For the past several decades, the focus of interior latex paint performance has been on improved hiding power, scrub resistance and color acceptance properties. Driven by regulatory initiatives, new paint formulations are required to meet low-VOC regulations. These regulations have forced paint formulators to seek practical solutions to overcome additional challenges, such as poor wetting, flow, foaming, block resistance and stain resistance that result from the reduction in VOC content in paints. For flat to low-sheen eggshell paints, washability (or easy-clean) has become the most difficult property to achieve. Softer resins, lack of coalescent aids, longer film forming time, lower film forming temperatures, and overuse of surfactants and additives are contributing factors to poor washability. Easy-clean and stain resistance are not only highly desired by consumers, but these properties can also extend paint service life and reduce recoat cycles for environmental protection. These benefits provide long-term value to our society and future generations.
Stains that adhere to interior latex paint films are divided into two groups: hydrophilic and hydrophobic. Hydrophilic stains, often called common household stains, include soy sauce, tea, coffee, red wine, colored markers, etc. Hydrophobic stains mainly come from oily hands or fingerprints typically found around door frames and light switches. Other hydrophobic stains are crayons, pencils, or tomato sauce.