US1929205A - Paper making - Google Patents

Description

Patented Oct. 1933 UNITED ST T S 1,959,205 rarna MAKING Clarence Earl Libby, Syracuse, N. Y., m... a National Aluminate Corporation, Chicago, 111., a corporation of Delaware The present invention relates to an improved process for the manufacture of paper, cardboard. pulp-board and the like, having special reference to the sizing and web-forming steps.

One 'of the major objects of the invention is to improve the efliciency of the sizing operation, as well as'to diminish the amounts of sizingreagents required to bring a given type of paper to a predetermined degree of size resistance.

A further object of the invention is to treat cellulosic fibers that are suspended in water in a beater with a water-soluble aluminate for the purpose of neutralizing the water to a point where ,the size, when subsequently added, will be more 15 efliciently dispersed so that, when it is later precipgliizted upon the fiber by the addition of the u l precipitants, such as aluminum sulphate, a much more thorough sizing of the fibers will result. A secondary, but. valuable, result is '20 obtained by the use of the aluminate" in that the resulting sized stock is considerably freer, so that the speed of web production can be considerably increased, w ile there will also beless loss of fiber in the wh e-water. 1

Other objects will become apparent as the invention is further described.

The invention therefore may be summed up asconsisting of the process of improving the sizing operation in paper manufacture by the ada justment of the acidity or hydrogen ion concentration of the vz'ater in the beater to about the point of neutrai ty (pH 7.0) by means of a soluble aluminate, followed by addition of the size and, later, by the usual aluminum sulphate. Ex-

act neutrality need not be attained, the useful range being between pH 5.0 to pH 8.0.

In this connection it should be understood that the action of the sodium aluminate is not one of mere neutralization, for, as will be shown in 40 detail hereinbelow, the effects obtained can not be interpreted merely upon the alkalinity of the sodium aluminate.

Paper is sized for the purpose of making it resistant to the penetration of water, ink, oil, or

' other fluids. Ordinarily, sizing is accomplished by introducing into the paper sheet a water resistant material such as rosin, glue, casein, or paramn wax. Rosin is the most common and eificient sizing material and is used in far greater 5 quantities for this purpose (than all other materials combined.

Rosin itself is not soluble in water but is brought into a soluble state by treatment with an alkali, the solution being accomplished either with or without the application of heat. The re- Drawing. Application span, 1932 Serial No. 603,223

suiting thick rosin soap", so called, may be added directly to the paper pulp beaters but is more commonly emulsified" or diluted with water to a concentration of 2% to 5% before it is added to the pulp stock. After the addition of the rosin emulsion, the size is usually set or fixed on the fibers by the addition of aluminum sulphate,

or paper makers alum, although in special cases the alum is added before the rosin size.

Notwithstanding the apparent simplicity of this operation, the practical results obtained are often quite variable and sometimes so unsatisfactory that the finished paper cannot be utilized for the intended purpose. It is possible to add the proper amount of size and alum in the correct manner and produce no increase in the size resistance of the paper over the unsized pulp, i. e., the

efficiency of the operation has been zero. While this result would seem unusual, it is not unusual, and in fact it is common for the size resistance of a given sheet manufactured in a single mill to vary in size resistance from run to run, from day to day, and even, in some cases, from hour to hour as much as several hundred percent.

I have found that the greatest cause of this fluctuation in size resistance is due to a varying acidity of the pulp suspension in the beater. The dispersion of the colloidal rosin size suspension is affected by this acid condition at the moment of addition to the beater, and the resulting size resistance of the paper manufactured from this pulp is a function of the dispersion of this size. Other factors being constant and within well defined limits, the greater the acidity of the pulp at the time of addition of the size, the less will be the size resistance of the manufactured paper. The variation in acidity of the pulp beaters is due to a number of factors, chief among which may be mentioned residual acid from the liquors in which the wood was cooked, acid from the bleaching operation, free acid from the alum and mineral filler which has accumulated in the white water, this water ordinarily being reused for dilution in the heaters, and acid resulting from the true hydrolysis of the alumi- 1-11 num sulphate.

The process which I have developed for the use of sodium aluminate in connection with the sizing operation depends in part on the power of the aluminate to-neutralize the pulp stock acidity its; and thereby create more favorable conditions for the dispersion of the rosin size emulsion.

In practice the pulp'suspension in the beater will have an acidity, expressed in terms of pH units, ranging from pH 3.5 to pH 8.5, depending llo upon the combination of factors enumerated heretofore and upon whether ,the pulp stock was prepared by an acid or an alkaline process. If the pulp was prepared by an acid process, or has been subjected to a bleaching treatment, or is suspended in the white water which drains away from the paper machine wires, it will have, ordinarily, an acidity not greater than pH 6.0 and probably not greater than pH 5.0. It is my process to adjust this acidity to approximate neutrality (pH 71)) by the addition of sodium aluminate, although in special cases the adjusted acidity varies from pH 5.0 to pH 8.0. The rosin size emulsion is then added and after thorough id agitation the mixture of rosin and-aluminate is precipitated throughout the pulp stock by the addition of suificient aluminum sulphate or other acid salt to adjust the acidity back to pH 4.0 or whatever figure has been determined to givefiii maximum sizing results.

The' use of sodium aluminate for this purpose is originai with me and gives results which cannot obtained with any other alkaline salt, theselresuits being due in part to the neutralizing 2d" powers)? the aluminate and in part to the colloidal fioc resulting from the interaction of the aluminate and the residual acid or aluminumsulphate dissolved in the water of the pulp suspension. This iloc being of itself a colloid serves to disperse the rosin size emulsion and greatly assists in the even distribution and uniform sizing ofthe'i entire paper she'etj f It is also evident that the presence of the aluminate causes a more complete precipitation of the rosin size, which brings abouta greater retention of rosin size in the sheet and results in less loss of size and alum in the machine white waters. This enables amill to greatly reduce the amount of rosin size addition to obtain a given degree of 40 sizing or size resistance in their paper and results in significant economies in the manufacturing process. If a mill is unable to manufacture a satisfactorily sized paper without aluminate, M the addition of this chemical will increase the 46 degree of sizing'in their product to a satisfactory value and thereby enable the milkto manufacture more salable merchandise.

In addition to the aforementioned benefits: the flocculating power of thealuminate added to. the E beater causes an agglomeration of the fine fibers in the pulp suspension, ,these fine fibers being trapped by the aluminatefioc and the whole mass enmeshed in the fiber structure of the paper I sheet in a manner which prevents these fine fibers 53" from passing through the fiber'mat of the wet paper sheet on the machine wire d subsequentlythroughthe machine wire 1 1f, resulting. in amarked decrease in the loss of fine fibers in the white water effluent-going to the sewers. 66 "Furthermore, the addition of sodlum aluminote to any paper pulp stock gives in some cases a soft flexible paper sheet similar to'a wood fiber .prepared'by the soda chemical pulping process A p and highly desirable for the manufacture of 66 bo'okpapers. By closely regulating the initial and final conditions of acidity, together with the time or treatmentin the boaters, exactly. the opposite effect may be produced, at will, and a F stiff strong paper sheet similar in characteristics .'0-- to a rag paper-sheet, may be manufactured from or oth'er fibers of inferior initialstreng'th and less economic value than'the-rag'fibers which 'Th'eaddltidn of aluminate' to .the pulp stock in thebeaters, or at any other point in the'line be the case.

(b) It permits the fibers to form or felt. more quickly on the paper machine wire and results in a more dense, uniform, and finely knit sheet known to the paper makers as a sheet with closed" formation.

(0) It enables the felts, suction boxes, and

presses of the paper machine to remove with less difiiculty the suspension water associated with the fibers and permits the paper machine to be operated at decidedly greater speeds.

(d) It enables the paper machine dryers to evaporate the residual water in the wet sheet leaving the presses with a smaller amount of steam, resulting in decreased drying costs and also permitting greater operating speeds, as the speed of the operation of a paper machine is often determined by its drying capacity.

(e) It largely negatives the tendency of hydrated pulp stock to shrink as it drys on the-rotating steam-heated drying drums of the paper machine and permits a machine to manufacture a sheet of greater width thanwould be possible without the use of sodium aluminate. I

. The results of tests made on an operating scale, using sodium aluminate in the heaters, with the object of increasing the efiiciency of the sizing operation, will now be described. I

These tests were made during a regular run of 16 point board, and, as a previous test had indicated that a substantial increase in the size test results from the addition of aluminate, an immediate cut of 25% in both the size and alum furnish was made simultaneously with the addition of aluminate. The size and alum furnish per beater during this test was as follows:

Alumisim nate at 46 lbs.

Ply Alum 50 lbs. 55 lbs.

4 lbs.

a; liner p 4 lbs.

Bottom liner out of 25% in both size and alum f 30 sec.

2. Size test on board manufact with a cut of 25% in th size and alum f h but with 41%. solid sodium aluminate l8 min. 18 sec. a

'. 3. Size test on board manufac ured with a s h, but with 4 lbs. ofrliquid sodium aluminate, (based on A120: content) in each liner beater-7 min. 54 sec.

An inspection of the foregoing tests indicates that a marked increase in sizing accompanies the ;45

use of solid sodium aluminate but that the liqui aluminate is not quite so effective, although the present standard test was practically maintained a with this product even after a 25% cut in size and alum. v C

in each liner beater I v per, three runs were made, one using ordinaryfresh lake water having an initial hydrogen-ion concentration of pH 6.4,,and when treated with the alum used for the precipitation, of pH 4.2. The size test in this case was 106 seconds. A second run was then made with the use of the white-water from the first run in the heaters, so that the water in the beater had an initial hydrogen-ion .concentration of pH 4.2 both before and after addition of the necessary paper-markers alum to effect the precipitation. The size test in this case was only 80.1 seconds. a

A third run was then made, employing the white-water from run No. 2, which had an initial hydrogen-ion concentration ofpH 4.2. Sufficient sodium aluminate was then added to bring the hydrogenion concentration of the water in the beater to the neutral point, i. e., pH 7.0. Thereupon the regular amount of size was added and the size precipitated by means of alum, in 'ex-' actly the way it had been done with the two preceding runs. The size test on the resulting paper was 277.4 seconds, or an increase over run No. 2 of 246%. It is thus plainly'evident that the addition of the aluminate very greatly increased the size resistance of the paper.

In order to obtain still more convincing proof of the remarkable effect obtained when practicing the present invention, a number of further test runs were made. These were as follows:

Run No. 4.-A run made for the purpose of preparing white water and employing aiurnish' of fresh water, rosin size, sodium aluminate and alum. Run No. 5.--A run made for the purpose of preparing white water and employing a furnish of white water from Run No. 4, rosin size, sodium aluminate and alum.

Run No.1 6.A run made for the purpose ofdetermining the specific effect of sodium aluminate on the efllciency of the rosin'sizin'g operation and employing a furnish of white water from Run No. 5, rosin size, sodium aluminate and alum.

In order to prove that the effect obtained could not be ascribed merely to the neutralization of the white-water used in the beater, three further test runs were made, using sodium carbonate as the neutralizing medium. These were as follows:

Run No. 7.-A run made for the purpose of preparing white water and employing a furnish of fresh water, rosin size, sodium carbonate and alum.

Run No. 8.-A run made for the purpose of preparing whitewater and employing a furnish of white water from run No. 7, rosin size, sodium carbonate and alum. v

Ru'n No. 9.A run made for the purpose of determining the specific effect 'of carboriate on the efficiency of the rosin sizing operation and employing a furnish -of white water from Run No. 8, rosin size, sodium carbonate and alum. I r

The details of these runs are as follows:

v I I Run No.4 v

Pulp-100% Dexter bleached mitscherlich sulphite pulp. v

Pulp furnish-10 lbs. air dry at consistency. Beating time-Two hours. fifteen minutes.

. Beater roll setting-3s on Bristol recorder.-

' 'ity of the pulp inthe beater to a pH of 4.2.

Alirminhte-Dissolved C. P. sodium alumina {e added after fifteen minutes of beating sufllcient quantity to increase the pH of the pulp suspension in the beater to a pH of 7.0 rosin size then added to the beater. Aluminate furnish-The equivalent of 4.4 lbs. of dry C. P. sodium aluminate per ton of air dry pulp. I Alum-Dissolved C. P. aluminum sulphate add-L ed after one hour fifty-five minutes of beating insufficient quantity to adjust the acidity of the pulp in the beater to a pH of 4.2. Alum furnishThe equivalent of 88.2 lbs. of C. P. aluminum sulphate per ton of air dry pulp. Green's freeness testNone. Test sheetsP-None.

Valley size test-None.

Run N0. 5

, Pulp- 100% Dexter bleached mitscherlich sulp i em n Pulp furnishlbs. air dry at 5% consistency. Beating time-Two hours, fifteen minutes. Beater roll setting-38 on Bristol recorder. Water-' White water from RunNo. 4, having aninitial pH of 4.2. Rosin size-Paper Makers'Chemical Corp.,

solids, 18% free rosin. Rosin size furnish-5% of 60% size, or 3% rosin on air dry weight of pulp. Aluminate-Dissolved C. P. sodium aluminate added after fifteen minutes of beating -and in sufllc'ient quantitylto increase the pH of the pulp suspension in the beater from pH 4.2 to a pH of- 7.0. Rosin size then added to the beater. I

Aluminate furnishThe equivalent of 18.7 lbs. of dry C. P. sodium aluminate per ton of air dry pulp.

Alum-Dissolved C. P. aluminum sulphate added after one hour fifty minutes of beating and in sufficient quantity to adjust the acid- Alum fumish--The equivalent of 88.2 lbs. of

C. P. aluminum sulphate per ton of air dry Green's freeness test-None;

Test sheets-None.

- Valley size test-None.

Run No. 6

Pulp-100% Dexter bleached mitscherlich sulphite pulp. Pulp furnish-l0 lbs. air at 5% consistency. Beating time-Two hours, 'fifteen minutes. Beater roll setting-38 on Bristol recorder.

waterwhite water from Run No. 5, having .an initial pH of 4.2. Rosin size-Paper Makers Chemical Corp.,

60% solids, 18% free rosin. Rosin size fumish5% of 60% size, or 3% main on the air dry weight of pulp.

added after fifteen minutes of beating in sufflcient quantitfto increase the pH of the pulp suspension in the beater to a'pH of 7.0. 'Rosinsizethenadd tothebeater.

1.4-? Aluminate-Dissolved C." P. sodium .aluminate Aluminate furnish-The equivalent or 18.7 lbs. of C. P. sodium aluminate per ton of air dry pulp.

Alum-Dissolved C. P. aluminum sulphate added after one hour fifty-five minutes of beating in sufllcient quantity to adjust the acidity of the pulp in the heater to a pH 01. 4.2.

Alum furnish-The equivalent of 88.2 lbs. 0! C. P. aluminum sulphate per ton of air dry pulp.

Greens freeness test-None.

Test sheetsFormed on Bureau of Standards sheet machine and air dried at 70 F.

Test sheet weights-29.1 grams for 4 sheets Valley size test data obtained at 70 F. and 65% relative humidity.

. Seconds sample 1 180 Sample 2 182 Sample 3 191 Sample 4 148 Sample 5 190 Sample 6 162 Sample '7 196 Sample 8 205 Sample 9 145 Sample 10 165 Average 176.4

Run N0. 7

Pulp-100% Dexter bleached mitcherlich sulphite pulp.

Pulp furnish-10 lbs. air dry at 5% consistency.

Beatingtime-Two hours, fifteen minutes.

Beater roll setting-38 on Bristol recorder.

Water-Fresh water having a pH of 6.4.

Rosin size-Paper Makers Chemical Corp.,

60% solids, 18% free rosin.

Rosin size furnish-5% of 60% size or 3% rosin on the air dry weight of pulp.

Aluminate-Nona Soda ash-Dissolved C. P. sodium carbonate added after fifteen minutes of beating and in suiiicientquantity to increase the 'pH of the pulp suspension in the beater from 6.4 to a pH of 7.0. Rosin size then added to the beater.

Soda ash fumish-The equivalent of 2.2 lbs. oi. CJP." sodium carbonate per ton of airy dry pu1p Alum-Dissolved C. P. aluminum sulphate added after one hour fifty-five minutes of beating and in suflicient quantity to adjust the acidity of the pulp in the beater to a pH of 4.2. Alum i'urnish--The equivalent of 88.2 lbs.'o1

pulp. Green's freeness test-None.

meaeoe Soda ash-Dissolved 3?. sodium carbonate added after fifteen minutes of beating and in suficient quantity to increase the pH of the pulp suspension in the beater from 4.2 to a pH of 7.0. Rosin size then added to the beater.

Soda ash furnish-The equivalent of 8.9 lbs.

I Green's freeness test-None.

Test sheetsNone. Valley size testNone.

Run No. 9

Pulp% Dexter bleached mitscherlich suiphite pulp.

Pulp furnish-10 lbs. air dry at 5% consistency.

Beating timeTwo hours, fifteen minutes.

Beater roll setting-38 on Bristol recorder.

Water-White water from Run No. 8, having an initial pH of 4.2.

Rosin size-Paper Makers Chemical Corp.,

60% solids, 13% free rosin.

Rosin size furnish-5% of 60% size, or 3% rosin on the air dry weight of pulp.

AIuminate-None.

Soda ash-Dissolved C. P. sodium carbonate added after fifteen minutes of beating and in sufiicient quantity to increase the pH of the pulp suspension in the beater from 4.2 to a pH of 7.0. Rosin size then added to the heater.

Soda ash furnishThe equivalent of 8.9 lbs. of -C. P. sodium carbonate per ton of air dry "pulp.

Alum-Dissolved C. P. aluminum sulphate added after one hour fifty-five minutes of beating and in sufficient quantity toadjust the acidity of the pulp in the beater to a pH of 4.2.

- Alum fumish-The equivalent of 88.2 lbs of C. P. aluminum sulphate per ton of air dry pulp.

. Green's ireeness test-None.

Test sheets-Formed on Bureau of Standards sheet machine and air dried at 70 F.

Test sheet weights-30.5 grams for 4 sheets Valley size test data obtained at 70 F. and 65% relative humidity.

Test sheetsNone."' Valley size testNone.

Run N0. 8

Rosin size furnish-5% of 60% size, or 3% rosin on the air dry weight of pulp. illuminate-None;

- Seconds Sample 1 125 Sample 2 135 Sample 3 120 Sample 4 107 Sample 5 118 Sample 6 122 Sample 7 115 Sample 8 134 Sample 9 i 110 Sample 10 Averag I 11 1 The procedures followed in making the runs Just described were identical with those employed inmalring runs Nos. 1-3. However, it was decided to make an accurate check on the quantity of aluminate, soda ash, and alum used as well as on the pH obtained, and the data obtained from these measurements are tabulated and discussed in the description to follow.

Owing to the considerable length of time required to complete these six runs, it was decided to omit the freeness test, as this test is quite time consuming and as very little variation in freeness could be expected when such close control was maintained over the beater 'roll setting and the time allowed for hydration.

It will be quite obvious to those skilled inthis art that the precise sequence of the addition of the materials need not be followed. For example, it would be an equivalent to add the aluminate to the water before mixing the fibers therewith; or to add the aluminate to the water, followed by addition 01' the size, and then to introduce the fibers. A third alternative is to add the fiber and aluminate and size simultaneously. In any event, the complete or partial neutralization of the water by the aluminate will aid in the proper dispersion of the size and in the beneficent results obtained by the use of the present invention.

A summary of all '01 the test results obtained is herewith tabulated, so as to bring out most (a) Thatthe neutralization of beater acidity with sodium aluminate prior to the addition of rosin size has a marked beneficial effect on sizing efllciency.

(b) That the beneficial efiect of sodium aluminate is partially if not wholly due to a more complete precipitation and retention of the rosin size in the paper sheet and a resulting cleaner white water.

(0) That the neutralization of beater acidity with sodium carbonate prior to the addition of rosin size has an effect somewhat similar .to that of sodium aluminate, but that the efiiciency of sodium carbonate as a neutralizing agent is apparently only one-third that of sodium aluminate.

It will thus be seen that the size resistance of paper can be increased from 120 to 277.4% by the use of sodium aluminate for neutralizing the white water when the same is used in making up the furnish for the beaters. When, on the contrary, sodium carbonate is used for a somewhat similar purpose, namely, to bring the white water to the neutral point before adding the size, and then precipitating the size by means of the usual papermakers alum (aluminate sulphate),

clearly the advantages of the present invention: the increase in size-resistance is only 49%. It

Efi'ect of the use of sodium aluminate and of sodium carbonate on paper sizing Beater water furnish Beater water pH I lg i n Neutralizing aggnt n s Size precip. in lbs. ggf increase Nature Source Init. Trted. run 2 3 Aluminate q. s 4. 2 7.0 277. 4 248% 4 Aluminate 4.4 6. 4 7. 0 Not run 5 Aluminate 18.7 4. 2 7.0 Not run 6 Alumiuate l8 7 4. 2 7.0 176. 4 120% 7 Soda ash 2.2. 6.4 7. 0 Not run 8 Soda ash 8.9. 4. 2 7. 0' Not run 9 Soda ash 8.9 4. 2 7. 0 119. 1 49% The foregoing test data explains the reason why the test values obtained for Run No. 3 in the first series of runs were abnormally high due to the fact that the white water for this run had not had previous treatment with aluminate. As will be noted, the test values for Run No. 6, which is identical with Run N0. 3 except that the white water for Run No. 6 had been treated twice previously with sodium aluminate, shows an increase in sizing value of 120% over Run No. 2,

suspended in unneutralized white water. This .test value of 120% corresponds with the test value of 246% obtained for Run No. 3, the run in which the white water had not been treated previously with aluminate. These comparative results furnish positive evidence that the function of the aluminate in increasing sizing efficiency is due to its ability to bring about a more complete precipitation and retention of the rosin size in the paper sheet, thereby clearing the white water of dissolved size and alum, and making possible a decidedreduction in size furnish to obtain a given size test value.

The effect of soda ash in increasing sizing efficiency is shown by the size test value obtained from Run No. 9. These test values indicate a degree of sizing 49% greater than the values from Run No. 2. These figures indicate further that sodium aluminate has approximately three times the beneficial effect of soda ash in increasing sizing efiiciency.

The conclusions to be deduced from the foregoing tests are:

will thus be quite apparent that a considerable step has been made in advancing this particular part of the art of paper making.

Reserving unto himself the benefits of the use of such equivalents as will occur to the experienced chemist and papermaker, what applicant has invented and claims is as follows:

1. The process of sizing cellulosic fibers tor the production of webs therefrom, which comprises treating the fibers in suspension with size and a water-soluble alkaline aluminate, and thereupon precipitating the size upon the fibers by means of an acid-reacting soluble reagent.

2. The process of sizing cellulosic fibers for the production of webs therefrom, which comprises treating the fibers in aqueous suspension with sodium aluminate and a size, and thereupon precipitating said size upon the fibers by the addition of an alum.

3. The process of sizing cellulosic fibers for the production of webs therefrom, which comprises treating the fibers in aqueous suspension with sodium aluminate and a size, and thereupon precipitatintg said size upon the fibers by the addition of aluminum sulphate.

4. The process of sizing cellulosic fibers which comprises treating the same first with a mixture of a rosin sizeand sodium aluminate, and thereupon precipitating both the sodium aluminate and the size by the addition of aluminum sulphate.

5. The process of sizing cellulosic fibers which comprises treating the same with a solution or a rosin size and sodium aluminate, and then acldi salt.

6. The process of increasing the size-resistance or paper which consists in suspending cellulosic fibers in water that has been neutralized by the addition of sodium aluminate, adding a rosin size to the suspension, and thereupon acidifying the suspension by the addition thereto of an acidreacting salt.

'1. The process of increasing the size resistance or paper, whic' consists in suspending cellulosic fibers and size in waterthat has been neutralized with sodium aluminate, and thereupon acidifying the resultant suspension by the addition of aluminum sulphate.

8. In the process of manufacturing paper from cellulosic fibers which are suspended in the whitee water from a previous run of paper-manufacture, the step of neutralizing said white-water by the addition thereto of suflicient sodium aluminate to bring the suspension to substantially the neutral point, adding size to the suspension, and precipitating said size upon the fibers.

9. The process of neutralizing white-water which comprises adding suflicient sodium aluminate thereto to bring it substantially to the neutral point.-

10. In the manufacture of cellulosic webs the tying the solution by means or an acid-reacting improvement which comprises suspending fibers in white-water, neutralizing the suspension with sodium aluminate, adding rosin size to the suspension, adding aluminum sulphate to the suspension, and thereupon sheeting the fibers. into a coherent web.

11. In the manufacture of webs from fibers, the improvement which consists in suspending fibers in an aqueous medium that has a hydrogen-ion concentration above the neutral point, bringing said medium to substantial neutrality by the addition of sodium aluminate, adding a precipitable size to the resulting suspension, and then precipitating said size upon the fibers by means of an acid-reacting salt such as aluminum sulphate.

12. The process of enhancing the efiicacy o! rosin sizing of fibers, which comprises neutralizing the water in which the fibers are dispersed by means of sodium aluminate, adding dissolved rosin size, and thereupon adding aluminum sulphate to form an insoluble precipitate of size and aluminum compounds upon the fibers.

13. The process of manufacturing sized paper which comprises preparing a mixture of fibers, a soluble aluminate and a sizing-agent, and treating this mixture with an acid-reacting size-precipitating agent.

CLARENCE, EARL LIBBY;