The Value of Formulators

Posted on 2/11/2020 5:59:07 PM By David Speth

When I started college a lifetime ago, we were given a series of placement tests. One of them purported to determine our “specialization index” or something like that. This was supposed to tell us how likely we were to want to dive deeply into a subject-like getting a PhD. If I recall correctly, my “specialization index” was low telling me I should not be interested in a graduate degree but that I should enter the working world upon graduation.

Years later when I started my career in industrial research after my PhD in organic chemistry, I didn’t give that index score much thought. Looking back now, the test may have been more telling that I thought. Having spent most of my time in industry studying adhesives and adhesion, I find one of the attractions for me is that all the problems are different and they all require integrating multiple disciplines from mechanics, to surface analysis to organic chemistry. There truly is never a dull moment. 

Now that I have morphed into a formulator after years of developing new raw materials and technology, I am perhaps even more appreciative of the breadth that working in the adhesives industry demands. As a chemist or physicist one can now measure things down to the atomic level. We can even see single atoms on surfaces! Formulating however has an element of mystery and art. There are always multiple ways to design a product and even more ways to fail. Often the differences are subtle and difficult to measure. Developing the formulators magic touch requires lots of time and even more thought.

Hard core scientists, especially those in academia look down on formulators and similar application development professionals as a lesser level of the discipline since they don’t publish papers and often use semi quantitative, or even qualitative tests to develop a product. In this vein, I think of Ed Pluddeman from Dow Corning who developed the art and science of coupling agents. The story is that Ed did all his work using simple experiments. If two bonded glass microscope slides survived boiling water or a trip over the lights in his lab, the coupling agent was a success. In talking to Ed however, you realized that the instincts he used to evaluate these simple tests were based on years of very detailed science and an infinite number of experiments as well as hours and hours of study. This helped Ed solve a wide range of problems including those related to the Columbia shuttle disaster for NASA.

One area of dark art is the development of pressure sensitive adhesives. With the number of tackifiers available, there are tens of options for every application. Experience was the only guide until Jay Class and Sung Chu at Hercules expanded on 3M’s Carl Dahlquist’s criteria for tack using dynamic mechanical spectroscopy to unravel how tackifiers and polymers interact to product pressure sensitive behavior (J. Class, S. Chu, Journal of Applied Polymer Science Vol 30, 805 (1985). 

While Class, Chu and Dahlquist provide guidance, developing tack is still a dark art since there are many ways to measure tack (rolling ball, quick stick, loop tack, probe tack, etc.) which vary widely in terms of the test area and test rate. All can be informative, but none really captures the subtlety of how sticky the tape feels to an educated finger-which after all is how customers evaluate the experience. An experienced formulator is still required to provide the customer with the level of performance he or she desires. 

Another space of dark art is the concept of hot tack for hot melt adhesives. This property describe how strength develops as the melt cools before it solidifies. While there have recently been equipment developments to give us the ability to measure this for high molecular weight materials, it is still difficult to evaluate for the low viscosity formulations of hot melt packaging adhesives.

Qualitative tests are still more commonly used to inform formulators and customers on this performance property. 

Ultimately our ability to measure molecular properties may develop to the point where we can measure everything of importance with the accuracy we need to make formulation a scientific roadmap exercise. Until then we will have to rely on the art and experience of the formulation scientist to make our adhesives work.

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