example. The specific burst strength of this liner was 2.76 (kPa · m ² / g).

Table 1 shows the physical property values of various liners and the results of initial adhesion evaluation.

[0037]

[Table 1]

[0038]

INDUSTRIAL APPLICABILITY The liner specified in the present invention can obtain a corrugated board sheet having good initial adhesion even if the laminating speed is increased without coating or adding chemicals. Is huge in terms of industry, operation and cost.

Claims (4)

[Claims] 1. The specific burst strength specified by JIS P-8131 is 2.65 (kPa · m ² / g) or more, and the thickness from the bonding surface to 1/3 of the total thickness. In layers, JAPAN
N-TAPPI No. A corrugated liner characterized in that the water retention of the pulp specified by 26 is 125% or less. 2. The specific rupture strength specified by JIS P-8131 is 2.65 (kPa · m ² / g) or more, and the xylene mass reduction rate by the following test method is 60% or more. A liner for corrugated board. Note: Test method A liner with a size of 70 cm ² is used as a sample, and the mass is measured. Then, the sample is thoroughly soaked in xylene, and the surface is lightly wiped to measure the mass. Immediately, place the sample on a metal plate heated to 120 ° C so that one side of the sample adheres to the metal plate,
Gently press on the top of a single-faced cardboard core with the same size, 1
The mass when heated for 0 seconds is measured. The mass of xylene evaporated in this 10 seconds is divided by the mass of xylene that has soaked into the liner to obtain the xylene mass reduction rate. 3. The corrugated liner according to claim 2, wherein the basis weight of the rice is 250 g / m ² or less, and the reduction rate of xylene is 70% or more. 4. The specific rupture strength specified in JIS P-8131 is 2.65 (kPa · m ² / g) or more, and the thickness from the pasting surface to 1/3 of the total thickness. In layers, JAPAN
N-TAPPI No. The liner for corrugated board according to any one of claims 2 to 3, wherein the water retention of the pulp specified by 26 is 125% or less.