JPS6256883B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a hydroxyalkyl ether of galactomannan.

Galactomannan is a neutral polysaccharide consisting of a main chain consisting of mannose as a constituent unit and galactose units as side chains, and is mainly contained in large amounts in the seeds of leguminous plants in nature. In particular, guar gum made from guar beans and locust bean gum made from locust beans are representative vegetable gums containing galactomannan as a main component.

In particular, in the present invention, substances whose main component is galactomannan, including guar gum and locust bean gum, are collectively referred to as galactomannan. These plant gums are plant mucilage substances that dissolve in water and exhibit extremely high viscosity, and are therefore widely used in the food and industrial fields. However, when these galactomannans are made into an aqueous solution, they tend to cause agglomeration of powder particles called "mamako", and aqueous solutions of galactomannans are susceptible to attack by bacteria and deteriorate over time, causing a decrease in their viscosity. It has

The present inventors conducted research and arrived at the present invention with the aim of obtaining a modified galactomannan that has the above-mentioned drawbacks improved while maintaining the extremely high viscosity that is characteristic of galactomannan aqueous solutions.

The hydroxyalkyl ether of galactomannan obtained by the present invention reduces the viscosity change over time of an aqueous solution caused by bacteria without impairing the nonionic properties inherent in galactomannan, and can reduce the viscosity of an aqueous solution with a pH of 12 or less. It also has the property of being stable and maintaining a high aqueous solution viscosity even in the presence of high concentrations of various salts containing multivalent ions. Due to these characteristics, the hydroxyalkyl ether of galactomannan obtained by the present invention is mainly used in paper manufacturing,
It is used in industrial fields such as cosmetics, paints, civil engineering, architecture, petroleum, and explosives.

Conventionally developed methods for hydroxyalkyl etherification of galactomannan include an aqueous medium method using water as a reaction medium and a suspension method in which galactomannan is suspended in a mixture of water and an organic solvent. The suspension method is said to be more advantageous than the aqueous method. This advantage of the suspension method is particularly due to the fact that the reaction system in the hydroxyalkylation process of galactomannan is carried out in the form of suspension and dispersion with extremely low viscosity, and that the process of neutralization and purification after the completion of the hydroxyalkylation reaction is This is due to the fact that the treatment process is easier than the aqueous method. Therefore, among these reasons, if a post-treatment step is unnecessary and the hydroxylation reaction of galactomannan can be carried out under high viscosity, it can be carried out without using an expensive hydrophilic organic solvent. This makes it possible to hydroxyalkylate galactomannan using an aqueous method, which is advantageous over suspension methods, such as eliminating the need for recovery equipment for organic solvents. Therefore, there is a strong desire in the industry to establish a method for hydroxyalkylation that has good reactivity in a highly viscous alkaline solution using water as a medium and does not require post-treatment. Since galactomannan dissolves in water or hot water and exhibits an extremely high viscosity, it is a difficult technique to prepare a highly concentrated and uniform solution without causing galactomannan agglomeration. They found that the solubility of galactomannan in water changes depending on the hydrogen ion concentration of the water, and that a large amount of galactomannan is easily dissolved in a highly alkaline aqueous solution, especially when using a forced stirring mixer such as a kneader. It has been found that by using this method, even larger amounts of galactomannan can be uniformly dissolved without forming "mako". By discovering such a dissolution method, the present inventors have been able to reduce the amount of aqueous medium necessary for the hydroxyalkyl etherification of galactomannan without any reduction in the efficiency of the etherification reaction, and the subsequent drying of the product. The present invention has been completed, which makes it possible to reduce the drying load associated with drying.

The gist of the present invention is a method for producing a hydroxyalkyl ether of galactomannan, which comprises reacting a mixture of galactomannan, a basic substance and water with alkylene oxide under high-speed stirring and drying.

One of the features of the present invention is that the neutralization and purification steps after the completion of the hydroxyalkylation etherification reaction of galactomannan, which were performed in the conventional technology, are omitted, and a method is adopted in which drying is performed directly after the completion of the hydroxyalkyl ether reaction. It is. Conventionally, in post-treatment, it was necessary to first neutralize the strong alkali necessary for the hydroxyalkyl etherification reaction of galactomannan, as it was undesirable for this strong alkali to be mixed into the product. The salt produced during the process tends to remain in the product as ash.
It is undesirable for a large amount of ash to remain in the hydroxyalkyl ether of galactomannan used as the viscous substance. Conventionally, inorganic acids and organic acids have been used to neutralize alkaline substances, but in particular, when inorganic acids are used, the ash content in the product increases, which is why organic acids are often used. Neutralization with a stoichiometric amount of organic acid corresponding to the alkaline substance did not sufficiently neutralize the product, resulting in an alkaline product that was difficult to handle.

Another feature of the present invention is that the present inventors conducted studies in view of the current situation and found that the hydroxyalkyl etherification reaction of galactomannan proceeds satisfactorily even under weak alkalinity. By employing such a hydroxyalkyl etherification reaction under a weak alkali, it is possible to eliminate the neutralization step after the completion of the reaction, which was considered to be impossible in conventional methods, and the reaction process itself can be simplified. At the same time, it was possible to prevent the formation of salts, which would cause undesirable ash content to be mixed into the product.

The form of galactomannan used in carrying out the present invention may be in the form of so-called splits obtained by coarsely pulverizing beans, or may be in the form of finely pulverized powder. Furthermore, powdered galactomannan purified with ether, alcohol, benzene, etc. may also be used. Furthermore, galactomannan whose molecular weight has been reduced by undergoing operations such as thermal decomposition, oxidative decomposition, enzymatic decomposition, and acid hydrolysis can also be used.

The alkylene oxide used in carrying out the present invention is a lower alkylene oxide, and
For example, ethylene oxide, propylene oxide, 1,2-butylene oxide, phtadiene monooxide, glycide, etc. can be used in the reaction regardless of whether they are in gaseous or liquid form, and they must be added to the reaction system in advance before the reaction. It is also possible to add the entire amount to the reaction system sequentially. The amount of alkylene oxide used can be arbitrarily changed depending on the required degree of modification of galactomannan, but it is preferably between 0.01 mol and 6 mol, particularly between 0.1 mol and 2 mol, per anhydrosaccharide unit of galactomannan. be. The reaction is usually carried out at 30°C to
The reaction time is preferably 2 to 24 hours, preferably 2 to 24 hours, which is sufficient to achieve the desired degree of modification.

Basic substances used in carrying out the present invention include alkali metal hydroxides, alkaline earth metal hydroxides, ammonia, organic amines, quaternary ammonium compounds, and water-soluble inorganic salts consisting of strong bases and weak acids. etc. can be used. If large amounts of inorganic salts are mixed into the hydroxyalkyl ether of glactomannan, which is prepared using water-soluble inorganic salts consisting of a strong base and a weak acid among the above basic substances, they will act as ash, so the amount used should be minimized. It is necessary to reduce it. Many alkali metal hydroxides and alkaline earth metal hydroxides themselves exhibit strong basicity, and compared to other basic substances, a satisfactory product can be obtained with a small amount of use; however, if an excessive amount is used, In this case, since the process of the present invention does not involve neutralization or purification of the reaction system, the product becomes alkaline and the viscosity of the aqueous solution rapidly decreases, so it is important to be careful about the amount used. It becomes necessary. Ammonia, organic amines, and quaternary ammonium salts allow the reaction to proceed well, and they volatilize from the raw product in the process of immediately drying the product after the reaction is completed, so these organic amines must be recovered. It also has the advantage of being reusable. Furthermore, even if these substances are mixed into the obtained product, they do not cause ash content and do not significantly reduce the viscosity of the aqueous solution, so they are particularly preferred.

The present invention uses a method in which alkylene oxide is reacted in a mixed solution of galactomannan and water, which causes non-uniformity of the reaction in normal methods, but in the present invention, this mixed solution Since this is carried out under high-speed stirring, the above-mentioned heterogeneous reaction does not occur. Usable reaction devices include atmospheric reflux type containers, pressure stirring vessels, pressure kneaders, pressure blenders, etc., but the use of pressure kneaders and pressure blenders that can forcefully stir the reaction system is particularly effective. results.

In the present invention, a method can be employed in which the reaction product obtained by the reaction as described above is dried without being subjected to any treatment such as neutralization or purification, so that the process can be significantly simplified. For example, a method of casting the reaction product to form a film, drying it and then pulverizing it, or drying it with a drum dryer,
A method such as extrusion drying as a thin layer using a die may be adopted.

The method of the present invention uses a system in which galactomannan and alkylene oxide are reacted under forced stirring, so that the reaction system can be highly concentrated, the reaction product can be dried in the form of a film, and the process is extremely simple. The process is simple, and by conducting the reaction under a weak alkali, the process of neutralizing the system after the completion of the reaction can be omitted. This made it possible to reduce the amount of ash contamination that degrades the properties of the product.

The present invention will be explained in more detail with reference to Examples below.

Example 1 An aqueous solution of 8 g of sodium hydroxide dissolved in 400 ml of water and 500 g of guar gum powder with a moisture content of 12% were added to a pressurized sealed kneader with an internal volume of 3 until "mamako" and aggregates were no longer observed. Practice. After that, the kneader was sealed and sealed with nitrogen, the kneader was heated to 80°C, 150g of propylene oxide was gradually added, and the reaction was carried out for 4 hours.The kneader was then cooled to room temperature, replaced with nitrogen again, and the contents were poured out. I took it out. The reaction product was formed into a thin plate and dried in a vacuum dryer at 70°C for one day and night. Thereafter, it was crushed to obtain guar gum hydroxypropyl ether with a moisture content of 11% and an ash content of 3.0%.

Example 2 Add 500 ml of water and 500 g of guar gum powder with a moisture content of 12% to a pressurized closed kneader with an internal volume of 3, close the reactor, seal with nitrogen, and add diethylamine.
Add 20g and stir at room temperature for 2 hours. Thereafter, the reactor was heated to 60° C., and 75 g of ethylene oxide was gradually added to carry out the reaction for 8 hours. Thereafter, the reactor was cooled to room temperature and replaced with nitrogen, and then the reaction product was taken out. This reaction product was formed into a thin plate, dried in a vacuum dryer at 70°C for one day and night, and then pulverized to obtain guar gum hydroxyethyl ether having a moisture content of 8% and an ash content of 1.6%.

Example 3 30 g of triethylbenzylammonium chloride, moisture content 10, in a pressurized closed kneader with an internal volume of 3.
% locust bean gum powder 500g and water 500ml
Prepare and knead at a temperature of 80℃ until "mamako" and aggregates are no longer visible. Thereafter, the inside of the reactor was purged with nitrogen, 75 g of propylene oxide was gradually added, and the reaction was carried out for 8 hours. Thereafter, the kneader was cooled to room temperature and the reaction product was taken out.
The reaction product was formed into a thin plate and dried in a vacuum dryer at 70℃ for one day and night, and then ground to a moisture content of 10% and an ash content.
1.9% locust bean gum hydroxypropyl ether was obtained.

Claims (1)

[Claims] 1. A hydroxyalkyl ether of galactomannan, which is characterized in that the reaction product obtained by reacting a mixture of galactomannan, a basic substance, and water with an alkylene oxide under high-speed stirring is directly dried. Production method. 2 Ammonia organic amine No. 4 as a basic substance
The method for producing a hydroxyalkyl ether of galactomannan according to claim 1, characterized in that a substance selected from class ammonium compounds is used. 3. The method for producing a hydroxyalkyl ether of galactomannan according to claim 1, characterized in that the drying method is carried out with the reaction product formed into a thin molded product.