Alkali-methanol cooking has been studied as one of the pollution free pulping methods. The results obtained are summarized as follows.
(a) Delignification by alkali-methanol cooking is more rapid than that by kraf t cooking. Pulp yield by the former is 7 8% higher than that by the latter.
(b) One of the optimum cooking conditions is as follows : cooking liquor (40 g sodium hydroxide and 400 g methanol) /l, max. temperature 160, 30 '60 min. at 160 °C.
(c) The ratio of dissolved lignin/dissolved carbohydrate in alkali-methanol cooking is 3.2 3.5 and is much higher than that in kraf t cooking. This means that alkali-methanol cooking results more rapid dissolution of lignin and higher retention of carbohydrate than kraf t cooking.
(d) Higher pulp yield by alkali-methanol cooking was discussed from a point of the behavior of lignin and of carbohydrate during cooking. It may be possible that the methylation of benzylalcohol group of lignin with methanol occurs during alkali-methanol cooking and prevents the condensation at α-position of lignin side chain.