JPS5823424B2 - How to bond cardboard using quick-curing adhesive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for adhering corrugated boards, which uses a rapid curing adhesive and does not require a heating operation during lamination of the corrugated boards.

Conventionally, starch-based adhesives have generally been used to manufacture corrugated cardboard.

This starch-based adhesive is made by gelatinizing the starch using a combination of steam heating and caustic soda and applying it as a sticky adhesive to the surface of the cardboard to be bonded.
A method is used in which the water content of this glue solution is evaporated by heating, and the bonding operation is completed by drying and curing.

However, the thermal energy consumption in this lamination process accounts for a very large proportion of the total energy consumption of a corrugated board factory, so if this heating operation during lamination was omitted, the energy saving effect would be significantly large. becomes.

In view of this situation, the present inventors conducted intensive research to develop a method for adhering corrugated boards that does not require heating operations during corrugated board lamination. The present invention was completed based on the discovery that the present invention has excellent performance in achieving the objective.

That is, the present invention applies a high-temperature, high-concentration paste solution of high-amylose corn starch or its processed starch having an amylose content of 50% or more to the laminating surface of corrugated cardboard, and immediately after laminating, it is left to cool or forcedly cooled. This is a corrugated board bonding method using a rapid curing adhesive, which is characterized in that the bonding is completed in several steps.

The high amylose corn starch used in the present invention is a starch produced from special corn created through breeding, and has a higher amylose content (about 50%) than normal corn starch (about 25%).
% or more).

High amylose corn starch has a high amylose content, so (a) it is difficult to gelatinize under normal conditions;
B) Highly concentrated paste liquid can be prepared, C → extremely easy to age,
It has characteristics such as (b) strong film strength and (e) high adhesive strength.

High amylose corn starch having such characteristics is extremely suitable as an adhesive material for achieving the object of the present invention.

That is, since the present invention aims to provide a method for adhering cardboard at °C which does not require heating operation when pasting the cardboard, (a) the size liquid is used to reduce the amount of water evaporation. (b) The adhesive must have the ability to rapidly gel, as it is required to cause a setting phenomenon immediately after being applied to the bonding surface of the cardboard. Although these are necessary conditions, high amylose corn starch can fully satisfy these conditions.

It goes without saying that the use of a hot melt adhesive is an effective means for such a so-called cold-set laminating method that does not require heating operations when laminating corrugated boards.

However, the use of hot-melt adhesives is not desirable in countries like Japan, where the rate of recovery and reuse of waste cardboard is extremely high, as it poses a major hindrance to the recovery and reuse of waste cardboard.

Also, since hot melt adhesives are petrochemical products,
The fact that it will become increasingly difficult to obtain resources will also become a major problem in the future.

In this regard, corn and corn starch produced from it are a resource that is attracting attention as an energy source to replace oil in the future era of oil shortages, as seen in "Ga5ohol", and it can be used as an adhesive with less trouble when collecting waste paper. In addition to being an adhesive material, it can be said to be an excellent resource as a corrugated board adhesive material.

In the method of the present invention, water is added to high amylose corn starch, and the temperature is about 80 to 100°C, and the concentration is 20 to 20.
A high-temperature, high-concentration paste solution of about 50% by weight is prepared, and this high-temperature, high-concentration paste solution is applied to the lamination surface of the hot corrugated board, and after lamination, the lamination is immediately left to cool or forced to cool. This cooling causes the starch paste to rapidly harden, creating a strong bond.

The fast-curing adhesive material used in the method of the present invention includes not only high-amylose corn starch having an amylose content of 50% or more, but also high-amylose corn starch that is decomposed into starch using α-amylase according to a known method. Amylase-treated high-amylose corn starch obtained by processing with enzymes, acid-treated high-amylose corn starch obtained by processing with inorganic or organic acids such as hydrochloric acid, sulfuric acid, acetic acid, etc., and throat-processed high-amylose corn starch are also effective. be.

If high amylose corn starch is treated with amylase or acid, it is possible to further reduce the viscosity of the starch paste, which not only increases the paste concentration, but also speeds up the aging process. Rapid curing of the liquid can be further promoted.

According to the method of the present invention, strong adhesive strength can be obtained without the need for heating operations when bonding corrugated boards, so not only can thermal energy consumption in a corrugated board factory be significantly reduced, but also true melt adhesives can be used. There is no major hindrance to the collection and reuse of waste paper, unlike when paper is used.

Next, examples of the present invention will be shown.

Example l Amylose content produced by wet milling 51
10% high amylose corn starch to 9 parts water
01 was added to form a starch suspension, which was then treated with an onrator using indirect heating using steam to heat and gelatinize the high amylose corn starch.

A high-temperature, high-concentration glue solution with a temperature of about 90°C and a concentration of about 33% by weight is discharged from the outlet of the onlator onto the top of a single-corrugated cardboard. /m (as a dry substance), and after overlaying a kraft liner for corrugated board on this, cold air was blown to cool and harden the paste liquid, thereby completing the lamination of the corrugated board.

Example 2 100 kg of corn starch with an amylose content of 51% was suspended in 1501 water, and 5 (l) of an α-amylase preparation (manufactured by Daiwa Kasei KK, T-5) was added to give a concentration of 0.1%. Adjust the pH to 6 with an aqueous solution of calcium hydroxide.
．． Adjusted to 5.

Next, this suspension was treated with an onlator that uses indirect heating using steam to heat and gelatinize the amylose corn starch (amylase treatment).

The lamination of the cardboard was completed in the same manner as in Example 1 using a high-temperature, high-concentration glue solution discharged from the outlet of the onlator at a temperature of about 95 DEG C. and a concentration of about 40% by weight.

Example 3 High amylose with an amylose content of 70% and 100 kg of 5-sorghum starch were suspended in 2,001 liters of water, and concentrated hydrochloric acid 2-2
Add 9 to about 0. A solution of IN in hydrochloric acid was used and the mixture was reacted for 20 hours at a temperature of 50° C. with gentle stirring.

Next, the pH was adjusted to 6 with a 5% aqueous sodium hydroxide solution.
5, dehydrated, dried in a hot air dryer at a temperature of 50°C, and pulverized to obtain acid-treated iamylose corn starch.

Add 201 kg of water to 10 kg of this starch to make a starch suspension, which was stirred in a high-pressure cooker and then heat-treated at 110°G for 30 minutes at a temperature of about 90°C and a concentration of about 33% by weight.
Acid treatment...Iamylose corn starch paste liquid was obtained.

This high-temperature, high-concentration size liquid was kept at a temperature of about 90°C, and using this size liquid, the lamination of cardboard was completed in the same manner as in Example 1.

Comparative Example 1 The lamination of cardboard was completed in the same manner as in Example 1, except that common corn starch with an amylose content of 24% was used.

In order to clarify the characteristics of the corrugated board bonding method using the rapid curing adhesive of the present invention, after laminating the corrugated cardboards laminated according to the above examples and comparative examples (after stacking the single corrugated corrugated cardboard and the liner) Changes in adhesive strength over time were measured.

The results are shown in the table below.

The adhesive strength (kg) of the cardboard was measured using a pin tester according to the cardboard adhesive strength testing method (JIS-Z-0402).

Claims (1)

[Scope of Claims] 1. A high-temperature, high-concentration paste solution of high-amylose corn starch or its processed starch having an amylose content of 50% or more is applied to the bonding surface of the cardboard, and immediately after the bonding is left to cool or forced to cool. A method for bonding cardboard using a rapid-curing adhesive, which is characterized in that the bonding process is completed using a rapid curing adhesive. 2. A method for bonding cardboard using the rapid curing adhesive according to claim 1, wherein the processed high amylose corn starch is amylase-treated high amylose corn starch. 3. A method for bonding cardboard using the rapid curing adhesive according to claim 1, wherein the processed high amylose corn starch is acid-treated high amylose corn starch. 4. A corrugated board bonding method using the rapid curing adhesive according to claim 1, wherein the size liquid temperature is 80 to 100°C. 5. A method for bonding cardboard using the rapid curing adhesive according to claim 1, wherein the glue concentration is 20 to 50% by weight.