scope:

This part of ISO 20299 specifies the material and physical property requirements for non-strippable high melting point film for wrapping natural-rubber bales, intended to keep the bales separate during storage. Block natural rubber is prepared by basically comminuting large lumps, washed with plenty of water. It is then dried, baled and packed. The bales are wrapped in clear polyethylene bags and packed into metal or wooden crates. The prime purpose of the polyethylene bag is to keep the bales separate at all times so that they may be easily removed from their packaging for use. However, because it is difficult and uneconomic to strip the film from each bale, an essential feature is that the film should disperse in the rubber compound during mixing. This means that its melting point has to be lower than the temperatures attained in internal mixing cycles, typically 120 °C to 160 °C.