Titanium Dioxide


For background information on what Titanium Dioxide is, and what it is used for, please scroll down.

The current situation with the Review of Titanium Dioxide by the European Chemicals Agency (ECHA) concerns all paint manufacturers worldwide, so the World Coatings Council has made up a statement to reflect the concerns of all the member Associations, and this follows.


Titanium Dioxide in Paint

Titanium dioxide (TiO2), almost universally used as a white pigment incorporated into paint and a variety of other products, is under review by the European Chemicals Agency (ECHA). At present, ECHA’s Risk Assessment Committee (RAC) has indicated that, in its opinion, “the available scientific evidence meets the criteria to classify titanium dioxide as a substance suspected of causing cancer (Category 2) through the inhalation route” under the EU’s CLP (Classification, Labelling and Packaging) Regulation. The CLP process is an ongoing regulatory program to harmonize classifications of substances based on hazard properties (but does not consider risk of human exposure). Classifications have implications across the EU for product labels, formulation restrictions and worker protection.

As part of this process, Europe’s RAC issues an advisory opinion to the European Commission. While that opinion is likely to receive wide attention, the detailed rationale for the opinion will only be released in a few months. The European Commission will then consider the matter for final approval as the hazard classification under the CLP. While the Commission usually adopts the RAC’s recommendation, there is considerable concern that the basis for the initial proposal is flawed and certainly does not inform on risk to humans.

It is important to consider that any risks profiled in the scientific evidence are attributable to dust (inhalation) exposures, and not to exposures from formulated products, like paint, where the dust is embedded in the mixture and not available for exposure. The World Coatings Council and its members provided the ECHA RAC with published studies and technical information of the industry’s longstanding safe use of TiO2 in paint, including good manufacturing practices and numerous exposure assessments showing that TiO2 , and for that matter all insoluble, inert (particulate) raw materials used in the (particulate) dust form, are unavailable for exposure during surface preparation on, or application of, the finished paint.

The World Coatings Council continues to monitor this process and has offered detailed published references on the inherent safe use of titanium dioxide in paints. In addition, the council supports the position of the Titanium Dioxide Manufacturers Association (TDMA, see https://www.tdma.info/) which is heading the effort to advance sound science on the classification issue, working in concert with many user industries to ensure responsible use.


BACKGROUND

The following information is summarised from the www.tdma.info website. For the full information, please click here.

Where does it come from and why do we need it?
Titanium dioxide (TiO2) is a bright white substance used primarily as a vivid colourant in a wide array of common products. It also has a number of lesser-known qualities that make it an extremely useful and important ingredient in our battle to fight climate change and prevent skin cancer.

  • Prized for its ultra-white colour, ability to scatter light and UV-resistance, TiO2 is a popular ingredient, appearing in hundreds of products we see and use every day, bringing significant benefits to our economy and overall quality of life.
  • Applications for TiO2 include paints, plastics, paper, pharmaceuticals, sunscreen and food.
  • As a photocatalyst, titanium dioxide can be added to paints, cements, windows and tiles in order to decompose environmental pollutants.
  • As a white pigment, TiO2 is one of the most important raw materials for paints and coatings.

What is titanium dioxide?
Titanium dioxide is a white inorganic compound, which has been used for around 100 years in a vast number of diverse products. It is depended on it for its non-toxic, non-reactive and luminous properties, which safely heighten the whiteness and brightness of many materials.
It is the whitest and brightest of known pigments, with reflective qualities; it can also both scatter and absorb UV rays.

What is titanium dioxide used for?
Its ultra-white colour, highly-refractive and UV-resistant properties make TiO2 enormously popular with both the industrial and consumer sectors, appearing in dozens of products that people use and see daily.

Beyond paints, catalytic coatings, plastics, paper, pharmaceuticals and sunscreen, some lesser-known applications include packaging, commercial printing inks, other cosmetics, toothpaste, and food (food colourant E171).

Paints, coatings and plastics
When explicitly used as a pigment in paints, TiO2 is called titanium white, Pigment White 6 or CI 77891. It is also known as ‘the perfect white’ or ‘the whitest white’ due to its powerful, pure whitening qualities.

Until laws changed in the 1920s, most commercial paint manufacturers used highly toxic white lead as a whitener and did not initially convert to using titanium dioxide, partly due to its higher cost. Zinc oxide (ZnO) is also used as a white pigment but is not as effective.

Titanium dioxide is now one of the most common pigments in global use and is the basis for most paint colours. It is also found in coatings and plastics. These uses of titanium dioxide account for more than 50 per cent of its global usage.

Its high refractive index means that, as a pigment, it is able to scatter visible light. This results in an opaque colour and creates a bright, reflective quality when applied to a surface or incorporated into a product.

A key example of its use in these applications is as a coating for wind turbines, providing both a suitable white colour and protection from UV degradation.

Environmental benefits
Due to its various properties, titanium dioxide has been found to be useful for many different environmentally-friendly applications.
  • When used in a paint coating on the outside of buildings in warm and tropical climates, the white, light-reflecting qualities of TiO2 can lead to considerable energy savings, as it reduces the need for air-conditioning.
  • Also, its opaqueness means it doesn’t need to be applied in thick or double coats, improving resource efficiency and avoiding waste.
  • As a photocatalyst, titanium dioxide can be added to paints, cements, windows and tiles in order to decompose environmental pollutants.

What are the physical properties of titanium dioxide?
Titanium dioxide has a number of unique characteristics that make it ideally suited to many different applications.

It has an extremely high melting point of 1,843ºC and boiling point of 2,972ºC, so occurs naturally as a solid, and, even in its particle form, it is insoluble in water. TiO2 is also an insulator.

Unlike other white materials that may appear slightly yellow in light, because of the way TiO2 absorbs UV light, it doesn’t have this appearance and appears as pure white.

Importantly, titanium dioxide also has a very high refractive index (its ability to scatter light), even higher than diamond. This makes it an incredibly bright substance and an ideal material for aesthetic design use.

Another crucial property of titanium dioxide is that it can show photocatalytic activity under UV light. This makes it effective for environmental purification, for different kinds of protective coatings, sterilisation and anti-fogging surfaces, and even in cancer therapy.
  • Brilliant
    Brilliance, colour strength, opacity and pearlescence unlike any other substances.
  • Resistant
    Stability to heat, light and weathering prevents degradation of paint, in films and embrittlement of plastics.
  • Protective
    Ability to scatter and absorb UV radiation makes TiO2 a crucial ingredient for sunscreen, protecting the skin from harmful, cancer-causing UV rays.
  • Non-toxic
    Being non-toxic and non-reactive it can be used in food and pharmaceuticals without affecting other ingredients.
  • Powerful
    Is used as a photocatalyst in solar panels as well as reducing pollutants in the air.

What are the forms of titanium dioxide?
TiO2 possesses different qualities depending on whether it is produced as pigment-grade or nanomaterial-grade. Both forms are tasteless, odourless and insoluble.

Pigment-grade TiO2 particles are approximately 200-350nm in dimension and this form accounts for 98 percent of total production. It is used mainly for light scattering and surface opacity applications, such as paint – this includes its use as a base for various colour paints or as a standalone ‘brilliant’ white.

Nano, or ultrafine TiO2 comprises of primary particles sized less than 100nm. In this grade, titanium dioxide is transparent (colourless) and boasts improved UV scattering and absorbing properties compared with larger particle-size, pigment-grade TiO2.

What is titanium dioxide made of?
Titanium is one of the most common metals on earth, but it does not occur naturally in this elemental form. Titanium dioxide – also known as titanium (IV) oxide or titania – is the naturally occurring compound created when titanium reacts with the oxygen in the air. As an oxide, titanium is found in minerals in the earth’s crust. It also found with other elements, including calcium and iron.

Its chemical formula is TiO2, which means it consists of one titanium atom and two oxygen atoms (hence dioxide). It has a CAS (Chemical Abstracts Service) registration number of 13463-67.

TiO2 is typically thought of as being chemically inert, meaning it doesn’t react with other chemicals and is, therefore, a stable substance that can be used in many different industries and for a variety of applications.

The future of titanium dioxide
For a substance that is relatively unknown to the public, it’s amazing how many everyday products titanium dioxide can be found in.

Because of its many varied properties, our skin, cities, cars, homes, food and environment are made brighter, safer, more resilient and cleaner by titanium dioxide. With a legacy of 100 years of safe commercial use, titanium dioxide is only going to become more vital as our environment faces greater challenges from a growing population.

 
 
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