Pd-p140.docx

PD-P140 is water based intermediate product. That was manufactured on a laboratory scale, and achieved the appropriate grind. It was manufactured using a simulation of a mono-mill; therefore for scaling up production, it was going to be using a Mono-mill, located within the factory. The batch size was going to be 50 Litres, and available to us where a 5 litre and a 20 litre mono-mill. As the batch was so large, the 20 litre mono-mill was chosen by our production controller. As the process and the product materials where not fully known to us, and the final product was a temperature sensitive product, we made the decision to attempt to keep the temperature below 40 degrees centigrade if possible. The formulation consisted of a pre-mixed stage of pigment and binder, then a washings stage of binder. This was to achieve the most out of the mill drop, and minimize the amount of wasted material. The mono-mill was prepped for Water based milling; this was done by using an aggressive solvent, such as MEK, to ensure all solvent borne products were removed from the mill. Then it was washed out with a water soluble solvent such as Isopropanol. This was done twice, once to remove the solvent, then once as a cleaning process before being given a wash with water. After each stage this was drained, thoroughly given 5 to 10 minutes to ensure all fluid had drained out before going onto the next stage of cleaning. Once the mill was cleaned, and left to drain for the final time, the raw materials where collected and weighed out. The pigment was weighed into paper bags. The liquid binder was weighed into plastic drums ready for pre-mixing. The powder was added under a mixer, and mixed in with the binder, until a relative solution was achieved. This was then transported to the mono-mill, and poured out, as only a small amount of the total premix was able to fit into the monomill the remainder was put back on the stirrer to keep it from settling. The mono-mill was started, and the product left for a period of 30 minutes before the first grind check and temperature check. This came out at over 100 microns, and a temperature of 35 degrees centigrade, therefore not good enough, and raising too high. So the mono-mill was reset, and the water jacket was turned on. Periodically checking the mono-mill grind and temperature to ensure nothing went amiss. After 150 minutes the mono-mill was checked, and the temperature read out shown was above 40 degrees centigrade. Due to the paint getting to theses temperatures it had caused condensation against the lid, and this condensation had started to corrode the mono-mill. The grind specification at this point was 20 microns, still above the 5 microns required, but the mono-mill was not going to be able to continue without potentially contaminating the batch. Therefore the mono-mill method was not an achievable method. Therefore we were going to switch the process from the mono-mill to the Netzch mill. Located within our production area we have 4 litre and 20 litre mills. Available to us at the time was a 4 litre mill; therefore we had to use that. As only 1 pot had been ground in the mono-mill, the batch was remixed together, giving us a grind

specification of above 100 microns across the batch still. Going into the mill, it was pumped into the mill, then the netzch was started, and the paint was fed through single pass at a time, the temperature of the product started to increase almost instantly. Rising up past 40 degrees centigrade and continuing on a rise. This was out of our hands, as the water jacket for the mill was already on full. Therefore it was trialled, seeing how the product would behave when milled, if the temperatures rose above the 40 degrees centigrade. The grind was checked after each pass had been completed. Giving us data to input into our mill chart for the use of the netzch, temperatures, grind, and total time for each pass where recorded. As each pass came out, the product was taking longer to mill each time. Water was evaporating from the product due to the temperatures the milling was achieving. This was unavoidable, but as the grind needed to be achieved we continued with the job. The total number of passes we conducted where 4 passes. At the end of these 4 passes we noticed that the grind was not going beyond 80-100 microns, and the temperature was continuing to rise beyond the 40 degrees, up to 60-65 degrees centigrade. As this would take a very long time to achieve the grind, and the mill where not to be left unsupervised, this was not an achievable method either. Therefore a switch to a ball mill was going to be our final attempt. This would eliminate any chance of temperature rising, as the work done was done at an ambient temperature, and no mechanical work was put into the product. We have a 20 litre and 100 litre ball mills. As we had a 50 litre batch size, we opted for the 100 litre ball mill. We added the washings stage to our pre-mixed stage to create a better consistency for the ball mill, and were going to have to take a hit on our yield as to what we achieved from the mill. The mill was ran for 48 hours, before being checked for grind specs. After 48 hours, the grind was still above 80 microns. Therefore it ran for a further 48 hours, before being checked, and seen as 50 microns. At this point we started running it for another 48 hours, thinking this would be the final time. After this run, the grind check was 20 microns. Still not quiet the 5 microns we had hoped to achieve. Therefore the mill was ran for a further 24 hours, giving a total of 7 days on the mill. The grind did not move below 20 microns, so a sample was taken from the product, and the finished product was made up from this sample. This test product was applied, and tested to see if the colour changes where achieved correctly, and at the right points. When this was tested, and the results were positive, and show that the finished product can still be made, and the particles where not noticeable within the film, the mill was drained, and the yield noted down. This process shows that as the grind was not being achieved the method of product was being modified as the product was going.