A new dispersing agent for aqueous based blue systems
Updated: Oct 15, 2020
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 of these have exceptional performance but the formulator now requires additives with better environmental credentials and also improved hazard labelling.
Lankem have 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. Of these Lansperse UV86 (100% activity) can be utilised in both UV systems and water based and hence along with its environmental benefits is a highly novel addition to the Lankem range.
Lansperse UV86 is:
High bio-based content
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.
In this blog, 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 and also an assessment of the film properties was undertaken.
The viscosity was analysed over time using a Brookfield viscometer.
Rheology is a very 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 a period of time shows that the Lansperse UV86 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 UV86 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 UV86 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 UV86
The results of the particle size analysis show that over the same period of time of dispersion, the one based on Lansperse UV86, achieved a lower particle size. This can lead to higher gloss and could be the factor which 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 UV86 which should give more stable dispersions.
The Lansperse UV86 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 rub area indicates the system is likely to flocculate.
As you can see there is very little flocculation observed in this test.
The Lansperse UV86 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.