“Sustainability is changing the way products are being designed, produced and discarded. It will certainly change the way we think about the raw materials that go into these products, and it will certainly have a major effect on the adhesives and sealants industry.”
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Table.
These days, sustainability affects everyone. It becomes
especially important when adhesives and sealants, as typical representatives of
cross-sectional technologies, are considered. In fact, both adhesives and
sealants are prominent examples of enabling bonding techniques, which allow for
improved sustainability in the first place. Consider lightweight and
fuel-efficient cars and airplanes; wind and photovoltaic energy generation, sun
heating and cooling, façade and glass insulation technologies; and the assembly
of components based on dissimilar materials - adhesives and sealants play an
important role in enabling more resource-efficient solutions at reasonable
costs for them all (and many others). In fact, the “indirect” footprint of
adhesives and sealants (by a magnitude of 100 to more than 1,000) dominates
over the “direct” impact through its composition and its specific use of
chemical resources for producing its base components, as well as energy
requirements for producing, shipping, packaging, and warehousing them.
The “indirect” impact is very specific and can by no means be generalized or
quantified; however, it is magnitudes larger than the direct footprint.
Consequently, adhesives and sealants manufacturers must provide the
best-performing product for a specific use area, a guaranteed life expectancy
of the bonded system regardless of physical or chemical attacks as specified,
and the respective assembly conditions at the beginning of the lifecycle,
including affordable recycling without down-cycling at their end. Only after
achieving this challenging set of goals - without any compromise on given HSE
requirements - can the question be addressed: to what extent can the same
product performance be achieved by further reducing the ecological footprint of
the adhesives or sealants formulation itself?
The route to achieve that is diverse, and may include lowering the amount of
adhesive per bond through performance improvements, the lowering or total
elimination of primering steps for surface preparation, the reduction of
packaging and transportation needs, and/or the substitution of materials
against those with a knowingly better sustainability performance. Bonding is,
in most cases, the preferred joining technique and offers the lowest overall
footprint. In the future, attention will be needed to define, specify and
quantify what sustainability and carbon foot printing is all about, and to
provide assistance to unbiased lifecycle assessments.
When discussing adhesives’ and sealants’ sustainability improvements, the usage
of raw materials based on natural or renewable resources (as opposed to
depletable sources such as crude oil, natural gas, and coal) is usually
considered. However, many forget that only about 0.006% of crude oil
equivalents relative to total output is used for manufacturing and formulating
the global tonnage of about 10.3 kt (dry) of adhesives and sealants forecast
for 2010.
2 What’s more, structural adhesion and
structural sealing, the two most demanding and fastest-growing segments within
the industry, call for ever more sophisticated, better-defined, and repeatable
chemistries than Mother Nature can provide.

Figure. Total Worldwide Production of Adhesives and Sealants, Including Share of Natural-BAsed Components
Adhesives and sealants are, in effect, applied polymers.
They began their success story with rapid progress in macromolecular chemistry
in the 1920s and 1930s, and have since been developed into highly specialized,
partly reactive systems specifically profiled for a very narrow field of
application. Performance as required is paramount, and meeting of all HSE
requirements a prerequisite. Thus, the use of renewable resources has declined
over time since 1920, as the figure indicates.
Raw materials based on natural sources have enabled interesting performance
characteristics, but they play a larger role only in low-to-medium modulus
application fields. Even in these applications, a chemical modification is
often needed to overcome natural quality fluctuations. The table shows benefits
and typical use areas of these materials.
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Currently, the use of natural-based raw materials will remain limited, and will
not be an option for high-performing structural applications. A realistic route
for reducing the “direct” carbon footprint could, under those circumstances,
open up with the enzymatic or catalytic breakup of biomass materials,
preferably agricultural waste not directly competing with human and animal
food. Nonetheless, responsible adhesives and sealants formulators are working
to reduce the relative carbon footprint, such as by replacing solvent-based
systems with water-based ones, lifting the solid content, improving the
robustness of given solutions, and thriving for more performance with less
material. Regulators and government authorities contribute to the ongoing
evolution as well, and continue to be one of the most important sources for
innovation. Better insight in bioengineering may one day change this scenario, namely
through green chemistry. For the time being, however, our industry will remain
dependent upon petro chemistry. In contrast, the adhesives and sealants
industry, through its enabling role, is contributing a lot to truly substantial
cutbacks of footprints across all markets - including transportation,
aerospace, woodworking, packaging, energy generation, electronics and
construction, which in total represent more than 90% of all CO
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emitted by man. This is something to be proud of!
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