Mould temperature liquid silicone rubber

Haberstroh et al. (2002) modelled the injection moulding of liquid silicone rubber via the use of curing kinetics, flow models and the pressure-volume-temperature behaviour. 

The early 1980s saw considerable interest in a new form of silicone materials, namely the liquid silicone mbbers. These may be considered as a development from the addition-cured RTV silicone rubbers but with a better pot life and improved physical properties, including heat stability similar to that of conventional peroxide-cured elastomers. The ability to process such liquid raw materials leads to a number of economic benefits such as lower production costs, increased ouput and reduced capital investment compared with more conventional rubbers. Liquid silicone rubbers are low-viscosity materials which range from a flow consistency to a paste consistency. They are usually supplied as a two-pack system which requires simple blending before use. The materials cure rapidly above 110°C and when injection moulded at high temperatures (200-250°C) cure times as low as a few seconds are possible for small parts. Because of the rapid mould filling, scorch is rarely a problem and, furthermore, post-curing is usually unnecessary. 

HTV and liquid silicone rubber LR, are used in moulding at elevated temperatures (press, transfer or injection moulding). 

Figure 11.6 shows the strong dependence of solidification time for the thermoplast and/ or curing time for the liquid silicone rubber from moulding temperature. It is not intended to be symmetric as it may differ for various pairs of materials. 

Shorter curing times in the silicone cavity lead to shorter contact times for the thermoplastic. The shorter the contact time, the higher the temperature of the silicone cavity that can be used without it being critical for the plastic substrate. In other words, the temperature of the silicone rubber mould strongly depends on the speed of curing of the liquid rubber used in the processing. 

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See also in sourсe #XX -- [ , , , , , ]

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