EcoFlex coatings are aqueous dispersions of vermiculite platelets in polyvinyl alcohol (PVOH). The platelets are 1-3 nanometers thick and 10-30 microns in breadth, yielding an average aspect ratio (breadth-to-thickness) of ~10,000:1.

The platelets are maintained in singularized format when dispersed into the PVOH resin and aligned in the plane of the coating when deposited on a film substrate, such as polyethylene terephthalate (PET). The dispersed platelets create a tortuous path for gas molecules, enabling an extraordinarily high gas barrier in a very thin layer (0.2 - 0.5 microns dry) with excellent bond strength, clarity, and flexibility.

The proprietary formulation also dramatically improves the moisture-resistance of the PVOH resin.

The key technical difference between EcoFlex coatings and past attempts to use nanoclays for barrier enhancement is that the clay platelets remain in a singularized format not only when dispersed in the resin, but also during and after deposition. Not only does this achievement enable the tortuous path required for the high gas barriers, but it also enables the cohesive strength necessary for multi-layered packaging film structures.

EcoFlex coatings can be applied to a variety of substrates (films, bio-films, papers, and rigid structures) using a variety of standard printing and coating equipment (e.g. rotogravure press, flexographic press, slot die coater, spray coater, etc.).

EcoFlex coatings are manufactured as a two-part system

• A masterbatch of carrier resin and additives
• A water slurry of vermiculite platelets

The two parts are mixed gently under ambient conditions just prior to applying the coating.

There are several important operating parameters to consider when applying NanoSeal coatings to a film substrate:

• For anchoring the coating on PET, the minimum surface energy of 45 dyne-cm is recommended. For nylon and polyolefins, a primer layer is required.
• Standard anilox rollers can be used. A smoothing bar is also recommended.
• NanoSeal coatings have very low solids content (<10%), so adequate drying capacity is required.
• The heat from drying ovens initiates PVOH cross-linking. Curing, and resultant bond strengths, will continue to improve for up to 7 days.
• A higher-viscosity version of the formulation is available for the application using a flexographic press to prevent “slinging” of the coating.
• Because the coating does not heat seal to itself, a sealant layer is required (e.g. polyethylene, cast polypropylene). For example, a polyethylene sealant layer can be extrusion-coated directly onto the NanoSeal coating or laminated to the coating using a solvent-based or solventless adhesive system. Alternatively, the sealant layer itself can potentially be used as the coating substrate.
• Solvent-based inks should be used; water-based inks should be avoided.

Performance 

EcoFlex coatings deliver 10-200 times the gas barrier of competing for clear materials, such as EVOH and PVdC (see figure at right). Additionally, is not corrosive like PVdC, has better moisture resistance than EVOH, and is not prone to flex-cracking like AlOx or SiOx.

Cost Savings 

EcoFlex coatings are formulated with different loadings of vermiculite to enable different levels of the gas barrier, depending on the requirements of a given packaging application.

In general, NanoSeal coatings yield package structures that are 10-50% less expensive than traditional package structures of comparable barrier performance. Future EcoFlex products will enable even more significant cost reductions by incorporating platelets into other materials (e.g. adhesives, primers, sealant coatings, etc.), thus eliminating entire package layers.

Environmental Benefits 

EcoFlex coatings address a number of environmental concerns commonly associated with barrier materials.

First, they enable significantly better gas barriers than alternatives while using 80-90% less material (reducing the amount of packaging material is the US EPA’s top objective in addressing landfill issues).

Second, EcoFlex coatings deliver barriers without the use of free chlorine, which has been increasingly targeted for elimination because of its processing and disposal hazards.

Third, scrap packaging coated with EcoFlex coatings can be re-ground and blended into virgin resin for re-use, unlike some barrier materials.

And finally, NanoSeal coatings do not inhibit the bio-degradability of compostable packaging. Additionally, planned EcoFlex products include barrier coatings using fully bio-based resin systems.