Process and apparatus for preparing a homogeneous solution of xanthated alkali cellulose

DETAILED DESCRIPTION We claim: 1.
In a process for treating a substantially completely xanthated alkali cellulose solution so as to form a homogeneous solution thereof with an alkali hydroxide solution, the improvement which comprises continuously passing a substantially completely xanthated alkali cellulose solution through a series of separate attrition and mixing stages and partially diluting said solution during each mixing stage.
2.
In an apparatus for treating a xanthated alkali cellulose solution so as to form a homogeneous solution thereof with an alkali hydroxide solution comprising a series of separate and connected attrition mixing chambers, each of said chambers having attrition means through which the xanthated cellulose solution enters into the chamber and mixing means for mixing said xanthated alkali cellulose solution with a diluent, and wherein each mixing chamber is provided with inlet means separated from said attrition means for introducing said diluent into said chamber so as to partially dilute the xanthated alkali cellulose solution in each chamber.




Description:
This invention pertains to process and apparatus for continuously xanthating alkali cellulose (AKC) and for converting such alkali cellulose into a spinnable viscose solution.
In many conventional processes for making viscose spinning solution, alkali cellulose is xanthated by contact with carbon disulfide (CS.
sub.
2) in a batch process.
Typically, the alkali cellulose is in crumb or shredded form and is converted into a sticky mass by xanthation.
Numerous efforts have been made to provide a commercially acceptable continuous xanthation process and apparatus therefor.
Examples include the processes and apparatus disclosed in U.
S.
Pat.
Nos.
2,762,795-Schlosser et al (xanthation of sheet alkali cellulose passing through a sealed chamber), 2,801,998-Robertson (conventional crumb xanthation followed by later stage involving continuous mixing in wet forms), 2,985,647-Von Kohorn (continuous xanthation of crumb), 3,385,845-Trieber (semi-continuous batch addition and passage through dry xanthation stage followed by a final wet stage), 3,438,969-Meister (xanthation in a kneader-type reactor followed by a vertical column and subsequent vertical solution-forming tower with agitator) and 3,671,279-Yasui et al (continuous kneading and passage of crumb and dough-like material)