The role of titanium dioxide (TiO2) and other white pigment technologies is essential in achieving exterior performance and improving a coating's opacity. As the market for long-lasting products continues to grow, so does the importance of selecting the right grade of TiO2.
"TiO2 plays a complex role in paint durability," said Carlos Verdejo, global offerings manager, coatings, DuPont Titanium Technologies. "TiO2 itself is extremely durable, but the organic resin of the paint is not. One of the greatest threats to organic resin is UV light, which has enough energy to break chemical bonds in the resin polymer."
According to Verdejo, the primary role of TiO2 in most paints is beneficial, absorbing virtually all of the UV light that it encounters and protecting the underlying resin in the process. However, he pointed out that TiO2 is a photocatalyst, and some of the UV light energy is transformed into reactive chemical energy in the form of chemical radicals. "The best pigment is one that maximizes binder protections and minimizes photocatalytic activity," he added. "This is done by improving pigment dispersion in the final paint film and decreasing photocatalytic activity."
Kelly Green, vice president of market management, Tronox Inc., said durable grades of TiO2 assist in maintaining the integrity of exterior coatings and plastics by ensuring that the the TiO2 does not directly contribute to the degradation of the film and by shielding the interior portions of coatings or plastic from penetrating UV light.
"Coatings or plastic formulated with durable grades of TiO2 will have reduced levels of chalking and will have a better resistance to fading and gloss loss," said Green. "Today's durable grades of TiO2 provide outstanding combinations of durability and optical properties that enhance the paint formulator's tool kit by providing more choices and options to achieve their goals for their exterior paints."
Consumers and contractors have high expectations for their paint in terms of performance, coverage and appearance. TiO2 manufacturers work hard to meet these needs by developing new grades of TiO2.
"New grades are continually being designed to provide greater value to the coatings manufacturer and the coatings consumer," said Verdejo. "We are constantly gathering 'voice of the customer' data so that we can react quickly to market needs."
As a result of this customer feedback, DuPont recently made some enhancements to some of its older TiO2 grades. "Customers like the end-use performance of the original grade, but wanted it to be easier to disperse," said Verdejo. "The result is a grade that retains its original paint performance but allows the coatings producer to cut back on the amount of time and energy required to make the paint."
DuPont Titanium Technologies has recently launched two new products into the coatings market. TD-6200 is designed as a multi-purpose grade with excellent dispersibility and durability. R902+ is an improved version of its R-902. The new product features increased dispersibility while retaining all other performance attributes.
According to Green, TiO2 provides the opacity or hiding power in nearly all paints. "Today's generation of TiO2 pigments do this with even better performance than ever before," he added. "Pigment manufacturers have developed products that provide greater opacity at lower loading levels giving even better performance, with less TiO2 than was previously required. This means that manufacturers have more flexibility in their formulations, which allows them to develop even more new effects in their coatings."
Tronox introduced a new dry hide grade in 2005 that now is commercially available. "We are working one-on-one with customers to formulate their products to use the new grade for architectural paints and anticipate increasing sales throughout this year," said Green. "We have new and improved products in the pipeline for nearly every major application and these grades are in various stages of development, from concept to laboratory development and preliminary plant trials."
Facing Rising Prices
Because of rising prices for titanium dioxide, coatings companies may look into using extender pigments to reduce overall costs. Titanium dioxide suppliers Coatings World spoke with cautioned that these cost cutting measures are not always worth it. Many times, especially where quality is concerned, you get what you pay for.
"It is fairly common practice for companies to use fillers of various types in an attempt to reduce TiO2 use and decrease their cost," said Green. "Use of these extenders, which include calcined clay, fine particle size CaCO3 and opaque polymer (polymer microvoid technology), can have a very negative impact on other performance properties important to the end-use paint customer, such as touch-up, wet hiding, stain resistance and scrub resistance."
Tronox works directly with customers to optimize their paint formulations to get the best possible performance from the TiO2 with minimal impact on other key performance properties, according to Green. "By getting the best possible performance from your TiO2, you can maintain the best overall combination of properties in the paint at a reasonable cost," he said. "For example, a slight change in dispersant level, dispersant type or other ingredients can significantly enhance the performance and efficiency of the TiO2, and thus eliminate the need to use lower-cost, lower-performance fillers."
"We believe all coatings markets should be using TiO2 as efficiently as possible, since no one benefits in the long term from waste due to inefficiency," said Verdejo. "That said, there are cases where coatings products are falling short of their hiding power potential. Sometimes reformulation is needed, particularly with respect to keeping the TiO2 particles well dispersed during pigment drying, when the liquid environment is changing rapidly and drastically. The key here is to alter the dispersant and other additives to create a robust dispersion."
In some cases, changing pigment grades can improve performance. New pigment grades are formulated to take maximum advantage of the chemistry of new dispersants and additives, according to Verdejo. "One area where I recommend caution is the notion that the use of certain extenders can greatly reduce the amount of TiO2 needed in a paint," he said. "Every few years we hear this claim from different extender manufacturers. It could well be that some cost improvement can be gained by partially substituting a modest amount of pigment with extender, but improvements at the levels suggested can only occur if the pigment is being used at a very low efficiency to begin with. We simply do not believe that this is the case for the vast majority of the coatings being made toady."
Maintaining open lines of communication to help their customers understand its role and select the best possible TiO2 pigment is key.
"We have dedicated teams of sales, customer service and technical experts located around the world so we can assist customers where they operate," said Green. "Our customer service includes technical support, formulation optimization, product assistance, problem-solving, weathering facilities, process efficiency and other value-added joint projects. In addition, our research and development teams work closely with customers to enhance existing grades and develop new, high-performance pigment grades that meet customers' increasingly stringent technical requirements and address future needs."
"We always welcome interactions with customers," said Verdejo. "This is an essential way for us to anticipate needs in the industry and respond in a timely fashion. We do this through customer/marketing interactions, as well as those at a more technical level. We really learn a lot through these contacts, and our customers benefit as well."
Developing and growing their business in the Asia-Pacific region is also an important priority.
"The Asia-Pacific region is a key strategic growth area for Tronox," said Green. "This region is experiencing strong growth in excess of six percent and is projected to be the largest market for TiO2 within the next three to five years."
Tronox has a major presence in the region, supported by its operation located in Western Australia. This facility currently supplies the majority of its annual production to customers throughout the Pacific Rim. In addition, the company is increasing its sales and technical support services in the area.
"We project a strong demand for TiO2 as the Chinese economy grows," said Verdejo. "We currently serve Asia with our plant in Taiwan, and are in the early stages of building a world class plant in Dong Ying, in the PRC. This allows us to increase our supply of locally produced material in Asia and to position ourselves to grow with China."
BASF Offers Functional Black Pigments for Solar Heat Management
BASF has recently launched new NIR-transparent black pigments to reduce surface heat on construction elements. Lumogen Black FK 4280 and Lumogen Black FK 4281 functional black pigments have been designed to reduce the solar heat buildup of dark colored construction elements. According to the company, the solar heat buildup of dark colored, and even black construction elements can be cut in half when using NIR-transparent black pigments. BASF's newly developed functional black pigments offer exceptional transparency in the range of solar infrared radiation from 750 nm up to 2,500 nm. In addition, Lumogen black pigments offer excellent heat resistance, color strength and migration stability, as well as extreme resistance to chemical and physical effects, good dispersibility and insolubility in all common solvent.
Aside from solar heat management in construction, the coatings and printing ink industries are other potential applications for these cool black pigments.