JPH02281090A - Adhesive for corrugated boards - Google Patents

Abstract

PURPOSE:To obtain an adhesive which improves the operability in adhesive preparation, speed increase in corrugator, warpage of boards and adhesion of the corrugated part by mixing high-viscosity starch and low-viscosity starch at a specific ratio so that the volume of water added and the viscosity are adjusted in specific ranges. CONSTITUTION:The subject adhesive is obtained by mixing (A) a starch of high amylogram maximum viscosity (preferably potato starch of more than about 700 BU in 4% starch concentration) and (B) another starch of low amylogram maximum viscosity (preferably corn starch or wheat starch of less than about 300 BU) at a ratio of 3/7 to 9/1, preferably 4/6 to 8/2 so that the water content becomes 2 to 5 times the solid component and the Ford cup viscosity ranges from 20 to 50 seconds at 30 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an improved carrierless corrugated adhesive for use in high-speed corrugators, which has become rapidly popular in recent years.

[In order of pI to be solved by conventional techniques and inventions] In recent years, corrugators, which are cardboard manufacturing machines, have tended to become larger and faster, and the demand for lower temperatures in the heating and drying process has also increased. are doing. Therefore, high speed,
The development of low-temperature cardboard adhesives is an important issue.

Various methods have been used to prepare corrugated board adhesives. Representative examples include the Stein-Hall method (hereinafter abbreviated as the 814 method) and the no-carrier method (hereinafter abbreviated as the 814 method).
(hereinafter abbreviated as No method).

The EIH method uses a mixture of starch (carrier part) that has been completely gelatinized by alkali and heat and ungelatinized starch (main part), while the No method uses an alkali solution after suspending starch in water. The suspension is made by partially swelling the starch until it reaches a predetermined viscosity so as not to gelatinize when added. Both are applied to paperboard using a fulgator and dried by heating to attach the cardboard. be exposed.

Examples of such conventional methods include those described in Japanese Patent Publications No. 59-28594, No. 59-28595, and No. 59-28596, in which four characteristics required of starch as a corrugated board adhesive are (1) Considering the time required for gelatinization, (2) gelatinization start temperature, (3) viscosity after gelatinization, and (4) adhesive strength after gelatinization, saponified vine starch ester is a corrugated board adhesive that satisfies the above conditions. In other words, by esterifying starch, the gelatinization temperature is lowered and the viscosity is increased, thereby attempting to satisfy the above conditions. However, as will be explained later in the comparative example, it is difficult to say that it is industrially sufficient for use in high-speed corrugators.

JP-A-58-173172 has the same concept as above,
Esterified tapioca starch, especially one having 0.01 to 010 ester groups per glucose unit, is used, but as mentioned above, this is also not considered to be industrially sufficient.

Japanese Patent Publication No. 59-23774 is based on the SH method, in which at least two types of starches with different gelatinization temperatures are mixed with water, then the starch with a lower gelatinization temperature is gelatinized, used as a part of the carrier, and the starch with a higher gelatinization temperature is mixed with water. This is a cardboard adhesive whose main component is starch at gelatinization temperature. This is intended to improve workability in preparing part of the carrier, and during application with a corrugator, the main part is composed solely of starch having a high gelatinization temperature. Therefore, the adhesive force is equivalent to that of corn starch alone, and no industrial advantage is recognized.

As mentioned above, conventional corrugated cardboard adhesives are all used in recent years,
Attempts were made to improve corrugated cardboard adhesives for high-speed corrugators, but none of them were satisfactory in terms of performance.

The present invention provides an adhesive for corrugated board produced by a no-carrier method, in which starch, its main component, swells and gelatinizes uniformly and rapidly, and in addition, exhibits strong adhesive strength even when heated at low temperatures. The viscosity of the paper is designed to be within a controllable range, and this improves workability during glue making, increases the speed of corrugators, saves energy, prevents warping of corrugated sheets, and the adhesive strength of the so-called "anko" part of double-walled corrugated cardboard. The purpose of this invention is to provide an adhesive that can greatly contribute to the improvement of.

[Means to solve the problem]

Although various discussions have been made regarding the mechanism by which corrugated board adhesive functions, it remains within the scope of experience and cannot be clearly explained.

However, for the main starch of the gH method and the partially swollen starch of the No method, adhesive is applied to the top of corrugated corrugated paperboard, a liner is pressed to the top of the corrugation coated with the adhesive, and It is generally accepted that latent adhesives are fully functional only after the application of heat and pressure to gelatinize and develop adhesive strength. Therefore, the inventors of the present invention have developed the necessary materials to design a high-speed, low-temperature Fulgator adhesive while maintaining ideal workability, adhesive viscosity, and storage stability during adhesive manufacturing. As a result of extensive research into the properties of starch, the present invention was achieved.

That is, the present invention uses at least two types of starches having different maximum viscosities in the amylogram (high viscosity starch is A starch, starch A is a high viscosity starch,
Low viscosity starch (abbreviated as B starch) is mixed at a ratio of A11l powder/B starch: 3/7 to 9/1, and the water ratio is 2 to 9.
This is a high-speed, low-temperature heating adhesive for corrugated board, which is characterized by being prepared to have a viscosity in the range of 20 to 50 seconds (30°C). Preferably, the A starch is potato starch and/or a modified starch that has been modified, chilled, esterified, crosslinked, and/or grafted and has a maximum amylogram viscosity equal to or higher than 700 BU at a 4% starch concentration; The starch may be corn starch, waxy corn starch, wheat starch, and/or tapioca starch and/or etherified, esterified, crosslinked,
and/or grafted starches, further preferably modified starches with a maximum amylogram viscosity equal to or lower than 300 BU at 4% starch concentration.
The mixing ratio of H powder ranges from 4/6 to 872.

In such a corrugated board adhesive of the present invention, when it is applied with a corrugator, the starch is partially swollen but exists as ungelatinized particles, and it is not until it is heated that the starch further swells and gelatinizes. . Note that the starch is composed of an appropriate mixing ratio of two or more types of starch having greatly different maximum viscosities in the amylogram, and is within an appropriate water ratio and viscosity range at the time of starch making.

The corrugated board adhesive of the present invention is characterized by the combined use of different kinds of starches, one of which is potato starch and/or various modified starches, and the maximum viscosity in the amylogram is 4% of starch.
The other is tapioca starch and/or various modified starches, which have a large viscosity such that the highest amylogram viscosity is equal to or lower than 300 BU at a starch concentration of 4%. Being different is important.

What is particularly important is that even if a corrugated board adhesive uses a mixture of two or more types of starch with different gelatinization start temperatures, the purpose of the present invention cannot be achieved unless the two types have significantly different maximum viscosities in the amylogram. For example, the gelatinization start temperature of tapioca starch and waxy corn starch is lower than that of potato starch (64-68°C), but since the maximum viscosity is lower than that of potato starch, it is different from cornstarch at a high temperature (91°C). Even in combination, sufficient adhesive strength cannot be obtained.

In addition, when using potato starch alone, good adhesive strength can be obtained in the SR method, but on the other hand, in the No method, the viscosity increases rapidly when preparing the paste solution for corrugated board adhesive.
Moreover, since it has a high viscosity, it is difficult to control the viscosity, which hinders work.

Therefore, in order to be able to make glue under normal conditions in the No method and to exhibit satisfactory adhesion, AiI! 2 powder/
The ratio of B starch is from 3/7 to 971, preferably 4/6
should be in the range from 872 to 872.

Among the starches used in the present invention, A starch includes potato starch and/or esterified, etherified, crosslinked, and/or
Or grafted starch with maximum amylogram viscosity of 4% starch
Any modified starch with a concentration equal to or higher than 700 BU may be used; on the other hand, B1! The flour is corn starch, waxy corn starch, wheat starch, and/or tapioca starch, and/or etherified, esterified, crosslinked, and/or grafted starch, and the maximum amylogram viscosity is equivalent to or equal to 300 Bυ at 4% starch concentration. Any modified starch with a lower concentration may be used, but examples of modified starches include esterified starches such as acetic acid, succinic acid, maleic acid, and phosphoric acid, etherified starches such as carboxymethyl, hydroxyethyl, and hydroxypropyl, and shrimp chlorohydride. Rin,
Examples include crosslinked starches such as formalin and maleic acid, and grafted starches such as acrylonitrile and acrylamide.

In the case of esterification, etherification and grafting reactions, the maximum amylogram viscosity increases with increasing degree of substitution (D, S, number of substituents per Nigelcose unit). In the case of a crosslinking reaction, as the degree of crosslinking increases, the gelatinization initiation temperature tends to increase, and the maximum viscosity tends to increase slightly and then significantly decrease. Therefore, both A and 1 processed starch can be produced by selecting the degree of substitution, but normally, A and S are 0.0.
It is selected from a range of 1 to 0.10.

The mixing ratio of both A and 'B starches is determined by considering workability and adhesive strength during glue making, but normally the ratio of A starch/B starch is 3/7 to 9/1. , preferably 4
The range is from /6 to 872.

〔Example〕

The present invention will be explained below with reference to examples, and the technical terms used in the above description and the following examples will be explained.

Water magnification: Value obtained by dividing the total weight of water used during glue making by the weight of starch used. Initial adhesive strength: Corrugated cardboard adhesive was applied to single-sided cardboard (BX300XSOP 125) using a double facer for testing. , liner CB-300) for 3 seconds at 120 to 130°C, and then immediately measured using a pin tester Normal adhesive strength: After laminating in the same manner as above, temperature = 20°C
1 After being left at relative humidity: 65% for 24 hours, the aqueous suspension of starch was subjected to an amylograph (two-blade paddle type manufactured by Plapendar, heating rate: 1.5°C/min). In the temperature-maximum viscosity near-amylogram curve at a point where the tangent of the rising curve of the amylogram curve forms an angle of 45 degrees with the base line, the viscosity at the maximum point increases after gelatinization starts and then begins to decrease. 1. 5001 cf of starch mixed at a potato starch/hoon starch ratio of 7/3 was suspended in 9001 water heated to 43°C, 462.5 Kt of 2.64% caustic soda was gradually added, and II! ! Afterwards, 5.85 Ky of boric acid was added to complete the preparation of the adhesive for corrugated board. The prepared paste had a water magnification of 2.7 times and a 7-odd cup viscosity of 38 seconds (30° C.). The adhesive was used to bond the cardboard using a double 7 Acer for testing, and the initial and normal adhesive strength of the cardboard was measured using a bin tester, as shown in Table 1. The table also shows the maximum viscosity of the amylogram at 4% concentration of the starch used.

Examples 2 to 5 Potato starch/corn starch ratio; 515, phosphorylated corn starch/corn starch; 7/3, acetated potato starch/corn starch; 7°/3, and potato starch/acetate tapioca; 7/3 starch, respectively. The same treatment as in Example 1 was carried out, and the obtained results are shown in Table 1 as Examples 2 to 5.
0 Example 6 The potato starch/cornstarch ratio was 7/3, and the results obtained by processing in the same manner as Example 1, except that the water content was 3.5 times, are shown in Figure 1. Ta.

All of the above examples exhibited satisfactory initial and normal adhesive strengths.

Comparative Examples 1 to 5 Corn starch, tapioca starch, tapioca acetate starch, potato starch, and tapioca starch/corn starch ratio;
7/3 starch was treated in the same manner as in Example 1, and the obtained results are shown in Table 1 as Comparative Examples 1 to 5. None of them exhibited sufficient performance as adhesives for corrugated board, and in particular, in Comparative Example 4 using potato starch alone, the viscosity thickened during glue making was so severe that it was impossible to use it practically.

Comparative Example 6 The adhesive strength using a glue obtained by processing in the same manner as in Example 1 except that the mixture ratio of potato starch/Hoon starch was 7/3 and the water content was diluted 6 times was as follows. As shown in -1, it was not practically sufficient.

Comparative Example 7 For a potato starch/corn starch mixing ratio of 7/3, 4
Example 6 except that 05 Kf of 2.64% caustic soda was used.
The results obtained are shown in Table 1.
The glue viscosity was low and the adhesive strength was insufficient.

Example 7 Using a cardboard adhesive made in the same manner as in Example 1 with a potato starch/corn starch mixing ratio of 7/3, a paste was prepared using a cardboard adhesive manufactured by Mitsubishi Heavy Industries ■ (machine #il: 2000 cm, Nokani 2).
Double-sided corrugated cardboard was laminated using a corrugator of 00 yIL/min under the conditions listed in Table 2, and the adhesive strength of the so-called "red bean paste part" was measured and shown in Table 2. The temperature reached at the adhesive portion at the top of the step was measured using thermo tape.

Adhesive part humidity is low at 75°C and 18 n rn /mi
Good adhesion was exhibited despite the high speed of n.

Comparative Example 8 Using a cardboard adhesive made from cornstarch in the same manner as in Example 1, lamination was carried out under the conditions listed in Table 2 using the same Fulgator as in Example 7, and the adhesive performance was evaluated. It is shown in Table-2.

The adhesive of the present invention exhibited superior adhesive strength even at low heating temperatures and high speeds, compared to corn starch alone. This result shows that the method of the present invention can be applied at higher speeds if laminating at the same temperature, and at lower temperatures if laminating at the same speed. .

6. Contents of amendment (1) Page 8, line 16 of the specification, “High temperature (91°C)” was changed to [
Corrected to high temperature (91'C) J.

(2) Page 11, line 9 [(Bx300xSCP 1
25) Correct J to r (B-300XSCP-125)J.

that's all

Claims (1)

[Scope of Claims] 1. At least two types of starch having different maximum amylogram viscosities (high viscosity starch is abbreviated as A starch, and low viscosity starch is abbreviated as B starch), with an A starch/B starch ratio of 3/7 to Mix in the range of 9/1, water magnification 2 to 5 times, food cup viscosity 2
A high-speed, low-temperature heating adhesive for corrugated board, characterized in that it is prepared to have a heating time in the range of 0 to 50 seconds (30°C). 2. A starch is potato starch and/or etherified, esterified, crosslinked, and/or grafted starch, and the maximum amylogram viscosity is 700 BU at 4% starch concentration.
an equivalent or higher modified starch, and the B starch is corn starch, waxy corn starch, wheat starch, and/or tapioca starch and/or etherified, esterified, crosslinked, and/or grafted starch, and the amylogram peak viscosity is The adhesive for corrugated board according to claim 1, which is a modified starch equivalent to or lower than 300 BU at a starch concentration of 4%. 3. The adhesive for corrugated board according to claim 1, wherein the mixing ratio of starch A/starch B is in the range of 4/6 to 8/2.