High yield, low cost cellulosic pulp and hydrated gels therefrom

• US 4,087,317 A
• Filed: 08/04/1975
• Issued: 05/02/1978
• Est. Priority Date: 08/04/1975
• Status: Expired due to Term

• Current Assignee: Eucatex S/A Indãºstria E Comã©Rcio
• Original Assignee: Eucatex S/A Indãºstria E Comã©Rcio
• Inventors: Roberts, James R.
• Primary Examiner(s): Bashore, S. Leon
• Assistant Examiner(s): Alvo, Steve
• Application Number:
  US05/601,419
• Time in Patent Office: 1,002 Days
• Field of Search: 162/23, 162/25, 162/24, 162/26, 162/28, 162/90, 162/70, 162/187, 106/204, 106/123 LC
• US Class Current: 162/23
• CPC Class Codes: D21B 1/12 by wet methods, by the use of steam beaters D21D1/00
• CPC Class Codes: D21C 1/10 Physical methods for facilitating impregnation
• CPC Class Codes: D21C 3/02 with inorganic bases or alkaline reacting compounds, e.g. sulfate processes

Abstract

Cellulosic pulp is made in 85% yield by mechanically defiberizing lignocellulose in a steam atmosphere, mixing the resulting aqueous fibrous pulp with a lignocellulose-pulping quantity of finely divided lime, and digesting the pulp in the presence of the lime to a predetermined degree of pulp digestion. The resulting digested fiber can then be mechanically beated in aqueous medium until it is substantially converted to a hydrated cellulosic gel product.

Claims

1. The process of making high yield low cost cellulosic pulp which comprises:

(a) mechanically defiberizing lignocellulose by mechanically abrading lignocellulose pieces in an atmosphere of steam at a pressure of from 100 to 170 psi and corresponding temperatures for saturated steam for a time sufficient to reduce the lignocellulose to a fibrous product having a Clark classifier fiber size of less than 10% plus 12 mesh,

(b) mixing with the fibrous product from 1% to 20% by weight, dry fiber basis, of lime,

(c) adjusting the consistency of the resulting mixture of aqueous lignocellulosic pulp and lime to a consistency of from 10 to 25%,

(d) digesting the fiber to pulp form in the presence of the lime to a final pH of from 6 to 8 at steam pressures of from 75 to 125 psi and corresponding temperatures for saturated steam for a digestion period of from 30 to 90 minutes to digestion temperature and from 5 to 60 minutes at said digestion temperature, and

(e) mechanically beating the resulting digested fiber in aqueous medium until it is substantially converted to a hydrated cellulosic gel product.

2. The process of claim 1 wherein the lignocellulose is defiberized in a first stage to a Clark classifier fiber size of less than 20% plus 12 mesh and in a second stage to said Clark classifier fiber size of less than 10% plus 12 mesh.

3. The process of claim 1 wherein the fiber is mixed with from 5 to 15% by weight, dry fiber basis, of finely divided lime.

4. The process of claim 1 including the step of hydrapulping the digested fiber for a time sufficient to break up fibrous clumps and open up and separate the component fibers of the pulp.

5. The process of claim 1 wherein the lignocellulose is wood.

6. The process of claim 1 wherein the lime is added as milk of lime.

7. The process of claim 1 wherein the lime is mixed with the fibrous product during the final stages of the defiberizing operation.