US2041294A - Method of making paper - Google Patents

Description

May 19, 1936. F. J. LANG I 2,041,294,

METHOD OF MAKING PAPER lNvENToR FAM/WC J. AA/6 ATTORNEY May 19, 1936. F. J. LANG METHOD OF MAKING PAPER Filed May 8, 1934 2 Sheets-Sheet 2 4 @QOGQQQQOQ 33 v @N N NM MM m ATTORNEY Patented May 19, 1936 FFICE il of Para Frank` ll. Lang, Niagara Falls, N. Y., assigner to International Paper ompany,

New Work,

u N. Y., a corporation oi New York Application May i934, S No. 124,536

My invention relates to the manufacture of paper and more particularly to a method of, and

apparatus for, producing paper having a filler.

such as calcium carbonate incorporated therein.

The principal object of my invention is to pro: vide a method whereby the amount of ller retained in the libres ofthe web is greatlyincreased, while a much smaller amount of alum than heretofore used is sumcient to bring about the objects of the invention. Another object of my invention is to provideI a method for the recovery of ller and color held in suspension in the white v water leaving. the machine and whereby to increase 'the efclency ilel';

A futher object of my invention is to increase the color qualities of lled paper While obtaining the desirable objects of saving materials, increasing the/retention of ller, and improving other characteristics of filled paper.

A further object of my invention is4 to bring about the above desirable objects in a 'closed system wherein the materials carried away by the of the usual suction pulp white water are reincorporated into the mix in order that a. greater Vamount of the materials may be incorporated into iinished paper.

The invention may best be understood in oon-4 nection with the sketches wherein;

Fig. l is a schematic representation Vof a system taking white water from the paper machine and redistributing it back to various points, and showing one point of application of alum;

Fig. 2 is a similar schematic representation of a system having the same general characteristics, wherein the alum is added at a. diierent pint;

Fig. 3 is a atie showing of the end o1 a Fourdrinier machine opposite the head box, and illustrating the collecti n of white water from the wire. v

In the of lilled papers it is common practice to add a carbonate, such as calcium carbonate, or other carbonates of alkaline earth metals, to the mix in such proportions as to increase'the opacity and brightness of the resulting paper. The amount of such carbonate re tained in the felted libres determines to a large extent the printing qualities of the paper, and thoroughness of incorporation tends to a large extent to prevent they formation of two-sided papers. Two-sided papers are usually the result of poor retention whereby the felt side o! the paper has more carbonate liner-,than the wire side.

following diagrtic (ei. ca -2i) Myprocess eliminates twosidedness to a great extent, as will appear. In'Fig. 3 the Fourdrinier wire l0 is shown passing over the usual couch roll lll, which in its preferred form is a ioraminous roll having light 5 suction applied thereto. ,In advance of the couch roll are the usual suction boxes l2, and in advance of the suction boxes are the usual table rolls i3. The felted libres are substantially formed into a web as they pass the table rolls, and the suction boxes and couch roll remove as much water as possible before the web passes on to the press rolls, the dryers and the calendar stacks. 'I'he table rolls support the wire, and beneath these table rolls is the wire pit M wherein most of the white water is collected. In adl Vance of the table rolls-,are the usual head box, slice, apron, etc., and practically the entire amount of water is passed through the wire somewhere between the head box and the suction boxes. This water falls into the'wire pit llt, from whichsome orall of the white water overiiows into the usual overflow box l5. llt is while the water is rapidly draining through the wire near the wet end of the machine that the greater percentage of lost hller is removed from the mix and passes into the wire pit. The suction boxes and couch roll remove more of the ller, and the white water from these is collected in the couch pit lt which has an outlet il lntothe overiiow box l5. It canbe' seen that whatever goes to make up the white water in the way of fibres,

t filler, or other matter, is collected in the overflow box l5 and passes into the white water t showninFlgsland 2. l

In Fig. 1 the overflow box l5 is utilized to add alum to the white water. This alum may -be incorporated by injecting an alum solution or by placing an ingot of alum on the oor of the overflow box. The action of alum on carbonates 40, in producing aluminum hydroxide and the effect thereof on the hbres and web formation is well known.

From lthe white water tank the white water is pumped into the i'iow box of a white water lter 45 wherein the chemicals soluble in water and the water are separated from the reclaimed stock. The coagulator, aluminum hydroxide, assists in flocculating the loose, minute bres so. that the lter may operate at its maximum eliiciency to remove the fibres. A screw conveyor may be utilized to start the reclaimed stock on its way to the illter chest.

The clear liquid passes into the clarliied white water sump andis pumped, either into a storage tank for future use, or to various points in the paper process. 'I'he claried water may be utilized as slush water for the washed soda pulp, as dilution water for -a dropping bleacher, as dilution water for the bleacher dump chest, as dilution water on the flat screens, or wherever white water may be used.

Regardless of what point the. clarified white water is returned into the system it will be` at a point prior to the beaters and Jordans, and from there on it will be for a considerable time and to a much greater degree than heretofore ,thought possible incorporated into the mix. The mix may thus consist of fibres and the diluting liquids, which in accordance with my invention will include reclaimed carbonate, alum and all of the products resulting from the chemical reaction of carbonates andA` alum. In the Jordans and in the beaters, these chemicals will be thoroughly mixed or incorporated into close contact with individual fibres.

The white water which is drawn through the wire contains only a relatively small percentage of solids. This will be appreciated when it is realized that the pulp stream emerging from the slice has only one to one and a half parts solids in one hundred parts water. Inasmuch as the overwhelming bulk of solids is carried off in the form of the paper web, the dilution of white water will be obvious. In point of fact, it frequently amounts to only one and one-half pounds of solids to one thousand gallons of white water. Under this condition there is little or no tendency on the part of the carbonate retained in the white water in the overflow box to deteriorate the alum. Naturally, the clarified white water obtained after filtration represents very largely a mild alum solution. When this clarified white water is used to dilute the pulp, or for the purpose of dumping the bleacher, or to wash the pulp in thev treated is placed in the beaters it has already been better and more thoroughly impregnated with alum than could be done by any ordinary beating operation. When carbonate is then added to the beaters there is no opportunity for concentrated bodies of alum solution to come in contact with concentrated masses of carbonate, and as a result there is no tendency to liberate large quantities of carbon dioxide due to reaction between the carbonate and the hydrolized alum.

Fig. 2 illustrates a system wherein even less alum is -utilized,. inasmuch as it is incorporated into the clarified white water at the white water sump, either by injecting a solution containing alum or by placing an ingot of alum in the sump. From there on the clarified white water passes to the samepoints of use and is taken into the system prior to the beaters and Jordans.

In both systems the reclaimed stock from the lter is taken back into the system preferably through the'rst filter chest so that the reclaimed stock and whatever chemicals, such as aluminum hydroxide, may be carried with the reclaimed stock and thoroughly incorporated into the mix in the Jordans and beaters.

It will be apparent from the foregoing that the alum is evenly distributed throughout the systemandisnot iniectedintothemixinanyconcentrated amount. in relatively small areas. The alum reacts to, a. certain extent with the reclaimed carbonate iiller to form aluminum hydroxide which is a coagulator, flocculent and mordant. This makes certain that more bres 5 will be caused to adhere to each other due to the intimate association therewith of the aluminum hydroxide and as a resulta stronger and finer interlocking of the fibres will be obtained. Each individual fibre will be more thoroughly coated with the mordant and greater color retention will result.

In the beaters the fibres are more or less stretched and caused to curl so that they will tend to interlock with each other. If, as in my process, 'the alum is intimately associated with the bres f before the carbonate is added there will be more of a filling action, and more of the carbonate filler will be retained in the web itself due to the substantial reduction in size and number of interstices between bres.

Whatever the correct theory of formation may be I have found that the resulting paper retains the filler to a greater extent than heretofore possible with a corresponding amount of filler, that less alum may be used since more of the alum actually used is put to practical effect, and that twosidedness is avoided. It is also found that due to the long, intimate association and mixing action, the harmful effects of foaming are avoided, which heretofore was thought to be impossible in any long mixing process. lbrcessive foaming is avoided due primarily to the fact that the pH value of the mix is such that the amount of carbon dioxide gas liberated by the action of the alum on the calcium carbonate can all be absorbed by the calcium carbonate forming an acid carbonate. Hence, it can be said that there is no actual liberation of carbon dioxide gas. I have found that the resulting paper is entirely uniform and free from lumps, spots and other defects, and that the paper has the desirable qualities to a high degree.

Other systems of arrangement of the various pumps, tanks and other portions of the system 45 may be utilized and I do not intend to be limited to those herein disclosed, except as set forth in the appended claims.

I claim:

1. In the method of making paper containing 50 te the elarined white water whieh is thereafter 55 returned to the system prior to the beaters.

2. In the method of making paper, containing a filler which is normally reactive with acidic material, the steps of filtering the white water returning the reclaimed stock to the beaters, adding alum to the clarified white water, and returning the clarified white water to the system prior to the beaters and washing the pulp therewith to thoroughly impregnate the fibres with alum.

3. In the method of malnng paper, containing a filler which is normally reactive with acidic material, the steps of adding alum to the white water, ltering the white water, returning the reclaimed stock to the beaters, and returning the clarified white water to the system prior to the beaters, and washing the pulp therewith yto thoroughly impregnate the fibres with alum. 4. In the method of making paper containing a filler which is normally reactive with acidic menemhescepetwuhmnhenbruwhan alum solution prior to their introduction into beaters.

5. In the method of making paper containing a iiller which is normally reactive with acidic material, the step of washing the fibres with an alu'm solution prior to their introduction into the beaters, and adding calcium carbonate to the alum-impregnated bres in the beaters.

6. In the method of making paper containing a filler which is 4normally reactive with acidic material, the improvement whichh lconsists ott passing an alum solution through the pulp prior to its introduction into the beater.

7. In the method of making paper containing a filler which is normally reactive with acidic material, the improvement which c'onsists .of passing an alum solution through the pulp prior to its introduction into the beaters and adding the calcium carbonate to the resulting alum-impregnated libres in the beaters.

8. A methodfor the manufacture of paper com taining an acid reactive 1111er comprising the steps of adding acidic material to the claried white water, adding the said waterto a brous mix at a point in the paper making system -prior to the beaters, introducing said mix into a beater and then adding an acid reactive ller.

9. A method for the manufacture of paper, containing an acid reactive ller which comprises -the steps of treating' the white water with an acidic material, separating the bres in the

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