Patent GB-723952-A (GB)
Title: Dilute aqueous dispersions of n-alkoxymethyl polyamides and their application
IPC: B44C1/16
Filed: 1952-10-29
Abstract: Filaments, fabrics, stockings or films made of wool, cotton, rayon, nylon, acrylonitrile polymers, ethylene polymers, polyethylene terephthalate or leather, or combinations thereof are treated with an aqueous dispersion comprising (1) 0.01-0.5 per cent based on the total weight of the dispersion of an N-alkoxymethyl polyhexamethylene adipamide having alkoxymethyl groups attached to from 20 to 60 per cent of the amide nitrogen atoms; (2) a dispersing agent; and (3) a stabilizing agent comprising a water-soluble salt of an acid having an ionization constant for the first or only hydrogen of at least 1 x 10-5 at 25 DEG  C.  There thus results improved properties such as increased abrasion resistance, increased snag resistance, anti-static properties, dye fastness, dimensional stability, increased water absorption, a better hand, a delustring effect, a reduction in fabric slippage and increased tensile strength.  The dispersion contains at least 50 per cent water and may also contain water-miscible or water-immiscible liquids, e.g. methanol, ethanol, isopropanol, n- or tertiary-butanol, benzyl alcohol, furfuryl alcohol, phenol or acetone.  The size of the particles is preferably from 0.1 microns or less to 10 microns.  The dispersing agent may be anionic, cationic or non-ionic and suitable ones are the sodium or triethanolamine salts of sulphated alcohols, the sodium salts of alkyl or aryl sulphonic acids, the alkyl aryl polyether alcohols, the quaternary ammonium salts and casein.  The dispersion may also contain pigments, dyes, delustring agents, curing agents, urea, thickening agents, anti-static agents, flame retarding agents, water repellants, anti-oxidants, heat stabilizers, e.g. sodium phenyl phosphinate, plasticizers, e.g. N-ethyl toluene sulphonamide, temporary plasticizers, e.g. diethylene glycol, fillers, or dimensional stabilizers, e.g. urea- or melamine-formaldehyde resins. Co-dispersions may be prepared with unmodified polyamides, natural or synthetic rubbers, natural resins, or ethylene polymers.  Exhaustion of the dispersion on to textile fabrics is normally performed by lowering its pH, preferably by citric acid.  The fabric may be immersed in the dispersion either before or after the dispersion has been acidified or the fabric may be acidified before being treated with the dispersion.  Alternatively exhaustion may be effected by heating the dispersion bath or by adding an anionic dispersing agent to a bath containing a cationic dispersing agent.  Loadings of from 0.2 to 15 per cent of modified polyamide, based on the weight of the fabric are normally employed.  The fabric may be pretreated with a cationic agent, e.g. benzyl ammonium chloride, whereby improved hand is obtained.  After exhaustion of the modified polyamide on to the fabric, excess water is removed and the polyamide then cured by heating, by treating with acid or by a combination thereof.  In examples, nylon stockings are immersed in a bath of pH 6.5 containing an aqueous dispersion of N-methoxymethylpolyhexamethylene adipamide containing alcohol, sodium lauryl sulphate, ammonium citrate and citric acid and the bath agitated to effect exhaustion.  The stockings are then centrifuged to remove water and the finish cured by heating at 120 DEG  C. for 5 minutes.ALSO:An aqueous dispersion comprises (1) 0.01-0.5 per cent based on the total weight of the dispersion of an N-alkoxymethyl polyhexamethylene adipamide, having alkoxymethyl groups attached to from 20 to 60 per cent of the amide nitrogen atoms; (2) a dispersing agent; and (3) a stabilizing agent comprising a water-soluble salt of an acid having an ionization constant for the first or only hydrogen of at least 1 X 10-5 at 25 DEG  C. The pH of the dispersion is preferably 2.0-7.5 and the size of the particles from 0.1 microns or less to 10 microns.  The dispersion is preferably made by dissolving the modified polyamide in a solvent and then diluting with water.  Suitable solvents are methanol, ethanol, isopropanol, n- or tertiary-butanol, phenols and mixtures of these solvents with water.  The stability of the alcoholic solutions is improved by the addition of benzyl or furfuryl alcohol.  When the dispersions are made by diluting alcoholic solutions, the tendency of the alcohol to dissolve the modified polyamide may be counteracted by adding acetone.  The dispersing agent may be anionic, cationic or non-ionic and suitable ones are the sodium or triethanolamine salts of sulphated alcohols, the sodium salts of alkyl or aryl sulphonic acids, the alkyl aryl polyether alcohols, the quaternary ammonium salts and casein.  Suitable stabilizing agents are the sodium, potassium, ammonium, the lower alkyl amine, the alkanolamine, the pyridine or the morpholine salts of lactric, citric, chloracetic, itaconic, malonic, mesaconic, diglycolic, tartaric, maleic, hydroxyacetic, oxalic, glutaric, adipic, malic, fumaric, phthalic, salicylic, propionic, acetic, formic, phosphoric, sulphuric or hydrochloric acids.  The preferred salts are ammonium and morpholine citrate.  The dispersion may also contain pigments, dyes, delustering agents, curing agents, urea, thickening agents, anti-static agents, flame-retarding agents, water repellents, antioxidants, heat stabilizers, e.g. sodium phenyl phosphinate, plasticizers, e.g. N-ethyl toluene sulphonamide, temporary plasticizers, e.g. diethylene glycol, fillers or dimensional stabilizers, e.g. urea- or melamine-formaldehyde resins. Co-dispersions may be prepared with natural or synthetic rubbers or natural or other synthetic resins, e.g. unmodified polyamides or ethylene polymers.  The dispersions may be used for treating textile fabrics (see Group IV (c)), in which case the modified polyamide is normally precipitated onto the fabric by adding an acid, e.g. citric acid. Alternatively the dispersion is prepared with a cationic dispersing agent and precipitation is effected by adding an anionic dispersing agent.  The modified polyamide is cured on the fabric by heating in the presence of an acid, e.g. hydrochloric, sulphuric, citric, maleic, lactic or formic acids.  The dispersions may also be employed in the preparation of coatings for paper, furniture or bowling pins; adhesives; binders; impregnated articles; films and leather-like products.  In making films or sheets, the dispersions are cast onto a suitable surface, the water removed by evaporation and heat is applied to cause agglomeration of the particles.  In examples, (1) N-methoxymethyl polyhexamethylene adipamide is dissolved in aqueous ethanol and sodium lauryl sulphate and ammonium citrate added.  The solution is then added to water and the resultant dispersion agitated; (2) and (3) nylon stockings are treated with the dispersion of example (1); (4) the ammonium citrate of example 1 is replaced by other stabilizing agents.