Solenis has introduced new products in its imPress line of additives designed for papermakers looking to efficiently and cost-effectively produce papers with a 3-star rating for HP Indigo Digital Presses. Compared to the most common products on the market, the new imPress ID chemistries are up to eight times more efficient at generating Indigo print adhesion. Perfect image adhesion has been obtained with as little as 0.1 - 0.3% additive in the paper, which means mills can enjoy a number of benefits, whether they’re already making an Indigo-grade paper or looking to diversify by quickly adding an Indigo-grade paper:
Runnability. Specialty grades often require changing conditions at a size press. Not so with imPress paper additives. In almost every imPress run, no changes are required to size press or machine settings. And because the chemistry is a non-charged, clean, water-soluble formulation, it doesn’t form deposits, agglomerate, or cause stickies.
Versatility. The new imPress products play well with optical brightening agents and other size press chemistries. Typical size press types and setups can be easily accommodated, and any size press starch can be used. Plus, grades produced with imPress remain within specifications for other markets, such as offset printing, making the chemistry particularly versatile.
Performance. As noted above, the new Solenis products are up to eight times more efficient at enabling adhesion of Indigo images compared to top competitive products. Retaining the product at the surface of the paper, so it is in contact with printed ink, improves efficiency. A wide variety of basis weights have met the Indigo adhesion targets — typically only 0.1 - 0.3% of the product is required and less may be needed on certain base sheets. Papers produced with imPress additives also meet blanket compatibility targets, the other measure of 3-star qualification.
Support. Solenis has spent considerable time refining the imPress ID technology and understanding how and where it works best — both in the lab and in the mill. Our applications and technical staff are available to explain the technology, answer questions and help determine how much product will be needed for a particular paper base sheet. And our field sales team is available to run trials and make sure the product performs optimally in a real-world production environment.
Historically, polyethylene imine (PEI) was used to promote Indigo image adhesion. The Indigo ink is a liquid toner in which particles of poly(ethylene/acrylic acid) containing pigment are suspended in a light oil. The anionic nature of the ink was attracted to the cationic nature of paper treated with PEI. Unfortunately, papers treated this way were expensive to make and had yellowing issues. Mills and printers endured the cost because of the quality of Indigo printer images but continued to search for a better solution that addressed the unique chemistry of Indigo printing.
Over time, PEI was mostly displaced by size press treatments based on anionic poly(ethylene/acrylic acid) dispersions. Although they promoted adhesion, these dispersions were not efficient and led to runnability and paper quality issues. Solenis' imPress technology works differently, relying on thermodynamic attraction of the print ink to the paper treatment. Free energy drops as the ink and the treated paper interact with each other. As a result, adhesion is more efficient without the use of a dispersion.
The product can be made available for commercial applications in all regions. Currently, imPress ID-115 and ID-130 are available in North America, and imPress ID-215 and ID-220 are available in Europe.
For free technical advice and insights on how imPress ID paper additives can help you build your competitive edge, ask a Solenis expert today.