Undesirable odor in some adhesives is caused by many factors including raw material properties, manufacturing process parameters, storage, application, and aging.
Nature of the Raw Materials
Only low molecular weight substances (below Mw 294) produce an odor. Very often the presence of monomer residues like styrene, vinyl-acetate, and acrylic esters are responsible. Oligomers in C5, C9, and terpene resins are also a potential source, as well as by-products in natural resins like the sulphur containing molecules in tall oil rosins. Synthetic stabilizers and thioethers may develop a very unpleasant odor.
While an odor free, neutral behavior adhesive is the common expectation, it is particularly important in the automotive, medical, and disposable hygiene industries. Careful selection of raw materials will help in odor prevention. The Eastman hydrogenated
C9 hydrocarbon resins and
hydrogenated rosin resins are recommended for low to no odor applications requirements.
Adhesives and Odor, a lecture publication provided with permission from Collano AG, covers the following topics:
|- The mechanism of odor detection by the human nose.|
|- The nature of substances responsible for odor.|
|- Formulation strategies to prevent irritating odors in adhesives.|
|- Methods of odor detection and evaluation, present and future.|