Method for modifying a carbohydrate material

Claim 1

A PROCESS FOR PRODUCING ETHERS OF STARCH WHICH COMPRISES TRANSPORTING A MIXTURE OF STARCH AND FORMALDEHYDE CONTAINING NOT MORE THAN ABOUT 8 PERCENT OF MOISTURE IN A THIN LAYER OF FROM 2 TO 18 MM. THICK ACROSS A STRAIGHT HORIZONTALLY MOUNTED REACTION SURFACE WHILE HEATING SAID MIXTURE AT A TEMPERATURE BETWEEN ABOUT 135*C. AND ABOUT 230*C., SAID SURFACE BEING INTERRUPTED BY RIDGES EXTENDING ACROSS THE WIDTH OF THE LAYER WHICH EFFECTS A SPALLING AND CRUMBLING ACTION ON THE MIXTURE AS IT IS MOVED OVER SAID RIDGES TO INDUCE A REDISTRIBUTION AND INTERNAL MIXING OF THE STARCH AND FORMALDEHYDE WITHIN SAID LAYER, EFFECTING MOVEMENT OF SAID MIXTURE ACROSS SAID REACTION SURFACE AND OVER SAID RIDGES BY VIBRATING SAID REACTION SURFACE, SAID VIBRATIONS HAVING A FREQUENCY OF FROM 475 TO 710 PER MINUTE AND AN AMPLITUDE OF FROM 1/8 TO 1/2 INCH, AND COOLING THE RESULTING STARCH ETHER.