High voltage plastics insulator with moulded laurolactam body - decomposing in air at high temp. without melting

摘要

High voltage plastics insulator has an insulating body of a laurolactam ("Hardomid" RIM) moulding, which does not melt on heating but decomposes in air at ca.217-271 deg.C and can no longer be regenerated and has a metallic ring. The moulding has a following properties: tensile stress 470-520 kp/sq.cm (DIN 53455), EB 17-25% (DIN 53455), tensile strength 500-630 kp/sq. cm (ISO R 527), EB 200-350% (ISO R 527), elastic modulus 19 000-22000 kp/sq.cm (DIN 53457; clause 2.3), flexural strength 750-1000 kg/sq.cm (ISO R 178), notch impact strength 55-65 kpcm/sq.cm (DIN 53453), 10" ball pressure hardness 1000-1050 kp/sq.cm (DIN 53456, stage C), abrasion resistance 158- 129 mm3/rpm (on Taber abrader), creep under tension 50-60 kp/ sq.cm (DIN 53444- 23 deg. C/95% RH) and creep modulus 13000-14000 kp/sq.cm (DIN 53444). The body and/or pts. are made by melting the lactam monomer with exlusion of O2 and water adding 0.01-5 wt.% catalyst(s) and then 0.01-5 wt.% activator(s) to the melt at constant temp. and transferring the fluid mixt. to the mould within 1 min. and polymerising it. Alternatively, the moulding can be milled or cut and extruded ("Dohamide"; RTM). The moulding can have metal end caps and inserted insulating discs. The insulator has greatly improved insulating properties, is not sensitive to moisture or dirt, is equal to high mechanical flexural stresses and is not destroyed by electric overloading.