Adhesives & Biobased Technologies

January 24, 2013

Wow...last week saw one of the first real major breakthroughs in the movement to renewable biobased materials usage in adhesives. As other markets have been making great strides in finding biobased options for traditional petroleum based chemistries, formulated packaging adhesives have been left out. This challenging situation is primarily due to low volume opportunities available in the very diverse specialty niche substrate specific applications represented by adhesives. The announced partnership between Henkel and DaniMer Scientific to develop a global family of biobased hot melt adhesives for consumer packaging (folding carton, corrugated and PSA label) is significant because it marks the first effort to realize a sizable volume with a formulated biobased system, especially for traditional packaging hot melts.

To avoid confusion on the definition of biobased, the SPI definition is “the fraction of the carbon content which is new carbon content made up of biological materials or agricultural resources versus fossil carbon content (old carbon). Biobased content is measured following the procedures set by ASTM D6866”. SPI defines a bioplastic “as a plastic that is biodegradable, has biobased content or both”.

The base polymer (EVA, styrenic block copolymer) replacement with a biobased alternative polymer has been the most elusive in developing biobased hot melt adhesive systems. DaniMer said their feedstocks used to produce the adhesives are not derived from direct food chain resources and that their technology has also enabled the company to use recycled renewable content in certain adhesive grades. DaniMer’s sister company, Meredian, produces an arsenal of biobased polymers using polylactic acid (PLA), starch and polyhydroxyalkanoate (PHA) although the exact polymer family being used in the partnership has not been announced. The significance of this partnership is:

• DaniMer’s technology is in the synthesis process not necessarily in the base polymer. They can use a variety of biomass and agricultural products to achieve necessary polymer properties. Having said that the base polymer in packaging case and carton closure applications is still critical in adhesive formulation as the polymer provides strength, viscosity (peel strength) and hot tack. Many renewable polymers like PHA and PLA are not elastomeric enough, too crystalline and too stiff and brittle to serve as a good general purpose hot melt base polymer with properties matching the traditional petroleum ethylene vinyl acetate (EVA) polymers used for these packaging applications. One final biopolymer property is compatibility with the tackifier and wax formulation components necessary to have a successful peel, tack and shear.

PSA label hot melts today are based on styrene-block copolymers. They provide different properties and generally have a higher percent of base polymer than the EVA case and carton closure adhesives. Danimer other partnerships outside of the Henkel relationship with Myriant, bio-succinic acid and DuPont Tate & Lyle (DTL), bio-PDO (1, 3 propanediol) provide these biobased raw materials as building blocks for their hot melt PSA offering.

DaniMer claims its hot melt PSA adhesive is designed to meet the demands of PET container packaging recycling streams and has a renewable content higher than 50%. The adhesive dissolves completely in PET flake caustic wash recycling operations without clumps or “stickies.” They have also worked with the recycling industry and met standard protocol testing indicating the adhesive meets zero contamination in PET recycle streams.

• Henkel brings already established marketing, sales, formulating technology and distribution to the partnership. These were functions that DaniMer did not have as this was their first foray into the adhesives market with the introduction of their initial product offerings last year.
• Henkel, because of its prominence in the adhesive industry, has access to developments in complementary biobased formulating developments like tackifiers and waxes from its huge supplier base.
• DaniMer brings existing and planned manufacturing capacity, process technology and biochemistry necessary for biobased polymer development.
• Henkel’s marketing, industry knowledge and leverage cannot be underestimated. By having eager CPG customers who look at adhesives as one of the missing parts of their sustainability puzzle, this should open many doors for rapid adoption of biobased hot melt across a broad base of food and non-food brand owners.

Adhesives for hot melt PSA labels, side-seam PET bottle labels and folding cartons are the adhesives that actually are part of the consumer product package rather than the shipping container as is the case for corrugated closure adhesives. The ability for a CPG company to claim higher percents of bio-based materials for all product package components is a huge incentive to make this work. The joint announcements say the label adhesive was designed for PET container packaging with renewable content higher than 50%. The adhesive can dissolve completely in PET flake caustic wash recycling operations enabling zero contamination in PET recycle streams.

Although not a part of this partnership announcement the ability to control the technology through levels of exclusivity in the arrangement gives Henkel a potential opportunity to supply Avery Dennison and 3M their biobased requirements. This assures rapid growth if this technology proves viable for the stated applications. Almost all of the Avery Dennison and 3M’s PSA hot melt technology is captive and not currently available to Henkel or any merchant formulated adhesive supplier.

Also not mentioned in the partnership announcement is the whole area of tie layers for packaging multi-layer film structures. Most tie-layer adhesives are not ‘formulated’ by traditional hot melt formulators like Henkel, H. B. Fuller and Bostic. They are blends and compounds developed and marketed by the large polymer companies like Dupont Bynel®, Dow Primacor® and Rohm and Haas which are ‘applied’ via coextrusion rather than lamination. If these DaniMer biobased polymers have any utility in the tie layer segment this would be another huge market opportunity open to Henkel to create another market segment of business in an area not open to them or any merchant formulated adhesive manufacturer in the past.

Other biobased opportunities are developing for additional polymer families - acrylics, PE based tie layers (Dupont/Braskem), Polyamide (Arkema, Evonik, BASF, DuPont, DSM and Solvay) and polyurethane/ Other polymer suppliers offering some form of biobased products to the adhesive industry are – EcoSynthetix-biolatex, BioFormix-disubstituted vinyl monomers, Collano Adhesive AG - hot melt PSA polylactic acid or starch based polymers and Yparex- tie layers.

There are many more patented new technologies, first stage funding and start-ups who we will hear from in the not too distant future. The world of biochemistries cannot be ignored. It is incumbent on the adhesive industry to seek out and embrace these new technologies