Paint formulators face many challenges in today’s market, and are continuously in search of new innovative raw materials to satisfy the needs of their customers. In an effort to reduce cost, improve technical properties, and fulfill more stringent environmental regulations, chemists have started to look toward a class of products known as microspheres.
As the name implies, microspheres are small, spherical particles. Particle sizes range from 12 to 300 microns in diameter, and for hollow spheres wall thickness can vary from several microns to as low as 0.1 micron. They can be composed of acrylonitrile, glass, ceramic or phenolic materials.
The spherical shape is one of the unique features that differentiates these products from other non-soluble additives. For a given volume, a sphere has the smallest surface area of any shape and, because of this, microspheres have very low resin demand. Microspheres roll past one another like ball bearings, with no rough surfaces or branches to entangle.
Formulators can use microspheres to increase the solid content of a coating while maintaining the proper application and flow characteristics. Higher solids can reduce volatile organic compounds (VOCs), shrinkage and drying time.
The large volume that microspheres displace for a given weight is an important attribute in their use. Because hollow spheres will lower the density of materials they are added to, a gallon of coating will weigh less than the same product made without spheres. Lower-density coatings are cheaper to ship and easier to carry up a ladder. A low-density coating will atomize better, give less spatter when rolling, and sag less once applied. And since a small weight-addition of microspheres increases the batch volume significantly, formulation cost can be reduced.
Gotta catch 'em all!
There is a known tendency for the microspheres to float to the surface of low-viscosity systems, and they can also settle if they have a higher density. With the addition of cellulose fibrils, you introduce a spider web like 3D network of non-soluble micro fibers that can capture and hold microspheres in place, thus preventing the floating or settling of microspheres in your formulation.
The cellulose fibrils also has more to show for; multifunctionality through increased strength of the coating film and effective shear thinning behavior when applying the paint. This can create a high viscosity at rest due to the three-dimensional network, and at the same time products that are easy to handle during application. The high viscosity at rest is the key to keeping the microspheres in suspension, physically disabling the spheres (problem) of floating to the surface. This well may be an alternative to keeping your improvement in formulation cost going.
Try it out and look after the benefits I have mentioned, or start your screening by reading up on cellulose fibrils technologies.
* This blog post was originally posted on June 2017, but we have updated it to give you the latest news and ideas on the topic.
Scott Mouw has been working at Borregaard with the Exilva product line since 2015. Scott has a long experience from the field of coatings and pigments, as well as previously working with specialty chemicals.
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