Understanding the Performance of Fluorochemical Protectors on Wool Fibers
The issue is repeatedly raised at carpet cleaning industry meetings about the effectiveness of carpet protectors on wool, Oriental-style rugs and carpeting. To my knowledge, prior to this study, no specific technical data was available on this subject. In an effort to begin to gather factual technical information on this subject, the National Institute of Rug Cleaning, a division of ASCR International, requested specific research be conducted and a report given at the annual ASCR convention in March 2000. Experiments were designed to evaluate the re-soiling, repellence and stain resistance of fluorochemicals applied to wool products. This was a cooperative effort between the DuPont company, a leading manufacturer of Protectors, Atiyeh Bros., Inc., nationally recognized specialists in the care of Oriental and domestic wool carpeting, and T. Hill & Associates, technical consultants to the carpet and cleaning industry.
The experiments were designed to evaluate several different types of fluorochemical repellent systems, the effect of drying with and without heat and drying vertically versus flat. Fluorochemical repellent systems evaluated included after-market repellent carpet systems, textile-type repellent systems and carpet protector with stain blockers.
Oriental-style wool carpeting was purchased through Atiyeh Bros. for this experiment. This particular carpet type was selected because it had large, white areas that could be used to determine stain and re-soiling performance. The carpet was Karastan style 738, Axminster woven through the back, New Zealand skein-dyed wool. The carpeting was cut into 12" x 24" pieces and then washed and rinsed at Atiyeh Bros. The washing and rinsing incorporated their normal procedures for rug cleaning. After the rinsing step, the carpets were either treated wet or dried and then treated the following day. The treatment consisted of spraying the carpet sample with the desired repellent followed by brushing to level the application. The spray equipment was the typical “garden-type sprayer” used in the after market. Table 1 outlines the repellent choices and drying conditions. Our targeted application rate was 500 to 800 ppm fluorine on weight of carpet.
Once all of the samples were treated and dried, they were shipped to the DuPont Technical Laboratory, Chambers Works, for testing. The first test that was performed was fluorine analysis on fiber samples from samples dried vertically. Since all of the treatments contained fluorine, this analysis would determine: If the sample was treated and the amount of the treatment; If water migration occurred, did it cause a treatment concentration gradient.
Fluorine analysis indicated that the samples were, in fact, treated; however, there was no clear evidence of treatment migration. Fluorine analyses indicate variability between top and bottom samples, but it was random. Sometimes the top was high in fluorine and the bottom low and vice-versa. The difference was probably due to uneven spray application versus migration. It is the author’s opinion that the carpet sample size was too small and dried too quickly to show migration. The data is insufficient to conclude that migration does not occur. This is based on the observation that samples measuring 9' x 12' dried vertically in the same area had water dripping from the bottom of the carpet.
Additional samples measuring 12" x 6" were evaluated for each treatment and for each drying condition for drum soiling. We used AATCC dry-soil described in AATCC Test Method 123-1988, and placed the samples, soil and plastic beads from the original 24" x 12" sample in a rotating drum. After 15 minutes of rotation, the samples were removed, vacuumed and light reflectance was measured. The re-soiling is reported as Delta E, the difference between the original sample and soiled sample. The lower the Delta E, the better the performance.
Based on the drum soiling data, the following conclusions are possible:
A. The cationic carpet protector and the carpet protector plus blocker provide the lowest soiling and performance is improved with ambient drying.
B. The textile repellents contribute to soiling regardless of drying conditions.
It probably is not surprising that the textile repellents contribute to soiling. Because the fluoro polymers used in these systems were designed to provide dynamic repellence with high temperature cure. These products are normally softer polymers, thereby possibly trapping soil, whereas harder carpet polymers tend to repel soils. These after-market carpet products with harder polymers are designed for low soiling with ambient cure.
Water RepellenceAll the samples were tested for water repellence using the DuPont water test kit. The carpet protector containing blocker was the only treated sample that did not have repellence. This is not surprising since the “blocker” used for this application was hydrophilic. The two samples that provided the best performances were the Cationic Carpet Protector and the Anionic Carpet Protector A.
Stain ResistanceStain resistance was evaluated using a 24-hour Kool-Aid test. The procedure involved exposing a four-inch diameter circular area of the carpet to 100 ml of cherry Kool-Aid™ for 24 hours. After 24 hours, the carpet was then rinsed with water and dried. The rating scale was one to five, five representing no staining, and one representing severe staining.
The data indicates that we can improve stain resistance by one to two units. The highest water repellent chemical, the “Cationic-Carpet Protector” had the highest rating. We attribute this improvement primarily to improved repellence. The higher repellency achieved with the cationic material prevented wetting with the aqueous Kool-Aid™ solution.
Floor TraffickingThe last part of our testing was to evaluate the treated carpets with actual foot traffic. This was accomplished by placing samples from each of the treatments and drying conditions at a school in New York. We used three samples and placed them randomly throughout the walk area. We normally use three samples to obtain more accurate data, and on occasion, individual samples are destroyed. The samples are vacuumed daily and reflectance (Delta E) is measured at various trafficking intervals.
Based on the floor traffic data, we were able to draw the following conclusions: The two best products in this test for low soiling up to 23M trafficking was the cationic carpet protector and the anionic carpet protector with blocker; The two products mentioned above, also seemed to perform best with second day application onto dry carpet followed by ambient cure; Somewhere between 23M and 46M the performance equalized, indicating that the best treatments provide good early dry-soil repellence.
We compared the Drum Soiling Versus the Floor Soiling@23M Trafficking. This comparison indicates that the drum soiling was a good predictor of floor trafficking. The two products that performed best in drum soiling also performed best on actual floor trafficking. The drum soiling, however, is not a prediction of durability.
ConclusionsAlthough this test was limited to one style of Oriental wool carpet, the test was successful in demonstrating a laboratory technique of drum soiling, which predicts early floor trafficking. Two products were also identified that provided early low soiling rates. These two products can be included in further studies of additional carpet styles.
Many of the Oriental wool carpet styles are dark in color and have good soil hiding properties. With these styles, dry-soil protection may not be as important as repellency. In our test, we identified a cationic product that had high water repellency. This product would provide protection against aqueous stains by its repellent nature in addition to dry soiling. However, should repellency not be desired, carpet protectors with blockers can be considered.
Commercial cleaning at facilities with similar conditions and equipment to Atiyeh Bros. would indicate that the preferred application of soil and stain retardant products is following drying of the cleaned carpet. Treating carpet immediately following washing and then drying with heat appeared in our test to have poorer performance. There are several possible explanations for this unexpected result, but at this time, we do not have data to support any conclusion. However, application to dried carpet with ambient cure is a practical application technique.
Further testing will be required to determine if the carpets can be treated and dried vertically. However, since the preferred application is on dried carpet, this may only be an issue with very large carpets. This is an easy test to run during a commercial trial.
While our tests indicated that some product formulations proved more durable than others under actual foot traffic, the need for more testing is indicated to pinpoint this durability question to get optimal performance. The need for specific products for wool fibers was supported by these experiments. Correlation between these and other durability tests and residential use equivalents would help answer questions about the recommended frequency of application of protectors.
It is our hope that these experiments will lead to more study and eventually even to the eventual development of fluorochemical carpet protectors specially formulated for wool products.