JPH05163471A - Preparation of paste liquid and compounded product for paste liquid - Google Patents

Abstract

PURPOSE:To obtain a paste liquid having a constant viscosity and pH, remarkably improved viscosity stability as compared with that of conventional paste liquids and hardly any dispersion by adding a specific principal agent for reducing the viscosity in thermally gelatinizing an aqueous starch suspension. CONSTITUTION:An aqueous suspension of starch is thermally gelatinized. In the process, a basic peroxide (e.g. sodium peroxocarbonate) as a principal agent for reducing the viscosity in an amount of preferably 2-3.5 pts.wt. based on 100 pts.wt. starch is added to the aqueous suspension to afford a paste liquid. When the thermal gelatinization is carried out by a batch method, treatment is usually conducted under heating conditions of 90-110 deg.C for 20-60min. In the case of a continuous method, the treatment is usually carried out under heating conditions of 110-170 deg.C for 0-20min. Furthermore, an acidic substance such as a peroxo acid salt is preferably added as an assistant for treatment to reduce the viscosity from the viewpoint of storage stability of the paste liquid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preparing a paste solution by heating and gelatinizing an aqueous suspension of starch, and a paste solution preparation used therein.

The glue liquid prepared by the method of the present invention or from the paste liquid preparation of the present invention is suitable as an adhesive (including a binder and a sizing agent) for papermaking, corrugated board and fibers.

In the following description, a compounding unit is a weight unit unless otherwise specified.

[0004]

2. Description of the Related Art Generally, a paste solution used as an adhesive is required to have a high solution concentration and a low viscosity. Therefore, it is necessary to reduce the viscosity of the paste solution.

As a method for reducing the viscosity, there is a method of adding various viscosity reducing agents to starch when gelatinizing an aqueous suspension of starch by heating. That is, a method of using ammonium peroxodisulfate as a viscosity reducing agent (see Comparative Examples 1 and 4) and a method of using a nitrogen compound and an acidic substance in combination (JP-A-60-28475, JP-A-61-174244, JP-A-61-174244). 62-6766) (see Comparative Examples 2, 3, 5, and 6) and a method using a starch-degrading enzyme (see Comparative Example 7).

[0006]

However, as a result of the tests and examinations conducted by the present inventors, the glue liquid prepared by each of the above methods was
We found the following problems.

It is difficult to prepare a paste solution having a constant viscosity with little variation.

The viscosity tends to change with time due to aging and decomposition of starch (the viscosity stability of the paste solution is not good).

Sizing degree (Stechit / Sizing degree: JIS
P 8122) is lower than that of modified starch.

The present invention is to provide a method for preparing a paste solution and a preparation for a paste solution which can solve the above problems.

[0011]

Means for Solving the Problems As a result of intensive efforts for development to solve the above problems, the present inventors have conceived a method for preparing a paste solution and a preparation for a paste solution having the following constitution.

The method of preparing a paste solution according to claim 1 is characterized in that a basic peroxide is added as a viscosity reducing treatment main agent when the starch aqueous suspension is gelatinized by heating.

According to a second aspect of the present invention, there is provided a method of preparing a paste solution, wherein, when gelatinizing an aqueous suspension of starch by heating, a basic peroxide is used as a viscosity reducing treatment main agent and an acidic substance is used as a viscosity reducing treatment auxiliary agent. Is added respectively.

A paste liquid preparation according to claim 3 is characterized in that solid basic peroxide as a viscosity reducing treatment agent is added to starch.

According to a fourth aspect of the present invention, there is provided a paste liquid preparation, which comprises starch, a basic peroxide as a main agent for lowering viscosity, and
It is characterized in that an acidic substance is added as a viscosity reducing treatment aid.

[0016]

Detailed Description of Means Each constituent element of the present invention will be described below.

(I) Starch: Starch as a raw material is corn starch, waxy starch, high amylose starch,
It is desirable that unmodified starch such as potato starch, tapioca starch, sago starch, wheat starch, and the like, which can be easily and inexpensively obtained, such as various powdered grains containing starch such as corn flour and wheat flour as a main component.

Although not desirable in terms of cost, starch derivatives such as acetylated starch, hydroxyethylated starch, and cationized starch obtained by introducing a substituent into the above-mentioned starch by a known method, mild oxidation treatment or mild acid treatment. Treated oxidized starch, acid-treated starch, starch subjected to radiation treatment, wet heat treatment, heat treatment and the like can also be used.

(Ii) Basic peroxide: The basic peroxide is
When it is made into an aqueous solution, it means that it exhibits alkalinity exceeding pH 7.0, and has the function of decomposing starch under non-acidic conditions, that is, it becomes the base agent for the viscosity reduction treatment of paste solutions.

In the case of the paste formulation according to claims 3 and 4, it is limited to a solid form in order to prevent deterioration of the starch powder when mixed with the starch. The blending amount of this basic peroxide with respect to the starch depends on the type of starch used in the formulation, the target viscosity of the paste, and the pH.
Generally, 1 to 100 parts of starch varies depending on
6 parts (preferably 2 to 3.5 parts).

Specifically, sodium peroxocarbonate,
Solid forms of sodium peroxoborate, potassium peroxocarbonate, potassium peroxoborate, potassium peroxodiphosphate, etc. can be used, but in the case of claims 1 and 2, liquid forms of these with a solvent, and further hypochlorite Liquid substances such as acid soda can also be used.

(Iii) Acidic substance: Weakly acidic means that when it is made into an aqueous solution, it exhibits an acidity of less than pH 7.0, and has an action of increasing or complementing the starch decomposing action of the above basic peroxide. In addition to being responsible (becomes a processing aid for lowering viscosity), it is also responsible for adjusting the pH of the paste solution.

In the case of the paste liquid preparation of claim 4, the acidic substance is limited to a solid one in order to prevent deterioration of the starch when mixed with the starch, like the basic peroxide. To be done. The amount of the acidic substance blended varies depending on the type of starch used for preparation, the target viscosity and pH of the paste solution, but is usually 0.05 to 1 part (desirably, 100 parts of starch).
0.1 to 0.5 part).

As the acidic substance, the following solid peroxo acid salts, organic acids, ammonium salts, and pyrophosphoric acid can be used.

Ammonium peroxodisulfate, potassium peroxodisulfate, sodium peroxodisulfate, sodium peroxomolybdate, potassium peroxomolybdate, etc.

Maleic acid, sulfamic acid, etc., ammonium sulfate, ammonium chloride, ammonium nitrate, etc.

Further, in the case of claim 2, it is possible to use a liquid form of the above chemical agent, and a liquid form of sulfuric acid, orthophosphoric acid, acetic acid or the like.

(Iv) In claims 1 and 2, when the starch is heated to gelatinize the aqueous suspension, the addition timing and the addition order of the viscosity-reducing main agent and auxiliary agent are not limited. is not. That is, regarding the timing of addition, during heating and gelatinization of the aqueous suspension in the state of starch powder,
After heating and gelatinizing, any of the above can be carried out in a state of being kept at a high temperature, and the above-mentioned main agent / auxiliary agent may be added simultaneously or separately.

The heating gelatinization method may be either a batch method or a continuous method (using a jet cooker, an oner, etc.). The heating conditions are the type of starch and the target viscosity of the paste.
It depends on the pH, but usually 90-
110 ° C x 20-60 min, 110-in case of continuous system
170 ° C x 0 to 20 min.

In the preparation of the gelatinization of the present invention, water-soluble polymer, antiseptic, antiaging agent, dye, pigment and the like may be appropriately added. As the water-soluble polymer, polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), sodium alginate, etc. can be used.

(V) The paste liquid preparations according to claims 3 and 4 are produced by a batch type mixer (kneader, ribbon blender, air blender, rocking mixer, etc.) or a continuous type mixer (flash mixer, cokneader, etc.). A method of uniformly mixing the above-mentioned solid viscosity-reducing main agent / auxiliary agent with the starch to be used for packaging, or a packaging container such as a paper bag or a flexible container filled with a certain amount of starch, and The vulcanization treatment main agent / auxiliary agent is unevenly distributed (in a state where they do not contact each other) and filled into a product.

The method for preparing a paste solution from these paste preparations can be appropriately selected from the methods described in (iv) above.

[0033]

EFFECTS OF THE INVENTION The method for preparing a paste solution and the preparation for a paste solution according to the present invention have the following effects supported by the examples described later.

That is, not only a paste solution having a constant viscosity and pH can be prepared with little variation but also a viscosity stability far superior to that of a paste solution prepared by a conventional inexpensive viscosity-lowering method, It shows the same degree of size as starch.

The paste solution preparations according to claims 2 and 3 are also excellent in storage stability in a paper bag or the like.

The sizing solution prepared by the process according to the invention or from the sizing solution preparation is therefore particularly suitable as an ordinary adhesive, of course, in particular for surface size and coating in the paper industry.

[0037]

EXAMPLES Examples and comparative examples conducted to confirm the effects of the present invention will be described below.

[0038] (1) Examples and Comparative Examples corresponding to claim 1, 2: Aqueous suspension of a 25% strength containing a (Examples 1-3 and Comparative Examples 1) corn starch 60 g (anhydrous basis) After being prepared, the indicated number of parts (for 100 parts of starch) of each viscosity reducing treatment agent was added to the suspension. Add this to the autoclave 240
g, and the suspension temperature was raised to 110 ° C. with stirring. And it maintained at the said temperature and stood still for 20 to 40 minutes.

In Comparative Example 1, the paste solution was adjusted to pH 8.5 with a 5% sodium hydroxide solution.

<Test Items / Results and Evaluation> For each paste solution thus prepared, 10% concentration, 50 ° C. viscosity / pH
Was measured and the color was visually observed. From the test results shown in Table 1, the effect of addition is clear in each of the examples in which the basic peroxide was used as the base agent for lowering the viscosity.

That is, the acidic substance not only acts as a viscosity-reducing treatment auxiliary agent, but also has a pH-adjusting action, and the pH is such that the viscosity of the paste solution does not substantially decrease. There is. The viscosity of the paste solution is constant regardless of the heating time.

(2) Example corresponding to claims 3 and 4 (included in claims 1 and 2): (Example 4) After mixing 100 parts of corn starch and 3.0 parts of sodium peroxoborate in a rocking mixer It was sealed in a 25 kg paper bag and stored under normal temperature and pressure. 1 to
After 6 days, the paste solution is taken out of the paper bag to make 1 m ³ of 10% starch suspension. This suspension was supplied to a continuous cooking device (manufactured by Nippon Corn Starch Co., Ltd.) at a flow rate of 10 l / min, the liquid temperature was instantly raised to 145 ° C. through high-pressure steam, and the liquid was held and retained in the holding tube for 6 minutes to reduce the temperature. It was thickened and gelatinized.

Example 5 100 parts of corn starch, 2.5 parts of sodium peroxoborate and 0.2 parts of ammonium peroxodisulfate were mixed in a rocking mixer, sealed in a 25 kg paper bag and stored at room temperature and atmospheric pressure for 4 months. Then, remove the paste formulation from the paper bag 25
A starch suspension (1 m ³⁾ having a concentration of 1% was prepared, and the viscosity reduction and gelatinization were performed in the same manner as in Example 4.

(Embodiment 6) The mixing ratio is cornstarch 1
Example 5 is the same as Example 5 except that the amount is 00 parts, sodium peroxoborate 2.5 parts, and sulfamic acid 0.35 parts.

(Embodiment 7) The mixing ratio is cornstarch 1
Example 5 is the same as Example 5 except that the amount is 00 parts, sodium peroxocarbonate 2.5 parts, and ammonium peroxodisulfate 0.2 parts.

(Example 8) The compounding ratio was cornstarch 1
Example 5 is the same as Example 5 except that the amount is 00 parts, sodium peroxoborate 2.5 parts, sodium peroxodisulfate 0.1 parts, and sulfamic acid 0.2 parts.

(Example 9) The mixing ratio was cornstarch 1
Example 5 is the same as Example 5 except that the amount is 00 parts, sodium peroxoborate 2.5 parts, and ammonium sulfate 0.4 parts.

Comparative Example 2 A starch suspension (25% concentration) was prepared using cornstarch, and ammonium peroxodisulfate was added to the starch suspension to give a starch content of 0.3%, and a low viscosity was obtained under the same conditions as in Example 5. And gelatinized. Then, the acidic paste solution was adjusted to pH 8.5 with a 5% sodium hydroxide solution.

(Comparative Example 3) A starch suspension (25% concentration) was prepared using cornstarch, to which 0.3% sulfamic acid and 2.0% urea for starch were added, and the same conditions as in Example 5 were applied. To lower the viscosity and gelatinize.

(Comparative Example 4) A starch suspension (25% concentration) was prepared using corn starch, to which 0.3% ammonium peroxodisulfate and 2.0% urea based on starch were added.
The viscosity reduction and gelatinization were performed under the same conditions as in Example 5.

(Comparative Example 5) 2 using cornstarch
After making a 5% starch suspension (adjusted to pH 4.5) and adding 0.03% of α-amylase to starch, the starch suspension was stirred at 95 ° C under the condition of 1.5 ° C / min. The temperature was raised up to low viscosity and gelatinization. After that, the paste solution is concentrated to 8
% And diluted with 5% sodium hydroxide solution to pH 8.5
Adjusted to.

<Test Items / Results and Evaluation> (i) Each paste solution obtained above was prepared at a concentration of 8% with hot water at 60 ° C. and kept at 50 ° C. immediately after the preparation and 1.4
After 24 hours, each viscosity and pH were measured. From the test results shown in Table 2, it can be seen that each example of the present invention has excellent viscosity stability.

Regarding the relationship between the paste solution preparation of Example 4 and the storage period (1, 3 and 6 months), the paste solution was prepared in the same manner and the viscosity and pH were measured. The result is 1
・ Viscosity is 50.47 for 3 and 6 months respectively.
・ 49cPs and pH were 6.5 ・ 6.5 ・ 6.5. It can be seen that the storability in the paper bag is also good.

(Ii) Further, using the paste solutions of Example 4 and Comparative Examples 2 and 3, and the paste solutions of oxidized starch (commercially available products widely used as modified starch for surface size), The surface size was measured by a test size press (made by Kumagai Riki Co., Ltd.) using unsized medium quality paper. Then, the Steckigt sizing degree of each surface-sized paper was measured according to JIS P 8122. From the measurement results shown in Table 3, it can be seen that the sizing liquids of the examples of the present invention can impart a sizing degree equivalent to that of modified starch to paper. It can be seen that the size of the paste solution prepared by the conventional method is significantly reduced.

[0055]

[Table 1]

[0056]

[Table 2]

[0057]

[Table 3]

Claims (4)

[Claims] 1. A method for preparing a paste solution, which comprises adding a basic peroxide as a viscosity-reducing main agent when gelatinizing an aqueous suspension of starch by heating. 2. A paste characterized by adding a basic peroxide as a viscosity reducing treatment main agent and an acidic substance as a viscosity reducing treatment auxiliary agent when gelatinizing an aqueous suspension of starch by heating. Liquid preparation method. 3. A paste liquid preparation, characterized in that a solid basic peroxide is added to starch as a viscosity reducing treatment main agent. 4. A paste characterized in that a solid basic peroxide as a main agent for lowering viscosity and a solid acidic substance as an auxiliary agent for lowering viscosity are added to starch. Liquid preparation.