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A Formaldehyde‐Free Water‐Resistant Soy Flour‐Based Adhesive for Plywood
Author(s) -
Damodaran Srinivasan,
Zhu Dan
Publication year - 2016
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-016-2866-x
Subject(s) - adhesive , soy flour , hardwood , water resistance , formaldehyde , veneer , pulp and paper industry , urea formaldehyde , materials science , composite material , chemistry , food science , organic chemistry , botany , layer (electronics) , engineering , biology
The phasing out of the use of urea–formaldehyde adhesive in the fabrication of interior‐used hardwood plywood requires development of environmentally friendly bio‐based wood adhesives. We recently reported that phosphorylation of soy flour (SF) using phosphoryl chloride (POCl 3 ) greatly improved the moisture resistance of soy flour adhesive. In the present study, we investigated the effects of inorganic oxidizing agents, such as NaClO 2 and Ca(NO 2 ) 2 , to further improve the wet bonding strength of phosphorylated SF (PSF) wood adhesive. We report that addition of 1.8 % (wet weight basis) Ca(NO 2 ) 2 to phosphorylated SF (PSF) adhesive formulation containing 25 % soy flour solids increased the wet bonding strength to greater than 3 MPa at 140 °C hot‐press temperature. The water resistance testing of the glued three‐ply hardwood plywood panels passed the three‐cycle soak/dry test recommended by the American National Standard for Hardwood and Decorative Plywood/Hardwood Plywood and Veneer Association protocol (ANSI/HPVA HP‐1‐2004). Since the process involves only inorganic chemistry and no petroleum‐based chemicals such as formaldehyde or polyamidoamine–epichlorohydrin are used, the PSF + Ca(NO 2 ) 2 adhesive is non‐toxic and environmentally safe.