Coatings and Tire Tracking – Tire Marks on Garage Floor Epoxy
Tire Tracking Causes and prevention — Tire Marks on Garage Floor Epoxy
You did everything right. You spent two days grinding your floor, 2 days coating it and kept everything out of your garage for a week. Less than a month later you have ugly tire marks on your epoxy floor. The problem is way more common than you think.
One of our suppliers share this with us and we are sharing it with you, “As Is”
As many of us are aware, tire tracking and what is commonly called paw printing has been an area of concern for both National Polymers and the industry for which we serve. Accordingly, we have spent time researching this phenomena to relay information concerning the cause and preventive measures that can be taken to minimize this problem. Perhaps the most judicious approach to this problem is the education of the customer.
Phase one of our investigation was directed toward the accumulation of information to uncover the causes of paw printing. In addition, this investigation coupled with input from rubber manufacturers, has provided enough information to hypothesize the cause for the tire tracking or paw printing.
First, in the manufacture of all tire rubber, an ingredient is used as an antioxidant-antiozonant. This chemical functions as a preservative that allows the tire to remain flexible, withstand the elements of the ozone and UV degradation and enjoy a long tread life. Chemicals such as diaryl-p-phenyenediamines and N-(1,3-dimethylbutyl)-N-‘-phenyl-p-phenylenediamine are commonly used. However, depending on the manufacturer, many derivatives of this type of chemical can also be used. The use of these chemicals is so common that the chemicals are referred to by codes such as 6PPD or IPPD, depending on the manufacturer. According to a recent conversation with a major tire manufacturing engineer, the tire manufacturers are fully aware of the problem of paw printing in the coating industry. Accordingly, many tire manufacturers have selected the least detrimental (to flooring) chemical in the manufacture of tires. However, many manufacturers are still using products such as the IPPD which is far more prone to discolor a coating than the 6PPD. Many chemical reasons exist that account for the paw printing, however, in layman terms, here is what information we have found.
Products such as the 6PPD are colorless when introduced into the tire formulation and do not by itself cause the paw printing to occur. However, the moment that the 6PPD becomes oxidized, it only take a few parts per million of the 6PPD to create the typical paw print on a coating. To further compound this problem, a high aromatic greenish brown oil commonly used in the manufacture of tires, continually leaches from the tire and can contribute to the exudation of the 6PPD from the rubber. Unfortunately, the 6PPD can be easily oxidized. Once the material is oxidized, it turns to a purple/gray/black color depending on the severity of the oxidation. This color variance in conjunction with the actual concentration of the 6PPD accounts for the differing types of paw printing from slight deglossing to actual color changes. In addition, it is quite
possible for atmospheric contaminants to cause sufficient oxidation to occur, resulting in a paw print. One reason that the 2K urethane system has shown such good promise in this type of application is the inability of the 6PPD to migrate into the coating. However, even surface contact in enough concentration results in surface paw printing. Subsequently, the longer the tire remains in contact with the area, the greater the chance that enough 6PPD will leach out of the tire and into the coating itself. Given enough time in one location, not only will enough 6PPD migrate out of the tire, but the constant exposure may result in the actual migration of the chemical into the coating creating a more pronounced and deeper stain.
Many other parameters play an important role in this phenomena such as pigment volume concentration and even the curing mechanism. To further illustrate this problem, suppose that the 2K system is placed at 40 degrees F. Further suppose that 1% of the solvent does not evaporate before the reaction process causes the material to gel and form the coating on the floor. Finally, let us further presume that the solvent that was entrapped in the curing process later volatizes with the passage of time. This will create a void wherein the passage of the 6PPD will enjoy a greater probability of migration. Many such scenarios can account for many variances from job location to location as well as variances on the same job sight. In addition, this would also account for the problem being compounded by exposure to a tire surface before a full cure is achieved. If the product is 95% cured after two days, and this is a likely projection, but continues to cure for the next several days, then the window of penetration is at its greatest when the coating is new and not fully cross linked. Add in all the other variances such as the age of the tire, manufacture of the tire, temperature of the floor, atmospheric contaminants, color of the coating, length of cure, migration rate for each type of tire, specific chemicals used for each tire, weight of the vehicle, UV exposure, relative humidity, temperature of the tire and so forth and so forth for endless possibilities.
The truth of the matter is, with the exception of some colors, our coatings do not discolor. The chemicals that migrate out of the tires and then oxidizes, discolor and cause the coating to look discolored. However, until a better solution is available from the tire manufacturers, which many of them have seemed to address by the selection process for the antioxidants, the coating industry will be plagued by this problem.
Unfortunately, this is a problem that we cannot presently cure any easier than the tire industry can make tires without the use of these chemicals. However, in the interim, it is best advised to educate the customer as to the cause for this problem. First, any customer with this potential for a problem should be educated as to the cause of the problem. Next, this education process should detail the importance of allowing the coating to fully cure before exposure to tires and the chemicals that can potentially migrate. Finally, because we know the problem is random and we are unable to prevent these occasions, it would be advisable for the industry to park the vehicles on mats, corporate logo carpets or any suitable material to prevent at least long term contact to the coating. In this case, a least right now, prevention is the only cure.