Product: Barrier Coatings for Multiple Materials
Development Stage: Method Established
Primary Inventors: Margaret Joyce and Thomas Joyce PhDs, Paper & Chemical Engineering Departments
Scientific Publication: Jayaraman, et al., International Hygienic Coatings Conference Proceedings, Brussels, Belgium, July 2002
License Status: License Available
Patent Status: Granted, US 6,942,897 B2
Reference: 1996-01
Materials such as; paper, wood, wallboard, fiberglass, plastics, metal, glass, ceramic, stone, concrete and asphalt, often need to be impervious to water, oil, grease or even oxygen. These materials are commonly covered with a barrier coating to prevent substance penetration.
For paper products, fluorochemicals are currently being used to provide barrier properties. Fluorochemicals are problematic because they are expensive, and they accumulate in the environment. Waxes and synthetic plastic films are also used as barrier coatings for products. Although waxes confer excellent barrier properties, they must be applied at relatively high coating weights and cannot be easily glued to or over-printed. Plastic films confer good barrier properties but are expensive and difficult to use. They also present recycling and bio-degradability issues.
Because of these problems, there is a demand for coatings that are easy and inexpensive to manufacture and apply, have good resistance to water, oil and grease, and are biodegradable or easily recycled.
Technology Description
Researchers at Western Michigan University have developed patented coating methods for a variety of materials. The coatings are inexpensive, environmentally friendly, easy to produce and apply, and impervious to water, oil and grease.
They have found that nanoparticle pigments, around 100 nanometers in size, are effective barrier coatings. They can consist of; talc, calcium carbonate, clay, silica, alumina, or plastic particles. The nanoparticle pigments can be selected based on the intended use of the coated material and are commercially available.
A binder, and a carrier made of water or a water-alcohol mix, are mixed with the nanoparticles at room temperature to create the coating solution. Using water as the coating solvent makes the coating and drying process straightforward and more environmentally friendly.
Calendaring can be performed on coated papers as a final finishing step, after the coating is dried.
A coated paper produced using nanoparticle pigments has a Gurley permeability measurement that increases from around 500 seconds before coating to 8,000 to 12,000 seconds after coating.
Potential Benefits
• Provide superior penetration protection against water, oil & grease
• Uses commercially available components
• Water based barrier coating that is easy to apply and to dry and is environmentally friendly
• Permits normal paper finishing processes