Metal effect pigments

The term luster pigments includes metallic, nacreous and interference pigments. The luster effect is due to directed reflection on planar-shaped and ordered pigment particles. 

---

Two blue pigments can be prepared in transparent form cyanide iron blue and cobalt aluminum blue. These pigments are used in achieving a blue shade of the metal effect pigments in metallic paints. Transparent cyanide iron blue is prepared by a precipitation reaction similar to the one used for the preparation of the opaque pigment, but considerably lower concentrations of solutions are used. It is produced by Degussa (Germany), Manox (U.K), and Dainichiseika (Japan). 

Metal effect pigments, 29 411 Metal emission limits, 23 183 Metal extractants, 20 750 Metal extruders, for VDC copolymers, 25 726... 

As shown in Figure 71 A, conventional pigments interact with light by absorption and/or diffuse scattering (see Section 1.3). Luster pigments comprise nacreous pigments (Section 5.3.1) and metal effect pigments (Section 5.3.2). 

Metal effect pigments (Fig. 71 B) consist of small metallic flakes (mainly aluminum or Cu/Zn bronze) which act as small mirrors that reflect almost all of the incident light. 

Figure 71. Optical principles of conventional and luster pigments A) Conventional pigment that absorbs and scatters light B) Metal effect pigment with complete regular reflection C) Natural pearl composed of alternating layers of protein and CaC03 D) Nacreous pigment the pearl is simulated by parallel orientation of the pigment platelets...

Using a two-layer coating system in which an upper coat contains the nacreous pigment and the lower coat contains the hiding absorption or metal effect pigments... 

Definition. Metal effect pigments consist of flakes or lamellae of aluminum (aluminum bronzes), copper and copper-zinc alloys ( gold bronzes ), zinc, and other metals (DIN 55943, 55944 FSO 4618-1). 

Metal effect pigments regular reflection takes place on mainly flat and parallel metallic pigment particles (example aluminum flakes)... 

A) conventional pigment B) metal effect pigment C) natural pearl D) pearl luster pigment... 

The total market for effect pigments can be estimated to be about 50,000 tons per year. Half of this amount can be calculated to be special effect pigments, the other half to be metal effect pigments. 

Metal effect pigments are flake-shaped metallic particles supplied in the form of powders, pastes, pellets, suspensions or color concentrates [5.166-5.168]. Typical metal effect pigments include aluminum ( silver bronze ) and copper- and copper/zinc-alloys ( gold bronze ). 

Besides the metal effect pigments there are also metallic pigments and powders for functional coatings like anticorrosion, reflective, heat resistant and conductive coatings. These include zinc, stainless steel and silver pigments. 

Besides the bare metal effect pigments there is a whole variety of speciaUy treated or encapsulated metal pigments, to create new effects or to modify the pigment properties according to the needs of special appUcations ... 

One of the most typical properties of metallic pigments is their wetting behavior in different solvents (including water) or binder solutions. Metal effect pigments are basically divided into leafing and non-leafing types (Figure 5.29). 

Fig. 5.29 Wetting behavior of metal effect pigments leafing and non-leafing.

The main applications of metallic effect pigments are paints and coatings, printing inks and graphic arts as well as plastics and colorants (masterbatches). 

For the processing of metallic effect pigments in powder coatings, there are basically three possible technologies coextrusion, dry blending and bonding. 

Metallic effect pigments consist of small reflecting platelets. They mostly occur plane-parallel to the plastic surface. Pearl effects occur when the metallic effect pigment is colorless, or, at most, consists of thin platelets of iridescent color. Mother-of-pearl effects occur when orientation effects are also present. 

Metal effect pigments are mainly based on small metallic flakes of aluminium or bronze. In another class are mica-metal oxide multilayer interference pigments for perlescent effects. 

Figure 7-1 illustrates the various optical principles of conventional pigments (absorption pigments), metal effect pigments, and pearls and pear] luster pigments. In the case of absorption pigments, the interaction with light is based upon absorp-... 

---