Infra-red synthesis of crosslinked carboxymethyl fecula

Abstract

The present invention relates to an infrared synthetic method of a cross-linked carboxymethyl starch, comprising (1) adding the monochloroacetic acid into the container, neutralizing the monochloroacetic acid by the sodium hydroxide, cooling the solution, adding the ethanol solution, dripping the chloroepoxy propane, and then adding the primary starch; (2) stirring and pre-reacting the materials in the container, then pouring the mixture out from the container, centrifuging the mixture to remove a little liquid, and then breaking the filter cake; (3) putting the broken filter cake into the infrared reactor, auto reacting at a constant temperature to obtain the modified starch, putting the starch out to crush. The invention uses the technology of infrared catalyzing and etherifying as well as heating and drying at the same time to accelerate the reaction, improve the product property, increase the viscosity of the aqueous solution of carboxymethyl starch and broaden the range of use of the product. And at the same time, the invention reduces the consumption of the organic solvent, has no need to recycle the alcohol, reduces the energy consumption, shortens the reaction time, raises efficiency, and reduces the production cost of the cross-linked carboxymethyl starch.

Description

technical field [0001] The invention relates to starch modification technology, in particular to an infrared synthesis method of cross-linked carboxymethyl starch. technical background [0002] Starch can be modified single-time or compound-modified. Starch carboxymethylation and crosslinking are two types of modification methods developed earlier. Carboxymethylation refers to the etherification reaction between starch and monochloroacetic acid in the presence of sodium hydroxide, which is a bimolecular nucleophilic substitution reaction. The alcoholic hydroxyl group in the glucose unit is replaced by carboxymethyl. The reaction process is as follows: [0003] (1) Starch-OH+NaOH→Starch-O-Na+H 2 o [0004] (2) Starch-O-Na+ClCH 2 COONa→starch-O-CH 2 COONa+NaCl [0005] After carboxymethylation of starch, the starch has strong hydrophilicity, and the degree of substitution above 0.1 can be dissolved in water at low temperature, and a clear and transparent sticky starch pa...

AI Technical Summary

Problems solved by technology

The water-based method can only produce products with a degree of substitution of less than 0.07. This is because carboxymethyl starch with a higher degree of substitution is easy to gelatinize in cold water, and the product is difficult to purify and recover, and the amount of waste water is large, causing environmental pollution.

Adding organic solvents such as ethanol, propanol or isopropanol to the organic solvent method prevents the gelatinization of carboxymethyl starch in the reaction, and can prepare products with high substitution degree and high purity, which is a production method widely used in industry ; But the disadvantage is that more organic solvents are needed, the recovery is difficult and the recovery rate is low, and the product cost is high

The dry method does not use organic solvents, and the preparation time is short; but the equipment requirements are relatively high, it is difficult to control, and the reaction is uneven, and the product contains impurities such as residual reaction reagents.

The semi-dry method is between the organic solvent method and the dry method, saving cost, no pollution, uniform and easy to control the reaction, and the obtained product can still maintain the original starch granule structure, has good fluidity, is easy to dissolve in water and does not agglomerate; but the product still contains some impurities