| 摘要 |
<p>PURPOSE:To form a laminated sheet that contains volatile matters less and is excellent in the insulating properties and resistance to heat by a method of forming a laminated sheet by heating and pressing laminated prepregs, in which method after the curing, the product is allowed to stand at high temperatures under no load. CONSTITUTION:For example, a plurality of prepregs of kraft paper impregnated with a phenol resin are laminated, and are heated and pressed at a temperature of about 170 deg.C and a pressure of about 140kg/cm<2>, and after the completion of curing of the resin, while the laminated sheet is still at high temperatures, the pressure is relirveed, and then it is allowed to cool. During this period the volatile constitutents remained in the laminated sheet can evaporate to be removed. In a case cavities occur in the prepreg due to destruction of bonding between the layers when the volatile constituents evaporate, the prepreg will be restored by pressing it again at high temperatures after the relief of the first pressing.</p> |
