Method for preparing composite modified starch

Abstract

The invention discloses a method for preparing composite modified starch. The method comprises the following steps: 1) slurrying a raw material, namely a natural starch, and adjusting pH value of the natural starch by caustic alkali; 2) adding an oxidizing agent into the starch slurry to carry out oxidation modification treatment; 3) filtering, washing and drying the starch slurry into a powdered semi-finished product for standby; 4) spraying a catalyst and composite phosphate into the semi-finished product to carry out dry modification treatment; and 5) cooling the semi-finished product to a temperature of between 25 and 35 DEG C, adjusting the pH value of the semi-finished product to 6-8 to carry out secondary drying, and crushing the product to obtain a finished product. The product obtained by the method greatly improves dispersibility of the starch slurry, can be easily stewed with stable slurry, cannot be frozen, can completely replace the chemical synthetic slurry to size pure coarse cotton and medium yarns, and can replace the synthetic slurry in large scale to size high grade cotton yarns and union yarns, thereby greatly reducing yarn sizing cost, facilitating desizing, and contributing to environment-friendly waste water treatment.

Description

technical field [0001] The invention relates to a method for preparing compound modified starch, in particular to a preparation process suitable for producing modified starch in textile sizing. Background technique [0002] At present, the modified starch used in the textile sizing industry is one of the three major types of textile size, and the other two types of size are polyvinyl alcohol and polyacrylic acid. Modified starch has been used as the main size in the sizing process of cotton yarn and blended yarn. [0003] In the prior art, the denaturation of starch mostly adopts one or two denaturation methods among pregelatinization, carboxymethyl etherification and cross-linking etherification. Among them: pregelatinized starch, which can swell and dissolve in cold water, has good rehydration property, but its cold viscosity is low and easy to retrograde. Carboxymethyl starch is soluble in cold water when the degree of substitution is above 0.1, the solution is clear an...

AI Technical Summary

Problems solved by technology

[0006] In order to overcome the disadvantages of existing sizing modified starches such as poor sizing cohesion and difficulty in desizing to high-count yarns and blended yarns, the invention adopts wet-process modified starch, which has a large amount of waste water discharge and causes pollution to the environment. The invention provides a preparation method capable of producing compound modified starch. The product produced by this method greatly improves the dispersibility of starch slurry, is easy to cook and the slurry is stable, and will not freeze. It can completely replace the sizing of pure cotton coarse and medium-count yarns Chemically synthesized sizing can also replace synthetic sizing in a large proportion for high-count yarn and blended yarn sizing, thereby greatly reducing the cost of sizing, and at the same time, it is easy to desizing, which is beneficial to the treatment of environmentally friendly wastewater