Seeking BPA-free Anti-Corrosion Coating For Food Packaging

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A SpecialChem Client is seeking a BPA-free coating that can be sprayed on steel packaging for packaging in contact with food.

The SpecialChem Client wants this product to be able to meet the requirements of a “BPA-NI” (non-intent BPA) package. Meeting this requirement would provide a market differentiation for their products. The market for processed metal cans is immense (approx. 30 billion units), and the estimate of the near term potential for this technology is approximately 1.5 billion of those cans.

The process where this coating would be used involves a metal can part that have been coated with a polyester coating. The parts are then scored with a metal die, which both removes the protective polyester coating in the scored area (approximately 0.3 to 0.6 mm wide by 200 mm long) as well as creating an indention in the steel. Because the can parts will be put in corrosion-causing environments during use, a second coating is sprayed in a narrow path (~3mm x 200mm) to “repair” the exposed metal and overlap onto the adjacent polyester coating. The rust that would result if not protected by a secondary coating is both undesirable from an aesthetic standpoint and has the potential to eventually compromise the function of the metal part.

• Must prevent corrosion of the steel.  Steel can part surfaces are external-facing and subjected to high temperatures (80-150C), pressure (2-4 bar) and immersed in water (a hot-fill or retort canning process).
• The coating must be applied in a fast process (200-500 parts/min) with the application patch per part being about 3mmx200mm.
  • Prefer it to be compatible with a spray nozzle application system
• Viscosity:  10-20 cP although we can adopt the process somewhat (alternative nozzle orifices) to accommodate.  For an immediate solution we prefer a coating that runs on our existing spray equipment.  Second generation solutions could use any variety of coating methods if there is a net benefit.
• Existing cure time:  2-3 minutes at 90 ºC making it safe to handle, typical that full cure takes another 72 hrs at ambient conditions.
• Prefer it to be transparent
• Other cure options acceptable (UV, EB, etc.) but must meet retort packaging regulations for compositional compliance and extractables.
• Electrostatic coating processes that eliminate BPA are available, but a spray coating is a more simple and economical process that we prefer.
• Must adhere to both the coated portion of the metal end (a typical solvent-based polyester coating) and the exposed steel in the score area.
• While it does not directly contact the food during use, coating must be FDA-approved or capable of such approval.  Furthermore, it must not contain any BPA (bisphenol-A) or other chemistries of concern.

• Non-BPA epoxies
• Polyester urethanes
• A water-based, solvent based or 100% solids coating for light gauge steel and coated steel surfaces.
• 1 or 2 part okay

• Anything that contains BPA
• Compositions that cannot meet FDA requirements (heavy metals, excessive extractable, compositionally non-compliant, etc.).  
• Must not create off-tastes or odors.

The SpecialChem Client wants the solution before Q4 2016.

FDA compliance for retort packaging regulations is a must.  We can help evaluate compliance with our internal resources but we also use 3rd party legal counsel to protect confidentiality of coating formulations.

Current target market is 1.5 to 2.0 billion parts with each part needing 2-8 mg of coating per part (using existing coating as an example).

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