Rehydration of once-dried fiber

• US 5,925,218 A
• Filed: 03/03/1997
• Issued: 07/20/1999
• Est. Priority Date: 03/03/1997
• Status: Expired due to Fees

• Current Assignee: Westvaco Corporation (Meadwestvaco Corporation)
• Original Assignee: Westvaco Corporation (Meadwestvaco Corporation)
• Inventors: Ogden, Roger Wayne
• Primary Examiner(s): Chin, Peter
• Assistant Examiner(s): Leavitt, Steven
• Application Number:
  US08/808,905
• Time in Patent Office: 869 Days
• Field of Search: 162/4, 162/24, 162/52, 162/68, 162/191, 162/63, 162/9, 162/187, 162/100
• US Class Current: 162/191
• CPC Class Codes: D21C 3/00 Pulping cellulose-containing materials digesters D21C7/00
• CPC Class Codes: D21C 5/02 Working-up waste paper mechanical part D21B1/08, D21B1/32
• CPC Class Codes: D21C 9/00 After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere polysaccharides, derivatives thereof C08B; paper-making D21B - D21H
• CPC Class Codes: Y02W 30/64 Paper recycling

Abstract

This invention relates to the rehydration of once-dried fiber for use in a papermaking furnish. Such a rehydration of this type, generally, employs temperature, pressure and refining to make the once-dried fiber behave more like a virgin fiber. Thus, higher levels of once-dried fiber can be used without sacrificing paper formation, surface smoothness, and productivity (drainage).

Claims

1. A method for rehydrating and increasing the water retention value of individual once-dried fiber lumens, wherein said method consists of the steps of:

placing a fibrous furnish prepared from dry broke having individual once-dried fiber lumens within a digester means;

combining a predetermined amount of water with said broke furnish within said digester means wherein said predetermined amount of water and broke furnish is at a water-to-fiber solids ratio of greater than 5;

1;

gradually elevating a temperature of said digester means to turn said water to steam;

cooking said broke furnish/steam mixture in said digester means at a predetermined cooking temperature for a predetermined time, such that said individual once-dried fiber lumens become substantially rehydrated and a water retention value of said individual fiber lumens is increased;

opening said rehydrated fiber lumens; and

dewatering said rehydrated individual fiber lumens to a predetermined consistency of approximately less than 30% solids.

2. The method, as in claim 1, wherein said cooking temperature is approximately 130-150°

C.

3. The method, as in claim 2, wherein said predetermined cooking temperature is approximately 145°

C.

4. The method, as in claim 1, wherein said temperature elevating step is further comprised of the step of:

gradually elevating said temperature of said digester means for approximately 45 minutes.

5. The method, as in claim 1, wherein said predetermined time in said cooking step is approximately 60 minutes.

6. The method, as in claim 1, wherein said predetermined consistency is approximately 20% solids.

7. The method, as in claim 1, wherein said predetermined amount of water and broke furnish is at a water-to-fiber solids ratio of approximately 10:

1.