Matte surfaces (EU) are a trend at the moment in the decorative paint market. However, these types of coatings get dirty easily and are difficult to clean due to their open and/or rough structure. As a rule, the higher the amount of filling (high PVC (EU)), the lower the gloss levels. The aim of this study was to show that it is possible for high PVC wall paints to have good surface resistance despite being matte.
Talc (EU) has a platy particle form and a very hydrophobic surface, which makes it very resistant to water and many other substances. But not all talcs are similar. There are many talc grades available that are blends of talc and some other, more hydrophilic, by-minerals. The purpose of this study was to investigate the effect of different talc types on the resistance properties of matte wall paint. The resistance properties studied were: water, water/ethanol (EU), stain resistance (EU) to achieve easy-to-clean properties, and dirt pick-up resistance. Four different talc grades were tested in this respect:
- FINNTALC M30SL from Mondo Minerals B.V.
- FINNTALC M40SL from Mondo Minerals B.V.
- CHLORITE TALC with 90% talc and 10% chlorite (Chlorite talc 10%)
- CHLORITE TALC with 50% talc and 50% chlorite (Chlorite talc 50%)
First, a guide formulation for an interior matte wall paint was developed. Then the different talc grades were added into this formulation, and the resistance tests were carried out after letting the different films cure for one week. The formulations prepared differ in type of talc and were with and without a silicone additive. In total, 8 formulations at PVC 70% were developed with the basic as follows:
Testing Water Resistance
To assess the water resistance (EU) of the coating after one week of curing, a big drop of water was applied on the film of paint and then covered by a watch glass in order to prevent evaporation. The damage caused by the water was assessed after 15min, 30min, 1h, 2h, 4h and 24h. The 24h results are shown below.
Testing water/ethanol resistance
To assess the water and ethanol resistance (EU) of the coating after one week of curing, a big drop of a 50/50 mix of water and ethanol was applied on the film of paint and then covered by a watch glass in order to prevent evaporation. The damage caused by the mixture was assessed after 15min, 30min, 1h, 2h, 4h and 24h. The 24h results are shown below.
Testing cleaning and stain resistance
Two types of stains were tested: coffee and green highlighter. A few drops of coffee were applied on the paint as well as a few stripes of green highlighter. They were cleaned afterwards and the possible remaining stains were assessed visually. For the formulations with different talcs, they were also assessed with a colorimeter (L,a,b measurement). The difference between the cleaned stain colour (2) and the white colour (1) were calculated with the following formula:
Due to the poor water resistance of the Chlorite (EU) talc based paints, the cleaning of the stain resulted in damaging the film and therefore no good determination could be made. The resistance and cleaning of the Finntalcs were good, especially FinnTalc M30SL, as can be seen in the following pictures:
Conclusions
Four different talc grades were tested: two of them were highly pure talc grades from Mondo Minerals (FINNTALC M30SL and FINNTALC M40SL) and two were talc grades with different amounts of chlorite from another supplier. The samples were tested for water, water/ethanol and stain resistance (coffee and highlighter). Dirt pick-up was also evaluated.
The paints with FINNTALC grades performed much better than the talc grade containing chlorite on all resistance properties tested. In particular the resistance to water and ethanol were much better with FINNTALC than with the talc grades containing chlorite. Also the coffee and highlighter pen stain resistance was better with FINNTALC compared with more hydrophilic talc-chlorite.
It was difficult to evaluate the stain resistance by colour difference measurements for the talc-chlorite grades, because they were damaged during the process of washing the stains. The poor resistance of the talc-chlorite to water used for washing was the reason for the damage during the cleaning. In terms of visual evaluation, it can be said that the FINNTALC grades tested had a higher resistance to surface cleaning than the talc grades containing chlorite.
This study has shown that with FINNTALC grades it is possible to improve the surface resistance in high PVC and matte paints. The silicone additive that was added to the guide formulations did not affect the performance of the FINNTALC grades, but improved the resistance properties of the talc-chlorite grades. Due to its excellent barrier properties, FINNTALC can compete with additives like silicones and waxes that are usually used to make paint films more hydrophobic in this type of paint.
Sponsored Products |
PLIOTEC® SA 40 by Omnova PLIOTEC® SA 40 is a carboxylated styrene acrylic dispersion used in coatings with excellent adhesion to concrete, water resistance and pigment binding capability… |
PLIOTEC® LEB18 by Omnova PLIOTEC® LEB18 is a modified acrylate copolymer designed for high performance exterior masonry coatings, thanks to OMNOVA’s Low Exudation Binder… |
About the Author:
After his study at the Vrije Universiteit (organic chemistry) in 2001, Sander van Loon worked for 7 years on the Marine and Protective Coatings laboratory of PPG. In November 2008 he founded the company VLCI, which provides R&D services to the formulation industry. He is currently the CEO of VLCI, a company with 7 persons, using HT screening and serving small to multinational customers over the world. For more information on Van Loon Chemical Innovations’ services, click here.
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.