| 摘要 |
<p>1,220,266. Moulding composition. MONSANTO CO. 5 June, 1968 [5 Sept., 1967], No. 26750/68. Heading C3B. A moulding composition in grain form is made by stirring into an aqueous slurry of fibres a thermosetting resin and a curing agent therefor at a temperature at which the resin is liquid, continuing stirring until the resin reaches the "B"-stage, rapidly cooling, removing the water, and drying the residue. A predominant number of the grains comprise parallel reinforcing fibres bonded by thermosettable resin to form an integral unit and a film of resin is bonded to and completely envelopes the unit. The fibres are of length 30 Ám-1 inch, with length/diameter ratio of from 20 to 1000. The resin may be an "A"-stage epoxy, polyester, phenolic, amine, amide, or urethane resin; epoxy resin is specified in all the examples. The fibres may be of glass, B, SiC, silicon nitride, C, graphite, Nb, Ta, Hf, W, Mo, bronze, Cu, Pb, Be, Ag, stainless steel, SiO 2 , Al 2 O 3 , sapphire, ZrO 2 , TiO 2 , asbestos, hemp, bamboo, Al 2 O 3 /SiO 2 , potassium titanate, nylon, polyacrylonitrile, polypropylene, or polyester, or mixtures thereof. The fibre slurry may be formed in water containing a surfactant, preferably cationic or non-ionic. Also present may be 0-40% by volume, based on fibre+ filler, of fine filler as a collimating aid, e.g. clay, talcum, lampblack, rutile, SiO 2 , SiC, or crushed glass wool, asbestos, or fibrous clay; or electrical conductors or insulators, thermal insulators, or radiation shielding materials, e.g. Pb powder, may be used. The mixing may be performed by separately warming slurry and resin, e.g. to 50-100‹ C., and stirring the resin into the slurry. The curing agent may be added to the mixture or to the resin just before mixing with the slurry. A coupling agent may be added to the slurry before the resin and curing agent. The dried granules may be compression or transfer moulded. They may first be extruded through a constricted channel to obtain a pre-preg strand having oriented fibres; this extrusion is conducted at a temperature low enough to prevent conversion to the C-stage; e.g. 100-150‹ C.</p> |
