JP2002226810A - Adhesive for high-temperature, high-speed type corrugated cardboard - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive for high-temperature, high-speed type corrugated cardboard, which is improved for a high-speed corrugator. SOLUTION: This adhesive for a high-temperature, high-speed corrugated cardboard is characterized in that at least two kinds of starches which have different amylogram maximum viscosities and gelatinization starting temperatures and contain amylose (starch having a high viscosity of >=400 BU amylogram maximum viscosity at 4% starch concentration/<=85 deg.C low gelatinization starting temperature is starch Y for short and starch having a low viscosity of 120-20 BU amylogram maximum viscosity at 4% starch concentration/>=90 deg.C high gelatinization starting temperature is starch Z for short) are mixed in the ratio of the starch Y:the starch Z of 3:97 to 25:75.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corrugated cardboard adhesive improved for a high-speed corrugator whose speed has been increasingly increased in recent years.

[0002]

2. Description of the Related Art In recent years, corrugators, which are machineries for manufacturing corrugated cardboard, have been increasing in size and tending to operate at higher speeds. Therefore, development of an adhesive for high-speed corrugated board corresponding to such a high-speed corrugator is an important issue. As a method of preparing an adhesive for cardboard, conventionally,
Various methods have been developed and put into practical use, and typical examples thereof include a Steinhole method (hereinafter abbreviated as an SH method), a one-tank method, and a no-carrier method (hereinafter abbreviated as an NC method). .

In the SH method, a starch (carrier portion) completely gelatinized by alkali and heat and an aqueous suspension (main portion) of ungelatinized starch particles are prepared in advance. The viscosity of the adhesive after mixing both mainly depends on the carrier part. The viscosity after heating is large and contributes to the development of the initial adhesive strength. The one-tank method is a method in which a carrier part is prepared in the same manner as in the SH method, and then the main part is charged into the same tank, mixed, and used as an adhesive. That is, although there is no change in the preparation of the carrier portion and the main portion as in the SH method, the number of glue making tanks is reduced and the operability is improved. The NC method is a suspension in which starch is completely suspended in water and then carefully swelled to a predetermined viscosity so that starch particles are not gelatinized by alkali addition. Rather than depending on the viscosity of the size liquid as in the SH method, the viscosity is expressed by swollen starch particles. Each of the cardboard adhesives prepared by the above method is applied to paperboard by a corrugator, and is heated and dried to bond the cardboard.

As an example of the conventional method, Japanese Patent Publication No. 59-285
Nos. 94, 59-28595, 59-2859
No. 6 are mentioned. In these, the following properties required for starch as the initial adhesive strength of the cardboard adhesive are given. In high-speed corrugators, the adhesive is applied to the top of corrugated paperboard (flute) and then pressed onto flat paperboard (liner). To increase the viscosity, it is necessary to increase the viscosity of the applied starch suspension at a high speed, and it is important that the swelling and gelatinization of the suspended starch particles be fast. Therefore, a starch having a high swelling speed and a large swelling particle size, that is, a starch having a high maximum viscosity, that is, a starch having a high swelling rate is preferred, so that swelling gelatinization starts at a low temperature, the gelatinization starting temperature is low, and the viscosity increases quickly, and the swelling gelatinization is started. Moreover,
Although it is described that esterified starch is preferable as a corrugated cardboard adhesive, the gelatinization start temperature and the maximum viscosity of starch greatly depend on the properties of raw starch. It is difficult to achieve gelatinization onset temperature and maximum viscosity. In addition, in the appropriate starch of gelatinization start temperature and maximum viscosity such as potato starch and various modified starch,
The use of one type of starch alone results in excessive gelatinization after completion of lamination, as described in Comparative Examples herein.
As a result, the normal adhesive strength decreases.

In Japanese Patent Application Laid-Open No. 58-173172, esterified tapioca starch, in particular, an ester group is added in an amount of 0.01 to 0.1 per glucose unit based on the same idea as described above.
Although the use of a substituted product is described, it is difficult to say that the use of one type of starch alone is industrially sufficient as a corrugated cardboard adhesive, as described above.

[0006] In JP-A-59-23774, in the SH method, a low gelatinization temperature starch is completely gelatinized with an alkali and used as a carrier part, and a high gelatinization temperature starch is used as a main part of a corrugated cardboard. Adhesives are described. Although starches having different gelatinization temperatures are used, starch having a low gelatinization temperature is not in a particle state and has already been gelatinized, and does not contribute to high-speed thickening or high-viscosity development due to swelling. The main part has a composition of starch alone having a high gelatinization temperature. Therefore, no contribution to the initial adhesive strength can be expected, and it is equivalent to the use of corn starch alone, only the workability in the preparation of the carrier part is simply improved, and no industrial advantage is recognized as a cardboard adhesive. . All of the above methods have attempted to improve corrugated cardboard adhesives for large and high-speed corrugators in recent years, but none of them have been satisfactory in performance.

Therefore, Japanese Patent Application Laid-Open No. 2-281090 discloses an adhesive for cardboard made by a no-carrier method, wherein at least two kinds of starches having different maximum amyogram viscosities (high-viscosity starch is A starch and low-viscosity starch is B starch). Starch (abbreviated as starch) in the ratio of A starch / B starch; 3/7 to 9/1, water ratio 2 to 5 times, Ford cup viscosity 2
A high-speed, low-temperature heating type cardboard adhesive characterized by being prepared in the range of 0 to 50 seconds (30 ° C.) has been proposed.

At the time of the development of the adhesive for corrugated cardboard, there was a strong demand to achieve energy saving and quality improvement by low-temperature bonding at the same time as high speed, and attempts were made to reduce the temperature of the heating roll and the drying step of the corrugator. Therefore, also in the above publication, the bonding conditions in the laboratory were assumed to be the temperature and time appropriate for the actual machine, and the performance test of the bonding strength at 120-130 ° C. for 3 seconds, respectively, showed that the ratio of A starch / B starch was 3%. / 7 to 9/1, the best adhesive strength is obtained. In addition, good results have been obtained in tests on actual factory equipment using a starch adhesive in the above mixing ratio.

However, in recent years, as the speed has been further increased, the heating temperature has been gradually increased. If a high-viscosity starch having a low gelatinization start temperature is used, gelatinization will be excessive, and the workability will decrease due to the increase in the viscosity of the gelatin. And a decrease in the normal adhesive strength. Therefore, there has been a demand for a corrugated cardboard adhesive that satisfies the bonding speed and corrugated cardboard characteristics of recent high-temperature high-speed corrugators.

[0010]

SUMMARY OF THE INVENTION The present invention solves the problems of the conventional adhesive for cardboard as described above,
Regardless of the manufacturing method such as the H method, the one-tank method, and the NC method, the high viscosity / low gelatinization temperature starch swells uniformly and rapidly in all adhesives for corrugated cardboard, and exhibits high viscosity, that is, high initial adhesive strength. On the other hand, the viscosity at the time of gelatinization is designed to be in a controllable range, and at the same time, the viscosity at the time of gelatinization of the main component low viscosity / high gelatinization start temperature is controlled within an appropriate range. It is another object of the present invention to provide a high-temperature and high-speed corrugated cardboard adhesive which swells by heating on a corrugator but suppresses gelatinization, and improves the normal adhesive strength by remaining starch swelling particles. Things.
That is, an object of the present invention is to provide a corrugated cardboard adhesive that can be used at a high temperature and high speed of a corrugator.

[0011]

Various mechanisms have been discussed on the mechanism of the function of the adhesive for corrugated cardboard, but at present, it is limited to the range of experience and cannot be clearly explained. However, the main part of the SH method and the swollen starch of the NC method apply heat and pressure to apply an adhesive to the top of the flute, press the liner on the top of the flute, and gelatinize it to exert the adhesive force. It is generally accepted that this is a fully functional latent adhesive only after application. It is also known that the properties of a corrugated cardboard adhesive greatly depend on swelling and gelatinization of starch particles due to heating, and viscosity behavior. The relationship between the temperature and the viscosity of the aqueous starch suspension will be described later in detail.

[0012] In order to satisfy both the initial adhesive strength and the normal adhesive strength in laminating with a high-speed corrugator, it is difficult to achieve it by using one kind of starch alone. That is, it is preferable to mix at least two types of starch containing amylose and having different maximum amylogram viscosities and different gelatinization initiation temperatures in an appropriate ratio. However, almost no cardboard adhesives developed based on such a concept have been found, and only the cardboard adhesives disclosed in the above-mentioned JP-A-2-281090 have been proposed. However, as described above, this adhesive for corrugated cardboard is a low-temperature-gelatinized cardboard adhesive for the purpose of energy saving by low-temperature bonding, and has a different purpose from the high-temperature and high-speed cardboard adhesive of the present invention. Under high temperature heating conditions of a high-speed corrugator in recent years, there has been a problem that the initial adhesive strength and the normal adhesive strength are reduced due to excessive gelatinization.

[0013] The present inventors have determined the relationship between the initial adhesive strength and the normal adhesive strength, such as the paste viscosity at the time of sizing, the type and ratio of starch, and the gelatinization start temperature and the maximum viscosity, when designing adhesives for high-temperature corrugators. As a result of detailed examination from the viewpoint again, by mixing at least two types of starch having a maximum amylogram viscosity within a specific range and a gelatinization start temperature in a weight ratio within a specific range, both initial adhesive strength and normal adhesive strength are excellent. The present inventors have found that a high-temperature and high-speed adhesive for cardboard can be obtained, and have reached the present invention.

That is, the present invention relates to (a) a high-viscosity / low-gelatinization start temperature starch having a maximum amyogram viscosity of 400 BU or more at a starch concentration of 4% and a gelatinization start temperature of 85 ° C. or less (Y starch and Abbreviated), and (b) at least a low-viscosity / high-gelatinized onset temperature starch (abbreviated as Z starch) having a maximum amylogram viscosity of 120 to 20 BU at a starch concentration of 4% and having a gelatinization onset temperature of 90 ° C. or higher. It contains two types of starch, Y starch and Z starch both contain amylose,
The present invention relates to a high-temperature and high-speed corrugated cardboard adhesive characterized in that the weight ratio of starch: Z starch is in the range of 3:97 to 25:75.

Further, in order to preferably carry out the present invention, the Y starch is potato starch, sweet potato starch; their etherified starch, esterified starch, crosslinked starch and grafted starch; and a mixture of two or more thereof. Wherein the Z starch is selected from the group consisting of corn starch, wheat starch; their etherified starch, esterified starch, crosslinked starch and grafted starch; and a mixture of two or more thereof. Preferably, the weight ratio of starch: Z starch is in the range of 5:95 to 20:80, and the amylose content of the Y starch and Z starch is in the range of 20 to 30% by weight.

The relationship between the performance of the high-temperature and high-speed type cardboard adhesive of the present invention and the viscosity and the gelatinization start temperature will be described with reference to FIG. FIG. 1 is a schematic diagram showing an amyogram measured at a concentration of 4% by weight of one embodiment of the adhesive for high-temperature and high-speed corrugated cardboard according to the present invention, wherein a combination of potato starch and corn starch is used as the adhesive for high-temperature and high-speed corrugated cardboard. This is an example. The amylogram of potato starch also shows a schematic diagram schematically showing a change in the state of starch particles with an increase in temperature. The starch particles begin to swell with increasing temperature, but do not show viscosity while the starch particles are small and the viscosity curve is at the baseline. As the degree of swelling of the starch particles increases, the viscosity starts to rise, and the viscosity curve rises from the baseline and rises sharply. The highest viscosity is reached when the starch particles swell and become the largest, the temperature further rises and the starch particles collapse,
The viscosity has been suddenly reduced due to gelatinization. Potato starch is at least 20 ° C lower than the gelatinization start temperature of corn starch at 93 ° C.
Start gelatinization at ° C. Potato starch has a maximum viscosity of 1250B
When it reaches U, corn starch does not start gelatinizing,
This is a stage where no viscosity is exhibited. It is not believed that the viscosity of the corn starch contributes to the initial bond strength on the corrugator. Therefore, it is clear that the initial adhesive strength mainly depends on the viscosity of the potato starch thickened by swelling. On the other hand, after the adhesion with the corrugator is completed, the particles of the potato starch are almost completely disintegrated and gelatinized to form starch paste having poor cohesive strength. Therefore, the normal adhesive strength largely depends on the starch paste containing the ungelatinized swollen particles of corn starch, which is the main component.

However, as shown in JP-A-2-281090, the ratio of two types of starch A starch / B starch is 3 /
When mixed in the range of 7 to 9/1, in a recent high-temperature corrugator, the ratio of starch at a low gelatinization start temperature is too high, causing excessive gelatinization, resulting in a decrease in adhesive strength. ing. In addition, as the ratio of A starch increases, the viscosity increases greatly during paste making and paste preservation, and workability deteriorates. Therefore, the Y starch: Z starch ratio of the present invention is 3:97 to 25:
A mixture in the range of 75 is preferred.

In the case of etherified, esterified and grafted starch, the maximum amyogram viscosity is determined by the degree of substitution (D.
S .: number of substituents per glucose unit). In the case of cross-linked starch, the maximum viscosity increases slightly at a low degree of cross-linking, but further cross-linking tends to cause a significant decrease in the maximum viscosity and an increase in the gelatinization start temperature.
Therefore, it is necessary to appropriately select the degree of substitution.

The starch used in the present invention is required to contain amylose. When gluing a cardboard adhesive using starch containing almost no amylose,
Although the initial adhesive strength shows excellent performance comparable to potato starch or the like, the normal adhesive strength is insufficient. This fact is supported by the results of using a cardboard adhesive made of waxy corn starch, which is made of 99% amylopectin and contains almost no amylose, using Y starch as a comparative example. It can be concluded that the presence of amylose is indispensable for developing normal adhesive strength. The rationale is not clear, but it is thought to be due to the aging effect of the amylose molecule. The content of amylose in the starch is preferably about 20 to 30% by weight.

The present invention is characterized in that, of at least two types of starch having different maximum amyogram viscosities and gelatinization onset temperatures, excellent initial adhesive strength is exhibited by the swelling viscosity of the starch particles having a low gelatinization onset temperature. I have. Therefore,
The method of preparing the adhesive for corrugated cardboard is more effective in the NC method than in the SH method. In the SH method, since the initial adhesive strength largely depends on the carrier part, the effects of fast swelling and high viscosity, which are characteristics of starch having a low gelatinization start temperature, tend to be hardly exhibited. However, when the main portion is composed of two types of starch, an improvement in the initial adhesive strength is recognized as in the NC method due to the swelling viscosity of the starch particles having a low gelatinization start temperature.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The apparatus, technical terms and materials used in the above description and the following embodiments will be described in detail below. However, it is not limited to these.

(Amylogram) As a device for measuring and recording a change in viscosity of a starch suspension due to heating, an amylograph (manufactured by Brabender) has been conventionally used. 4-7
The weight / starch suspension is usually heated at a constant rate of 1.5 ° C./min, held at 95 ° C. for 10 to 30 minutes, and then cooled to 50 ° C., a viscosity / temperature curve, amylogram (FIG. 1)
Is a device for obtaining The horizontal axis indicates temperature, and the vertical axis indicates viscosity.

(Gelatinization Start Temperature) The gelatinization start temperature will be described with reference to FIG. FIG. 2 is a schematic diagram showing a viscosity-temperature curve and an amyogram for explaining the maximum viscosity and the gelatinization start temperature in the present invention. In the amyogram, the starch particles suspended in water begin to swell with heating, but while the starch particles are small, the viscosity curve runs above the baseline and shows no viscosity. As the degree of swelling increases, the viscosity starts increasing, and the viscosity curve rises from the baseline and rises rapidly. As shown in FIG. 2, the contact temperature at which the tangent of the curve at the rising point indicates an angle of 45 ° with the base line is called the gelatinization start temperature.

(Maximum viscosity) As heating is continued, the viscosity increases with swelling of the starch particles, but decreases rapidly when the starch swelling particles begin to disintegrate and gelatinize. In the amylogram curve, the viscosity at the maximum point where the viscosity changes from increasing to decreasing is referred to as the maximum viscosity.

(Water magnification)
The value divided by the weight of starch used is called the water magnification.

(Initial Adhesive Strength) Adhesive is applied to the flute, press-bonded to the liner, and heated immediately after heating, with sufficient adhesion that the liner and the flute do not peel off during the process from bonding to drying. Strength is required. The initial adhesive strength is the adhesive strength when the adhesive is not sufficiently dried, and it is known that the initial adhesive strength mainly depends on the viscosity of the applied starch paste. Therefore, a starch having a low gelatinization starting temperature, easily becoming a paste upon heating, and having a high maximum viscosity, that is, a starch having a large swollen particle size, such as potato starch, and a modified starch having similar properties are suitable.

(Measurement of Initial Adhesive Strength) The adhesive for cardboard was applied to a single-sided cardboard (RKA-280 × SCP125) using a double facer for testing, and a liner was applied.
Immediately after bonding with (RKA-280) at 170 ± 5 ° C. for 3, 5, or 7 seconds, measurement is performed using a pin tester. As is known to those skilled in the art, the adhesive strength is indicated as the adhesive strength of the cardboard adhesive per 42.5 cm ² (5 cm × 8.5 cm) of the test piece area of the cardboard sheet.

(Normal Adhesive Strength) This is the adhesive strength required when a cardboard product is used as a packaging / packaging material. Starch having a high gelatinization onset temperature of the amylograph, that is, corn starch, wheat starch, etc., exhibits excellent adhesive strength. The reason is that the starch having a high gelatinization start temperature does not completely gelatinize even after the lamination is completed, and has a high proportion of starch in the state of swollen particles.
In addition, starch having a low maximum viscosity has a strong cohesive force of starch particles,
This is because aging (recrystallization) is easy.

(Measurement of Normal Adhesive Strength) After bonding in the same manner as described above, after standing at a temperature of 23 ° C. and a relative humidity of 50% for 24 hours,
It measures using a pin tester like the initial adhesive strength.

(Relationship between Amylogram and Initial Adhesive Strength) The development of initial adhesive strength on a corrugator takes advantage of the rapid starch swelling from the gelatinization start temperature to the maximum viscosity of the amyogram, that is, the area of viscosity increase. ing. That is, the starch adhesive applied to the paperboard on the corrugator,
In the heating step, swelling (ie, thickening) is started, and the highest initial adhesive strength is exhibited at the maximum swelling (ie, highest viscosity).

(Relationship between Amylogram and Normal Adhesive Strength) After the pasting of the cardboard is completed, the starch at the low-temperature gelatinization start temperature exceeds the maximum viscosity, and forms a starch liquid in which the starch particles are disintegrated. Therefore, when the gelatinization start temperature is high and the high-temperature gelatinization start starch that leaves the starch swelling particles is present even after the lamination is completed, good normal adhesive strength is exhibited. It is well known that the adhesive strength of starch paste obtained by completely disintegrating and gelatinizing starch particles is weak.

The Y starch used in the adhesive for high-temperature and high-speed corrugated cardboard according to the present invention is required to have a maximum amyogram viscosity of 400 BU or more at a starch concentration of 4%, but is preferably in the range of 500 to 1500 BU. It is required that the gelatinization start temperature be 85 ° C or lower, but it is preferably in the range of 60 to 80 ° C. When the maximum amylogram viscosity of the Y starch is lower than 400 BU, the viscosity is low and the improvement of the initial adhesive strength required for the intended high-speed lamination is insufficient. If the gelatinization start temperature of the Y starch is higher than 85 ° C., even if it has a high viscosity, it cannot reach a high viscosity when achieving the initial adhesive strength.

The Z starch used in the adhesive for high-temperature, high-speed corrugated cardboard of the present invention is required to have a maximum amyogram viscosity of 120 to 20 BU at a starch concentration of 4%, and preferably in the range of 100 to 30 BU. It is required to have a gelatinization start temperature of 90 ° C. or more,
It is in the range of 2 to 100 ° C. If the maximum amylogram viscosity of the Z starch is lower than 20 BU, the molecular weight is too low to obtain a high adhesive strength, and if it is higher than 120 BU, the viscosity is greatly increased at the time of gluing or preserving the glue, resulting in poor stability. If the gelatinization start temperature of the Z starch is lower than 90 ° C., the viscosity is too high at the time of paste making and paste preservation, so that the stability is deteriorated.

The above-mentioned Y starch is not particularly limited as long as the above-mentioned maximum amylogram viscosity and gelatinization start temperature are within the above-mentioned ranges, but potato starch, sweet potato starch; their etherified starch, esterified starch, cross-linked starch and grafted starch starch;
And a mixture of two or more thereof.

The above-mentioned Z starch is not particularly limited as long as the above-mentioned maximum amylogram viscosity and gelatinization start temperature are within the above-mentioned ranges, but corn starch, wheat starch; their etherified starch, esterified starch, cross-linked starch and grafted starch And a mixture of two or more thereof.

Among the starches used in the present invention, the modified starches include esterified starches such as acetic acid, propionic acid, maleic acid and phosphoric acid, etherified starches such as carboxymethyl, hydroxyethyl and hydroxypropyl, and epichlorohydride. Examples thereof include crosslinked starches such as phosphorus, formalin, maleic acid, and phosphoric acid, and grafted starches such as acrylonitrile and acrylamide.

The weight ratio of Y starch: Z starch is 3:97 to 2
5:75, but preferably 5: 9
The range is 5 to 20:80. If the amount of the Y starch is less than 3% by weight and the amount of the Z starch is more than 97% by weight, the amount of the Y starch is small and the effect cannot be sufficiently obtained. If the amount of the Y starch is more than 25% by weight and the amount of the Z starch is less than 75% by weight, the viscosity is increased at the time of gluing or preserving the glue, resulting in poor stability. Insufficient adhesive strength.

The water magnification is 2 to 5 times, preferably 2.5 to 4 times.
Twice, Ford cup viscosity is 20-50 seconds (38 ° C)
, Preferably in the range of 25 to 50 seconds (38 ° C.).

The adhesive for corrugated cardboard used in the present invention can be used in the case of a water-resistant paste in which a water-resistant agent is used in combination, and the same effect is exerted.

[0040]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

A potato starch: corn starch ratio of 1
500 kg of the starch mixed at 0:90 was suspended in 900 liters of water heated to 43 ° C. and 462.5 kg of 2.64
% Caustic soda and gradually add boric acid 5.85k
g was added to complete the preparation of the cardboard adhesive. The prepared size liquid has a water magnification of 2.7 times and a Ford cup viscosity of 38.
Seconds (38 ° C.). Using the above adhesive, lamination was performed at a bonding temperature of 170 ± 5 ° C. with a double facer for testing to obtain a cardboard. The initial and normal adhesive strength of the obtained cardboard was measured with a pin tester, and the results are shown in Table 1. From the above results, it was found that the resin had good adhesive strength.

Example 2 Table 2 shows the results obtained by treating starches mixed with a potato starch: corn starch ratio of 15:85 in the same manner as in Example 1 as Example 2. From the above results, it was found that the resin had good adhesive strength.

Example 3 The results obtained by treating each of the starches obtained by mixing acetic acid potato starch (DS = 0.05): corn starch at a ratio of 10:90 in the same manner as in Example 1 are shown in Example 3. 1 is shown. From the above results, it was found that the resin had good adhesive strength.

Example 4 The results obtained by treating each of starches mixed with a sweet potato starch: corn starch ratio of 10:90 in the same manner as in Example 1 are shown in Table 1 as Example 4. From the above results, it was found that the resin had good adhesive strength.

[0045]

[Table 1]

Comparative Examples 1 and 2 Corn starch and potato starch were each used alone in Example 1.
Table 2 shows the results obtained by performing the same treatment as in Comparative Examples 1 and 2. Neither shows sufficient performance as a cardboard adhesive for high-speed lamination, and in the case of cornstarch alone, the initial adhesive strength is low, and potato starch is strongly thickened at the time of gluing, making lake making difficult. There was no practical use.

Comparative Examples 3 and 4 The results obtained by treating starches mixed with potato starch and corn starch in the ratios of 30:70 and 50:50 in the same manner as in Example 1 are shown in Comparative Examples 3 and 4. Table 2
It was shown to. As a result, the initial adhesive strength was good, but the normal adhesive strength was low. In addition, when the paste was made, the viscosity increase during storage was very unstable, and practical use was difficult.

Comparative Example 5 A starch obtained by mixing waxy corn starch and corn starch at a gelatinization temperature and a maximum viscosity of 10:90, which is a starch contained in Y starch but containing almost no amylose, was the same as in Example 1. Are shown in Table 2 as Comparative Example 5. As a result, the initial adhesive strength was good, but the normal adhesive strength was low.

Comparative Examples 6 and 7 The ratio of potato starch to corn starch was 10:90, 5
Table 2 shows the results obtained by treating in the same manner as in Example 1 except that the starch mixed at 0:50 was subjected to the bonding conditions at 130 ° C. for 3, 5, 7 seconds, respectively, as Comparative Examples 6 to 7. Indicated. In the case of the bonding conditions of 130 ° C., the initial and normal adhesive strengths were inferior to those of the corn starch alone of Comparative Example 1 and the potato starch alone of Comparative Example 2 bonded at 170 ° C. In the mixing, the same performance as Comparative Example 1 is obtained, but from the viewpoint of the initial adhesive strength and the normal adhesive strength,
Lamination is possible, but no speed increase is expected.

[0050]

[Table 2]

Examples 5 to 7 and Comparative Examples 8 to 11 Corrugated cardboard adhesive prepared in the same manner as in Example 1 using starch mixed with a potato starch: corn starch ratio of 10:90 and 50:50. (NC glue) at Rengo Co., Ltd. Wakayama Plant, machine width 2200 mm, nominal laminating speed 250 m / min, hot plate temperature; Paste to
The bonding state was examined. The maximum speed at which the bonding state is good is described in Table 3, but the mixture at 10:90 in Examples 5 to 7 was compared with the corn starch alone in Comparative Examples 9 to 11 in terms of the bonding speed. Increased by 30 to 51 m / min.
On the other hand, about 50:50 mixed in Comparative Example 8, the rise was only 10 m / min, which was not sufficient, and the normal adhesive strength was slightly lowered.

[0052]

[Table 3]

Examples 8 to 10 and Comparative Examples 12 to 15 Potato starch: corn starch ratios of 8:92 and 5
The starch mixed at 0:50 was used for corrugated cardboard glue produced in a one-tank system, and was used at the Eniwa Plant of Rengo Co., Ltd. (machine width 2200 mm, nominal laminating speed 300 m /
Min., Hot plate temperature; 190 ° C.) under a condition such as a base paper configuration shown in Table 4 and the state of bonding was examined. Table 4 shows the results. 8: 9 of Examples 8 to 10
In the case of the mixture obtained in No. 2, the laminating speed was 34 to 45 m / min, which was close to the nominal capacity, as compared with the corn starch alone of Comparative Examples 13 to 15. In contrast, 50: 5
In Comparative Example 12 mixed with 0, the increase was only 10 m / min, which was not sufficient, and the normal adhesive strength was slightly reduced.

[0054]

[Table 4]

[0055]

According to the present invention, Y starch having a high viscosity / low gelatinization start temperature and Z starch having a low viscosity / high gelatinization start temperature are 3:97.
By mixing at about 25:75, the initial adhesive strength was dramatically improved while maintaining good normal adhesive strength. This effect was also proved in the corrugator, which manufactures corrugated cardboard, and the bonding speed was dramatically increased. This rise is unique.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an amyogram measured at a concentration of 4% by weight of one embodiment of the adhesive for high-temperature and high-speed corrugated cardboard of the present invention, and also schematically shows a state where starch particles are swollen and gelatinized. ing.

FIG. 2 is a schematic diagram showing a viscosity-temperature curve for explaining the maximum viscosity and the gelatinization start temperature in the present invention.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Akitomo Terada 594 Undai-cho, Kashihara-shi, Nara Prefecture Sanwa Starch Industry Co., Ltd. (72) Inventor Toshihiro Miki 2-5-2-5 Umeda, Kita-ku, Osaka-shi, Osaka Prefecture Rengo Co., Ltd. (72) Inventor Masaru Yamada Nakahara-cho, Toyohashi-shi, Aichi 1 Oike 1 Rengo Co., Ltd. Toyohashi Plant F-term (reference) 3E078 AA20 CC23X 4J040 BA111 BA121 BA132 MA09 MB03 NA07

Claims (4)

[Claims] (1) A starch having a maximum amylogram viscosity of 400 BU or more at a starch concentration of 4% and a gelatinization starting temperature of 85 ° C.
A high viscosity / low gelatinization start temperature starch (Y starch) having:
And (b) the highest viscosity of the amylogram at a starch concentration of 4% 1
It contains at least two kinds of low-viscosity / high-gelatinization start temperature starch (Z starch) having 20 to 20 BU and having a gelatinization start temperature of 90 ° C. or more, and both Y starch and Z starch contain amylose. An adhesive for high-temperature and high-speed corrugated cardboard, wherein the weight ratio of Y starch: Z starch is in the range of 3:97 to 25:75. 2. The Z starch wherein said Y starch is selected from the group consisting of potato starch, sweet potato starch; their etherified starch, esterified starch, crosslinked starch and grafted starch; and a mixture of two or more thereof. Is corn starch,
Wheat starch; their etherified starch, esterified starch,
The adhesive of claim 1 selected from the group consisting of cross-linked starch and grafted starch; and mixtures of two or more thereof. 3. The weight ratio of Y starch: Z starch is 5: 9.
The adhesive for cardboard according to claim 1, wherein the adhesive ratio is in the range of 5 to 20:80. 4. The adhesive for cardboard according to claim 1, wherein the amylose content of the Y starch and the Z starch is in the range of 20 to 30% by weight.