Abstract
The purpose of this investigation is to improve the toughness, water-proof, and electrical insulation of phenolic resin. For this purpose, distance between two crosslinking nodes of phenolic resin was made longer and density of phenolic OH group was made lower. In the concrete, glutaraldehyde was used instead of formaldehyde. At first, reaction condition such as the kind of solvent or catalyst was investigated in order to synthesize novolac type phenol-glutaraldehyde resin. As a result, the reaction was easily proceeded when acetic acid and HCI were used as solvent and catalysis respectively. Next, flowability and curing behavior of molding compounds which were prepared from phenol novolac, the phenol-glutaraldehyde resin, hexamethylenetetramine as curing agent, and wood flour as filler were investigated. As a result, when the content of the phenol-glutaraldehyde resin was less than 60wt%, the molding compounds were suitable for transfer molding. Curing rate was not depended on the content of the phenol-glutaraldehyde resin. Properties of cured resin by transfer molding from the molding compounds were also investigated. It was found that toughness, water-proof, and electrical insulation were improved by an increase of the content of phenol-glutaraldehyde resin.
