Additives mould-release agents

Other surface active ingredients which may be found in plastic materials and suffer loss into product by solution, surface abrasion, etc. include anti-static additives, slip additives, mould release agents, etc. 

Polymer additives - mould release agents, plasticisers, antioxidants and UV absorbers, with molecular weights extending beyond 1000 - are generally unsuitable for GC or liquid chromatographic (LC) analysis because of their low volatility, lack of chromophore or thermal instability. 

Many rubber compounds have a tendency to stick in the mould cavity after vulcanisation and require some type of mould release agent. The substances used are surface-active materials such as detergents, soaps, wetting agents, silicone emulsions, aqueous dispersions of talc, mica and fatty acids, applied by spray or brush. Alternatively, dry types based on polytetrafluoroethylene or polyethylene, usually carried in a solvent, can be aerosol applied. An alternative is the addition of an incompatible material to the rubber compound which will bleed to the rubber surface during vulcanisation. 

Migration of additives such as plasticizers, internal mould release agents... Painting defects can appear a long time after painting. 

Chemical additives on the surfaces of container closure system component fabrication machinery, such as mould release agents, antistatic and antislip agents, etc. 

It should be noted that constituents in terms of plastics could include residues (from the polymerisation process), additives (ingredients added to enhance or modify certain properties), processing aids (ingredients added or used to assist in a fabrication or conversion process, e.g. mould release agents, lubricants), and master batch constituents (if a master batch is used). 

The monograph states that the nature and amount of additive used will depend on the type of polymer, the process used to convert it into a container and the intended purpose of the container. Approved additives include antioxidants, stabilisers, plasticisers, lubricants, colour and impact modifiers. Anti-static and mould release agents can be used only for containers for oral and external preparations. Specific permitted additives are given in the specification for the material within the pharmacopoeial monograph. 

Processing aids cover chemicals used for specific purposes to assist processing. Some are identical to those included under additives, e.g. lubricants, antioxidants, mould release agents. The last of these may be regularly sprayed onto moulds and may occasionally lead to poor label adhesion or oil-like contaminants. 

Release Agent—An additive which promotes release see also Mould Release Agent. 

Certain lubricants and slip agents are vegetable-based, because avoidance of the usual animal sources is essential in certain food packaging markets. Chemax offers vegetable-based stearate additives called Maxomer Lube , and Kemamide ELO from Crompton is a vegetable-based GMO-free erucamide, used in bottle closures where odour and taste are particularly important. It is a mould release agent for polyolefins and is said to be fairly resistant to oxidation. 

Mould release agents and processing additives are engineered to improve the production process and product quality. They facilitate optimum demoulding of the contents from the mould and the release agent should not transfer from the mould surface to the moulded part. Parts that are easily removed from the mould exhibit an attractive mirror-like finish and with less mould maintenance and wear, less cleaning of the part is required. 

Various workers have reviewed the application of IR spectroscopy to the determination of additives [16, 17, 18]. Other recent applications of IR spectroscopy include the determination of slip agents in PE [19], ethyl acetate and ethanol in HDPE [20], stearic acid in polystyrene (PS) [21], talc, antimony trioxide and decabromophenylether flame retardants in polyvinyl chloride (PVC) [22-24], mould release agents [25] and binders in aged paint film [26]. 

The properties of PC s can be adjusted to the requirements of customers by copolymerization with other polymers and/or addition of additives, e.g. mould-release agents, flame retardants, light stabilizers, reinforcements, heat stabilizers, colours. 

Murphy, I, Additives for Plastics Handbook, Chapter 17 Lubricants, mould release agents, slip, anti-block, Elsevier, Oxford, 1996. 

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