Raw material for Rotational Molding
LLDPE ( Liner Low density Polyethelene ) /MDPE (Medium density Polyethelene) / HDPE (High density Polyethelene) are being used with density of 0.92 to 0.95 gms/ Cm cube and Melt Flow Index in the range of 3 to 4.5 gm per 10 minutes. To produce the good quality water tanks by Rotational Molding, the material should have following properties.
Other Ingradients
The original LLDPE granules are of natural colour which have to be converted in to either black, white, blue or other colours as per requirement of final product. To produce the coloured granules , basic LLDPE granules have to be mixed with colour concentrate which are called as master batches.
These master batches are readily available in market which are to be added alongwith LLDPE.
The master batch should be of grade which is LD based. The master batch with antioxidants are more preferred. Anti oxidants protects the material from oxidation during the molding process which helps to avoid the pin holes on surface of finished product.
Incase of black master batch, carbon contents are very important. Carbon contents act as UV stabilizer. It helps to improve the life of tanks if tanks are exposed to sunlight for longer period and to avoid the crack on tanks.
Some other common additives like flame retardants, anti static agents, foaming agents, are also used as per requirements.
