100% Bio-based Dispersants for Water-based Carbon Black Systems

As part of our development work on the BioLoop range of dispersants, we have launched some products based on rapeseed oil. In this review, we look at some of our products in an aqueous carbon black pigment concentrate. These have been compared to the standard BioLoop range in which the Lansperse LT87 has been the product of choice for stable carbon black dispersions. However, this has only a bio-based content of around 40%. We look at 10 different dispersing agents utilising our standard Soybased BioLoops and the new Rapeseed BioLoops, along with our well-established synthetic-based range.

These were all premixed on a high-shear mixer and then bead milled on our Eiger laboratory mill for 30 minutes with 1.5 mm YTZ (yttria-stabilized zirconia powder) beads.

Table 1 below shows the best ones:

Rheology

Viscosity was measured on a DIN 4 flow cup over time, with the results displayed in Table 2 below and in graph form in Figure 1:

Figure 1

Gloss and Colour Measurements

The above pigment concentrates were diluted at 5% in a commercial high gloss Trade medium base.

These were then mixed on a Thinky Intertronics ARM-310 compound mixer for 5 mins at 2000rpm and then coated onto a LENETA card at 50 microns using a TQC automatic applicator.

Gloss was measured using a 20-60-85° tri-gloss meter and the colour measurements using a Konica Minolta CM-5 spectrophotometer.

Results in Table 3 from tinting in high gloss Dulux trade.

Conclusion

The results in Table 2 show that all these dispersants have stable viscosities but most of them increase slightly at the 30-day testing stage, and then at the end of testing (> 130 days) they return to their initial viscosity. However, the Lansperse RPS43 appeared stable over the whole test period.

The colour measurements show the typical L*a*b values of the Cielab colour space, shown below:

L*: Lightness, light or dark

a*: Red / Green (+ or -)

b*: Yellow / Blue (+ or -)

The results in Table 3 show that all samples are dark in colour, slightly green and blue.

The Lansperse BIO691 and Lansperse RPS43 are darker (blacker) than Lansperse LT87, but not as green and slightly less blue.

There are no big differences to all the products, but, potentially, if you need a 100% bio-based product, then the Lansperse BIO691 or the Lansperse RPS43 would be a good starting point.

Note: we always recommend a ladder study to optimise levels.

Product Samples