US2044281A - Paper manufacture - Google Patents

Description

June 16, 193.6.

J. DA, CLARK ET AL PAPER MANUFACTURE Filed Sept. 24,. 1931 gwuentoz [4M dQ Jaw,

Patented June 16, 1936 UNETED STATES PATENT eerie 1 2,044,281 PAPER MANUFACTURE Application September 24, 1931, Serial No. 564,790

11 Claims.

This invention relates to the manufacture of.

paper; and one of the principal 'objects of the invention is to provide a method of forming paper which includes effecting controlled formation as to the opposite sides to produce a formed sheet or web of paper of hitherto unknown and superior characteristics.

Another object of the invention is to provide such a method in the formation of a paper sheet which produces paper free from two-sidedness. Still another object is to provide as a superior product a paper formed with controlled body and surface characteristics, of adequate strength.

Another object of the invention is to provide apparatus for carrying out this method and-producing such a product, which is simple in iconstruction and efiective in operation.

Other objects and advantages of the invention will be apparent from the description thereof set out below and from the accompanying drawing and from the claims.

Reference is made to an application of William Edison Bair, Jr., Serial No. 521,118, filed March 9, 1931, Patent No. 1,875,208 issued August 30, 1932, and to the copending application of James dA. Clarkand John E. Graves filed August 7, 1931, Serial No. 555,757, now Patent No. 1,950,351, the invention hereof having to do with the practicing of the inventions of the said applications.

In the drawing, in which like characters of reference designate like parts throughout the several views thereof- Fig. 1 is a View, largely diagrammatic, of a paper machine having the invention hereof embodied therein;

Fig. 2 is a view, also largely diagrammatic, showing a modified arrangement for adding the filler suspension; and

Fig. 3 is a view showing still another modified arrangement for adding the filler suspension to the wire side of the fibrous web.

As is well known in the manufacture of paper it is the general practice to bring the paper forming stock onto a forming wire-such as the traveling wire of a Fourdriniermachine,through' which the water may pass leaving a web or sheet of matted fibers upon the wire. The stock constituency varies according to the operating cir- 0 cumstances and the end product desired, and

comprises pulp made from the properly separated fibers of wood, or the like suspended in water, with admixed filler, size, etc. It is a very general practice, particularly where paper of a better grade is to be made-such for example as is used are stopped and other finer materials.

for book or magazine printin ,-to admix with the fibrous suspension .a considerable proportion of finely divided clay or other filler, size or other constituents; the materials and the proportions thereof used varying somewhat according to the character of sheet desired. While the stock is on the forming wire some of the water escapes through the wire, the fibers remaining to form the web or sheet of paper which is subsequently removed from the wire and subjected to additional treatment, such as pressing, drying, calendering', coating, and the like.

With particular reference to a Fourdrinier machine, which type is illustrated in the drawing for purposes of description, as the stock is flowed onto the wire there is q through the wire during the travel of the stock upon the wire, and some of the finely divided filler and other finely divided constituents, and some of the finer fibers, tend to flow away with the water through the forming -wire. A large part of so much of the water of the stock as ultimately escapes through the forming wire before the formed web is removed therefrom, escapes before the suction boxes are reached, partly under the action of gravity and partly due to the action of the table rolls. The remainder of the water which is removed before the forming web is taken from the wire is removed during the remaining distance of travel of the wire, particularly while it is passing over the suction boxes and while it is passing over a suction couch roll, if such is used. As the stock flows onto the wire the greater portion of the fibers by the wire and matted thereon forming a filtering mat or web through which the remainder of the water passes or is drawn to escape through the wire side. The table rolls as they revolve carry around a film of the escaping water which tends to further wash out filler Also at the suction boxes the suction tends to withdraw some'of the filler, etc. with the removed water; and the same thing istrue at the suction couch roll. A paper sheet as heretofore so formed ordinarily has different surface characteristics on its opposite sides. The wire side difiers from the opposite or upper side both in texture and appearance; this condition of difierent surface characteristics being knownin-the industry as two-sidedness. In

the formation of the sheet, with all of the water being drawn downwardly ,or through the sheet in one direction to escape through the wire, there results a non-homogeneous distribution of the filler, and of the fiber also, within the sheet. As

tea rush of water first few feet oflack of homogeneity, and the a result the fibers of the upper side are generally finer than those on the wire side giving different textures and appearances to the opposite sides. Also the relative quantityof retained filler, etc. decreases from the top side to the wire side, which may have substantially no retained filler. This exaggerating of it which attends in progressing degree upon the use of increased quantities of filler, is universally recognized in the industry as is also the fact that the practicable limit of differentiation in the two sides definitely limited the proportion of filler that might be contained in a sheet. That is, if the two-sidedness becomes too marked the sheet has utility,or, at least, its marketability and commercial value are seriously even if not destroyed. Two-sidedness is also more marked, other conditions being equal, when the filler used varies materially in color characteristics from the stock used. This is especially true with book paper, such as is used for magazines and the'like. It has heretofore been ordinarily considered commercially impracticable to provide as much as 25% on the dry weight of the fiber, in the finished sheet, and st secure paper suitably usable on the score of two-sidedness. Even with 20% of filler it has been very diificult to maintain the of filler surface increases. Also, as the filler is probably h Cheapest gredient going into the stock, from a commercial point of view it is desirable to minimize'the amount of pulp,using so much fibrous material as is as to produce new surface characteristics with the wire side approximating the top side charactofore experienced.

For purposes of description, and as setting out a form of mechanism which will operate in a very satisfactory manner'for the carrying on of the method of this invention and the producing of the new paper product, a conventional form of Fourdrinier paper making machine is illustrated in the drawing, largely indiagrammatic form. In the drawing the numeral l designates generally the frame of the wiresection of the paper making machine, which frame carries the usual forming wire ll supported by a breast roll l3,.and

a. couch roll I! preferably of the suction couch supplying inlet or means may be utilized, such means being shown diagrammatically and designated by the numeral I 5. The numeral l6 designates the dandy roll just beyond which are located the suction boxes l1. Located between the suction couch roll l4 and the suction boxes I! is the wire guide roll 20.

' In accordance with the present invention additional forming material is applied to the wire side .of the paper, afterit has arrived at a sufiiciently penetration decreasing inwardly.

definite stage of formation. When filler suspension is applied under such conditions of dryness of the web that the liquid of the forming material suspension is readily absorbed by the wire side of the sheet it will carry the filler, etc. 5 into the interstices-into the body of the sheet, where it will be deposited and retained, some being also retained in and on the fibers at the surface of the web. In the type of machine shown in the drawing this definite or initial stage 01' formation is ordinarily reached during the passage of the forming sheet or web over the suction boxes, and-the condition is indicated by the web losing the liquid appearance which it has up to that stage. When the forming paper web moves up to the regular suction box zone it gives the appearance of a pool or sheet of water suspension, but as the wire moves along the watery sheen or glitter disappears as more water is removed, until the sheet as it assumes its initial definite form has the appearance of a damp or moderately wet sheet of paper. This change usually occurs as the web passes over the suction box zone, but whatever the precise it is an easily recognized change. In actual commercial use of the invention it was found that as the initially formed sheet moved away from'the last suction box it contained from 14 to 19% of solids-or 81 to 86% of water. At this stage the sheet, as stated, is sufiiciently definite in form and has sufiicient water absorption capacity to permit of practicing the present invention. Actual commercial prac-- tices also show that the above described change in the sheet probably takes place when sufiicient water has been removed to leave approximately 90% of .water and 10% of solids in the forming web.

When the invention is paratus shown in Fig. 1 mechanism is positioned to act upon the traveling passes to the first press. As shown in Fig. 1, this mechanism comprises an endless belt 25 which may be of felt, or of wire such as forms the wire of the Fourdrinier part of the machine, but preferably of a much stronger and coarser construction, which runs over suitable rolls 26, the mechanism being so supported that the paper sheet 3', which has been picked oil? from the couch roll in the usual way, passes over the fiat portion of the endless belt 25, after which it passes on and is picked up upon the felt 3| to be carried through the first press, which is shown diagrammatically. and designated generally by the numeral 32, and is then passed on through the remaining-presses, etc. in the usual manner. The endless belt 25 of wire or felt has positioned beneath it a slotted pipe 35, to which added forming material may be supplied, this material passing up through the slot, through the wire passing thereover, and onto the wire side of the paper web, as a result of which additional filler or surfacing material will be embodied into the web. The web at this stage being sufiiciently free from water to be quite absorptive, the water of the suspension material will be drawn up into the web carrying the filler or other solid suspension ma terial with it and as a result the suspension penetrates into the body of the web, the degree of tration-to a considerable distance, and the penetration seems to so decrease that the e is no abrupt change or line of cleavage where t penetration ceases. By properly proportioning the approach the characteristics of the other side of the web as to actual texture, susceptibility to printing, apparent surface characteristics, etc. In addition to deeply penetrating the sheet, the filler is also deposited and held on the surface fibers so as to whiten the wire side and give that side the same appearance as the other side. The effect in this respect is as if the wire side had been whitewashed to bring it up to the same appearance of whiteness as the other side. In actual commercial operations the appearance of the wire side of paper formed according to this invention so closely approaches in characteristics the upper side that there is no evidence of objectionable two-sidedness.

' the web is avoided and the finished sheet will have as great strength as if it had been formed in the heretofore usual way.

Preferably a constant head box, not shown, is provided to supply the filler suspension to the slotted pipe 35, this head being proportioned according to operating conditions, the head being increased as the speed of travel of the machine increases, in order to supply the additional quantities of suspension material that would be needed under increased operating speeds. Also the slot in the pipe is preferably positioned to one side of a vertical plane passing through the axis of the pipe, and on the couch roll side of such plane, so that the slot opens against the direction of travel of the oncoming wire. With suitable head .the suspension material may be fed up through the wire so that there is no overflow, all of the suspension material going onto the wire, and through the wire onto the web.

Positioned beyond the slotted pipe is a vacuum or suction box 55, which may be of usual construction, and which serves to remove from the paper web, as it passes over the vacuum box t5, some of the water absorbed by the web as it passes over the slotted pipe. Only one such vacuum box is shown in the drawing but the number of boxes may be increased if desired. This vacuum box 65 should preferably be provided with slots, which are so arranged as to present an uninterrupted opening all the way across the web, the suction exerted being thus uniformly exerted upon the wetted sheet, to cause a uniform withdrawal of water, and filler or suspension material, therefrom. This uniform suction upon the sheet is advantageous and tends to prevent an irregular appearance to the finished sheet, which otherwise sometimes occurs where the suction after the added suspension material is applied, is not uniformly distributed.

In the form of construction shown in Fig. 2, the filler suspension is added to the paper web after it passes from the couch roll to the first press. In this construction, however, the color is supplied to a trough 50 within which is positioned a roll 51, which dips into the color during operation. This roll 5! is associated with rolls 2% which support the traveling belt of wire or fel generally similar to that described above incor nection with Fig. 1, upon which belt the web of paper rests as it travels from the couch roll to the press felt. Positioned between the rolls 2.6

Ban air blast, with jets or openings arranged to discharge air upwardly through the wire or felt against the wire side of the paper web 30'. During operation the suspension material within the trough is picked up by the wire or felt as it passes over the roll 5! and carried up against the traveling web of paper, the air blast serving to blow "this material out of the felt or wire onto the wire side oft-he paper. The air blast may-sometimes be sufliciently strong to lift the paper web somewhat from the wire as indicated at 53. The paper web with the suspension material thus applied to the lower surface then passes on through the presses, which may be of the suction press type, where the additional water taken up by the paper is removed and the suspension material left a in position, as described above. a

In the form of construction in Fig. 3 a traveling felt 25" is utilized for applying the suspension material to the Wire side of the paper. In this construction also a trough 50' for the suspension material is provided. In this arrangement,

however, the web of paper passing from the couch roll travels through a pair of squeeze rolls the upper of which is designated by the numeral fill and the lower by the numeral 6|, which rolls are adjustable as to pressure.

The felt 25" runs over the lower roll 6|, the web of paper thus passing between the two rolls and being in contact with the felt and with the upper roll. During operation the felt passin through the suspension material within the trough 50' picks up some material and carries it up where it is deposited on the lower or wire side of the web at the nip of the rolls 60 and BI. of squeeze rolls 5! and 52 are provided so that after picking up suspension material the felt passes between these squeeze rolls which are so adjusted as to control the amount of suspension material carried up to the nip of the rolls GIL-6 I. By suitably adjusting the pressure of the rolls 60 and BI and rolls 5| and 52, control of the amount A pair of suspension material applied to the paper may may be provided with a continuous supply of new material, and with a constant level overflow.

In the forming of paper sheets the stock originally supplied must contain a considerably greater quantity of filler, etc., than will appear in the ultimate product. In actual operations it has been found that to secure a finished sheet having 25% filler, about of filler, on the fiber content, should be added to the stock. .-But without the practicing of this invention such proportion of filler in the finished product would give evident and marked two-sidedness.. In the practicing of this invention the percentage of filler contained in the stock has been increased to about of which about 27% remains in the finished sheet. Satisfactory results, with substantial elimination of two-sidedness, have been secured where the material within the trough 50 consists of a suspension of a carbonate, or other similarly acting filler in water, containing 22 pounds of carbonate filler and 3 pounds of size, such as boiled starch, in

above specified which would give approximately 27% of filler in the finished sheet, by adding the suspension material as described an additional 1 to 2% of filler will be included with the elimination of two-sidedness. It has been found that the amount of suspension material withdrawn at improved as to its two-sidedness, even if the size is omitted, but the strength of the sheet and the bonding of the added filler to the sheet will be materially improved if the size is added. It has been found in actual operation in the manufacture of high grade book paper, utilizing the addition of filler suspension to the forming web in the manner disclosed in this application, and also in the patent of William Edison Bair; Jr., No. 1,875,208 issued August 30, 1932, and filed March 9, 1931, and in the copending application filed August 7, 1931, Serial Number 555,757, above referred to, that the final sheet will suffer a decrease in strength of approximately 10% if the size is omitted and that the surface particles -of filler will not be as well bonded to the sheet; but by the addition of suitable size for example as specified above, this decrease and lessening of the bonding will be prevented and the finished sheet will have characteristics as to strength and bonding equal to those of a sheet formed out of the same pulp stock, etc., in the heretofore regular manner, and will in addition have the 'de-" from twosirable characteristics as to freedom sidedness, etc.

While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be underslood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

' What is claimed is: a

1. Apparatus of the character described, comprising a forming wire, means for flowing fibrous stock onto the wire to form the paper web, a traveling pervious belt beyond the wire for receiving the formed web from the forming wire, a trough adapted to contain surfacing material, means for guiding said belt so as to travel within the surfacing material within said trough and thereby pick up a portion of said surfacing material, subjecting the felt to a controlled expelling force to limit the amount of filling material carried thereby, said belt being adapted to then contact with the wire side of the formed web to transfer a controlled portion of the remaining picked-up surfacing material to the .wire side of the web.

2. Apparatus of the character described, comprising a forming wire, means for flowing fibrous stock onto the wire to form a paper web, a traveling pervious member beyond the wire for receiving the formed web from the forming wire, a trough adapted to hold surfacing material, means for guiding said traveling pervious member so as to pass through surfacing material within said trough to thereby pick up a portion of the surfacing material, and a fluid blast for blowing picked-up surfacing material out of the traveling member onto the formed web.

3. Apparatus of the character described, comprising a formingwire, means for flowing fibrous stock onto the wire to form a paper web, squeeze 5 rolls through which said formed web is adapted to pass after removal from said wire, a traveling member for directly receiving the formed web from the forming wire and also passing through the nip of said squeeze rolls and in contact with 10 one side of said formed web, and means for supplying a limited amount of surfacing material to said traveling member, whereby said member carries the surfacing material into contact with said web and transfers the limited amount of said 15 surfacing material for incorporation into the surface of the web as they pass together through the nip of said squeeze rolls.

4. Apparatus of the character described for Y forming a paper web and adding filler material 20 to said web during the process of manufacture of the paper sheet, comprising a forming wire, means for flowing paper making stock onto the wire with resultant drainage through the wire to effect formation of aweb of paper, means com- 25 prising a traveling member passing 1m contact with the wire side of the web, and means for applying a delimited quantity of finely divided mineral material to said traveling member to be brought into contact with said web to incorpo- 30 rate the finely divided mineral material into the wire side and surface of the said web to be retained therein as additional filler material for said web,'said last named means being spaced from the forming wire. and positioned at a point 30 functionally remote from the-zone of formation of the web and of the rejection of paper forming materials within the forming wire zone, and to receive said web directly from said forming wire, to apply filler'material thereto while said web is 40 wet and in receptive state.

5. Apparatus for filling a paper web including a pan for a suspension of finely divided mineral material, vertically aligned pressure rolls, an endless band of absorbent material, means for feeding 45 paper web through the nip above said band, and '50 means for causing said rolls to engage the web and band under sumcient pressure to compress the band at the nip and squeeze a predetermined quantity of filling material from the band into contact with the paper web to be incorporated 5 into the surface stratum of the said web as it leaves the nip.

6. A process of filling a paper web as part of one continuous paper making operation, which comprises impregnating a felt with a controlled 60 quantity of filling material, subjecting the felt to a controlled expelling force to limit the amount of filling material carried thereby, passing the felt with the web thereon through pressure rolls under 'sufiicient pressure to expel part of the flll- 65 ing material from the felt at the nip of the rolls and force expelled filling material into surface contact with the said web to incorporate filling material into and upon the surface stratum of said web as the web passes between the pressure 70 rolls.-

7. A process of filling a paper web as part of one continuous paper-making operation, which comprises impregnating a felt with the filling ma- 8. Apparatus for filling a paper web, including vertically aligned pressure rolls, a pan for filling material, an. endless band of absorbent material, means for guiding said band through the filling material to impregnate the same,

' means for expelling a part of the'filling material from said band to delimit the amount of filling material carried thereby, means for guiding the impregnated hand through the nip of said rolls, means for guiding a paper web through the nip above said band, and means for causing said rolls to engage the web and band under sufiicient pressure to compress the bandat the nip and squeeze filling material therefrom into the path of the web on the entrance side of the nip.

9. Apparatus of the character described comprising a forming wire, means for flowing paper.

making material onto said wire to form a paper web, means for effecting partial removal of water from said formed web, means functionally remote from said web forming means for applying a suspension of mineral paper making material to be incorporated into and upon the surface of said formed web and concentrated in the surface depressions and interstices of the surface thereof, said means comprising a member traveling into contact with the moving web, means for applying a controled quantity of suspension of mineral paper forming material to said traveling member to be carried tnereby into incorporating contact with the traveling web, and means for controlling the incorporating application of said mineral paper forming material to the web, said means being effective to control the quantity of said mineral paper forming material applied.

10. In the manufacture of paper to effect a two-stage application of mineral paper making material to give controlled printing and finish surface characteristics, the process which comprises forming a web containing a predetermined proportion of the ultimately desired mineral constituents of the finished paper product, efiecting partial removal of water from said formed web, applying the controlled consistency suspension of paper making material to a traveling member positioned functionally remote from the zone of formation of said web, transferring said suspension of mineral paper making material in excess from said traveling member to one side of said formed web, and effecting a pressure removal of the excess of such mineral paper making suspension from the web to leave a predetermined quantity of such mineral material incorporated into and upon the surface of said formed web and concentrated in the surface depressions and interstices of the surface thereof.

11. In the manufacture of paper to effect a twostage application of mineral paper making material to give controlled printing and finish surface characteristics, the process which comprises forming a web containing a predetermined proportion of the ultimately desired mineral constituents of the finished paper product, effecting partial removal of water from said formed web, applying a controlled consistency suspension of mineral paper making material in excess to one side of said formed web, and doctoring off the excess of such mineral paper making suspension to leave a predetermined quantity of such mineral material incorporated for said printing and finish characteristics into and upon the surfacestratum of such web and within the surface interstices and depressions thereof.

JAMES- nA. CLARK. JOHN TRAQUAIR.

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