Gas assisted injection moulding process now has
another modification; wherein Carbon Dioxide (CO2) is
introduced in melt through injection cylinder in addition to the
The Amotech process developed by Asahi Kasei Corporation,
Japan involves injection of CO2 gas at about 2-3% level
and at 5-10Mpa pressure in injection cylinder.
CO2 gas acts as plasticizer and enhances flow of the
CO2 gas gets dissolved throughout the melt and gets dispersed
in the atmosphere at a later stage. The structural integrity of
the moulded part therefore does not get affected. The major benefits
are superior surface finish and perhapssome scope of reduction in
wall thickness of the moulded parts.
The process has been evaluated in Polystyrene and
Acrylic polymers in injection moulding machines upto the size of
500-ton capacity. Most of the gas disappears from the moulded parts
within a day. No gas is detected at all on storage of the products
after a week.
Target applications are:
||Portable information terminals
The Amotech process is available for license
and could cost under $50,000. This cost includes gas supply equipment
and special screw that introduces gas in the melt.
It will take some time to assess the success of this new technology.
|Source: Modern Plastics International
- March 2001