Patent GB-927100-A (GB)
Title: Polyester filaments
IPC: D01D5/08
Filed: 1960-12-22
Abstract: <PICT:0927100/IV(a)/1> A crimped synthetic linear glycol-terephthalate polymer filament has a tenacity of 2 to 4,5 gpd in the 1 to 6 denier per filament range, a break elongation of 15 to 45%, an initial modulus of 500 to 1,000 Kg./mm.2, a compliance ratio of 0,4 to 0,8, a crimp index value of 15 to 70%, and a differential birefringence across the width of the filament.  The filament may have 4 to 13 helical crimps per inch.  The filament polymer may have the general formula HO-G-(OOC-A-COO-G)y-OH where -G- and -A- are divalent organic radicals corresponding, respectively, to the radical in the initial glycol, G(OH)2, and in the initial dicarboxylic acid, A(COOH)2, and y is a number sufficient that the polymer is of fibre-forming molecular weight, at least 75% of the -G-radicals being ethylene radicals and at least 75% of the -A- radicals being terephthalate radicals.  The initial modulus is defined as the slope of the first reasonably straight portion of a stress-strain curve of a fibre obtained by plotting tension on a vertical axis against elongation on a horizontal axes as the fibre is being elongated at the rate of 10% per minute at 21 DEG C. and 60% RH, and is expressed in units of Kg./mm.2 per 100% elongation.  The compliance ratio is associated with the shape of the stress-strain curve and is a measure of the rate of change of compliance with elongation.  Compliance is defined as elongation divided by tension in Kg./mm.2.  This property is measured by determining the average rate at which compliance changes in the range of 5 to 10% elongation and is computed by the formula 1/5 (10/tension at 10% elongation-5/tension at 5% elongation). The crimp index is obtained by measuring the length of the fibres hanging under an added load of 0,1 gpd for a period of 2 seconds (length A), and the length of the same fibres hanging under no added weight after they have relaxed for 15 seconds from the first extension (length B).  The crimped tow from which the staple fibres are derived may be used in place of the fibres.  The crimp index= <FORM:0927100/IV(a)/1> In an example, polyethylene terephthalate is melt spun at about 290 DEG C. through a spinning head comprising inlets 1, sand pack 2, channels 3 and 5 and spinneret 8 having 900 round orifices 7 each 0,007 inch in diameter arranged in 6 concentric circles whose radii differ by 0,052 inch, the smallest circle having a radius of 1,437 inches.  Filaments 9, which are closely spaced in a series of 6 concentric rings are immediately quenched by a strong flow of air at room temperature from the annular nozzle 10 of 4 1/8 inches inside diameter and having an opening 0,5 inch high spaced 3/16 inch below the spinneret face by a ring of aluminium foil and asbestos cloth.  The temperature of the spinneret is controlled by band heater 15 and the spinneret is thermally insulated by the disc of insulation material 16.  The individual as-spun filaments under a polarizing microscope exhibit a refractive index differential from one side of the filament to the other.  A tow of the filaments is passed through an aqueous bath containing a textile finishing agent, drawn at a draw ratio of 3 to 3,5 in an aqueous spray at 95 DEG C., the drawing tension released, the filaments cut into 2,2 inch lengths and relaxed for 15 minutes in a hot air oven at 140 DEG C.  The filaments thereafter exhibit 8 helical crimps per inch.  An example is furnished of the weaving of twill fabric from a yarn consisting of equal parts of crimped staple dyed polyester fibres of the invention and dyed wool.  Examples are also furnished of the preparation of 100% polyester tropical fabrics, 55 polyester/45% wool tropical fabrics, and 65% polyester/35% rayon gabardine fabrics.  An example is also furnished of the use of crimped polyester fibres of the invention as a filling for a pillow. Crimped tow and crimped staple fibres of the invention possess superior bulking properties and fabrics made therewith have a degree of loft and cover unobtainable with conventional crimped polyethylene terephthalate fibres. Specifications 536,380, 578,079, 712,950, 796,019 and 824,577 are referred to.