Panel products, diisocyanate adhesive

Formulations for particleboard and plywood adhesives based on combinations of diisocyanates and compounds from renewable resources like tannins, starch, and proteins have been developed and tested at the Fraunhofer-Institute. All in all, the results of gluing tests indicated the potential for using diisocyanates combined with natural polymers for adhesive purposes where each natural product used alone will fail. More attempts will be necessary to find precise mixtures to produce successful adhesives for panel products. The development of adequate particleboard and plywood glue formulations based on diisocyanates and natural polymers has to be accompanied by more sophisticated technologies than those used in conventional production processes. The results presented here may give some hints on how these technologies can evolve. 

Adhesives based on isocyanate (especially PMDl, polymethylene diisocyanate, more exactly polymeric 4,4 -diphenylmethane diisocyanate) have been used for more than 25 years in the wood-based panel industry [88], but still have a low market value in the wood-working industry compared to systems based on UF-, MUF- or PF-resins. The main application is the production of waterproof panels, but also the production of panels from raw materials that are difficult to glue, like straw, bagasse, rice shells or sugar cane bagasse. They can be used as adhesives for wood-based products like particleboard, oriented strandboard (OSB), laminated strand lumber (LSL), medium-density fiberboard (MDF) or... 

Adhesives from Diisocyanates and Proteins. Protein-based adhesives have been used as traditional binders for wood since the beginning of wood products manufacture. Glutin and casein binders can provide interior-grade wood products but with modified casein binders, even panels for exterior use are possible. For economic and technical reasons, protein-based wood adhesives have been replaced more and more by synthetic adhesives since the beginning of the century. 

A double-side adhesive tape was prepared using a mixture of a hydroxylterminated poly butadiene, a polyol, and an isocyanate compound containing an oxadiazinetrione ring 241 A compound suitable for sealing spaced glass panels comprises a reaction product of an unsaturated polymer with functional end groups with HTPB, a decane thiol adduct, and tolylene diisocyanate 242). 

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