Research On The Ultra-low Formaldehyde Releasing Particleboards

According to the standard of ultra-low formaldehyde releasing particleboardsput forward by the California air resources board, this paper used the newtechnology of surface paring using UF and core paring using MDI, systematicallystudied the ultra-low formaldehyde releasing particleboards. This paper mainlystudied: physical and chemical properties of the adhesive, selecting a suitable rangeof moisture content, determining the appropriate process conditions, furtherresearching to reduce the ratio of the core wood shavings which reduced the MDI toreduce cost, achieving a win-win of performance and cost. The main results were asfollows:(1) MDI performanced characteristics of the thermoplastic resin when theyseparately existing, endothermic and exothermic reaction couldn't occur below200℃. Curing reaction of MDI mixed with water heating could occur, accompaniedby the phenomenon of the endothermic and exothermic.(2) The moisture content of wood shavings was very significantly to theformaldehyde emission of the board. With the moisture content increasing,theformaldehyde emission was logarithmically increasing. The moisture contentbetween6%and8%, we can get better physical and mechanical properties andformaldehyde emission of the plate.(3) The ideal processing parameters: resin content of UF:8%, thehot-processing temperature:165℃,the hot-pressing time:45s/mm.(4) The core quality of wood shavings was significantly to the formaldehydeemission of the board. With the table core quality of wood shavings reducing, theformaldehyde emission of the board decreased.(5) With the resin content of UF increasing, the formaldehyde emission of theboard decreased. The resin content of UF was significantly to MOR(6) With the hot-pressing temperature increasing, the formaldehyde emission ofthe board decreased and then increased. The hot-pressing temperature wassignificantly to MOR and MOE.(7) With the hot-pressing time increased, he formaldehyde emission of theboard decreased.(8) We can meet the requirements of ultra-low formaldehyde emission particleboard put forward by the CARB.(9) The particleboard pressed by10%MDI-90%UF can save61.3%more thanthe particleboard pressed by100%MDI.