Control of the solid content of the immersion bath
The concentration of solids in fluoropolymer coating fluids can be easily determined by observing a few points.
What is needed?
1 Precision balance with a display accuracy of 0.001 g.
1 Weighing Pan - Disposable item made from aluminum foil about 70mm Ø
1 5 or 10 ml syringe, reusable
What are we going to do?
1. Scale has been switched on for at least 5 minutes. Without loading with tare display to 0.000 button pressed.
2. Place the pan and empty syringe on top and record the weight. (Result 2)
3. Fill the syringe, place it on the scale together with the pan and note the total weight. (Result 3)
4. Empty the contents of the syringe very carefully into the pan and set the syringe aside.
5. Allow the pan to dry out at room temperature for approx. 10 hours - preferably overnight.
6. Place the dry bowl and syringe back on the zeroed scale and record the weight. (Result 6)
How do we get the result?
The calculation is carried out in such a way that the tare weight from 2. is subtracted from the gross weights from 3. and 6. and the two results are set in relation to one another in order to determine the percentage.
|
Result 6 - Result 2 |
x 100 = Percentage of solid |
|
Result 3 - Result 2 |
The solids content should be between 1.8 - 2.2%.
If the solids content falls below 1.8%, the solvent that evaporates from the bath and condenses in the cold trap must be collected separately. To do this, the valve for the condensate branch on the coating systems must be opened. If the solids content rises above 2.2%, the condensate must be returned to the bath. The valve on the systems must then be closed. In addition, the concentration can be reduced with a solvent provided specifically for this purpose. The solids content can also be increased by adding a 10% concentrate.
What else should you know?
When emptying the syringe into the bowl, some liquid tends to squirt over the edge of the pan. To avoid this, you can poke a small hole in the top of the syringe and then pull the syringe plunger up past the hole to slowly let the liquid slide onto the pan.
