Marrying Durability And Environmental Preferability
By Theodore Tysak Ph.D.
MAY 04, 2012
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Finishes based on the newer polymers can be applied in marginal application conditions without encountering the same recoat issues that may be present with conventional coatings.
In addition to gloss retention characteristics and tolerance to marginal application conditions, the newer polymers based on multiple crosslinking technologies incorporated into single polymer matrices furnish low odor, an excellent balance of detergent resistance and removability and respond to all types of maintenance conditions.
Formulations based on these polymers combine low volatile organic compound (VOC) content with other desirable environmental benefits to produce important performance properties, including high gloss, resistance to harsh cleaners, excellent removability and, most importantly, durability.
The polymeric vehicles employed in floor finish coatings must provide a remarkably diverse set of performance properties.
The list of these expected attributes includes an attractive appearance, protective durability, water and detergent resistance and ease of removability.
However, these properties represent only a starting point.
The formulation that will be used to coat floors demands other features from the coating vehicle.
Floor polishes are applied in some instances to a vinyl-based substrate that is categorized as being resilient.
Consequently, the vehicle must supply flexibility and adhesion so the coating will not be damaged when the floor is exposed to normal pedestrian traffic and floor maintenance.
The polymer must also impart significant measures of aqueous resistance and toughness so the coating can endure repeated cleanings and other assaults that normally occur during the life of the coating.
Over the last several decades, waterborne acrylic polymers based on zinc-crosslinked acrylic emulsions have made significant inroads in floor care coating markets.
Offering exceptional recoat characteristics, resistance to marring, scuffing and black heel marking, zinc-crosslinked acrylic-based emulsion polymers have been employed successfully to meet the varied needs of the floor care market.
With the advent of "green cleaning" and eco-labeling becoming more prevalent in the building maintenance industry, zinc containing acrylic-based polymers used in floor polishes may not be the vehicles of choice.
Despite the growing need for environmentally preferred floor finishes, custodians and maintenance crews who apply finish to flooring substrates generally elected not to use "green" formulations.
The reluctance of professional maintenance personnel to use environmentally preferred formulations may have been due to the perceived or actual experience the building maintenance crews had of the "green" formulations not performing to the level expected.
The traditional waterborne acrylic zinc-free vehicles that have been in the market for many years provided a reasonable level of gloss and recoat characteristics, but they lacked the gloss retention properties of the zinc cross-linking counterparts.
Recently, the situation has changed dramatically with the introduction of unique acrylic-based vehicles that can meet the demanding needs of environmental responsibility and provide performance.
The fruit of new and innovative approaches to polymer design and the use of multiple crosslinking technologies within the same polymer network, these vehicles enable manufacturers to produce aqueous acrylic-based floor finish compositions with a much higher level of gloss retention than ever before for zinc-free finish compositions.
As a result, floor finish manufacturers can provide custodians and building care specialists with the advantages of current zinc-crosslinking finishes as well as maintaining low VOC capability and meeting environmental standards.
Achieving Gloss Retention
The key differences between the newer polymers and other waterborne zinc-free floor finish vehicles lie in the new products'' superior film formation properties.
The unique polymer composition and crosslinking technologies allow finishes based on the newer technologies to release water and coalescent more rapidly than coatings formulated from conventional zinc-free polymers.
As a result, films formed from the newer chemistries develop properties more rapidly than films based on conventional zinc-free coatings and, consequently, reach ultimate film integrity properties very quickly.
The ease and speed of the film formation process are critical to the appearance of floor finishes.
Conventional zinc and zinc-free polymers employed as vehicles in floor finish compositions are typically made extremely hard — a minimum film formation temperature greater than 50 degrees Celsius — for resistance to marring and scuffing.
They require high levels of coalescing and plasticizing solvents for film formation, and in the case of traditional zinc-free vehicles, they release the coalescent slowly.
On older floors based on vinyl composite materials, the flooring substrate may generally be porous to some degree and, consequently, tends to absorb some of the solvent.
If the flooring substrate soaks up enough solvent, the film may not form properly.
Instead of forming a continuous film, the coating may have irregularities where it interfaces with the substrate.
In some instances, these voids may produce an opaque haze that blurs the surface of the underlying floor and gives it a whitish appearance.
Floor finishes based on the newer zinc-free vehicles do not suffer from this problem.
These formulations form much better films — more continuous and uniform — under conditions that would cause film deficiencies with some conventional zinc and zinc-free technologies.
The exceptional integrity of the films manifests in outstanding appearance properties when conditions are not optimal for coating, such as when variations in humidity and temperature occur.
Floor polishes formulated with the new polymers match or exceed the standards of leading commercial formulations in this respect better than any previous zinc-free waterborne coatings designed for the floor care market.
Waterborne Floor Finish Vehicles
Of course, appearance properties such as gloss, clarity and defect-free appearance are not the only features required in a floor finish; formulations should be resistant to detergents.
They should also be able to tolerate exposure to water and aqueous cleaning products without deteriorating.
They should not develop soil impregnation issues when exposed to repeated treatments with detergent cleaners during maintenance operations.
And, finally, they should withstand repeated burnishing operations and be removable without damaging the underlying substrate.
The latest products that have recently been introduced into the marketplace provide these features as well.
However, in addition, to furnishing the properties expected of today''s floor finish vehicles, the newer polymers do it without the reliance of zinc as the crosslinking technology.
Long-term gloss retention is another benefit of superior film integrity properties.
Because films derived from the newer emulsions develop film integrity properties rapidly, the time needed for finishes based on them to develop ultimate film properties is essentially the same as with conventional finishes based on zinc-crosslinking chemistries.
As a result, floor finishes based on these recent polymers can be coated on floors and opened to traffic in a similar timeframe as expected with conventional finishes.
The exceptional gloss retention properties of formulations based on these newer emulsions derive mainly from their unique crosslinking and polymer chemistries.
Their unique polymer designs make them much more resistant to film damage that typically would result from maintenance operations as compared to older zinc-free chemistries present in the marketplace.
Their unique polymer design makes them more resistant to film damage than their hardness would imply.
As a result, films based on the newer polymers and exposed to maintenance operations — repeated exposure to disinfectant detergents and abrasive repair via cleaning and burnishing — will not soften the polymeric film and leave soils that typically detract from the appearance of the floor.
Conventional waterborne zinc-free coatings simply do not have this capability.
As far as performance features are concerned, the coatings are flexible and adhere well to typical resilient flooring substrates such vinyl, vinyl composition tile (VCT) and linoleum.
Maintenance contractors and floor care experts will also be drawn by the fact that these waterborne finishes can be stored for extended periods without stability problems.
Dr. Theodore Tysak is a technology manager for the floor and surface care business at the Dow Chemical Company. For more information concerning this article, Tysak may be reached at TTysak@Dow.com.
Dr. Theodore Tysak is a technology manager for the floor and surface care business at The Dow Chemical Company. For more information concerning this article, Tysak may be reached at TTysak@Dow.com.