I have been formulating adhesives and coatings since 1956, and in those years have seen government policies and regulations change entire industries, some justifiably, others not so justifiably.
In the early years, some adhesives and most coatings had to meet severe fire-retardance tests. Adhesives, being sandwiched between two substrates, and therefore having less exposed surface, were faced with far fewer and less stringent restrictions than coatings. Flame-retardant additives were, for the most part, expensive, calling for judicious use of the products, using just enough to meet the requirements.
In those years, Monsanto had a marvelous chlorinated resin/plasticizer/fire retardant series trade named Arochlor. Available in both liquid and solid forms, covering a multitude of melting points and a broad range of chlorine contents, these resins imparted flame retardance to a host of varied products. Soluble in many organic solvents, they could be added directly to solvent systems. They could also be emulsified for addition to water-based systems. Formulations could be modified with these resins to meet the most stringent test requirements.
Distillation, an important procedure in the course of the manufacture of each Arochlor resin, resulted in a dark, residual, high chlorine content still bottom as a by product requiring disposal. For years, these still bottoms were buried at various sites, until someone decided to market them as cheap, chlorinated fire-retardant resins. They could be coupled with asphalt to make low-cost, fire-retardant roof coatings, whereas previous efforts to fire retard inexpensive asphalts were cost prohibitive. Suddenly, the still bottoms became a series of marketable products rather than a landfill. These became the Montar series of resins.
Those of you in the industry at the time probably recall the publicity surrounding the sudden, mysterious decline in the peregrine falcon population. Apparently, something was responsible for the incomplete formation of the falcon eggshells, leaving them thin and extremely vulnerable to breakage. This was ultimately traced to residual quantities of these chlorinated resins.
These were the polychlorinated biphenyls and polychlorinated polyphenyls that became so notorious under the general designation PCBs. When they were withdrawn from the marketplace, they left a tremendous void, which formulators found difficult to fill.