Patent GB-883037-A (GB)
Title: Method of treating polyvinyl alcohol so as to improve its dyeability
IPC: D06P1/66
Filed: 1959-07-06
Abstract: The dyeing properties of polyvinyl alcohol are improved by acetalizing the alcohol with an aldehyde containing a quaternary ammonium group.  Several methods of procedure are indicated, as follows.  (1) Polyvinyl alcohol fibres are partially acetalized with a compound containing a quaternary ammonium group and an aldehyde group and may then be further acetalized with another aldehyde, e.g. formaldehyde.  (2) Polyvinyl alcohol is treated, as such or in aqueous solution, with the quaternary ammonium compound and the product is dissolved (if necessary) to give a spinning solution to which untreated polyvinyl alcohol may be added.  (3) Compounds containing a quaternary ammonium group and a group convertible into an aldehyde group under the reaction conditions may be used in the process, as may also the addition compounds of the aldehydes with compounds such as sodium bisulphite, hydroxylamine, substituted hydrazines and semicarbazide.  (4) The quaternary ammonium compound may be produced in situ; thus, polyvinyl alcohol which has been partly acetalized with a halogenated aldehyde may be after-treated with a tertiary amine, or acetalization with an aminoaldehyde may be followed by after-treatment with an alkylating agent.  In the Examples, (1) polyvinyl alcohol fibres which have been heat-treated under tension are treated in an aqueous bath containing sulphuric acid, sodium sulphate and (1 - methyl - 3,3 - dimethoxypropyl) - trimethylammonium iodide or (Example 2) (3,3-dimethoxypropyl)-cyclohexyldimethylammonium sulphate or (Example 4) bis-(3,3-dimethoxypropyl)-dimethylammonium chloride; (3) staple fibre of polyvinyl alcohol, after heat treatment, is treated in an aqueous bath containing sulphuric acid, sodium sulphate and (2,2-diethoxyethyl)-trimethylammonium hydroxide, and is then treated in an aqueous bath containing sulphuric acid, sodium sulphate and formaldehyde; (5) polyvinyl alcohol fibre is stretched in two successive baths of Wood's alloy and then treated first with an aqueous bath containing sulphuric acid, sodium sulphate and (p-formylphenyl)-trimethylammonium iodide and then with an aqueous bath containing sulphuric acid, sodium sulphate and terephthalaldehyde; (6) a solution of polyvinyl alcohol in aqueous sulphuric acid is heated at 70 DEG C. with (p-formylphenyl)-trimethylammonium iodide and the product, after addition of caustic soda, is purified by dialysis through parchment paper; the acetalized product is evaporated and redissolved in water, together with untreated polyvinyl alcohol, to form a spinning solution, the fibres spun from which are treated with an aqueous bath containing sulphuric acid, sodium sulphate and formaldehyde; (7) polyvinyl alcohol powder is treated at 60 DEG C. with an aqueous solution containing sulphuric acid, sodium sulphate and (p-formylphenyl)-trimethylammonium sulphate and the product is filtered; the filter residue is dissolved in aqueous caustic soda to give a spinning solution of pH 7, and the fibres spun from this solution are treated with an aqueous bath containing sulphuric acid, sodium sulphate and formaldehyde; (8) polyvinyl alcohol is partly acetalized with b -cyclohexylaminopropionaldehyde and the product is treated with an aqueous methanol bath containing methyl iodide; after addition of sodium carbonate, the product is purified by dialysis and then mixed with untreated polyvinyl alcohol and water to form a spinning solution.  Other suitable quaternary ammonium compounds are specified.