Mould Release Agents: An Overview

Author: Raju Mehta

The main purpose of using mould release agents is facilitating easy removal of any composite part from the mould as well as stop stick ups. These are applied on top of mould surface by spraying, brushing or wiping it over the surface.

There are some agents which need not be removed while in case of other types of agents it becomes essential to wipe them off when the task of removing composite part finishes. Our aim here will be to have a detailed look at these agents and analyze the type of such agents that are available and their features.

Release Agents and Their Types

Usually there are five types of mould release agents that are available, these are:

Polyvinyl Alcohol (PVA): PVA is normally available as a clear blue or red color liquid and when it dries up, a plastic film gets created which then covers up the mould surface. This type of agents is usually used in a situation in which there could be some problem with the release.

Wax Systems: These are in the form of paste or liquid and consist of synthetic wax, carnauba wax and any other natural wax. The main application areas of these wax systems are in different wet lay processes and in curing processes that are carried out in ambient temperature.

Semi Permanent Polymer Systems: These are also called polymer release agents and are created using polymer resins that are generally dissolved in a solvent.

Hybrid Systems: As the name suggests, these combine wax and polymer systems together.

Internal Release Additives: Normally such additives are included in sheet moulding and dough compounds.

A Look at the Features

Let us now go through the main features of such agents:

  1. These are excellent release properties and in addition to it they offer quick demoulding.

  2. Such agents are beneficial for use in various compound moulding cycles.

  3. They help in reducing fouling, enhance wall slippage and offer improved mould flow.

  4. Some of the agents which are silicone based are in the form of aqueous emulsion which makes it easier to handle and apply them.

  5. Another good thing about them is that such agents have very good freeze thaw stability. Apart from that they also do not cause any type of creaming or extreme oiling.

  6. These release agents also have very good dilution stability and due to it adequate concentration can be used with no wastage.

  7. It is quite easy to apply them through brushing, dipping or spraying even for complex moulds.

  8. Another noteworthy feature of the mould release agents is that they have quite low surface tension and also have good wetting properties on top of mould surface.

  9. The film that forms is normally durable and also heat stable.