Modified starch and preparation method and application thereof

Abstract

The invention relates to modified starch as well as a preparation method and application thereof. The modified starch is mainly prepared by reacting a zwitterionic starch complexing agent with starch,the chemical structure of the zwitterionic starch complexing agent comprises i) one or more hydrophobic groups, wherein at least one of which is capable of reacting with starch to generate an inclusion complex, and ii) one or more hydrophilic groups,wherein at least one of which is an anionic hydrophilic group, at least one hydrophilic group is a cationic hydrophilic group; and the hydrophilic groups are connected through chemical bonds to form one tail end of a molecular structure, and the hydrophobic groups and the hydrophilic groups are located at the two ends of the same molecular structure respectively and connected through chemical bonds to form an asymmetric and polar structure. When the modified starch is used for papermaking, the retention rate of the starch in paper can be increased, so that the strength of the paper can be improved, the loss of the starch in the pulping and papermaking process is reduced or even eliminated, and the COD emission is reduced.

Description

technical field [0001] The invention relates to the technical field of papermaking and starch modification, in particular to a modified starch and its preparation method and application. Background technique [0002] Starch is a natural high-molecular carbohydrate that widely exists in seeds, stems or roots of plants. It is abundant in resources and low in price. It is widely used in industries such as industry, food, textiles, papermaking, feed, medicine, construction, and drilling. . Starch is one of the most important raw materials for papermaking. It is often the fourth largest component of paper and board by weight, after cellulose, inorganic fillers and moisture. Cultural and packaging paper and paper plates are major users of starch. The consumption of starch in the papermaking industry in the world is about 5 million tons, which is about 1.6% of the total output of papermaking and paper plates in the world. [0003] China's paper production has maintained rapid d...

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Problems solved by technology

The above methods have disadvantages. The cationic starch produced by the wet method not only consumes a lot of water, but also the discharged sewage pollutes the environment. The wastewater is difficult to treat, and the alkaline chemicals used can lead to starch degradation and transformation. low rate

Dry production is to mix starch with reactive chemical reagents, dry to almost anhydrous and then react at 120-150°C. Although the pollution is less, the disadvantages are low reaction conversion rate, relatively high requirements for equipment and technology, and high production costs. , production conditions are difficult to control, starch products are easily over-gelatinized, which affects product quality, and the reaction cycle is long and energy consumption is high; the organic solvent method uses a large amount of water-soluble organic solvents (such as methanol, ethanol, isopropanol, etc.) in the preparation process ), disperse the starch in it to form a slurry, and react with the cationizing agent to prepare the cationic starch

Due to the use of a large amount of organic solvents, this method has the disadvantages of high production cost, poor safety, and easy pollution of the environment, so it is rarely used in industry.

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