US2871770A - Paper making machine - Google Patents

Description

Feb. 3, 1959 J. A. JACKSON PAPER MAKING MACHINE 2 Sheets-Sheet 1 Filed April 17, 1956 JESSE A. JACKSON INVENTOR. 8%.

ATTORNEY J. A. JACKSON PAPER MAKING MACHINE Feb. 3, 1959 7 2 Sheets-Sheet 2 Filed April 17, 1956 Frc l llll JESSE A JACKSON INVENTOR.

BY ATTORNEY res This invention relates to paper making and has for its principal object the provision of a method and apparatus for high speed, continuous production from high density stock of a sheet having high strength, low porosity and improved stability in the presence of liquids. A further object of the invention is to avoid the use of great quantities of water which up to now have been believed inseparable from the formation of all grades of paper.

An important object of the present invention is to secure higher speeds of paper production by forming the sheet directly from a high density stock instead of. from a suspension of fibers in a large quantity of water. A still further object of the invention is to transfer fibers by air or vapor pressure from the surface of a rotating permeable roll so that they will be plastered against a proximate moving belt which may, but need not, be per-' meable, the transferring medium preferably being a fluid at a temperature such that the fibers will be dried almost immediately,vthus sticking together as a firmly cemented, compact sheet on the beltor roll which forms the web forming device.

A still further object ofithe invention is to produce a newtype of strong, tough paper resembling parchment which will have a high resistance to wetting. Synthetic resins and/ormineral fibers may be added to this sheet. 'On a conventional papermachine the stock is carried in large I quantities of water. The Wet felted sheet is formed on cylinder molds or a Fourdrinier wire,,at.whicl1 time most of the water is drained away. The sheet then is carried .by felts through pairs of press rolls which squeeze out more water. The sheet then is carried around large numbers of steam heated rolls to complete the drying of the paper. This machinery is designed toperform the same operations as were originally invented by the Chinese, except thatthe drying was done then by spreading the hand made sheets in the sun. I i

' Bonding between the fibers in papermaking is dependent on the surface tension of the fibrillae, which "causes them to cling together strongly as they dry wherever'they touch. To bring this about, the fibers must be so arranged as to give an optimum number of contacts between adjacent fibers. In order to do this on conventional machines, the fibers are carried at a low consistency (5% air dry or-less) 'so they'will spread out in an even layer and interlace uniformly with each other while most of the excess water drains away. The rapidity with which this-can be done is limited strictly by the means which is employed to drain away as much as possible of the excess water; i. e., the .Fourdrinier wire With its table rolls, suction boXes,-and suction couch roll, or in the case of the cylinder machine, thewire mold with its diiference in level between the outside and insideof the cylinder.

After the fibers have been deposited on the wire or cylinder, the loose wet mat must be carried tenderly by felts through pairs "of presses which compact, it inorder to the fibers. The speedwith which this can be done is increase the number and intensity of the contacts between I atent O 2,871,770 Patented Feb. 3, .1959

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moving as much of the water as possible because of-t'the.

higher cost of subsequent water removalin the ,dryer section. The presses must accomplish their purpose with-, out disrupting the interlaced arrangement of the fibers;

Present day paper machines, for all their high produc: tion, have long since reached the limits of their capabili= ties. Any further increases withpresent-types .ofmachines will be limited to minor advances of the same kind;

as in recent years, such as greaterwidth, longer wire part, increase in the number and complexity of the press parts, and increases in the number of the dryer rolls.

In order to make any really significant advance in the art of papermaking, we must now break away entirely, from the present mechanism, and form the sheet directly without having to carry the fibers in largequantitie'szof water. This will not only permit higher speedsof production but at the same time will reduce the amountgof water still in the sheet after the formation occurs. H r,

In this invention, the time element involved in getting t rid of theexcess water is eliminated by forming the sheet directly from high density stock; say 15% air dry or more. In other words; forming it of fibersfrom which all the water has been previously removed exceppthe inter-cellular water and a film of water on the surface of each fiber in which the surface fibrillae have become partially dissolved. Accordingly, the fiber. surfaces are j in .a hydrated conditionso that when they. are thrown together by being sprayed. against a movingsurface, the

cellulose molecules are brought sharply into close contact and thus adhere by colloidal solution until .subse: quent drying cements the fibers together into -a ,s tr ong and permanent bond. This action is quicker and more positive than in the conventional paper machine, where the fibers are held together only by gravity after the water drains away and until the presses have compacted the sheet. Furthermore, the web is drier, thus elirninae ing the necessity forQthe conventional presses ,Whiqh squeeze'the sheet, and the press felts which cushion the sheet while performing their other functions of support and water removal. I 1 These considerations apply .to the use of thisinvention for the manufacture of all ordinary gradesofi paper'and also of a new parchment-like material which l call ffhot sprayed paper. The production of this uniquematerial is brought about by the use of a hard pulpfi. e.,: one which has not been cooked quite as drastically, hence, leaving some of the lignins undissolved. This typefof material, together with somewhat higher temperatures of the stock and of the moving surface on which the Web is formed, causes the plasticizing or searing of the'fibers into a stronger, more water resistant sheet. In addition,

special heat seal papers, incorporating afpercentage 'of;

synthetic fibers such as vinyl resin, can bemost advantageously made on this machine, using directly the' higher most eflieaciously produced from a so-called hard pulp,

and more specifically from an alkaline process pulp which has been given a relatively short cook at about 350 F., with effective alkali below 10% expressed as sodium oxide in pounds per pounds of wood, and with a correspondingly low sulphidity of the cooking liquor in order to produce a partly de-lignified fiber of high strength and yield. This type of pulp permits the use of the high temperatures of the hot spray process without degradation of the .cellulose, and sharply reduces the pulp preparation costs. Also, residual lig'nin is hydrolized only on the surface of the fibers, thus leaving its natural insolubility to add to the Wet strength of the finished product. In effect, this takes advantage of strength properties of the material which are usually destroyed in conventional pulpmaking.

In the accompanying drawings:

Figure 1 shows an elevation view of a complete machine embodying my invention.

jections formed on the outer surface of a woven wire version of the pick-roll of Figure '2.

Figure 7 shows another version of projections as a modification of those shown in Figure 6.

Figure 8 shows an edgewise view of an alternative design for the perforated plate pick-roll.

Figure '9 shows a plan view of the projections of Figure '8.

Figure shows an embodiment of the invention whereby a high density stock is sprayed directly at high pressure against a moving surface, without employing a pick-roll.

In operation, the pulp is discharged from pipe 1 into the head box 2 of-a decker or thickener 3 where it is dewatered by means such as the wire cylinder mold 4 and the drop leg 5. A continuous layer of dewatered fiber 6 is removed by take-elf roll 7 and delivered at a uniform rate down the chute 8 to pick-roll J. This is a hollow cylindrical mold of woven wire or perforated metal having on its outer surface a multiplicity of projections 10 designed to catch the fibers from the advancing edge of the layer 6. This cylinder is mounted on bearings 11 at each end, and rotatable on a fixed hollow shaft 12. The ends 13 of the cylinder 9 support bars 14 (Fig. 2) which are stiffened intercostally by rings 15. Bars 14 furnish an open support for the woven or perforated shell 16 of the mold or pick-roll 9.

Mounted internally of the cylinder 16 is the nozzle support manifold 29 which extends the full width of the roll lengthwise and is held in fixed position by hollow arms 30 fixed to the hollow shaft 12 at each end. Dry steam or hot air under pressure is introduced through hollow shaft 12 by means of a rotating joint (not shown) and is carried through the hollow arms 36 to the nozzle support 29 and is projected by a plurality of nozzle openings 31 through the openings of the cylinder 16 to remove forcibly the fibers from the projections 10 and spray them against the moving surface of belt 32. The fibers are thereby caused to be deposited on the surface in a substantially flat layer, interleaved and crisscrossed with each other in a random manner. Due to the heat of the surface and the heat of the steam or hot air, most of the moisture is driven 01f, the fibers adhere strongly to each other, and a firm compact sheet is formed.

The heat of the steam or hot air blowing from the jets 31 contributes to heat and dry the fibers instantaneously, causing them to stick together to form a compact sheet. The nature of the cellulose fiber is such, that when it is moist and hot, it has a natural tackiness or softness which makes it stick to other fibers with which it comes in contact, and when dried these fibers are even more firmly cemented together. This is at the heart of the paper making process, regardless of the means used to accomplish it. It is obvious that other means of subsequent drying, such as conventional steam heated rolls or other means, could be used with the above described. means for forming the sheet.

In the embodiment shown in Figure l, the belt 32 is mounted on rolls 33 and 34 and is driven through roll 34 by any suitable means. As the sheet of paper 35 is carried on the moving surface of the belt 32 it may be pressed by roll 36 and calendered by roll 3'7. Further drying may be accomplished, if desired, by means such as the infra-red burners 38, while the vapor driven off may be removed by the hood and exhaust system 39. 'Additional support for the moving belt may be furnished by a set of table rolls 40. Additional heat may be furnished for the moving belt 32 by additional heaters 41 at the returning portion. Means for keeping the belt tight are furnished by the rolls 42. At the point where the sheet 35 is formed, steam and vapor may be collected by the hood 45 and the exhaust fan 46. The finished sheet is removed from the belt 32 by means of a doctor 43 and is continuously wound on the reel The linear speed of the layer of pulp on the projections of the pick-roll 9 must be carefully adjusted relative to the speed of the moving surface 32 in order to deposit the correct amount of fiber for the weight of paper being made. The amount of fiber carried on the projections 10 is determined by the length of the projections, the number of projections per unit of area, and the speed. For a pick-roll with a given spacing of the projections lit, the linear speed will be considerably above the speed of the moving surface 32, and should be at least one and one-half times as fast or higher, depending on the spacing of the projections and the average length of fibers in the stock. The speed of the decker roll 4 must also be carefully adjusted in order to feed the layer of pulp 6 down the chute 8 at such a rate as to discharge the correct amount of fiber to the pick-roll 9. The best linear speed of pulp layer 6 is about one-twentieth of that of the moving surface 32.

To prevent centrifugal force from raising the fibers on the pick-roll 9, a smooth curved shield 54- may be installed as shown in Figure 2. To prevent a similar centrifugal action from affecting the formed sheet 35, a similar shield may be installed over the support roll 33, or a moving belt of heat-resistant fabric or plastic cloth may be installed as at 55.

The arrangement of the nozzle openings 31, as best shown in Figure 3, indicates how two or more rows may be directed to a common line 47, in order most effectively to remove the fibers from the projections 10. This permits the use of more nozzle openings than could be accommodated in a single row, and also allows the openings to be staggered laterally the more evenly and completely to remove all of the fibers from the pickroll 9.

Figures 4 and 5 illustrate a form of plate shell 16 for the pick-roll 9 which has perforations 18 with a type of projections 17 formed of small wires; these wires 17 being spaced evenly between the perforations 18, and fastened to the shell by welding, or by riveting in small holes, as desired.

Figure 6 shows a method of attaching projections 20 to a woven wire form of shell 19 for the pick-roll 9. Here, the projections 26 are made from U-shaped wires which are inserted over the woven wires of the shell and crimped or twisted together to hold them in projecting alignment. Figure 7 shows an alternative of the method of Figure 6, whereby the U-shaped wires 22 are made wider to span across two or more adjacent wires of the shell wires before being crimped as at 21. With either of the methods of Figure 6 or Figure 7, the U-shaped wires may be inserted diagonally across the interwoven wires of the shell, if desired. Another alternative method would be to braze the wires in place, instead of crimping them.

Another method ofconstruction of the pick-roll 9 is shown in Figures 8 and 9, where the projections 23 are formed in a thin plate shell by a special punch and die which cuts the openings 24 and bends the material out, leaving each point attached as at 25.

In theembodiment shown in Figure a continuous layer of dewatered fiber 6 is discharged by means of takeoif roll 7 and chute 8. This high-density stock is discharged to a suction chest 26 in order to provide a positive head of at least feet on the suction side of stock pump 27. When space permits, the height of the column of stock in the suction chest 26 is sufliciently great to eliminate voids in the material, otherwise a gentle agitation may be supplied by screw 48 driven from any suitable means attached to shaft 4,9. Further elimination of trouble from minute quantities of entrained air enmeshed in the fibers may be accomplished by introducing low pressure steam, say 10 p. s. i. or less, through inlet 50 and an array of small openings in a manifold 51, in order to raise the temperature of the stock and thus keep the air insolution. The pump 27, since it is to handle high-density stock, should be a wide bladed centrifugal pump designed for this service. There are several makes of centrifugal stock pumps on the market, which, for high consistencies, are provided with special agitator blades at or near the impeller inlet to keep the fibers evenly distributed in the stock. This pump should provide at least 100 feet of head and a capacity of at least six gallons per minute per inch of width of the machine.

Once the stock is on the discharge side of the pump it moves at high pressure through connecting pipe 52 to a manifold 28 extending across the face of the moving surface 32. A slice opening 53 in the manifold 28 allows the high-density stock to be sprayed directly against the moving surface 32, forming a continuous sheet 35, as in the embodiment of Figures 1 and 2. Speed regulation of the pump 27 should be provided, in order to permit'adjusting the quantity of stock flowing through the slice opening 53. The slice opening 53 may also be made adjustable, as is done in a conventional head box.

The layer of stock which is sprayed from the slice opening 53 causes the fibers to be deposited in a substantially flat layer on the moving surface of the belt 32, interleaved and criss-crossed with each other in a random manner. As the fibers impinge against the heated surface of the belt 32, a substantial part of the moisture is driven off while the remainder may be removed by subsequent drying means such as the infra-red burners 38 and the hood and exhaust system 39. An optimum efiiciency of this moisture removal may be achieved by elevating the temperature of the stock to the highest practicable point as it goes to the manifold 28 and the slice opening 53. This may be accomplished by adding a small quantity of steam to the stock through the small pipe 59. This steam should be regulated to about 3 to 5 p. s. i. above the discharge pressure of the pump 27, or approximately 45 p. s. i. g. and at least 300 F.

For either embodiment, the belt 32 and rolls 33 and 34.- may be replaced by a single large diameter roll, with heaters 38 or 41 adapted to suit. The speed of the moving surface determines the daily tonnage output of the machine. From the nature of the spray means of forming the sheet, there is no practical limitation to the top speed that may be used, other than the structural strength and rigidity of the supports, and the size and weight of the moving parts.

What I claim is:

1. In a process for the manufacture of paper sheets wherein a fibrous stock is lightly deposited on a webforming device, the step of blowing a paper-making stock having a consistency greater than 8% against the webforming device by means of a vapor heated to a temperature at which the thus-formed Web will be a firmly cemented sheet as it strikes the web-forming device.

2. The method of forming a paper sheet which consists in blowing a relatively dry, high density hard pulp paper-making stock upon an endless carrierat. a temperature above 300 F. and .at apressure exceeding p. s. i.

3. The method of claim 2 in which-the temperature are blown to theweb-forming-device are partially in colloidal solution.

5. The process of claim 1 in which the web-for ing device is a single heated endless belt forming a dryer.

6. The. process of claim 1 in which the stock contains synthetic fibers. Y i

7. Thedevice of claim 1 in which the'stock contains mineral fibers. I I 8. The process of claim l'in which the'stock contains less than 10% elfective alkali.

9. The method of claim 2 in which the paper sheet is tacky and is heated while supported by the web-forming. device. I

10. The process of claim l-in which steam is'added to the stock immediately prior'to its'being deposited on the web-forming device. I

' 11. A paper making drum comprising 'a foraminous cylinder having short radial projections, each projection being proximate an opening in the cylinder.

12. A paper-making drum comprising a wire mesh cylinder and a plurality of short Wire pieces each secured to the cylinder and having two free ends projecting radially from the cylinder. 7 I i 13. The drum of claim 12' in which each short wire engages at least two transverse'strand s' of the wire mesh.

sheet of paper stock from the decker and depositing same on the chute, a pick-up roll receiving the sheet of fibers from the chute, means within the roll'for'blowing the sheet of fibers from the roll in a radial direction and a web-forming device for receiving the sheet from the pick-up roll.

15. The device of claim 14 in which the pick-up roll includes a wire mesh cylinder having radial projections.

16. In a paper making machine, a web-forming device, a foraminous drum spaced closely thereto and having short radial projections, each proximate an opening in the drum, means for depositing a stock having a consistency greater than 8% on said projections, and means for blowing vapor through the openings to convey the stock to the web-forming device, said vapor being at a temperature at which the thus-formed web will be a firmly cemented sheet as it strikes the web-forming device.

17. The machine of claim 16 in which web-forming device is a heated endless belt forming a dryer.

18. The machine of claim 16 with means for heating the paper sheet while supported by the web-forming device.

19. In a process for the manufacture of paper sheets wherein a fibrous stock is deposited on a web-forming device, the steps of supporting a stock having a consistency greater than 8% on a plurality of points arranged in cylindrical form, and directing a stream of dry steam radially of the points to transfer the stock to the webforming device as a firmly cemented sheet.

20. The method of transferring a layer. of paper stock from a foraminous cylinder having short radial projections each forming a point proximate an opening in the cylinder to a heated endless belt forming a dryer which comprises blowing a vapor through the openings of the cylinder at a temperature at which the web formed on the belt will be a firmly cemented sheet.

21. In a method for making paper by depositing a thin layer of paper pulp on a web-forming device with minimum use of water, the steps of producing a partly de-lignified fiber mass from an alkaline process hard pulp, giving said mass a relatively short cook at about 350 F., with-effective alkali below ten percent, expressed as sodium oxide in pounds per hundred pounds of the wood, dewatering the pulp and delivering the dewatered fiber at a uniform rate in a multiplicity of particles, blowing said particles against a surface by means of a heated fluid to spray a thin layer the width of the surface, the heat of the fluid being such that the major portion of the moisture is driven off and a firm compact sheet is formed on the surface.

22. The method of transferring a plurality of paper pulp fibers positioned in cylindrical form and depositing them as a thin layer on a web-forming device which comprises, blowing the fibers radially against the moving web-forming device by a heated fluid while concentrating the flow of fluid so that the fibers are deposited on the web-forming device in a single line parallel to the axis of the cylinder of fibers.

23. The method of transferring a mass of paper pulp fibers arranged in cylindrical form to a web-forming device including the steps of directing tWo thin wide streams of a hot fluid against a single line of the cylinder parallel to the axis and moving the cylinder of fibers and the web-forming device so that the paper pulp fibers will be deposited on the web-forming device as a thin layer of uniform thickness in which the fibers are interleaved and criss-crossed with each other in a random manner.

24. In a process for the manufacture of paper wherein a fibrous stock is deposited on a web-forming device, the steps of giving an alkaline process hard pulp a short cook at about 350 F. with effective alkali below ten percent, depositing the partly de-lignified fiber particles to form a hollow cylinder, moving a surface tangential to said cylinder proximate thereto, directing a plurality of streams of heated fluid to the interior of the cylinder to blow the pulp fibers against said surface to deposit the fibers on the surface as a substantially flat layer with the fibers interleaved and criss-crossed with each other in a random manner, the heat of the fluid being such as to dry the fibers substantially instantaneously, causing them to stick together to form a compact sheet on said surface, dewatering the sheet, calendering the dried sheet, and winding the sheet on a roll.

25. The method of increasing the rate of production of paper by minimizing the use of water which includes suspending particles of high density stock on a multiplicity of points arranged in cylindrical form and blowing the particles successively from said points to a moving surface at such temperature and pressure as to form the paper sheet direct from the stock upon striking said surface.

26. In a paper-making machine, a decker, a pick-up roll, means for conveying fiber from the decker to the pick-up roll to form on the pick-up roll a thin hollow cylinder of fibers, a belt proximate the pick-up roll for receivin the paper stock from the pick-up roll, means within the roll for forming two separate streams of a hot fluid meeting in a line proximate the belt and parallel to the axis of the cylinder, whereby as the pick-up roll is revolved with the belt, the fibers will be deposited on the belt as a single layer.

References Cited in the file of this patent UNITED STATES PATENTS 598,241 Case Feb. 1, 1898 1,897,479 Hopkinson Feb. 14, 1933 2,140,189 Mason Dec. 13, 1938 2,208,511 Ellis July 16, 1940 2,341,623 Kern Feb. 15, 1944 2,362,450 Chappel Nov. 14, 1944 2,447,161 Coghill Aug. 17, 1948 2,696,146 Chapman Dec. 7, 1954

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