| 摘要 |
PURPOSE:To prevent air bubbles from mixing in a prepreg by a method wherein the raw threads of base material are opened by being converted their running directions in such a manner that the base material is passed through pairs of parallel opening rollers, the axis line of each pair of which obliquely intersects the longer direction of the base material. CONSTITUTION:An opening device 4 consists of two pairs of parallel opening rollers 5, 6 and 7, 8. The angle theta1, between the axis line of the opening rollers 5 and 6 and the feeding direction of a glass cloth A and the angle theta2 between the axis line of the other opening rollers 7 and 8 and the feeding direction of the glass cloth A are controlled to be equal to each other. By being passed through the opening device 4, the wefts of the glass cloth are untwisted by the opening action developed by being twistedly passed through the rollers 5 and 6 and 7 and 8. The resultant opened glass cloth A is successively immersed in an impregnating tank 9 in order to be impregnated with varnish and, after being passed through thickness adjusting slit bars 10, introduced in a drier 11 so as to be heated to obtain a prepreg. No bubble is recognized in the prepreg. In addition, no bubble is also recognized in a laminated sheet of the prepregs. |
