Quality of the chips for microfibre
Demands on polymer quality during the production of microfibres are very stringent. For example, the
polyester composition has to be consistent and it should not contain foreign matter. [2] The molecular
weight distribution should also be narrow and short-term viscosity must be kept as consistent as
possible. Polymer chips need to be smooth, tailless and identical in shape/size. As microfibres are a
high-value product, the use of ‘off-quality’ chips should be avoided, as they would otherwise cause
undue problems in processing. It is advisable to use chips of the best available quality for the
production of microfibres.
It is also important to maintain the quality of the product in all subsequent steps. The drying process
should be as consistent as possible, and chips must have an even residence time. The moisture
regained of the dried chips should be less than 0.005%, to minimise the hydrolytic degradation in
molten stage. Thus specifying the precise moisture level in the dried chips is essential for trouble-free
production of microfibres. For drying quality chips, a continuous drying process is better than batch
drying.