JPH052682B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a carboxymethyl ether alkali metal salt of tamarind seed gum. Tamarind seed gum is a polysaccharide mainly consisting of glucose xylos and galactose obtained by separating and refining the seeds of Tamarindus indica Linn, an evergreen leguminous tree that grows in the tropics.The amount varies depending on the degree of purification, but there are no impurities. It contains 2 to 40% protein and fat, and is a white or light brown powder. Also, usually water is 5 to 13
Contains %. This tamarind seed gum forms a viscous aqueous solution, is relatively stable against acids, salts and heat, and also forms a strong jelly, making it useful in tonkatsu sauce, soy sauce thickening stabilizer, ice cream, etc. It is widely used in the food field as a stabilizer for shearbet, etc., and a gelling agent for jams, marmalades, etc. Moreover, it does not dissolve in cold water and requires heating to about 75°C or higher to obtain an aqueous solution, so it is not used much in industrial applications such as printing pastes outside of the food field. In order to improve the solubility of this tamarind seed gum in cold water, attempts have been made to hydroxyethylate it with the addition of ethylene oxide and to hydroxypropylate it with the addition of propylene oxide. These derivatives, like tamarind seed gum, are nonionic derivatives, but they are made into anionic derivatives by reacting with monochloroacetic acid or its salt, not only for the purpose of cold water solubilization but also for the addition of new functions. Prototypes of carboxymethyl ether alkali metal salts of tamarind seed gum have also been made. Conventional carboxymethyl ether alkali metal salts of tamarind seed gum are produced by a method in which tamarind seed gum is reacted with sodium hydroxide and monochloroacetic acid or its salt using water as a solvent (Italian Patent No. 574928), and methyl alcohol. It is produced by a method in which a reaction is carried out using an aqueous solution as a medium (US Pat. No. 4,089,647). However, the method of carrying out the carboxymethylation reaction of tamarind seed gum using water as a solvent is not suitable for industrial use because tamarind seed gum swells significantly with an aqueous sodium hydroxide solution and becomes extremely viscous dope-like, making stirring and mixing difficult. This poses a major obstacle in the process. In addition, sodium monochloroacetate, which is an etherification agent, reacts with sodium hydroxide rather than with tamarind seed gum in water to produce sodium glycolate, which is a dominant side reaction. The disadvantage is that the effective utilization rate is extremely low and the cost is high. Furthermore, it is expected to be extremely difficult both technically and economically to recover the carboxymethyl ether alkali metal salt of tamarind seed gum, which is the product, from the viscous dope after the completion of the reaction. Therefore, the carboxymethyl ether alkali metal salt of tamarind seed gum using water as a solvent,
In particular, it is extremely difficult to industrially produce compounds with an average degree of substitution (hereinafter abbreviated as DS) of 0.4 or higher. In addition, the manufacturing method using an aqueous methyl alcohol solution as a solvent suppresses the swelling of tamarind seed gum due to an aqueous sodium hydroxide solution, but sodium glycolate due to a side reaction between the etherifying agent, sodium monochloroacetate and sodium hydroxide. Since the production is accelerated rather than in the case where water is used as a solvent, the effective utilization rate of the etherifying agent is extremely low, which is economically disadvantageous in industrialization. The side reaction promotion phenomenon of sodium monochloroacetate when using this aqueous methyl alcohol solution as a solvent is due to the fact that the equilibrium point of the equilibrium reaction for producing the alcoholate of the following formula in an aqueous alcohol solution containing sodium hydroxide is the iso of the present invention. - CH ₃ OH + NaOHCH ₃ ONa + H ₂ O is shifted to the right to a greater extent than in the case of other alcohols such as propyl alcohol, which suppresses the adsorption of sodium hydroxide onto tamarind seed gum and etherifies the sodium methylate produced. This is thought to be due to the promotion of side reactions of the agent, sodium monochloroacetate. As described above, all conventional methods for producing carboxymethyl ether alkali metal salts of tamarind seed gum have many drawbacks.
Industrialization is very difficult. As a result of intensive research into an industrially viable method for preparing the carboxymethyl ether alkali metal salt of tamarind seed gum, the present inventors discovered that tamarind seed gum was dispersed in an aqueous solution of a hydrophilic organic solvent, and an alkali and etherification agent were used. When producing the carboxymethyl ether alkali metal salt of tamarind gum, one of n-propyl alcohol, iso-propyl alcohol, tert-butyl alcohol, and acetone is used as a hydrophilic organic solvent. By adopting a manufacturing method characterized by using ~95% aqueous solution 1 to 20 times the weight of tamarind seed gum, swelling of tamarind seed gum is suppressed and an extremely high effective utilization rate of the etherifying agent is achieved. , the average degree of substitution
It has been found that carboxymethyl ether alkali metal salts of tamarind seed gum of 0.2 to 2.5 can be prepared. The reason why the method of the present invention suppresses the swelling of tamarind seed gum due to alkali and achieves an extremely high effective utilization rate of the etherifying agent is as follows.
When an alkali is added to the aqueous solution of the hydrophilic organic solvent used in the present invention, it separates into two phases: a concentrated alkaline aqueous solution phase and a water-containing organic solvent phase. Forms a tamarind seed gum phase.
On the other hand, the water-containing organic solvent phase surrounds the alkaline tamarind seed gum phase to prevent agglomeration of the alkaline tamarind seed gum and facilitate stirring and mixing. It is thought that by using such a mechanism, significant swelling and agglomeration caused by alkali can be prevented by using a water-containing organic solvent using the minimum amount of alkali and water necessary for the reaction. In addition, among the alkali salts of morochloroacetic acid, which are etherification agents, those suspended or dissolved in the water-containing organic solvent phase have almost no alkali present in this system, so side reactions with alkalis hardly occur. do not have. On the other hand, those dissolved in the alkali tamarind seed gum phase mainly react with the alkali tamarind seed gum to become carboxymethyl-teral alkali metal salts. Therefore, the effective utilization rate of the etherification agent is considered to be extremely high. Note that hydrophilic organic solvents other than those of the present invention are not preferred for the following reasons. For example, an aqueous ethyl alcohol solution does not separate into a concentrated alkaline phase and a water-containing ethyl alcohol phase when used in a normal amount of alkali, and, like an aqueous methyl alcohol solution, tends to produce alcoholate, so the etherification agent can be used effectively. The ratio is significantly lower than when using the hydrophilic organic solvent agent of the present invention. Furthermore, n-butyl alcohol, sec-butyl alcohol, iso-amyl alcohol, methyl ethyl ketone, etc. are not preferred because they have low compatibility with water. In addition, polyhydric alcohols such as ethylene glycol, propylene glycol, and glycerin are too hydrophilic, so the amount of alkali adsorbed to tamarind seed gum is small, and when an aqueous alkali solution is used, tamarind seed gum swells considerably. This is not desirable because it is recognized by 60% for the concentration of the hydrophilic organic solvent of the present invention
If the amount is below, the tamarind seed gum and the produced carboxymethyl ether alkali metal salt will swell or partially dissolve, making it difficult to stir and mix smoothly, and furthermore, the effective utilization rate of the etherification agent will be significantly lowered. On the other hand, if it exceeds 95%, the amount of water in the alkali tamarind seed gum phase becomes too small, which not only reduces the reaction efficiency of the etherifying agent, but also reduces the amount of water in the carboxymethyl ether alkali metal salt of the produced tamarind seed gum. Its solubility is also significantly low. The reaction can be carried out smoothly by using the organic solvent aqueous solution in an amount of 1 to 20 times, preferably 2 to 15 times the weight of the tamarind seed gum. In other words, if it is less than 1 times by weight, it is difficult to stir and mix uniformly, and if it is more than 20 times by weight, the amount of water in the reaction solvent will be too large, causing the raw material tamarind seed gum and the produced carboxymethyl ether alkali metal salt to swell. Not only does stirring and mixing become difficult, but the reaction efficiency of the etherifying agent also tends to be considerably low. The alkali used in the present invention may be sodium hydroxide, potassium hydroxide, etc., but sodium hydroxide is preferred because it is inexpensive. Further, as the etherifying agent, monochloroacetic acid and its sodium salt, or methyl, ethyl, isopropyl ester of monochloroacetic acid, etc. can also be used. The reaction apparatus used in the present invention can be either a cylindrical reaction tank equipped with a propeller-like stirring blade or a twin-screw Werner-type kneader, but is not limited to these specific reaction apparatuses. . By the production method of the present invention, a carboxymethyl ether alkali metal salt of tamarind seed gum with a DS of 0.2 to 2.5 can be produced. If the DS is less than 0.20, it is difficult to obtain a material with good solubility in cold water. On the other hand, considering the constituent polysaccharide of tamarind seed gum, it is difficult to produce one with a DS of more than about 2.5. Although the production method of the present invention has been described above, when compared with the production method of the carboxymethyl ether alkali metal salt of cellulose, which is the same natural polysaccharide and is industrially produced in large quantities, tamarind seed gum The difference is that depending on the conditions, the raw materials and products may swell significantly and become aggregated, making stirring and mixing impossible. The present invention was achieved by the inventors of the present invention, who, as a result of intensive studies, have discovered a method for producing carboxymethyl ether alkali metal salt of tamarind seed gum that prevents its agglomeration and has an extremely high effective utilization rate of the etherifying agent. It is. In addition, since the carboxymethyl ether alkali metal salt of tamarind seed gum produced by the method of the present invention is easily dissolved in cold water, it can be used as a printing paste, a fiber sizing agent, and a paper manufacturing agent, which have not been used until now. Demand for applications such as surface coating agents and latex emulsifiers is expected to increase, and it has great industrial utility. Examples and comparisons specifically explaining the present invention are shown below, but the present invention is not limited to the examples shown below. Furthermore, in Examples and Comparative Examples, parts refer to parts by weight, and % refers to % by weight. The effective utilization rate of monochloroacetic acid or its salt as an etherification agent, the average degree of substitution (DS) of the carboxymethyl ether alkali metal salt of the produced tamarind seed gum, and the measurement and calculation methods for the viscosity and transparency of a 1% aqueous solution are as follows: It is as follows. (1) Effective utilization rate of etherification agent Calculated using the following formula. Effective utilization rate of etherification agent = Average degree of substitution of carboxymethyl ether alkali metal salt in produced tamarind seed gum/Polysaccharide constituent unit 1
Number of moles of etherification agent per unit (2) Average degree of substitution (DS) Accurately weigh 1 g of carboxymethyl ether alkali metal salt of purified tamarind seed gum,
Put it in a platinum crucible or magnetic crucible and incinerate it at 600℃, titrate the sodium oxide produced by the ashing with N/10 sulfuric acid using phenolphthalein as an indicator, and calculate the titration amount Aml by entering the following formula. , asked for DS. Average degree of substitution (DS) = 152 x A x f / 10000 - 80 x A x f f: W / 10 Sulfuric acid titer Note that this DS indicates the composition ratio of tamarind seed gum polysaccharide as D-galactose:D-xylose. Assuming that :D-glucose=1:2:3,
It is calculated as the average degree of substitution by carboxymethyl group per polysaccharide structural unit by taking a weighted average of each component and assuming the average molecular weight of the polysaccharide structural unit as 152. (3) Viscosity 2.5 g of carboxymethyl ether alkali metal salt of tamarind seed gum was added to 1% pure water in a cylindrical glass container with a diameter of 55 mm and a depth of 125 mm.
After dissolving it in a concentrated solution and adjusting the temperature to 25°C, the viscosity was determined by reading the value after rotating the rotor at 60 rpm for 1 minute using a BL viscometer and multiplying it by a predetermined constant. . The unit is cps (centipoise). (4) Transparency The transparency of a 1% by weight aqueous solution of carboxymethyl ether alkali metal salt of tamarind seed gum under a certain light source is expressed by the height of the liquid column, and the higher the value, the better. Example 1 Into a separable flask equipped with a stirrer and a reflux condenser, 249.1 parts of iso-propyl alcohol and 70.7 parts of sodium hydroxide were dissolved in 61 parts of pure water, and the mixture was stirred, mixed, and cooled to adjust the temperature to 20°C. After that, 100 parts of tamarind seed gum (moisture 7%, purity 93%)
and stir and mix at 20℃ for 60 minutes. Next, 78.9 parts of monochloroacetic acid was dissolved in 78.9 parts of iso-propyl alcohol and charged, and the mixture was heated at 20 to 30℃ for 30 minutes.
Stir to mix for a minute. Next, raise the temperature to 70℃ in a hot water bath.
Perform the etherification reaction for 90 minutes. After the reaction is complete, excess sodium hydroxide is neutralized with acetic acid. After cooling, the reaction solvent was separated. Next, purify with 3000 parts of 75% methyl alcohol aqueous solution twice at room temperature for 30 minutes, and then
After replacing with 2000 parts of % methyl alcohol aqueous solution, the mixture was separated and dried in a steam dryer at 80° C. for 4 hours to obtain 140 parts of carboxymethyl ether sodium salt of tamarind seed gum. Table 1 shows the effective utilization rate of the etherification agent and the properties of carboxymethyl ether sodium salt in the produced tamarind seed gum. Examples 2, 3 and 4 Instead of iso-propyl alcohol in Example 1,
Examples 2 and 3 were carried out using n-propyl alcohol or ter-butyl alcohol, but under the same conditions as in Example 1. Example 4 was carried out under the same conditions as Example 1, except that acetone was used instead of alcohol and the etherification reaction was carried out at 58°C for 200 minutes.The reaction results are shown in Table 1. Comparative Example 1 249.1 parts of pure water and 70.7 parts of sodium hydroxide were placed in a separable flask equipped with a stirring device and a reflux condenser.
Dissolve part in water, stir, mix and cool to 20℃.
After that, add 100 parts of tamarind seed gum (moisture 7
%, purity 93%) and started stirring and mixing at 20°C. However, the tamarind seed gum significantly swelled and became sticky, making it impossible to stir, so the reaction was stopped. Comparative Example 2 The same conditions as in Example 1 were carried out, except that methyl alcohol was used in place of the iso-propyl alcohol in Example 1, and the etherification reaction was carried out at 67° C. for 120 minutes. The reaction results are shown in Table 1.

[Table] As is clear from Table 1, in Examples 1, 2, 3, and 4, in which the reaction was carried out using the production method of the present invention, there was no problem with stirring and mixing during the reaction, and the reaction efficiency of the etherifying agent was is much higher than that of Comparative Example 2, and the DS of the carboxymethyl ether sodium salt of the produced tamarind seed gum is also very high. Furthermore, it can be seen that the solubility and transparency of cold water are extremely excellent. Example 5 311.3 parts of iso-propyl alcohol and 18.5 parts of sodium hydroxide were dissolved in 61 parts of pure water and charged into a separable flask equipped with a stirring device and a reflux condenser, and the mixture was stirred, mixed, and cooled to 20°C. After stirring and mixing for 60 minutes, 100 parts of tamarind seed gum (moisture 7%, purity 93%) was added and mixed at 20°C for 60 minutes. Next, 16.7 parts of monochloroacetic acid was dissolved in 16.7 parts of iso-propyl alcohol.
Stir and mix for 30 minutes at 25°C. Next, the temperature was raised to 70°C in a hot water bath, and the etherification reaction was carried out for 90 minutes. Next, excess sodium hydroxide was neutralized with acetic acid and separated. Thereafter, washing and drying were performed in the same manner as in Example 1 to obtain 98 parts of carboxymethyl ether sodium salt of tamarind seed gum. Stirring and mixing during this reaction was carried out smoothly. Moreover, the effective utilization rate of the etherification agent was 85%. The DS of the product is 0.25, the viscosity is 160 cps,
The solubility in cold water was such that some insoluble matter was observed, and the transparency was 250. Example 6 1760.3 parts of io-propyl alcohol was charged into a No. 5 Werner type kneader with two-shaft stirring blades, and 254.7 parts of sodium hydroxide was added to 146.4 parts of pure water.
Dissolve and prepare. After cooling to 20-30°C, 200 parts of tamarind seed gum (moisture 7%, purity 97%) was charged and mixed with stirring at 20-30°C for 60 minutes. Next, 447.7 parts of monochloric acid was dissolved in 447.7 parts of iso-propyl alcohol, and added while cooling.
Stir and mix at 30°C for 30 minutes. Thereafter, the temperature was raised to 60°C for about 10 minutes, and the etherification reaction was carried out for 60 minutes. Next, 63.7 parts of sodium hydroxide dissolved in 42.5 parts of pure water is added, followed by an etherification reaction at 60° C. for 60 minutes. After that, 63.7 parts of sodium hydroxide was dissolved in 42.5 parts of pure water and added,
After stirring and mixing at ℃ for 15 minutes, the temperature was increased to 70℃ and 90
Perform the etherification reaction for minutes. Next, the slight remaining sodium hydroxide is neutralized with acetic acid. Thereafter, washing and drying were carried out in the same manner as in Example 1 to obtain 382 parts of carboxymethyl ether sodium salt of tamarind seed gum of the present invention. Stirring and mixing during this reaction was carried out smoothly. Moreover, the effective utilization rate of the etherification agent was 54.6%. The DS of the product is 2.15, the viscosity is 86 cps, the solubility in cold water is excellent, and the clarity is
It was 750〓. As is clear from Examples 5 and 6, by the production method of the present invention, the carboxymethyl ether alkali metal salt of cold water soluble tamarind seed gum with a DS of 0.20 to 2.2 was produced with extremely high reaction efficiency (etherification agent effectiveness). (utilization rate) and can be easily manufactured. In addition, high DS products with DS of 2.2 to 2.5 can be manufactured by repeating the method of Example 1 or Example 6 once or twice using the product obtained in Example 6 as a raw material. I can do it.

Claims (1)

[Claims] 1. When producing a carboxymethyl ether alkali metal salt of tamarind seed gum by acting on an alkali and an etherifying agent with tamarind seed gum dispersed in an aqueous solution of a hydrophilic organic solvent, n- A tamarind seed gum characterized in that a 60 to 95% aqueous solution of an organic solvent of any one of propyl alcohol, iso-propyl alcohol, tert-butyl alcohol and acetone is used in an amount of 1 to 20 times the weight of tamarind seed gum. Method for producing carboxymethyl ether alkali metal salt.