additives feature | Titanium dioxide
Performance Chemicals segment, including the TiO2 business, is expected to complete its spin-off from DuPont by mid-2015, but innovation and new product development continues, notes Niedenzu. Multi-functional TiO2
catalytic) is important. TiO2 can provide an additional
protection against photochemical degradation of the polymer because TiO2
possesses an intrinsic UV blocking function. However, TiO2 grades that provide more than
opacity, brightness, and tint strength will continue to be a trend in the coming years, agrees William Lashway, principal engineer for plastics at Cristal. “TiO2
brings a
UV absorbing capability used with durable grades, but there may be more options possible. Also the heat management aspects of TiO2
are finding a strong fit in
the current market and will continue to grow and expand,” he notes. In addition, Cristal is developing a next-generation high-performance masterbatch grade and continues to work on extending durability.
Coatings for specific applications At AMI’s Thermoplastic Concentrates conference in January 2014, Richard Bordeleau, technical support
manager at Huntsman Pigments, explained that TiO2 particles can be coated with various types of inorganic coating and with an organic treatment to improve properties such as dispersibility and durability (see box story). To select the best pigment for an application, he
noted, it is important to know whether an application will have outdoor exposure and what level of durability will be required. In addition, identifying the dominant mechanism of degradation (photochemical or photo-
New investments
Huntsman recently completed an update of its TiO2 manufacturing facility in Scarlino, Italy. The new iron-sulphate plant built there will allow the company to use a wider range of feedstock to produce its TiOxide pigment and its Altiris pigment, reduce the generation of
gypsum (a co-product), and convert spent acid from TiO2 pigment manufacturing into iron sulphate products for the water treatment, animal feed and cement markets. The plant was completed on 1 July. Last summer, the company’s TiO2
manufacturing
facility at Greatham in the northeast of England received three Chemical Industry awards: the ABB Manufacturing & Resource Efficiency Award, the Environmental Leadership Award and (as a joint winner) the Company of the Year Award. This year Huntsman
celebrated 80 years since the production of its first TiO2 pigment manufactured at its Billingham facility in the
Types of surface treatments for particles
Speaking at AMI’s Thermoplastic Concen- trates conference in January 2014, Huntsman’s pigments division’s Richard Bordeleau explained the types of
treatments that can be applied to TiO2 pigments. Inorganic coatings (about 1-15% by
weight), include oxides of silica, alumina, zirconia, and phosphate, and hydrous TiO2
. Alumina improves dispersibility and
aids dispersion stability, but provides minimal durability increase. Fluffy silica improves dispersibility and significantly increases opacity in high PVC systems. Dense silica improves dispersibility and significantly increases durability. Zirconia significantly increases durability. Phosphate, added prior to wet milling, improves dispersibility.
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In addition, organic treatments can be added, typically at less than 1%. Polyols aid milling during TiO2
production and
improve dispersibility. Silicone deriva- tives create a hydrophobic surface. Other patented organic treatments (such as silanes and phosphonated organics)
PIPE & PROFILE EXTRUSION | January/February 2015
improve compatibility with resins and can act as a lubricant to improve processability. Huntsman offers a range of titanium
dioxide pigments with various combina- tions of inorganic and organic treatments. ❙
www.huntsman.com
www.pipeandprofile.com particles can also be a
cause of photocatalytic degradation, because of their strong interaction with UV light. It is therefore important to select the right product based on its inorganic surface treatment. Dense silica and zirconia treated pigments are generally preferred to counteract photocatalytic degradation, explained Bordeleau.
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