The filter pressure value (FPV) test is essentially an objective test of the dispersion performance of the masterbatch. Regarding the white masterbatch, if the dispersion performance is better, it will be more conducive to showing the good tinting strength and white uniformity of titanium dioxide in the finished products, and it will also help to increase the toughness of the finished products.
The principle of filter pressure value test is: set the filter in front of the extruder, and then fill the material for testing. First test the melt pressure value in front of the filter when pure plastic resin materials (such as PVC) are extruded, and record it. Then put in the prepared sample according to the specified proportion. Due to the color masterbatch added to the resin sample, some large titanium dioxide agglomerates during the plasticizing process, which will cause blockage of the filter when flowing through the filter. The test device will record an increase in the melt pressure value in front of the filter.
The difference between the sample filter pressure value and the pure material reflects the dispersion.
The worse the dispersion, the faster and larger the sample pressure value increases.
The above theory can be indicated as a formula:
Which industries have high requirements for filter pressure value testing?
Because the filtration pressure value (FPV) test reflects the dispersion of pigment masterbatch, some special industries have higher requirements for filtration pressure value testing. For example:
spinning industry. If the dispersion of the masterbatch is not good and the pigment particles are too large, network blocking will occur. The entire spinning line has to stop.
Film products. Some special film products require uniform color distribution and good surface gloss. The dispersion requirements for pigment masterbatch are also very high.
If filter pressure value testing is not used, is there any other way to test the dispersion of titanium dioxide white masterbatch?
The other simple methodes to test the dispersibility of titanium dioxide in plastics
Plastic blown film:
Titanium dioxide white masterbatch is blown into a film, and then evaluated by observing whether there are agglomerated particles of color masterbatch in the film and the uniformity of color distribution.
Color plate + SEM. In this method, titanium dioxide white masterbatch is injection molded into a thin sheet, and then the dispersion of titanium dioxide in the sample is directly observed through a scanning electron microscope.
Melt index test: The dispersion of masterbatch is related to the melt index. Therefore, this method can also indirectly indicate the dispersion of titanium dioxide.