Cork Tech Talk Blog

Digital printing has advanced continually since its introduction in the 1970’s due to electrophotography and inkjet having been the beneficiaries of the majority of development money spent on printing technology. Great improvements have followed in speed, quality, reliability, and scalability leading to new applications.

Read more: Inkjet, The Engine behind Digital Printing Growth

Aqueous coatings may be thermoplastic or thermoset, emulsion or solution polymer blends. The major volatile component is water along with small percentages of other volatile items. Some of these, such as ammonia or amine can evaporate and accumulate in the headspace of a sealed container, therefore opening is best done in a well ventilated area.

Read more: Aqueous Coatings: Storing, Handling & Using

Paper Substrates Forgive, Plastic Ones Do Not.

Much has happened since we last wrote about printing on plastic substrates. Compared to a few years ago, many more printers are printing on plastic substrates and the variety of available substrates has increased, as has interest in printing on these materials, the result of innovative new applications.

Read more: Printing on Plastic Substrates can be Tricky

WVTR & MVTR Permeation 

Many packaged products are sensitive to moisture therefore control of water vapor into or out of the package is critical to the contained product’s quality. The permeability of packaging materials has a direct effect on a packages performance in terms of the contained products shelf-life. This permeation by moisture is measured by WVTR (water vapor transmission rate) or MVTR (moisture vapor transmission rate). The primary purpose of packaging is to get the packaged product to the customer in one piece and suitable for consumption. Packaging plays many roles, containing and protecting products during distribution, storage, and use, while also promoting, educating, and selling.

Read more: Moisture and Water Vapor Transmission Rates in Packaging

Talk about a market change over! It wasn’t too many years ago that the blister card market was dominated by solvent based blister card coatings. Not only has the blister card market grown by leaps and bounds, but the dominating solvent based blister card coatings have been replaced by aqueous blister coatings. Additionally, what was formerly exclusively an off-line post print, second pass roller coating business has yielded more and more to higher productivity, inline, print/one bump coat production. Litho printers have for some time eyed the blister packaging market wanting to participate totally, and now they are.

Read more: Aqueous Blister Coatings Printed In-line

In California, Prop 65 requires the state to publish a list of chemicals known to cause cancer, birth defects or reproductive harm. The law requires a warning label on anything containing these. Benzophenone was listed in 2012. Benzophenone (BP) or Benzo, has been generally recognized as the most used Photoinitiator (PI) globally. It is known for its effectiveness as an initiator, and its relative low cost.

UV printing ink and coating manufacturers have responded by replacing low molecular weight, high migration potential PIs. As a result, benzophenone & ITX free formulations have been made available, notably for food packaging. In other moves, raw material suppliers continue to develop self-curing resin solutions, new large molecule, low migration, low odor polymeric photoinitiators (PPIs), and co initiators. Significantly, these changes have become price drivers for UV curing products.

Read more: California Prop 65 UV Coatings

Flexo style chambered doctor blade metering coaters have become the dominant coater type used on sheet fed offset presses. They have proved capable of producing high levels of precise, repeatable application of clear coatings, and other fluid products.

Integral to this success has been the development of the laser engraved ceramic anilox roll, which is durable and does not wear over time. This means that the cells engraved into the ceramic to carry a pre-determined volume of liquid are consistently the same.

Read more: Coatings & Anilox Transfer Efficiency To The Substrate

A number of news outlets have recently reported, referred to, and quoted the findings of a study conducted in 2014-15 by Silent Spring Institute. The study was published in the journal, “Environmental Science & Technology Letters.” It reported on the finding of chemical substances (fluorinated compounds), that have been linked with health problems and cancer, in some fast food packaging.

Read more: Media Reports Fluorinated Compounds in U.S. Fast Food Packaging
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About the Author

Elmer W. Griese Jr, having accumulated 35+ years of knowledge working in the coatings and printing ink industries has now authored the Cork Tech Talk News, newsletter since 1992 producing 112 issues. He remains dedicated to educating and illuminating technological progress that offers the potential to advance coating technology and its applications.

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