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Modification of diisocyanate-based particleboard and plywood glues with natural polymers. Polyphenols, carbohydrates, and proteins. Chapter 17

: Dix, B.; Marutzky, R.

American Chemical Society -ACS-, Washington/D.C.:
Adhesives from renewable resources
Washington/D.C., 1989 (ACS Symposium Series 385)
ISBN: 0-8412-1562-6
S.229-241 : Tab.,Lit.
American Chemical Society (Meeting) <194, 1987, New Orleans/La.>
Fraunhofer WKI ()
Diisocyanat-Klebstoff; polyphenol; protein; Spanplatte; Sperrholz; Stärke; Streckmittel

Investigations aimed at finding some fast-setting glues for exterior plywood and particleboard based on diisocyanates in combination with compounds from renewable resources like tannins, proteins, and starches revelaed the following: The mechanical properties of particleboard bonded with unmodified tannin extracts from spruce (Picea abies) and pine (Pinus sylvestris) were inferior. The fortification of the tannin extracts with diisocyanate increased the bonding strength and reduced the thickness swelling. With one exception, particleboards bonded with nonemulsifiable diisocyanate modfied with glutin or maize starch (extender content up to 20 %) had exteriorgrade quality (German standard V100 for flat-pressed boards). Veneer plywood, which is conditionally weatherproof (German standard AW), can be produced by applying diisocyanate together with tannins or starches. The veneer wood species, the glue mixtures, the pressing conditions, and the fillers have to be adjusted to the diisocyanat e type and the extender. Modified, emulsifiable diisocyanate gave plywood with better strength and wood failure than glue formulations with nonemulsifiable diisocyanate