Patent GB-1134044-A (GB)
Title: Method for preparing a nonwoven fabric
IPC: D04H1/66
Filed: 1966-01-26
Abstract: 1,134,044. Laminated fabrics. JOHNSON & JOHNSON. 26 Jan., 1966 [29 Jan., 1965], No. 3484/66. Heading B5N. [Also in Division D1] A method for preparing a non-woven fabric comprises intermittently bonding together at least one first web comprising fibres substantially non-heat-shrinkable in the temperature range 350 to 400 F. and at least one second web comprising fibres substantially heatshrinkable in the temperature range 350 to 400 F. and having a fibre length greater than the space between adjacent bonded areas, and exposing the assembly, under controlled tension, to a temperature of from 350 to 400 F. for at least one second to ensure a shrinkage of within 2% of the total shrinkage possible, and to provide a heat-set fabric characterized by substantially uniform ripples of predetermined magnitude. As described the heat-shrinkable fibres are of, e.g. vinyl polymer, vinyl chloridevinyl acetate or vinyl chloride-vinylidene chloride copolymer, " Saran " (Registered Trade Mark), polyesters, polyolefines, such as polyethylenes and isotactic polypropylenes, acrylics, vinyl chloride/acrylonitrile copolymers; the non-heat-shrinkable fibres are, e.g. natural fibres such as cotton and linen; synthetic fibres such as fibres of regenerated cellulose, cellulose acetate or triacetate, polyamides, e.g. nylon, fluorocarbons, e.g. " Teflon " (Registered Trade Mark) or mineral fibres such as glass; and the fibre webs are bonded together by binders, e.g. regenerated cellulose, homo-polymers or copolymers of vinyl resins (examples of which are given in the Specification), acrylic resins (of which specific examples are given), butadiene resins (examples given), synthetic or natural rubber, urea resins (examples given), aldehyde resins (examples given), epoxy resins, cellulose derivatives (examples given), starches, gums or casein, the binders being applied as emulsions, solutions, dispersions, plastisols or powders. When the fibre webs are of suitable materials they are bonded by applying heat and/or pressure and/or solvents, and no binder is needed. When a binder is used it may be applied in geometrical patterns, or as spaced parallel or intersecting diagonal lines, or as continuous or discontinuous straight or curved lines, and is set by regenerating, curing, heating, or drying. The fibre webs may each be blends of fibres and must shrink at least 15% when heated to produce the desired ripples. In apparatus for carrying out the process of the invention, Figs. 1 and 2, a web 3 comprising heat-shrinkable fibres is sandwiched between webs 2, 4 comprising non-heat-shrinkable fibres and the webs are bonded by a binder applied by a roller 6 and set in a setting unit 9. The bonded webs 1 are then fed via tension rollers 21a, 21b to a heat source 23 where shrinking of the shrinkable fibres occurs, the web then being fed to tension rollers 24a, 24b before being wound up on a roll 25. The tension rollers 21a, 21b have a greater peripheral velocity than the rollers 24a, 24b so that shrinkage of the web is allowed, the amount of shrinkage being controlled by the difference in the peripheral velocities of these rollers. The heat source 23 may be an oven, heated rolls or infra-red heaters. To improve shrinking a moisture content of 15-20% by weight may be applied to the web either from a source of moisture 26, or by using steam as the heat source. In the embodiment shown three webs are used but more are possible, in which case rippling may take place in two opposed directions in the interior of the fabric. Ripples may be produced on one or both surfaces and may be staggered on opposite faces. The completed fabric may be used as packaging material, curtains and draperies, quilting or padding, dress shields, battery separators, surgical articles, and cleaning materials.