US2286924A - Manufacture of sheet material - Google Patents

Description

June 16, 1942. G, w, MCHOLSON 2,286,924

MANUFACTURE OF SHEET MATERIAL Filed Jan. 12, 1938 if f 2/ W oo LJUUk/IJJE II Patented June 16, 1 942 MANUFACTURE OF SHEET MATERIAL Gunnar W. E. Nicholson, Panama City, Fla., as-

, signor, by mesne assignments, to International Paper Company, New York, N. Y., a corporation of New York Application January 12 1938, Serial No. 134,525

' 1 Claim. (01. 92-40) My present invention relates to the manufacture of sheet material and, more particularly,

to the manufacture of paper of the built-up layer typeupon a Fourdrinier machine.

In the manufacture of certain types of multiply sheet material, it has been proposed to flow a layer of stock upon the wire of a Fourdrinier machine from a head-box located adjacent the breast roll. This layer of stock is partially de= hydrated as the wire passes over a series of devices, such as table rolls and suction boxes. An-v other head-box has been'mounted in a position along the wire to flow a second layer of stock upon the partially dehydrated layer already upon 7 the wire. If the dehydration of the first layer of stock has progressed only to'such an extent that the fibers adjacent the wire have been set or matted and the stock on the upper side ofthe layer is in watery condition at the time the second layer of stock is flowed thereon, the succeeding suction boxes will draw water from the second layer of stock down through the first layer which acts as afilter pad. The filtering of the water through the first layer will draw certain of the fibers in the second layer partially into the first layer and certain of the uppermost fibers of the first layer will be displaced and pro-; jected into the second layer to produce an interexample already given, it will be appreciated that there may be many instances in which interfelting of the fibers might be inadequate to provide an inseparable bond between the layers of a built-up paper, paperboard or other sheet material.

It is an object of my invention to improve the bond between successive layers of sheet material laid upon the sheet forming portion of a paper making machine.

It is a'further object of my invention to provide for the addition of any desirable stock modifying' material, such as a chemical, filler, a'dhesive or other substance in the zone of union between successively applied layers of fibrous material.

It is a specific object of my invention to provide for the formation upon a Fourdrinier machine of a homogeneously interfelted sheet. of

felting or interlocking of thefibers of the two layers. The two layers will therefore become integrally united and there will be no line of demarcation or separation between the layers along which peeling may occur.

In the practice of the process just outlined,

the degree of dehydration of the first layer must.

be very carefully controlled in order that a satisfactory interlocking of fibers will occur when a second layer is laid/thereon. The dehydration of the first layer must not be carried to such an extent that all of the fibers thereof will be perwhose fibers are very finely divided or which contains valuable fines or sizing, filling or coloring material which must not be drawn too deeply fibrous material whose. opposite surfaces may vary greatly in their characteristics.

It is a further object of my invention to provide apparatus upon which sheet material, having the characteristics herein set forth as desirable, may be formed.

It is a further object of my invention to provide sheet material having the characteristics herein set forth as desirable. I

According to my invention a layer of stock is laid upon the wire of a Fourdrinier machine from the lip of a head box in a well known manner. This layer of stock may be partially dehydrated and a suitable stock modifying material in aqueous or other solution suspension or mixture may be flowed thereon by means of a distributing device which uniformly distributes such material across the web. This material may form a protective or modifying coating for the layer or for the individual fibers within the layer, or may serve to size the upper portion of the partially dehydrated layer, or may serve-as an adhequently applied. Immediately after the aforesaid material is flowed uponthe partially dehydrated layer, a second layer of stock is laid into the first layerand, which of course must not be drawn through the layer and lost through the, wire. In such event, it is desirable that the stock in the first layer shall be well matted and dehydrated in order that it may effectively serve as a filter pad. Under these circumstances, in- I terfelting of the fibers in the respective layers .may not'be sufiicient to satisfactorily form a union between the two layers. In addition to the may have any desirable characteristics.

thereon by the lip of a second head bolx suitably supported above the wire. This second layer of stock may be of any desired type and The water in which this second layer of stock'is suspended is progressivelydrawn through the first layer and the fibers of the two layers may become interfelted and interlocked as abovediscussed. The modifying material applied by the distribinterfelting of fibers which has heretofore ren- -The provision of binding materi v ,the layers of stockenables me to form a satisfactory bond'between the layers irrespective of uting device will remain wi the zone oi union between the two layers and may serve in. various ways to improve the bond between the fibers of the respective layers.

pears that the resence of the sizing 6r adhesive material in the zone of union between the respective layers so improves the bond therebetween as to compensate for relatively inemcient dered such unions unsatisfactory. I

It will thus be seen that my invention may be particularly adapted for the production of a homogeneously interfelted'sheet comprising layers of fibrous materials which may vary widelyin characteristics. Thus, the first layer may comprise a free-slightly hydrated long fiber stock which will present a surface of aporous absorbent nature. For example, this layer may be a relatively undercooked, slightly beaten' kraft stock. This layer of stock may contain no size or may be sized to any desirable degree. A suitable binding agent, such as animal glue, sizing material, sodium silicate or latex compound, may be flowed upon the partially,dehydrated first layer. A second layer comprising astock which may be slow and/or highly hydrated and/or short-fibered and/or sized to any desirable degree and/or loaded with any desirable filler or coloring material and/or'containing fines. may now be laid upon the partially formed sheet whose upper surface bears the-binding material.

aaaaeae now to the drawing, Fig. 1 illustrates a machine of a well known Fourdrinier type to which myinvention has been applied. The machine includes a main head or flow box in fromwhich stock I! flows through a lip l2 upon a wire i3 of the Fourdrlnier part of a paper-making machine. The wire I3 is supported by the usual breast roll is and driven by the usual couch roll it in the direction of the arrow in Fig. 1.

I'he'stock II is flowed upon the wire in a layer of any desired depth controlled in a well known manner as by adjustment of the lip l2 and variation in the speed of the wire. The stock upon the wire is progressed by the wire over a series, comprising any desired number, of table rolls l1, the

action of which is to progressively remove water from the stock '11. The partially dehydrated stock is then 'carired over a series, comprising any desired number, ofsuction devices It which serve to further successively dehydrate the stock and form the same into a web of interielted' fibrous material. The web may then be conducted from the wire to the usual pr im. drying and calendaring stages of paper machines of well known types.

According to my invention, a second head or flow box it is supported in any convenient manner above the Fourdrinier wire it. Preferably,

- the supporting means for head box I! is as constructed as to permit the box I8 to be located at any desirable position along the wire in the I path of travel thereof. The headbox i8 is provided with th'e usual lip II from which stock 20 may be flowed in a layer of controlled depth upon the wire II.

' As shown in Fig.

vices I! encountered by the web upon the travelling wire ii. In this position, the stock "will be flowed upon the stock II when the stock H has i been dehydratd only by the action of table rolls For example, the second layer may be a rela-' tively overcooked, well beaten kraft stock. when the stock of the first layer is of extremely free flowing nature, it maybe subjected to the action. of any desirable number of table rolls and suc-; tion boxes in order that it will be well formed and will serve as an emcientfilter mat for the layer of stock-to be subsequenti laid thereon. intermediate the degree of dehydration ofthe first layer and thus enables me-to prevent the loss of the short 53 fibers or valuable sizing, filling. or coloring materials which may be contained in the second layer of stock.

Other objects and advantages of my invention.

of the following description of preferred,.but not necessarily the only, forms of my invention taken in connection with the drawing accompanying and forming a part of this specification.

In the drawing:

Fig. 1 is a somewhat diagrammatic illustration of a machineupon which my invention may be practiced} Fig. 2 is a similar view of a modified machine; and

Fig. 3 is a greatly enlarged cross-sectional view of one form of paperboard which may be ,produced according to my invention.

Similar characters of reference indicate simi- II and the first few suction devices ll.

Located immediately ahead of the second head box It I have provided a.distributing device 5 indicated "generally by the reference numeral 22.

The distributing. device 22 may take any suitable or convenient form. Thus, this device may comprise a box or chest provided witha lip. weir or will become more apparent from'a consideration slice suitable for the distribution of dilutedmate- $18.5 The lip, weir or slice may be supplied from any suitable source other than a boxer chest, if so. desired. 'For-the purpose of illustration, 1 have disclosedv a distributing device which comprises a baiiie plate 28 which extends across the wire and. which may be corrugated, ribbed or grooved to secure an even how of materialthereon. The baiiie plate 23 is supported in any convenient manner above the wire and is preferably movable, eitherwlth or independently of the head box is, along the wire. Thelower extremity of baflie plate It acts as slip from which material maybe fiowed upon the wire II. A pipe 24 lar parts throughout the several views. Referring 7c is suitably supported and extends across the wire. The pipe 24 is connected with a suitable supply of modifying material and is provided with a series of nozzles 25 which are so designed and located as to distribute material supplied under.

pressure to the pipe, upon the b'afile 23 in the form of a finely divided spray. The material be ing sprayed by nozzles 25 is indicated by the reference numeral 28; The material 26 forms an evenlydistributed film upon the baille plate 23 and flows down the plate to be evenly distributed across the wire l3.

In Fig. 2, I have shown a modification of the 1, the second head box is is positioned above the first several suction de- H9 is illustrated in a position farther down the wire. The distributing device I22 has been correspondingly moved. In the position illustrated in Fig. 2, the stock'IZO is laid upon the stock III after the stock III has been subjected to the action of the table rolls III and a relatively large number of suction devices II8. Thus, in the device illustrated in Fig. 2, the stock III will be dehydrated to a much greater degree than the stock II upon the machine shown in A suitable binding agent I26 is distributed upon the stock III by the distributing device I22 in the same manner as discussed above in connection with Fig. 1. a

Illustrative examples of the formation of certain specific types of sheet material upon the devices shown in Figs. 1 and 2 will now be given.

Considering first the machine illustrated in Fig.1 and the sheet material illustrated in Fig. 3, a stock II of any desirable characteristics or type is flowed through the lip I2 of head box III upon the wire I3. For example, the stock II may be a kraft pulp cooked and beaten to any desirable extent. .The stock II is conducted by the wire I3 over the table rolls I1 and a suitable number of suction devices I8 to cause dehydration of the stock to such an extent that the fibers upon and adjacent to the wire I3 may become set while the stock forming the upper surface of the layer remains in watery condition. The second head box I9 is so located that the lip thereof will discharge, stock 26 upon the stock II when it has reached'the exact de-' gree of dehydration desired. Thedistributingdevice 22 is positioned immediately ahead of the head box I9 and a supply of binding material,

such as animal glue, casein, latex compounds or sizing material, is supplied to the spray nozzles 25.

to the surface of the stock II will result in an increase in the amount of water in and upon the upper surface thereof. The stock II bearing the material 26 is then conducted to the lip 2| of the second head box I9. At this point, the stock is flowed upon the watery, binder loaded surface of the stock II and commingles therewith to form a firm, interfelted, fibrous bond between the two layers of stock. For the purposes of the present example, the stock 20 may be identical in all respects with the stock II. In this case, the binding material 26 merely serves to improve the bond between the interfelted fibers within the zone of union between the-stock layers II and 26. The composite web thus formed is subjected to further dehydration by any necessary number of suction devices It and is then conducted to the finishing stages of the paper machine.

The sheet material formed according to the example just discussed is shown in Fig. 3. From an inspection of this figure, it will be seen that the fibers of layer II are well arranged and formed adjacent the wire and that they become become increasingly well arranged as a result increasingly disarranged as they approach the upper portion of this layer. It will also be observed that the lowermost fibers of the layer 20 are disarranged and thoroughly interfelted with the upper fibers of the layer I I.. The fibers within the upper portion-.ofthe layer 20 may of the action of the conventional dandy rolls This material 26 is sprayed upon the baf-- fle plate 23 and distributed thereby in an even my intention to be limited.

(not'shown) and any other devices which may be used for the smoothing of the upper surface of paper according to principles too well known to require further discussion herein. It will be observed that the binding material 26 is confined within the zone of interfelting between the may vary relative to one another to any. de-

sirable extent. Thus, either of the layers may be cooked and/or beaten to a greater extent thanthe other or the relative degrees of hydration of these stocks may be chosen as desired. The stocks II and'20'may vary in their relative freeness or fiber lengths and may contain relatively different percentages of fines, sizing, filling, coloring or other materials. Any desired characteristics or combination of characteris-.

tics may be imparted to either of the layers II or 20 and in any case the stock modifying or binding material 26 will serve toimprove the bonding or interfelting between the respective layers.

It will be understood that the exact position of the second head box I9 along the wire I3 will be chosen with regard to the type of stock furnished from the head box II and the exact degree of dehydration and fiber formation desired within the layer I I upon its arrival at the lip 2| of the second head box. It will be further understood that the exact location of the second head box I9 must be determined by experiment and that the position illustrated in Fig. 1 is merely an example to which -it is not In Fig. 2, I have illustrated a specific modification of my invention 'which is particularly adapted for the formation of a composite web whose surfaces vary widely in characteristics. The formation of a web to which this form of my invention is particularly adapted will,now be described. A stock III] which may be an undercooked kraft stock or a free flowing stock-con;- taining a large percentage of long slightly hydrated fibers may be flowed upon the'wire II3.

' The stock is progressed by the wire over the table rolls III and a sufficient number of suction tying or binding material, such as animal glue,

casein, sodium. silicate or latex compound, is applied by the distributing device I22 to the upper surface of the layer I immediately prior to the flowing of the stock I26 thereon. The

binding material I26 will remain within the zone of union betweenthe layers III and I 26 and will serve to eflectlvely improve the bond therebe' tween.

It will be understood that many modifications oi the example just given will occur to those skilled in the art. The fact that the first layer of stock III is completely formed or matted at the time the second layer is flowed thereon enables it to serve as an efiectlve filter met for any type of stock i20 which it may be desired to apply thereon. In this embodiment of my invention,1 em enabled to secure a thoroughly satisractory bond between superimposed layers of stock which difler so greatly that it has heretofore been impossible to satisiactorlly unite them by known processes.

While in the ebove examples 1 have dwelt upon the function or the stock modifying meterlel applied by the distributing device to improve the bond between separately leid plies, it will be appreciated that such materiel may nerve varlous functions. For example, a suitable quantity of sizing or filling material msy be flowed upon the partially dehydrated first lsyer to eiiect the sizing or filling of this layer upon the. wire. A second layer of unsized or unfilled or difierently sized or filled stock may then be applied by the second head box, As another example the stock modifying material may be so chosen as to at- Zii feet the inner fibers o! a composite web to stiffen or to raise the Mullen test of such a web with-- out affecting the exterior fibers and surfaces thereof.

escapee It will thus be seen that I have providedan apparatus, method andproduct fulfilling the objects o! my invention. While the above detailed description has been made in order to comply with statutory requirements, it will be unders that this description is to be taken in an illustrative rather than in a. limiting sense and that the scone of my invention is to be limited only by the onpended claim.

ll claim:

The process of forming a homogeneously interielted web oi cellulosic fibrous material, comprising flowing; 2. layer of cellulosic fibrous stock noon the wire of a Fourdrlnier type of paper making machine, dehydrating said layer to an extent suiileient to impart a substantially permanent set to ell the fibers of said layer while leaving the upper surface of saidleyer in a watery condition, flowing a quantity or thin aqueous oldheeive solution upon the watery surface of said lever and thereby increasing the amount of wer ter on the upper surface thereoi, immediately flowing anedditional layer of cellulosic fibrous stool: upon the water and adhesive loaded surface of said layer, dehydrating said superimposed layers simultaneously by suction and simultaneously thereby commingling and interlocking the fibers and adhesive in the adjacent surfaces or said layers only, and finishing said web.

GUNNAR W. E. NICHOLSON.

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