Method for preparing sodium carboxymethylstarch

Abstract

The invention discloses a preparation method of sodium carboxymethyl starch with hyperviscosity, which uses the pre-mixture of urea and aldehyde, to process etherification between starch and chloroacetic acid, to obtain sodium carboxymethyl starch at 72000mPa. s (2%, 25DEG C) viscosity. The inventive sodium carboxymethyl starch has high viscosity, wide application, simple preparation, low cost, and industrialization production support.

Description

technical field

[0001] The invention relates to the technical field of starch modification, in particular to a method for preparing ultrahigh-viscosity sodium carboxymethyl starch. Background technique

[0002] Sodium carboxymethyl starch is an anionic polymer electrolyte with excellent wettability, dispersibility, cohesiveness, thickening, emulsification and dispersibility, water retention, surface activity, film-forming and compatibility, widely It is used in technical fields such as food, medicine, textile printing and dyeing, papermaking, petroleum, paint, ceramics, daily chemicals, adhesives, mineral processing, and agricultural production. The preparation of sodium carboxymethyl starch is usually obtained by etherification reaction of starch and chloroacetic acid or its sodium salt under alkaline conditions. According to the difference of the solvent system used, it is divided into four different processes: water solvent method, organic solvent...

Examples

Embodiment 1

[0016] Add 100 kg of cornstarch into a mixed solution of 210 kg of ethanol and water (78:22 in volume ratio) under stirring to form a uniform starch emulsion, then add 5 kg of urea and formaldehyde mixture (0.1:3 in mass ratio) ) and 20 kg of monochloroacetic acid were added into the reaction kettle, and after stirring evenly, the starch was activated for 15 minutes at a temperature of 38±1°C.

[0017] At the same time, 20 kg of NaOH solution with a mass concentration of 31% was slowly added dropwise to maintain the pH value of the system at 10.5. Then continue to react at 48° C. for 5 hours to end the reaction to obtain sodium carboxymethyl starch. The viscosity of its 2% aqueous solution measured at 25°C is 2700mPa.s.

Embodiment 2

[0019] Under stirring, add 100 kg of cornstarch into a mixed solution of 210 kg of ethanol and water (78:22 in volume ratio) to form a uniform starch emulsion, using 13 kg of a mixture of urea and formaldehyde (mass ratio of 3:0.1) , 25 kilograms of monochloroacetic acid, activating starch for 50 minutes at a temperature of 40 ± 1° C., maintaining the pH value of the system at 10.5 with 31% sodium hydroxide and potassium carbonate, and reacting at a constant temperature of 52° C. for 5 hours. Other reaction conditions are the same as the examples 1. The 2% aqueous solution viscosity of the obtained sodium carboxymethyl starch is 5700mPa.s (25 ℃).

Embodiment 3

[0021] Using 160 kg of starch, 300 kg of ethanol and water mixture (85:15 in volume ratio), 22 kg of urea and formaldehyde mixture (1.4:1 in mass ratio), 25 kg of monochloroacetic acid, at a temperature of 48±1°C The starch was activated for 40 minutes. The pH value remained at 11, and at 50° C. for constant temperature reaction for 5 hours, other reaction conditions were with embodiment 1, and the 2% solution viscosity of the obtained sodium carboxymethyl starch was 25000mPa.s (25° C.).

technical field

[0001] The invention relates to the technical field of starch modification, in particular to a method for preparing ultrahigh-viscosity sodium carboxymethyl starch. Background technique

[0002] Sodium carboxymethyl starch is an anionic polymer electrolyte with excellent wettability, dispersibility, cohesiveness, thickening, emulsification and dispersibility, water retention, surface activity, film-forming and compatibility, widely It is used in technical fields such as food, medicine, textile printing and dyeing, papermaking, petroleum, paint, ceramics, daily chemicals, adhesives, mineral processing, and agricultural production. The preparation of sodium carboxymethyl starch is usually obtained by etherification reaction of starch and chloroacetic acid or its sodium salt under alkaline conditions. According to the difference of the solvent system used, it is divided into four different processes: water solvent method, organic solvent...

Examples

Embodiment 1

[0016] Add 100 kg of cornstarch into a mixed solution of 210 kg of ethanol and water (78:22 in volume ratio) under stirring to form a uniform starch emulsion, then add 5 kg of urea and formaldehyde mixture (0.1:3 in mass ratio) ) and 20 kg of monochloroacetic acid were added into the reaction kettle, and after stirring evenly, the starch was activated for 15 minutes at a temperature of 38±1°C.

[0017] At the same time, 20 kg of NaOH solution with a mass concentration of 31% was slowly added dropwise to maintain the pH value of the system at 10.5. Then continue to react at 48° C. for 5 hours to end the reaction to obtain sodium carboxymethyl starch. The viscosity of its 2% aqueous solution measured at 25°C is 2700mPa.s.

Embodiment 2

[0019] Under stirring, add 100 kg of cornstarch into a mixed solution of 210 kg of ethanol and water (78:22 in volume ratio) to form a uniform starch emulsion, using 13 kg of a mixture of urea and formaldehyde (mass ratio of 3:0.1) , 25 kilograms of monochloroacetic acid, activating starch for 50 minutes at a temperature of 40 ± 1° C., maintaining the pH value of the system at 10.5 with 31% sodium hydroxide and potassium carbonate, and reacting at a constant temperature of 52° C. for 5 hours. Other reaction conditions are the same as the examples 1. The 2% aqueous solution viscosity of the obtained sodium carboxymethyl starch is 5700mPa.s (25 ℃).

Embodiment 3

[0021] Using 160 kg of starch, 300 kg of ethanol and water mixture (85:15 in volume ratio), 22 kg of urea and formaldehyde mixture (1.4:1 in mass ratio), 25 kg of monochloroacetic acid, at a temperature of 48±1°C The starch was activated for 40 minutes. The pH value remained at 11, and at 50° C. for constant temperature reaction for 5 hours, other reaction conditions were with embodiment 1, and the 2% solution viscosity of the obtained sodium carboxymethyl starch was 25000mPa.s (25° C.).