Patent GB-1167696-A (GB)
Title: Polyamide Monofilament
IPC: D01D10/04
Filed: 1968-02-14
Abstract: 1,167,696. Brushes. E. I. DU PONT DE NEMOURS & CO. 14 Feb., 1968 [17 Feb., 1967], No. 7285/68. Headings A4K and A4V. [Also in Divisions B5 and D1] A synthetic polyamide monofilament has a surface structure which is etched and which has irregular ridges in a direction predominantly transverse to the length of the filament. Where such a filament has a diameter of from 3 to 150 mils, it is particularly useful where a cleaning or scrubbing action is desired, as in hairbrushes, where the surface structure helps to remove and hold dirt, in tooth-brushes and other wet-surface brushes where the roughness serves both to scrub the surface and to hold large volumes of the cleaning medium, and its dull appearance renders it suitable for use in wigs and personal brushes; the average height of the ridges may be at least 0.2 mls, and is desirable at least 0.5 mils. Such filaments may have an average ridge factor of at least 2, and preferably at least 4. The ridge factor F, is defined by the equasion FR = 10H(W/S), where H is the distance from the bottom of a valley to the top of a peak on the filament surface, and W is the width of ridge measured from trough to trough, and S is the separation of the ridges measured from peak to peak. Alternatively the filament may have a diameter of from 0.5 to 3 mils, and the average height of the ridges may then be at least 0.02 mls, and the average ridge factor at least 0.1. Preferred materials include polyhexamethyleine adipamide, polyhexamethylene sebacamide, polycaprolactam, the polyamide formed from 1, 4- (cis)-(cyclohexane-bis (methylamine) and adipic acid, the polyamide from m-xylylene diamine and adipic acid, the polyamide from 3, 5-dimethyl-hexamethylene diamine and terephthalic acid, the polyamide from 2, 5-dimethylpyserazine and adipyl chloride, copolymers of polycaprolactam and polyhexamethylene adipamide; copolymers of polyhexamethylene adipamide and polyhexamethylene seba camide wherein the weight percentage of the latter monomer in the copolymer is up to 20 per cent or over 80 per cent, and polyamides from bis (4-aminocyclohexyl) methane and dicarboxylic acids containing 6-14 carbon atoms. The preferred polyamides are polyhexamethylene adipamide and polyhexamethylene sebacamide. The filament to be treated can be made using any of the conventional extrusion and drawing techniques, and its diameter can vary widely. In examples, the filaments to be treated are drawn in a single stage draw operation to a draw ratio of 4.0, or sometimes 4.4, and may then be conditioned at 180‹C. in the air for 90 seconds. Following this pretreatment, the filament is then contacted with steam at a pressure of from 100-150 psig for a contact time of from 0.1-10 seconds. The filaments are suitably treated in a steam tube, while held under sufficient tension to take up any slack. A suitable steam tube consists of an outer jacket or pipe and a perforated core. Steam is introduced into the space between the outer pipe and core and passes through the opening and into contact with the filament which continuously enters and exists at either end of the core. In examples, the steam tubes are composed of half inch stainless steel pipe over an inner stainless steel tube with a 125 mil outside diameter and an inside diameter of either 55 or 85 mils, depending on the diameter of the filament to be treated. The inner tube has a plurality of 1/16 inch openings drilled radially along its length, and steam is admitted into the outer jacket and passed through the openings into the core, the overall length of both the outer pipe and core being 6 inches.