Concepts in Removal of Carbon Contamination
Concepts in Removal of Carbon Contamination
Molten resin carbonizes if it remains inside a molding machine for long periods
of time or comes into contact with air, resulting in formation of a thin layer
on the surfaces of the molding machine’s cylinder and screw. This partially
cross-linked / carbonized resin film gradually enlarges over time, and at some
point pieces of the film start to peel off. These pieces are the carbon contaminants
that can become mixed in with the molded parts, and represent one cause of
product defects. Since these films adhere so strongly to metal surfaces, they
cannot be removed even with resins such as polyethylene or polystyrene.
CELPURGE combines a component that plasticizes, penetrates, and swells the partially
cross-linked / carbonized film, making it peel away easily from metal surfaces.
Furthermore, this carbide film–removing component is not a surfactant. This
is a big difference between surfactant type purging compounds and CELPURGE.
Concept of filled grades
MA2 is the basic grade of CELPURGE and has superior removal capability of carbon contamination. However, certain partially cross-linked / carbonized layers that have accumulated over long periods of time adhere very stubbornly and cannot be easily eliminated even with MA2. In these cases, filled grades are very effective. The fillers in filled grades serve to strike a blow that can breach the carbide film. Once the film is damaged, the plasticizing component (that differs from a simple surfactant) can easily penetrate. Finally, CELPURGE's core cleaning power cleans up the partially cross-linked / carbonized layers.
Combination of filled grades and MA2
To the extent that fillers are added to increase abrasion, there is a corresponding
decrease in the amount of CELPURGE's original active component. This means
that its ability to remove the remaining carbide film after it has been damaged
by filled grades slightly compromised. In this case, you can compensate by
using MA2 at the same time.
This is especially the case with AG4. This can
be compared to cleaning stuck-on food from a frying pan. The most effective
way is to first go after the stuck-on food with a metallic scouring brush.
Once the food begins to loosen up, you can probably get a better overall “clean”
by finishing off with a sponge. Filled grades and MA2 work in a similar manner
as the scouring brush and sponge. ( Please also refer to “Characteristics
of AG4 and AW2.” )
