GB818930A - Method of continuously removing residue shrinkage from a tow of continuous filamentsof acrylonitrile polymer - Google Patents

Abstract

The residual shrinkage is removed from a tow of continuous filaments of acrylonitrile polymer capable of being further shrunk by passing the tow continuously in a relaxed state through a zone of liquid and/or vapour at a temperature of 99 DEG to 110 DEG C., each portion of the tow being maintained in the zone for at least 5 seconds. Suitable treating liquids and vapours are water, steam, ethylene glycol, diethylene glycol, ethylene glycol monoethyl ether, glycerol and propylene glycol. The filaments may be produced by dry or wet spinning and are preferably dried and then rewetted before treatment. Treatment may be carried on in a J-box provided at its inlet end with spray means for introducing treating liquid at the desired temperature, alternately first from one side and then from the other (see Group IV (c)). The spray means are so combined with a traversing mechanism that the tow falls in the bottom of the J-box in a tensionless plait. The tow may be composed of filaments of homopolymers of acrylonitrile or of copolymers, preferably containing at least 40 per cent by weight of acrylonitrile in the molecule, of acrylonitrile with vinyl esters of saturated aliphatic monocarboxylic acids, e.g. vinyl acetate, vinyl propionate and vinyl butyrate, vinyl and vinylidene halides, e.g. vinyl and vinylidene chlorides, bromides and fluorides, allyl-type alcohols, e.g. allyl alcohol, methallyl alcohol and ethallyl alcohol, allyl, methallyl and other unsaturated monohydric alcohol esters of monobasic acids, e.g. allyl and methallyl acetates, laurates and cyanides, acrylic and alkacrylic acids, and esters and amides of such acids, methacrylonitile, ethacrylonitrile, other hydrocarbon-substituted acrylonitriles, unsaturated aliphatic hydrocarbons containing a single CH2=C< group and alkyl esters of alpha, beta-unsaturated polycarboxylic acids. Filaments of mixtures or blends of different polymers including a polymer of acrylonitrile, e.g. a mixture of polymerized 2-methyl - 5 - vinylpyridine and a copolymer of acrylonitrile with acrylic acid, acrylamide, vinyl acetate or methyl acrylate, may be treated.ALSO:<PICT:0818930/IV (c)/1> <PICT:0818930/IV (c)/2> In a process for continuously removing residual shrinkage from a tow of continuous filaments of acrylonitrile polymers, capable of being further shrunk, in which the tow is passed continuously in a relaxed state through a zone of liquid and/or vapour at a temperature of 99 DEG to 110 DEG C., the treatment is carried out in a J-box provided at its inner end with spray means for introducing treating liquid at the desired temperature alternately from two opposite sides. In Fig. 1 the tow 10 is wetted with water in the wetting device 12, in order to facilitate subsequent handling, and passes to traverse mechanism 34 comprising a metal block 110, provided with a bracket 116 holding tow guide 118, which is fastened to traversing rod 114 and is guided in its reciprocating motion by stationary guide rod 112. The metal block 110 is also provided at its upper end with a yoke 80 having arms 78, 88 which have adjusting means for actuating the switch lever 82 at the desired point in the cycle for controlling the configuration of the deposit of tow. From the traverse mechanism the tow passes over rolls 36, 38, 40 to the inlet end 48 of the J-box. In operation the tow entering the J-box at corner 64 (Fig. 3) with the traverse mechanism 34 travelling from front to back is caused to travel towards the back wall 51. Electric current is supplied through the power line 65, and switch 66, e.g. a maintained contact-limit, single-pole, double-throw switch, is in such a position that valve 68, through which treating liquid is introduced to spray means 52 through conduit 70, is held open by the current, the valve 72 being closed, and the tow reaches corner 84. When the traverse mechanism 34 reaches the back end of its stroke, the arm 78 of the yoke 80 forces the switch-actuating lever 82 into its alternate position, causing the switch 66 to open the circuit to valve 68 and close the circuit to valve 72. Valve 68 then closes and valve 72 opens, supplying liquid to spray means 54 so that the tow is forced towards the corner 86. When the traverse mechanism reaches the front of its stroke and the tow is approaching the corner 87, the arm 88 of the yoke 80 forces the switch-actuating lever 82 to its original position, causing the switch 66 to close the circuit to valve 68 and open the circuit to valve 72, so that the valve 68 is opened and valve 72 is closed and liquid enters the spray means 52 and passes thence through the openings 58, forcing the tow towards corner 64; the operation then repeats. The plaited tow is carried down to the middle portion 92 of the J-box, which is jacketed, a hot fluid medium being introduced through conduit 94 into the jacket and withdrawn through conduit 96. The J-box is provided with a conduit 98 through which excess liquid may be drained from leg 108 of the J-box to the receptacle 104.