SMI: Flexographic Inks

Flexographic Inks Formulated With Specialty Minerals’ Calcium Carbonates

Ground calcium carbonates (GCCs) are often used in flexo inks, but simply as fillers to take up space and reduce cost. Specialty Minerals Inc.’s (SMI’s) functional filler precipitated calcium carbonates (PCCs) can do that, and more.

Albacar^® 5970 and Calopake^® 5970 Scalenohedral PCCs
The unique crystal morphology of these scalenohedral, “starburst” PCCs can add value to water-based flexographic inks and corrugated carton coatings. High brightness and high opacity inks can be produced by substitution of regular filler. Because of the pigment spacing effects of the crystal’s size and structure, the amount of titanium dioxide or color pigment may be able to be reduced.

This scalenohedral crystal structure provides particles of high surface area, and high oil absorption, which can aid in building viscosity. For example, when the 1.8 micron PCC is dispersed in water under high shear for 10 minutes, the Brookfield RVT viscosities at 20 rpm are:

These are viscosities in only water. If excess viscosity is found in preparing high solids slurries, an appropriate pigment dispersant can be used to bring viscosity down.

Albacar^®5970 PCC is manufactured in the U.S., with a median particle size of 1.8 microns; Calopake^® 5970 PCC, produced in the U.K., has a median particle size of 2.0 microns.

Many of SMI’s PCC satellite plants also manufacture these scalenohedral PCCs in slurry form, which may be especially useful for water-based flexographic ink production. Click here to find if there is a supply location near you.

Ultrafine and Superfine PCC Functional Fillers
For formulations where very small particle-sized functional fillers are desired, PCC products with particle sizes of 0.07 or 0.7 microns would be the choice. These materials can help in developing high brightness and gloss inks, in which color development and opacity can be enhanced. Mild rheological control can result at moderate loading levels. Multifex-MM^® (in the U.S.) and Calofort^® U (in the U.K.) PCCs are uncoated nano, 0.07 micron, precipitated calcium carbonates. Stearic acid coating adds hydrophobicity and dispersibility in organic systems to the ultrafine Ultra-Pflex^® (in the U.S.) and Calofort^® S (in the U.K.) PCCs. Larger in size, but smaller than the Albacar^® 5970 PCC are Albafil^®, a 0.7 micron uncoated PCC, and Super-Pflex^® 100, the coated PCC version, for high quality inks of less than maximum demanded performance.

Vicron^® Ground Calcium Carbonates (GCCs)
When simple fillers are desired in flexographic formulations, SMI in the U.S. has a complete range of high-brightness, high-quality ground calcium carbonates (GCCs). The Vicron^® ground limestones range in size from 3 microns to 17 microns, and are manufactured in Adams, Massachusetts and Lucerne Valley, California. The RiverCal^TM 8100 series is also manufactured in the U.S.

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