Carbon Resistance Strip: Carbon and Phenolic Resin in Ethyl Acetate, Cured on Semi-Cured Phenolic Sheet

Podolsky (Wirt Company, US 2,060,114, 1936) bonded the carbon film into its base: the phenolic sheet is only half cured, the coating carries the same kind of resin, and its solvent (ethyl acetate) softens the sheet's surface. Heated calender rolls then finish the cure of sheet and coating together, so the track is hard, does not rub off and lasts. Cut across, the sheet gives resistance strips for a variable resistor. The picture: our diagram.

중급

1 day

안내

Mix 21 carbon, 26 resin, 53 solvent

Make a solution of 21 % carbon, 26 % phenol-formaldehyde resin and 53 % ethyl acetate. The patent says the exact proportions are not essential; this is its example.

이 단계의 재료:

탄소21 parts

액상 베이클라이트 (페놀-포름알데히드 축합 생성물)26 parts

필요한 도구:

아세트산에틸

접시 저울

유리 비커

젓는 도구

전면형 호흡보호구

고무장갑

Coat the semi-cured sheet

Use a phenolic sheet whose cure was stopped before it fully hardened. A roller turning in a pan of the solution coats its underside.

이 단계의 재료:

반경화 페놀 시트1 개

필요한 도구:

침지 코팅 롤러 쌍

전면형 호흡보호구

고무장갑

Cure between calender rolls at 350 °F

Pass the coated sheet between calender rolls heated to about 350 °F (177 °C). This finishes the cure and bonds the coating to the sheet. The patent sometimes calenders it again to burnish the surface.

필요한 도구: