Biocide-Free Water-Based Coatings

Posted by Performance Coatings Team on 09/02/2020

To prolong shelf life and maintain product quality by killing microbe formation, water-based coatings require biocides—and so do the dispersants that go in the coatings. The problem: biocides can be hazardous.

Biocide legislation continues to change rapidly and is becoming ever more restrictive. To meet the rapidly changing regulations, formulators continue to change the biocides they use in coatings and dispersants.

The MIT Challenge

Methylisothiazolinone (MIT) is one of the most common active ingredients used as a bactericide and antimicrobial substance in paints and coatings. It is added to many water-based paints to prevent microbiological contamination and the consequences that contamination can bring, such as a change of viscosity, gas formation, a pH shift or even unpleasant odor. Over the past 10 years, MIT has been one of the essential biocidal active ingredients in all preservation systems. It has been used as an alternative to, for example, formaldehyde releasers in consumer goods.

More recently, MIT is being looked at as a hazard. Hazard statements are part of the Globally Harmonized System of Classification and Labelling of Chemicals (GHS). A hazard statement is a phrase that describes the nature of the hazard in the substance or mixture.

H317 is a hazard statement related to potential skin sensitizers. As of May 1, 2020, it began applying to MIT in the European Union. Paints preserved with MIT will have to be labeled with the GHS 07 symbol (exclamation mark) plus the H317 phrase “May cause an allergic skin reaction.”

This new limit has fundamental consequences for the use of MIT as an active ingredient in preservation systems. Effective MIT dosages are usually in the range of 50 to 200 ppm. With the new specific concentration limit of 15 ppm, products preserved with MIT must now be mandatorily labeled with H317.

Overcoming MIT Dosage Limits

In the past, coatings containing ≥ 1000 ppm of MIT had to include the hazardous labelThe new labeling limit is now ≥ 15 ppm.  As dispersing agents have traditionally been diluted in water to improve their physical form, they often required the use of a biocide which now limits the flexibility for the formulator to produce GHS label free coatings.

Lubrizol has developed a solution to overcome this challenge:

  • Advanced dispersants that are 100-percent active, without water or biocide, for aqueous applications

With a water-free dispersant, there is no need for a biocide, and Lubrizol has developed several of these dispersants to give formulators more flexibility. By not adding biocide into the dispersant, the formulator can add their own biocide based on local regulations or use an alternative microbe deterrent technology, such as high pH paints. In addition, without the additional weight of water, transporting dispersants around the world becomes more favorable, since water has no real value in the final material, it’s just extra weight.

Advanced, 100-percent active dispersants from Lubrizol retain all the aesthetic and protective benefits of a dispersant in a paint formulation, including offering improved color development, significant viscosity reduction, faster dispersion, less settling of dispersed particles and higher particle loading while also being in a fluid physical form for ease of use.

Contact us to learn more about Lubrizol dispersants that can help avoid the use of biocides in your coatings.

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