Patent GB-1087321-A (GB)
Title: Crimped synthetic linear polyester fibres
Inventor: KNAPP PETER EDWIN
IPC: D01F6/62
Filed: 1964-02-05
Abstract: 1,087,321. Making crimped polyester fibres. IMPERIAL CHEMICAL INDUSTRIES Ltd. Jan. 28, 1965 [Feb. 5, 1964], No. 4880/64. Heading B5B. Crimped polyester fibres having a tenacity of 2 to 6 gm./den., an extension to break of 15 to 60%, an initial modulus of 25-40 gm./den., a crimp index of 15 to 70%, a crimp level of 2 to 13 crimps per straight inch, a mean rate of change of instantaneous modulus, between 5 and 10% extension, of 90-160 gm./den., a denier of 1-6 and an asymmetry of refractive index of not less than 1À10<SP>-3</SP> measured across the width of the fibre, are made by melt spinning a synthetic linear polyester and quenching a bundle of hot filaments thereby formed asymmetrically during their travel from the spinneret to a winding device in which quenching step they come into contact with a continuously renewed thin film of a liquid on the surface of a solid body and in which said liquid is at a temperature considerably below that of the filaments, in a manner such that the filaments first contact said quenching liquid at a distance between 4 and 14 inches below the spinneret, drawing the filaments in the form of a tow in a liquid or in steam, followed by heat setting and cutting the tow into fibres. The as-spun filaments may be combined into a tow, e.g. of 600,000 denier and drawn in steam at 2-0 to 4-0 times their original length. If desired, a water drawing process may be used and in this case a draw ratio of 2 to 3À5: 1 must be followed by a second draw of 1.01 to 1-2: 1 applied in a separate stage whilst the tow is heated, e.g. by a hot plate, to at least 110 C. The tow is then cut and the fibres are heat set, e.g. at 130 to 200 C. " Crimp index " is defined as (1 1 -1 0 )/1 1  x 100% where 1 1  and 1 0  are respectively the fibre lengths measured under loads of 0-1 g./den. and 0-0005 g./den. respectively. " Crimp level " is defined as the number of helical turns, including fractions, in length 1 0 , divided by length 1 1 . The mean rate of instantaneous modulus is obtained from a curve of load in gram/denier and extension, by taking the difference between the tangent slopes at the 5% and 10% points measured in gram/denier/ unit strain and dividing by 0.05. The fibres may be made in an apparatus part of which is illustrated diagrammatically in the drawing in which the filaments are melt extruded through a row of holes (2) which are in an annular trough (3) of a circular spinneret (1) and which are arranged in a circle and the filaments are taken to a ceramic traverse guide (not shown in the drawing) associated with a wind-up mechanism. Between this and the spinneret (1) there is a quenching body (4) consisting of a hollow porous ceramic shell (6) with an inlet 5 for water (which is the quenching liquid). The largest diameter of the quenching body (4) which is of circular shape in plan view, is 3.5 inches tapering at the lower end to 3.25 inches. The top tapers to a smaller diameter. The angle between tangent to the upper and lower portions of the quenching surface may be 20 degrees. Alternatively the upper portion of the quenching surface may be rounded. The top and bottom of the ceramic shell 6 is sealed by rubber gaskets (8) held by brass plates 9 and 10 clamped by screws 11 and 12 threaded on the bolt 13. The distance between the spinneret orifice and the first horizontal peripheral line of initial contact of the filaments on the quenching surface is 5 inches. A convergence guide in the form of a circular ring of about 1 cm. internal diameter is 5 feet lower down along the threadline.