Patent GB-938055-A (GB)
Title: Polyester shaped articles
Inventor: RICHARDS GEORGE
IPC: D01F6/62
Filed: 1960-11-17
Abstract: Filaments and staple fibres having an intrinsic viscosity in filament or fibres form of 0,35 to 0,49, measured on an 8% (weight/volume) solution in orthochlorophenol at 25 DEG C. are made from synthetic co-polyesters derived from terephthalic acid and containing 3-12 mole per cent of a second dicarboxylic acid of formula HOOC-R-COOH where R is polymethylene or arylene other than paraphenylene.  The staple fibres are crimped, have a residual shrinkage in boiling water for 1 minute of less than 1%, are substantially free from coalesced and partly drawn lengths, are dyeable at the boil to heavy shades with disperse dyes, being capable of taking up at least 14 mg./g. of "Dispersol" Fast Scarlet B, (as defined) and the fibres form not more than 5 pills per sq. inch of fabric (as defined).  The co-polyesters may be obtained by heating n mole per cent of the second acid, e.g. sebacic or adipic acids, with a composition comprising di-(b -hydroxyethyl) terephthalate and polymers thereof having an average molecular weight not exceeding 19,200-130 n/n, or by ester-exchange of mixtures of the esters of terephthalic acid and the second dicarboxylic acid with glycols of the series HO(CH2)nOH where n is 1-10, or with 1:4-dihydroxy-methyl cyclohexane, provided that the final co-polyester contains 3-12 mole per cent of the second dicarboxylic acid.  The co-polyester is extruded through a filterpack and multi-hole spinneret below which the filaments are cooled while being stretched, with a uniform stream of gas, e.g. air, directed outwards at 7,5 to 61 m./min. from a region substantially in the centre of the array of filaments and at a distance beginning at 1,3 to 6,5 cms. below the face of the spinneret (see Specification 938,056), but such that the gas does not cool the face of the spinneret.  The filaments are subsequently drawn to a ratio of 1:3 to 1:5 at a temperature between the second order transition temperature and 100 DEG C., crimped and treated with steam at 120 DEG  to 180 DEG C. until the required condition of shrinkability and dyeability are satisfied. The spinneret holes are preferably non-circular (see Specification 919,047), and suitably contain 100-500 holes of cruciform Y- or T-shape of aspect ratio (as defined) up to 1:35 and of area 0,19-0,65 sq. mm.  Spinning conditions are such that the reduction in intrinsic viscosity from the manufacture of the co-polyester to conversion into stable fibres is not more than 0,005. In an example, sebasic acid is heated with the reaction product of dimethyl terephthalate and ethylene glycol using calcium acetate as catalyst.  Polymerization is effected in presence of phosphorous acid, antimonic acid and titanium oxide, to give a melt containing 6 mole per cent of sebacate, and with intrinsic viscosity 0,47.  The co-polyester is spun at 254 DEG C., the filaments being cooled below the spinneret face by a stream of air directed radially outwards at 26 m./min. from a quench source, positioned centrally below the spinneret, comprising a vertical cylinder of stainless steel mesh, 25 cms. long, sealed at the top end and provided with an inlet at the bottom.  A steel rod mounted axially along the cylinder carries 10 steel mesh slices positioned at equal intervals and increasing in diameter from the inlet part, to distribute the stream of air radially outward.  The spun filaments are collected and drawn to a ratio of 1:4,6 in a zone heated to 80 DEG C. by air, steam or water. The tow is crimped, dried and steamed at 140 DEG C. for 20 minutes. Specifications 919,860 and 931,241 also are referred to.