JP2003003138A - Adhesive for adhering cardboard box - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive adhesive for bonding cardboxes capable of expressing strong adhesion, having excellent high speed bonding properties in the case when the amount of heat required for gelatinization is insufficient in a high speed bonding of cardboxes, e.g. even in the case when the adhesive is used in a high speed corrugator. SOLUTION: This adhesive for bonding cardboxes is obtained by solely using modified alkali treated starch improved in gelatinization properties of starch by making 0.5-20 wt.% alkali ingredient ununiformly adhered or absorbed to starch by dry process or the like or mixed with raw starch as a main starch.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corrugated board adhesive used for adhering a core and a liner of a corrugated board. More specifically, the present invention relates to an adhesive for corrugated board bonding which uses starch having improved gelatinization property as an ungelatinized starch constituting main starch in starch paste and which has excellent high-speed bonding suitability. In particular, the improved gelatinization property described here means that starch which has a time width in gelatinization expression during heating is reacted so that the starch reacts continuously even at a low temperature and continuously reacts as the temperature rises. It refers to the gelatinization property.

[0002]

2. Description of the Related Art Starch paste is often used as an adhesive agent for bonding corrugated cardboard from the viewpoint of cost. The adhesive for corrugated board bonding using starch is generally produced from water, gelatinized starch called carrier starch, non-gelatinized starch called main starch, alkaline component and, if necessary, boron compound. In the corrugated board manufacturing process,
The main starch in the adhesive is gelatinized by the heat applied through the liner base paper, and the adhesive strength is developed.

With the recent increase in size and speed of corrugators for corrugated board production, the amount of heat that the adhesive can receive from the corrugators tends to decrease. Therefore, in a corrugator that is bonded at a high speed, the main starch in the adhesive cannot obtain a sufficient amount of heat necessary for gelatinization, and the starch cannot express a sufficient adhesive force. Therefore, development of an adhesive having excellent suitability for high-speed laminating, that is, an adhesive having excellent suitability for laminating at high speed has been desired.

Conventionally, in the bonding suitability of an adhesive for corrugated cardboard, the physical property value of the gelatinization temperature is considered important, and the gelatinizing action of the main starch is a major factor that determines the bonding suitability of the adhesive. Has been considered. That is, it is generally considered that the main starch is preferably a starch that exhibits a gelatinization behavior such that it rapidly swells and gelatinizes when heated and expresses viscosity all at once.

Japanese Patent Publication No. 61-11982 discloses a method in which esterified tapioca starch having a reduced gelatinization temperature is used as a main starch, and the starch is rapidly gelatinized at a low temperature to improve high-speed laminating suitability. Have been described. However, the processing method described here is generally called a wet method, and the processed starch (modified starch) prepared by this method requires a high degree of processing in order to lower the gelatinization temperature, and the price is low. It gets expensive. If such a modified starch by the wet method is used as the main starch that occupies 80% or more of the starch used, the cost will be greatly increased, so it is rarely used in reality, and cheap raw corn starch etc. Is currently widely used. That is,
At present, no inexpensive adhesive has been obtained which has satisfactory high-speed laminating suitability for use in a high-speed corrugator in which a sufficient amount of heat cannot be obtained, and which is inexpensive. Against this background,
It is required to provide an inexpensive adhesive having excellent suitability for high-speed laminating.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a sufficient adhesive force even when the amount of heat required for gelatinization is insufficient for sticking corrugated board at high speed, for example, when used in a high speed corrugator. To provide an adhesive for corrugated board, which exhibits excellent high-speed bonding suitability and is inexpensive.

[0007]

[Means for Solving the Problems] The present inventors have proposed that by using an alkali-treated starch having an improved gelatinization property as a main starch by adhering or adsorbing an alkali component nonuniformly by a dry method or the like. The inventors have found that the problems can be solved and have completed the present invention.

That is, the present invention includes the following inventions. (1) An adhesive for corrugated board, which is obtained by using, as a main starch, an alkali-treated starch obtained by non-uniformly adhering or adsorbing 0.5 to 20% by weight of an alkali component to starch. (2) 0.5 to 20% by weight of starch by dry method
An adhesive for corrugated board sticking, which is obtained by using, as a main starch, an alkali-treated starch obtained by adhering or adsorbing the alkali component of. (3) Corrugated cardboard obtained by using as a main starch a starch mixture containing a raw starch and an alkali-treated starch obtained by non-uniformly adhering or adsorbing 0.5 to 20% by weight of an alkali component to starch Adhesive. (4) 0.5 to 20% by weight based on starch by dry method
An adhesive for corrugated board, which is obtained by using, as a main starch, a starch mixture containing an alkali-treated starch obtained by adhering or adsorbing the alkaline component of 1. and a raw starch. (5) The weight ratio of the alkali-treated starch and the raw starch is 1 to
The adhesive for corrugated board bonding according to (3) or (4) above, which is 99: 99-1. (6) The main starch was 20 BU (Brabender Unit) in the measurement method using alkali Brabender amylograph.
The adhesive for corrugated board bonding according to any one of (1) to (5), which has a physical property value of 20 minutes or less in arrival time.

In the present invention, a predetermined amount of alkali component is non-uniformly adhered to or adsorbed to starch by a dry method or the like, and the starch chains are firmly bound in the starch granules.
By unevenly cutting or relaxing the hydrogen bonds in the part forming the starch granules, an alkali-treated starch with improved gelatinizing property is produced, which is used alone or mixed with raw starch,
This is used as the main starch. In the present specification, nonuniformly adhering or adsorbing an alkaline component means adhering or adsorbing an alkaline component only to a part of starch and / or at a partially nonuniform concentration.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The adhesive for corrugated board of the present invention, for example, by using a dry method, non-uniformly adhering or adsorbing an alkali component, modified alkali-treated starch to improve gelatinization property, alone or as a raw starch It is mixed and prepared as main starch, and is mainly used for bonding the core and the liner.

In the present specification, the dry method is a heterogeneous reaction system in which a drug is added to starch which is a powder by means such as spraying, or a powdery drug is directly mixed with starch. On the other hand, the wet method means that the starch is dispersed in a solvent to add a drug to a slurry system,
It means a reaction method for producing a uniform reaction system.

Up to now, it has been considered necessary for the main starch to have a uniform gelatinizing property and to be gelatinized all at once by heating in order to obtain excellent high-speed laminating suitability. The present inventors, as a result of earnest research, are different from the conventional way of thinking,
By intentionally imparting non-uniform gelatinization characteristics to starch, we succeeded in improving the gelatinization property. Specifically, it is the establishment of a method for shifting the temperature at which gelatinization of starch starts to a low temperature side so that gelatinization during heating has a time range. The present inventors have found that the use of such a starch as the main starch makes it possible to obtain an adhesive having a significantly improved suitability for high-speed bonding, as compared with a conventional adhesive. It is considered that the time required for starch having non-uniform gelatinization properties from the start of gelatinization to the completion of gelatinization is extended,
By replacing part or all of the starch with starch subjected to the above-mentioned non-uniformization treatment, the gelatinization start temperature shifts to the low temperature side, and even in the low temperature range, viscosity is developed in some starch granules, Adhesive strength is developed in the stage before the initial adhesive strength is developed. It is presumed that, unlike conventional adhesives, this action makes it possible to perform bonding even in a heat disadvantageous situation. Here, the initial adhesive strength refers to the adhesive strength at the stage when the drying of the glue is not completely completed, as compared to the normal adhesive strength where the glue is dried and shows stable adhesive strength. Since the corrugated board is subjected to various processes such as cutting before the progress of the step, the initial adhesive strength and the strength of the adhesive strength at the preceding stage are particularly important in the corrugated board bonding adhesive. As a means for preparing a non-uniformized starch having a time width for gelatinization expression during heating, it was concluded that a method of unevenly adhering or adsorbing an alkaline component to starch is effective. The present invention has been completed.

The alkali component attached or adsorbed to the starch used in the present invention is not particularly limited, and any alkali component attached or adsorbed to the starch and capable of cutting or relaxing hydrogen bonds in the starch granules is used. Any alkali component may be used. Examples include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and the like;
Alkaline earth metal hydroxides, such as calcium hydroxide, magnesium hydroxide and the like, but in terms of cost,
Sodium hydroxide is preferred from the viewpoint of reactivity.

In the present invention, it is necessary that the alkali component is non-uniformly adhered to or adsorbed to the starch from the viewpoint that the gelatinization during heating has a time range. As a means for that, a dry method can be used. Examples of the dry method include a method in which a powdery starch is sprayed with an aqueous alkali solution having a predetermined concentration, or a method in which a powdery alkaline component is directly mixed with the starch. When spraying an aqueous solution of an alkaline component, the concentration of the alkaline aqueous solution is 5% by weight.
The above is preferable. Concentration of alkaline aqueous solution is 5
If it is less than wt%, the action of breaking or relaxing the hydrogen bonds of the starch granules in contact with the alkali component is significantly reduced.
In the dry method, heating or cooling may be performed in order to control the degree to which the alkaline component in the starch particles attached or adsorbed to the starch breaks or relaxes hydrogen bonds.

The amount of the alkaline component to be adhered or adsorbed needs to be 0.5 to 20% by weight, and preferably 1 to 10% by weight, based on the starch. When the amount of the alkaline component is less than 0.5% by weight, the gelatinization property of the obtained starch is not much different from that of the starch before the treatment, and the high-speed laminating suitability cannot be improved. In addition, the effect of modifying the gelatinization property by the alkaline component reaches almost the upper limit when the amount of the alkaline component that adheres or adsorbs reaches about 20% by weight with respect to the starch, so that from the economical point of view, the effect of adhering or absorbing The amount of the alkali component to be caused is 20% by weight or less based on the starch.

On the other hand, the starch used as a raw material for preparing the alkali-treated starch may be any starch commonly used in adhesives for corrugated board, and is not particularly limited.
For example, cornstarch, high amylose cornstarch, waxy cornstarch, tapioca starch, sweet potato starch, potato starch, natural starch such as wheat starch, rice starch, sago starch, etherification by esterification, esterification by reacting them by a wet method or a dry method, Cationized, oxidized or acid treated processed starch (modified starch) or a mixture of these starches can be used.

From the viewpoint of obtaining a sufficient high-speed laminating suitability, the main starch having a modified gelatinization property preferably has an arrival time of 20 BU of 20 minutes or less in the alkali Brabender amylograph method. Here, the alkali Brabender amylograph method is a method of measuring the gelatinization property of starch dispersed in an alkaline aqueous solution.

The initial adhesive strength can be evaluated by measuring the initial adhesive strength. The initial adhesive strength is as follows: Apply 5g / m ² of dry-drying adhesive for corrugated board to the single-sided corrugated board, press it against the liner with a hot plate, and immediately peel off the liner and single-sided corrugated board. Can be measured by The higher the initial adhesive strength of the adhesive for corrugated board bonding of the present invention, the better the high-speed bonding suitability.

In the present invention, a starch mixture containing the alkali-treated starch and raw starch may be used as the main starch. The main starch composed of the starch mixture preferably has an arrival time of 20 BU of 20 minutes or less in the alkali Brabender amylograph method from the viewpoint of obtaining sufficient high-speed laminating suitability. Here, the alkali Brabender amylograph method is a method of measuring the gelatinization property of starch dispersed in an alkaline aqueous solution.

The raw starch mixed with the alkali-treated starch may be any starch commonly used in adhesives for corrugated cardboard, and is not particularly limited.
Natural starch such as corn starch, high amylose corn starch, waxy corn starch, tapioca starch, sweet potato starch, potato starch, wheat starch, rice starch, sago starch, etc., and etherification by reacting them by a wet method or a dry method,
Esterified, cationized, oxidized or acid-treated processed starch (modified starch), or a mixture of these starches can be used. From the viewpoint of economy, it is preferable to use raw natural starch. The weight ratio of the alkali-treated starch and the raw starch is 1 from the viewpoint of obtaining sufficient high-speed laminating suitability.
˜99: 99-1 is preferable, and 3-15: 97-85 is more preferable from the viewpoint of performance and economy.

The alkali-treated starch and the raw starch can be mixed by mixing the starches with each other or by dispersing the starch in water and mixing them in a dispersion liquid. Good. Regarding the mixing timing, there are a method of mixing at the time of making glue and a method of mixing at the time before making glue, but either method may be used.

It is preferable to add a boron compound such as borax, boric acid or sodium metaborate to the adhesive for corrugated board bonding of the present invention so that the starch exhibits tackiness (adhesion) when gelatinized. . The method for producing the adhesive for corrugated board of the present invention is not particularly limited, but, for example, a commonly used two-tank or one-tank stain hole method, a premix method, or a no-carrier method can be used. .

The corrugated board bonding adhesive of the present invention is an adhesive having improved high-speed bonding suitability, in which the gelatinization property of the main starch is modified. The mechanism of imparting such properties is not known in detail, but when the alkali component is attached or adsorbed, only a part of the starch granules in contact with the alkali component is converted into hydroxide ion contained in the alkali component. It is presumed that the hydrogen bond is cleaved or relaxed by the action to cause swelling or rupture, which causes a time width in gelatinization expression during heating, and thus a starch having non-uniform gelatinization properties is obtained. It

Regarding the method for improving the gelatinization property of starch by using an alkali component, a method of immersing the starch in an alkaline aqueous solution is found in JP-A-9-194501. In the present invention, the starch is Since the starch is soaked in an alkaline aqueous solution, the gelatinization properties of the obtained starch will be uniform, and the alkaline aqueous solution used is a low-concentration alkaline aqueous solution to prevent the starch from completely gelatinizing. Therefore, the effect of cleaving or relaxing the hydrogen bond of starch is small, and the same gelatinizing property as that of the present invention cannot be obtained. Therefore, it is difficult to prepare an adhesive having excellent high-speed laminating suitability.

[0025]

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. Further, in the following Examples and Comparative Examples, the measurement of the 20BU arrival time, the measurement of Ford cup viscosity, the measurement of B-type viscosity, the measurement of gelatinization temperature, and the measurement of the initial adhesive strength in the alkaline Brabender amylograph method were carried out as follows. Made by way. 20B in alkaline Brabender amylograph method
U arrival time: measured using a Brabender amylograph. That is, pure water is added to 125 g of starch until the total amount becomes 300 g, and the starch is dispersed. To this, 25% by weight
A solution obtained by mixing 10 ml of the aqueous sodium hydroxide solution and 180 ml of pure water is slowly added. After transferring the obtained starch dispersion liquid to a Brabender amylograph container, pure water is added to adjust the total amount to 500 g, and the Brabender amylograph is started. The Brabender amylograph is programmed to heat at a rate of 1.5 ° C / min until the liquid temperature reaches 44 ° C, and when it reaches 44 ° C, hold the temperature at 44 ° C. The time until the viscosity reaches 20 BU is measured. In addition, in this alkaline Brabender amylograph method, the cartridge 700
cm-g is used and the rotation speed is 100 rpm. Ford cup viscosity: Measured with a Ford cup (water 10 seconds) manufactured by Toyo Tester Co., Ltd. Type B viscosity: Rotational viscometer manufactured by Tokyo Keiki Co., Ltd. (type: B
M type) at 60 rpm. Gelatinization temperature: measured using a Brabender amylograph. That is, take 500g of sample in a Brabender cup,
The measurement was carried out under the conditions of a cartridge 750 cm-g, a rotation speed of 100 rpm, and a temperature rise of 1.5 ° C./min. The temperature at which the temperature increased by 500 BU from the minimum viscosity during measurement was defined as the gelatinization temperature. Initial adhesive strength: 50 mm x 85 mm single-sided corrugated board (base paper composition: Prince: NRK-280 g / Hokuyo: MM-
180 g) is coated with an absolutely dry adhesive of 5 g / m ² for corrugated cardboard and set in a pin tester equipped with a load cell. A liner (Oji: NRK-280g) is placed on it, and pressure-bonded for 10 seconds by a hot plate (120 ° C.) having a weight of 1.5 kg. Immediately after pressure bonding, the liner and the single-sided corrugated board were peeled off, and the strength at that time was measured as an initial adhesive strength by a load cell.

(Comparative Example 1) 630 g of water heated to 40 ° C. was placed in a 3 L stainless steel jug, and an agitator Robomix manufactured by Tokushu Kiki Kogyo Co., Ltd. was used under the condition of 5500 rpm to obtain unprocessed corn starch ( Carrier starch) 62
g was dispersed. To this, 40 g of a 25% by weight sodium hydroxide aqueous solution was added and stirred for 15 minutes to prepare a carrier starch paste. This carrier starch paste is mixed with water at 40 ° C 84
0 g, unprocessed cornstarch (main starch) 438 g whose arrival time to 20 BU was previously measured by the alkali Brabender amylograph method, and 10 g of borax were continuously added, followed by stirring for 15 minutes and one tank stain hole method To obtain an adhesive. The Ford cup viscosity, B-type viscosity, gelatinization temperature and initial adhesive strength of the obtained adhesive were measured. The measurement results are shown in Table 1.

(Example 1) Raw corn starch 7 kg
In a Lodige mixer, and while stirring well, add 3% of a 25% by weight aqueous sodium hydroxide solution so that 1.25% by weight of the alkali component adheres to or adsorbs to the starch.
50 g (87.5 g as an alkaline component) was sprayed. After spraying, the starch was dried at 70 ° C. for 30 minutes, and the arrival time of 20BU was measured by the alkali Brabender amylograph method. Next, using this alkali-treated starch as the main starch, an adhesive for corrugated board bonding was prepared in the same manner as in Comparative Example 1, and the Ford cup viscosity, B-type viscosity, gelatinization temperature and initial adhesive strength of the adhesive were measured. did. The measurement results are shown in Table 1.

(Example 2) Spraying was carried out so that 7.14% by weight of an alkaline component was adhered to or adsorbed on starch.
The amount of the sodium hydroxide aqueous solution with a concentration by weight of 2000 g
An adhesive for corrugated board bonding was prepared and the Ford cup viscosity, B-type viscosity, gelatinization temperature and initial adhesive strength of the adhesive were measured by the same method as in Example 1 except that the amount of the alkali component was 500 g. did. The measurement results are shown in Table 1.

(Example 3) Raw corn starch 7k
87.5g of granular sodium hydroxide (1.25g for starch)
Wt%) was added. Next, this starch is dried at 70 ° C. for 30 minutes, and 20 BU is obtained by the alkali Brabender amylograph method.
The arrival time was measured. Using this alkali-treated starch as the main starch, a corrugated board bonding adhesive was prepared in the same manner as in Comparative Example 1, and the Ford cup viscosity, B-type viscosity, gelatinization temperature and initial adhesive strength of the adhesive were measured. The measurement results are shown in Table 1.

(Comparative Example 2) Spraying was carried out so that 0.16% by weight of an alkaline component adhered to or adsorbed on starch 25
An adhesive for corrugated board bonding was prepared in the same manner as in Example 1 except that the amount of the aqueous solution of sodium hydroxide having a concentration by weight of 44 g (11 g as an alkaline component) was prepared. The mold viscosity, gelatinization temperature and initial adhesive strength were measured. The measurement results are shown in Table 1.

Example 4 10% by weight of the alkali-treated starch prepared in Example 1 and 90% by weight of unprocessed corn starch were mixed, and the mixture was mixed with an alkaline Brabender amylograph method to obtain 2%.
The 0BU arrival time was measured. Next, using this starch mixture as a main starch, an adhesive for corrugated board bonding was prepared in the same manner as in Comparative Example 1, and the Ford cup viscosity, B-type viscosity, gelatinization temperature and initial adhesive strength of the adhesive were measured. . The measurement results are shown in Table 2.

(Example 5) The same operation as in Example 4 was performed except that the mixing ratio of the alkali-treated starch and the unprocessed corn starch was 5:95 by weight, and the main starch was subjected to the alkali Brabender amylograph method. The arrival time of 20 BU was measured, and the Ford cup viscosity, B-type viscosity, gelatinization temperature and initial adhesive strength of the adhesive prepared using this main starch were measured. The measurement results are shown in Table 2.

(Example 6) 7 kg of raw tapioca starch
In a Lodige mixer, and while stirring well, add 6 wt% aqueous sodium hydroxide solution with a concentration of 15 wt% so that 1.37 wt% of the alkaline component adheres to or adsorbs to the starch.
After spraying 40 g (96 g as an alkali component), cation master C-60 (manufactured by Yokkaichi Gosei Co., Ltd.) 390 g
The starch was cationized by subsequent spraying to prepare dry cationized tapioca starch with non-uniform gelatinizing properties. After spraying, dry the starch for 30 minutes at 70 ° C,
20BU arrival time was measured by the alkali Brabender amylograph method. Using this alkali-treated cationized starch as the main starch, a corrugated board bonding adhesive was prepared in the same manner as in Comparative Example 1. Ford cup viscosity of adhesive, B type viscosity, gelatinization temperature and initial adhesive strength are measured,
The measurement results are shown in Table 3.

Example 7 5% by weight of the alkali-treated cationized starch of Example 6 and 95% by weight of unprocessed corn starch were mixed, and the arrival time of 20 BU was measured by the alkaline Brabender amylograph method. Next, using this starch mixture as the main starch, an adhesive for corrugated board bonding was prepared in the same manner as in Comparative Example 1, and the Ford cup viscosity, B-type viscosity, gelatinization temperature and initial adhesive strength of the adhesive were measured. did. The measurement results are shown in Table 3.

(Example 8) Starch mixed with raw corn starch was reacted by a dry method with cationized tapioca starch having a non-uniform gelatinizing property (trade name Pillar 4; manufactured by Oji Trading Co., Ltd.). Example 7 except that
Perform the same operation as above to measure the arrival time of 20 BU in the alkaline Brabender amylograph method of main starch,
The Ford cup viscosity, B-type viscosity, gelatinization temperature, and initial adhesive strength of the adhesive prepared using this main starch were measured. The measurement results are shown in Table 3.

(Comparative Example 3) Geltron 12 (manufactured by General Starch Co., Ltd.), which is a cationized tapioca starch having a uniform gelatinizing property and subjected to alkali treatment by a wet method, and raw corn starch were mixed to obtain a main starch. Except
The same operation as in Example 7 was carried out to measure the arrival time of 20BU of the main starch in the alkali Brabender amylograph method, and the Ford cup viscosity, B-type viscosity, gelatinization temperature, and gelatinization temperature of the adhesive prepared using this main starch were measured. The initial adhesive strength was measured. The measurement results are shown in Table 3.

Comparative Example 4 The same as Example 7 except that the main starch was prepared by mixing acetylated tapioca starch having a uniform gelatinizing property and treated with an alkali by a wet method with unprocessed corn starch. The operation was performed, and the arrival time of 20BU was measured by the alkali Brabender amylograph method of the main starch, and the Ford cup viscosity, B-type viscosity, gelatinization temperature and initial adhesive strength of the adhesive prepared using this main starch were measured. . The measurement results are shown in Table 3.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

[Table 3] From Tables 1 to 3, since the adhesive for corrugated board bonding of the present invention has a high initial adhesive force which is a factor that determines the bonding speed,
It can be seen that it has excellent high-speed laminating suitability.

[0041]

EFFECTS OF THE INVENTION According to the present invention, a starch having a non-uniform gelatinizing property is prepared. By using this starch as the main starch of the adhesive for corrugated board bonding, an adhesive excellent in high-speed bonding is obtained. be able to.

Claims (6)

[Claims] 1. An adhesive for corrugated board, which is obtained by using, as a main starch, an alkali-treated starch obtained by non-uniformly adhering or adsorbing an alkali component of 0.5 to 20% by weight to a starch. 2. 0.5 to 2 for starch by a dry method.
An adhesive for corrugated board, which is obtained by using, as a main starch, an alkali-treated starch obtained by adhering or adsorbing 0% by weight of an alkaline component. 3. A corrugated board obtained by using, as a main starch, a starch mixture containing a raw starch and an alkali-treated starch obtained by non-uniformly adhering or adsorbing 0.5 to 20% by weight of an alkali component to the starch. Adhesive for laminating. 4. The dry method is used to add 0.5 to 2 to starch.
An adhesive for corrugated board bonding, which is obtained by using, as a main starch, a starch mixture containing an alkali-treated starch obtained by adhering or adsorbing 0% by weight of an alkaline component and raw starch. 5. The adhesive for corrugated board bonding according to claim 3, wherein the weight ratio of the alkali-treated starch and the raw starch is 1 to 99:99 to 1. 6. The adhesive for corrugated board bonding according to claim 1, wherein the main starch has a physical property value of 20 BU arrival time of 20 minutes or less in a measuring method using an alkali Brabender amylograph. .