Lankem have supplied dispersing agents for many years for the preparation of pigment dispersions and general coating applications. The main performers over the years have been both Lansperse DS200W and DS80. Both have exceptional performance, but the formulator now requires additives with better environmental credentials and improved hazard labelling.
Lankem has developed a range of dispersing agents based on our new BioLoop surfactant technology. These products tick all the boxes in terms of the requirements for modern coatings technology. In particular, Lansperse BA6 has found to perform extremely well in pigmented blue systems.
No label issues
Pigment Blue 15:3 is widely used in aqueous and UV inkjet systems. The one used in this study was Sinco Blue 4382-006 (Ex- Union Colours). This pigment has a clean green shade and high strength.
Below we look at a standard dispersant for water-based systems and compare it with some new bio-based products.
Work Carried Out
The following formulations were prepared by initially mixing on a high-speed mixer and then processed further on a laboratory bead mill. Analysis and comparison of the performance were made in terms of the dispersion rheology and stability. Also, an assessment of the film properties was undertaken.
Pigment Blue 15.3
*Lansperse BA6 is 40% active
The viscosity was analysed over time using a Brookfield viscometer.
Rheology is an important parameter as the formulator requires a dispersion that flows and is easily pourable. Also, another consideration is stability over time. A good stable dispersion should maintain good rheology after prolong storage and should not settle out.
The viscosity profile over some time shows that the Lansperse BA6 compares with the standard Lansperse DS200W, even though it is slightly higher in viscosity. This may be a dosage factor and we recommend a ladder series of studies to achieve the correct dosage.
Both Lansperse DS200W and Lansperse BA6 dispersions prepared as above were then mixed into a simple clear Styrene/Butyl acrylate binder system. This represented a basic paint formulation without any fillers but was essential to assess the relative performance of the dispersion in terms of pigment strength.
Both pigmented paint formulations were cast on the card as follows:
The drawdowns show that for this pigment the Lansperse BA6 gives a brighter (L* 48.42), bluer (b* -38.38) and slightly greener (a* -7.56) than the standard Lansperse DS200W.
Particle Size analysis
Particle size analysis was carried out on a Malvern Mastersizer 3000.
Lansperse DS200W Lansperse BA6
The results of the particle size analysis show that over the same time of dispersion, the one based on Lansperse BA6 achieved a lower particle size. This can lead to higher gloss and could be the factor that shows that the L* figure in the colour analysis is greater than the Lansperse DS200W. Also, the particle size distribution is narrower in the Lansperse BA6 that should give more stable dispersions.
The Lansperse BA6 was added at 2% into chalk paint. This type of paint gives an extreme assessment of whether the dispersion is likely to flocculate. The paint is then coated onto the card and the rub test is carried out. Any noticeable increase in pigment strength around the rubbing area indicates the system is likely to flocculate.
As you can see there is very little flocculation observed in this test.
The Lansperse BA6 performs as standard in this Pigment Blue 15.3 but with the added benefits of its environmental profile. This is another addition to our new generation of BioLoop surfactant technology for the ink and coatings market.