Self-Cleaning Additive for Paints and Coatings

Green building technologies are of great importance to provide large modern cities with the capability of environmental protection and sustainable development. It is highly desirable to develop a long-lasting, self-cleaning technology for outdoor paints and coatings to keep building surfaces clean.

Developed by a local research team, the proposed technology relates to an ultrasonic-assisted, wet chemical method to prepare doped titanium dioxide (TiO2) material as an additive for paints and coatings. This additive brought about the photocatalytic/photo-induced self-cleaning effect on the coating surface, enabling long lasting surface cleanliness thus less maintenance, as well as removal of organic air-borne pollutants such as sulphur dioxide (SO2) and nitrogen oxides (NOx) species through the photo-degradation reactions.

Unlike conventional TiO2-based additive which can only be activated by specific band gap of UV light (e.g., 3.2eV, 387 nm), the proposed doped TiO2 additive extends its active spectrum of photocatalytic activity into the visible light range. This greatly improve the self-cleaning effects and surface de-pollution efficiencies.

The research team has completed preliminary evaluation using a water-based paint with 1% doped TiO2 additive with one layer topcoat at a rooftop environment, through an 18-month test and obtained satisfactory results in terms of surface cleanliness and durability of the painted surface. The team is seeking partnerships with industry through R&D collaboration, consultancy or licensing of this technology.

This self-cleaning additive has the following features:

• 1-2% loading of the doped TiO2 additive
• Extended response of self-cleaning activity towards the visible light spectrum
• Compatible with water-based paints and coatings
• Paints and coatings incorporated with this self-cleaning additive can be easily applied on the surfaces by painting or spraying application methods
• Degrades particulate and organic air-borne pollutants to clean building surface
• Reduce the frequency of maintenance and the need to re-coat surface

This self-cleaning additive for paints and coatings can be used on the exterior and interior of buildings, glass panels and various surfaces for its self-cleaning effect to reduce the manpower, cost and time needed for cleaning and maintenance.

Multi-functional green building paint can be used on existing and new buildings. It is easy to apply, and less maintenance is required. The coated paint will be helpful to keep the building surfaces clean and degrade environmental pollutants.