STARCH DERIVATIVES AND ITS MANUFACTURING METHOD

Abstract: This invention relates to novel carboxymethyl-etherified starch derivatives and its manufacturing method and more particularly, to the novel carboxymethyl-etherified starch derivatives and its manufacturing method, wherein its viscosity in 5 % aqueous solution is 15 APPROX 600 cps, when measured by a viscometer in Hakke rotary type; permeability in 0.1 % aqueous solution shows more than 95 % in 625 nm, when measured by UV spectrophotometer; viscosity values at the maximum temperature of 95 DEG C and at the temperature cooled to 50 DEG C are 6 APPROX 304 BU and 6 APPROX 720 BU, respectively when measured by Brabender viscometer. According to this invention, the cool water-soluble carboxymethyl-etherified starch derivatives are prepared in the following steps: starches (such as corn, potato, wheat and rice) as main materials are dissolved in organic solvents such as lower alcohol without hydrolysis, or hydrolyzed in the presence of inorganic acids such as hydrochloric acid or sulfuric acid at 25 to 75 DEG C for 30 minutes to 72 hours. Then, with the addition of etherifing agent in the presence of alkali, some organic solvent of lower alcohol was further added to the mixture for reaction thereof. The reactant was neutralized, purified with organic solvents and dried to give the desired product.

Description: Starch derivatives and its manufacturing method FIELD OF THE INVENTION This invention relates to novel carboxymethyl- etherified starch derivatives and its manufacturing method and more particularly, to the novel carboxymethyl- etherified starch derivatives and its manufacturing method, wherein its viscosity in 5S> aqueous solution is 15-600 cps, when measured by a viscometer in Ha e rotary type , permeability in 0.1& aqueous solution shows more than 95% in 625 nm, when measured by UV spectrophotometer ; viscosity values at the maximum temperature of 95 C C and at the temperature cooled to 50 , are 6-304 Bϋ and 6-720 Bϋ, respectively when measured by Brabender viscometer. DESCRIPTION OF THE RELATED ART In general, etherified or esterified starch derivatives have been used as an enhancer and stabilizer for viscosity in the foods industry ; a carrier designed to manufacture dyestuff and dyeing agents in the crude dyeing industry. Further said derivatives are being widely used in other industries such as papers, pharmaceuticals, etc. The starch derivatives include methylated starch, ethylated starch, hydroxyethyl starch, hydroxypropyl starch, carboxymethyl starch, formic acid starch, acetic acid starch, hydroxypropylpropionic acid starch, and butylic acid starch. Said starch derivatives, showing a relatively high viscosity in 10 to 20% aqueous solution have a poor transparency and when exposed at room temperature, their weak resistance to microorganisms may give rise to the formation of mold. In addition, since there are a wide gap of viscosities between the maximum temperature of 95°C and cooled temperature of 50t, when measured by Brabender viscometer, said starch derivatives is a weak resistance to the aging when they are cooled after the increase of the temperature. In U.S. Pat. No. 4837314 a method of manufacturing hydroxypropyl starch with low viscosity of less than 15,000 cps (Brookfield viscometer, 20 rpm) at relatively high concentration (10% aqueous solution) has been disclosed. However, since highly inflammable propylene oxide have to be employed as an etherifing agent in the manufacturing process, special care should be exercised for the prevention of explosion in the actual production. In the Japanese Kokai Patent Nos. 91-146502 and 91-146503 which refer to the manufacture of carboxymethyl- etherified salts of starch having the average degree of substitution of more than 0.2 through the reaction of sweet potato or corn starch with alkali in the presence of aqueous solution of etherifing agent, another method of manufacturing carboxymethyl-etherified salts of sweet potato starch having the average degree of substitution of more than 0.2 has been also disclosed. According to said conventional method, more than 7 moles of water as reaction medium should be used to 1 mole of sweet potato starch. Even though the degree of substitution is good, larger facility should be established due to requirement of a lot of water in the manufacturing process and with more complicated re-processes involved in pulverizing, neutralizing and purifying the molding, the transparency proves to be poor. SUMMARY OF THE INVENTION To be free from the aforementioned shortcomings, the object of this invention is to provide cool water-soluble carboxymethyl-etherified starch derivatives, characterized in that ; said starch derivatives in 10 to 20% aqueous solution may have low viscosity, said starch derivatives in low concentration may have high viscosity, the transparency of said starch derivatives in 0.1% aqueous solution has more than 95%, when measured by UV spectrophotometer, said starch derivatives have a resistance to microorganisms, said starch derivatives, in heating and cooling, have a strong resistance to the aging. According to this invention, the cool water-soluble carboxymethyl-etherified starch derivatives are prepared in the following steps : Some starches (e.g., corn, potato, wheat and rice) as main materials are dissolved in organic solvents such as lower alcohol without hydrolysis, or hydrolyzed in the presence of inorganic acids such as hydrochloric acid or sulfuric acid at 25 to 75'C for 30 minutes to 72 hours. Then, with the addition of etherifing agent in the presence of alkali, some organic solvent such as lower alcohol was further added to the mixture for reaction thereof. The reactant was neutralized, purified with organic solvents and dried to give the cool water-soluble carboxymethyletherified starch derivatives. According to this invention, the lower alcohol presents lower alcohols of C1-3, includes methanol, ethanol or isopropyl alcohol while using caustic soda (NaOH) or KOH as alkali. The etherifing agent presents etherifing agents having one functional group, includes lower alkylhalides of C1-4, lower alkyldisulfates of C1-4, lower alkylene oxides, halogenated lower carboxylic acids and its salts. Further more specifically, said halides include methyl chloride or ethyl chloride, disulfates include dimethylsulfate or diethylsulfate, oxides include ethylene oxide or propylene oxide, carboxylic acid or its salts include monochloroacetic acid, bromoacetic acid or its alkali metal salts. Among them, monochloroacetic acid is the most preferable in embodying this invention. Hence, the reaction temperature for etherification is 20-75 * 0 and the reaction time is 30 minutes to 3 hours. For the etherification reaction, some alkali materials including alkali metal oxide or its hydroxide or ammonium hydroxide may be employed together with etherifing agent. Among them, caustic soda (sodium hydroxide) is preferably used for better etherification reaction and said reaction may be efficiently conducted in approx. 20-70% aqueous solution, preferably in 30—60% aqueous solution. In a water system containing less than 20% in alkali concentration, half amounts of added monochloroacetic acid is hydrolyzed and this may affect the yield thereto. In case of exceeding 70% in alkali concentration, starches are sparsingly soluble to water so that reaction cannot be conducted homogeneously. After etherification reaction is completed, the reactant during purification should not be made in the form of paste or gelatination and its desalting process is performed with common methods such as inclination, filtration and centrifuge. The cool water-soluble carboxymethyl-etherified starch derivatives manufactured in accordance with this invention are characterized in that;- In case of 0.1% aqueous solution of said derivatives measured by UV spectrophotometer in 625 nm, its permeability shows more than 95%, - In case of 5% aqueous solution of said derivatives measured by a viscometer in Hakke rotary type, its viscosity ranges 15-600 cps, and when measured by Brabender viscometer, the viscosity is 6-304 BU at the maximum temperature of 95 ° C and 6-720 BU at the cooled temperature, - In case of 5—20% aqueous solution of said derivatives, its long-term storage testing at room temperature (25 * C) for 6 months revealed the resistance against bacteria. Compared with the conventional carboxymethyl¬ etherified starch derivatives, therefore, it is well understood that the carboxymethyl-etherified starch derivatives of this invention is superior in terms of transparency, viscosity, bacteria-resistance and aging. This invention is explained in more detail by the following examples. EXAMPLE 1 500 g of potato starch was dissolved in 755 ml of methanol and with the addition of 248.2 g of monochloroacetic acid (CICH2COOH), the mixture was stirred for one hour. Then, a solution containing 312 g of caustic soda dissolved in 428.5 g of water was added to said mixture and stirred at 37 ° C for 50 minutes. The reactant was neutralized, purified with 85% methanol and dried to give a dried product (1). As shown in Fig. 1, the test results of 0.1% aqueous solution of said dried product(1), so prepared, revealed that transparency measured by UV spectophotometer was 96.5% in 625 nm. Further the test results of 5% aqueous solution were as follows : - Viscosity was 500 cps at the shear rate of 150 sec "1 , when measured by a viscometer in Hakke rotary type ; - Formation of bacteria was not detected from the long-term storage testing at room temperature (25 * C) for 6 months ; - Viscosities at the maximum temperature of 95 C C and at a temperature cooled to 50 ° C were 304 BU and 430 BU, respectively when measured by Brabender viscometer. The test conditions and their evaluation of Fig.1 are as follows : 1) Test conditions Moisture : 18.0 [%] Correction : 14.0 [%] Corr. to 14% : 20.0 [g] Sample weight : 20.0 [g] Corr. to 14% : 399.1 [ml] Water : 400.0 [ml] Speed 70 [r/min] Meas. range : 1000 [cmg] Start temp. : 30 [°C] Heat/cool rate : 1.5 [°C/min] Max. temp. : 95 [TJ] Up. hold time : 15 [min] End temp. 50 [IC] Fin. hold time : 15 [min] 2) Evaluation EXAMPLE 2 500 g of corn starch was hydrolyzed with 0.5N- hydrochloric acid at 25"C for 30 minutes and with the addition of 205 g of monochloroacetic acid and 1180 ml of methanol as solvent, the mixture was stirred for one hour. Then, a solution of caustic soda containing 189 ml of caustic soda dissolved in 400 ml of water was added to said mixture and stirred at 50°C for 2.5 hours. The reactant was neutralized, purified with 90% methanol and dried to give a dried product (2). 0.1% aqueous solution of said dried product (2) was prepared and its transparency measured based upon the same method as described in Example 1 was 95.1% in 625 nm. Further the test results of 5% aqueous solution which was left for 6 months revealed that there was no formation of bacteria. EXAMPLE 3 500 g of potato starch was hydrolyzed with 4N- hydrochloric acid at 50 ° C for 45 minutes and with the addition of 250 g of monochloroacetic acid and 1328 ml of ethanol as solvent, the mixture was stirred for one hour and twenty minutes. Then, 245 g of caustic soda was added to said mixture and stirred at room temperature for 3 hours. The reactant was neutralized, purified with 75% methanol and dried to give a dried product (3). 0.1% aqueous solution of said dried product (3) was prepared and its transparency measured based upon the same method as described in Example 1 was 95.6% in 625 nm. Further the test results of 5% aqueous solution which was left for 6 months revealed that there was no formation of bacteria. EXAMPLE 4 500 g of potato starch was hydrolyzed with 3N- hydrochloric acid at 25T: for 30 minutes and with the addition of 248 g of monochloroacetic acid and 1250 ml of ethanol as solvent, the mixture was stirred for 1.5 hours. Then, a solution of caustic soda containing 275 g of caustic soda dissolved in 612 ml of water was added to said mixture and stirred at 60°C for 2 hours. The reactant was neutralized, purified with 90% methanol and dried to give a dried product (4). As shown in Fig. 2, the test results of 0.1% aqueous solution of said dried product(4), so prepared, revealed that transparency based upon the same method as described in Example 1 was 98.2%. Further the test results of 5% aqueous solution were as follows : - Viscosity was 500 cps at the shear rate of 150 sec "1 , when measured by a viscometer in Hakke rotary type ; - Formation of bacteria was not detected from the long-term storage testing at room temperature (25"O for 6 months ; - Viscosity values at 30°C, 95°C and at a temperature cooled again to 50"C were 562 BU, 207.0 BU and 254 BU, respectively when measured by Brabender viscometer. The test conditions and their evaluation of Fig.2 are as follows: 1) Test conditions Moisture : 18.0 [%] Correction : 14.0 [%] Corr. to 14% : 15.7 [g] Sample weight : 15.0 [g] Corr. to 14% : 299.2 [ml] Water 300.0 [ml] Speed : 70 [r/min] Meas. range : 1000 [cmg] Start temp. : 30 [TJ] Heat/cool rate : 1.5 [T /min] Max. temp. 95 TC] Up. hold time : 15 [min] End temp. 50 [TJ] Fin. hold time : 15 [min] 2) Evaluation EXAMPLE 5 500 g of potato starch was hydrolyzed with 5N- hydrochloric acid at room temperature for 72 hours and with the addition of 248 g of monochloroacetic acid and 1280 ml of ethanol as solvent, the mixture was stirred for 1 hour. Then, 200 g of caustic soda was added to said mixture and stirred at 45°C for 2 hours. The reactant was neutralized, purified with 80% methanol and dried to give a dried product (5). As shown in Fig. 3, the test results of 0.1% aqueous solution of said dried product (5), so prepared, revealed that transparency based upon the same method as described in Example 1 was 96.9%. Further the test results of 5% aqueous solution were as follows : - Formation of bacteria was not detected from the long-term storage testing for 6 months ; - Viscosity values at 30TJ, 95TJ and 50Tj were 23 BU, 7 BU and 6 BU, respectively when measured by Brabender viscometer. The test conditions and their evaluation of Fig.3 are as follows: 1) Test conditions Moisture : 18.0 [%] Correction : 14.0 [%] Corr. to 14% : 15.7 [g] Sample weight : 15.0 [g] Corr. to 14% 299.2 [ml] Water 300.0 [ml] Speed 70 [r/min] Meas. range : 1000 [cmg] Start temp. 30 [Tj] Heat/cool rate : 1.5 [TJ/min] Max. temp. 95 [TJ] Up. hold time : 10 [min] End temp. 50 [TJ] Fin. hold time : 20 [min] 2) Evaluation EXAMPLE 6 500 g of potato starch was hydrolyzed with 2.8N- hydrochloric acid at 40TJ for 40 minutes and with the addition of 355 g of monochloroacetic acid and 2500 ml of ethanol as solvent, the mixture was stirred for one hour and 25 minutes. Then, a solution of caustic soda containing 295 g of caustic soda dissolved in 613 ml of water was added to said mixture and stirred at 70'C for 2 hours. The reactant was neutralized, purified with 90% methanol and S dried to give a dried product (6). As shown in table 4, the test results of 0.1% aqueous solution of said dried product (6), so prepared, revealed that transparency based upon the same method as described 0 in Example 1 was 96.S%. Further the test results of 20% aqueous solution were as follows : - Formation of bacteria was not detected from the long-term storage testing for 6 months ; - Viscosity values at 30TJ, 95TJ and 50TJ were 18 BU, 8 BU and 6 BU, respectively when measured by Brabender viscometer. The difference of viscosity from 95TJ to 50TJ is 2 BU. The test conditions and their evaluation of Fig.4 are as follows: 1) Test conditions Moisture : 18.0 [%] Correction : 14.0 [%] Corr. to 14% : 15.7 [g] Sample weight : 15.0 [g] Corr. to 14% : 299.2 [ml] Water : 300.0 [ml] Speed : 70 [r/min] Meas. range : 1000 [cmg] Start temp. : 30 [TJ] Heat/cool rate : 1.5 [TJ/min] Max. temp. : 95 [TJ] Up. hold time : 15 [min] End temp. 50 [T ] Fin. hold time : 15 [min] 2) Evaluation COMPARATIVE EXAMPLE 1 As shown in Fig. 5, the viscosity values of Pullulan (Hayashibara, Japan) containing non-carboxymethyl starch derivatives, which was purchased from the local market, were measured by Brabender viscometer ; 10 BU at the initial temperature of 30TJ, 78 Bϋ at 95TJ and 6 BU at 80TJ. The test conditions and their evaluation of Fig.5 are s as follows: 1) Test conditions Moisture : 18.0 [%] Correction 14.0 [%] Corr. to 14% : 20.9 [g] Sample weight : 20.0 [g] ] J> Corr. to 14% : 399.1 [ml] Water : 400.0 [ml] Speed : 70 [r/min] Meas. range : 1000 [cmg] Start temp. : 30 [Tj] Heat/cool rate : 1.5 [Tj/min] Max. temp. 95 [T ] Up. hold time : 15 [min] 15 End temp. 50 [T ] Fin. hold time : 15 [min] 2)Evaluation 0 COMPARATIVE EXAMPLE 2 As shown in Fig. 6, the viscosity values of potato starch raw materials, which were purchased from the local market, were measured by Brabender viscometer; 243 BU at 95°C and 419 BU at 80TJ. The test conditions and their evaluation of Fig.6 are as follows: 1) Test conditions Moisture : 18.0 [%] Correction 14.0 [%] Corr. to 14% : 20.9 [g] Sample weight : 20.0 [g] Corr. to 14% : 399.1 [ml] Water : 400.0 [ml] Speed : 70 [r/min] Meas. range : 1000 [cmg] Start temp. : 30 [T ] Heat/cool rate : 1.5 [Tj/min] Max. temp. 95 [TJ] Up. hold time : 15 [min] End temp. 50 [TJ] Fin. hold time : 15 [min] 2) Evaluation For reference Fig.7 is a viscograph showing the test results on Examples 1, 4, 5, 6 of this invention and Pullulan of comparative example 1 in 5% aqueous solution, which measured by a viscometer in Hakke rotary type. From the aforementioned tests, it is well understood that the cool water-soluble carboxymethyl-etherified starch derivatives manufactured in accordance with this invention are characterized in that ; - In case of 0.1% aqueous solution of said derivatives measured by UV spectrophotometer in 625 nm, its permeability shows more than 95%, - In case of 5% aqueous solution of said derivatives measured by a viscometer in Hakke rotary type, its viscosity ranges 15-600 cps, and when measured by Brabender viscometer, the viscosity is 6-304 BU at the maximum temperature of 95TJ and 6-720 BU at the cooled temperature of 50TJ, - In case of 5-20% aqueous solution of said derivatives, its long-term storage testing at room temperature (25TJ) for 6 months revealed the resistance against bacteria. Now that the carboxymethyl-etherified starch derivatives of this invention in relatively high concentration of 10-20% aqueous solution may be freely controlled in any level of viscosity, that is, from the high concentration and low viscosity to the low concentration and high viscosity. Various kinds of starch derivatives of the invention having the extended solubilities of 1%, 5%, 10%, 20% and 30% and having a property of from the relatively low concentration and high viscosity to the high concentration and low viscosity, may be widely applied in the industrial fields involved. BREIF DESCRIPTION OF THE DRAWINGS Fig. 1 is a viscograph in which starch derivatives, manufactured according to Example 1 of this invention, are measured by Brabender viscometer, Fig. 2 is a viscograph in which starch derivatives, manufactured according to Example 4 of this invention, are measured by Brabender viscometer, Fig. 3 is a viscograph in which starch derivatives, manufactured according to Example 5 of this invention, are measured by Brabender viscometer, Fig. 4 is a viscograph in which starch derivatives, manufactured according to Example 6 of this invention, are measured by Brabender viscometer, Fig.5 is a viscograph in which Pullulan, a well-known substance, is measured by Brabender viscometer, Fig. 6 is a viscograph in which potato starch is measured by Brabender viscometer, Fig. 7 is a viscograph showing the test results on Examples 1, 4, 5, 6 of this invention and Pullulan of comparative example 1 in 5% aqueous solution, when measured by a viscometer in Hakke rotary type

Claims: WHAT IS CLAIMED IS : 1. Cool water-soluble carboxymethyl-etherified starch derivatives characterized in that ; 1) The viscosity of 5% aqueous solution is 15-600 cps, when measured by a viscometer in Hakke rotary type, 2) The transparency of 0.1% aqueous solution shows more than 95% of permeability, when measured by UV spectrophotometer in 625 nm, 3) The viscosity values at 95Tj and at the temperature cooled to 50TJ are 6-304 BU and 6-720 BU, respectively when measured by Brabender viscometer. 2. Process for manufacturing cool water-soluble carboxymethyl starch derivatives having the charateristics of claim 1 wherein starches such as corn, potato, wheat and rice are dissolved in organic solvents such as lower alcohol without hydrolysis, or hydrolyzed in the presence of inorganic acids, then with the addition of etherifing agent in the presence of alkali, some organic solvent of lower alcohol was further added to the mixture for reaction thereof and after the reactant was neutralized, purified with organic solvents and dried. 3. Process according to claim 2 for using lower alcohols of Cι-3 such as methanol, ethanol or isopropyl alcohol as organic solvent of lower alcohol. 4. Process according to claim 2 for hydrolyzing starches in the presence of hydrochloric acid or sulfuric acid at 25-70TJ for 30 minutes to 72 hours. 5. Process according to claim 2 for reacting starches in alkali concentration of 20-70% at 25-70TJ for 30 minutes to 3 hours by using caustic soda (NaOH) or OH as alkali, and monochloroacetic acid as etherifing agent. 6. Process according to claim 2 for using alcohol aqueous solution of more than 60% as organic solvent for purification.

Inventors: CHO YANG RAE, KO CHUL JONG, KWON SANG GI, PARK CHAN HUN, CHO, YANG, RAE, KO, CHUL, JONG, KWON, SANG, GI, PARK, CHAN, HUN
Applicants: CHO YANG RAE, KO CHUL JONG, KWON SANG GI, PARK CHAN HUN, TAE KYUNG CO LTD, CHO, YANG, RAE, KO, CHUL, JONG, KWON, SANG, GI, PARK, CHAN, HUN, TAE KYUNG CO., LTD.
Application year: 1997
Main classification: C08B31
IPC codes: C08B31