VCI masterbatches find applications in films which are used to protect ferrous and non ferrous metal components from corrosion.
Metal components contained within VCI film will be protected from corrosion whilst they are stored or transported to their final application.
Caution must be used when extruding these materials as they can only be processed at low temperatures.
This means that polymer selection for the film is critical to ensure the most benefit is received from the additive masterbatch.
Application Examples
Film extrusion and others.
More details ...
The corrosion of metal surfaces is basically an electrochemical phenomenon which occurs on untreated metal surfaces in contact with an electrolyte such as water.
The resulting electrolytic process, in which electrons from the delocalised systems found in metals flow from areas of higher energy (anodes) to areas of relatively lower energy (cathodes) on the metal surface, causes oxidation (corrosion) of the metal surface.
This process is exacerbated with machined metal parts as the machining and finishing processes leave miniscule peaks and troughs on the metal surface which not only give ideal conditions for microscopic water droplets to coalesce into, but also increase the available surface area for the corrosive reaction to occur on.
The application of barrier layers of non-electrolytic substances (such as oils and greases) has traditionally been used to prevent the process of corrosion. However, this is not an ideal solution as such substances are difficult to apply uniformly, especially in the microscopic peaks and troughs found on finished metal surfaces, they tend to be easily removed by contact with people or packaging and they are messy, which can be a particular problem where electronic control systems are integral.
This problem can be addressed through the use of VOLATILE CORROSION INHIBITORS (VCIs). VCIs are substances that vaporize to release protective entities that adhere to the metal surface in a virtually monomolecular layer and so interfere with the natural electrochemical reaction of corrosion. The disadvantages of oils and greases are overcome as the deposition is in the vapour phase, thus being able to cover the microscopic surface imperfections, and the coating is not readily removed as it is ionically bound to the metal surface.
Wells supplies a multi-metal VCI predispersed and bound within a polymeric carrier which can be added to packaging films during the manufacturing process, thus imparting metal protective properties to the final product. The product has the reference VCI 92094 and is generally available ex stock.
Wells’ VCI 92094 is a polyethylene based masterbatch specially formulated for use in polyolefin films intended for the protective packaging of untreated ferrous and non-ferrous articles. It shows good efficacy against the corrosion of aluminium alloys , brass, copper, silver, solder and zinc as well as iron and steel.
Sealing metal components in film manufactured containing VCI 92094 will protect them from all types of attack including rusting, tarnishing and oxidation.
Due to the vaporisation / condensation cycle in which the active ingredients permeate the product and work to protect hard-to-reach internal as well as external surfaces, VCI 92094 is the product of choice to offer a total protection solution.
Protection can extend for periods in excess of 5 years and customers using films containing the active ingredients in VCI 92094 have achieved excellent protection of automotive and military parts during transport and storage.
Such films have satisfied the conformance criteria for the US Military Specifications MIL-B-22019-C and MIL-B-22020-C.
Films manufactured containing VCI 92094 are transparent, allowing the rapid and easy identification of protected parts, and can be heat sealed and thermoformed as usual. The product does not contain phosphates, amines or nitrites and so is more environmentally acceptable than traditional corrosion inhibitors.
Addition rates will depend on the level and duration of protection required and the type and thickness of film manufactured.
However, for 150 micron polyethylene films an addition rate of 3—6% by weight should give 5 year protection against corrosion.
Refer to the VCI 92094 Product Description Sheet for more usage details.
This information is correct to the best of our knowledge, but we would recommend that users make their own assessment to confirm that the material meets their requirements. We accept no liability for any damage, loss or injury resulting from the use of this information. Freedom from patent rights must not be assumed.
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