| 摘要 |
<p>A prod. for use in electrical construction is based on a complex of glass fibres and a phenolic resin. The complex consists of a mat of short glass fibres of density 300-600 g./m2 and a glass fibre roving of equiv. wt., the two being bound together by stitching with the aid of glass filament. The prods. are used esp. in electric insulators. Insulating prods. obtd. from glass fibre and thermosetting resins, e.g. epoxy and polyester resins have bending resistance is not >20 daN/mm2 and tensile strength is not 25 daN/mm2. The equiv. figures for the prods. obtd. by the present method are is not >45 and is not >40, respectively. The glass fibre complex is impregnated with a soln. of phenolic resin, cut into sheets and then a pile of sheets is cured under pressure. Pref. impregnation is by coating, followed by drying at, e.g., 110-130 degrees C at a rate of passage of 3.5m/min. Curing is effected at 140-165 degrees C under 20-40 kg./cm2 pressure.</p> |
