US2249089A

US2249089A - Coating method and apparatus

Info

Publication number: US2249089A
Application number: US260188A
Authority: US
Inventors: John D Murray; Russ B Leech
Original assignee: Standard Process Corp
Current assignee: Standard Process Corp
Priority date: 1939-03-06
Filing date: 1939-03-06
Publication date: 1941-07-15
Anticipated expiration: 1958-07-15

Description

I y J. -D. MURRAYETAL v 2.249.089

- comma METI-IdD AND APPARATUS Filed llafch 6, 1939 3 Sheets-Sheet 1 John D MIX/d] July 1941- J. b. MURRAY ETAL 2,249,089

COATING METHOD AND APPARATfiS Fil ed llax ch 1939 3 Sheets-She'et 2 Russ B. Leech Q Patented July 1941 said Murray assign'or to-The Liquafilm Corporation, Chicago, 111,, a corporation of Illinois;

said Leech assignor, to Standard poration, Chicago, lll

\ ware Process Gora corporation of Dela- Application ma '6, 1539. Serial No. 26il,1 8 8 Claims. (Chill-33) y This invention relates to methods and apparatus for coating surfaces of sheets, webs or the like and is more particularly concerned with methods and apparatus for applying coating material upon such surfaces to obtain a uniform finish thereon.

In coating such sheet or web surfaces, the iii-- resins which are melted for application to the" sheet surface, although the invention is not so limited. V

Coating methods and apparatusin general use today for applying surface coatings of liquids and similar materials to sheets or webs have not provedsuccessful for applying smooth coats of melted plastic material to sheet or web surfaces.

These plastic materials harden almost instantly when they are deposited upon'the sheet surface and attempts to spread these coatings during and after deposit have resulted only in incomplete, non-uniform streaky and uneven coatings.

Moreover, these present day coating methods are relatively slow and afford no measured or accurate control over the amount of. coating material actually deposited on the surface.

Withthese defects of the prior art in mind, it is a major object of the present invention to provide a novel method and apparatus for speedily applying accurately measured and controlled quantities of coating material upon a sheet or web surface in a uniform'coating.

A further object of the invention is to provide a novel method and apparatus for coating a sheet surface which comprises progressively passing a sheet, upon a surface of which coating ma-' terial has been deposited, over a smooth even face, or a plurality of smooth even faces in succession, under tension or pressure and then contacting the coatedsurface with a smooth flexible straight edge, at anangle selected to give a predetermined finish to said surface. In its preferred embodiment, suitable adjustments are provided for determining the area of contact between the coated sheet or web surface and the smooth face, and for determining the angle at the straight edge. Also provision is made for ap- 1' plying heat to the coated surface while in contact with the smooth face. Preferably the straight edge is provided at the termination of a smooth even flexible face member loosely supported ad'- .jacent one end and overlying a smooth relativelyrigid backing member. Usually the sheetor web is maintained under tension during this treatment.

A furtherobject of this invention isto provide a novel method and apparatus for coating a sheet surface or the like wherein controlled quantities of coating material are deposited upon the surface, and subjected to suflicient pressure and heat, by special'smoothing apparatus, to fuse the deposited material intoa smooth, uniform coating. In the preferred embodiment, the deposited material is a melted thermo-plastic 'deposited upon the surface by a special grooved roller and the fusing temperature must be at least as high' as the temperature of the melted thermo-piastic when it was deposited.

-A further objectof the invention is to provide a novel coating material depositing roller having either a plurality of fine, closely adjacent surface grooves, or uniformly spaced pockets, of uniform predetermined depth and width.

A further object of the invention is to'provide a novel apparatus and method of coating and glossing or finishing a sheet surface with thermoplastic material wherein the sheet, upon a sur- 1 face of which the material has beendeposited, is

progressively drawn under tension over a smooth heated face with its uncoated side in contact with said face over a substantial area and then the coated surface of the sheet is passed over a smooth flexible straight edge at an angle selected to give a predetermined finish to said surface.

If desired, the coated surface of the sheet may be exposed to additional heating means such as a radiant heater as it passesover said surface and the straight edge is preferably automatically maintained at .a predetermined high temperature.

Further objects of the invention will presently appear as the description proceeds in connection with the appended claims and the annexed drawings in which:

Figure 1 is an end elevation of a coating apparatus for carrying out one embodiment'of the invention.

Figure 2 is a side elevation of the special coating depositing roller of the invention with a section of its peripheral surface greatly enlarged to illustrate the groove formation.

' coating roller 24.

- "Figure 3 is a fragmentary sectional view of a illustrating the manner in which the coating material is deposited upon the sheet surface prior to the smoothing operation.

Figure 4 is a fragmentary view of the surface of a further embodiment of the coating roller illustrating a series of surface pockets defining a grid pattern.

Figure 5 is an end elevation illustrating another embodiment of the coating and, finishing apparatus of the invention wherein the glazing blade is separate from the smoothing surface which contacts the uncoated surface of the sheet.

Figure 6 is a somewhat diagrammatic view of still a further embodiment of the coating and smoothing apparatus of the invention wherein the uncoated web surface is backed by a cylin drical roller.

Figure 7 is a somewhat diagrammatic view ilj lustrating a further embodiment of the coating and smoothing apparatus which is especially adapted for relatively high sheet or web speeds.

Figure 8 is an exploded viewin section illustrating an insulated glazing blade holder.

Figure 9 is a fragmentary sectional view of a notched bar for wiping va smooth surfaced coating roller.

Figure 10 is a fragmentary front elevation in fluid at a desired temperature. Since the invention is not concerned with the specific type of heater construction, further description of it is not necessary to understand the invention. A suitable drain plug 36 is provided at the bottom of container 29.

A door 39 of container 29 may be opened for access to the coatingroller. Suitable end walls on container 29 retain the coating liquid and are preferably in fluid tight connection with shafts 23 to prevent the fluid from escaping to the bearings in journal 22. These fluid tight connections are designed to permit the above described adjustments of the container.

Each frame portion I6 is provided with an angular projection 4| forming a slide guide 42 supporting slide blocks 43 for rotatably and adjustably supporting opposite end shafts 44 of bifurcated doctor blade support 45.

A doctor blade holder 46 is removably secured between the arms of support 45 by screws-41 or similar releasable fastening elements. Doctor blade holder 46 comprises a pair of rigid bars clamped along one end of the doctor blade. The doctor blade includes a relatively stiff blade 46 .of sheet steel or the like serving as a backing for a flexible blade 49 of spring steel, or some material section illustrating further the blade of Figure 9.

Referring to Figure 1,.a heavy base II is provided with a vertical front frame member l2 and a pair of rear corner posts I3 joinedby a horizontal apron H. A pair of horizontal frame end members l5 extend from posts H to the bottom of the intermediate vertical frame portions 3 and a top frame member I! connects front'memberl2 and intermediate frame portions l6.

Preferably base H and frame members l2-l| comprise an integral heavy casting having suflicient weight and rigidity to withstand vibration due to the driving mechanism.

Coating deposit apparatus Each frame end member I 5 is recessed at I8 having similar properties, which extends substantially parallel to the axis of cylinder 24 and,

bears in wiping engagement with its cylindrical surface along its entire length.

A handle 5|, rigidly secured to blade support 45, regulates thepressure of blade 49 upon the surface of cylinder 24. When handle 6| is pushed downwardly in Figure 1, blade support 46 is rocked counterclockwise about shaft 44 to. ease the-pressure of blade 49 on cylinder 24. Movement of handle 5| in the opposite direction increases the pressure of blade 49 on the surface of cylinder 24.

threaded bore 53 for receiving a threaded portion of a doctor blade adjustment rod 54 having a handle 55. Rod 64 is formed. with a rotatable bearing portion which extends through block 43 and terminates within a recess 66 in block 43.

Collars 61 and 66, secured to rod 54 by suitable -means such as pins '69 and 6|, abut adjacent A plate 25 is pivoted at 26 on each support i9 and liquid tight sealing shoes 21 extend from each plate 25 to shafts 23. An idling roller 26- is supported by webs 25 with its cylindrical surface I g in substantial contact with the surface of roller 24 for'a purpose to be later described.

A container 29 is adjustably pivoted on rod 3i to vary the level of the coating solution. The free side of container 29 is provided with a projecting rotatable pin 32 resting in slot 33 formed at one end of rocklever 34 fixed to pivotal shaft" Shaft 35 is rigid with a crank 36 having an elongated angularly disposed handle 31. Referring to Figure 1, rotation of handle 31 in a clock-' 'direction lowers container 29. Shaft 35 is Journaled in a suitable rigid extension from the frame edges of block 43 and recess 56. When handle 55 is rotated, rod 54 is displaced longitudinally and block 43 is thereby displaced along its guide 42.

The above described doctor blade adjustments are provided for correctly aligning the doctor blade with the cylindrical coating surface and for varying the angle and pressure of the blade at that surface.

The doctor blade is heated by any suitably controlled heating means (not shown) The web S to be .coated is led over the top of roller 24 tangentially to its cylindrical surface, being guided by idler rolls 62 and 63 iournaled in suitable bearings in frame members 64.

An impression roller 65, the cylindrical surface of which is preferably covered with a resilient blanket of rubber or some suitable material, is mounted for rotation in vertical axial alignment with the coating roller.

End shafts 66 of roller 65 are journaled in bearings 61 on slide blocks 66 and a removable cap 69 is secured upon each bearing by screws Ii. Each block 68 is slidably supported upona vertical guide 12 on frame members l6.

An integral boss 13 on each block 66 rotatably carries the lower end of impression roll adjustment rod 14. Collars l6 and I6, secured non- 18 by pins l1 and I8 respectively, prevent axial displacement of rod" with respect to boss 18 when rod I4 is rotated.

When either handwheel 86 is rotated, rods I4 are displaced vertically to shift-blocks 68 .along guides I2 and to effect vertical adjustment of the whole impression roller 66.

Coating roller Roller 24 is preferably made of steel and is accurately ground to form a true cylindrical surface 81. By means of a. special milling tool, a plurality of closely adjacent, fine line grooves 88 are cut into surface 81. parallel and are inclined sufliciently to allow the outer plane surface of the cylinder to be wiped clean by doctor b1ade48. They may be disposed at from 10 degrees to 80 degrees but preferably are disposed at about 45 degrees to the axis of the roller and are of uniform depth and shape so as to contain the same amount of coating material.

The size and spacing of the grooves is varied in accordance with the nature of the materials and the amount to be deposited per unit ofarea.

The ratios of line width to groove width are such that suiilcient area is provided on the raised surfaces or lines so no embossing of the web or sheet material from the grooves or pockets. The grooves may be arranged at any angle with the cylinder axis but should be disposed at such an angle with respect to the edge of the doctor blade that proper wiping of the plane surface of the cylinder is assured. For uniform deposit of thin coatings, it is essential that all of the grooves be of uniform depth in order that each shall deposit the same amount of material. For this reason the roller surface'is cut by a specially de-- a 2,249,089 rotatably upon rod 14 at opposite sides of boss the cylindrical surface.

when it is desired to accurately deposit a coating of given thickness upon a sheet surface, a rollerhaving its surface milled to provide grooves of suitable depth and size is selected or prepared for the job at hand.

A modified form of roller surface is illustrated at 8| in Figure-i wherein the roller surface recesses comprise uniform pockets 82, milled into the roller surface by special milling tool to produce a grating or screen eifect at .the'roller surface. In this modification the cylindrical-roller surface appears asa plane surface 88 into which pockets 82 are cut.

While the coating roller surfaces have been.

plication of Russ B. Leech Seri-allNo. 272,526, filed These grooves 88 are to be coated occurs under the pressure required to assure satisfactory drawing of the coating signed milling tool so that the exact dimensions.

per inch. Each groove is .001 inch deep, and the wall between grooves is one-third the width of the groove.

May 8, 1939, wherein this deposit roller per se an the method of making it are claimed.

Coating and finishing apparatus cured non-rotatably thereto at oppositeends of lug 88'.- An operating handle 84 isrigid with the upper end of each rod I88.

The lower end of each rod is threaded within bore 86 which is preferably integral with 'a. slidable frame member 86 mounted in slide guides 86. Frame members 86 are rigid with opposite ends of a quadrantshaped shoe 8i having a smooth curved surface 88 which is prefthreaded end of an adjustment rod I8I at whose I upper end is an enlarged rigid handle I82. Each rod IN is rotatably supported in a bore in a ledge I88 preferably integral with each member 86, and is prevented from vertical, displacement therein when rotated. v

A wide flexible glazingblade I84, preferably of thin sheet doctor blade steel, of :from .005 to .020 ofan inch thick. andwhich may .be ta-,

pered at its free end if desired, hasone edge loosely held between a pair of bars I85: and I86 by screws or bolts which pass throughholes in the blade of larger diameter to permit heat expansion. Preferably the'bars of I88, and I86 are of heat insulating material, or heat insulated. If this edge is tightly c am d,- the blade I84 will warp when the necessary heat is applied thereto and will not present a smooth straight free edge in contact with the coatlngmaterial.

While for some purposes grooves 88 may be.

formed'by acid etching, this method has been 'found unsatisfactory because the etching process does not afiord sufficiently accurate control over the depth and other dimensions of the grooves.- It will be further understood that the surface grooves on roller 24 may be formed by electro- The opposite ends of bar I86 are secured to blocks 88 so that blade I84 is coextensive with I surface 88. I

Blade I84 extends upwardly from its support at a tangent to the lower edge of surface 88 and extends over surface 88 in contacttherewith. Since blade I84 is generally too'thin" and flexible to support itself. in an upright position, it is deposition or built up in some other manner, upon effectively supported medially. by surface 96, which stops short of the free .edge of the blade. In practice a projection of one quarter of an inch of free edge of blade I94 beyond the medial support, has given excellent results. This projection gives suflicient flexibility of support to the free blade edge to maintain it in contact with the surface under treatment, regardless of variations in tension along'the surface, and regardlessof surface irregularities. This resilient flexing action of the blade in compensating for irregularities is plainly visible in operation.

Ayibration restricting roller I96, whose end shafts'l99 are supported rotatably in blocks III slidable upon frame member 96, has a continuous blanket' of rubber or other resilient material at its peripheral surface for contacting the top surface of a. sheet whose lower surface is contacted with blade I94.

Roller I96 extends along the whole length of surface 98 adjacent the free end of blade I94 and isadjustable toward and away from surface 96 along a line which is generally normal to a common tangent to surface 96 and roller I96.

Each frame member 96 is provided with a ledge I I2 for rotatably supporting an adjustment rod II3 whose lower threaded end is received .within a threaded lug II4 integral with block An adjustment rod I22 threaded in a thread-'- ed bore in each block H6 is rotatably supported in a suitable ledge. I23 integral with each frame member 96 and is prevented from axial displacement by cooperation of an enlarged operating head I24 and an enlarged portion I25 of rod I22'with opposite sides of ledge I23.

Beyond roll I2 I, an elongated, arcuate, smooth surfaced cooling member I26 is mounted upon the frame by suitable supports I21 and I26 rigid with boss I9 and frame member II respectively. The web contacting surface of member I26 is cooled by circulation of water or some other fluid. Any other suitable web surface cooling means maybe used at I26.

Beyond the cooling member I26, which is provided to set the coating sufliciently to pass through draw rollers without injury, frame members'II are provided with draw roll supports I29 supporting end shafts I3I of draw roll I32 which is driven by a suitable mechanism (not shown) in synchronism with the rewinding drive mechscrews I31 are rotated, roller I33 is vertically displaced. I

Near the upper ends of frame members I2, aligned support brackets I39 are provided with slotted guides I for receiving'end shafts I42 .of a guide roller I43. Each end'shaft I42 is rotatably connected to adjustment screws I44 cooperating with suitable threaded bores in bracket I39 for vertically adjusting roller I43.

Operation of, coating apparatus reel over guide roller I43 downwardly to the coat- I ing deposit station where it is directed along the lower surfaces of idler rollers 62 and 63. the web is drawn through the pass defined by driven coating roller 24, and impression roll 66. As described above, roller 66 may be vertically adjusted toward and away from roller 24 to vary the pressure of the rollers upon the web surfaces.

When the material to be applied to the web surface is thermo-plastic, it is placed in pan 29 and heated so as to maintain it in a fluid state. The fluid coating material in the container is maintained at such a. level that a substantial portionof the surface of roller 24 is always im mersed. The supply of coating material may be replenished manually or automatically as desired and the latter operation is made possible by' the fact that roller 24 deposits known measured quantities of coating material at a constant rate as will be described below.

As roller 24 rotates in a clockwise direction in Figure 1, surface grooves 66 become fllled with coating material as they travel through the fluid bath. Coating material on the plane roller surface is wiped away by blade 49 and falls back into pan 29. Preferably the surface of roller 24 and the wiping blade 49 are thermostatically mainupon either.

After passing doctor blade 49, the surface of roller 24 comprises a clean cylindrical surface 61 and a plurality of grooves 69 filled to the level of surface 61 with fluid coating material. The coating material is transferred to the under surface of web S at the pass deflned by rollers 24 and 66 where surface 61 contacts the bottom web surface directly. The deposited coating material assumes .the form of a plurality of uniform rows or ridges 99 lying upon the web surface as illustrated in Figure 3A.

If desired, the web surface may be pre-heated, but generally the web surface is substantially cooler than the coating material and most thermo-plastics solidify or thicken almost instantly upon contact with the web surface.

After passing the depositing station, web S passes through the smoothing station or stations with the coated web sirrface in full contact with a substantial area of blade I94. Since web S is tensed, blade I94 is forced into surface contact with the underlying heated arcuate face 99 so that the coated web surface passes over a heated, smooth, flexible arcuate face at this station.

The coating on the web is now subjected to a higher temperature than at the coating station because here the now partially solidified ridges of coating must be leveled off by heat and pressure in the very short period of time that the web passes over blade I94. This temperature varies in accordance with the nature of the coating material, and the time of contact of the material.

The area of contact between the coated web surface and the smooth face of blade I94 can be web passes thereoven,

surfaces is effected in accordance with the speed of operation desired.

Excessive vibration, under certain conditions is prevented by roller I08 which urges the free end of the blade firmly toward the upper portion of face 98, and whose resilient surfacehelps absorb the minor vibrations set up in the blade.

The smoothed coated web surface is drawn downwardly over the straight smooth edge I01 of blade I04 at an angle selected to give the desired finish to the coating. This angle varies in accordance with the amount of coating material applied and should be such that the material leaves the blade edge without turbulence. For obtaining a high glossy finish upon a web coated with the thermo-plastic known as Liquafilm. Satisfactory results are obtained with the web disposed at an angle of from ten to twenty degrees with a tangent to the blade end. Web S, after passing edge I01, passes around the-vertically adjustable roller I2I and thence upwardly along the cooling member I26 to the draw roll I32. The angle between web S-with edge I01 is determined by the. vertical position of roller I2I.

' After passing the draw roll, the coated web is straight, smooth edge comprising the free end of a flexible glazing blade I6I- ofthe same material as blade I04. Blade I5I preferably contacts the surface of the web in such a manner that the edge is free from pressure on surface 6 as the web leaves it, the pressure on surface I46 being applied slightly back of the free blade edge.

Blade I5I is supported similarly to blade J04,

havingan edge loosely held between flat bars I52 and I58, preferably heat insulated, secured together and removably retained upon glazing blade support I54 by a plurality of screws I55; Cylindrical stubs I56 at opposite ends of support. I54 7 I extend intosuitable journals in brackets I51 bolted or otherwise secured to rigid frame'plates 7 Preferably shoe I45 is rigidly supported in a suitable manner at opposite ends upon plates I58 which also support the heater pivots I49.

As above described, blade I5I is medially sup ported on surface I46 and is arranged at an acute angle to 'web S, and contacts the fluid coating material in wiping engagement so as to give it a rewound upon a suitable rewind apparatus (not shown) whose speed is automatically varied as the roll diameter'increases. Roll I32 is driven at a constant speed sufficient to keep the web under a predetermined tension as it travels through the above described smoothing and glazing apparatus. 5

When a solvent lacquer or similar material which does not have to be melted to render it fluid for coating purposes is to be deposited upon the sheet or web surface, the grooved roller deposits that lacquer'or material in a substantially even coating so that the above described heating and smoothing operation need not be performed, but the surface is drawn past the smooth flexible edge to give it the desired finish.

Modifications of Leveling and Finishing Apparatus In the apparatus of Figure 5', roller 24 deposits upon the underside of web S in the manner above described and web S then passes directly over an arcuate shoe I with its uncoated side in full faceengagement with the smooth, preferably chromium plated and polished, arcuate face I46 I48 and the amount of that heat can be con-' trolled either by varying the number of heating coils energized or the distance between reflector I48.

Preferably web S enters and leaves surface I46 substantially tangentially to reduce resistance to passage of the web. Just before web S leaves surface I46, the coated surface is engaged'by a a measured quantity of melted coating material desired The projection of blade I 5I beyond its medial support, and its angle with web S should be the same as described for blade I04 in Figure 1, for the reasons hereinbefore given.

When blade support I54 is adjusted in either direction about the axes of stubs I56 by an arrangement similar'to that described for doctor blade 49 in Figure 1, the pressure of glazing blade I5I upon the web and the angle between web S and blade I5I are varied. This adjustment is made in accordance with different thicknesses and typesof .coating material as hereinbefore set forth.

Blade I5I is provided with electrical coils or other suitable heatingmeans for thermostatically maintaining it at the proper temperature as scribed for blade I04.

Instead of using stationary heated shoes such as those at 91 and I45 the invention also contemplates the use of a rotatable heated shoe such as the roller I6I illustrated in Figure 6. Roller I6I has an accurately cylindrical, chromium plated, highly polished peripheral surface over a portion of which the web S passes after the coating material has been deposited thereupon. Roller I6I is preferably provided with a variable speed drive mechanism. (not shown) so that it can be driven in accordance with desired web speeds.

After passing roller 63 web S extends along the lower surface of a vertically adjustable roller I62 whose ends are joumaled in blocks I63 slidable in uides I64 in opposedrigid frame members I65. Suitable adjustment screws I66 threadedly engaged with a ledge I61 on each member I65 and rotatably connected to each block I69 provide for vertical displacement of roller I62. When roller I62 is displaced downwardly it strips a portion of the web oil the surface of roller I 6I to vary the amount of heat applied to the web'coatingin accordance with the nature of the coating material and the speed of the web.

The uncoated' surface of web S is wrapped in contact with heated roller I6I and the coated surface of web S is contacted bythe adjustable glazing blade I5I at substantially thesame angle as described above in connection with Figure 5.

- Similarly'the auxiliary heater unit I41 directs heat upon the coated surface of web S as it passes along the roller I6 I. Roller I6I is preferably heated by suitable internal units or the like in the same manner as roller M above described.

- The apparatus illustrated in Figure 'l is a later improved development-for high speed production.

The web 8 passes over a series of flexible smoothing and glazing blades I88, each loosely held in the manner of blade I, between heat insulated bars I89 and I88, adjustably pivotally mounted upon frame portions I". These blades are of the same material and thickness, and function the same as blades I84 and Illl hereinbefore described. The blades are supported medially and heated by the curved heated bars "I, also mounted on frame portions I10, and against which they are flexed or bent by the tension of web 8 in passing between rollers I12, and over the free flextble edges of the blades. Each bar Ill is provided with a separate automatic temperature control. A roller I'l8, mounted for horizontal adjustment in any suitable manner, is provided to control the angle at which the web leaves the free flexible edge of the upper blade I88. The frame portions I'lIll supporting bars I'll and blades I88 are also adjustably mounted to vary the area of contact between the coated web surface and the flexed 'bladepo'ftion and to vary the pressure at that area of contact.

When frame portions I'III are adjusted to the right in- Figure 7, each adjacent blade I88 is then adjusted slightly counterclockwise about its pivot to insure that its free edge is raised from contact with the surface of bar I'll. Otherwise the coated surface might contact the hot car I'II after passing the glazing blade edge and the finish of the coating would be destroyed.

Frame portions "8 are all supported upon an elongated frame member I15 pivotally connected at "8' to the stationary frame bed which. carries rollers I12, so that all of the glazing blades may be simultaneously swung to one side to thread the web, or gain access to the rollers and blades.

' After passing over roller I13, the uncoated surface of web S is drawn over one or more cooling rollers I'll whiclrset the deposited and glazed fllm so that it may pass through drawing rollers without injury.

As the coated web passes over heated blades I I88, sumcient. heat and pressure is imparted to the coating at each blade so that the solidified ridges or mounds 89 are successively softened side of the sheet, thus carrying opt the coating operation without materially changing the moisture content of the sheet,-and if desired the back of the sheet may be cooled during the smoothing and glazing operation.

Insulated blade holder An insulated blade holder which may be usedfor supporting a blade-I88 of Figure 'l is illustrated in Figure 8, wherein bars I11 and "8, provided with inner facings I19 and I8I respectively of a suitable heat resistant material, such as Bakelite, are adapted to be drawn together upon opposite sides of blade I88 by suitable screws excessively in an ordinary metal holderdue to widely different temperature levels in different areas, and the blades are loosely held at one end just as are blades I 84 and lil above described.

Modified coating device Accurately measured quantities of coating material may be, deposited from a smooth surfaced cylindrical coating roller by wiping the surfacewith'a uniformly notched wiping bar, which is preferably reciprocated slowly to avoid wearing grooves into the roller surface and leaves the coating material in spaced ridges at the point of transfer to the sheet or web surface.

Apreferred form of this apparatus is illustrated in Figures 9 and 10 where a cylindrical, smooth surfaced coating roller I81, rotating in a suitable coating bath, is engaged along its entire length by a flexible springsteel bar I88 supported by a suitable holder I89. As illustrated in Figure 10, bar I88 is generally wedge-shaped in cross section and extends through a suitably formed slot or socket in holder I88, to contact the surface of roller I81. At spaced points along bar I88, it is engaged by resilient backing assemblies, each comprising a washer I9I directly engaging the bar, a coil spring I92, a second washer I93 and an adjustable screw I98 threadedly engaging washer I93 and an end wall'of holder I89.

The wiping face of bar I88 is arcuate in section so as to'provide substantially line contact between the bar androller and is notched uniformly, with the size and spacing of the notches of the same order as the size and spacing of the grooves in the grooved coating roller above described. Between each notch I95 is a tooth I98 which bears in wiping contact with the cylindrical surface of roller I8'l as illustrated in Figure 10.

As roller I 81 rotates clockwise in its bath in Figure 10, its smooth cylindrical surface becomes covered with coating material which is removed in longitudinally spaced bands by teeth I 98 as the surface traverses the wiping blade. After passing the wiping blade, the coating'roller surface contains a series of longitudinallyspaced rows or ridge s of coating material of uniform size which are transferred to the under surface of web S at the pass defined by roller I81 and an impression roller such as-that illustrated at 85 in Figure 1. I

Holder I89 is preferably rigidly mounted'upori the frame so that teeth I98 are in proper wiping contact with the roller surface and movement of bar I88 toward the roller surface is limited by its engagement with its socket on holder I89. -Any desired number of the above described resilient backing assemblies may be provided along bar I88 and each is separately adjustable to locally vary the pressure on the bar or compensate for warping of the bar. The above described resilient mounting of the bar permits it to flex and glide over solid impurities which otherwise might destroy teeth I98 if the bar were rigid.

Uniform reciprocation of the bar I88 longitusired glaze or finish to said film.

dlnally of the roller surface may be effected by any suitable means such as those now in use for similarly reciprocating ink doctor blades on printing press inking rollers.

The fundamental aspects of the above-described process and apparatus, comprising depositing measured spaced quantities of coating material on a surface to be coated, employing a flexible smoothing face for leveling the deposited quantities, and drawing the coatedvsurface over a flexible edge at a selected glazing angle, are the sole invention of John D. Murray and are claimed broadly and specifically in his co-pending application, SerialNo. 313,135, filed January 9, 1940, to which cross-reference is hereby made.

This invention may be embodied inother'specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the

4. The apparatus defined in claim 3, together with means for varying-the areaof contact between said coated surface'and said members.

scope of the invention being indicated-by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of .the claims are therefore intended to be embraced therein.

What is claimed and desired to-be secured by United States Letters Patent is:

1.,The method of uniformly and smoothly leveling coating material over a sheet surface or the like upon which it has been deposited in ridges or mounds, which comprises the steps of drawing said coated surface successively over a plurality of spaced, stationary, smooth faces,

and then contacting said coated surface with-a straight smooth edge-at an angle selected to give a glazed finish to said surface.

v 2. Apparatus for smoothing and glazing a sheet or-like surface coated with uniform spacedquantities of thermoplastic coating material comprising a plurality of smooth, heated, flexible blades with which said surface is successively contacted under pressure to smooth said spaced quantities into an even film, the final blade terminating in a free straight flexible edge over which said surface is drawn at a selected angle to. impart ade- 3. In apparatus for evenly and smoothly level mg coating material whichhas been deposited 5. Apparatus for uniformly leveling coating material which has been deposited upon a surface of a sheet or web in ridges or mounds comprising a member having a rigid smooth face and a flexible, web surfacecontacting element .loosely supported atone edge adapted to overlie said smooth face; means for passing said web under tension in contact with a predetermined end area of said' web contacting element, and means for adjusting said member to determine the area of faces to gradually level said deposited coating,

and then contacting said coated surface with a straight smooth flexible edge on. the final face at an angle selected to give a glazed finish tosaid coated surface.

- 7. In apparatus for uniformly and smoothly leveling coating material which has -been deposited in spaced quantities upon a sheet or like surface, a guideway over which said sheet passes with said deposited coating facing outwardly;

' smoothing mechanism comprising a plurality of spaced flexible blades over which said surface is upon a sheet surface or the like, aplurality of stationary members having smooth surfaces over which the coated surface is drawn in. succession, means for imparting heat to said coated surface at each of said members in such a manner that the material on said coated surface iii-smoothed out gradually as the surface passes successively over said members, and means for subsequently contacting said coated surface with a smooth straight edge at an angle selected to gives-glared finish to said surface.

said surface between adjacent rollers.

successively drawn-under pressure, each blade being supported along one edge and having a smooth face contacting saiddeposited coating, andan arcuate backing for each'blade designed to support and control the curvature of each saidblade as it bends in response to pressure of said sheet; and a movably mounted support for said smoothing mechanism for bodily and simultaneously shifting all of said bladesinto or out of engagement with said sheet surface.

- 8. In the appa atus defined in claim 7, said guideway being supported on a stationary frame,

and said smoothing mechanism support comprising a frame member pivotally mounted on said frame. I e v e 9. Inthe apparatus defined in claim 7, said guideway comprising a plurality of spaced rollers, and said. flexible blades being spaced to engag 10. In the. apparatus defined in claim 'I, the

backing for each blade comprising a rigid non-' rotatable bar extending parallel to said blade,

and means for shifting each blade and associated bar asa unit toward or from said guideway.

RUSS B. LEECH. JOHN n. m r.