| 摘要 |
Method uses a web impregnated with curable resin and expandable thermoplastic microspheres in a solvent carrier. The impregnated web is overlaid by a porous material and is hot pressed which causes curing, microsphere expansion, and solvent removal to take place simultaneously. The solvent escapes by passing through the porous material. Web is pref. of glass fibre or polyester fibre. The web is conventionally impregnated with a mixture consisting of unexpanded microspheres of any suitable thermoplastic, dispersed in a soln. of a curable resin, such as phenolic resin in aqueous soln. of 50% solids. Microsphere content is pref. such as to form 75-90% by volume of the finished composite. A sheet of porous material is placed over one or both sides of the impregnated web and the assembly is placed in a hot press, typically at 140 deg.C. The porous material allows solvent emission during pressing and allows partial penetration by the resin mixture. Suitable porous materials include expanded metal, foamed plastics pref. with a density of 5-80 kg/cm3, and glass or mineral wood pref. with a density of 100-200 kg/cm3. |
