Abstract: A method and apparatus provide for the bleaching of mechanical pulp in such a way that the brightness of the mechanical pulp can be increased up to about 7-10 points. Mechanical pulp directly from a secondary refiner is separated, as by first and second centrifugal separators (cyclones), into a fines fraction and a fiber fraction. The fines fraction is under about 200 mesh. The fiber fraction is mixed with hydrogen peroxide (H.sub.2 O.sub.2) and subjected to displacement bleaching, which uses a minimum about of bleaching chemical to obtain the maximum brightness. The fines fraction is mixed with hydrogen peroxide and subjected to non-displacement bleaching. The fines fraction is between about 10-20 percent of the total feed pulp stream. After bleaching, the fines and fiber streams can be recombined before passage to a paper products production machines.

Abstract: A high-strength, high-yield sulfite-modified thermomechanical pulp is formed by subjecting lignocellulose to multistage mechanical attrition, the first stage being conducted at elevated temperature and pressure and the second stage being run under atmospheric conditions. A sulfite chemical is added to the lignocellulose prior to the second stage, the lignocellulose being sulfonated so that a percent bound sulfur level of at least about 0.15% is provided. A novel linerboard composition is unexpectedly produced employing replacement quantities of the above described pulp.

Abstract: A process for producing organic acid esters of cellulose, in an efficient and rapid manner, which includes confricating cellulose in the presence of esterification chemicals, the confrication step providing the major driving force in conducting the esterification reaction.

Abstract: A pulsed arc welding system is disclosed in which improved performance is obtained through the use of positive switch control in the welding transformer secondary winding. The switch means is programed through solid-state gate drivers which are in turn controlled for controlled rectification on each half cycle by a phase control, the operation of which is initiated by sensing the secondary winding voltage. Thus, it is possible to accurately control a high current interval and a low current interval with precision to obtain optimum welding and weld control.The time intervals for high level and low level welding current are also precisely controlled through digital counting techniques which permit a full range of control from zero to one hundred per cent high current mode of operation and a high current period as well as a low current period varying from 1/60 to 1-4/5 seconds.