Many serious film defects can be caused by hard resin particles, gels, residual metal catalysts and fibers. Similarly, haze, which decreases distinctness-of-image, can be a problem in transparent coatings. Over-sized resin particles also increase cure costs in conventional and in UV systems by increased oven costs or the need for higher levels of costly photo-initiators. An eight-day study at three controlled temperatures was performed on a water-borne acrylic resin and a solvent-borne polyester resin to determine the impact of four general filter types, i.e. low-depth vs. full-depth and compressible vs. non-compressible on haze, gel and particle removal. The manufacturers rated all filters as 10 microns. The effluents were quantitatively and qualitatively evaluated using a turbidimeter, a haze meter, a microscope, a light-box and a digital camera. Filter residues were analyzed using spectroscopic instrumentation. The filter type that performed best was of full-depth, non-compressible, bi-component construction.
展开▼
