| 摘要 |
988, 354. Bonded fibrous sheets. GUSTIN-BACON MANUFACTURING CO. March 25, 1964 [April 1, 1963], No. 12652/64. Heading D1R. A bonded fibrous sheet material having at least one of its surfaces compressed to a greater density than the interior of the sheet is prepared by compressing and heating a mat comprising fibres and a heat curable binder so that at least one face is cured to a limited depth, allowing the mat to spring back to a greater thickness and heating the mat to complete the curing of the binder at the desired thickness of the final product. A loose mat 16 of glass fibres together with a thermosetting resin, such as phenol formaldehyde,is deposited upon a foraminous belt 12 and is compressed and heated by means of rollers 18, 19 at least one of which is heated. The heat supply is only sufficient to cure the surface or surfaces to a limited depth and the mat springs back to a greater thickness after passage through the nip. The mat then passes through a final curing oven 23 in which opposed belts 24, 25 confine the mat to the desired final thickness. The cured mat passes to a conveyer 32 for the finishing operations such as slitting or painting to be carried out. In modified apparatus (Figs. 2 and 3 not shown), opposed belts are used to provide the initial compression stage and means are provided to cause a partial precuring of the mat before the first compression stage. Additional bonding agent may then be sprayed on the partially precured mat. |
