| 摘要 |
In the production of coated non-fibrous regenerated cellulose wrapping material (see Group VIII) the uncoated film is impregnated with a water-soluble, partially condensed guanidine-carbamide aldehyde resin obtained by reacting an aldehyde, guanidine and a carbamide in the proportion of 1-4 mols. aldehyde, and 0.02-0.25 mol. guanidine per mol. carbamide. The film is hardened by coating it with a coating composition containing an acid hardening agent, e.g. maleic, itaconic, ethyl acid phosphoric, para-toluene sulphonic, phosphoric, acetic, hydroxy acetic, dichloracetic, "petrex," oxalic, salicylic, malonic, periodic, fumaric, tartaric, picric acids. Aldehydes specified are: formaldehyde, acetaldehyde, benzaldehyde, furfuraldehyde. Carbamides specified are: urea, thiourea, and monoalkyl, aryl or acyl-substituted ureas. Example (1), 0.04 mols. guanidine nitrate are dissolved in 2.3 mols. formaldehyde (37 per cent); the pH is adjusted to 5.3 with aqueous Na2CO3 or NaOH; 1 mol. urea is added and the mixture boiled under reflux for 2 hours. The clear solution is cooled and stabilized by adjusting the pH to 6.5-7. Specifications 283,109, [Class 140], 446,383 and 541,559 and U.S.A. Specifications 2,017,866, 2,147,180 and 2,236,546 are referred to. |
