Patent GB-1264432-A (GB)
IPC: C03C25/26
Filed: 1970-04-15
Abstract: 1,264,432. Coated glass filaments. HERCULES Inc. 15 April, 1970 [28 April, 1969; 7 Jan., 1970], No. 18065/70. Heading B2E. [Also in Divisions B5, B8 and D1] Glass fibres are coated with a thermoplastic polymer by applying the polymer at the spin bushing, in an integrated process with fibre spinning, substantially immediately following the fibre spinning, the polymer being applied as a dispersion of solid particles of less than 150 microns in any dimension in an inert liquid and thereafter heating to remove the inert liquid and fuse the polymer to a continuous matrix phase. The polymer may be nylon, polyethylene terephthalate, polyvinyl chloride, polyethylene, polypropylene, polystyrene, copolymers thereof. Water is the preferred inert liquid medium. A coupling agent may be dispersed with the polymer particles, the coupling agent having glass-reactive functional groups and the functional groups having an affinity for the matrix polymer, and being activated to couple to the glass during removal of the dispersing liquid and coupled to the polymer during the fusion step. The coupling agent may be a substituted silane, e.g. an azido or azodialkanoate substituted silane or a Werner complex. Alternatively, the coupling agents may be applied in a separate step for solution or dispersion prior to the addition of the polymer. Polyolefine coatings may be bonded to glass by sizing the glass with a silane having at least one acid-reactive functional group and incorporating a small amount of an acid modified polypropylene into the matrix polymer. Preferred acid reactive groups are hydroxyl, epoxy and amine groups. As shown in the figure a plurality of glass filaments 1 flow from spin bushing 2 and are taken up in spin package 3 whereby the filaments are subjected to draw-down and reduction in diameter. The individual filaments are drawn over coating roll 5 rotating in coating pan 4 containing a dispersion of the polymer. The coated filaments are then drawn over collecting device 6 into a yarn or roving and between radiant heaters 7. A small amount of a low molecular weight polymer, e.g. polyvinyl alcohol and polyvinyl acetate may be included in the polymer dispersion to serve as a temporary binder to maintain the integrity of the roving. Fusion of the coated and dried roving may be carried out as a separate operation. If fusion is effected prior to incorporation of the roving into a final shape, the polymer coated roving can be employed in glass filament winding operations and then fused to a continuous matrix enclosing all of the rovings, or reduced to small pellets useful as an injection moulding powder, in compression moulding, formed into woven or non-woven shÞets and subsequently heated to form reinforced mouldable sheets. The coated rovings can also be employed either as continuous filaments or as chopped filaments in centrifugal casting. They can also be shaped by pultrusion. In an Example an aqueous dispersion of polyethylene containing 2-chloro-3-[3-(trimethoxysilyl) propoxyl] propyl azidoformate is applied to glass filaments immediately upon formation at the spin bushing, and while still wet the filaments were wound on to a heated cylindrical mandrel to cause evaporation of the water and fusion of the polymer. The resulting tubular structure was removed from the mandrel and a section cut therefrom and moulded in a hydraulic press to form a reinforced sheet.