US PATENT SUBCLASS 162 / 25
.~.~ With additional chemical treatment before start of defibration

Current as of: June, 1999
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162 /   HD   PAPER MAKING AND FIBER LIBERATION

1  DF  PROCESSES OF CHEMICAL LIBERATION, RECOVERY OR PURIFICATION OF NATURAL CELLULOSE OR FIBROUS MATERIAL {33}
24  DF  .~ Chemical treatment after start or completion of mechanical defibration {1}
25.~.~ With additional chemical treatment before start of defibration

DEFINITION

Classification: 162/25

(under subclass 24) Processes in which the fibrous material is also subjected to a chemical treatment before the start of the defibering process.

(1) Note. The chemical treatment prior to the mechanical defibration step is necessarily separate and distinct from that following the start or completion of the defibration, but may employ the same chemicals and conditions of treatment.

SEE OR SEARCH THIS CLASS, SUBCLASS:

26, for processes involving simultaneous chemical digestion or treatment and mechanical defibration of the fibrous material.