US1455471A - Method of preparing pulp - Google Patents

Description

Patented ay 1 5, 1923.

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TENT OFFICE.

CARL BACHE-WIIG, OF PORTLAND, MAINE; BERTHA M. BACHE-WIIG EXECUTRIX OE SAID CARL BACHE-WIIG, DECEASED.

METHOD PREPARING PULP.

1T0 Drawing. Application filed April 27, 1918, Serial No. 231,204. Renewed December 22, 1919. Serial To (ZZZ whom it may concern:

Be it known that I, CARL BACHE-VIIG, a citizen of the United States, aresident of Portland, in the county of Cumberland and State of Maine, have invented an Improvement in Methods of Preparing Pulp, of

which the following is a specification.

This invention has-for its object the production of pulp by a novel method, from straw, corn-stalks, wood, baggasse and simiare disclosed in my Patent No. 1,327,221,

issued January 6, 1920.

l\Iy novel metliod'involies two treatments which are preferably carried on successively.

By my first treatment the cellulosic material composing the pulp is softened, that isto say, its ligneous matter is softened but not destroyed and its fibers are swollen and caused to separate.

In carrying out the first treatment I may proceed as follows :the material or ,substance employed, in small pieces, or cutinto suitable short lengths, is placed in a tank or digester, which may be open or closed, and a softening agent. a solution of sodium chloride. (NaC-l) is added, as for instance, I may add water containing from one half of one to three percent of sodium chloride; and then heat the mass to a temperature of from C; to 110 C. for from 12 to' 72 hours, the temperature and time being more or less variable depending on the materials used and the strength thereof. yet it will be understood that ordinarily the higher the temperature, the shorter the time required, and vice versa During this first treatment the ligneous matter and fiber, are acted upon and gently softened but not destroyed.

The ligneous matter may be utilized subsequently in the composition of the paper, so that the loss in weight is immaterial and the result is a very large yield. v

Moreover, the pieces are more or less saturated with the solution, which solution is further utilized in the performance of the second treatment of my method.

The solution is then drawn off or removed.

' The same solution may be used repeatedly as a softening agent for a large number of times, if desired, and in such case it becomes quite rich in potash which is extracted from the cellulosic substance sufficiently to admit of the potash being claimed by evaporation or other means for commercial purposes.

The second treatment; The mass having been thus treated is then cooked with a bisulphitepulp forming liquor, or a sodium chloride solution depending upon which kind of paper the pulp is to be used for.

For instance, when during the firsttreatment a sodium chloride solution is employed, then, during the second treatment a bisulphite liquor may be employed and pulp for a fine grade of paperwill be produced which will be suitably bleached.

The strength of the bisulphite solution will be such, together with .the time and temperature of cooking that the fiber will not be destroyed outside of the fiber walls as usually is the case in the ordinary processes.

The first treatment only softens the ligneous matter and the fiber and therefore a weak solution can be used on the second treatment thus retaining all the fiber in the material treated.

This second treatment may continue for a period of time, say from 6 to 12 hours,- at a temperature of from110 degress C. to 130 degrees C. but the longer the period of time There is a physical reaction between the softening agent, as sodium chloride, with which the mass is saturated during the first treatment, and the pulp forming agenteniployed' as the bisulphite liquor employed during the second treatment, to which I attribute, at least in part, some of the advantages gained by this process.

On account of the first treatment, as aforesaid, a weaker pulp forming agent may be employed in the second cooking operation,

and also alower temperature and a shorter period of time than under any of the methods known to me.

By this process a good news print paper may be produced with straw alone.

1.- The method of treating straw, cornstalks and other cellulosic substances for the preparation of pulp for paper which c0nsists in two successive treatments, first, treating the material with sodium chloride to soften but not destroy the ligneous matter, and second, cooking the treated mass with a bisulphite pulp forming liquor of such strength that the fiber'will not be destroyed.

2. The method of treating straw, cornstalks and other cellulosic substances for the preparation of pulp for paper which con sists in treating the material with sodium:

chloride to soften but not destroy the ligneous matter and subsequently cooking the mass with a bisulphite pulpforming liquor of such strength that the fiber will not be destroyed.

3. The method of treating straw, cornstalks and other cellulosic substances for the preparation of pulp for paper which consists in two successlve treatments, first, treating the material with sodium chloride to soften but not destroy the ligneous matter,

and to extract potash from the cellulosic substance, then drawing oil the softening agent containing the potash and then cooking the mass. v v

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing witnesses.

CARL BACHE-WIIG.

Witnessesi CHARLES DUMMOND,

WADLEIGH B/DUMMOND.