| 摘要 |
PURPOSE:The titled modified PVA useful as an adhesive for corrugated cardboard, etc., having improved initial and equilibrium bond strength, suitable for quick lamination comprising a unit of ethylenic unsaturated carboxylic acid, having an amount in a specific range of a soluble matter which is obtained by dispersing the unit in water followed by heating. CONSTITUTION:A copolymer of an ethylenic unsaturated carboxylic acid(e.g., itaconic acid, etc.) and vinyl acetate is saponified, for example, in a methanol solution of sodium methylate, to give a modified polyvinyl alcohol having 0.1- 10mol% unit of ethylenic unsaturated carboxylic acid 0.1-10mol%, a soluble matter at 40 deg.C not more than 5wt% obtained by heating the dispersion of the modified polyvinyl alcohol in water at a rate of temperatur increase 1 deg.C per minute from 20-90 deg.C, and a 85-100wt% soluble matter at 60 deg.C. Not less than 1wt% modified polyvinyl alcohol is added to an unpasted starch to give an aqueous suspension, which is blended with a pasted starch to give an adhesive composition for corrugated cardboards. |
