US1717798A - Process of making pulp - Google Patents

Description

Penman: 18, 1929.

UNITED STATES I 1,717,798 PATENT o1=1=1c1-:.

ROBERTA. MARE, OF NORFOLK, VIRGINIA.

PROCESS OF MAKING- PULP.

Io Drawing. Application filed latch 27, 1924, Serial No.v 702,442. Renewed March 15, 1929.

The present invention relates to the production of pulp and pulp roducts from wood and other cellulosic an ligneous material, and the process is applicable to all 8 kinds of wood, including woods that are hard, soft, porous, non-porous, also other equivalent materials e, g. cane, bamboo, straw, sedges and other marsh growth, banana stalks, cocoanut husks and the like.

The process consists essentially in first boiling the wood in a solution containing sodium nitrate or other nitrate of an alkaliforming metal, such as potassium nitrate, calcium nitrate, magnesium nitrate, although other nitrates can be employed, and it is not by intention to restrict the present case to the use of a particular nitrate or a group of such nitrates. However, the nitrates of the alkali-forming metals are enerally cheaper and somewhat more satis actory than an other nitrate with which I have experimented. After the material has been in the solution of nitrate, the same is removed from the solution, is preferabl soaked for a time in coldwater, after whic it is run through pressure rolls or otherwise crushed and is then run throu h a pulper, with water, and is then preferab run into a beater in which it is beaten, pre erably with the roll raised a substantial distance above the bed-plate, (3 to 5 turns) after which it may be sheeted or a ortion of the cementitious matter ma first be removed from the pulped materia either before, during or after the beatin operation, before being converted into s eets. The pulp can be produced converted into sheets in the form of paper or cardboard or it can be converted into other shaped articles, in a manner well understood in the art.

is to be understood that they are .given merely for the purpose of illustration and not as restrictin the invention thereto.

Ewample 1.-- looks of spruce in a dried say 40% of water, and blocks of yellow oplar were introduced into a digester sue as is used in making pulp by the well known processes, includin the soda process, sulphite process and t e like, suflicient of the solution being used to completely cover the woody material. The mass was then heated until a pressure of about 110 lbs, existed in the digester, which condition was continued for about an hour, after which the solution was allowed to cool more or less and The following examples are given, but it.

condition, chips of spruce containing about the material removed from the digester. The total time that the pressure was above 80 lbs. in the digester was considered as the effective cooking period, this amounting to two hours.

The treated material was then removed from the digester' li uor, was placed in a tank of cold water, 'or several hours and the materials were then run through crushing rollers, then with water through a pulper, and into a beater. The beating was commenced with the roll of the beater raised about six turns above the bed, and the roll was gradually lowered to about 3 turns of the bed. The beating was continued for half an hour, after which a portion of the pulp was sheeted and-dried Without washing. An-

other portion of the pul was first washed, being given a light was ing, with a spray of water, and was then sheeted. Another portion was further beaten for half an hour and sheeted. Another portion was further beaten for half an hour, at about the end of the beating operation, size and alum were added in the amounts commonly used in sizing paper. In other instances portions of the pulp were washed and then sized, and then sheeted.

Ewample 2.-Blocks of spruce wood, in a substantially air dry state were placed in the liquor remaining from the above treatment, and heat applied. About three-quarters of an hour were necessary before the pressure reached one hundred pounds and the pressure was maintained at one hundred pounds for about an hour, after which the liquor was allowed to cool somewhat and the blocks removed from the digester and placed in cold water overnight. The followin day these were worked up as above indicate E'mample- 3.-Blocks of air dr spruce wood, spruce wood in the form of c ips contaming about 40% of moisture, yellow poplar and green cane were placed in the solution'remaining from the above experiment my experiments indicate that the solution can be used a very great number of times before the same becomes sufliciently impureto make it necessary to discard the same. The heating of the solution, by blowing in steam, will of course dilute the solution to a certain extent, and it is accordingly advisable after each fourth or fifth cook, to add a little more nitrate, in order to bring tllie stirength back to that originally emp oye The sheeted products resulting frpm' the treatment of spruce wood were of a light but? color. All of the sheeted material produced in the above ex eriments was found to be very strong, simi ar to kraft pa er of the best grade. The product'produce from poplar wood was of a substantially darker color than that produced from spruce, being 0 a medium brown. This product was particularly strong and tough and was adapted for very strong wrapping paper.

During the cooking operation, the liquor acquires a yellowish color and is found to have a pronounced'caramel odor.

My experiments indicate that something over 95% of the dry matter of the wood can be recovered in the form of unwashed pulp, but it is to be understood that any de- 3 sired proportion of the cementitious matter can be washed out after the pulpin o eration, either before during or after t e eating operation. The cementitious matter thus washed out can be recovered and can be used in making various plastic shaped articles.

The use of nitrates seems in some respects to be somewhat better than sulfates as referred to in some of mycopending applica- 40 tions, and also seems to, be somewhat better than sodium chloride referred to in another copendlng aplpllcation of mine. From the same wood, t e pulp product produced when mtrate forms the dlgestive solution, seems to be somewhat tougher and stronger than the solution used in sodium chloride.

The ulp produced can be used not onl for ma mg paper and other similar prod ucts, but for makmg cardboard and various molded articles.

While I have above referred to the use of a solution of 1.6%, it is to be understood that the product.

It will be observed that while in many of the pulp-making processes heretofore, used 1n the country, it has been customary to boil the wood or other material under high pres- 5 sure untll the same has been converted into a pulp, and the cementitious matter has been entirely destroyed, in I the process of the present application I preferably boil only until the cementitious matter has been converted into a readily friable condition so that the material can be readily crushedby being run between heavy rollers, or by bemg treated in an edge runner mill or similar device.

I call attention to the fact that while inthe prior processes, commonly in use in this country, such as the sulfite process and the sodium su called sulfate process). I claim: Y

1. A process which comprises boiling cellulosic and li eous material with a dilute aqueoussolution of a soluble nitrate, soaking in water and mechanically reducing to process, the soda fide process (so a pulK. v

2. processwhich comprises boiling cellulosic and ligneous material with a solution of a. nitrate of an alkali-forming metal of substantially below 4% concentration, and continuing the treatment until the cementitious matter is converted into a readily friable condition but not until the material has been convertedinto a (pulpy mass, thereafter soaking in-water an ducinito a pulp.

3. process which com rises boiling cellulosic and ligneous matenal with a solution of sodium nitrate, and continuing the treatment until the cementitious matter is converted into a readily friable condition but not until the material has been converted into a pulpy mass, thereafter soaking in water and mechanically reducing to a pul mechanically re-.

4. A process which com rises boiling ce lulosic and ligneous material with a solution.

of sodium nitrate of about 1 to 4% strength, and continuing the treatment until the cementitious matter is converted into a readil friable condition but not until the material has been converted into a pulpy mass, thereafter soaking in water and mechanically reducing to a pulp.

5. A process which comprises boiling cellulosic and 1i eou's material with al to 2% solution 0 a nitrate of an alkali-forming metal, and continuing the treatment until the cementitious matter is converted into a readily friable condition but not until the material has been converted into a pul y mass, thereafter soaking in water and mec anically reducing to a pulp.

6. A process which comprises boiling cellulosic and li neous material with a 1 to 2% solution 0 a nitrate of an alkali-forming metal, and continuing the treatment until the cementitious matter is converted into i a readily friable condition but not until the material has been converted into a pulpy' mass, thereaftercrushing the cooked mate rial and mechanically pulping thesame without subjecting the same to the usual grinding operation pulp.

In testimony whereof I aflix my signature.

, ROBERT A. MARR.

used in making wood