ObjectiveThe low density fiberboard (LDF) has advantages of light weight, sound absorption and noise reduction, and can be widely used in the fields of furniture manufacturing materials, building decoration materials, packaging materials, electrical equipment materials, etc. Compared with medium density fiberboard, low density fiberboard has disadvantages of poor mechanical properties. Low density fiberboard prepared by melamine resin adhesive, phenolic resin adhesive or urea-formaldehyde resin adhesive is difficult to meet the requirement of the mechanical properties, and its formaldehyde emission is difficult to reach the E₁ standard. Therefore, MDI low-density fiberboard with low density and excellent performance is prepared using isocyanate (MDI) with high bonding strength and formaldehyde-free release as adhesive.

MethodIn this study, fiber moisture content, fine fiber ratio and hot pressing curve were taken as process parameters to analyze the influence of various parameters on physical and mechanical properties of LDF, and the optimal preparation process of MDI low density fiberboard was developed.

ResultThe results showed that increasing moisture content of fiber and prolonging low-pressure time can increase density ratio of surface layer to core layer, thereby increase MOR and MOE, but IB was slightly decreased; increasing the mass fraction of coarse fiber can improve MOR and MOE effectively, while IB was decreased, TS also increased slightly. The preferred preparation process of MDI low-density fiberboard obtained in this study was: 16% fiber moisture content, hot-press curve C, 60% fine fiber. Through measurement of the thermal insulation coefficient and formaldehyde emission, it was found that MDI low density fiberboard had a better thermal insulation performance than the same density thermal insulation materials, and formaldehyde emission was low.

ConclusionMDI low density fiberboard prepared in the study can meet the requirement for furniture LDF under dry condition of Low density fiberboard and ultra-low density fiberboard. So it can be used widely in furniture making and building insulation materials.