GB1376756A - Flameresistant filaments - Google Patents

Abstract

1376756 Flame-resistant filaments KANEBO Ltd 9 March 1972 [9 March 1971] 11028/72 Heading B5B [Also in Division C3] A filament comprises (A) a cured novolac resin or a resin obtained by curing a mixture of a novolac resin and a resol resin containing at least 50% by weight of a novolac resin and (B) a fibre-forming thermoplastic synthetic resin in an amount of less than 60% by weight but not less than 0À1% by weight based on the total weight of the resins, said thermoplastic resin being a polyamide, polyester, polyesterether, polyolefin or polyurethane resin or a mixture of two or more such resins. The amount of thermoplastic resin may be 0À5-50% by weight based on the total weight of the cured and thermoplastic resins, preferably 1-40% and especially 5 to 30%. Novolac resins exemplified are condensation products of phenol, m-cresol, p-cresol, and a phenol-p-cresol mixture with formaldehyde, trioxane and tetraoxane, and thermoplastic resins exemplified include nylon-6, nylon 12, nylon 611, polyethylene oxybenzoate, and a polyurethane made by polymerization of toluylene diisocyanate and polyethylene adipate. Such filaments may be made by melt-spinning a mixture of an uncured resin curable to component (A) above and a fibre-forming thermoplastic synthetic resin listed at (B) above in the stated proportions and then curing novolac resin in the filament so made with a curing agent in the presence of a basic catalyst. Curing may be effected at from room temperature to 250‹ C. and the filament may be drawn, suitably up to a draw ratio of 2À5, before and/or after curing. Specified curing agents include formaldehyde, paraformaldehyde, hexamethylenetetramine, furfural, chloral, glyoxal, trioxane, tetraoxane and polyoxymethylene; hexamethylenetetramine may be added to the molten mixture to be melt-spun in an amount of up to 5% by weight of the uncured novolac resin to induce partial curing. Specified basic catalysts include ammonia, ammonium hydroxide, sodium hydroxide, potassium hydroxide and hexamethylenetetramine. The melt-spun filament may be immersed in, or run through, a bath containing the curing agent and basic catalyst at from room temperature to 45‹ C., preferably 10‹ to 40‹C., and heat-cured at 60‹ to 140‹ C., preferably 70‹ to 130‹ C., or sprayed or fumed therewith. A preferred curing agent liquid is a 5 to 40%, preferably 15-30%, aqueous solution of formaldehyde adjusted to pH 8 to 13, especially 8À5 to 11 by the addition of basic catalyst. Alternatively the filament is cured by heating in a mixed bath of hexamethylenetetramine and n-paraffinic hydrocarbon at 50‹ to 150‹ C. Filaments so made show enhanced flameresistant and antifusing properties.