Phenolic resin glue

A resin obtained by polycondensation of phenols (mainly phenol, resorcin, cresol) with formaldehyde. The main use in wood processing is thermosetting phenolic resin. The properties of the resulting resin vary depending on the catalyst. If ammonium hydroxide is used as a catalyst, an alcohol-soluble resin can be obtained, which is mainly used for impregnating kraft paper as a film; if sodium hydroxide is used as a catalyst, it is made into a water-soluble resin; The molecular weight of the resin is also different.

The reaction temperature and reaction time also have an effect on the properties of the resin. The phenolic resin glue has good boiling water resistance and weather resistance, and its products belong to a class of high water resistance outdoor type, which are used for aircraft, ships and building components. It is mainly used for hot pressing (temperature 125-150 ° C), and the pressing time is longer than that of urea-formaldehyde resin. However, the pressing time can be shortened by adding resorcin or saponin or adding some blood powder and improving the preparation process.

For example, polycondensation under alkaline conditions and then polycondensation under acidic conditions yields a high molecular weight resin, which is insoluble in water, and can be made into an emulsion by adding a natural resin or polyvinyl alcohol. Phenolic resins are also widely used for impregnating kraft paper for the bottom layer of decorative panels. In order to make the impregnated paper tough, it is generally copolycondensed with cresol or xylenol with phenol and formaldehyde. Resorcinol formaldehyde resin can be cured at neutral and room temperature. It is best to withstand boiling water and weather resistance by cold pressing. It has a simple adhesive process and is used for thick wood or board such as bridges, sleepers and outdoor. Components. After the amino resin and the phenolic resin are cured, the rubber layer shrinks and is brittle. The addition of the extender or the filler makes the rubber layer have a certain plasticity, and the aging resistance can be improved.