Non-stick coatings for paper, films or fabric - comprising vinyl terminated linear polysiloxane, vinyl siloxane cross linker and catalyst

摘要

Compsns. for coating of paper, film or fabric comprise: (a) 4 pts. wt. of a vinyl-end-stopped linear polyorganosiloxane of viscosity up to 500 cP; (b) 0.5-1.5 pts. wt. of a crosslinking agent contg. Si-vinyl and SiH-units; (c) a diaziridine; and (d) a Pt complex. Component (b) consists of molecules having =10 Si atoms linked together by O atoms. The 2 reactive gps. lie adjacently in the same mol. and the residual Si valencies are attached to Me gps. The siH gps. are present in a proportion of from 1:1 to 2.5:1 in relation to the total amt. of Si-vinyl units in the mixt. The amt. of metal in (d) is up to 0.01 pt. wt. based on 100 pts. wt. of the mixt. and the amt. of (c) is 75-250 times the amt. (d). Used for prepn. of papers, foils, fabric belts, etc having a non-adherent surface film (to which adhesives do not stick). Fully satisfactory films can be applied without use of solvents. In an example, a mixt. of 970 g vinyl end-stopped poly Me-siloxane, 1.8g. Me-Et-diaziridine and 2 ml Pt complex (contg. 25.6 mg Pt) was stirred with 240 g of a crosslinker of formula H.SiMe2.O.X5.5Y2.2 SiMe2H where X = SiHMeO-and Y=Si(CH:CH2) MeO. Applied by doctor to Kraft paper it gave a satisfactory film on curing for 20s at 150 degrees C.