The Root of the Problem
April 2004
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A troubleshooting guide to COATINGS AND ADHESIVES.
by Kate Sharon, Associate Editor
COATINGS AND ADHESIVES are the unsung heroes of the packaging world. They protect a package and its goods, while making it look and perform exceedingly better than it would otherwise.
But when a problem arises in the application or formulation of a coating or adhesive, those protective, enhancing, and functional substances can be the sole reason for a job's rejection.
To get to the root of such costly issues and for ways to prevent them, packagePRINTING recently asked industry suppliers for their advice.
Coatings
Coatings play a very critical role in the cosmetic and performance makeup of a package. Aesthetically, coatings add shelf appeal with the ability to add a glossy, matte, or tactile finish to the package, explained John Signet, marketing manager of Water Ink Technologies. Performance-wise, coatings are a package's shield against scuffing, wetness, and chemicals, and they enhance the substrate's printability.
However, it doesn't take much for a coating to become the root of a problem. In fact, it's as easy as changing substrates or application methods. "In an effort to control costs and provide increased value for their customers, packaging manufacturers often look at changing the packaging substrates," explained Don Matthiesen, director of marketing and communication at Environmental Inks & Coatings. "Increased absorbency, material flexibility, reduced surface tension, and various slip packages may alter the immediate outcome and worse yet, cause failure days or weeks later." And, Matthiesen continued, "Changing the application method can cause a great product to yield poor results. In particular, the application rate will effect the flexibility, adhesion, COF (coefficient of friction), and rub resistance of a coating."
There are many factors to consider when trying to pinpoint and get rid of a coating problem, of which one of the most common is blocking.
Problem: Blocking
According to Don Duncan, director of research at Wikoff Color Corp., the most common press-side problem connected to coatings is blocking. Blocking occurs when the coating hasn't been completely dried or cured in the application process.
When a water-based coating hasn't been fully dried, sheets block in the load, Duncan said. And if a UV coating isn't agitated during printing, wax can be distributed unevenly also causing blocking.
Ambient conditions can also have an effect on coatings when using a thermal dryer on water-based coatings, said Stephen Lapin, vice president, technical director of Northwest Coatings. "It will be more difficult to dry the coating on a humid summer day compared to a dry winter day," he said. "Air movement in the dryer is very important for drying water-based coatings and is much more effective than IR heaters with little air movement. Adding more heat to the substrate is not always a good thing, and can actually make blocking worse if the heat remains upon rewinding or stacking of the material after drying."
by Kate Sharon, Associate Editor
COATINGS AND ADHESIVES are the unsung heroes of the packaging world. They protect a package and its goods, while making it look and perform exceedingly better than it would otherwise.
But when a problem arises in the application or formulation of a coating or adhesive, those protective, enhancing, and functional substances can be the sole reason for a job's rejection.
To get to the root of such costly issues and for ways to prevent them, packagePRINTING recently asked industry suppliers for their advice.
Coatings
Coatings play a very critical role in the cosmetic and performance makeup of a package. Aesthetically, coatings add shelf appeal with the ability to add a glossy, matte, or tactile finish to the package, explained John Signet, marketing manager of Water Ink Technologies. Performance-wise, coatings are a package's shield against scuffing, wetness, and chemicals, and they enhance the substrate's printability.
However, it doesn't take much for a coating to become the root of a problem. In fact, it's as easy as changing substrates or application methods. "In an effort to control costs and provide increased value for their customers, packaging manufacturers often look at changing the packaging substrates," explained Don Matthiesen, director of marketing and communication at Environmental Inks & Coatings. "Increased absorbency, material flexibility, reduced surface tension, and various slip packages may alter the immediate outcome and worse yet, cause failure days or weeks later." And, Matthiesen continued, "Changing the application method can cause a great product to yield poor results. In particular, the application rate will effect the flexibility, adhesion, COF (coefficient of friction), and rub resistance of a coating."
There are many factors to consider when trying to pinpoint and get rid of a coating problem, of which one of the most common is blocking.
Problem: Blocking
According to Don Duncan, director of research at Wikoff Color Corp., the most common press-side problem connected to coatings is blocking. Blocking occurs when the coating hasn't been completely dried or cured in the application process.
When a water-based coating hasn't been fully dried, sheets block in the load, Duncan said. And if a UV coating isn't agitated during printing, wax can be distributed unevenly also causing blocking.
Ambient conditions can also have an effect on coatings when using a thermal dryer on water-based coatings, said Stephen Lapin, vice president, technical director of Northwest Coatings. "It will be more difficult to dry the coating on a humid summer day compared to a dry winter day," he said. "Air movement in the dryer is very important for drying water-based coatings and is much more effective than IR heaters with little air movement. Adding more heat to the substrate is not always a good thing, and can actually make blocking worse if the heat remains upon rewinding or stacking of the material after drying."
Companies Mentioned:
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