| 摘要 |
<p>Paper or cardboard prodn. involves forming a sheet from a pulp contg. CaO3, resin and Al sulphate and drying. In the first stage, pulp, beaten with fresh water and/or process water free from suspended (in)organic matter, is treated with resin size and enough Al sulphate to fix the size. CaCO3 is added in a second stage. Alkali hydroxide (NaOH) is added to pH 6.0.7.2 between these 2 stages. The amt. of resin size used is 1.4-3 wt.% w.r.t. abs. dry matter. CaCO3 is added in the form of waste contg. CaCO3. Before addn., this can be sized with synthetic size(s), i.e. ketone dimers, mono- or di-carboxylic anhydrided, NCO cpds., carbamoyl chloride and other carbamoyl cpds. Alkali hydroxide is added to the sized waste or the pulp obtd. in the first stage at most in the amt. needed to neutralise the Al sulphate added in the first stage. Losses and operating difficulties are avoided.</p> |
