Questions and answers in the adhesives and sealants industry.

Q: I am a forensic technologist in the floor-covering area. I am often faced with bond failures when bonding floor coverings to sub-surfaces. Any help would be appreciated.

A: In analyzing bond failure, my first objective would be to see exactly where the bond is failing. Is it failing between the floor covering and the adhesive or between the adhesive and the sub-surface? If the failure is between the sub-surface and the floor covering, the problem is most likely due to something on the surface of the sub-surface or something being leached out of the sub-surface. Are there contaminants on the surface, such as dirt, dust, oily residues or waxes?

Secondly, is the type of adhesive being used recommended or formulated for that type of substrate? This question can be easily answered by the adhesive manufacturer, who will recommend the best type of adhesive for a particular surface.

Another common problem often associated with floor-bonding failure is due to plasticizer migration. All vinyl flooring contains plasticizers that may migrate into the adhesive over a period of time and cause the adhesive to turn soft and lose its tack. This is especially true if the adhesive is formulated with a synthetic rubber. Using an adhesive that is not affected by plasticizers often prevents the problem. Acrylic adhesives are less prone to failure caused by plasticizer migration.

If you are bonding to concrete flooring, find out how new the concrete is, as well as if there is any water seepage. New concrete may still have much efflorescence coming to its surface that can cause bond failure.

-ROGER LOHMAN

Q&A Exchange draws on the collective expertise of the staff of The ChemQuest Group, Inc., a management consulting firm specializing in the adhesives, sealants and coatings industries. Dr. William E. Broxterman serves as president of this specialist consulting firm. Questions for publication should be directed to him at The ChemQuest Group, Inc., 8170 Corporate Park Dr., Suite 317, Cincinnati, OH 45242; 513-469-7555; fax: 513-469-7779; Web site www.chemquest.com.