低密度厚型纤维板喷蒸热压工艺

采用正交试验方案,用喷蒸热压法压制低密度厚型纤维板,并对产品进行性能检测,通过数据处理和分析,结果表明:①静曲强度——随施胶量和喷蒸时间的增加而提高,且施胶量较小或喷蒸时间较短时其影响较大;随热压温度的提高而明显下降;热压时间对其影响很小。②弹性模量——随热压时间的增加而下降,且热压温度越高影响越明显;随施胶量、热压时间及喷蒸时间的增加而增大,施胶量的影响明显,而喷蒸时间的影响较小。③吸水厚度膨胀率(24h)——随热压温度的提高而明显增大;随喷蒸时间和施胶量的增加而减小,且喷蒸时间较长或施胶量较大时其影响较大;随热压时间的增加而稍有增大。④出板含水率——受热压时间的影响较大,随热压时间的增加而明显下降;随热压温度的降低、或喷蒸时间和施胶量的增加而增大,但其影响都较小。⑤在板坯含水率8%、蒸汽压力0.35MPa条件下使用脲醛树脂胶黏剂压制厚度50mm、密度0.3g/cm3纤维板的适宜喷蒸热压工艺为:热压温度175℃、施胶量8%、喷蒸时间10s、热压时间8s/mm。

Steam-injection Pressing Technology of Low-density Thick Fiberboard

An experiment was conducted to produce the low-density thick fiberboard pressed by steam-injection hot pressing by orthogonal experiment.The performances of the board were checked.Results show that modulus of rupture(MOR)enhances with increasing resin content and prolonging of steam injection time,and the change is less under lower resin content and injection for a shorter time.MOR reduces obviously with hot-pressing temperature increasing,and pressing time has little effect on MOR.MOE decreases with the prolonging of hot-pressing time and higher temperature has a more obvious effect on the MOE.MOE increases with the increase of resin content,hot-pressing time and steam injection time,and resin content affects MOE more evidently,while the steam injection time has little effect on the MOE.Thickness swelling rate(24 h)increases obviously with temperature elevation and decreases with the increase of steam injection time and resin content,and the influence is more significant under higher resin content and longer steam injection time.Thickness swelling rate increases slightly with the hot-pressing time prolonging.The hot-pressing time affects moisture content of board more obviously,and moisture content decreases evidently with the hot-pressing time prolonging.The moisture content heightens with the temperature decreasing and steam injection time,resin content increasing,but the influence is slight.The optimal technology for producing fiberboards with thickness of 50 mm,density of 0.3 g/cm3 under mat moisture content of 8%,steam pressure of 0.35 MPa using UF as adhesive were obtained as hot-pressing temperature 175 degrees C,resin content 8%,steam injection time 10 seconds,and the hot-pressing time 8 seconds per millimeters.