| 摘要 |
In the process of the parent Specification for producing polyvinyl alkanals by reacting 1 mol. of a polyvinyl alcohol or ester (e.g. the acetate or propionate) with 0.1-1.0 mols. of a C8-C16 oxo-aldehyde, substantially linear products are obtained by performing the reaction in the presence of a heterocyclic compound, having oxygen in the heterocyclic ring, which is a mutual solvent for the polyvinyl alkanal and both of the starting materials. Specified solvents are dioxane, C1-C4 alkylated dioxanes, dioxolane, and C1-C3 alkylated dioxolanes. Catalysts for the reaction are hydrochloric, sulphuric and phosphoric acids. At the end of the reaction the polyvinyl alkanol is precipitated by adding a mixture of an alcohol and water and, after washing with a similar solvent mixture, is dried in vacuo. The polyvinyl alkanal is soluble in the oxygen-containing heterocyclic compounds mentioned above and also in benzene, toluene, xylene, mineral spirits, chloroform, trichloroethane, carbon tetrachloride and carbon disulphide, and may be compounded with plasticizers, e.g. dioctyl phthalate, didecyl phthalate, dioctyl adipate or trioctyl phosphate, or with anti-oxidants, pigments, dyes or fillers. Cross-linking may be effected by reaction with a diisocyanate or diisothiocyanate. The polyvinyl alkanals may be used in the manufacture of moulded products, adhesives, coating compositions or fibres. For the last purpose, the polyvinyl alkanals may be melt-spun by feeding them into a screw extruder heated to 200 DEG C., extruding through a fine aperture held in a vertical plane and taking up the filament on a drum revolving at a speed sufficient to stretch the filament. Alternatively, they may be wet-spun by dissolving them in dioxane or other solvent specified above and passing the solution through a spinneret into a coagulating bath containing, for example, a mixture of water and methanol maintained at room temperature. They may also be dry-spun by spinning a solution in the oxygen-containing heterocyclic compound into a heated gas. The resulting fibres may be cold-drawn. |
