| 摘要 |
<p>A transparent sheet consists essentially of (1) square woven glass cloth coated and impregnated with (2) a cured methylphenylpolysiloxane resin having a composition consisting essentially of from 45 to 55% by weight of phenyl radicals calculated on the total weight of the resin, a ratio of phenyl radicals to silicon atoms of from 0.70/1 to 0.85/1, a ratio of phenyl radicals to alkyl radicals of from 0.90/1 to 1.15/1, and a ratio of total hydrocarbon substituents to silicon ratio of from 1.45/1 to 1.55/1, any hydrocarbon radicals in said resin other than phenyl and methyl being essentially ethyl groups in the form of monoethylsiloxane units in amounts up to 15 mol per cent. of the total siloxane units in said resin, said transparent sheet being of such a degree of flexibility that it has a droop angle of at least 20 DEG at 25 DEG C, and not greater than 75 DEG at 100 DEG C. The thickness of the coating should be somewhat greater than that of the glass cloth. The siloxane units may be monomethyl-, dimethyl-, phenylmethyl-, monophenyl-, and diphenylsiloxane units. The glass cloth may be dipped into a solution of the catalysed resin in an organic solvent, passed through coating rollers and a heated curing tower. Two coatings are generally necessary.</p> |
