Patent GB-356408-A (GB)
Title: Manufacture of highly viscous solutions from polyvinyl alcohols
IPC: B44B5/02
Filed: 1930-07-29
Abstract: Highly viscous solutions useful for making emulsions are prepared by treating aqueous solutions of polyvinyl alcohols with an aldehyde, or an agent yielding an aldehyde, under such mild conditions that products insoluble in water are not formed.  A small amount of an acid catalyst, e.g. lactic, phosphoric, or hydrochloric acid may be added, but the catalyst should be eliminated, e.g. by neutralization, when the reaction has proceeded to the desired stage.  Any excess of aldehyde is preferably eliminated also, e.g. by addition of ammonia. According to the examples, (1) an aqueous polyvinyl alcohol solution, obtained by saponifying a polyvinyl acetate, is treated with formaldehyde solution at 60-65 DEG  C.; a viscous solution suitable for making emulsions of insoluble dyes is obtained; the solute may be isolated by precipitation with alcohol; (2) a viscous polyvinyl acetate, prepared by polymerizing vinyl acetate in the presence of paraformaldehyde, is saponified and the polyvinyl alcohol so obtained is dissolved in water; the solution is treated at 60-65 DEG  C., with paraformaldehyde, and then diluted and treated with sufficient ammonia to eliminate the excess of aldehyde; (3) an aqueous polyvinyl alcohol solution is treated at 70-80 DEG  C. with a glyoxal solution containing oxalic acid; (4) an aqueous polyvinyl alcohol solution obtained by saponifying vinyl chloracetate is warmed with acetaldehyde and a little hydrochloric acid, which is neutralized when the desired increase in viscosity has been attained; (5) an aqueous solution of a partly saponified polyvinyl acetate is treated at 80-85 DEG  C. with aldol and lactic acid, the latter being afterwards neutralized; (6) an aqueous solution of a viscous polyvinyl alcohol is warmed with benzaldehyde; (7) an aqueous solution of a low-polymerized polyvinyl alcohol is treated with adol at 80-85 DEG  C.; (8) an aqueous solution of a low-polymerized polyvinyl alcohol is treated with glucose and glycollic acid, and the product is neutralized and rendered fluid by dilution with water. The use of chloral or butyraldehyde as the aldehyde is referred to. The Specification as open to inspection under Sect. 91 (3) (a) states that the solution used in example 5 is an alcoholic solution.  This subject-matter does not appear in the Specification as accepted.ALSO:Highly viscous solutions useful for making emulsions and printing pastes and for sizing textile fibres, are prepared by treating aqueous solutions of polyvinyl alcohols with an aldehyde, or an agent yielding an aldehyde, under such mild conditions that products insoluble in water are not formed.  A small amount of an acid catalyst, e.g. lactic, phosphoric, or hydrochloric acid may be added, but the catalyst should be eliminated, e.g. by neutralization, when the reaction has proceeded to the desired stage.  Any excess of aldehyde is preferably eliminated also, e.g. by addition of ammonia. According to the examples, (1) an aqueous polyvinyl alcohol solution, obtained by saponifying a polyvinyl acetate with sulphuric acid, is treated with formaldehyde solution at 60-65 DEG  C.; a viscous solution suitable for making emulsions of insoluble dyes or for sizing, dressing or printing is obtained; the solute may be isolated by precipitation with alcohol; (2) a viscous polyvinyl acetate, prepared by polymerizing vinyl acetate in the presence of paraformaldehyde, is saponified with an aromatic sulphonic acid, and the polyvinyl alcohol so obtained is dissolved in water; the solution is treated at 60-65 DEG  C. with paraformaldehyde, and then diluted and treated with sufficient ammonia to eliminate the excess of aldehyde; (3) an aqueous polyvinyl alcohol solution is treated at 70-80 DEG  C. with a glyoxal solution containing oxalic acid; (4) an aqueous polyvinyl alcohol solution obtained by saponifying vinyl chloracetate is warmed with acetaldehyde and a little hydrochloric acid, which is neutralized when the desired increase in viscosity has been attained; (5) an aqueous solution of a partly saponified polyvinyl acetate is treated at 80-85 DEG  C. with aldol and lactic acid, the latter being afterwards neutralized; (6) an aqueous solution of a viscous polyvinyl alcohol is warmed with benzaldehyde; (7) an aqueous solution of a low-polymerized polyvinyl alcohol is treated with aldol at 80-85 DEG  C.; (8) an aqueous solution of a low-polymerized polyvinyl alcohol is treated with glucose and glycollic acid, and the product is neutralized and rendered fluid by dilution with water.  The use of chloral or butyraldehyde as the aldehyde is referred to.  The Specification as open to inspection under Sect. 91 (3) (a) states that the solution used in example (5) is an alcoholic solution.  This subject-matter does not appear in the Specification as accepted.ALSO:Highly viscous solutions useful for sizing textile fibres are prepared by treating aqueous solutions of polyvinyl alcohols with an aldehyde, or an agent yielding an aldehyde, under such mild conditions that products insoluble in water are not formed.  A small amount of an acid catalyst, e.g. lactic, phosphoric, or hydrochloric acid may be added, but the catalyst should be eliminated, e.g. by neutralization, when the reaction has proceeded to the desired stage.  Any excess of aldehyde is preferably eliminated also, e.g. by addition of ammonia. According to the examples, (1) an aqueous polyvinyl alcohol solution, obtained by saponifying a polyvinyl acetate, is treated with formaldehyde solution at 60-65 DEG  C.; a viscous solution suitable for sizing is obtained; the solute may be isolated by precipitation with alcohol; (2) a viscous polyvinyl acetate, prepared by polymerizing vinyl acetate in the presence of paraformaldehyde, is saponified and the polyvinyl alcohol so obtained is dissolved in water; the solution is treated at 60-65 DEG  C. with paraformaldehyde, and then diluted and treated with sufficient ammonia to eliminate the excess of aldehyde; (3) an aqueous polyvinyl alcohol solution is treated at 70-80 DEG  C. with a glyoxal solution containing oxalic acid; (4) an aqueous polyvinyl alcohol solution obtained by saponifying vinyl chloracetate is warmed with acetaldehyde and a little hydrochloric acid, which is neutralized when the desired increase in viscosity has been attained; (5) an aqueous solution of a partly saponified polyvinyl acetate is treated at 80-85 DEG  C. with aldol and lactic acid, the latter being afterwards neutralized; (6) an aqueous solution of a viscous polyvinyl alcohol is warmed with benzaldehyde; (7) an aqueous solution of a low-polymerized polyvinyl alcohol is treated with aldol at 80-85 DEG  C.; (8) an aqueous solution of a low-polymerized polyvinyl alcohol is treated with glucose and glycollic acid, and the product is neutralized and rendered fluid by dilution with water. The use of chloral or butyraldehyde as the aldehyde is referred to. The Specification as open to inspection under Sect. 91 (3) (a) states that the solution used in example 5 is an alcoholic solution.  This subject-matter does not appear in the Specification as accepted.