White masterbatch’s performance comes down to how well its TiO2 is dispersed in the carrier resin, and research comparing dispersion methods shows a genuine trade-off: the same improved dispersion that gives better opacity also makes the pigment more photocatalytically active, leading to more yellowing under UV exposure. This page covers that research and how masterbatch color quality is measured.
What is it?
White masterbatch is a titanium dioxide (TiO2) concentrate used to whiten and opacify plastics. Color quality — including the yellowness that signals degradation or poor pigment performance — is measured instrumentally using ASTM D6290, a standard test method for determining the degree of yellowness of nearly-colorless or white plastics using a spectrophotometer, reporting results as Yellowness Index or CIE/Hunter L, a, b color values.
Why should I use it?
- Better TiO2 dispersion in the carrier resin gives measurably better covering power (opacity) — see “How it’s used.”
- Its color and yellowness can be objectively tracked over time using a standard instrumental method, not just visual judgment — see “What is it?” above.
How it’s used
In plastics and polymer applications, white masterbatch is diluted into a carrier resin to whiten and opacify films and other products. A 2020 peer-reviewed study compared conventional melt-extrusion against variable-frequency ultrasound-assisted extrusion for producing a 7 wt% TiO2 masterbatch in LLDPE film: conventional extrusion left “clusters of particles from one micron,” while the ultrasound-assisted method achieved better TiO2 dispersion and stronger covering power.
Limitations — when it isn’t the right choice
- Better TiO2 dispersion comes with a real trade-off: it also increases the pigment’s photocatalytic activity, which can accelerate yellowing under UV exposure. The same 2020 study found that “the deagglomeration process using variable ultrasound frequency increased the photocatalytic activity” of the TiO2. Both the ultrasound-processed and conventionally extruded films reached a similar yellowness index of about 1.5% at 400 hours of accelerated UV aging, but by 500 hours the better-dispersed, ultrasound-processed film’s yellowness index climbed further to 2.3%, exceeding the conventionally extruded film with its coarser dispersion. This means a white masterbatch optimized purely for maximum opacity through fine TiO2 dispersion may not automatically be the best choice for products facing long-term outdoor UV exposure; these figures are specific to this study’s LLDPE system, 7 wt% TiO2 loading, and UV aging test, and shouldn’t be assumed to hold at every loading level or exposure duration.
