稲わらの圧縮成形性に関する研究　ＩＩＩ　　試作ビータのこう解特性並びにこう解処理とソーダ処理の成形性への効果

Beating treatment of rice straw chopped at the length of 2 to 5cm and removal of rignin by changing straw's chemical state with the use of soda are important process for waferability, and also digestibility to the ruminent animal. Rice straw was beaten with beater built as a trial, and treated with soda (sodium hydroxide, sodium sulfide). The following results were obtained.<br>1. The beating efficiency was about 2.1ps per 15kg/hr being feed at the beater speed of 1200rpm.<br>2. The beating efficiency varied with shear plate angle, beater speed, feed speed, row number of knives, feed quantity and clearance between shear plate and knives. From the result of analysis of variance, it was clarified that the cutting of straw in transverse direction decreased at the beater speed of 800rpm.<br>3. There was no large difference between unbeaten chopped straw and beaten one in the nutrients.<br>4. By spraying 5 to 15% concentrated sodium hydroxide with the rate of 10 to 30% to the natural dry weight of chopped straw, the fibers were loosed, and the wafer strength increased. This process showed the effect of alkali treatment. With regard to beating treatment, the beaten straw treated with similar concentrated alkali showed the multiple effect with mechanical (beating) treatment.<br>5. Sulphidity was indicated as the effect of the coexistence of sodium sulfide and sodium hydroxide. Sulphidity of 0% had high solvent power. As the effect of beater, fiber length was decreased rapidly.<br>6. The levels of factors showing good effects upon the wafer strengths and digestibilities were sulphidity of 50%, beating number (Bn)=1, and additives of flour. The order of wafer density (=ρ) value due to additives or binders was as follows: flour≥molasses>brewer's grains>citrus pulpy>rice bran. The ρ value was 1.06g/cm³ for flour added and 0.61g/cm³ for rice bran.<br>7. When chopped straw was treated with sodium hydroxide, beating treatment improved digestibility significantly. These treatments were necessary to obtain digestibility of 70%. The additive of 2 to 10% by weight of flour, molasses, brewer's grains and citrus pulp increased digestibility up to 60 to 65%.