US1310694A - Vance p - Google Patents

Description

M S WW Wm No Drawing.

To all whom it may concern Be it known that I, VANCE P. EDWARDES,

a citizen of the United States, residing at Madison, in the'county of Dane and State of Wisconsin, have invented certain new and useful Improvements in-the Manufacture' of Cellulose,-0f which the following is a specification. j

This'invention relates to im rovements in the manufacture of cellulose from any material containing cellulose and has for its chief object the production of a finished, pure product more closely resembling pure cellulose in physical andchemical characteristi'cs than any heretofore produced.

One object of the iIIVGIItlOIi is to provide j l asatisfactory process for obtaining. from Wood and vegetable growth a cellulose which can be satisfactorily substituted for cotton in the manufacture of nitrocellulose, surgical dressings, and other commercial uses. I

The process provides for the treatment of wood pulp, which has beengivenapreliml nary treatment by the sulfite process, with a secondary treatment with a weak solution of caustic soda. As a result of the treatment the pulp loses about 20% of surplus undesirable matter, the physical characteristics have changed and it is much softer and more absorbent and the fiber length has not been,shortened. The resultant pulp can be bleached with a much smaller proportion of bleaching chemical than could the untreated material.

The process may be operated more effectively and at a much lower cost than any known process. The above and other ad vantageous"featureswill be set forth in the following detailed statement of the process. In commercial practice, sulfite pulping is carried on bytwo methodsthe direct and indirect. In the first case, wood prepared in a suitable manner is charged into digesters and a suflicient quantity of acid is run in. This acid is made up by bringing sulfur dioxid gas into contact with calcium or magnesium hydroxids, or a mixture of the two, or other suitable bases and water in sufiicient quantities. The acid composition may vary within wide limits and there are a number of standard methods of preparation in use. It may contain various percentages of such bases as calcium and magnesium or any one base to the total exclu- MANUFACTURED! cELLu'LosE.

cent. total, 6

VANCE r. EDWARDES, or mnmson, WISCONSIN, nssrenon r0 THE UNITED STATES or AMERICA.

Specification of Letters Patent. Patentgdl July 22, 1919, Application filed January 18, 1319. Serial No; 271,891.

be made with acid strength varylng from 3.4 per cent, total sulfur dioxid, 1.7 per cent. free and 1.7 per cent. combined to 7 per per cent. free and 1 per cent. combined;

- The percentage of total S0 is limited by mechanical conditions of the operation.

For instance, it has been found that when Working with "an acid ofthat composition or stronger, it-is impossible, to place the cover. of the-digester onas the evolution of gas caused b the contactof the acid with the heated lining of the digester is suffi cient to generate enough pressure to blow off the cover. a

The temperatures, pressures, and methods of cooking may also vary, not only with the acid used but with the judgment of the operator. Forth'e quick cook, steam is admitted into the digester and pressures of to 90 lbs., with maximum temperatures from 125 C. to 165 C., are carried for 5 to 12 hours, with a total cooking time varying from 6' to 14: hours. When the cook is completed, the pulp is. discharged under pressure from the digester,'usually into a blow pit where it is drained and washed.

The indirectcook is made much after the same manner, although, as the name implies, no, direct steam is used, the heat being supplied by steam coils in the digester. The

,wood, in general, is prepared in the same manner as for the direct cook although the chips are usually longer. In this process it is quite common to rotate the digesters in order to secure better circulation. T he acid used here is much weaker than the average practice in the direct cook and-will analyze as low as 2.8 per cent. total S0 1-8 per cent. free and 1 per cent. combined. The

time of cooking 1s in the neighborhood of 40 hours, the maximum pressure not more than 60 lbs. and the maximum temperature about 135 C. It is quite common to steam the wood before admitting acid. Usually the pulp isnot discharged under pressure as in the direct cook. but the pressure isrelieved, the,liquor blown off and then the pulp discharged. There are also c ombinations of these two processes, in which both direct and indirect steam is used. Var1ations in .the process may be made according tothe conditions surrounding the'operation' of the process in the mill.

sion of the other. Satisfactory pulp may For nitration work, chemical rather than physical qualifications are the desideratwm.

The most important of these is measured by the solubility of'the material in a solution of potassium-hydrokid under definite conditions." Unbleached sulfite pulp contains from 1 18-30% and bleached sulfite pulp contains 30. :Q%, of potassium hydrbxid. soluble matter which-by the alkaline digestion may be reduced to almost any figure desired, de-

pending upon. the treatment employed.-

J After treatment, the pulp is very. readily bleached with the consumption of far less chemicalsthanj the untreated pulp.

.The practicein commercial sulfite pulping j isto reduce the wood as thoroughly as pos sible, leaving very small percentagesfof undercooked material. In such a case the yield is in the neighborhood of 43%.

This pulp loses 20% .or more'when given the secondary "alkaline treatment, .thus. re-

' manner is so treated as to, give a uniformly raw cook. By that is meant that the pulpducing the finalyield in alike proportion,

.and the following modification to the process has been successfully carried out:

Wood prepared for-pulp1ng in the usual ing process is not-wholly complete. The

- and temperatures to be used vary with they yield in sucha case will be: 50% or over and consequently the final yield, after the caustic digestion, greater'than if thoroughly cooked pulp had been-used. The pulp is separated" from the liquor and is now ready for the secondary alkalinetreatment of'the invention. The pulp-is cookedin a closed vessel or digester with from 5 to 15 percent. of its weight of caustic soda in solution, the strength of which may vary from {to 2 per cent. and the ratio of the weight of liqu or to the pulp-may vary from 6 to 1 and from 12 to 1. Various concentrations and O volumes ofsodium hydroxid solutions may 1 beused. Good results with wood pulp are to 45-.

be had by using a solution of 10% and about 10% concentration, that is, for every 100 grams of pulp,-1O grams of sodium hydroxid made up toIOOO c. e. werev used. Pressures quality and kind'of the pulp used and the quality ofthe pulp desired. The pressure 3 and temperature within the closed vessel may be controlled as desired. The process may be conducted at a pressure of 1.0 pounds and. with a temperature of about 115 (3..

A satisfactory operation of the process has beenconducted with a pressure of 50 pounds -and a-temperature of about 148 C.

of the solution, care must be taken not to .perature of at least 115 C.-

Regardless of the strengthv make the treatment too drastic. In such a case appreciable quantities of cellulose will be dissolved by the caustic and excessive loss occur. By properly regulating the severity of the treatment, this loss can be reduced to a minimum.

g It is known that eflorts have been made to use a subsequent treatment of caustic soda on a sulfite pulp. All such suggested processes now known are chemically wasteful, using many times the amount of chemicals used in the present process, and are not practicable mechanically. Emphasis is directed to the low chemical consumption of this process, the fact that the sulfite pulp is undercooked, and -to the operation of the process under very considerable pressure, for

a relatively short time.

Without any further treatment, paper made from pulp which has been treated in the manner-indicated inall 0f the foregoing is very soft and absorbent,.is in a condition suitable for the manufacture of nitrocellulose, though. possibly a slight bleachin treatment may be necessary, contains no fluff and has other properties which point to its adaptability as a surgical dressing. In addition to the two uses mentioned, others will suggest themselves, particularly where soft, bsorbent material can be used.

What I claim is 1. The process of producing cellulose which comprises treating fibrous vegetable material with acid sulfite liquor, separating the fibrous material from the liquor, treat-- ing the fibrous material with a solution of caustic soda, and subjecting it to' a pressureof at least ten pounds and to a tem- -2. The process of producing cellulose which comprises treating fibrous vegetable material with acid sulfite liquor, separating the fibrous material from the liquor. treating the fibrous'material with "a solution of'caustic soda of %-2 percent. strength and constituting 5-15 per cent. of the weight of the fibrous material, and subjecting the mixture of fibrous material and caustic material to a pressure of at least ten pounds .and a temperature of at. least 115 C. s

3. The process of producing cellulose which comprises treating fibrous Vegetable --material with acid sulfite liquor, separat ing the fibrous materialfrom the liquor, treating the fibrous material with a solution of caustic soda, and subjecting it to a pressure of at-lea'st ten pounds and to a tem;

perature of at least 115 'C., said heat and pressure treatment being maintained for at least one -hour..

4.- The process of producing cellulose whichicomprises treating fibrous vegetable material with acid su'lfite liquor, separating the fibrous material from the liquor, treating the fi'brous material with a solution of canstic soda of %-2 per centstrength and con- Stitllti Ilg 5-15 percent. of the weight of the" fibrous material, and subjecting the mixt'ure of fibrous material andlcaustic' material to a pressure ofat least ten pounds and a temperature of at least 115 0., saidfiheat and pressure treatment being ,maintaiued for one hour,

5. The process of producing cellulose which comprises treating fibrous vegetable material with vacid'sulfite liquor, separating the fibrous material from the liquor, treating the fibrous material with a solution of caustic soda constituting; 5-15 per cent. of the weight of the fibrous .materialand subjecting the mixture of fibrous material and caustic material to a pressure of at least ten pounds and :a temperature of at least 1 15.C..

.6, The process of producing cellulose which comprises treating fibrous vegetable material with acid sulfite liquor, separating-the fibrous material from the liquor,

treating the fibrous material with a solution of causticsoda and constituting 5-15 per cent. of the weight ofthe fibrous material, and subjecting the mixture of fibrous treatment being maintaihed for one hour. 1

material and caustic material to a pressure of at least ten poundsand a temperature of at least 115 C.,sa1d heat and pressure 7. The process of producing cellulose which comprises treating fibrous vegetable material with acid sulfite liquor, separating the fibrous material'from the liquor,

treating the fibrous material with a solution of caustic soda, and subjecting it to a pressure of at least fifty pounds and to a te1nperature of atleast 148 C.

.8. The. process of producing cellulose which comprises treating fibrous vegetable material withfacid sulfite liqpor, separating the fibrous material 'from the liquor,

treating the fibrous material with a solution of caustic soda, and subjecting it to a pressure greater than atmospheric pressure nd to a temperature of at least 115 C.

9. The process of producing cellulose which comprises treating fibrous vegetable material with acid Sulfite liquor, separating'the fibrous material from the liquor,

treating the fibrous material with a solution of caustic alkali, and subjecting it to a preswhich 11. The process of producing cellulose which comprises treating fibrous vegetable material with acid sulfite liquor and cooking the material so treated to an underdone condition, separating the fibrous material from the liquor, treating'the fibrous material with a solution of caustic soda of -2 per of the weight of the fibrous material, and subjecting the mixture of fibrous material and caustic material toe-pressure of at least ten pounds and a temperature of at least 115 C.

12. The process of producing cellulose which comprises treating fibrous vegetable material with acid sulfite liquor and cooking the material so treated to an underdone condition, separating the fibrous material from theliquor, treating the fibrous material with a solution of caustic soda, and subjecting it to a pressure of at least ten pounds and to a temperature ofat least 115 G.,'said heat and pressure treatment being 'maintained' for one hour.

13. The process of producing cellulose which comprises treatingfib'rous vegetable material with acid sulfite liquor, and cooking the material so treated to an underdone condition, separating the fibrous material from the liquor, treating the fibrous material with a solution of caustic soda of 4 -2 per cent. strength and constituting 5-15 per cent.

cent. strength and constituting 5-15 per cent.

of the weight of the fibrous material, and

subjecting the mixture of fibrous material and caustic material to a-pressure of at least ten pounds and a temperature of at least r 115?..(1, said heat and pressure treatment beingmaintained for one hour.

14. The process of producing cellulose material with acid s,]1lfite liquor, and cooking the material so treated to an underdone condition, separating thefibrous material from the liquor, treating the fibrous material with a solution of caustic soda constituting 5-15 per cent. of the weight of the fibrous materlal and subjecting the mixture of -which comprises treating fibrous vegetable fibrous material'and causticmaterial to a pressure ofi at least ten pounds and a temperature of at least 0:.

15. The process of 'producing cellulose which comprises treating fibrous vegetable material with acid sulfite liquor, and cooking the material so treated to an underdone condition, separating the fibrous material from the liquorjtreating the fibrousmate'rial with a solution of caustic soda and constituting 5-15 per cent. of the weight of the fibrous material, and subjecting the mixture of fibrous material and caustic material to a pressure of at least tenpounds and a temperature of at least 115 C.,' said heat and pressure treatment being maintained for one hour. 16, The process of producing cellulose comprises treating fibrous vegetable materialwith acid sulfite liquor, and cookcmaterial withacid sulfite liquor, and cooking the material so treated to an underdohe condition, separating the fibrous m'aterialfrom the liquor, treating the fibrous material with" a solution of caustic soda, and subjecting it to a pressure greater than atmospheric pressure and-to a temperature of at leastl15 C.

181 The process ofproducing" cellulosei' which comprises treating fibro'usflvegetable materialwith acid sulfite liquor, and cooking the material so treated .to anunderdonecondition, separating the fibrous material from the liquor, treating the fibrousmate? rial with a solution of caustic alkali, and

subjecting it to a pressure greater than atmospheric and to aitemperature of-at-least 115 C. I f. Y I

19. The process of; producing-cellulose which comprises treating fibrous vegetable?- .material withacid sulfite liquor, cooking the material stopping the cooking action before the pulping action, is complete, separating the'fibro'us material from the liquor, treating tic soda, and subjecting it to a pressure of at least ten pounds 'and'toa temperature of at least 115 C.

which comprises treating fibrous egetable material, with acid sulfite liquor, separating the'fibrous material from the liquor, treating the fibrous material with asolution of treatment being ,maintained for" approximately-'onehourL i I In testimony whereof I affi-x m signature;

y the'fibrous material with a solution of caus- 20. The process of producing cellulose caustic soda, and subjecting it tola. pressure v of at least fi y pounds'and to a temperature of at least 48 0., said heat'andj pressure v