| 摘要 |
A method for the production of moulded articles having a width dimension greater than their thickness, e.g. building panels and doors, comprises charging into a mould a foamable composition containing a phenol-formaldehyde resin, an acid catalyst and a filler having a neutralising effect, causing the composition to expand to fill the mould and the resin to cure, and thereafter removing the moulded article from the mould, wherein the mould cavity has a depth substantially equal to the width of the resulting moulded article and a width substantially equal to the thickness of the resulting moulded article, the temperature of the mould surface at the commencement of charging of the foamable composition is in the range of 60 to 90 DEG C, the temperature of the foamable composition during curing is at least 90 DEG C, and the pH of the final cured foam is not less than 2. The neutralising effect filler is preferably aluminium hydroxide, which allows the pH of the curing/foaming reaction to rise to 2 to 4. The resin may be glycol-modified. |
