Corrugated production bad factors and adjustments (4)

1. What are the main reasons for paste preparation?

Water, caustic soda, starch (corn flour or tapioca flour) borax, viscosity stabilizer (stabilizer), glue reinforcement (crosslinker), etc.

2. What is the main role of caustic soda?

Starch granules have a strong cohesive force, water molecules do not easily penetrate, and the molecules of water must be taken into the starch granules by the strength of caustic soda, so that the starch granules expand, generate viscosity, and lower the gelatinization temperature.

3, what kind of starch? What is the difference?

The main starches are corn flour and tapioca flour, which can be mixed. The main differences are:

Maize powder: The particles are small and must be expanded to a certain degree to produce stickiness. Therefore, the use of a slightly higher viscosity, the drying rate is slower, so the trimming machine out of the paste is wet, in general, the consumption of paste slightly high.

Cassava flour: Slightly larger lumps, the paste will produce stickiness, so the use of viscosity paper, the drying speed is faster, so the trimming machine out of the paste is dry, in general, the amount of paper consumption slightly.

4. After the secondary caustic soda is added, it needs to be stirred for 25±5 minutes to allow the viscosity to reach the standard. Why?

Because there is ample time, the starch granules are evenly swelled, and the viscosity is relatively stable. If the viscosity rises too fast, some starch granules will expand excessively, some along the unexpanded, the viscosity will change greatly, and the amount of caustic soda must be reduced. If the time is too long, It is difficult to increase the viscosity, and the heat generated by stirring must be used to increase the activity of caustic soda to allow the starch granules to swell. However, due to insufficient caustic soda, the viscosity of the caustic soda will be reduced during use, so the amount of caustic soda needs to be increased.

5. How to measure gelatinization temperature? What does it mean?

The paste was placed in a beaker, placed in water at a temperature of 85-90°C, and the paste was stirred with a thermometer. When the viscosity rose rapidly, the temperature at that time was the gelatinization temperature. The gelatinization temperature indicates the temperature of the paste at the time of maturation. In terms of chemistry, it indicates the content of the caustic soda, the more caustic soda, the lower the gelatinization temperature, the lower the caustic soda, and the higher the gelatinization temperature, the higher the gelatinization temperature. Temperature measurement, to adjust the amount of caustic soda.

6. How much is the paste temperature correct? What is the relationship with climate?

In general, the summer gelatinization temperature is 57-59°C and the winter gelatinization temperature is 55-57°C. Because of the high paste temperature in the summer, paper and mechanical heat are enough, and it is easier to fit. Therefore, the gelatinization temperature is higher and the viscosity is relatively stable. Due to the cold weather in winter, the temperature of the paste is also low. Therefore, it is necessary to reduce the gelatinization temperature and reduce the heat required for the paste maturation in order to facilitate the fit.

(to be continued)