Vorwiegend aus synthetischen Fasern bestehendes, endloses Unterlageband für die Herstellung von Flächengebilden und Verfahren zu dessen Herstellung

摘要

An endless woven fabric, suitable for use as a paper machine felt, manufactured at least predominantly of synthetic fibres in which adjacent fibres are bonded together at their mutual points of contact are made by treating an endless woven fabric after weaving with an aqueous solution of an inorganic salt, which, in the form, of a substantially saturated aqueous solution has a swelling and solvent, or near solvent, action on at least some of the synthetic fibres, to cause bonding together of adjacent fibres at their mutual points of contact and then washing to remove the inorganic salt. The endless woven fabric may be a fabric which is woven endless or a fabric which is woven as a length and the ends then joined. If the fabric is made wholly or predominantly of nylon and/or acrylic fibres the inorganic salt used may be calcium or lithium bromide or calcium or magnesium thiocyanate and if the fabric is made wholly of polyester fibres or contains a predominant proportion of polyester fibres in addition to nylon and/or acrylic fibres the inorganic salt used may be calcium or magnesium thiocyanate. The concentration of the inorganic salt in the aqueous impregnating liquor may be 0.5-10% by weight. After impregnation of the fabric with the aqueous solution of the inorganic salt the water may be evaporated from the fabric so that the salt solution concentrates and becomes localised preferentially at the cross-over points of the fibres causing small portions of the fibre surfaces at the cross-over points to gelatinise so that on complete evaporation of the water the fibres become bonded with adjacent fibres. The fabric may then be washed free of inorganic salt and dried. The warp yarns of the fabric may be spun from crimped synthetic fibres, straight synthetic staple fibres or may be continuous filament synthetic yarns, continuous filament bulked synthetic yarns of the non-stretch type, or yarns composed of a core of continuous filament synthetic yarns around which is wrapped a finer bulked synthetic yarn of the non stretch type and the weft yarns are preferably spun from synthetic staple fibres which may be the commercially-produced crimped synthetic fibres or may be prepared by cutting continuous filament "bulked yarns", "stretch yarns" and "bulked and stretch yarns" into staple fibres. One or both surfaces of the endless woven fabric may be raised before impregnation with the inorganic salt solution or the fibres of the fabric may be bonded by impregnation, evaporation of entrained water and re-washing and one or both surfaces raised. To improve the bonding during the drying process following impregnation, the fabric may be pressed to the heated cylinder of the felt-stretching machine on which it is dried by means of a relatively heavy roller.