Synthesis and Properties of Aldehyde-free Water-based Hot Melt Adhesive for Plywood
Polyurethane prepolymers were synthesized with toluene diisocyanate(TDI),isophorone diisocyanate(IPDI),poly1,4-butanediol adipate(PBA),polypropylene oxide ether triol(PPO)as main monomers,sodium ethylenediamine ethanesulfonate(AAS-Na)as sulfonic acid monomer,and 1,4-butanediol as chain extender.The water-based hot melt adhesive for plywood was prepared by emulsifying ethylene-acrylic acid(EAA)aqueous emulsion and modifying Polymethylene phenyl isocyanate(PMDI).By studying the different isocyanate root index(R value),AAS-Na content,PPO content,EAA emulsion addition ratio and PMDI dosage of adhesives,it was determined that when R value was 1.2,AAS-Na accounted for 3%of prepolymer mass fraction,PPO accounted for 3%of prepolymer mass fraction,and EAA emulsion addition ratio was 30%.When PMDI was added to 10%,the adhesive had the better comprehensive performance,and the plywood prepared with this adhesive met the requirements of Class I plywood in GB/T 9846-2015 Plywood for general use,and the formaldehyde emission was 0.012 mg/m3 which met the requirements of ENF level.
plywoodwater-based hot melt adhesiveEAA aqueous emulsionENF levelClass I plywood
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