Since its widespread appearance on buildings and public and private transportation systems in the 1960s and '70s, graffiti has served to illustrate a particular type of sociological phenomenon: defiance amplification. Namely, the more attention bad behavior gets, the more some people want to do it.



Graffiti from vandals strongly impacts the perceived value and aesthetics of a building or motorized conveyance. Obvious graffiti is immediately characterized as sloppiness on the part of the owner, lack of maintenance and "unsafe." When building architects, transportation-system designers, and owners consider new design or maintenance of buildings, the need for an easy-to-maintain coating with an expected life of 20-30 years is a constantly desired (though rarely realized) objective. When encountering the likelihood of repeated graffiti with standard coatings, regular cleaning and vigorous maintenance must be planned and scheduled continuously, at significant long-term cost, to say nothing of surface degradation to the building or conveyance itself. Any coating that can provide a stain- and graffiti-resistant surface, that cleans readily for decades without destroying the surface coating itself, that reduces substantially the ever-increasing cost of maintenance, and that makes a major contribution to maintaining the initial investment, can save time and effort.

This article presents the application of a novel fluoropolyether polymer resin as an anti-graffiti coating. This new material offers architects and coatings specialists a new method for repeatedly dissolving graffiti on outdoor surfaces as it occurs, without degrading surfaces or their coatings, and without sacrificing coating durability and weathering properties.

Resin Structure and Synthesis

Fluoropolyether (FPE)-functional derivatives, obtained through a photo-oxidation polymerization multi-step process, can now be used as starting materials for the production of fluorinated polymers and coatings.

The final product is an FPE, which, through a natural synthesizing process, becomes what is known as a "prepolymer." This new fluoropolyether coating resin is named Fluorobase(r) Z 1074.

Because of the flexibility of molecules in the backbone of the FPE chain that forms the basis of the resin, it can tolerate years of continuous thermal transitions from as cold as -130˚F (-90˚C) up to ambient temperatures. When formulated in a coating, Z 1074 application exhibits a tack-free interior or exterior surface at moderate ambient temperatures, and superior mechanical properties.

The resin ambient cures in a range of temperatures as low as 36˚F (2°C). Substantial coating thicknesses as high as 70-80 microns can be obtained on surfaces without any bubbling of the coating. Coatings present the contemporaneous presence of a "rubbery" surface once applied, and a hard, durable finish when dry.

Once applied to a structural surface, coatings with Fluorobase Z form a tough, durable - yet invisible - surface film that lasts for decades. Structural surfaces on which coatings with the resin have been applied exhibit a greater tendency to be self-cleaning. When cleaned with ecologically acceptable water-based or solvent-based cleaning solutions, graffiti wipes away without a trace. Surface color retention, desired gloss levels and reflective qualities inherent to architectural or other coatings that employ Z 1074 are unaffected by repeated cleanings. Coated surfaces that contain it are impervious to acid rain, airborne pollutants, fuel spills and other forms of chemical exposure. The level of color and gloss on surfaces remains unchanged by coating surfaces with a Z 1074 paint - year after year, even after frequent removal of graffiti. Table 1 describes typical properties of Z 1074.

The optical properties of Z 1074 paints can be highly diverse, with excellent hiding power of imperfections in the surface. The excellent mechanical properties of Z 1074 are influenced by their adhesion to the substrate. They are superior when epoxy, polyester and polyurethane primers are used, less so when directly applied to metals and glass.

Durability characteristics of Z 1074 coatings have been evaluated by chemical resistance spot tests and accelerated weathering by UV light exposure (QUV-B test, light 4h. at 60°, dark 4h. at 40°), as well as by salt fog tests. Results are summarized in Table 2.

A relatively high bulk fluorine content of any Z 1074 coating is the main parameter that has a positive effect on chemical resistance of the applied coating to a building or transportation conveyance. Solvents and acidic aqueous solutions on coated surfaces have been evaluated by spot testing. No loss of film coating consistency was observed after one month of direct exposure to chemicals in a formal testing. (This is a fundamentally important performance criterion for assessing the barrier properties of a protective coating using Z 1074 resins.)

The unusually long durability and stain-release qualities, while maintaining surface thickness and coloration, make Z 1074 coating formulations ideal for commercial building exteriors and transportation vehicles. It has been successfully applied in actual customer applications on building substrates such as concrete, fiber-reinforced tiles, bricks, steel, aluminum and plastics, protecting all from permanent vandal attack via graffiti.

In Europe during 1998 and '99, paint formulated from Fluorobase Z has been successfully applied on the following.

• Trains and carriages of Italian National Railways.

• Inter-country and intra-country ferries for local transportation (150 small ferries and six large). Floating ferry slips have been also coated with Z 1074.

• Three train stations have been coated, with 11 stations specified.

• Two new buildings have been treated, one a large engineering structure, the other a 20-story residential building. Interest among building architects and developers is growing monthly.

Owners of the last two buildings requested as part of their pre-selection evaluation criteria a demanding 20-part test, conducted in two distinct phases. Anticipated building-coatings formulated with Z 1074 performed exceedingly well in all tests, as evidenced by the results in Table 3.

Conclusion

Owing to its unique chemical bonding properties and molecular structure, Z 1074 is easily formulated with common paint materials, such as pigments and fillers. Resulting paints can then be sprayed or brush applied on construction materials either at the factory or in the field, at job sites. Coatings formulated with Z 1074 dry in minutes at ambient temperatures and do not require costly, time-consuming heat curing. Within hours, solid anti-graffiti properties are developed.

Pre-existing anti-graffiti coating formulations developed in the past decade have been useful in helping remove graffiti from structural surfaces, but typically require much greater cleaning efforts to achieve success. They often sacrifice the coating that is under the graffiti during cleaning, mandating expensive and sometimes frequent recoating. As a result, too often the only option for the owner of a graffiti-damaged building or structure has been to simply hope the graffiti fades and becomes less noticeable after a few years. Coatings with Z 1074 are the first not to need recoating to eliminate graffiti.

The new generation of coatings that provide superior performance with Z 1074 resin in terms of durability and cleanability can be extended to most of the substrates the commercial building industry can access and use. An economic and effective solution to the damage of graffiti, using coatings with Fluorobase Z can be achieved with a small incremental investment. Once applied, it gives an immediate increase to the value of the panels coated because the appearance and performance is immediately appreciated and rewarded longterm.

Ausimont is a member of the Montedison Group, a world leader in fluoropolymer research and formulation.

For more information on fluoropolymer coating resins, contact Ausimont USA, 10 Leonard Lane, Thorofare, NJ 08086; phone 800/221.0553; in NJ, phone 856/853.8119; fax 856/384.6126; e-mail prodinfo@ausiusa.com; in Europe, contact Ausimont SpA, V.Ie Lombardia 20, I-20021 Bollate (Milano), Italy; phone 39/02.3835.6362; fax 39/02.3835.6538; e-mail angelo.locaspi@ausimont.com; visit www.ausiusa. com.

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