US1808071A - Method of producing paper filled with alkaline filler - Google Patents

Description

Patented dune 2, $.31

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We at TENT HAROLD R. RAITON, OF LAWRENCE, MASSACHUSETTS, ASSIGNOE. TO BAIFOLD PROCESS CORPORATION, A CORPORATION OF MASSACHUSETTS METHODOF PBIODUCING PAPER. FILLED WITH A '1 117 mum 1T0 Drawing. Application filed November 24, 1928, Serial No. 321,754. Renewed August 15, 1980.

This invention relatesto the manufacture of paper and more particularly to a method of producing paper filled with alkaline filler.

The principal object of my invention isto 5 provide a method for making either unsized or sized paper filler with alkaline filler" .wherein both alkaline filler and alum are added to a fibrous mix at such a point in the papermaking process that the time and intimacy of contact of the alkaline filler and alum in the mix are materiall limited.

An important object of my invention is to provide a method for the reduction, elimination, prevention, or alteration of foam in the manufacture of substantially unsized pa per filled with alkaline filler. A further object of my invention is to improve paper machine operation in such manu- 00 facture, particularly as regards the dandy roll.

A further object is to avoid the deterioration by alkaline filler of the effect of alum in a paper mix.

A further object is to avoid the deterioration of a precipitate of size and alum by alka- A further object is to provide a method of.

making paper filled with alkaline filler wherein alkaline filler and alum in conjunction with a soluble material such as size and/or other soluble material are added at such a point in the papermaking process that the time andintimacy of contact of the alkaline filler in the paper mix with the precipiv} tates formed from these materials and alum are materially limited.

Another object is to provide a process wherein alkaline filler is employed, in which the broke may be fed to the beater.

Another object is to provide a process in be insured, by which sized papers ma which the recovered stock from the white water may be re-utilized either in thebeater or in one of the stufi chests.

Another object is to provide a cyclic process in which alkaline filler is used at the wet end of the paper machine in conjunction with alum, in which the broke from the machine is re-utilized inthe heater and in which the constituents recovered from the white water are re-introduced at a point prior to that where the fibrous mix is diluted 'reparatory to delivery to the web-forming evice of the pager machine;

ther objects and advantages of my invention will become a parent during the course ofthe following escription.

In my copending applications Serial No. filed September 5, 1928, and Serial No. 321,753, filed November 24, 1928, I have disclosed and claimed methods whereby sized and substantially unsized paper filled with alkaline filler may be made by adding alkaline filler at the wet end of the paper machine. Moreover in my copending applications Serial Nos. 304,168, 304,170, 304,171, 304,172, 304,173, 304,174, 304,176 and 304,177, all filed September 5, 1928, and-in my copending applications Serial -Nos. 319,710i

and 319,720, both filed November 15, 1928,

have described and claimed various methods wherein alum is added at the wet end of the paper machine by which foaming may be p'evented on the tter operation 0 the paper machine may paper machine, by which made, by which material originally so uble' may be incorporated into paper, all in the case of paper filled with alkaline filler.

In the applications mentioned above I have disclosed that certain eifects produced-by the addition in the beater of alum, or of alum and size, or of alum and soluble material such as sodium silicate, are deteriorated even up to the point of destruction by the presence 0 alkaline filler.

As indicated, I have employed soluble material such as paper machine, or in other words atthe wet end of the pa .dition of alum at the wet the alkaline filler this method is the two general methods which serve either to restore these effects which have been deteriorated or destroyed, or to prevent these effects from being destroyed, namely, the adend of the paper machine to a paper mix which already contains alkaline filler or the addition of alkaline filler at the wet end of the paper machine to a papermix to which alum has already been added, and in which the efi'ect desired to, be produced already exists. I

. Cross references have been made in several of the applications to the possibility of the joint use of both of these methods under certain circumstances but claim has not been made thereto. In the present application claim is-made to the joint use of these two methods both for sized and substantially unsized paper, and further disclosure as to advantages which inhere in a combination of these two methods is made.

My process consists substantially in adding originally all the-fibrous constituents in the heater 'or similar machine, and then adding subsequently to these fibrous constituents (not including alkaline filler admixed with fibrous constituents) and alum, together with size, if desired, and/or sodium silicate, at a point in the process where there will be a minimum of time and intimacy of contact of the constituents ofthe mix, that is at or subsequent to the point at which the relatively concentrated mix is diluted preparatory to delivery to the web-forming device of the er machine. The chief a vantage of the employment of fact that broke containing. alkaline filler may thereby be used directly in the beater. Furthermore the material recovered from the white water which of course contains alkaline filler may thereby be delivered, directly into the beater or at any other point where the stock is stillin concentrated condition, such for instance as in any of the stufi'chests. This procedure permits theutilization of the equipment com monly used for white water recovery with the normally employed piping connections, instead of t e changed piping required by the processes set forth in my copending ap plications Serial Nos. 304 167 filed Septemer 5, 1928, and 321,753, filed November 24, 1928, Where the recovery system is of the filter or decker type, the sweetener stock may bewtaken exactly as is customary from one of the stufi chests and this stock together with the recovered material from-the white water may be returned thereto or elsewhere into the concentrated stock system as desired. Moreover the capacity of-thebeater for fibrous material is not.reduced by the presfiller. Furthermore the beating action is not retarded by the pres ence in the beater of material, i. e. filler, which mechanically covers the fibre and prevents full action thereon by the beater.

A further advantage is the tendency toward economy in alum as the alum and alkaline filler do not have an opportunity to react substantially within the brief time or any of the special sizing agents set forth in my various copending applications mentioned above; fourthly, for preserving in stock and in the paper made therefrom the substantially undeteriorated efi'ect imparted by a soluble material such as sodium silicate precipitated by a precipitant such as alum. I

In the preferred practice of my invention I add in the beater fibrous material which may conveniently include the fibrous material which comes under the definition of alkaline filler hereinafter set forth in this specification. Other material such as coloring matter may also be added at this point if desired.

\ After the usual subsequent treatment in the beater, the mix is preferably passed through the beater chest, Jordan, and machine chest in the customary manner. This exact procedure is not necessary and may be modified in accordance with the type of paper being made; moreover this placement of chests in respect to mechanical treating apparatus is subject to rearrangement as will be apparent to one skilled in the art. Where the machine is equipped with adecker or filter type of white water save-all, the sweetener stock may be drawn from one of the chests, and the stock, recovered from the white water combined with this sweetener stock, may be returned to the chestas is customary.

The relatively concentrated fibrous mix is now ready for dilution and is preferably at this point mixed with the alkaline filler, preferably in aqueous suspension. Of course white water, e. tray water, and other water is added as nee ed at this point. If, now, it is desired to use only alum as the additional material to be added to the mix, such as would be the case forexam le in the manufacture of substantially unsized paper where alum would be used for foam or improving machine operation or for any other use, the alum should now be added substantially free from foam manufacture of sized paper sized by any of the ordinary sizing materials, or byv the purpose ofpreventing the point of dilution,

to the dilute mix which contains the alkaline filler preferably thoroughly mixed therewith. If on the other hand it is desired to incorporate soluble material such as sodium silicate into the paper, or sizing material such as rosin size, or material such as an emulsion, e. g. a parafin emulsion (together with an agent which mutually with a precipitating agent later to be added serves to concentrate the disperse phase of said emulsion on the fibrous material) one or more of these materials may then be addedtothe dilutedmix containingthe alkaline filler, and when sufiicient time has been given for them to be thoroughly mixed, the precipitating agent such as alum may'then be added. Of course the alum may be added prior to these materials, and likewise of course the alkaline filler need not be added first, but the above is a suitable method for carrying out my invention. Moreover any two or more of the materials, preferably those which do not mutually'i'eact with one another, may be pre-mixedoriginally, such for example as the alkaline filler and rosin size solution, so as to necessitate a lesser number of materials to be mixed directly with the fibrous material at the wet end of the paper machine. Special mixing devices may be provided for incorporating the various materials with the fibrous mix, but usually the alkaline filler, preferably in aqueous suspension, is added at and the other materials may be satisfactorily added successively, as the ordinary turbulence'of the diluted mix,

in the rifiier for example, is suflicient to efiect proper mixing. The ordinary time existing in machine operation between the point of dilution of the stock and its delivery to the webforming device is usually amply suflicient to se arately:

eiiect complete mixing. Of course the size and/or other soluble material such as sodium silicate -may be previously added with the fibrous mix while the mix is in a relatively concentrated condition, but the important point is to add both the alkaline filler and the alum at the'wet end of'the paper machine. It is also possible of course to add the'previously precipitated sizing and/ or aluminum silicate at the wet end of the paper machine as set forth in my copending application Serial No. 304,17 5 filed September 5, 1928, and Serial No. 319,721, filed November 15, 1928, but I prefer to add the unprecipitated constituents he is now fed on to theweb-forming device of the paper machine and the white water flowing therefrom may be returned cyclicly to the process. Part of this maybe used as such in diluting the stock in the m1xing box of the paper machine. Part, if desired, may be treated by sedimentation, filtration, deckering, or' the like, recovering the matter in suspension therein for return to heater or chest, and returnin as much of the clarified water as itmay e feasible to Broke employ. for re-use on the'machine or in the rest of the papermaking operation.

An illustrative furnish suitable for the practice of my invention is as follows:

Materials added in the beater Pounds Materials to be added proportionately and 'eontinuowrly on dilution.

Pounds Alkaline filler (bone dry basis), e. g.

calcium carbonate magnesium hydroxide Alum Another illustrative furnish is:

Materials added in the beater Pounds Fibrous material (air dry basis), e. g. equal parts of sulphite pulp, soda pulp, and old paperstock 1550- Broke (air dry basis), such as from the operation of the same machine or other broke containing alkaline filler. 150

Materials added-proportionately and coatinuously on dilution Pounds Alkaline filler (bbne dry basis), e. g.

calcium carbonate a magnesium hy- I droxide 300 Size, e. g. rosin size 6 Alum p 4 Another illustrative furnish is:

--Materals added in the beater Pounds Fibrous material (air-dry basis),'e. g. equal parts of sulphite pulp, soda pulp, and old paper stock 1550 Broke (air dry basis), as from the operation of the same machine or other broke containing alkaline filler 150 Materials added proportionately and continh uo'usly on dilation Alkaline filler (bone dry basis), e. g.

calcium carbonate magnesium hy- Pounds droxide 300- Inorganic alkali metal salt, e. g. 60 7 B. sodium silicate 40 Precipitant,.e. g. alum 50 Another illustrative furnish is Materials added in the beater v r Pounds Fibrous material (air dry basis), e.' g.

equal parts of sulphite pulp and soda pulp 1550 (air basis), as from the opera ation of the same machine or other broke containing alkaline filler' however, under conditions Size, e. g. rosin size;

Materials added proportionately and con- Alum 85 It is to be understood that the above furnishes are illustrative'only and not limiting, as I have found that my invention may be practiced with a wide variety of ingredients in the furnish, with widely varying proportions of the several ingredients to one another, for making a wide variety of grades of paper.

As will be apparent from the previous detailed discussion, it is very desirable to be able to utilize in a paper mix both a water soluble acidic constituent, alum, and a substantially water insoluble alkaline constituent, alkaline filler. These two materials, obtaining in the ordinary method of paper manufacture react chemically upon one another so that the effect. of the alum is rapidly destroyed. The primary object of this invention is to so adjust conditions as to substantially prevent these two constituents from reacting chemically,-and thus to preserve the desired effect of the alum in the paper-making mix. This result is attained as indicated above by ad j usting conditions so that these two constituents are brought together in the paper mix under circumstances which tend to prevent their chemical reaction, that is, under conditions favoring the minimizing ofthe time and intimacy of contact of the constituents of the mix, or specifically, at the wet end of the paper machine. It is thus obvious that conditions are adjusted -to prevent rather than to obtain a chemical reaction between the alum and the alkaline filler.

A chemical reaction between acidic material and alkaline material which is to result in a' final state which is substantially in the vicinity of neutrality requires of course the employment of substantially chemically equivalent proportions of the two materials. Thus if it were desired to effect such a re action between alum and alkaline filler, sub stantially chemical equivalents of each would have to be employed. A stoichiometrical cal culation shows that if for example calcium carbonate were to bethe alkaline filler used, 1 part thereof would be chemically equivalent to 2.2 parts of commercial alum. If calcium carbonate magnesium hydroxide (of equimolecular proportions) were to be the alkaline filler used, 1 part thereof would be chemically equivalent to 2.9 parts of alum.

, In the present invention, however, no such chemically equivalent proportions of alkaline filler and alum are used, but rather the amount of alkaline filler used is far in excess of the chemical equivalent of the alum used. This is made clear by reference to the first illustrative example of furnishes given above,

in which the alkaline filler,in that case calcium carbonate magnesium hydroxide, has a ratio of filler to alum of 25 to 2.9. Thus it is apparent that in that case there is used 25 times the amount of alkaline filler which would be the chemical equivalent of the alum, that is, 25 times the amount of alkaline filler necessary to react completely with the alum were conditions provided favorable for the consummation of reaction between the two. In the other illustrative examples the ratio of fillerv to alum is somewhat lower and runs in the extreme case (fourth example) as low as 10.2 of alkaline filler to 2.9 of alum, that is, the alkaline filler is 10.2 times the chemical equivalent of the alum. This latter ratio,

however, cannot be considered so representative of the ratio of the filler to alum employed in my invention as the ratio in the first example, because in the fourth illustrative furnish referred to there is present considerable amount of soluble alkaline material (size) which immediately removes a large part of the alum from the solution as an alum-size precipitate. Thus the actual free alumpresent, that is, the alum in excess of that needed to precipitate soluble constituents and which is actually the alum available for possible reaction with the alkaline filler, is considerably less than the total alum origi nally employed. Therefore the proportion of alkaline filler to free alum is actually much higher than 10.2 times the chemical equivalent of the alum as calculated above, and much nearer the 25 times given in the first example.

It is apparent therefore that I use an amount of alkaline filler far in excess of the chemical equivalent of the alum employed. Thus even were conditions such that the alkaline filler were acted upon by the alum, as is substantially not the case, under such conditions the unacted upon residual alkaline filler would only be slightly less in amount than that originally added, and thus substantially the same amount as added, (less, of course, the losses through the machine wire into the white water), would find its way into the paper. While I have not limited my invention to the addition of any definite amount of alkaline filler in relation to the total furnish, the examples of illustrative furnishes indicate that the proportion of alkaline filler normally present constitutes a substantial percentage of the total furnish, and thus the paper produced by my process will contain a substantial percentage of alkaline filler and will be what is known in the art as paper filled with alkaline filler.

On the other hand if instead of using alkaline filler as is mypractice in an amount greatly in excess of the alum used, alkaline a ses or;

ered as a paper filled with alkaline filler..

In order to compute the amount of alkaline filler that would be chemically equivalent in amount to the alum, it is only necessary to know how much alum is ordinarily used. From the examples of illustrative furnishes above, it is apparent that whereas I have not limited my invention to the addition of any definite amount of alum in relation to the total'furnish, the proportion of alum used on the total furnish normallyi runs in the vicinity of several per cent. more or less. For example if I used 3% of free alum on the total furnish, which is somewhat more than the average amount used in the illustrative furnishes, the amount of alkaline fill; er chemically equivalent thereto would be,

- in thecase of calcium carbonate, about 1.4%,

and in the case of calcium carbonate magnesium hydroxide about 1.1% on the total furnish. The resulting paper would, of. course, contain smaller percentages of filler owing to losses of filler throu h the machine wireinto the white waters. guch amounts of filler, therefore, 91;; even amounts in some excess thereof, (such as would be present if the alkaline filler were used in amounts chemically equivalent to quantities of alum somewhat larger than the above assumed 3% would be wholly inadequate to impart any substantial degree of filling to the paper made with such furnish. Indeed, in such case analyfical procedures of fairly-exact degree of refinement would have to be employed to detect the presence of such minute quantity or the alkaline filler as might find its way into the paper to distinguish it with certainty for instance from the small amounts of inorganic constituents naturally occurring in the fibres, such as sulphite or soda fibers. On the other hand, the filler in paper ordinar- I ily known as filled paper, such as that to which my invention is directed, is present in so much larger amount that the normal is completely inorganic constituents of the fibre negli 'ble in roportion thereto, and ordinary 'ng of t e pa er by ignition gives a result indicatin the er content sufliclently accurately or pr tical paper mill purposes.

It is thus clearly evident that I add alkaline filler and -alum at the wet end of the paper machine to prevent chemical reaction between the two'and therefore my invention difierentiated from any paper ma rooedure wherein an alkaline filler and alum in substantially chemically equivalent roportions are .added to a papermakmg mix ibr chemically reacting purposes. Moreover it is to be noted that where the procedure of adding substantially chemiy the mix would have been alkalinized and the sizing would have been substantially deteriorated if not destroyed. The prior practice madeno distinction between soluble and insoluble alkali. When substantially insoluble alkali was used as a substitute for the soluble alkali it was subject .to the same limitations as to quantity employed, and according to all known prior art the addition of an amount of insoluble alkali, e. g. alkaline filler, substantially in excess ofthat chemically equivalent to the acid added would have resulted in alkalinizing the mix to such an extent as to' substantially deteriorate if not destroy the sizing, and thus have defeated the purpose for which it was added. It was not until the discovery herein disclosed, namely,that alkaline filler if added at the wet end of the paper machine would not substantially affeet the desirable acidiciqualities in-a paper 'mix, that it was realized that an amount of alkaline filler greatly in excess of the chemical equivalent of the acidic constituent could "be added at that point without thereby aladdition of both acid and alkali at the dilute stage was necessarily confined by the-then existing knowledge to the addition of substantially chemically equivalent proportions. It is also clear that my invention is directed to the manufacture of paper filled in substantial degree with alkaline filler,'and it is thus completely difierentiated from any papermaking procedure in which alkaline filler and alum are added in chemically equivalent proportions, as in the latter case a' commercially wholly inconsequential amount of alkaline filler, if indeed any quantity at all detectable by ordinary analytical (procedure, is. incorporated into thefpaper, an such paper cannot be considered in'the ordinary pape making interpretation of the words as paper filled with alkaline filler.

Instead of alum as a precipitant for the rosin size, I may useiother' salts of aluminum, or sodium bisulphate (NaHSOQ or the like; but from the standpoints of efliciency and cost I prefer alum. In the case of the use of alum as a precipitant for sodium silicate, I may also substitute in addition to the above, ammonium salts such as the chloride or the sulphate.

.tration.

Instead of rosin size, which may be referred to as sodium resinate, and which may therefore be termed an alkali metal salt, any other size is suitable which is used in conjunction with a size precipitant as alum. One example of such a size is a. soap, such as an. oleate. Another is: a wholly or partially saponified wax, such as beeswax. Or I may use special sizing aents e. g. those involving the use of para n emulsions as disclosed in several of my copending applications referred to abov Where I use the expression alkali metal, I mean to include the hypothetical alkali metal ammonium (NI-I By the term alkaline filler I mean substantially water insoluble filler which when agitated in contact with freshly boiled distilled water, say for an hour, will impart a pH value to such water greater than 7.0, that is, which will be on the alkaline side of the neutral point. Among fillers included in this grou may be mentioned calcium carbonate, of w ich lime mud from the causticizing process is one form; calcium carbonate magnesium basic carbonate employed in the paper disclosed in my U. S. Patent No. 1,595,416, issued August 10, 1926; calcium carbonate magnesium hydroxide disclosed in my U. S. Patent No. 1,415,391, issued 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.

By the term alkaline filler I also intend to include fibrous material and/or other material such as paper coating constituents or the like containing one or more compounds of the character referred to, such as old papers or similar papers, broke, or the like.

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 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 0r molding machine. 4 v 1 By the term wet end of the paper machine I intend to include those instrumentalities employed in paper manufacture by which and/or in which a relatively concentrated paper mix is diluted, and treated, conveyed or fed up to the point of web-formation, such as, the mixing box, regulating and proportioning devices, rifllers, troughs, screens, head boxes, inlets, and the like, including also instrumentalities used in the white water cycle.

While I have described in detail the preferred embodiment of my invention, it is to be understood that the details of procedure,

filled with alkaline filler comprising adding alkaline filler.'in an amount sufiicient to impart a substantial degree of filling to the resulting paper, and an aluminum salt tofibrous material under conditions favoring the minimizing of intimacy and time of contact, and thereafter making paper therefrom.

3. The method of manufacturing paper filled with alkaline filler'comprising adding alkaline filler in an amount suificient to impart a substantial degree of filling to the resulting paper, and an aluminum salt to fibrous material at the wet end of the paper machine, and thereafter making paper therefrom. 4. The method of manufacturing paper filled with alkaline filler comprising adding alkaline filler in an amount sufficient to impart a substantial degree of filling to the resulting paper, and alum to' fibrous material at the wet end of the paper machine, and thereafter making paper therefrom.

5. The method of manufacturing aper filled with alkaline filler comprising a ding alkaline filler, in an amount suflicient to impart a substantial degree of filling to the resulting paper, soluble material, and an aluminum salt to fibrous material at the wet end of the paper machine, and thereafter making paper therefrom.

6. The method of manufacturing paper filled with alkaline filler comprising adding its alkaline filler, in an amount sufiicient to impart a substantial degree of filling to the resulting paper, soluble material comprising alkali metal salt, and an aluminum salt to fibrous material at the wet end of the paper 530 sulting paper, soluble material comprising reason machine, and thereafter making paper therefrom.

7. The method of manufacturing aper filled with alkaline filler comprising adding alkaline filler, in an amount suficient to impart a substantial degree of filling to the resulting paper, soluble material comprising size, and an aluminum salt to fibrous material at the wet end of the paper machine, and

thereafter making paper therefrom.

8. The method of manufacturing paper filled with alkaline filler comprising adding alkaline filler, in an amount sufficient to impart a substantial degree of filling to the resulting paper, soluble material, and alum to fibrous material at the wet end of the paper machine, and thereafter making paper therefrom.

9. The method of manufacturing aper filledwith alkaline filler comprising adding alkaline filler, in an amount suflicient to impart a substantial degree of filling to the resulting paper, soluble material comprising rosin size, and an aluminum salt to fibrous material at the wet end of the paper machine, and thereafter makin paper therefrom.

10. The method 0 manufacturing paper filled with alkaline filler comprising adding alkaline filler, in an amount sufficient to impart a substantial de ree of filling to the rerosin size and an inorganic alkali metal salt with a pH, value greater than 7.0, which is precipitable by material which depresses its hydroxyl ion concentration, and an aluminum salt to fibrous material at'the wet end of the paper machine, and thereafter making paper therefrom. s

11. The method of manufacturing paper filled with alkaline filler comprising adding alkaline filler, in an amount sufficient to impart a substantial degree of filling to the resulting paper, soluble material comprising rosin size andsodium silicate, and an aluminum salt to fibrous material at the wet end of the paper machine, and thereafter making paper therefrom.

12. Themethod of manufacturing paper filled with alkaline filler comprising adding rosin size and sodium silicate,

alkaline filler, in an amount sufiicient to im- E part a substantial de ee of filling to the re-- material comprising and alum to fibrous material at the wet'end of the paper sulting paper, solub e machine, and thereafter making paper there-' from.

13. The method of manufacturing paperding alkaline filler consisting of alkaline earth metal-compound, in an amount sufficient to impart a substantial degree of filling to the resulting paper, and an aluminum salt to fibrous materialat the wet end of the paper Eachine, and thereafter making paper therefilled with alkaline filler comprising ad 14. The method of manufacturing paper filled with alkaline filler comprising adding alkaline filler consisting of calcium carbonate, in an amount suficient to impart a substantial degree of filling to the resulting paper, and an aluminum salt to fibrous material at the wet end of the paper machine, and there- .machine, and thereafter making paper therefrom.

16. The method of manufacturing paper filled with alkaline filler comprising adding alkaline filler consisting of calcium carbonate magnesium hydroxide, in an amount suflicient to impart asubstantial degree of filling to the resulting paper, and an aluminum salt to fibrous material at the wet end of the paper machine, and thereafter making paper there from. I

17. The method of manufacturing paper filled with alkaline filler comprising adding alkaline filler consisting of calcium carbonate magnesium hydroxide, in an amount suflicient to impart a substantial degree of filling to the resulting paper, soluble material, and an aluminum salt to fibrous material at the wet end of the paper machine, and thereafter making paper t erefrom.

18. The method of manufacturing paper filled with alkaline filler comprising adding alkaline filler consisting of calcium carbonate magnesium hydrom'de, in an amount sufficient to impart-a substantial degree of filling to-the resulting paper, soluble material comprising alkali metal salt, and an aluminum salt to fibrous material at the wet end ofthe paper machine, and thereafter making paper therefrom;

19. The method of manufacturing paper filled with alkaline filler comprising adding alkaline filler consisting of calcium carbonate magnesium hydroxide, in an amount sufficient to-impart a substantial degree of filling to the resultin paper, soluble-material comprising size, an an aluminum salt to fibrous material at the wet end of the paper machine, and thereafter making paper therefrom.

20. The method of manufacturing paper filled with alkaline filler comprising adding alkaline filler consisting of calcium carbonate magnesium hydrom'de, in an amount suflicient to impart a substantial degree of filling to the resulting paper, soluble material comprising rosin size, and an aluminum salt to fibrous material at the wet end of the paper machine, and thereafter making paper therefrom.

21. The method of alkaline filler consisting of calcium carbonate therefrom.

. filled with alkaline filler,

magnesium hydroxide, in an amount sufiicient toimpart a substantial degree of filling to the resulting paper, soluble material comprising size and sodium silicate, and an aluminum salt to fibrous material at the wet end of the paper machine, and thereafter making paper 22. The method of manufacturing paper filled with alkaline filler comprising adding alkaline filler consisting of calcium carbonate magnesium hydroxide, 1n an amount suflicient to impart a substantial degree of filling to the resulting paper, soluble material comprising size and sodium silicate, and alum to fibrous material at the wet end of the paper machine, and thereafter making paper therefrom.

23. The method of manufacturing paper comprising adding alkaline filler, in an amount suflicient to impart a substantial degree of filling to the resulting paper, and an aluminum salt at the wet end of the paper machine to fibrous material comprising sulphite and soda pulps, and thereafter making paper therefrom.

24. The method ofmanufacturing aper filled with alkaline filler, comprising a ding alkaline filler, in an amount sufficient to impart a substantial degree of filling to the resulting paper, and an aluminum salt at the wet end of the paper machine to fibrous material comprising sulphite and soda pulps and old paper stock, and thereafter making paper therefrom.

25. The method of manufacturing aper filled with alkaline filler comprising a (hug fibrous material in the beater, alkaline filler, in an amount suificient to impart a substantial degree of filling to the resulting paper, and alum at the wet end of the aper machine, and thereafter making paper t erefrom.

26. The cyclic procedure in a method of manufacturing paper filled with alkaline filler comprising the addition at the wet end of the paper machine of alkaline filler, in an amount sufiicient to impart a substantial de= gree of filling to the resulting paper, and alum, and the returning of the material recovered from the white water t0 the fibrous material while the same is in a relativelygconcentrated condition.

27. The cyclic prdcedure' in a method for the manufacture of paper filled with alkaline filler comprising the addition at the wet and of the paper machine of alkaline filler in an amount sufiicient to impart a substantial desaid manufacture tothe beater.

28. That step in a methodof manufacturing paper filled with alkaline filler which comprises adding alkaline filler, in an amount a er and aluminum sufiicient to impart a substantial de cc of fillin to the resulting paper, and aci ic materia to fibrous material at the .Wet end of the paper machine.

29. That step in a method of nianufactin: ing paper filled with alkaline filler which comprises adding alkaline filler, in an amount suificient to impart a substantial degree of filling to the resulting paper, and metallic salt to fibrous material at the wet end of the paper machine.

30. That step 'in a method of manufacturing paper filled with alkaline filler which comprises adding alkaline filler, in an amount sufficient to impart a substantial degree of filling to the resulting paper, and aluminum compound to fibrous material at the wet end of the paper machine.

31. That step in a method of manufacturing substantiallyunsized paper filled with alkaline'filler which comprises adding alkaline filler, in an amount suflicient to impart a substantial degree of filling to the resulting paper, and acidic material to fibrous material at the wet end of the paper machine.

32. That step in a method of manufacturing substantially unsizedpaper filled. with alkaline'filler which comprises adding alka-. line filler, in an amount suflicient to impart a substantial degree of filling to the resultin paper, and metallic salt to fibrous material at the wet end of the pa er machine.

33. That ste in a mat od of manufacturin substantia l unsized a1 aline filler w ich comprises adding alkaline fil er, in an amount suflicient to impart a substantial degree of filling to the resulting compound to fibrous material at the wet. end of the. paper machine.

In testimony whereof I afix my signature.

HAROLD ROBERT RAFTON.

paper filled with