Polymer foils that are extremely thin and characterized by a high light scattering rate are being produced by a new process. This inexpensive material may be applied industrially to various objects to give them an attractive white appearance. Moreover, the process can make products environmentally more compatible.
A brilliant white surface makes furniture and other objects appear clean, bright, and modern. So far, titanium dioxide has been the standard pigment used for white colouring of lacquers, paints, and plastics, as well as of cosmetics, foods, chewing gum, or pills. Titanium dioxide has a very high refractive index, so it reflects incident light almost completely.
However, the pigment has a negative side. Its particles do not degrade and thus pollute the environment in the long term. In addition, there have been concerns that titanium dioxide could be harmful to health.
While there is no perfect replacement for TiO2, there are a number of substitute chemical products which, if handled correctly, can improve the performance of products. For example, lithopone, a co-precipitated zinc sulfide and barium sulfate combination, can act as a cost-effective alternative for TiO2. Calcined kaolins are a practical ingredient that has been specifically designed for high PVC paint, providing significant cost savings.
Titanium dioxide will remain the key ingredient for so many products requiring whiteness. But with prices showing no sign of decreasing, or even stabilising, chemical suppliers will need to be increasingly creative with the products they provide and the range of functional fillers and extender pigments they make available.
An innovative approach to solving this problem comes from biomimetics – materials and other technologies which are inspired by nature, the intention being to understand and imitate these natural events to make them technically usable.
A process developed by KIT’s Institute of Microstructure Technology (IMT) is inspired by the white beetle Cyphochilus insulanus, whose chitin scales appear white thanks to their special nanostructure. Based on this model, solid porous nanostructures, which resemble a sponge, are produced from polymers. This nanostructured polymer film produces a brilliant white coating.
“We avoid the use of pigments that are harmful to health and the environment by producing porous polymer structures of comparably high scattering efficiency,” says Professor Hendrik Hölscher of IMT. “Based on this model, we have produced polymer-based solid, porous nanostructures, which resemble a sponge.”
The structure scatters light in a similar way to the bubbles of shaving or bathing foam, which makes the material appear white. “The polymer foils produced by our process are extremely thin, flexible and light, but still mechanically stable and can be applied industrially to a variety of products,” adds Hölscher. At a thickness of 9µm, the newly developed polymer foil reflects more than 57% of the incident light. 80 to 90% can be achieved by increasing the thickness of the foil. In the course of the development work, the sponge-like microstructure was applied to acrylic plastics. However, the process may be transferred to many other polymers.
“As a next step, we plan to produce particles – small beads that are added to other materials,” Hölscher adds.
References
New Materials: Brilliant White without Pigments – https://www.kit.edu/kit/english/pi_2020_020_new-materials-brilliant-white-without-pigments.php
Whiter than white: options for the Compounder. Plastics Additives and Compounding, October 2002 – https://fdocuments.in/document/whiter-than-white-options-for-the-compounder.html
The views, opinions and technical analyses presented here are those of the author or advertiser, and are not necessarily those of ULProspector.com or UL Solutions. The appearance of this content in the UL Prospector Knowledge Center does not constitute an endorsement by UL Solutions or its affiliates.
All content is subject to copyright and may not be reproduced without prior authorization from UL Solutions or the content author.
The content has been made available for informational and educational purposes only. While the editors of this site may verify the accuracy of its content from time to time, we assume no responsibility for errors made by the author, editorial staff or any other contributor.
UL Solutions does not make any representations or warranties with respect to the accuracy, applicability, fitness or completeness of the content. UL Solutions does not warrant the performance, effectiveness or applicability of sites listed or linked to in any content.
Do we need to use TiO2 with Cyphochilus insulanus produces to make white the plastics?or we should only Cyphochilus insulanus ?
Please also send me more technical info.
Thank You.
No, there are approaches based on modelling the beetle pigment, such as this reference:
http://www.kit.edu/kit/english/pi_2020_020_new-materials-brilliant-white-without-pigments.php