| 摘要 |
1,036,787. Producing acetalized polyvinyl alcohol fibres. KURASHIKI RAYON KABUSHIKI KAISHA. July 1, 1963 [Aug. 9, 1962], No. 25975/63. Heading B5B. Acetalized polyvinyl alcohol fibres are made by stretching polyvinyl alcohol fibres at 180‹ to 250‹ C. and at a stretch ratio of 5 to 12, contacting the stretched fibres with an aqueous solution containing either (1) a phenolic compound, (2) boric acid or a water-soluble borate, or (3) an aliphatic water-soluble lower aldehyde such as formaldehyde or acetaldehyde, optionally washing with cool or warm water, and either with or without first drying then acetalizing with an aromatic aldehyde such as benzaldehyde, chlorobenzaldohyde or naphthaldehyde, or with a hydroaromatic aldehyde ketone or acetal. In an example, filaments formed by dry spinning a solution of a polyvinyl alcohol having a D.P. of 1700 and which had been polymerized at 60‹ C. are stretched at 230‹ C. and a stretch ratio of 10, heat set at 230‹ C. while allowing them to shrink 20%, immersed for 3 hours in a 5% aqueous solution of phenol at 50‹ C., washed with water at 60‹ C., air dried, and acetalized at 60‹ C. for 6 hours in a bath consisting of 2% benzaldehyde, 15% sulphuric acid, 35% methanol and 48% of water. The PVA used may have been polymerized at a temperature of - 60‹ C. t o + 20‹ C. and/or may have a degree of polymerization of 900 to 1500. If the treatment with an aqueous solution of phenol &c. after the hot stretching and heat setting step is omitted, the fibres cannot be acetalized to the extent desirable to render the fibres resistant to shrinkage in hot water. |
