Product failures can occur at various times during a product’s lifecycle and can be caused by coating or adhesive application, the base laminate, or during final packaging. It is important to discover the root cause of product defects which may come from simple observation or may require more sophisticated evaluation techniques. Technicians are often aware of the most likely cause and can help speed up troubleshooting when several potential factors exist.
Problems with the application of coatings and adhesives can produce defects in both appearance and lamination or packaging performance.
Common Problems with Coating and Adhesives
Foaming
When mixing coatings and adhesives for dilution or the addition of a co-reactant, foaming is a common problem that is often caused by improper mixing with the wrong size or angle of blade or by overmixing. Many systems tolerate additions of defoamers, although oftentimes changing the sump or pan can alleviate this problem.
Uneven appearance
The appearance of an uneven coating can manifest as voids, skips, grit, or gels and often leads to complaints of laminate appearance. Uneven application can also lead to problems in packaging performance. Common causes may include over shearing, excess idle time causing skinning of the adhesive, or improper mixing prior to application.
Skips, ribbing, and voids
These common defects are often caused by allowing excessive solvent evaporation during the application, applying the coating or adhesive outside of the suggested application solids range, and failure to monitor viscosity. These issues may come and go in a roll, or they can be prevalent throughout the entire roll. Operators need to follow adhesive manufacturers’ suggestions and monitor throughout the run. Be sure to use the correct volume and type of cylinder for the coating weight desired.
Appearance issues
Ink smears, ink bleed, and hazy lamination appearance are commonly associated when using solventless adhesives. Ink smear testing with suppliers is a good way to ensure compatibility with adhesive and ink systems. Water based adhesives that are under dried are a common cause of hazy laminations. Entrapment of small air particles can also cause hazy laminations; reducing foaming can address this issue.
Package performance issues
Package performance or laminate issues can occur early in the process or may not appear until the product has already been packaged for some time. Issues include poor heat resistance, low peel strength or bond, tunneling and/or delamination in the package. Make sure the correct adhesive is used for the end-use application and ensure that the mixing ratio if required, is correct. Ensure that all inks are dried completely and make sure that ink solvents do not compromise performance when interacting with adhesives.
Analytical Testing by Adhesive Manufacturers
Maintaining good quality control records of the type of coating and adhesive used during production can help determine the root cause of adhesive performance issues, although sophisticated analytical testing may be required.
Adhesive Manufacturer Provides Analytical Testing
Working with an experienced industrial adhesive manufacturer is one of the best ways to get to the root cause of any adhesion problems. Universal Chemicals & Coatings, Inc., UNICHEM, offers high-performance industrial adhesives and troubleshooting for customer adhesion problems. Our uniBOND industrial adhesive product line offers long-lasting adhesive solutions for laminating to metal, rubber, vinyl laminates, and more.
UNICHEM is an industry-leading adhesive manufacturer, offering high-quality, high-performance adhesive solutions to a variety of industries and applications. With more than 50 years of experience, our customers can have confidence in our high level of technical ability and custom development of adhesive solutions. Contact us to learn more and to get to the root cause of your adhesion problems.