Simply stir in the pigment
26 Jun 2001
A development from BASF will make the production of aqueous decorative and industrial paints and coatings as well as aqueous printing inks much easier in future.
The company claims to have developed the world's first stir-in pigments for the coatings industry. These products have already been launched under the name Xfast and allow the safe and simple production of paints and coatings.
Unlike traditional pigments, the new stir-in pigments no longer require laborious processing before they are incorporated in paint or binder. The usual milling of the pigments is also a thing of the past.
Instead, the granules are simply stirred in, and the pigments develop their full tinctorial strength immediately. The new stir-in products are used in aqueous industrial and decorative paints. BASF expects to sell 500 metric tons of Xfast pigments in 2002.
Aqueous paints and coatings consist of a fine dispersion of a binding agent and pigments in water. In decorative paints the binding agent is usually a white paste known white binder by painters and decorators, whereas in coatings the binder is usually a clear, viscous liquid.
Pigments are very fine powders that are used to colour paints and coatings. Normal pigments, however, are associated with a major disadvantage: They stick together and form lumps if they are added to the binding agent without previous treatment. As a result, the powder does not disperse properly in the binding agent and the pigments do not develop their full tinctorial strength. In order to avoid lumps, the pigments must be milled thoroughly in what is known as a bead mill, which is filled with small glass and steel beads. Only then does the pigment powder disperse properly in the binding agent.
This milling process is a time-intensive step in the paint manufacturing process because equipment has to be cleaned every time a different pigment is used. A further disadvantage associated with the use of traditional pigments is that they generate a lot of dust.
The secret of the new stir-in pigments lies in their manufacture: The individual pigment granules are stabilized thanks to a surfactant coating. This prevents the pigment particles from sticking together. Instead of a powder that creates dust and easily forms lumps, Xfast pigments are supplied in the form of granules that disperse immediately in the binder system. In addition, the new products are free flowing and do not generate dust when processed. All the other properties of the pigments are identical.
BASF claims that paint production is considerably easier with Xfast pigments compared to traditional products. The finished paint can be obtained in the required colour intensity in the premixing container and bead milling is unnecessary. As a result, the paint production process requires less energy.
'Xfast pigments develop their full tinctorial strength after being added to a white binder and then stirred for a few minutes. These pigments have unlimited stability and are intended for use in water-based decorative and industrial paints or printing inks,' says Dr. Erwin Czech, Marketing Pigments for Decorative and Industrial Paints. BASF anticipates that the advantages of this delivery system will offer customers in the paint industry further scope for cost optimization in the manufacture of decorative paints.
Xfast pigments are already available in the four primary colours: red, green, blue and yellow. In the coming months, BASF will test the new pigments with several dozen customers. 'We will also develop Xfast pigments in additional colours if the tests show that the advantages described can be achieved in the production of coatings and decorative paints,' says Czech.
