Ammonia-ketone pulping process

• US 3,951,734 A
• Filed: 10/11/1974
• Issued: 04/20/1976
• Est. Priority Date: 10/11/1974
• Status: Expired due to Term

• Current Assignee: Weyerhaeuser Company (Weyerhauser)
• Original Assignee: Weyerhaeuser Company (Weyerhauser)
• Inventors: Lang, Charles J., DeHaas, Gerrit G.
• Primary Examiner(s): Bashore, S. Leon
• Assistant Examiner(s): Corbin, Arthur L.
• Application Number:
  US05/514,041
• Time in Patent Office: 557 Days
• Field of Search: 162/70, 162/72, 162/90
• US Class Current: 162/72
• CPC Class Codes: D21C 3/024 with NH3 or H2O
• CPC Class Codes: D21C 3/20 with organic solvents or in solvent environment

Abstract

A method of employing the combination of ammonia and ketones as the cooking chemicals in a digester of a pulping process. This method results in a pulp which has a higher yield than the kraft process yet is characterized by kraft'"'"'s high strength and fair bleachability. The spent liquor extracts are primarily lignin and contain little cellulose and hemi-cellulose.

Claims

1. A pulping process comprising the steps of:

mixing cellulosic raw materials with an aqueous pulping liquor containing ammonia and one or more ketones;

digesting said cellulosic raw material in said liquor at a temperature of 170°

C to 220°

C and for a time of from 10 to 300 minutes with the ratio of 2 to 20 pounds pulping liquor to 1 pound oven-dried cellulosic raw material, the ammonia concentration and the ketone concentration being from 5 to 22% and 15 to 70% by weight, respectively, of the total liquor;

cooling the mixture;

separating the pulping liquor from the digested cellulosic raw material.

2. The process of claim 1 wherein the cellulosic raw material is wood chips.

3. The process of claim 1 wherein the ketone is selected from the group consisting of acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and combinations thereof.

4. The process of claim 1 wherein the temperature of the digestion step is from 190°

C to 210°

C.

5. The process of claim 1 wherein the pulping liquor ratio is from 3 to 10 pounds liquor per 1 pound of oven-dried cellulosic raw material.

6. A pulping process comprising digesting cellulosic raw material with an aqueous pulping liquor containing 10-22 weight % ammonia and 20-60 weight % ketone.