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Technical Information >> (3A) MEQ Measuring of Electrophoretic lacquer
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SHINEX Emulsion Stabiliser (MEQ)
Maintain MEQ > 35. MEQ reading of 40 to 45 is ideal. Addition of 10mls MEQ Replenisher to 50 litre bath will increase MEQ by 2 (0.2mls/litre bath). It increases neutralisation and slows down coating process. The addition could be even as 50ml for 100 litre bath, directly added to bath as it would not damage the operating tank.
Measuring MEQ
1. Chemicals and Apparatus required:
0.1m (Molar) Methanolic Potassium Hydroxide
Rinse Aid
2 Buffer solution (pH4 and pH9)
2. Apparatus:
pH meter
50ml Burette
Spatula
250ml Beaker
3. Process:
Weigh 50 grams of well stirred sample (bath solution) into a 250ml beaker.
Add 10 grams of Rinse Aid (up to 15 grams if the solid is expected to be above 12%).
Make up weight in beaker up to 200 grams with DI water.
Calibrate the pH probe using buffer solutions.
Immerse probe into beaker, agitate and titrate with 0.1 molar ethanolic Koh with constant agitation, until the pH reaches pH 9.0
Note the number of mls of KOH. Required = Titre A
4. Calculation:
MEQ/100 grams = Titre A x2
Corrected MEQ = MEQ/100 x 10% solids of bath
(divided by) % solids content
Example for MEQ 50 @ 8.5% solids
50 divided by 8.5 multiplied by 10 = 58 corrected MEQ
5. Comments:
Agitation should be stopped when taking pH reading end point to prevent false reading due to agitation.
Care should be taken not to block pH probe sensor with precipitate.
It is advisable to carry out a determination in triplicate to ensure accurate results
6. NOTE
The use of the magnetic stirrer ensures that the degree of agitation is always constant, so that any off-set in reading is constant, and so can be ignored.
If a pH meter is not available, it is possible to use phenolphthalein as the end point indicator. However, this is only possible with non-coloured.
For more information write to us on
info@shinextechnologies.co.uk
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