For adhesives or coatings, ask the right questions

Published: March 01, 1996, By Bentley, David J., Jr.

An attendee at a recent technical conference was bemoaning the fact that adhesive suppliers did not help their customers as requested. The specific complaint was that the standard answer from manufacturers to any pleas for assistance was always the same: The composition of the adhesive is proprietary. Since adhesives and coatings have many similarities in use, let's discuss this problem as it relates to both.

Most suppliers are anxious to assist their customers to the best of their ability, but formulas of adhesives and coatings are secret for competitive reasons. Converters also have proprietary aspects of their operations. The success of many businesses hinges on the ability to do something a competitor cannot easily copy.

We should therefore consider what questions are proper to ask an adhesive or coating supplier when one has trouble using products satisfactorily. The first and most obvious question should concern its intended use. Is this the proper material - was it designed by the manufacturer for the application under consideration? Is it too highly designed for a simple application, or does it have insufficient characteristics for a more demanding application?

Ask about the physical properties - the solids content, the viscosity, the pH for aqueous systems, and so on. If these vary considerably from the adhesive or coating normally used, some compensation in running conditions may be necessary.

Other logical questions concern recommendations from the manufacturer for amount of dilution, deposition weight, drying temperature, curing conditions, and similar considerations. The supplier will have run the product in developmental trials and can probably offer suggestions for initial mixing and machining conditions.

Questions on the cohesive and adhesive strengths of an adhesive or coating compared with a known product can provide insight. Cohesive strength is the internal strength of a product. An adhesive or coating with a high cohesive strength will not fail internally as readily as one with a low cohesive strength. Adhesive strength is a measure of the ability to adhere to a substrate. Higher levels therefore provide better adhesion.

Also appropriate might be questions about specific adhesion. Does the adhesive or coating under consideration have specific adhesion to polyester, polyolefin, polyamide, and other substrates? Is flame or corona discharge treatment a requirement to enhance adhesion to a substrate?

You might inquire about performance. Does the product have any degree of chemical resistance? What is the heat resistance? What are the aging and performance characteristics over time?

Clearly one can obtain vast amounts of information about an adhesive or coating without knowing the formula or having the slightest hint of its chemical composition. The answers to the above questions have much greater value in effective use than any proprietary information.

One should therefore never criticize the supplier of an adhesive or coating who will not reveal the formula of a product. The manufacturer is merely protecting business, as everyone does. Instead, ask questions that will provide answers to help with your particular end use. Any adhesive or coating manufacturer who wants your business will be happy to answer these questions. Working together in this fashion will ensure a partnership that yields success. The key is simply to ask the right questions!

Editor's Note: Paper, Film & Foil CONVERTER is happy to welcome David J. Bentley Jr. to our pages as a contributing editor. His column on polymers, laminations, and coatings will appear every month. Dave has a degree in chemical engineering from the Massachusetts Inst. of Technology and over 30 years of experience in the research, development, and technical service of products used in flexible packaging, coatings, pressure-sensitive-adhesive applications, and graphic arts laminating. He has also specialized in the regulatory concerns of the converting industry. Currently VP of RBS Technologies Inc., Dave has held positions at Morton International and National Starch and Chemical Corp. He is a member of the American Chemical Society and TAPPI and is a TAPPI fellow, a former member of their board of directors, and a former chairman of their Polymers, Laminations, and Coatings Div. Dave has been a featured speaker at universities and professional and technical societies, and his writings have appeared in many journals.

David J. Bentley Jr. is a recognized industry expert in polymers, laminations, and coatings with more than 30 years of experience in R&D and technical service.