| 摘要 |
Grease proof paper is made by bleaching a high yield sulphate pulp, delignified with oxygen-alkali, using chlorine, alkali and hypochlorite, and refining the bleached pulp. Pref. the sulphate pulp is made using a polysulphide cooking liquor contg. 2-12 g/l polysulphide. The sulphite pulp is pref. digested to a kappa coefft. of 40-100 and delignified with oxygen and alkali to a kappa coefft. of 15-40. The hypochlorite bleaching is pref. carried out such that the pH of the pulp at the end of the process is 7.0-8.5, esp. 7.0-8.0 and partic. 7.0-7.5. The bleached sulphate pulp is pref. refined to a pH of 7.0-10.0, esp. 7.5-10.0. The paper has excellent impermeability to grease and high strength, which reduces breakages in the machine. The process does not use excessive amts. of energy. The prods. are suitable for use in high speed food packaging machines. |
