US1138596A - Deinking process. - Google Patents

Description

0. C. WINESTOCK.

DEINKING PROCESS. APPLICATION FILED IIIAY 29. I9I2.

1,138,596., Patented May 4, 1915.

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- a 6W5/@M b InverItor n. Y I Attorneys Witnesses ETE STATES PT risica.

OTTO CHARLES WINES-TOOK, OF PERKINSVILLE, VERMONT, .ASSIGNOR TO THE GENERAL VASTE-PAPER RECOVERY COMPANY, OF BALTIMORE, MARYLAND, A CORPORATION OF DELAWARE.

DEIN KING- PROCESS.

arsenale.

Specification of Letters Patent.

Patented May d, 1915.

To all whom t may concern .llo it known that I, Or'ro G. WiNns'rocK, citizen of the United States, residing at i-erkinss-'ille, in the county `of Vindsor and Sta te of Vermont, have invented a new and,

useful Deinking Process, of which the following is a specification. i

This inyention relates to a process for deliberinfv either printedor imprinted paper `and for removing the ink from print paper.

The general principle of my process of deinking and de-ibering printed paper will he understood from the following description.

he desideratum in this art is to reduce the printed paper to an ink-free pulp without shortening, weakening or discoloring the .fibers which were'felted together to form the original paper. The approximate fulfilment of these conditions requires that the fibers be disentangled or de-felted with the minimum amount of cutting or breakage, and lthat the removal of the ink/be accomplished without exposing the paper to such prolonged `boiling or soaking in strong alkali or other material as'will rot or weaken or discolor the fiber. In searching for a proccss and means for carrying it out which shall approximately meet the above conditions, I have found that certain principles hitherto undiscovered, are essential and constitute the necessary basis for success. These .will tiret be stated broadly and afterward I will specify in detail the exact conditions 'and apparatus with which I have achieved the AQiratest measure of success.

I have foundthat when wet paper printed in ordinary black ink is torn, any ink which ou the line of tear is much loosened by the pulling apart of the paper fibers, so that the adhesion of such portions of the ink as remain on the fringe of disengaged fibersl at the torn edge is much less than the normal adhesion ofv ink to untorn paper, and it became my aim to find a cheap and practical mechanical method of shredding or tearing the paper into such fine bits -that the paperfiber foundation to which each particle of ink' adhered would be wholly or partly pulled apart, thus putting the ink in condition for easy removal by a simultaneous or even a subsequent treatment much less pro-v longed and severe than would be necessary if this foundation were undisturbed. 'The ideal accomplishment of this aim requires nearlyconiplete defelting or disentangling of the fibers of the paper; and while I recognized at first that it might not be possible to fully realize this ideal I have worked toward it and found that the means herein described and specified and forming the subject of my co-pending apparatus application Serial No. 700,546, filed May 29, 1912, accomplished it to a surprisingly complete extent. I have found that the best results are achieved 'by treating the paper during the time of defelting or disintegration with the chemical agents, or detergents, adapted to further loosen and to carry away the ink rather than byso treat-ing it subsequently. It will be seen in the detailed description of my apparatus that the loosening action on the inl: due to pulling the fibers apart is aided by mechanical attrition by the machine which tends further to mechanically remove the ink, and this doubtless accounts in some measure for the better results achieved when the detergent is present during the process of defibering so that full advantage is taken of this mechanical attrition. I have found that a relativelyT mild chemical agent and a temperature only moderately high is all that is necessary for accomplishing the removal ofthe ink whenused in this way. The detergent which I use is in general a soap containing some sodi-,um silicate and preferably some free alkali.

The requirements for tearing paper, crudely stated, are that the paper should be held at two or moreplaces and pulled apart. So long as the paper is not reduced to pieces below a certain size, this is eX- tremely easy by the useof mechanical eX- pedients which readily suggest themselves but when itbecomes necessaryto approximate at ali closely the above defined ideal conditions which Ihave set out to fulfil, the difficulties materially increase. It is of course possible to accomplish the defibering in the well known beating engine or jordan, but I have found that these or equivalent devices not only require very many times as long as does my apparatus, but also tend to vtgrind the ink into the fiber of the paper so that theloosening action, due to tearing and defibering is almost wholly nullified and offset. There is also always a. -tendency in lthese machines to cut and shorten the fiber.

Some of thefso-called digesters used in the art do not employ such close contact be-k Yso tween the moving and stationary mechanical members as that in beaters and jordans and these are therefore not open to the same objection of pounding or pressing the partly loosened ink. particles back into intimate contact with the fiber, but on the other hand they do not reduce the average size of torn particles to anything approaching the smallness which is desired, and in consequence relatively large portions of ink still remain on an unshaken and undisturbed mat of fibers and require for their removal the same drastic chemical processes that are required for larger pieces of paper.

In my apparatus I have abandoned the idea of holding the paper mechanically 1n the ordinary sense of' the Word, and I depend upon the principle which I believe to be broadly new in this art, of holding the paper while it is torn or shredded, through dependence upon its inertia', aided by the inertia of a fluid medium such as a liquid with which it is surrounded and in which it is suspended.

- time available in which it may respond to 'this force. In conformity with this general law of physics, I find that a slow moving blade or equivalent striking upon a piece of paper invested or embedded, so to speak, in a liquid, will tear that paper only if the size of the piece is relatively large, while if the piece is relatively small it will take up the motion of the blade or else be brushed or swept aside by it without being torn or perceptibly strained; that as the relative speed of the blade increases, the minimum piece that it will tear becomes of less and 'less size; and, finally that if the speed is very high a very small piece of paper 1s unable to take up this speed soon enough to avoid being torn apart. I have found that speed can, within practicable limits, be carried to such a point that a piece of paper consisting of only a few fibers Jelted together, held or restrained but backed by the inertia of the liquid in which it is immersed, can be successfully torn apart and reduced to a condition so near that of its component single fibers as to meet very closely the criterion for ideal results which I have laid down in a paragraph above. It would indeed be theoretically possible to get a speed of blade and a sharpness of edge so great that a single component fiber floating alone would be divided, but this is obviously carrying the principle to an undesirable extent. The action upon the material is in the nature of a pull or strain due to opposed tendencies or influences, and these op posing tendencies `or influences or conditions I have for convenience termed forces serving to.

lbecome clear by a reference to the figures and drawings forming a part of this specification.

Referring to thel accompanying drawing- Figure 1 is a vertical section throughy my apparatus. Fig. 2 is a vertical section on the line 2-2 of Fig. l.

The machine is suitably supported upon legs or standards l. The paper to be defibered and de-inked vis introduced into the machine through an entrance opening 2 provided with a cover 3. The opening 2 communicates with a supply chamber Il which preferably is tapered toward its lower end, as indicated'at 5, and communicates with one end of a horizontally extending pipe or draft-tube 6. Communicating with the opposite end of the draft-tube 6 is an upwardly extending pipe or return passage 7 which is gradually flared or increased in size in an upward direction. The pipe or return passage 7 at its upper end is continued horizontally as shown at 8 and extends into the supply chamber 4, and has its discharge end directed downwardly. The direction of fiow of material through the machine is indicated by the arrows.

Extending axially through the draft-tube 6 is an overdriven propeller shaftA 9 mounted in suitable bearings 10, and havingI fixed thereto, within the pipe G, one or more propellers or agitating elements 11-1'2. The shaft 9, on its outer end, is provided with a belt wheel or other driving 'means i3 capable of attaining great velocity. In the machine illustrated, the propeller blade l1 is inches in diameter and the second propeller 12 located about 13 inches away from the prtpeller 11, is about 6?-,- inches in diameter.

The draft-tube 6 is about 7 inches in diameto them and throwing it with some violence forward in the direction of the flow. This Under of as engaging with the edges of the propeller, are pulled out, thus defibering the paper Without materially shortening the fiber While at the same time, loosening the ink as before explained. The propeller subserves the secondary function of producing rapid circulation of the material Without the necessityof using a pump or other auxiliary means for this purpose. ,y

I prefer to rotate the propellers at around 1800 to 2500 revolutions per minute. It Will be observed that the mixture of Water and pulp, after being cavitated by the propellers, j

rapidly traverses the return passage 7;8 and is discharged into the supply chamber 4, from which it passes down again to the suction side of the overdriven propellers.V

The speed of rotation of the Water and stock in the machine is very rapid, approximating 1200 feet per minute. It- Will be observed that the Water and stock are carried through the -propellers and cavitated time and time again at an exceedingly high rate of speed. Actual tests have demonstrated that the machine illustrated, operating'on the inertia and cavitating principle, is very Well suitedv to the purpose of carrying out the'process of this invention, and .that it will completely defiber the stock and deterge the ink in a period of from approximately11; to 10 minutes, according to the character of the paper acted upon. In addition to the defelting action which takes place at the face of the propeller-s of my machine by theopposed action of the pfropellers and the inertia. of the stockand liquid, I believeuthat further defelting action is 'due to the velocity at Which the stock is thrown through the cavities'produced by the propellers. The hydrodynamic action of the liquid and stock as it strikes the corners of and is driven through the return tubes 7 and 8 also has a defelting-action, due I believe to the fact that the fibers on the outside of the moving mass of Water and stock are retarded by frictional contact with the walls of the return tubes, While the fibers at the center pass on more rapidly. The Waterfall effect at the discharge end ofthe tube S also has a separating or defelting effect.

,In carrying out the process on a commercial scale, larger machines than that heretofore employed me Will be used, and some of the proportions may be varied Within broad limits.l

In carrying out my process with so-called` book paper or old magazines in a machine, such as is shown in the accompanying drawing, I prefer use about 15 pounds of papers, which re torn up by hand into pieces several inches square. "Ihis paper is placed in any suitable charging tank filled with Water of a temperature, preferably of approximately 16()o F., and is permitted to remain there until the de-bering machine is ready to receive it, after which the Water and paper in the charging tank are dumped into the chamber 4 of the de-fibering machine. I prefer to permitthe paper to remain in the' hot Water in the charging tank for from 5 to 10 minutes, but this operation can be varied. Any desire-d quantity of ivarmyvater can bev used in the charging tank, so that the paper Will be softened thereby.l If a relatively small quantity of Water is used inthe charging tank, a proper amount of Water may be put into the defihering machine, so that when the softened paper is fed to the dc-fibering machine, the proportion of paper or pulp to the Water will be approximately 15 pounds of paper to about 38 gallons of Water, which corresponds to about 2O pounds of Water to about one pound oifdry paper, althoughl it will be understood thatthese proportions can be Widely varied. The Water in the de-ibering machine is preferably heated to a temperature of. approximately 160o F. This temperature seems to produce the best results, but can be varied. After the de-fiber ing machine-has been charged With the Water and paper or pulp, as before described, the deterging compound is added; This compound is described fully hereinafter. After charging the machine, as above described,

the blade-s or propellers are operated preferably at about 1800 to 2500 revolutions per minute. I have found in practice that the usual time for reducing ordinary magazine paper is aproximately three minutes, the Water and' pulp repeatedly circulating through the machine at a speed of approximately 1200 feet per minute. As before stated, with some kinds of paper, such as newspaper, the operation consumes less time and with other types of paper it may consume more. At the end of the operation the machine is stopped and ,the Water andl stock are drawn off through the outlet 15 at the bottom and placed in an ordinary paper making beater Where the pulp is Washed, in

either hot or cold Water, as desired, by incansing stock may then, if desired,.be run through a Jordan machine to brush it out and may then be conducted to the stuff chest and on to the paper machine.

I have made an excellent quality of book paper from my recovered pulp without the addition of any new stock, although in paper making practice, it may sometimes be desirable to add a small percentage of new stock. v

In carrying out the process, on printed newspaper, the operation above described is carried out in the manner described. The news pulp after being reduced in the manner described and then washed in water is found to be of substantially the same color as would be given by a mixture of ground wood and unbleached sulfite. The proportions of ground wood and unbleached sullite ordinarily used in newspaper stock are 75% of ground wood and 25% of sulfite.

The paper which I have made from my recovered book and magazine and newspaper stock is of excellent color, strength and appearance.- The recovered fiber, in fact, can be worked' back into papers very similar to those from which the fiber is recovered. Newspaper which I have made from my recovered news pulp shows strength which is substantially the same as that of the original paper, from which the fibers are recovered.

Experiments which I have conductedha ve indicated that one pou/nd of book paper will yield about lQ-g ounces of recovered pulp which corresponds to 80% yield or 20% loss, and that onel pound of newspaper will yield about 14 ounces of salable pulpior a .yield of about 87-.% or a. loss of 121-70.

It will be observed that the lower pipe or draft-tube in which the propellers are mounted is comparatively small in diameter in proportion to the courses of the remainder of the machine. By using this small drafttube, I secure a great reduction in power and provide a very efficient means of bringing all of the stock into working relation to the over-driven propellers.

While my process may be carried out by placing the print paper first in the chargtank to soften it and then feeding it into myde-iibering machine, it will be understood that said process can also be carried out by feeding the paper in dry condition directly to the de-bering machine.- In

feeding the paper dry, I prefer to shred thesame before feeding it to the de-fibering machine, although it' can :be roughly torn into piecesand fed in that condition .to the de-ibering machine.

I have found it advantageous to4 use-moreA than one propeller in the draft-tubel and xsincethe water delivered from the first propeller has Aa whirling motion, albeit at an angular velocity muchrless rapid thanthat of the propelleritself, it is advantageous to have thefsecondfpropeller of a greater pitch Lother than the first' so as to preserve roughly the same relative angular velocity between the blades and the water. v

Since the de-fibering and de-inking are coordinately important, and in my preferred form tal-:e place at the same time, it became necessary to study the conditions most conducive to the latter as well as the former. I have found that de-inking is best accomplished when the amount of water is fairly large relative to the amount of paper. There is a great deal of latitude and some difference depending upon the kind of stock employed and the kind of detergent used, but a fair average working figure is, as previously indicated, 20 parts by weight of water, to 1. part of weight of dry paper. So far as the de-ibering is concerned, the machine will run perfectly well with materially larger proportions of paper but I have found that with concentrations much greater than that named, the whiteness of the pulp becomes progressively less. I have tried smaller degrees of concentration up to several hundred partsof water to one of paper but I find there is a limit beyond which no material advantage in the cleanliness of the product is obtained and the eX- pense of the process is disproportionately increased both in the item of power and of detergent per unit of finished material.

In the matter of' detergent, assuming that the proper ratio of water to dry paper is employed, I have given a good deal of attention to determining the percentage of dry detergent by weight required for dierent sorts of paper. It is my present practice to use about 4% on old newspaper, 45% on magazine and book stock. If a larger amount of water relative to the pulp is used, the amount of detergent must be increased so as to keep the concentration suflieient, but if the amount of water relative to the pulp is diminished, the amount of detergent preferably should not be proportionately diminished since with the relatively insufficient amount of water, the concentration of this material should be somewhat greater in order to get a clean product. I herewith give a formula for detergent which has, all things considered, given the very satisfactory resultsz--QO pounds of water, 2 pounds of causticpotash, 2 to 3 pounds of tallow or suitable saponifiable material, 3 pounds ofsilicate of soda, 2 pounds of chlorid of alumina, 4 pounds of 58% alkali dissolved in 4 pounds of boiling Water.

Relatively small departures from the preferred formula specified above, produce but very slight changes i'n,V the result, but the formula as vgiven may be taken as representing the material which I have found quite satisfactory. It is interesting to note in this connection that the mechanical de-fibering and attrition alonecau'ses the loosening of a considerable percentage of the ink evenl when no detergent is employed, a circumstance which bears outrmy theory that the rapid and violent mechanical actionin this case is a powerful help to the chemical one. I suppose this to be due to the fact that dried black ink is physically a species of film or incrustation stuck to the paper ,by the adhesive elements in the ink, but capable of being mechanically loosened by relative motion or separation of the wet matted fibers to which it is stuck, as distinguished, for example, from a dye which enters into and stains the liber.

Black printing ink consists usually of a pigment and a fatty acid-or resin or oil as a'vehicle, this/vehicle carrying the coloring pigment, which in the case'of black ink, is

usually free carbon.V The effect or purpose of the detergent in my process is to saponify the fatty vehicle, which then goes into solution, leaving the particles of pigment free from the vehicle. y

The ink liberated from thepaper or pulp is mixed throughout the pulp and tends .to float to the top, carrying with it the carbon which has been freed. The ink residue, to-

` `ether with an filler ormincral matter or size, starch, etc., which may have been contained in the original paper., are washed from the stock as previously described during the washing operation whichfollows the cle-libering and de-inking operation.

In accordance with the provisions of the patent statutes I have described the principle of operation of my invention together with'what I consider the best mode of carrying out the process, but I desire to have it understood that the apparatus is only illussimilar materials consisting in immersing the paper in a liquid and feeding this through blades wholly immersed in the liquid and revolving so rapidly that they are able to break down to its component fibers small pieces of paper fed to them and held relatively against the tendency to ,revolve at the speed of the blades by their own inertia and that of the liquid in which they are suspended.

3. A' process of debering paper and like materials which consists in immersing the paper 'in a liquid and feeding this liquid through a screw propeller revolving so rapidly that it is able to deliber small pieces of paper held against the tendency to revolve with the propeller solely by their own inertia and that of the surrounding liquid.

4. A process of deibering paper and like materials which consists in immersing the paper in a liquid and feeding this through a screw propeller immersed in said liquid, revolving so rapidly as to produce a cavity in the liquid effective to promote the deibering action.

5. A process of deliberingA and deinking paper and like materials-which consists in immersing the paper in a liquid containing a detergent, and pulling apart lthe fibers of the paper by an opposition of forces acting completely below and away from the surface of the liquid, one of which forces is the inertia of the paper and the liquid in which it is suspended.

6. A process of de-ibering and de-inking print paper and like material, which Consists in softening the paper, then mixing it with a. relatively large amount of water containing an emulsifying agent, repeatedly subjecting themixtu're to the action of overdriven propelling and agitating elements wholly immersed in the liquid, and subsequently' washing the stock.

7. A process of de-libering and de-inking printed paper, which consists in immersing the paper in a relatively large amount of liquid containing a detergent, circulatingv the material by means of fast driven propeiling? agents so that the current of said material on its return passage is subjected to constrictive effect alternatively with subjection to Yexpanding effect, and in its coursepassing the liquid through a fiaringvpassage, and finally washing the stock.`

In testimony that I claim the foregoing as my own, I have hereto affixed my signature in the presence of two witnesses.

OTTO CHARLES lVINESTOCK. yWitnesses:

FRANCIS E. GALLAGHER, PERRY BAKKER.

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