| 摘要 |
1473882 Laminated non-woven web JOHNSON & JOHNSON 8 July 1974 [9 July 1973] 30095/74 Heading B5N [Also in Division D1] A non-woven web comprises two juxtaposed through-bonded layers, one layer (a) comprising a mixture of short and long fibres (i.e. less and greater than “ inch), the two faces containing respectively an excess of long and short fibres over the total concentration thereof in the web and there being a continuous gradual transition of fibre concentrations between said faces, and the other layer, (b) being bonded to the face of layer (a) containing an excess of short fibres and having at its outer face a greater concentration of long fibres than is present at the inner "short-fibre" face of layer (a). The long fibres may be textile-length rayon, polyester, cellulose acetate, nylon or polyvinyl alcohol, and the short fibres may be wood pulp or cotton linters for papermaking. The layer (a) may comprise 25% long fibres and 75% short fibres, rising to 32À5% and 82À5% at the enriched faces. Layer (b) may (1) be identical to layer (a), with the layers bonded in mirror relationship; or (2) may comprise (i) a uniform blend of long and short fibres, (ii) separate strata of long and short fibres, or (iii) as (ii) but with an intermediate stratum of blended long and short fibres; or (3) may be entirely of long fibres. Layers of type (2) may be produced on an apparatus in which separate fibre streams are fed to a common duct, the degree of intermixing being controlled by a baffle (see Specification 1,375,585). The outer face of layer (b) may be reinforced by woven fabric or plastics sheets. Where layers (a) and (b) are identical, the short-fibre enriched face may be moistened and compacted to provide a paper-like densified surface; two such layers may be bonded with these faces in contact. The layers (a) and (b) may be of the same or different thickness; in the latter case the thinner layer should comprise at least 20% of the total thickness. As shown (see also Specification 1,375,585), identical webs (a) and (b) are formed from short fibre masses 22 and long fibres 23 which are opened and mixed by rotating lickerins 24, 25 feeding individual fibres into gas streams. The gas streams intersect, whereby the fibres are deposited over different portions of a foraminous belt 27, with the aid of suction 35. The layers are combined at 29 and bonded at 31, with the aid of suction at 33, by a selfcross-linking acrylic emulsion which may contain a surfactant. Alternatively, the bonding agent may be separately applied to each layer before combination. The combined web is dried throughout, to prevent migration of binder, by dielectric, infrared or air flow heating at 41 and on the surfaces by steam cans 42, 43. If the binder is allowed to concentrate at the surfaces, a delaminatable web may be formed. In modifications, the two belts may move in the same direction, one layer being removed for combining (thus varying the shingling of the fibres), or the second layer may be deposited directly on the first. |
