US1812832A - Filled pulp and method of making the same - Google Patents

Description

Patented June 30, 1931 UNITED STATES PATENT OFFICE HAROLD ROBERT RAITON, OF LAWRENCE, MASSACHUSETTS, ASSIGNOR TO RAIFO PROCESS CORPORATION, A CORPORATION OF MASSACHUSETTS FILLED PULP AND METHOD MAKING THE SAME No Drawing.

This invention relates to the manufacture of papermaking ingredients, and more particularly to a filled pulp and method of making the same.

The principal object of my invention is to provide a new method for shipping alkaline filler which is more convenient and economical than present methods.

An important object of my invention is to provide for the combined shipment of alkaline filler and pulp as one article, and the preparation of such article.

Another object of my invention is to provide means for reducing the number of paper- 16 making ingredients required to be handled in a paper mill.

A further object of'my invention is to provide accurate means for determining the amount of filler furnished to the beater.

Another object of my invention is to provide an alkaline filler in dry form, yet in such a condition that it is easily dispersible in water. 1

Another object of my invention is to provide a filled pulp for use as a raw material in' apermaking.

ther objects and uses of my invention will become apparent during the following description.

In the manufacture of ulp by alkaline digestion processes such or example as the soda,-sulphate, the modified Keebra process or the like, a soluble hydroxide such as sodium hy'droxide is one of the chemicals, if not the only one, employed. After digestion with the hydroxide has been completed the pulp is separated from the spent or black liquor, which is commonly evaporated, then subjected to incineration, yielding eventually sodium carbonate. This sodium carbonate is then commonly causticized, together with enough fresh sodium carbonate to make up the losses if desired, in order to produce sodium hydroxide.

The agent normall employed. to produce this sodium hydroxi e from the sodium carbonate (Na CO is lime (CaO and there is produced thereby, in the or nary causticlzing process, an alkaline filler, consisting 60 of relatively coarse grained calcium car- Application filed December 11, 1928. Serial No. 325,405.

bonate, i. e. lime sludge. This may if desired be utilized as a cheap filler in paper. Or the sodium carbonate may be causticized by a lime containing magnesia, as described finely divided material consisting substantially of calcium carbonate magnesium hydroxide, which has proven satisfactory as a paper filler, see Patent No. 1,598,104, granted August 31, 1926.

It will be apparent from the foregoing that in the causticizing process for the production of sodium hydroxide to be used in the alkaline process for cooking wood pulp, materials may be produced useful for fillin paper.

There are many cases in whic the pulp produced by the alkaline process is made into paper in a paper mill located on the same'or contiguous site. In such cases, the pulp is commonly pumped in aqueous suspension or slush to the point of use, or it may be deprived of a substantial portion of its water on a wet machine or the like, but under such conditions it is rarely dried, except possibly if it is desired to store it, owing to the expense involved.

Likewise at pul plants located as just described, the alkaline filler produced may be used in the paper there made, it being ordinarily pumped in aqueous suspension to its point of use,'or, less commonly, transported in a more or less dewatered condition in trucks or the like to its point of use. Only rareliy, as for purposes of storage, would it be drie before use, owing to the expense involved.

There are many cases, however, where the alkaline pulp and alkaline filler are both produced in excess of the paper requirements at the mill where they are manufactured and it thus becomes necessary to make shipment of the same. Of course such a condition would regularly obtain in the case of a pulp mill cooking pulp by an alkaline process situated at a distance from a pa er mill, in which case both the pulp and filler produced must be shipped.

The customary method of preparing pulp, 100

either bleached or unbleached, for shipment is to dewater it as much as feasible by mechanical means, as by means of a wet machine, press rolls, hydraulic presses or the like, and then ship it in wet form in laps or the like containing an appreciable percentage of water, or in many cases to supplement the mechanical dewatering treatment by a drying treatment, either on steam drum dryers in a continuous web from which itmay be delivered in substantially dry rolls, which may be shipped as such or after cutting into sheets which are usually then baled, or in other machines such as those producing flaked or shredded pulp which may be subsequently baled. As the pulp is arelatively expensive material the cost of dewatering and/or dry-' ing is not a disproportionately large part of its cost, and normally amply repays its cost in the diflerence in the freight caused by the reduction of water content.

On the other hand, alkaline fillers are rela tively inexpensive, and the cost of dewatering and/or-drying these is usually greater in proportion to their total cost than is the case with pulp, and this has became of the factors in discouraging the shipment of alkaline fillers from pulp mills. Moreover, if shipped withthe amount of moisture normally present when coming ofl the filter press or out of settling tanks, the alkaline filler is not rigid enough to maintain its shape, and it is thus unfeasible to ship it in bulk, and it must be shipped therefore in containers which are costly, or possibly even in tank'or hopper bottom cars, with excessive freight costs due to the contained-moisture. Moreover if it is desired to dry the filler, special machinery is required which is expensive and takes up much space. In addition, if the alkaline filler is dried practically bone dry there may be considerable difficulty in dispersing it properly inwater prior to use; moreover, even if an appreciable moisture content is maintained to prevent this difficulty, surface drying may occur which may cause trouble in the later dispersion in water. This water also, of course, serves to increase the cost of transportation.

I have, however, devised a method whereby all the difliculties inherent in shipping filler either dry or partly dewatered are elimi nated, and whereby filler and fibre, in excess of that amount of each desired to be utilized at the point of manufacture, may be inexpensively prepared for shipment, shipped economically, shipped in a form easily handled, and in a form which presents many advantages in the use of the materials.

Briefly my process consists, in its preferred embodiment, of mixing the fibre and filler in aqueous suspension, and passing the'mixture through the regular apparatus customarily employed for dewatering or dewatering and drying the pulp alone. If in the process of dewatering,some of the alkaline filler and/or pulp is lost in the waste waters, these materials can be recovered in any known manner, such as by cyclic reutilization in the process, by filtration, sedimentation or the like.

In the use of my process no special equipment for dewatering or dewatering and drying the filler is required. Also this processing may be more economically performed than where the two materials are processed separately. Moreover thecombined pulp and filler product is specifically heavier than the pulp alone and thus allows more material to be packed into freight cars than if the pulp alone were shipped. Furthermore by my process the filler is prepared in an easily handled form instead of as a paste or a powdery solid. At the point of use, moreover, there are several distinct advantages accruing to my inventlon, in addition to storage advantages,

namely the elimination of separate handling of one of the papermaking ingredients, the definite control of amount of filler going into the beater, but most important, in the case where. my pulp-filler product is shipped dry, is .the advantage that owing to its intimate mixture with the pulp, most of the filler readily disperses in water, and the remainder clings closely in finely divided form to the fibre, a condition greatly desired in papermaking practice, and making for great-. er retention of the filler in the paper.

It is thus seen that by my process I produce a combined pulp and filler product which'is delivered from the usual pulp dewatering or dewatering and drying machinery. My product may be shipped in any form in which pulp itself-is transported, such as in wet laps, in wet sheets, in rolls usually substantially dry, or in sheets, usually cut from these rolls, which are then usually baled, or in shredded or flaked form, usually baled. The product retains the pulp-like appearance and because of its fibrous nature, holds the filler in a form in which it would be impossible to handle and ship the filler alone. In soda pulp mills, for example, it is usually customary to ship the pulp in dry rolls and if my product is made at such a point, the alkaline filler is then contained with the pulp in these rolls.

I do not limit myself to any specific pro portion of filler to fibre in my pulp product as it will be readily seen that practically any proportions of the two materials may be used, the lower limit as to percentage of pulp being that which will be just enough fibre to run over the machinery used and hold the filler in the shape desired for shipment, whereas there is no definite minimumlimit on filler content other than the amount of filler required to bev shipped. However in practice inasmuch as in pulp mills producing alkaline filler the proportion of alkaline filler produced does not commonly run over 80 to However it is to be understood of course that under special conditions where proportionately more pulp than filler is used at the point of production, or where for other purposes it is desired to ship a product containm a larger roportion of filler to pulp than t at given a ove, these proportions may be varied within limits of the particular machine used to handle the product, and de nding upon the specific papers inwhic t e product is intended to be used.

It is at times customary in a pulp mill which has a paper mill run in connection therewith to utilize in the operation of the pulp mill a part or all of the excess white waters coming directly from the paper machines, or from white water recover systems. The use of such white waters ma e for the purpose of washing the pulp on lter presses or the like, or for providing water in cases where the water supply is otherwise inadequate, or for recovering what minor amounts of suspended material mayexist in the white water. Such suspended material consists chiefly of fibre in the case where unfilled paper is being made, and of both fibre and filler where filled paper is being made. It will therefore be apparent that a minorper- 'centage of filler may be incorporated into the pulp where such practice is employed. The percentage of filler so introduced into the pulp will obviously be small, usually at the most not overseveral per cent. Thus, whereas I do not set a minimum limit on the amount of filler incorporated in my .filled pulp, manifestl a minor percentage of filler such as would eincorporated into pulp by the utilization of machine white waters.

wouldbe 'much below that mount which it would be economically worth while to employ in my invention, and I'therefore exclude 5 from the scope of my invention pulps which contain a minor and commercially insi nificant percentage offiller incorporated t erein, such pulps for example as those in whichthe filler content is derived chiefly from white water originating from paper machines.

I also exclude from the scope of this invention formed articles made of pulp which may contain filler, such as dishes, papier mach objects, and the like, not originally intended as raw materials for paper making, but which, as fibrous waste material, may find their wa into a paper furnish along with other discarded or imperfect articles containing fibrous material.

As stated above the customary method of preparing pulp for shipment is merely to transport it in liquid form to the pulp dewatering or dewatering'and drying machine. It is not customary to give it any treatment in a machine, such as a heater, or in a refinaccomplished in the paper mill by treatment in a beater and/or Jordan.

It is well known of course that old papers which contain filler are used as a re lar constituent of paper in the pa erma 'n process, and that these consist 0 course su stantially of fibre and filler. However, thepoint which distinguishes my filled pulp product from such material is that the fibrous material in'the preferred embodiment'of my product has not received mechanical treatment, that is, heating or. refining, such as the fibrous constituent of the old paper has received. While it is true that'in the manufacture of some papers, for instance, as in certain cases in newspaper manufacture, the beater is sometimes dispensed with, in no paper product to my knowledge is a fibre furnish which has been mechanically untreated fed to a paper machine, and thus the fibre in all reused paper products has had sufficient mechanical treatment for preparing the fibre for-use in the particular kind of paper product into which it is made.

As my pulp in the preferred embodiment of my invention is untreated or un efined, this therefore completely difierentiaies my pulp product of filler and untreated fibre from old paper customarily reused in the papermaking process. Therefore my product inits preferred form may be said to consist substantially of'untreated or unrefined fibre and filler. The terms untreated and unrefined, refer to such treatment and refining as may be given pulp in the papermaking process.

Of course if for some special purposes it were desired to give the pulp a certain amount of mechanical treatment prior to its shipment, such pulp could still be utilized with my filler and would still be diflerentiat ed from filled paper now reused in the papermaking process, as such pulp would only be partially treated or refinedwhereas the fibre of the old paper has been fully treated and refined already prior to its reuse, and merely requires thorough disintegration and mixing in order that it shall be suitable for reuse.

Of course it is not necessary that my filler be combined with pulp made by an alkaline process. This is merely a matter of conven ience on account of the usual joint manufacture of the two products at the same place; If, however, pulp of another kind is manu factured at the same plant where an alkaline filler is manufactured, it can ofcourse be used with the alkaline filler to roduce my product, or in fact pulp cooked y the alkaline process in addition to pul made by any other process may becombine with alkaline filler and the combined product shipped. Of

' mean substantially water insoluble filler which when agitated with freshly boiled discourse even pulp produced at another point might be mixed with alkaline filler at the point of production of the alkaline filler, but of course if this pulp requires shipment prior to use, the expense involved would make such use practically prohibitive.

I ave described above my preferred method of mixing pulp intimately with alkaline filler. Of course such a completely intimate mixture is not essential to carry out my invention. The intimate mixture may possess a lesser degree of intimacy. For instance the alkaline filler may be applied as a layer on a pulp surface, for example as by being sucked on to a preformed layer of pulp such as might be formed on a cylinder machine or otherwise, and this layer, although penetrating to a certain extent the fibre layer, would necessarily of course exist in the greatest concentration onthe surface of the fibre.

. Another adaptation would be where the alkaline filler might exist as a layer or layers between two or more pulp layers such as might be produced on a cylinder machine, or where the pulp layer might be coated on both sides with tiller layers. These and other variations of course will become apparent to those skilled in the art. and all such methods of combining alkaline filler and fibre to make a fibrous filler product which can be handled substantially in the same manner as it could be were there no filler present with the pulp fall within the scope of my invention.

\Vhere I use the term alkaline pulp I mean a pulp which has been cooked with a cooking liquor containing a soluble hydroxide as a major or minor constituent. Such pulps are soda pulps, sulphate pulps, modified Keebra pulps, and the like.

\Vhere I use the. term alkaline filler, I

tilled water,.say for an hour, will impart a pH value to such water greater than 7.0. that is, which will been the alkaline side of the neutral point. Among the fillers included in this group may be mentioned calcium cabonate, of which lime mud from-the causticizing process is one form; calcium carbonate magnesium basic carbonate employed Patent No. 1,595,416, issued August 10, 1926; calcium carbonate magnesium hydroxide disclosed in my U. S.-Pateut No. 1,416,391, is-

sued May 9. 1922: and other substantially water insoluble normal or basic. carbonates of alkaline earth metals (which expression is herein intended to include magnesium), or compounds, double salts, or physically associated mixtures of these with one or more other acid soluble materials of a substantially water insoluble nature. I

When I use the word paper herein, I use it in the broad sense to include products of manufacture of all types and of all weights in the paper disclosed in my U. S.

and thicknesses, which contain as an essential constituent a considerable amount of prepared fibre and which are capable of being produced on a Fourdrinier, cylinder, or other forming, felting, shaping or molding machine.

While I have described in detail the preferred embodiment of my invention, it is to be understood that the details ofprocedure, the proportions of ingredients, and the arrangement of steps may be widely varied without departing from the spirit of my invention or the scope of the subjoined claims.

I claim:

1. The'method of preparing alkaline filler for shipment comprising combining in wet condition said alkaline filler with pulp.

2. The method of preparing alkaline filler for shipment comprising combining in wet condition said alkaline filler with pulp, and removing water from the combined materials.

3. The method of preparing alkaline filler for shipment comprising combining in wet condition said alkaline filler with pulp, and degatering and drying the combined mater1a s.

4. The method of preparing alkaline filler for shipment comprising mixing pulp and alkaline filler in wet condition, and running the resulting mixture on a wet machine.

5; The method of preparing alkaline filler for shipment comprising mixing pulp and alkaline filler in wet condition, and running the resulting mixture on a wet machine to form a combined pulp and filler web.

6. The method of preparing alkalinefiller for shipment comprising mixing pulp and alkaline filler in wet condition, running the resulting mixture on a wet machine to form a congbined pulp and filler web, and drying said we 1 7. The method of preparing alkaline filler for shipment comprising mixing pulp and alkaline filler in wet condition, running the resulting mixture on a wet machine to form a combined pulp and filler web, drying said web, and winding said web into rolls.

8. The method-of preparing alkaline filler for shipment comprising mixing pulp and alkaline filler in wetv condition, running the resulting mixture on a wet machine to form a combined pulp and filler web, drying said web, winding said web into rolls, and subsequently cutting said rolls into sheets.

9. The method of preparing alkaline filler for shipment comprising mixing pulp and alkaline filler in wet condition. running the resulting mixture on a wet machine to form a combined pulp and filler web, drying said web, winding said web into rolls, subsequently cutting said rolls into sheets, and then baling said sheets.

10. A composition of matter in condition for shipment comprising substantially unlliv refined pulp and alkaline filler in intimate association.

11. A composition of matter comprising an intimate association in layer formation of zllilbstantially unrefined pulp, and alkaline 12. A composition of matter in condition for shipment comprising substantially unrefined alkaline pulp and alkaline filler in intimate association. I

13. A composition of matter in condition for shipment comprising substantially unrefined soda pulp and alkaline filler in intimate association.

14. A composition of matter in condition for shipment comprising substantially unrefined pulp and alkaline filler comprising an alkaline earth metal compound in intimate association.

15. A composition of matter in condition for shipment comprising substantially unrefined pul and alkaline filler comprising calcium car onate' in intimate association;

16. A composition of matter in condition for shipment comprising substantially unrefined pulp and alkaline filler comprising calcium carbonate magnesium hydroxide in intimate association.

17. A composition of matter in condition for shipment comprisinglsubstantially unrefined pul and alkaline ler comprising calcium carbonate and magnesium compound in intimate association.

18. A composition of matter in condition for shipment comprising substantially unrefined soda pulp and alkaline filler comdprising .calcium'carbonate magnesium hy roxide in intimate association.

19. A raw material for use in the paper industry comprising a filled pulp in a form capable substantially of maintaining its shape containing pulp and alkaline filler in -intimate associatio '20. A raw material-for use in the paper industry comprising a filled pulp in a form capable substantially of maintaining its shape containing alkaline pulp and alkaline filler in intimate association.

21. A composition of matter in a form capable substantially of maintaining its shape comprising substantially unrefined pulp and alkaline filler.

22. A filled pulp in a form capable subthe fillerand pulp are subsequently combined for shipment.

25. A process of manufacturing pulp and filler wherein the metallic-radicle of the filler is derived from lime used in the preparation of liquor for pulp digestion, and the filler and pulp are subsequently combined for shipment.

26. The method of preparing filler for shipment, said filler containing a metallic radicle derived from lime used in the production of sodium hydroxide, comprising combining in wet condition said filler with pulp.

27. A composition of matter in condition for shipment comprising substantially unrefined pulp in intimate association withefiller, said filler containing a metallic radicle derived from lime used in the production of sodium hydroxide.

28. A raw material for use in the paper industry comprising a filled pulp in a form capable substantially of maintaining its shape containing pulp and filler in intimate association, said filler containing a metallic radicle derived from lime used in the production of sodium hydroxide.

In testimony whereof I aifix my signature.

' HAROLD ROBERT RAFTON.

stantially of maintaining its shape which is characterized by being readily dispersible in water, comprising pulp and alkaline filler.

23. The method of shipping alkaline filler comprisingcombining it prior to shipment with pulp into a form capable substantially of maintaining its shape, and thereafter shipping same.

24. A process of manufacturing pulp and filler whereby filler is produced in the preparation of liquor for pulp digestion, and