JPH11323282A - Adhesive for cardboard box - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a starch-based adhesive for cardboard box of Stein Hall process capable of improving high-speed lamination suitability while maintaining viscosity stability. SOLUTION: In this adhesive for cardboard box made by Stein Hall process, a starch having 2.3-2.6 water/starch ratio, 7-9 main starch/carrier starch ratio, <=400 g/m2 water retention and 15-25 cps Hercules viscosity, using an acid treated maize starch as the carrier starch and having 300-1,000 cps Brookfield viscosity at 50 deg.C in 11.5 wt.% of a carrier starch completely gelatinized solution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a starch-based adhesive used for producing a corrugated cardboard sheet. More specifically, the so-called Steinhole method invented in the United States in 1934 (US Pat.
102937, 221257, and 130266)
The present invention relates to a starch adhesive for corrugated cardboard manufactured in the above, while maintaining viscosity stability in the production of corrugated cardboard sheets, reducing the water content contained in the adhesive, and increasing the main starch ratio to improve high-speed bonding suitability. The present invention relates to an improved cardboard adhesive.

[0002]

2. Description of the Related Art Conventionally, the Steinhole method (hereinafter referred to as SH method) has been generally used as an adhesive for cardboard. This is prepared by mixing a carrier consisting of starch paste liquid completely gelatinized by alkali and heat and a main consisting of ungelatinized starch, and generally has a water / starch ratio (hereinafter referred to as double water ratio). And a main starch / carrier starch ratio (hereinafter referred to as M / C ratio) of 3 to 6 is used.

[0003] In this starch adhesive for corrugated cardboard by the SH method, the main starch is gelatinized by moisture, heat and alkali in the adhesive, and exhibits permanent adhesive strength. The role of the carrier starch is to uniformly disperse the main starch in the adhesive to prevent sedimentation, to apply the main starch uniformly to the top of the step in the adhesive application device on the corrugator, and to apply the applied adhesive It has been said that water is retained so that water is not excessively absorbed by the liner and the core from the liquid, and that initial adhesion strength is exhibited by evaporation and absorption of water.

[0004] In recent years, corrugated cardboard manufacturing equipment (hereinafter referred to as corrugator) has been increasing and speeding up.
The rate of adhesion is determined by the rate of adhesion. In order to improve the rate of adhesion between the core and the liner by the adhesive, a higher concentration is required.

[0005] Japanese Patent Publication No. 55-35076 discloses a method in which acid-treated starch, oxidized starch and dextrin are mixed with raw starch to obtain a carrier starch. This is to set the water doubling rate to 2.3 to 3.3 and the M / C ratio to 1.5 to 4. Japanese Patent Publication No. 58-13109 discloses an apparatus having a water recycle ratio of 1.86 to 9 and an M / C ratio of 2 to 8.

[0006] Usually, the viscosity used as a corrugated cardboard adhesive is 200 to 1000 cps in Brookfield viscosity.
Range. However, when 2.3 to 2.6 times water is prepared with a generally used formulation of M / C ratio = 3 to 6, the finished Brookfield viscosity becomes several thousands to several tens of thousands cps, and the It is too bad to use.

Japanese Patent Publication No. 55-35076 discloses M / C
When the ratio of water is adjusted to 2.3 to 3.3 at a ratio of 1.5 to 4, the fluidity and viscosity stability at 2.3 to 2.6 times water in this M / C ratio range. Since the viscosity becomes worse and the Hercules viscosity becomes too high, it becomes difficult to control the glue application amount in the corrugator. In addition, the initial adhesiveness derived from the main starch cannot be sufficiently obtained, and the use of a large amount of expensive carrier starch is disadvantageous economically.

Japanese Patent Publication No. 58-13109 discloses 2.3.
The preferred M / C ratio in water up to 3 times is 4 to 6,
In this range, it is difficult to control the finished viscosity, viscosity stability and Hercules viscosity especially in 2.3 to 2.6 times water, and it is difficult to obtain the initial adhesive strength derived from the main starch. The minimum water doubling rate in the example in Japanese Patent Publication No. 58-13109 is 2.92 times water, and is 2.3 to 2.
No problems or solutions when the water rate is reduced to 6 times water are disclosed.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a corrugated cardboard adhesive which exhibits excellent high-speed lamination suitability while maintaining the viscosity and stability of the adhesive. It is intended to provide.

[0010]

The present invention comprises the following constitution. That is, in the water-based corrugated cardboard adhesive produced by the SH method, the water doubling rate is 2.3 to 2.6 and the M / C ratio is 7
~ 9, and GRAVIMETRIC manufactured by KALTEC SCIENTIFIC, INC.
0.1MPa by WATER RETENTIONMETER AA-GWR,
The water retention at 100 seconds is 400 g / m ² or less, the viscosity at 30 ° C. by a Hercules viscometer, 4400 rpm, the range when using F Bob is in the range of 15 to 25 cps, and the concentration of the complete gelatinization solution as a carrier starch. 11.5% by weight of 5
Brookfield viscosity at 0 ° C of 300-100
It is characterized in that a material in the range of 0 cps is used.

The present inventors have intensively studied a starch-based adhesive produced by the Steinhole method as an adhesive for corrugated cardboard for improving the suitability for high-speed lamination. As a result, M
When the / C ratio is in the range of 7 to 9, the water doubling rate is 2.3 to 2.
By setting it to 6, good initial adhesive strength and permanent adhesive strength were obtained at the time of high-speed lamination, and it was found that it was important to control the water retention as a factor. Further, when the water ratio is in the range of 2.3 to 2.6, the Hercules viscosity is 15 to
It has been found that the control of the glue application amount in the corrugator can be easily performed by setting the rate to 25 cps. Further, as a carrier starch that satisfies the above conditions, the Brookfield viscosity at 50 ° C. of a complete gelatinized solution having a concentration of 11.5% is 300-1.
The present inventors have found that a carrier starch in the range of 000 cps exhibits excellent performance and completed the present invention.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. In the present invention, an adhesive composition mainly comprising a main starch and a carrier starch is employed. The main starch used in the present invention is not particularly limited. For example, ground starch such as corn starch, wheat starch, sago starch, rice starch,
Any of underground starches such as tapioca starch, sweet potato starch and potato starch may be used, but corn starch, wheat starch and tapioca starch are advantageous in terms of stable supply and economy.

It is desirable that the carrier starch used in the present invention is inexpensive, has low spinnability, and is appropriately modified to have a low viscosity. Suitable for this purpose are those having a concentration of 11.5% by weight of the complete gelatinization liquid and a Brookfield viscosity at 50 ° C. of 300 to 1000 cps,
Particularly, acid-treated corn starch is preferred. If the Brookfield viscosity exceeds 1000 cps under the above-mentioned conditions, the viscosity of the finished adhesive liquid becomes too high, and the fluidity required for the circulation system cannot be secured. When a material having a viscosity lower than 300 cps is used, the stability of the adhesive liquid is deteriorated, and a large amount of precipitate is generated during storage, resulting in uneven concentration.

In the present invention, the water doubling rate is 2.3 to 2.6.
It is necessary to be. In this water content range, the initial adhesive strength can be improved without deteriorating the permanent adhesive strength, adhesive viscosity and adhesive stability.
When the water content exceeds 2.6 times, the stability of the adhesive can be maintained, but the suitability for high-speed lamination deteriorates. If the water ratio is lower than 2.3 times water, the adhesive area becomes small, the permanent adhesive strength decreases at the same glue application amount, and it becomes difficult to maintain the viscosity stability.

In the present invention, the M / C ratio needs to be 7-9. As described above, in the SH method, usually,
It has been considered that it is better to increase the carrier ratio in order to increase the M / C to 3 to 6 and to improve the initial adhesive strength.
The present inventors have conducted intensive studies on the initial adhesive strength,
In order to increase the initial adhesive strength, it is not always necessary to increase the carrier ratio. On the contrary, the present inventors have found that the main starch greatly contributes to the initial adhesive strength. In particular, when the M / C ratio was set to 7 to 9, it was found that a good viscosity range and a good water retention were obtained in the formulation of 2.3 to 2.6 times water. If the M / C ratio exceeds 9, the water retention of the adhesive and the Hercules viscosity become too low, causing problems such as insufficient gelatinization of the main starch and insufficient adhesive adhesion due to insufficient water on the corrugator. When the M / C ratio is less than 7, the Brookfield viscosity and Hercules viscosity of the adhesive become too high, and problems such as deterioration of fluidity and excessive adhesion of the adhesive occur.

The water retention of the adhesive in the present invention is 400 g.
/ M ² or less. If it exceeds 400 g / m ² , the amount of water absorbed into the liner and the core becomes too large, and the amount of water required when the main starch is gelatinized is insufficient. Will decrease.

Here, the water retention indicates the ability of the adhesive liquid to retain water, and is defined by KALTEC SCIENTIFIC, I
NC. GRAVIMETRIC WATER RETENTION METER AA-GW
It is measured using R. The measuring method is described below. Several sheets of filter paper (No.
5C), and a polycarbonate film (GWR4 manufactured by KALTEC SCIENTIFIC, INC.) Having a pore of 5 μm thereon.
Place 20). 5cc kept at 30 ℃ in the attached cylinder
And the water retention is measured under the conditions of 0.1 MPa and 100 seconds. In this measurement method, since the amount of water that escapes is measured, the smaller the numerical value, the better the water retention.

The adhesive of the present invention has a Hercules viscosity of 15
It must be in the range of ~ 25 cps. Most of the adhesive applicators used in current corrugators are two-roll coaters, but when the Hercules viscosity of the adhesive exceeds 25 cps, it becomes difficult to control the amount of adhesive applied. Therefore, it is necessary to use an excess adhesive, which is economically disadvantageous. On the other hand, 15
If it is less than cps, the adhesive rolls up poorly, and a required amount of adhesive adhesion may not be obtained.

The Hercules viscosity referred to herein is:
It is a viscosity under a high shear stress measured using a Hercules viscometer, and it is possible to estimate an adhesion amount of an adhesive on a roll coater. The measuring method is as follows.
Put the adhesive kept at 30 ° C into the cup,
Hercules viscometer (HI-SHEAR VISCOMETER HERCULES TYPE manufactured by Kumagai Riki Kogyo Co., Ltd.)
MODEL HRD-801C). 44 using F Bob
The viscosity at 00 rpm was measured and calculated by the following formula. Hercules viscosity (cps) = (range x measured value x 7)
6.4 × 100) / 4400

In the present invention, as the auxiliary, ordinary SH may be used.
Caustic soda and borax used in the method can be used. Caustic soda has the effect of accelerating the gelatinization of the main starch, and is generally added in an amount of about 1.0 to 3.0% by weight based on the starch. Of course, an alkali other than caustic soda may be used. For example, alkali metal hydroxides such as potassium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide, alkaline earth metal oxides such as barium oxide, alkali metal carbonates such as sodium carbonate, and alkalis such as sodium silicate. Metal silicates. The alkali is used in an aqueous solution or solid. Borax has the effect of increasing the stability of the adhesive solution due to its buffer effect, as well as promoting the development of the initial adhesive strength by binding to the gelatinized starch. The amount of addition is generally about 0.2 to 5.0% by weight based on starch. In addition, as other auxiliaries, a bulking agent, a leveling agent, a water retention agent, a plasticizer, a solubilizing agent, a water-proofing agent, and the like can be blended according to the purpose.

The production apparatus used in the present invention is preferably a two-tank type adhesive production apparatus developed by Henry Pratt, but is not particularly limited.

[0022]

The present invention will be described in more detail with reference to the following examples. In the examples, "parts" means "parts by weight", and "%" means "% by weight". The initial adhesion time and sedimentation here were measured by the following methods.

<Initial Adhesion Time> An adhesive is applied on a PET film using a Meyer bar # 50 or # 55, and
NRK280g / m ² the F side liner, reinforcement in the core 2 to the central core
The core of the single-sided cardboard made of the base paper having a thickness of 00 g / m ² is pressed against the adhesive-coated surface to transfer the adhesive to the top of the core. The back surface of the laminating liner (NRK 280 g / m ² ) is placed on a hot plate controlled at 120 ° C., and at the same time, a single-sided cardboard is placed so that the top of the step is in contact with the back of the liner. A weight having a load of 40 g / m ² is placed and left still. Immediately after the lapse of the designated time, the two hands are peeled off, and the degree of peeling is visually determined. The criteria are shown in Table 1 below. The time until the peel strength 4 is obtained is defined as the initial bonding time.

[0024]

[Table 1]

<Sedimentation> 300 ml of the adhesive was placed in a 300 ml measuring cylinder, sealed with aluminum foil and sealed at 20 ° C.
Leave in a 65% atmosphere. After a lapse of 24 hours, the adhesive is withdrawn with a pipette, the thickness of the sediment collected on the bottom is measured, the volume is determined, and the amount of the sediment per 100 ml of the adhesive (ml) is calculated.

Example 1 200 g of carrier starch (OH) was added to 1500 g of water at 60 ° C.
P-C153, manufactured by Oji Cornstarch) and a homomixer (TK AUTO HOMO MIXER,
The mixture was stirred at 3000 rpm for 5 minutes with a specialty machine (manufactured by Tokushu Kika) to obtain a carrier starch dispersion. 31 g of the carrier starch dispersion
Of sodium hydroxide was added and dissolved at 5000 rpm for 20 minutes to obtain a carrier portion. On the other hand, 32 g of borax was dissolved in 2660 g of water at 35 ° C., 1400 g of corn starch (corn starch, manufactured by Oji Corn Starch) was added, and the mixture was stirred at 4700 rpm for 5 minutes with a homomixer to obtain a main part. Further, the carrier portion was dropped into the main portion over 10 minutes while stirring at 5000 rpm with a homomixer. After the addition of the carrier portion, the mixture was further stirred for 10 minutes to obtain an adhesive for cardboard. An evaluation test was performed using this adhesive for cardboard.

Example 2 An adhesive for cardboard was produced in the same manner as in Example 1, and an evaluation test was performed. However, the water in the carrier part was 1123
g, carrier starch 150 g, caustic soda 31.7
g, 2777 g of water in the main part, 30 g of borax, and 1350 g of main starch.

Example 3 An adhesive for cardboard was produced in the same manner as in Example 1, and an evaluation test was performed. However, the water in the carrier part was 1123
g, carrier starch 150 g, caustic soda 31.7
g, the main part water was 2327 g, the borax was 30 g, and the main starch was 1350 g.

Comparative Example 1 An adhesive for cardboard was produced in the same manner as in Example 1, and an evaluation test was performed. However, low-viscosity starch (TR-20, manufactured by Honen Corporation) was used as the carrier starch.

Comparative Example 2 An adhesive for cardboard was produced in the same manner as in Example 1, and an evaluation test was performed. However, the caustic soda of the carrier part is 2
9 g, 2100 g of main part water, 24 g of borax, and 1000 g of main starch.

Comparative Example 3 An adhesive for cardboard was produced in the same manner as in Example 1, and an evaluation test was performed. However, the water in the main part was 3300 g.

Comparative Example 4 An adhesive for cardboard was produced in the same manner as in Example 1, and an evaluation test was performed. However, the caustic soda of the carrier part is 2
9 g, 1620 g of main part water, 24 g of borax, and 1000 g of main starch.

Comparative Example 5 An adhesive for cardboard was produced in the same manner as in Example 1, and an evaluation test was performed. However, the water in the carrier part was 1123
g, carrier starch 150 g, caustic soda 31.7
g, 1877 g of water in the main part, 30 g of borax, and 1350 g of main starch.

Comparative Example 6 An adhesive for cardboard was produced in the same manner as in Example 1, and an evaluation test was performed. However, untreated corn starch (corn starch, manufactured by Oji Corn Starch) was used as the carrier starch.

[0035]

[Table 2]

[0036]

[Table 3]

[0037]

[Table 4]

[0038]

According to the present invention, the water content in the adhesive is reduced while maintaining the viscosity stability of the adhesive in the corrugated cardboard adhesive manufactured by the Steinhole method, and the ratio of the main starch in the starch is reduced. By increasing the adhesive strength, it is possible to obtain an adhesive for corrugated cardboard having improved suitability for high-speed lamination, and its industrial value is extremely large.

Continued on the front page (72) Inventor Saburo Takeyama 2-3-2 Higashishinozaki, Edogawa-ku, Tokyo Oji Paper Co., Ltd. Edogawa Research Center

Claims (1)

[Claims] The present invention relates to an adhesive for cardboard manufactured by the Steinhole method, wherein the water / starch ratio is 2.3 to 2.6, the main starch / carrier starch ratio is 7 to 9, and KALTEC SCIENTIF is used.
GRAVIMETRIC WATER RETENTION METER A manufactured by IC, INC.
The water retention at 30 ° C., 0.1 MPa, 100 seconds by A-GWR is 400 g / m ² or less, and the viscosity at 30 ° C., 4400 rpm, F bob using a Hercules viscometer is 1
An adhesive for corrugated cardboard, wherein starch having a Brookfield viscosity at 50 ° C. of 300 to 1000 cps at 50 ° C. is used as a carrier starch in a range of 5 to 25 cps and a carrier liquid starch having a concentration of 11.5% by weight.