US2289686A

US2289686A - Paper manufacture

Info

Publication number: US2289686A
Authority: US
Inventors: Brainard E Socy
Original assignee: GARDNER RICHARDSON CO
Current assignee: GARDNER RICHARDSON CO; GARDNER-RICHARDSON Co
Priority date: 1939-07-07
Filing date: 1939-07-07
Publication date: 1942-07-14
Anticipated expiration: 1959-07-14

Description

2 Sheets-Sheet l B. E. SOOY PAPERMANUFACTURE Filed July 7, 1939 IIIIIIIIIIIILI l'lllll ||||||||i n ||||||||1 un Nm I All III! OblObb t July 14, 1942;

July 14, 1942t 'B. E. sooY PAPER MANUFACTURE Filed July 7, 1959 2 Sheets-Sheet? y gmmm #yy-M9 Patented July 14, 1942 ff-1T' STTES ATENTA azsassc Parra mancuernas Brainerd E Sooy, Middletown, Ohio, assigner to The Gardner-Richardson Company, Middle-- town, Ohio, a corporation of Ohio Application .my 7, 193e, sei-1n No. esatto y 1c claims.

This invention relates to paper making and more particularly to the provision of a surface coating on a web of paper material.

A principal object of the invention is vto provide a paper web having a greaseproof surface coating applied thereon under controlledconditions as a homogeneous ilm having substantiallyuniform 'and predetermined density across the entire width and along the entire length 'of 'the paper web. 1

A further object is to provide a process for applying to a paper web a coating of surfacing material having a volatile constituent such as a volatile solvent adapted to be lost by evaporation and to obtain controlled retention of such volatile constituent during the coating operation to provide `for maintaining predetermined viscosity characteristics in the coating composition and in the use of the coating composition.

A still further object is the provision of relativelysimple and inexpensive apparatus for mg' controlled viscosity and volatile content. The invention is of particular importance in the case of a coating material having a volatile solvent as one of itsconstituents, such, for example, as in the caseof a nitrocellulose coating where itis customary to make use of a mixture of highly volatile solvents such as acetone, methanol, gasoline and/or toluol." With such coating matel -rials it hasbeen found that if the coating material is merely applied to the paper web by means of nip rolls dipping into a relatively large: exposed pool of such material, the composition tends to lose a substantial .portion of the volatile solvent by evaporation. Under these conditions the composition becomes more and more vscouswith the vlpassing of time and a heavier coating film is applied. Furthermoraif the relatively thin film or coatingv material which is picked up on the surface of the pick-up roll dipping within the pool' is exposed to contact'with'the, atmosphere between the time that it leaves the pool and the' time that it is applied to the paper web a further evaporation of the volatile solvent occurswith avcorresponding change in the viscosity of the nlm. These changes in the viscosity of the coating material due tothe loss of the volatile applying such uniform thin illm of surface coating vmaterial to a web of paper.

Gtherl objects and advantages will be apparent from the following description, the appended claims and the accompanying drawings in which:

Fig. 1 is a diagrammatic elevational View illustrating the general layout of the apparatus employed inthe present invention;

Fig. 2 is a plan view with the upper press roll removed oi acoating machine constructed in accordance with the present invention;

Fig. 3 is an end elevational view taken interiorly of the end frame of the coating machine as indicated by the line 3-3 of Fig. 2;

Fig. 4 is a sectional view taken on the line 4-4 i of Fig. 2;' A

Fig. 5 is a fragmentary detail view of a portion of the doctor blades at the forward side lofthe machine; and l Fig. 6 is a. fragmentary elevational view taken at one end of the machine and showing the adjustable doctor blade at the rear of the machine in detail.

The present invention provides for -maintaining continuous controi over the characteristics `of the coating composition as regards solvent con-v tent, vlscosity and the like, to effect its application to the paper web ,in a uniform thin film havsolvent therefrom not only result in a substantial decrease in the amount of coverage which can loe` obtained witha given quantity of the material, but also result in the 'application of the coating material to the paper web in a non-uniform Illm having a density which is variable across the width of the web and which is subject to change along the length thereof.

In accordance with the present invention only so much of the coating material is supplied to the coatingapparatus which applies it to the paper .f

web'as will be used up in a relatively short period of time andthe conditions under which the coating material is applied to the web are -so controlled as to substantially avoid freecontact of the material with atmospheric air from the time that the material is introduced into the coating Aapparatus untii after it has been applied to the paper web. A fresh quantity of the coating maf terialis supplied to the apparatus only when the material already therein has been substantially used up and this fresh supply is introduced ill such manner as to cause the material which. remains in the bottom of the apparatus to be flushed or washed into a position where it will be lpicked up and applied to the web of'paper. InA

this manner the use of dominant pools which tend to retain a portionof the coating material is avoided and a fresh coating material having a predetermined constant volatile content and visstantially free from contact with the atmosphere of coating material rel until after it has been applied to the paper web y any 'substantial loss of the avoided and the coating is applied to the paper web in alm of satisfactory uniformity both transversely and lengthwise ofthe web. This uniformity of coating makes it possible to secure a marked economy in the ,use of the coating composition, since it is not necessary to apply 'an excess to parts of the web in order to secure suiicient depth of film over the entire web.

Referring now to the drawings which illustrate a preferred embodiment of the invention, and more particularly to Figs. 2 to 4, the coating machine designated generally by the reference character I is shown as comprising a pair of vertically arranged press rolls II and I2 mounted on suitable shafts rotatably supported in end frames I3 and I4. Only the shaft I5 for the lower press rolly I2 is shown in the drawings. A paper web I1 from any suitable source is fed to the press rolls in the direction of the arrow in Fig. 4 and the coating of surfacing material is applied to the under side of the web as it passes through the nip of the rolls. The bearings for the upper roll II are preferably adjustable in the end frames I3 and I4 to provide for receiving different thicknesses of paper material between the rolls, and suitable means such as adjustable springs or the like may be provided for effecting a desired pressure between the two rolls. A suitable drive means (not shown) is also provided for effecting rotation of the press' rolls in. the direction indicated by the arrows in Fig. 4.

A fountain or tank member 20 adapted to receive e, predetermined limited quantity of the surfacing material therein is supported between the frame members I3 and I4 as indicated at 2I and provides for continuously supplying the coating material to the surface of the lower press roll I2. As best shown in Fig. 4 the fountain 20 l comprises an arcuately curved front side wall YY25, an arcuately curved rear side wall 26 and an arcuately curved bottom wall `21 'I'he

curved wall portions

25, 26 and 21 are arranged concentrically with the axis of the lower press roll I2 and are positioned relatively close to the periphery of the lower roll to provide only a predetermined limited space between the inside of the fountain and the outer surface of the press roll. To provide an even more limited space between the press roll and the bottom of the fountain where the coating material'is picked up the bottom wall vportion 21 has a smaller radius of curvature than the

side wall portions

25 and 26 to position the bottom wal1 portion Icloser to the pressroll as is clearlyvshown in Fig. 4.

Suitable spacing members

28 and 29 are provided between the bottom wall portion 21 and the respective side wall portions 25 andf26 and aredwelded or otherwise imperviouslyattached to the respective portions of the wall.

The front wall portion 25 adjacent its'upper end is bent outwardly and upwardly to -provide an upwardly inclined .ledge 32 and an opstanding portion 33. A door 34 having transparent windows 35 and handles 36extends across the entire length of the fountain and is hingedly atvolatile solvent' is tached to the upstanding portion 33 of the front wall 25 as is indicated at 31. Handles 36 and hinges 31 provide for readily swinging the door 34 outwardly to provide ready access to the nip of the-.rolls for the feeding of a new web of paper thereto or other purpose. Suitable stops provided on the end plates of Vthe fountain-limit movement of the door 35 towards the press rolls to substantially the position shown. in Fig. 4. The door extends upwardly to above a'horizontal plane passing through the nip of the press rolls and is provided at its upper end with a horizontally projecting flap 38 which extends into close juxtaposition to the upper press roll II. The flap 38 is attached to door 34 by means of spring hinges 39 which normally maintain the flap in a substantially horizontal position as shown but permit the flap to swing downwardly in the event4 of some obstruction on the roll or paper web striking the same. The paper web I1 is fed to the nip of the press rolls through the relatively small spacing provided between the end of the flap 38 and the upper roll II. The door .34 and flap 38 thus substantially enclose the interior of the fountain and the nip of the press rolls at the forward sid.. of the machine and and thereby avoid substantial contact of the coating material, either in the fountain or when on the surface of pick-up roll I2, with the atmosphere at this side of the machine. L

A back cover member 42 having a radius of curvature similar to the rear wall portion 26 of the fountain is hingedly mounted on the wall portion 26 as indicated at 43 and is provided at its upper end with an inwardly projecting flange 44 which extends into close'proximity to the periphery of the lower press roll I2. Handles 45 provide for swinging the back cover member 42 to an open position' when it is desired to have access to the lower press roll, and suitable stops provided on the end plates of the fountain limit movement of the cover 42 and flange 44 towards the lower roll when the cover is in closedposition. The door 34 and flap 38 at the forward side of the machine and the back cover 42 and flange 44 at the rear side of the machine thus provide for substantially enclosing the interior of the fountain and the entire surface of the lower roll I2 to thereby avoid substantial contact. of the coating material with the atmosphere until after such material has been applied to the paper web at the nip of the press rolls and has passed outwardly from the machine.

. The fountain 20 is closed vat each end by means of a lower end plate 48 and an upper removable end plate 49. The lower end plate 48 is substantially semi-circular in shape and'is permanently attached to the side and

bottom wall portions

25, 26 and 21 of the fountain. The upper removable end plate 49 rests upon the top of the lower plate 48 and has a shape generally corresponding to the contour of the upper portion of the fountain. As shown in Figs. 2 and 3 the end plates 48 and 49 are provided with cooperating notched flanges 50 and 5I at their line of junction, and toggle screws 52 pivotally mounted on the upper end plate and having nuts 53 adapted to engage the lower flanges 50 are received within the notches 54 of the flanges and `provide for removably clamping the upper end plate 49 to the lower fixed end plate 48. The upper removable end plate 49 is so constructed as to have a tight flt with the ends of the main body portions of the fountain, and the end walls of the fountain are positioned relatively close to the ends of. the

press rolls to thus substantially prevent the leakage of air into the interior `of the fountain and escape of. the volatile solventstherefrom.: l The inclined `ledge 32 on vthe front .wall por tion of the fountain provides a support for `the doctor blades which are provided at the forward side of the machine to control the quantity of coating materialitransferred tothev paper `web at the nip of the press rolls. As shownin` Figs. 3, 4 and 5 thedoctor at this side. of the machine comprisesa plurality'of adjustable doctorblades 60 which are mounted in predetermined spaced positions along the length ofthe press roll I2 and a plurality of fixed doctor blades SI- which extend along the length of roll 'I2` betweenthe adjustable deeter blades so. The axed doctor bladestl are rigidly yattached to the ledge 32 by I ineansof screws 62 (Fig. 3) which extend through elongated slots 63 provided in the doctor blades ,a relatively large number of tapped openings 19 and if a greater adjustment of the doctor blade is required the thumb screw 11 can be entirely removed from one set of openings 'and threaded into a different set. It has been found in practice that satisfactory operation is obtained when the doctor blades 15 are adjusted to a positioning in which they are spaced approximately onefourthof ank Ainch-from the side edges of the paper web. The doctors extend forwardly of the channel support and the flange M' intoengagement `with the upper roll Il and in-overhanging relation with respect to the lower roll I2. Thus as the rolls rotate any of `the .coating `material which may have been transferred to the surface' offthe upper rollzis scraped .olf by the doctor blades and falls upon the lower rollwhere it is carried back into the apparatus for further application to thepaper web.

extend vforwardly into contact with the lowerpress lroll I2 and provide for scraping substan- As mentioned above only a predetermined limited :quantity of coating material such `as willbe used up within a relatively short period of Itime is supplied to the machine at any one time.

20 through a pair of nipples 82 whichare mounted in the rear wall portion pf the fountain addoctor blades and the press roll; after.v which the,

holdingscrews 62 are tightened and the blades e are maintained fixed inthis positioning.

The adjustable vdoctor blades-60 are adapted t be movedtowards and away from the lower press roll I2 to provide for controllinguthe'quantity of.

coating material that is carried upwardly by the surface of the roll tobe applied to the paper web" and forlimiting it to a plurality of spaced bands which distribute into a' continuous pool extending.

across the entire -nip of the rolls. As shown in.

. -vwhich extends fromthe. pump to the coating ap i jacent each endof the coatingrmachine and connect with a supply source positioned'externally of the machine.

drawing the coating material from the tank. The i pipe 81 connects with the suction side of a pump I0 driven by an electric motor 89 and the discharge side of the pump is connected to a pipe 90 paratus I0 and is provided with branch pipes SI and which connect with the nipples 82 mount-l ed in the wall of the fountain of the coating machine. The supply system as thus providedv isV entirely closed to the atmosphere and suitable slide block within the opening to4 effect the desired adjustment of the end of the doctor blade relative to the outer surface of the roll II. A collar 10 and setscrew 1I cooperate'swith the knurled head 12 of the thumb screw and the flange 69 to maintain the thumb screw in fixed axial positioning with respect to the ledge 32.

' To provide a machine that is adapted to re-` ceive paper webs of different widths the pressl means such as a checkvalve in the pump is provided for maintaining the pipe so nued with eeatjing material at all times. I'he coating material is thus introduced into the coating apparatus without the loss of any of its volatile content.

4 A means is provided for automatically startrolls II and I2 are made of considerable length.

Vand an Vadjustable doctor blade 15 is provided adjacent each end of the machine for scraping the coating material from the portions of the upper roll I I which extend beyond the edge of the paper web. As shown in Figs. 2, 4 and 6 an inverted channel member 16 is welded to theoverhanging flange '44 of the rear covermember 42 adjacent each end of the machine and the doctor blades 15 are mounted on this channel member by means of thumb screws 11 which extends through y elongated slots, 18 provided in the doctorblade and thread into tapped openings 19 providedin the top of the channel member. ,The elongated slots 1B extend substantially parallel with the laxes of the feed rolls and provide for limited ing the pump 88 to effect the introduction of a fresh supply of the coating material into the fountain 20 of the coating apparatus and for automatically terminating the operation of the pump when the predetermined' limited quantity of coating material has been supplied to the fountain. Referring toFlgs. 2, 3 and 4 a float4 chamber 95 is mounted on the rear side of the rmachine and communicates with the interior of the fountain 20 through an opening 96 provided in the wall portions of the fountain. A cork float 91 is mounted` on one end of a lever arm 9'8 and is adapted to rise and fall'with the level of the f coating fluid contained within the yfountain 20. The lever 98 is pivotally mounted on the Wall *of the float chamber as' indicated at 99 and isv mercury switch |04 are connected in the control the rolls. The channel member is providedmith circuit `|05 for the motor 89 as is diagrammati cally indicated in Fig. 1 and 'provide for. effecting operation of the motor when the contacts are The, coating material is introduced into the fountain- Referring to the diagrammatic layout of.Fig.;1 'a large supply tanky 85sis posi-- tioned in a desired safe location under the ground f closed and for. terminating the motor operation when the contacts are open.

dropped to substantially the lowermost portion of the press roll |2 the pawl will have engaged the mercury switch |04 and tilted it to an angle sufficient to close the switch contacts. 'I'he electric motor 89 and pump 88 are thus caused to operate to effect the supplying of a fresh quantity of the coating material to the fountain 20. As the level of the coating material in the fountain rises the float 91 rises with it and when the desired predetermined limited quantity of the materialhas been introduced into the fountain the pawl |02 engages the mercury switch |04 and tilts the switch to effect the opening of its contacts. pump 88 is thus terminated and no further uid is supplied to the fountain until the pawl |03 againrengages the switch to effect a closing of its contacts. By adjusting the positioning ofthe s The operation of the motor 89 andy means the time during which any of the coating materialmight come into contact with atmospheric air, such as air which might leak around the edges of the inwardly extending iiaps 38 and M, is limited to a time in which there will be substantially no evaporation of the volatiles from the coating material. In practice satisfactory results with a lacquer coating have been obupper pawl v|02 relative to the mercury switch |00 thev quantity of coating material which'is supplied to the fountain during the operation of the pump may be readily controlled. As shown the bottom wall |00 of the float chamber preferably slopes Adownwardly toward the application roll so as to facilitate complete drainage of the coating material from the chamber during each cycle of operation and avoiding its collection in pockets.

An apparatus is thus provided which maintains continuous control over the volatile content-and the viscosity 'of the coating material from the time that itis received within the large supply tank 85 until after it has been applied to the paper web by the coating machine.

- Thus a quantity of the coating material having-a predetermined volatile content and viscosity is pumped from the supply tank and introduced into the fountain tank 20 of the coating machine. The front and rear cover members 34 and I2 maintain the fountain substantially closedto atmospheric air and thus provide for maintaining the coating material substantially free from contact with the atmospheric air. The front cover member 34, furthermore, extends upwardly above the plane of the nip of the rolls and thus maintains the coating material substantially free from contact with atmospheric air during the time that it is being fed upwardly on the surface of the lower roll I2 and is being applied to the paper web at the nip of thepress rolls. An equilibrium condition is thus established Within the interior of the fountain and evaporation of the volatiles is substantially avoided until after the coating material has been applied to the paper web. A surface coating of highly uniform characteristics is thus appliedto the web under Y mined quantity previously supplied has been ap- -plied to the paper web. By thus controlling the quantity of coating-material introduced into the tained where the supply mechanism is adjusted to introduce only. such quantity of the coating material as will be applied to the paper web in a period of from six to eight minutes. i

At the e`nd of each supply cycle a small body of the coating material will remain in the bottom of the fountain. The quantity of the coating material which remains constitutes only a relatively'small proportion, about one-fourth, of the quantity of coating material which the fountain contains following each period of supply, since the bottom of the fountain is of arcuate shape and is positioned relatively close to the outer surface of-the press roll. Upon the introduction of a fresh quantity of the coating material at the rear of the machine adjacent each 'end thereof and above the level of the ,coating material remaining in the fountain, this body-of remaining material is washed from the bottom of 'the fountain into a position where it will be picked up by the roll |2 andbe applied to the paper web, the rotary motion of the roll I2 as- Sistine in this action of thevfresmy ,introduced material. 'I'he accumulation of a quantity'of old coating material in a ,dominant pool'at the bot- 1tom of the fountain is thus avoided andonly relatively fresh material is contained in the fountain at all times. At the end of a coating operation the remaining fluid is drained from the coating machine by means of a nipple |01 posionly as much of the coating material is carried to the nip of the rolls as is being used out ofthe nip, thus assuring that the coating material will not accumulate in the nip of the press rolls and that only fresh material will be applied to the paper web. A complete control over the viscosity ofthe coating material is thus maintained and the coatingmaterial having a predetermined constant viscosity spreads out uniformly across the /entire width of the paper web at the nip of the fvrolls and is applied as a film of constant uniform density on the web.

As mentioned above a marked economy in the use of the coating material is also afforded by the present invention. 'I'hus by controlling the viscosity of the coating material to effect the .application of a material having predetermined controlled viscosity at the nip of the press rolls and throughout the applying operation a substantial-increase in the amount of coverage that can be obtained with a given quantity of the coating material is effected andwith such controlled viscosity a predetermined desired coverage y canbe obtained by controlling the pressure that is exerted on the Aweb by the press rolls. For example using only the weight of the top press roll which gave a pressure of approximately 25 pounds per lineal inch of nip, coverages up to v2960 square feet per gallon oflacquer were secured, and when loaded by additional weights to fountain during each operation of the supply a pre'ssure of 60 pounds per inch, an increase in covering power up to 3925 square feet Vwas obtained. 1i-product having a uniformhomogene ous surfacing of the desired thickness both transversely and lengthwise of the webis thus provided, it being possible lto secure commercially such uniform application of the coating material with coverages ashigh as 350d-4000 square feet per gallon ofthe coating material while still p roviding a surface coating of adequatel strength and greaseproof characteristics. i

`While the process, apparatus and product herein described constitute preferred embodiments kof the invention, it is to be understood that the invention is not limitedto this precise process, apparatus andproduct, andthat changes may .be made therein without departing from the 'l scope of the invention which is defined in the 'appended claims. Y

what is claimed is:

y 1; An apparatus of the applying a surface coating material having a volratile constituent to a web of paper material comprising afountain for receiving a quantity of thin iilm on the surface of said paper web, `means for controlling the evaporation of said volatile constituent to thereby provide for applying a -surface coating substantially uniformctransversely kand lengthwmelof rthe paper webv including supplymeans for introducing said 'coating mate'- rial into said fountain, and means for controlling the operation of said supply means tol effect the introduction of only such quantity 'of the coating material as will be applied to said paper web within a predetermined limited period of time.

2. An apparatus of the character described for applying a surface coating material having a volatile constituent to a web of paper material comprising a container* for receiving a lquantity of -said coating material; means forv continuously feeding coating material from said container to-- ward said paper web and for applying said coating material as a thin film on the surface of said paper web, means for controlling the evaporation of said volatile constituent to thereby provide for applying a uniform surface coating including supply means for intermittently intron ducing said coating material into said container,

character described for viscosityincluding means for maintaining said y coating material substantially free fromcontact with atmospheric air while in said fountain and during said feeding and applying operations, and means for supplying predetermined controlled quantities of said coating material vto said fountain, on the downwardly moving side ofV said roll and above the'level of the coating material in said fountain to flush out and progressively utilize the material remaining therein., r v

4. An vapparatus of the character described for applyinga surface coating material having a volatileuconstituent to a we bof paperfmaterial comprising a containerYfor-receiving a quantity offsaidj coating material;A means lfor Icontinuously feeding coating 'material from said container tosaid coating materiahrnea'ns for continuously feeding coating material from said fountain toward said paper web and forapplying said coating material under predetermined pressure as a `intosaid container in such' o I y any remaining quantity of the coating'mateial A.wardsfsaid paper web and for applying said coatf `ing material 'asajthin film onjthesurface of said j kpaper web, meansfor controllifn'gthe evaporation 2o..

of said volatile constituent to jthereby provide for applying a uniform surface coating under conditions of predetermined viscosity including means for maintaining saidf coating material substantially free from contact with atmospheric" air while in said containrandduring said fe yng and 'applying operations, supplyme'ans'f 1nytemittently introducing said .coatingmaterial 'from thebottom of saidcontainer and'to provide' for its application to-saidpaper web, and

' means forl controlling the operation fof saidsupply means to effect the introduction o'f'eniy 'such quantity of thercoating material as will be applied to said paper 'web within a predetennined limited period of time during each operation of the VSupply means and to effect subsequent operationjof said supply means only'after ysubstantially all of said` predetermined quantity of the coating material has been -applied to said web.

5. An apparatus of the characterldescribed for applying a surface coating materialfhaving a volatile constituent to a web of paper `material comprising a roller for applying said coating material to said paper web, a fountain tank for receiving a quantity'of said coating material and applying the sa'me to the outer surface of said -roller, said fountain tank' having a lower arcuate wall spaced relatively close to the peripheral surand means for controlling the operation of said f supply means vto effect the introduction of only a predetermined limited quantity of the coating material into said container during each operation of the supply means and to eect a subsequent operation of said supply means only after ing material as a thin film onl the surface of said paper web, means, for controlling the evaporation of said volatile constituent to thereby provide for applying a uniform surface coating under conditions of predetermined controlled face ofsaid roller, means for supplying fresh coating material to said fountain tank to displace that remaining therein and to' cause progressive feeding of substantially the entire quantity thereof into contact with the surface of said roller and means including a pair of cover members mounted on the upper portions of said fountain vtank `and extending in overhanging relation with respect to said roller for substantially closing the interior of said tank from contact with atmospheric air to thereby avoid substantial evaporation of said volatile constituent of the coating material and provide for the uniform application of a coating to said web of paper.

6. An apparatus of the character described for applying a surface coating material having a volatile constituent to `a web of paper material comprising a roller for -applying said coating material to said paper web, a fountain tank for receiving a quantity of said coating material and applying the same yto the outer surface of said roll, means including a plurality of spaced-apart doctor blades arranged to engage thesurface of said roller and a plurality of adjustable doctor blades positioned intermediate said spaced blades and mounted for adjustment towards and away paper' web, and means including a pair of cover members mounted on the upper portions of said lation with'respect to said roller for substantially closing the interior of said tank from contact with atmospheric air to thereby avoid substantial evaporation of said volatile constituent of the coating material.

'7. An apparatus of the character described for applying a surface coating material having a volatile constituent. to aweb `of paper material comprising a roller for applying said coating ma.-

" terial to said paper web, a fountain tank for receiving a quantity of said coating material and applying the same to the outer surface of said roll, said fountain tank having a curved bottom wall arrangedysubstantially concentric with the axis of said roll and positioned relatively close to the. periphery o f the roll, a oat chamber communicating with said fountain Atank at the bottom portion thereof, means including a float received within said float chamber for controlling the introduction of said coating material into 1 tain from contact with atmospheric air to thereby avoid substantial evaporation of said volatile constituent of the coating material.

8. An apparatus of the character described for applying a surface coating material' having a A volatile constituent to a web of paper material comprising a roller for applying said coating material to said paper web, a fountain tank for receiving a quantity of said coating material and applying the same to the outer surface of said roll, said fountain tank having a curved bottom wall arranged substantially concentric with the axis of said roll and positioned relatively close to the periphery of the roll, means including a pair of inlets arranged in the rear wall of said fountain tank adjacent the ends of said roll and positioned above the level of the llovvermost portion lof the roller for introducing fresh quantities of said coating material into the interior of said fountain tank, and means including a pair of cover members mounted on the upper portion of said fountain tank and extending in overhang- 'ing relation With respect-to said roll for substantially closing the interior of said fountain from contact with atmospheric air to thereby avoid substantial evaporation of said volatile constituent of the coating material. y

9. An apparatus of the character described for applying a surface coating material having a volatile constituent to a web of paper material comprising a pair of rollers adapted to receive said web of paper material within the nip thereof, a fountain for receiving said coating material and applying the same to the surface o f one of said rollers, doctor means for controlling the quantity of coating material carried by said introduction of coating material into said fountain to provide for supplying only predetermined limited quantities of the coating material therein and for maintaining substantially all of the coati fountain tank and extending in overhanging re- 5 ing material within the fountain in a relatively fresh condition having a substantially constant volatile content. v.

10. An apparatus of the character described for applying a surface coating material having a volatile constituent to a web of paper material comprising a pair of vertically arranged press rolls adapted to receive said paper web within the nip thereof, a fountain tank for receiving a quantity of said coating material and -applying the same to the outer surface of the lower press roll, said fountain tank having a curved bottom portion arranged substantially concentric with the axis of said lower roll and positioned relatively close to the periphery of the roll, doctor means carried by said tank adjacent the forward side of said apparatus for controlling the quantity of coating material carried by said lower roll to 4said, paper web, means including a pair of cover members mounted on said fountain tank at the front and rear sides of said apparatus and extending in overhanging relation with respect to said lower rollerfor substantially closing the interior of said fountain from contact with atmospheric air, said front cover member extending upwardly beyond a horizontal plane passing through the nip of said press rolls and to a position closelyadjacent the periphery of the upper roll to thereby substantially close said nip at the forward side of the apparatus from contact with atmospheric air, and doctor means adjustable longitudinally of said press rolls adjacent each end thereof and extending in overhanging relation'with respect to the lower press roll at the lrear side. of said apparatus for scraping coating material from portions of said upper roll which extend outwardly beyond the side edges of said paper web.

11. In a process of the character described for applying a surface coating material having a volatile constituent to a web of paper material, the steps which comprise intermittently introducing said surface coating material into a feeding zone, continuously feedingthe coating material from said feeding zone toward said paper weband applying the coating material as a thin film to the surface of the paper web, maintaining the coating material substantially free from contact with atmospheric airwhile in said feeding zone and during said 'feeding and applying operations to thereby avoid substantial evaporation of said volatile constituent and provide for applying a uniform surface coating, controllingthe supplying of the coating material into said feeding zone to introduce only such predetermined quantity of the coating material as will beapplied to the paper web within a predetermined limited period of time, and effecting. subsequent introduction of the coating material into said feeding zone only after substantially all of said predetermined quantity of coating' material previously introduced has been applied to the paper web, and in an amount in excess of the quantity of coating material remaining in said feeding zone.

12. In' a process of the character described for applying a surface coating material having a volatile constituent to a web of paper material, the steps which comprise intermittently introducing said surface coating materialinto a feeding zone, continuously feeding the coating material from said feeding zone toward said paper l aasaese web, applying the coating material as a th' film to the surface of the paper web, maintaining the coating material substantially free from contact with atmospheric air while in said feeding zone and during said feeding and applying operations to thereby avoid substantial evaporation of said volatile' constituent and providefor applying a uniform surface coating, controlling the supplying of the coating material into said feeding zone to introduce only such predetermined quantity of the coating material as will be appliedto the paper web within a predetermined limited period of time, effecting subsequent introduction of the coating material into said feed-` ing zone only after substantially all of said predetermined quantity of coating material previouslyintroduced has been applied to the paper web, and effecting the introduction of the coating material into said feeding zone in such manner as to wash any remaining quantity of the coating .material from the bottom of said zone andto provide for its application to said paper web.

said traveling web, controlling the evaporationA of said volatile constituent and maintaining said coating material substantially free from contact with atmospheric air during the .time it is within said feeding zone and being picked up and transferred to said traveling web of paper to thereby provide for applying a uniform surface coating 13. A product of the character described comprising a web of paper material having a uniform, vhomogeneous.greaseprooi surface coating film of nitrocellulose material of predetermined substantially constant thickness and density both transversely and lengthwise of the web, said coating film being substantially impervious in a thin filmspread to provide a coverage of up to 3500 to 4000 square feet per gallon of the coating material, said productbeing further character- -lzed in the surface coating being applied to the paper web under predetermined substantially uniform controlled conditions of viscosity and volatile content.

-14. An apparatus of the character described for applying a surface coating material having a volatile constituent to a web of paper material Y comprising a fountain for receiving a quantity of said coating materiala float chamber in diing its bottom wall sloping downwardly to discharge material therein substantially completely linto said fountain, a pair of nip rolls through which the web is passed, the lower nip roll dip- .ping within said fountain and picking upa lm yof coating material on its surface to be carried.

upwardly into transferring relation with the web of paper, means for regulating the quantity of coating material carried by said roll into contact with said web, and means for controlling'the evaporation of said volatile constituent and for t maintaining said coating material substantially to the web of paper, and supplying additional quantities of coating material to said feeding zone asthe material is withdrawn therefrom in excess of the quantity remaining therein and in such manner as to flush the `remaining material toward the point where it is picked up for transfer to said web.

16. An apparatus of the character described l for applying a surface coating material having a volatile constituent to a web of paper material comprising a roll for applying said coating material to said paper web, a fountainfor receiving said coating material and applying the same to the outer surface of said roll, means for maintaining the viscosity of the coating material substantially constant within said fountain and on the surface of said applying roll 'including means substantially closing the interior of said fountain and the surface applying side of said roll to contact with atmospheric air to thereby avoid substantial evaporation pf said volatile constituent of said coating lmaterial, means for p introducing fresh supplies'of said coating materect communication with said fountain and havrial into said fountain to replace material with-y drawn therefrom by said roll, and means for controlling said lntroducing means to provide for introducing a fresh supply of said coating. material after the major quantity thereof in said fountain has-been withdrawn and in a quantity greater than the quantity of coating remaining in said fountain to thereby maintain substantially all the coating material within said fountain in a relatively fresh condition having a substantially constant volatile content.

BRAINARD E. SOOY.