Cork Tech Talk Blog

Setting & Drying Inks.

It’s all about the setting and drying of conventional sheet fed offset inks. Anti-set-off spray powder is used to prevent set-off, the unwanted transfer of wet ink to an adjacent sheet, in a press end pile. Spray powder not only provides a physical spacing between sheets of substrate, but also allows the circulation of oxygen containing air necessary to the drying (oxidation) of inks.
Anti-Set-Off Spray Powder

Sheetfed offset lithography is a printing process that feeds sheeted substrate into the press one sheet at a time for printing. After printing the sheets are stacked in the press end delivery section one sheet upon another in a pile.

Read more: 5 Spray Powder Usage Concerns

Cork Industries Formulates Benzophenone Free UV Coatings

Benzo Free Expert Help (610) 522-9550Photoinitiators (PIs) are a key component and a cost driver for UV curing products. They are capable, as their name implies, of initiating or starting a photoreaction. This occurs when a PI absorbs radiation energy from light exposure to produce highly reactive free radicals and ionic species. These have the capability of catalyzing or starting chemical reactions, or changes in certain formulated materials. One such photoinitiator is Benzophenone.

Benzophenone (BP) or Benzo, has been generally recognized as the most used PI globally. It is known for its effectiveness as an initiator, and its relative low cost.

In the last several years, a health concern has developed, especially in Europe, regarding the migration of small molecule PIs, into foods from indirect food contact packaging materials. It is thought that a PI like methyl benzophenone (MPB) can reach packaged food in two ways, (1) an indirect transfer from the vapor phase of semi-volatile PIs, (2) from direct contact stemming from permeation or set-off when cured printing inks and coatings come in contact with the inside of a package surface as packaging material is stacked or processed in roll form. When migration into food has been found, the packaged food and the packaging materials used have been removed from use.

Read more: Benzophenone Free UV Coatings and California Proposition 65

Before soft touch finishes we had to live with hard surfaced materials that were converted into products designed for our use. Think about it! Metals, stone, glass and wood are hard surfaced materials. Most plastic materials are hard surfaced materials, especially those that are used for non-disposable products manufacture.

Soft Touch GrowthThere has been exponential growth in the use of plastics recently due to the attractiveness of light weight, low cost and durability.

Plastic materials have found a tremendously wide range of applications because of these positive attributes. Plastic materials also have a negative side in that they tend to yellow after long term weathering, and are subject to scratching and chemical attack.

Read more: Soft Touch Print Coatings Deliver Perception of Quality

EB Curing Flexible Packaging Breakthough Evolving

EB technology applied to flexo and offset CI presses are competing to be a major factor in the future of flexible packaging.

Electron beam technology is widely used in a variety of industrial applications, including wide web offset printing/coating, food preservation, food packaging & medical products sterilization, polymerization, transformation and cross-linking of plastic films, cross-linking of wire/cable insulations, welding, and the evaporating of metals.

What is EB curing? 

Central Impression ChamberEB curing is a process wherein electrons are generated in a closed environment so as to impact specially formulated inks and coatings causing cross linking (polymerization).

Read more: Electron Beam Flexible Packaging

With the global customer base for retailed food increasing, food packaging must more and more conform to international food quality, and safety standards. This also can mean longer shelf life is a necessity.

Increased global consumer awareness, income, combined with busier lifestyles, is creating a growing demand for convenience foods. Consumers typically want the food they buy to be safe to eat, stay fresh longer, and meet their taste, and appearance preferences. Essential to this end is food packaging that can extend shelf life, and maintain food freshness.

Barrier CoatingsSimply stated, consumers want protective economic food packaging that offers easy open, and see through features, combined with barrier protection from degrading oxygen, water vapor, and aromas.

Read more: Barrier Coatings for Food Packaging

Work & TurnWork & Turn is a term used to describe the sheetfed litho practice of printing on both sides of a substrate. Typically, the first printing pass prints one side of the substrate. A second printing press pass follows as the job is turned and fed through the press again. The second pass can commence after the first pass inks are set and/or dry enough avoiding offsetting.

UV or hybrid(UV) inks are immediately cured (dry) enough to turned and second pass printed without drying time delays. Conventional sheetfed offset (litho) inks and overprint varnishes are based on resin systems and oils that set and dry by time dependent absorption and oxidation. Spray powders are used to dust these conventional litho inks and varnishes to prevent offsetting to the adjacent sheet back, when sheets are stacked in a pile at the end of a press.

Read more: Work & Turn Aqueous Coatings
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