Patent GB-621362-A (GB)
Title: Improvements in or relating to the production of alkali-resistant alginate materials
Filed: 1947-02-21
Abstract: Alginic materials are rendered resistant to alkalis by reacting them with di-epoxy compounds so as to produce cross-linkages between the hydroxyl and between the carboxyl groups of the alginic molecules. The alginic materials may be filaments, or films of alginic acid or metal alginates with free carboxyl groups.  The treatment renders the materials insoluble in and resistant to aqueous solutions of alkalis such as sodium carbonate or soap.  The alginic filaments or films may be swollen in water; the water may be displaced by a polar solvent such as alcohol which maintains sufficient swelling to keep the hydroxyl groups accessible: and then the materials may be boiled in a solution of the di-epoxy compound in alcohol.  If desired, the treatment with a di-epoxy compound may be associated with a treatment with other compounds having an insolubilizing effect, e.g. compounds of chromium or beryllium, formaldehyde, or a formaldehyde resin. Treatment with metal compounds may impart fire-resistance.  In an example, a hank of alginic acid is swollen in water and then passed through alcohol-water mixtures of increasing concentration, and finally absolute alcohol.  The hank is then boiled for 24 hours under reflux with a solution of hexylene dioxide in absolute alcohol.  The treated hank is resistant to soap and soda solution whereas an untreated hank dissolves in a solution of 0.2 per cent soap and 0.2 per cent soda in three minutes.  The water adsorptive capacity of the treated material is also reduced.  Specifications 541,847, 545,872, and 572,798 are referred to.ALSO:Alginic materials are rendered resistant to alkalis by reacting them with di-epoxy compounds so as to produce cross-linkages between the hydroxyl and between the carboxyl groups of the alginic molecules.  The alginic materials may be filaments, films or other articles or forms of alginic acid or metal alginates with free carboxyl groups.  The treatment renders the materials insoluble in and resistant to aqueous solutions of alkalis such as sodium carbonate or soap.  The alginic material may be swollen in water, the water may be displaced by a polar solvent such as alcohol, which maintains sufficient swelling to keep the hydroxyl groups accessible, and then the material may be boiled in a solution of the di-epoxy compound in alcohol.  The alginic material may be in the form of moulding powder for the production of plastics.  If desired, the treatment with a diepoxy compound may be associated with a treatment with other compounds having an insolubilizing effect, e.g. compounds of chromium or beryllium, formaldehyde, or a formaldehyde resin.  Treatment with metal compounds may impart fire-resistance.  In an example, a hank of alginic acid is swollen in water and then passed through alcohol-water mixtures of increasing concentration, and finally absolute alcohol.  The hank is then boiled for 24 hours under reflux with a solution of hexylene dioxide in absolute alcohol. The treated hank is resistant to soap and soda solution whereas an untreated hank dissolves in a solution of 0.2 per cent soap and 0.2 per cent soda in three minutes.  The water-adsorptive capacity of the treated material is also reduced. Specifications 541,847, 545,872, 572,798 are referred to.