In the current papermaking process, in order to impart better physical properties to the finished paper, such as strength properties (surface strength, burst strength, ring compressive strength, etc.) and water and moisture resistance, it is often necessary to use surface sizing during papermaking. The device performs surface sizing on the paper sheet to meet relevant performance requirements. A large number of raw materials are used in the surface sizing process, which is starch. Among them, there are oxidized starch and native starch. The starch used for sizing of cardboard (boxboard, whiteboard and corrugated paper) is mainly native starch, which needs to be modified on site. In order to meet the needs of the sizing process. The following are two commonly used modification methods of native starch and their advantages and disadvantages.

  1. Electroplating Grade Copper Sulfate Pentahydratemodified starch

Add a certain amount of water into the gelatinization tank, and put the starch that needs to be modified into the tank, then add a certain proportion (usually 0.1~0.5% for starch) Electroplating Grade Copper Sulfate Pentahydrate modifier and dilute with water to Need concentration (generally the concentration of starch is 8-12%). Heat to about 95°C, and keep this temperature for 30-60 minutes (set according to the starch type and the viscosity required for gelatinization. During the heating process, the viscosity increases rapidly at about 80°C, and it is necessary to maintain a certain stirring speed. Prevent agglomeration of starch on the wall and bottom of the gelatinization tank). After confirming that the starch is fully gelatinized, transport the starch glue industry to the storage tank for standby, and keep it at a certain temperature (generally 70-80°C is better).

  1. Bio-enzyme modified starch

Add a certain amount of water into the gelatinization tank, and put the starch that needs to be modified into the tank, and then add a certain proportion of biological enzyme modifier (the amount of enzyme added is determined by the activity of the enzyme, the higher the activity, the less the amount added. , The specific dosage refers to the recommended dosage according to the biological enzyme supplier) and dilute with water to the required concentration (generally the concentration of starch is 8-12%). Heat to the temperature required for enzyme modification and maintain this temperature for modification for 10-30 minutes (set according to the type of starch and the viscosity required for gelatinization. During the heating process, the viscosity will increase, and it needs to be maintained at a certain level. Stirring speed to prevent starch agglomeration on the wall and bottom of the gelatinization tank). After confirming that the starch is fully gelatinized, it is necessary to inactivate the enzyme by adjusting the temperature or pH to ensure the stability of the glue liquid. Transport the modified starch glue to the storage tank for later use, and keep it at a certain temperature (generally 70-80°C is better).