JPS5996103A - Method for producing hydroxyalkyl ether of galactomannan whose aqueous solution has excellent transparency - Google Patents

Abstract

PURPOSE:To obtain the titled hydroxyalkyl ether, by reacting galactomannan with an alkylene oxide in the presence of an alkali metal hydroxide by using a medium consisting of a hydrophilic organic solvent and water. CONSTITUTION:Galactomannan is reacted with an alkylene oxide in the presence of at least 0.4mol, per anhydrosugar unit of galactomannan, of an alkali metal hydroxide, by using a medium consisting of a hydrophilic organic solvent and water. Said solvent refers to an organic solvent of such hydrophilicity that it will not separate from water when it contains at least 30wt% water, and preferable examples of the solvents include 2-propanol, acetone, and methyl ethyl ketone. The ratio of the hydrophilic solvent to water is preferably in the range of 30:70-95:5. Galactomannan which can be used includes a galactomannan- based substance such as guar gum or locustbean gum, and raw materials for these gums, such as guar beans or locust beans.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a hydroxyalkyl ether of galactomannan whose aqueous solution has excellent transparency.

Galactomannan is a neutral polysaccharide composed of a main chain consisting of mannose as a constituent unit and galactose units as side chains. Locust bean λ made from locust bean and locust bean are representative vegetable gums containing galactomannan as a main component.

These plant gums are plant mucilage substances that exhibit extremely high viscosity when dissolved in water, so they are widely used in the food and industrial fields8. However, when galactomannan is made into an aqueous solution, Galactomannan aqueous solutions are easily attacked by bacteria, deteriorate over time and cause a decrease in viscosity, and the aqueous solution becomes cloudy.

Conventionally, as a method for producing a hydroxyalkyl ether of galactomannan, a method is known in which galactomannan is reacted with glycerin monohalohydrin in the presence of an alkali and using water as a medium (see US Pat. No. 2,496,670).

However, according to additional tests conducted by the present inventors, it was found that this method has the following drawbacks. First of all, when the resulting product is made into an aqueous solution, although it has slightly better transparency than galactomannan, excellent transparency cannot be obtained.

Second, since the reaction uses water as a medium, galactomannan and the reaction product are dissolved in water, making it extremely difficult to control the process, such as stirring, transportation, and drying.

Further, US Pat. No. 3'32689 [1] describes a method for producing a hydroxyalkyl ether of galactomannan by the IL-Shu method using an organic amine and a quaternary organic ammonium hydroxide as an alkaline reagent. . However, this method has a slow reaction rate between alkylene oxide and /j lactomannan, and usually
When the reaction time is about 8 hours, the effective utilization rate of alkylene oxide to galactomannan is as low as 40% or less, which poses a problem in terms of economic efficiency. In addition, MS (
The number of moles of alkylene oxide added per anhydrosaccharide unit was less than 0.1i, which was insufficient and the product was unsatisfactory. Furthermore, there is a drawback that a large amount of unreacted etherification reagent remains after the reaction.

In view of these circumstances, the present inventors have conducted extensive research to obtain a hydrohen alkyl ether of galactomannan whose aqueous solution has excellent transparency! ,
1/ As a result, the present invention has been achieved.

The present invention provides galactomannan with 0.0% per anhydrosaccharide unit of galactomannan. -4 moles or more of alkali gold (
, i: A method for producing a hydroxyalkyl ether of galactomannan whose aqueous solution has excellent transparency, which is characterized by reacting it with an alkylene oxide in the presence of a hydroxide in a hydrophilic organic solvent and water as a medium. .

The present invention has a major feature in that all reactions proceed with galactomannan being suspended and dispersed in the medium.

Therefore, operations such as intermediate phase, washing, and purification after completion of the reaction can be facilitated, and operation and maintenance can be facilitated.

The hydroxyalkyl ether of galactomannan, which has excellent transparency in an aqueous solution 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.
The viscosity of the aqueous solution is stable at a pH of 12 or less, and the viscosity of the aqueous solution can be maintained at a high level even in the presence of high concentrations of various salts containing multivalent ions.

As the galactomannan, substances containing galactomannan as a main component such as guar gum and locust bean gum, and their raw materials such as guar beans and locust beans can also be used.

Galactomannan Imaya ≠ Toji is a so-called split type made by coarsely crushing legumes, and finely crushed (pulverized powder) can also be used. Also used are products purified by methods such as thermal decomposition, oxidative decomposition, enzymatic decomposition,
Galactomannan whose molecular weight has been lowered by performing operations such as acid hydrolysis can also be used.

Hydrophilic organic solvent refers to an organic solvent that contains at least 60% by weight of water and does not separate from water (-means an organic solvent that does not easily react with galactomannan, alkali metal hydroxides, or alkylene oxides).1. It is preferable that there is a typical hydrophilicity (41fl i(, Q Yi
Examples of the agent include alcohols such as methanol, ethanol, propanol and butanol, ketones such as acetone and methyl ethyl ketone, and mixtures thereof, preferably 2-propanol, tert-butanol, acetone, methyl ethyl ketone, etc. Can be mentioned.

The ratio of the hydrophilic organic solvent as the reaction medium to water is preferably in the range of 30:0 to 95:5 by weight. .

When the proportion of water in the reaction medium decreases below 5% by weight, the reaction rate of hydroxyalylization of galactomannan decreases markedly and the reaction hardly proceeds. Further, the amount of alkylene oxide remaining in the reaction solution after the reaction becomes extremely large, which is not preferable. As the proportion of water increases,
11 reaction degree increases, it becomes possible to obtain good reaction conditions, and alkylene oxide residue remaining in the reaction solution after the reaction is also reduced. Furthermore, the effective utilization rate of alkylene oxide is increased, and a high rate of 80% can be achieved.

When the proportion of water in the reaction medium increases beyond 70% by weight, the hydroxyalkyl ether of galactomannan produced does not remain suspended in the medium but dissolves, resulting in thickening of the entire reaction system. As a result, it becomes impossible to maintain the slurry state and continue the reaction, which makes it difficult to efficiently perform post-processing steps such as separation and purification of reaction products, resulting in extremely poor operability in post-processing steps. .

Generally, as the ratio of hydrophilic organic solvent 9 to water increases, the transparency of the aqueous solution of the reaction product increases, and the reaction can proceed in a stable suspension state.

As the alkali metal hydroxide, sodium hydroxide, potassium hydroxide, etc. may be used. The amount of alkali metal hydroxide added is 0.4 mol or more per anhydrosaccharide unit of galactomanlaan.

In the hydroxyalkyl reaction process of galactomannan, the role of the alkali metal hydroxide is as a catalyst, and the reaction proceeds even if the amount added is small. However, when the amount of alkali metal hydroxide added is less than 0.4 mol per anhydrosaccharide unit of galactomannan, the resulting aqueous solution of hydroxyalkyl ether of galactomannan is less cloudy than the fountain solution of galactomannan itself. , it is still not transparent.

On the other hand, the amount of alkali metal hydroxide added is preferably 6 mol or less per anhydrosaccharide (Q). If the amount added is greater than this, there is a risk that the galactomannan slurry will aggregate during the reaction.

For example, Impro Kunor 450 as reaction medium
When parts of 'fJ and 220 parts by volume of water are used, if 20 parts by weight of sodium hydroxide is added to 100 parts by weight of guar gum, agglomeration will occur, which is not preferable. However, when 15 parts by weight of sodium hydroxide is added, agglomeration can be prevented by stirring.Agglomeration can also be prevented by increasing the proportion of the hydrophilic organic solvent. .

Examples of the alkylene oxide include lower alkylene oxides such as ethylene oxide, propylene oxide, 1,2-butylene oxide, butdiene monooxide, and glycide. The alkylene oxide can be used in either gaseous or liquid form, and the entire amount may be charged before the reaction, or it may be added to the reaction system sequentially.

The amount of alkylene oxide used can be arbitrarily changed depending on the degree of modification of galactomannan;
Particularly preferred is 0.1 to 4 mol.

When carrying out the present invention, an alkali metal hydroxide, water and a hydrophilic organic solvent r'+ll are also added to the galactomannan.
＋111 and mix) to prepare a dispersion liquid.

Al, IJ IJ Gold 1. - It is preferable to add 11-hydroxide as an aqueous solution. For this purpose, all or part of a predetermined amount of water is used to prepare an alkali metal hydroxide solution, and after suspending and dispersing galactomannan in a hydrophilic organic solvent or a mixture of this and water, Preferably, an oxide solution is added.

Next, a hydroxyalkyl ether is added to this suspension dispersion and reacted. The reaction is usually carried out between 60 and 100°C. The reaction time is sufficient to achieve a predetermined degree of modification (MS), and is preferably 2 to 24 hours. The form of the reaction vessel may be any one such as a normal pressure reflux type vessel, a pressurized stirring vessel, a pressurized kneader-1 pressurized blender, etc.

After the reaction is completed, the reaction product is neutralized, filtered, washed with an aqueous solution of a water-soluble organic solvent, and then dried and ground to obtain a product.

According to the method of the present invention, since the reaction proceeds while the galactomannan and its reactants are suspended in water and a water-soluble organic solvent, operations after the completion of the reaction can also proceed in the suspended state. Therefore, process control becomes easy and products of excellent quality can be manufactured efficiently. Also, US Patent 2
Compared to the method described in No. 496,670, a larger amount of galactomannan can be processed using the same volume of reaction vessel.

The hydroxyalkyl ether of galactomannan produced by the method of the present invention is particularly useful in the fields of coatings, paints, fibers, rubber, cosmetics, paper manufacturing, and the like.

A more detailed explanation will be given in the Examples below, but the transparency shown in the Examples and Comparative Examples was measured by the following method.

A sample is added to the distilled water while vigorously stirring it with a homogenizer to prepare a 1% by weight aqueous solution of the sample on an absolute dry basis, which is defoamed in a vacuum desiccator and left overnight. On the other hand, using a self-made white light transparency measuring device that was a modification of the Hitachi visible light spectrophotometer model 101 and a concave reflector installed in the prism spectrometer section, a sample aqueous solution was poured into a glass cell with an optical path length of 10 zones. The transparency was expressed as a percentage of transmittance with reference to the light transmitted through distilled water from the same cell.

Example 1 2-Propatool 400 was placed in a four-loaf flask with an internal volume of 1e equipped with a stirrer, a condenser, a dropping funnel and a thermometer.
ml, 6 ml of water (3 ml and 6 ml of guar gum powder with a moisture content of 12%)
0 g was added and stirred to form a uniform suspension and dispersion. 3. Sodium hydroxide is gradually added to this dispersion through a dropping funnel. !
A sodium hydroxide solution prepared by dissolving 9 in 50 mt of water was added dropwise at room temperature, and after stirring at room temperature for 1 hour, propylene oxide 55& was added dropwise from the dropping funnel and the entire flask was heated to 80°C in a hot water bath. Continue the time reaction.

After the reaction is completed, the inside of the flask is cooled to 65° C. or below, and glacial acetic acid is gradually added dropwise from the dropping funnel while stirring to neutralize the flask. The reaction system is kept in a good suspended state throughout the entire reaction process. The reaction product was then filtered and further 80% 2-
After washing with 200 ml of propatool aqueous solution, it is filtered again and further washed with 150 ml of 2-propanol, and then the reaction product is taken out and dried in a vacuum dryer at 70° C. all day and night. The reaction product was then ground in a coffee mill, and the entire amount was passed through 150 meshes. Galactomannan Hydrogen Comparative Example 1 The transparency of the guar gum used as a raw material in Example 1 was measured and found to be 25%.

Comparative Example 2 Using the same reaction vessel as in Example 1 and using the same method, galactomanna 2-)o ha/- was prepared according to the following recipe.
/l/ 150ml water
20ml guar gum powder
100g sodium hydroxide 6
g Water (for dissolving sodium hydroxide) 5Qml Propylene oxide 15g Example 2 In a pressurized autoclave with an internal volume of 6e, guagano with a moisture content of 12%, 600g of powder, and 2-prono (Nol 1200ml)
6 was prepared, stirred to form a suspension and dispersion, and a solution of 50 g of potassium hydroxide dissolved in 200 ml of water was gradually added. After purging the inside of the autoclave with nitrogen and stirring for 1 hour, 100 g of ethylene oxide was added and the mixture was heated at 55°C for 6 hours.
Allow time to react. After the reaction is completed, the inside of the autoclave is cooled to room temperature, replaced with nitrogen again, and the product is taken out. The reaction product was neutralized with a stoichiometric amount of glacial acetic acid, filtered, washed with 2000 ml of 80% 2-gropanol solution, filtered again and washed with 2000 ml of 2-propanol, and the product was filtered. Air dry. This is ground in a coffee mill to produce galactomannan. Applicant: Mitsubishi Acetate Co., Ltd. and one other representative, patent attorney Masao Kobayashi 19-

Claims (1)

[Claims] It is characterized in that galactomannan is reacted with alkylene oxide in the presence of 0.4 mol or more of alkali metal hydroxide per anhydrosaccharide unit of galactomannan, using a hydrophilic organic solvent and water as a medium. A method for producing hydroxyalkyl ether of galactomannan whose aqueous solution has excellent transparency.