| 摘要 |
The surface layer of organic fibres has a wt. of 10-40 g/m2, pref. 25 g/m2, impregnated with water glass, and is firstly joined to a thin plastic layer, which in turn is fixed by heat to the main mineral wool structure of the shell. The main part of the surface layer is composed of cellulose fibres, which are mixed with rayon fibres, possibley even polyester fibres. The water glass is of the prepolymerised type, e.g. EKA Bindzil FA 7216 (RTM). - The plastic layer has a surface wt. of 5-20 g/m2, pref. 10-15 g/m2., and is of polyethene. When the pipe sheet is made, it is slit into two halves, and then the surface layer is applied. The surface layer is then heated so that the plastic layer softens and remains adhesive. It is then cooled so that the plastic layer hardens. The surface layer has overlapping parts along the slit, or along one end edge, or along both, and such parts are not heated. |
