Scraper Coater Application: Preparation of Foam Coating on Fabrics

Foam coating finishing is to evenly and completely coat the prepared foam on the surface of the fabric, adhere to the surface of the base fabric after heat treatment and drying , and then improve the performance of the base fabric to obtain a material with excellent performance.

Blade Coating

The knife coating method is to use a knife to apply a foaming solution on the surface of the base cloth. Place the scraper , mainly use the downward pressure of the scraper to drive the foam, and scrape the foam onto the surface of the base cloth to complete the coating. As shown in Figure

heat treatment

After the coating is completed on the knife coater, in order to prevent excessive penetration and rupture of the foam and retain the complete foam structure, it is necessary to heat-treat the coated glass fiber cloth immediately. Direct high-temperature treatment of coated glass fiber cloth cannot obtain a good cell structure. Therefore, this experiment adopts a two-step heating method and slow cooling treatment to heat-treat the coated glass fiber woven cloth, expecting to obtain Good microporous coating structure.

The first stage is low-temperature drying, the drying temperature range is 120-180°C, the purpose is to evaporate the water in the foam coating to obtain a dry coating structure. At this time, the water in the coating evaporates, and the foam coating solidifies on the surface of the glass fiber cloth, which can retain the cell structure for the subsequent formation of a microporous coating structure.

The second stage is high temperature sintering. The sintering range is 330-380°C. The melting point of PTFE is 327°C. Sintering the coated glass fiber cloth near the melting point of PTFE can remove all impurities in the foam coating and PTFE can It remains stable at this temperature without being decomposed, and fusion bonding occurs between PTFE particles to obtain a PTFE microporous structure with certain mechanical properties and dimensional stability.

The third stage is a slow cooling treatment with a temperature range of 360C-100C to further optimize the structure . According to the experiments of Chunlei Su et al., after heat-treating the polytetrafluoroethylene hollow fiber membrane, place the polytetrafluoroethylene hollow fiber membrane in a cooling oven and continue heat treatment for 10 hours to obtain more pores and better performance. Good hollow fiber membranes. It shows that heat preservation has a certain positive .

Routing

(1) Adopt high-speed-multidimensional stirring rod method to carry out foaming, according to the experimental formula of table 2-5, make a large amount of foams, obtain PTFE foaming coating finishing liquid.

(2) Before the coating test, it is necessary to heat up the hot air dryer and the electric Forced Air Drying Oven to ensure that the temperature in the oven has reached the set temperature and the temperature can be kept stable;

(3) Turn on the automatic film coating machine, pipette a certain amount of PTFE foam, place it evenly on one end of the glass fiber woven cloth, press the switch, the scraper is pushed forward at a uniform speed, and the foam is coated on the surface under the action of the scraper Fiberglass woven fabric;

(4) Remove the glass fiber woven fabric that has just been coated, and immediately put it into a hot air dryer that has reached the set temperature, set the corresponding drying time, and perform the first heat treatment—low temperature drying;

(5) Take it out immediately after drying to obtain a dry coated glass fiber cloth, quickly transfer it to a high-temperature electric Forced Air Drying Oven for processing, heat it to the specified time, and complete the second heat treatment—high temperature sintering;

(6) Turn off the heating device of the oven, so that the oven is in a state of slow cooling, and complete the slow cooling process;

(7) Turn off the oven, take out the PTFE foam coated glass fiber composite filter material, cool down to room temperature, and the entire foam coating process is over.