Seeking the rainbow s end

Transcription

1 Seite/Page: 1 Seeking the rainbow s end The desire for individuality, functionality and sustainability at optimal cost are drivers for the development of pigments Recent introductions include new types of pearlescent effects; a highopacity organic red; an inorganic orange with improved fastness and bright colour; sophisticated pigment blends, and dark infra-red reflecting pigments, which reduce solar heat gain New colorants offer enhanced effects, durability and environmental benefits Christine Burgert Angela Giubilaro Rainer Henning* Tom Landuydt Marc Maurer Bill Nanson Three of the main trends driving the technical development of pigments today, which apply to all market sectors, are: A high demand for individuality and personalisation ; The need to extract maximum value from customersupplier interactions; A strong focus on sustainable growth Responding to market demands, we are focusing on creating new visual effects, enhancing technical performance and increasing cost-effectiveness Recent developments focused on personalisation include a novel colour-travel pigment technology and new pearlescent effect pigments that allow individual stylings and effects, widening choice for designers and consumers The ever-increasing drive for added value has led to the creation of sophisticated pigment blends and new organic pigments with higher colour strength and saturation Continuing efforts to ensure that growth and sustainability go hand in hand have resulted in new inorganic pigments with improved fastness levels that extend the colour space for certain coatings, while replacing carbon black by pigments that are transparent or reflective in the infra-red range reduces peak temperature and thermal stress, and prolongs the life of the coated substrates Each of these three trends provides an opportunity to innovate and offer new, commercially attractive solutions Some key recent innovations are described below Focus on personalisation widens choice Whether for consumer goods, teletronics, wallpaper or packaging, designers are always looking for something new to make their products stand out from the crowd, while consumers, for their part, are often looking for individuality and exclusivity New developments in pigment technology that allow new colour stylings and novel colour effects can widen choice for manufacturers, designers and consumers alike Organic pigments have been well established in the coatings industry for many decades They are well known for their high colour strength and transparency as well as for their chromatic effects Today, a wide range of chromophores is available and all kinds of imaginable shades are offered by pigment and coating manufacturers Organic effect platelets create new design opportunities One of the most recent innovations is based on new effects created by compounds manufactured in the form of organic effect platelets The intrinsic colour of these materials is closely linked to their chemical structure and the alignment of the molecules in the crystal lattice However, the specific shape of the particles allows new phenomena to appear, caused by the combined effect of light reflection, transmission and scattering, so that a deep colour-travel effect can be obtained (Figure 1) A finishing process based on crystal manipulation allows the product to be grown in platelet form so that it becomes an interference pigment with unusual differences in transmission and reflection colour (Figure 2) Because of its platelet form, the colour observed in reflection is progressively replaced by the one seen in transmission when the viewing angle is varied This new effect pigment is based on 2,9- dichloroquinacridone, which has been known and used for decades in coating applications and is inherently suitable for transformation into an organic effect pigment, because it can develop a variety of colours and effects, depending on crystal size and shape In the pigment s original, needle-shaped morphology (>200 nm), red/violet shades with strong hiding power can be obtained At an average size of about 200 nm, colour strength increases and the hue becomes magenta Finally, at a particle size of around 50 nm, the transparent orange crystals develop a bluish flop shade, which is very popular in automotive coatings Throughout these smooth changes from red to magenta to orange, the colour strength always remains very high, which is the main advantage of this chromophore over other mid-shade red pigments The first commercial pigment of this type, "Xymara Fireball", is suitable for a very wide variety of high-performance coating applications, including automotive and consumer goods such as mobile phones and electronic devices, and also for plastic coatings and masterbatches, as well as for inks Since this is a new form of an existing pigment, the flexibility and durability of the original chromophore is retained, and properties such as fastness, gloss and stability remain unchanged In addition, the visual appeal is not impaired by abrupt colour jumps The highly durable, transparent pigment offers stir-in performance and is suitable for both water- and solvent-borne formulations Applied as a stand-alone pigment in coating applications, quinacridone platelets offer a colour range that varies from orange/gold to a deep cherry red, as the angle of observation changes (Figure 3) With its thin, flake-like particles (Figure 2), the new pigment adds a discreet sparkle when used in an effect colour formulation Inherent transparency makes it suitable for use in combination Vincentz Network +++ Plathnerstr 4c +++ D Hannover +++ Tel:+49(511)

2 Seite/Page: 2 with different chromatic pigments as well as in multilayer paint systems, giving new, unusual effect shades with exceptional depth The range of options available is further extended if this pigment is used in combination with metallic and mica pigments The metallic shades that result from a combination with aluminium flakes are attractive and eyecatching in automotive applications, for example A new generation of whiteness is born Another effect much in demand today is pearlescence Conventional pearl pigments based on mica flakes with a titanium dioxide coating typically show a yellowish tint due to iron impurities in the natural mica In contrast to these, synthetic mica substrates are absolutely transparent and free of coloured impurities BASF recently launched "Glacier Frost White" a new pearl pigment based on synthetic mica This pigment allows the formulation of neutral to slightly bluish white pearl shades Optimized tri-coat formulations allow whiter whites to be produced at all observation angles (see Figure 4) The product can be used in combination with carbon black to produce neutral greys and high-quality blacks with a slightly bluish appearance Enhanced pigment performance adds value to coatings There is ever-increasing pressure on all suppliers in the market to reduce prices Yet this is not an approach that leads to long-term sustainability The alternative is to deliver products that offer more in terms of performance and thus extra value for the customer and supplier alike One recent development designed to achieve this is a pigment with higher colour strength and saturation The consequent reduction in pigment addition not only increases cost effectiveness, but can also improve technical performance, since the lower the pigment concentration, in general the better the overall film properties For opaque coatings, the fact that less pigment is needed to achieve a certain shade at a certain film thickness will mean that an associated increase in opacity of that pigment is required if all aspects of the coating are to be matched - and this extra opacity additionally creates an opportunity for primer-free coatings However, improved, more costeffective colour properties must not be allowed to impair durability Recent product introductions such as "Irgazin Solid Red" offer coating manufacturers higher value in use This pigment allows paint end-users such as car manufacturers to work with standard neutral primers instead of having to use coloured primers to offset the low hiding levels of solid red shades This provides greater flexibility and latitude in application when using a primer-free concept The new product offers better saturation than other CI Pigment Red 254 products, together with high colour strength and hiding power and excellent durability, even in the highly saturated yellow-shade red area Excellent flow and gloss, and high resistance to chemicals, solvents and bleeding can also be achieved These overall properties make it suitable for premium architectural paints, for industrial paints in general, and for automotive coatings New range of tailor-made pigment blends introduced Another customer-focused approach is the recently introduced "T-Shade" concept These sophisticated premilled pigment blends are tailor-made for the specific and individual needs of customers The highly homogenised combinations of ideally matching pigment chemistries are designed to achieve a wide range of properties and colour spaces in order to meet the required performance profiles At the same time, processing costs can be reduced for all types of coatings, including powder, coil, and water- and solvent-borne Shades can range from specific corporate colours, RAL and NCS for example, to mono-pigment blends Orange is latest innovation in inorganic pigments Sustainability has become a crucial aspect of all developments today BASF offers a very broad combined portfolio of organic, inorganic and effect pigments plus pigment preparations Conformity with global legislation such as the REACH regulations in Europe is one of the building blocks for sustainability In addition, professional consultancy is offered to coatings producers, to assist them in their efforts to formulate lead-free paints, for example Another recent development from BASF is "Sicopal Orange L 2430", an inorganic pigment with high chroma and colour strength combined with excellent temperature and weather resistance This product allows customers to formulate colours in the orange and red shade area with improved weather resistance and extended repaint intervals This feature is particularly valuable in silicate paint finishes, where organic pigments cannot be used (see Figure 5) These properties help to provide differentiation in offerings to end-users Pigments that keep paints cool Another hot topic is the formulation of cool paints Rising energy costs, pronounced urban heat-island effects and global warming all increase the need for intelligent solar heat management solutions When the energy radiated by the sun is absorbed by coloured surfaces, this generates heat, which is then transported by thermal conduction into the material and by convection into the surrounding air Reduced energy absorption automatically means less heat build-up Reflection from the colour-coated surface helps to significantly lower the temperature in the adjacent interior, to lower surface temperatures and thereby to lower temperature-induced stress in the coating itself and the coated substrates, prolonging the life of the coated system Paint films are normally applied as top coats at a thickness sufficient to give good visual hiding However, some transparency may remain in the invisible infrared range To minimise heat build-up, this transparency can be offset by: higher pigment concentration in the top coat higher film build in the top coat special pigmentation of the lower paint layer(s) or the substrate Another solution is to use in the top coat dark pigments with infrared-reflecting properties such as "Paliogen Black L 0086" and/or "Sicopal Black K 0095" These have a different colour profile from that typical of Pigment Black 7 (see Figure 7) These pigments provide a solution for formulating any dark colour with less infrared absorption than conventional black pigments The future for colours remains bright This article has focused on the trends that are currently driving the technical development of pigments These Vincentz Network +++ Plathnerstr 4c +++ D Hannover +++ Tel:+49(511)

3 Seite/Page: 3 trends in turn derive from factors that also affect other industries and, indeed, all aspects of life Today s sombre economic situation is leading to greater efforts to contain costs, yet is also promoting the trend for bright, sparkling colours and effects Globalisation and a growing world population contribute to the need for both brand consistency and colour uniformity on the one hand, and the desire for differentiation and individuality on the other All registered trademarks quoted in this article are the property of BASF SE Results at a glance Some novel pigment developments are reviewed which seek to meet key demands in this market: the search for individuality, maximising value in customer-supplier relationships and the need for sustainable growth Controlled recrystallisation of 2,9-dichloroquinacridone has created a colour-travel pigment with high colour strength and marked colour shift A pearlescent pigment based on a synthetic mica with high lustre and brightness gives a "whiter" white appearance An organic red pigment with improved opacity creates highly saturated reds with less need for coloured primers A new range of tailor-made pigment blends provides maximum pigment efficiency with rapid incorporation into the coating A new bright orange inorganic pigment extends the colour space and offers new technical options for coatings Reformulation of dark colours with infrared-reflective pigments reduces heat build-up and air-conditioning costs in hot climates Vincentz Network +++ Plathnerstr 4c +++ D Hannover +++ Tel:+49(511)

4 Seite/Page: 4 Figure 1: New effects achieved with organic effect platelets Vincentz Network +++ Plathnerstr 4c +++ D Hannover +++ Tel:+49(511)

5 Seite/Page: 5 Figure 2: Microscopy images of the platelet form of quinacridone: left, scanning electron microscopy shows platelets with average thickness nm; right, transmission electron microscopy shows the planar dimensions of 5-10 µm Vincentz Network +++ Plathnerstr 4c +++ D Hannover +++ Tel:+49(511)

6 Seite/Page: 6 Figure 3: "Xymara Fireball" can be used alone or as a shading agent: the platelet quinacridone form provides a copper-bronze face colour, deep cherry red flop colour, subtle sparkling appearance and is semitransparent (more opaque than most micas) Vincentz Network +++ Plathnerstr 4c +++ D Hannover +++ Tel:+49(511)

7 Seite/Page: 7 Figure 4: Colour properties at different angles: at an angle of 15 ; "Glacier Exterior Frost White" shows higher lightness and a much bluer pearl shade than a pearl effect based on natural mica Vincentz Network +++ Plathnerstr 4c +++ D Hannover +++ Tel:+49(511)

8 Seite/Page: 8 Figure 5: Colour profile for silicate plaster finishes, which must contain no organic pigments: "Sicopal Orange L 2430" extends the colour space to previously unattainable pure orangered shades Vincentz Network +++ Plathnerstr 4c +++ D Hannover +++ Tel:+49(511)

9 Seite/Page: 9 Figure 6: Influence of pigment composition in primer on total solar reflectance (TSR) values; top coat based on "Paliogen Black L 0086" Vincentz Network +++ Plathnerstr 4c +++ D Hannover +++ Tel:+49(511)

10 Seite/Page: 10 Figure 7: Cool "black" pigments in alkyd melamine paint, showing colour characteristics in white reduction (Skandex grinding, 4 hours) Vincentz Network +++ Plathnerstr 4c +++ D Hannover +++ Tel:+49(511)