Special effect pigments remain highly sought after within Asia’s coatings sectors, where ultramarine’s natural transparency offers many possibilities for designers. Its unique position within the colour space means that no other pigment or combination of pigments gives such a chromatic, red-blue shade that works in synergy with interference pigments. Here, Holliday Pigments’ Managing Director, Glyn Jagger, discusses the proven properties that have helped establish its Ultramarine TR grade as the pigment of choice for a wide variety of coatings applications.
“In volume terms, Asia is probably the largest consumer of technical ultramarines in the world,” says Glyn.
“Despite increasing competition from domestic suppliers and volatile market conditions we have managed to maintain impressive sales across the region. Our strength of position prevails from the technical properties and proven performance of our ultramarines. Where domestic suppliers tend to compete on price - adopting the strategy of producing lower quality products at lesser cost - our grades appeal to a more discerning customer looking for a high quality product that will guarantee the best and safest performance for a particular application.
“That’s why we invest so much time and resource into re-evaluating our existing pigment grades. The following piece of research was conducted by a former colleague but clearly demonstrates Ultramarine TR’s superiority and is indicative of the type of ongoing investigation that we’ve always done and will now be doing more of with the backing of our new parent company, Rockwood.”
Back to Black
The development of innovative effect pigments such as the Merck Colorstream range allowed for a new range of stylings in coatings to be achieved. The Colorstream range belongs to the group of angle-dependant effect pigments – commonly referred to as the ‘colour flop’ pigments. These consist of silica platelets coated with high refractive index metal oxides such as TiO2 and Fe2O3. These flakes act as both a true optical layer and a transparent substrate without a masstone colour. Therefore, the way that light interacts with both these pigments and any other components in the coating system is critical. The addition of even small amounts of white TiO2 will lose impact, as the light scattering caused by the white pigment interferes with the light interacting with the effect pigment. Alternatively, the addition of a small quantity of carbon black will give an enhanced effect, as the black provides a ‘backing’ for the effect pigment.
These issues extend to the use of other colours to create special effect pigments. For optimum results, the desired companion pigment should be:
- As transparent as possible, i.e. with minimal light scattering
- A highly chromatic (clean and bright) masstone, i.e. it maintains brightness in combination with other pigments.
True Blue
Hollliday Pigments’ Ultramarine Blue TR meets both these criteria. Its carefully controlled fine particle size distribution and similar refractive index to the majority of resin systems, gives excellent transparency. Furthermore, the position of ultramarine blue in the colour space is unique - no other pigment or combination of pigments gives such a chromatic, red shade blue. Therefore, in comparison with other commonly used blue pigments, TR works in synergy with the interference pigments, giving a final effect that is unmatched by any other combination(s) of pigments.
Put to the Test
To demonstrate this, sprayed panels were prepared using a coloured base coat and a clear coat containing the special effect pigment in a two-pack acrylic system. The pigments used in the base coat were Ultramarine Blue TR (PB29) at 17% pigment loading, Phthalocyanine Blue (PB15:3) at 4%, and Indanthrone Blue (PB60) at 3%, at levels to give an equal colour strength. The effect pigment in the clearcoat is Merck Colorstream Viola Fantasy (1%), a violet/blue angle-dependant pigment.
These were measured using a Gretag Macbeth AutoEye 641 at viewing angles of 20, 45, 75 and 110º. This gives an indication of the effect of changing angle, although it does not completely represent what is seen by the eye, which requires measurement of both multi-angle illuminant and observer.
The results, as demonstrated in the accompanying chart, show that the combination of pigment and special effect appears as follows:
PB60 A very flat and dull, red-shade blue with little colour change as the viewing angle is altered.
PB15 Good colour change through viewing angles but very green in hue and reduced chroma, resulting in a duller shade than desired.
PB29 Sample demonstrates good colour change through viewing angles, giving a very red, bright blue shade. Ultramarine TR is the only ‘true blue’ when compared with the other two panels.
The tests concluded that, within the blue colour space, Ultramarine Blue TR is the only pigment that truly works in harmony with interference pigments to give a unique finish and proven added value.
Comparison of the synergestic impact on special effect and blue coloured pigments
Ongoing Development
This type of ongoing research and development is fundamental to Holliday Pigments’ strength of position. In over 120 years of manufacturing Ultramarine Blue, its expert chemists have never stopped refining the production process, to develop grades which are best suited to specific applications.
For example, Holliday Pigments has recently made a major advance with a solution to the problem of maintaining pigment hue and intensity in acid conditions. While previously available acid resistant grades from Holliday Pigments had provided a good response to many of the difficulties posed under acid conditions, there were several specific parameters which needed further development.
Dissatisfied with the status quo, Holliday Pigments began researching the problem, which eventually saw the launch of its improved acid resistant grades 59 and Premier XAR for plastics in 2007.
Following the successful launch of its new generation acid resistant grades, the company is now developing further ultramarine grades with resistance to other corrosive elements. The findings of a study programme into the basic chemistry of the chromophores of ultramarine pink and violet is also influencing the design and operational procedures of recently installed capacity.
“The outlook for Holliday Pigments is very positive indeed. Our main focus at this time is research and development into harnessing new manufacturing techniques; enhancing our existing grades and exploiting our knowledge of ultramarine’s unique properties to perfect new pigment technologies,” concludes Glyn Jagger.
”We remain wholly committed to our goal of developing new, added value solutions for our customers and widening the applications scope for ultramarines. To this end we have substantially increased our existing research programme, extending collaborative arrangements with universities and, more recently, with our new parent Rockwood Color Pigments. The additional research programme represents a further €1.6M investment in the future of ultramarines technology and we look forward to producing more grades, like Ultramarine TR, that truly stand up to the test.”
-ENDS-
Notes to Editor: About Holliday Pigments
Holliday Pigments is the world’s leading supplier of ultramarine pigments, which are used in a variety of applications including plastics, coatings, cosmetics, artists’ colours and printing inks. Exporting to over 80 countries, Holliday Pigments has dedicated customer and technical service teams at its factory in France and its commercial office in Malaysia.
Holliday Pigments has a proud 120-year history in the manufacture of technical quality ultramarine and is the only ultramarine manufacturer in the world to have invested in Flue Gas Desulphurisation technology, reducing sulphur dioxide emissions inherent in the manufacturing process by more than 99.5%.
In August 2008, Holliday Pigments joined Rockwood Holdings Inc., becoming an important addition to the Color Pigments and Services Division. Rockwood’s Color Pigments & Services Division is one of the largest worldwide suppliers of colored pigments for construction, coatings, plastics and specialty applications. The Division’s manufacturing sites and customer service centers are located in the United States, United Kingdom, Italy, Germany, Australia and China with additional sales offices located in Singapore. For more information on Rockwood, please visit www.rockwoodpigments.com.
The Rockwood Color Pigments & Services Division is part of Rockwood Holdings Inc., Princeton, N.J., U.S.A. Rockwood Holdings, Inc. is a leading global specialty chemicals and advanced materials company. Rockwood has a worldwide employee base of more than 9,500 people and annual net sales of approximately $3.1 billion. The company focuses on global niche segments of the specialty chemicals, pigments and additives and advanced materials markets. For more information on Rockwood, please visit www.rocksp.com |