US2118212A - Process and apparatus for coating paper - Google Patents

Description

May 24, 1938.

J. D. M LAURIN PROCESS AND APPARATUS FOR COATING PAPER Filed April 24, 1953 4 Sheets-Sheet l Mar ie/Illa!!! M ATTORNEYS May 24, 1938.

PROCESS J. D. M AURIN 2,118,212

AND APPARATUS FC )R COATING PAPER Filed April 24, 1953 4 Sheets-Sheet 2 yqz INVENTOR 0 BY /MI ATTORNEYS May 24, 1938. J. D. MaCLAURIN 2,118,212

PROCESS AND APPARATUS FOR COATING PAPER 7 Filed April 24, 19-33 v Sheets Sheet 3 y d 4 m 3 34 14 J9 J6 INVENTOR H11 ATTCRNEYS 1 May 24, 1938.

J. D. MaCLAURIN PROCESS AND APPARATUS FOR COATING PAPER 4 Sheets-Sheet 4 Filed April 24, 1953 |NVENTOR- v ATTORNEYS Patented May 24, 1938 UNITED STATES PATENT OFFICE.

' James D. MacLaurin, South Orange, N. J. Application April 24, 1933, Serial No. 667,676

19 Claims.

This invention relates to an improved process for coating paper and further includes improved apparatus for carrying out the process.

In the manufacture of paper, fabrics and like 5 materials of web, sheet or board form, it is frequently desirable to apply a surface coating to the sheet in order to produce some desired surface texture, color or other property. Thus, for example, it is frequently desirable to apply to the surface of paper, sizing or filling materials, coloring matter, waterproofing substances or various combinations of these or other coatings.

Certain materials of the type described have been coated on paper to a very limited extent by spraying or otherwise applying a Water solution or suspension of the desired substance on to the surface of a moving paper web and permitting the water to evaporate. Known processes of this type are unsatisfactory in various respects. One of the most serious defects in these known processes is the lack of uniformity of the applied coating which results in stripes or streaks of color or other coating material, running longitudinally of the web. These streaks or stripes form an irregular surface on the paper which is highly objectionable in that it causes irregularities in any printing which is subsequently applied to the paper. Another difiiculty is the weakening of the paper web by the watercarrying the coating substance, which frequently results in the deformation or rupture of the web as it is propelled by the feeding mechanism. The magnitude of these problems will be readily apparent when it is considered that the addition of water to the coating fluid in an attempt to make it spread more evenly over the paper web and thereby avoid the striping or streaking effect results in moistening the paper to a point where it cannot be propelled at the rate of speed requisite to the successful commercial operation. Also, paper so moistened cannot be dried except very slowly and at high temperatures which usually results in stretching the paper out of shape and producing so called pipe marks therein.

45 It is an object of the present invention to provide an improved process for rapidly and continuously coating paper or other sheet material which process not only overcomes the above noted drawbacks of prior processes, but has many added advantages as well. A further object of the invention is the provision of improved apparatus for carrying the novel process'into effect.

More specifically, the objects of the invention include the provision of a coating process capable of u-niformlv and ra idly applying a desired coating not only to ordinary paper webs, but also to paper or other sheet material of considerably less strength and/or thickness than has heretofore been possible. Other objects are to provide a process capable of giving stronger and heavier coatings with less adhesives and less coating materials than has previously been possible.

The process of the invention is carried out by applying the coating material (which may be a coloring, sizing, waterproofing, bleaching, filling, fumig'ating, odorizing or other similar substance) to the surface of paper or other sheet material in the form of a very finely sub-divided and uniformly distributed spray. When mineral coating materials are to be applied, it is preferred to use a coating fluid in the formof an emulsion of the required coating substance in water or other liquid, rather than a mere water suspension of such substance, and this emulsion may be conveniently produced by blowing air through a mixture of water and the desired solid until the entrained air supports the solid matter and maintains it in a very fine state of sub-division. This emulsion is very dilute as compared with the coating fluids previously employed, but due to the extremely fine state of sub-division of the solids therein, the coating produced thereby with my improved method of application'is uniform over the surface under treatment.

In accordance with my process the coating fluid is passed through spray nozzles which are prefer-ably of the atomizer type and which break up the fluid, by the action of air jets or otherwise, into a very fine mist. The web of paper or other sheet material to be coated is continuously moved past the coating fluid nozzles and the nozzles are continuously turned angularly with respect to the plane of the moving surface. In addition to this angular or rotative movement of the nozzles, the process may include the simultaneous reciprocation of the nozzles transversely of the moving web surface. The process preferably includes the successive application of a plurality of comparatively thin coats of the same or different coating materials, each coat preferably being dried before the next is applied, although in some cases, successive coats may be applied without intermediate drying.

In some cases, I prefer to employ moist or saturated air in the atomizing spray nozzles which produce the coating spray. This may be conveniently accomplished by passing the air which supplies the spray nozzles through a vaporizable liquid, preferab1y of low surface tension. Alcohol is a suitable liquid for this purpose although advantageous results can also be obtained by using any of the common wetting liquids. Thus, for example, the air may be saturated with carbon tetrachloride, butanol, formaldehyde or any similar liquid. Ihave found that by using moist or saturated air to form the coating spray, the coating material smooths out to a very even surface as it is applied to the paper or other material, thus producing a coating having an even texture and one to which sharp and clear printing can be readily applied.

In one modified form of my process, I prefer to further break up or disperse the coating spray at or adjacent the point Where it comes into contact with the paper or other material to be coated, and this may be conveniently accomplished by providing air jets impinging upon the spray near.

the surface under treatment. Such jets may be conveniently obtained by providing air distributing nozzles or orificesclose to the surface to be coated and directed along the surface in the direction of travel of the web.-

The improved apparatus of my invention includes novel means for spraying the coating in cluding a rotary color cylinder or manifold extending transversely of the web to be coated and provided with a plurality of spaced nozzles. Means are provided for rotating the color cylinder and, in a preferred embodiment of the invention, for simultaneously oscillating the cylinder axially whereby an extremely uniform mist or spray is produced. My improved apparatus also includes means for carrying a continuous web of paper or other sheet material at a high speed past the spraying means in such a manner that successive coats are applied to the web and the coating may be at least partially dried between each successive coat. The conveying means are further designed to permit the economical application of coating material to either one or both surfaces of the web as may be desired in one operation.

The invention will be best understood by reference to the accompanying drawings which illustrate one form-of apparatus embodying the invention and capable of performing the improved process. In the drawings;

Fig. 1 is a diagrammatic and simplified elevation of a complete coating machine embodying the invention;

Fig. 2 is a detailed elevation, on an enlarged scale, of a portion of the machine shown in Figure 1;

Fig. 3 is an end elevation of the machine shown in Fig. 2;

Fig. 4 is an enlarged side elevation of the color cylinder driving and adjusting mechanism;

Fig. 5 is a sectional plan view of a color cylinder and its driving mechanism;

Fig. 6 is an enlarged end elevation of a colorcylinder and its driving mechanism;

Fig. 7 is a sectional view of a color cylinder'on a larger scale than the previous figures;

Fig. 8 is an end view of one of the spray nozzles shown in Fig. 7;

Fig. 9 is a sectional view, taken along the line 9-9 of Fig. 7;

Fig. 10 is a fragmentary sectional view of the spray nozzle taken along the line IIll of Fig. 8;

Fig. 11 is a sectional view, similar to Fig. '7, showing a modified form of color cylinder;

Fig. 12 is an enlarged view of one of the drying cylinders; and

Fig. 13 is a perspective view of a simplified modification of my improved spraying machine.

Referring to the drawings, and particularly to Figure 1, my coating machine is generally divided into two similar sections A and B which respectively coat opposite sides of a continuous web I2 of paper or other sheet material. Corresponding parts of the two machine sections are designated by like reference characters having distinctive exponents. Each section of the machine comprises a plurality of aligned pairs of vertical main frame members I3, IQ, I and. I6, fixed to a building foundation or other suitable base IV. Thepairs of main frame members I 3 and I 4 each carry four vertically spaced substantially horizontal rolls I8, and certain of these rolls are power driven as hereinafter described. An endless belt I9 of wire mesh or other suitable perforate material is carried on each of the two horizontally aligned pairs of rolls I8, and suction boxes 20 of known construction-are suitably supported in engagement with the inner surfaces of these belts at spaced points along their spans, as shown in Figure 1. The suction boxes 26 are disposed to apply suction to points along the upper span only of the lowest belt I9 and to both the upper and lower spans'of the remaining belts of section A of the machine, whereas in section B, the suction boxes 20' contact the lower span only of the uppermost belt I9 but contact both spans of the' remaining belts.

Each of the main frame members I5 and I6 carry four vertically spaced substantially horizontal rolls I60 (Figs. 1 and 2), at least one of these rolls being power driven by suitable means such as the shaft I66, geared to the main drive shaft 4 3. An endless blanket I6l of perforated rubber or fabric is carried on each of the two horizontally aligned sets of rolls I66, the upper and lower spans of these blankets I65 being substantially horizontally aligned with the corresponding spans of the endless belts I9 carried on the rolls It in the coating portion of the machine. Suction boxes I62, similar to the boxes 28, are suitably supported on the frames I63 in engagement with the inner surfaces of the blankets 65 at spaced points, as shown in 1.

Disposed between the two pairs of main frame members I3 and I l, are two pairs of vertical color cylinder frames 26. Each pair of frames 2i carries three vertically spaced horizontal color' cylinders C, these cylinders being disposed substantially midway between the adjacent spans of the four belts I9, and extending transversely with respect to these belts as shown in Figs. 1 and 3. Each color cylinder is provided with a plurality of spray nozzles N which apply coating material or color to the paper web I2 carried on the adjacent spans of the belts, as hereinafter more fully explained. Heater cylinders 25 are preferably provided to assist in drying the successive coats applied to the web I2 by the color cylinders C. As .shown in Figs. 1 and 12, the heater cylinders 25 may be suitably supported by the frame members I63 substantially midway between the adjacent spans of the blankets. I6I. The cylinders 25 preferably extend transversely of the blankets I6I and may comprise cylindrical sheet metal elements with slots or other openings I64 distributed along the surface thereof and The continuous web l2 of paper or other sheet material to be coated, is delivered to the machine from a roll 22 by suitable feed rolls 23, passes along the upper span of the lowermost belt l9 in the coating section of the machine, then passes on to the upper span of the lowermost blanket |6| in the drying section of the machine. leaves this blanket and passes up over the idler rolls 24 and back in contact with the lower span of the next higher blanket 6| in the drying section and the lower span of the next higher belt I9 in the coating section, and thus continues in a rising serpentine course in successive contact with the lower and upper spans of each successively higher belt l9 and blanket |6|, as indicated by the arrows in Fig. 1. In the above described progress of the web through section A of the machine, it will be noted that successive coats of material are applied by the color cylinders C to one surface of the web |2 only. If a single surface coating is desired, the ope; ation is completed when the web leaves the uppermost blanket |6| of section A. If however, it is desired to coat both surfaces of the web, the operation is continued in section B of the machine, the web |2 passing over the idler rolls 26 along the lower span of the uppermost belt l9 and blanket NH and so on through a serpentine course along the upper and lower spans of each successively lower belt l9 and blanket |6|', as indicated by the arrows in section B. The finished coated web is drawn off from the lower span of the blanket |6|' by drive rolls 21 and is reeled up on a drum 28. It will be readily apparent that in passing through section B of the machine, the surface of the web opposite that coated in section A is given successive individually dried coats of material so that the web collected on the drum 28 is coated on both surfaces.

Referring now more in detail to the construction of my improved coating machine, as disclosed in Figs. 2, 3, 4 and 5, each main frame member l3 and I4 comprises two spaced columns 30 of substantially T-section between which bearing blocks 3| for the rolls l8 are adjustably supported. In the disclosed embodiment, the lowest roll bearing blocks 3|a are fixed respectively to the frames l3 and [4, but the remaining blocks 3| are slidable vertically between the columns 30 of the frame members l3 and I4. Referring, for

example, to the frame members l4 which are shown in detail in Figs. 2 and 3, vertical adjustment of the bearing blocks 3| carried thereby is obtained by means of the pairs of vertical screw threaded shafts 35, 36 and 31 whichare rotatably carried respectively in journals 32, 33 and 34 attached to the frame members M. The shafts respectively threadedly engage the lugs 38 formed integrally with or suitably secured to the blocks 3|. It is preferred to interconnect the vertical adjusting screws which act on the blocks 3t of each roll l8, and as shown in Fig. 3, this is accomplished by means of the cross shafts 39, 49 and 4| which are respectively geared to and thus operatively connect the two threaded shafts of each pair 35, 36 and 31. The vertical adjustment of the rolls l8 may be made by turning the cross shafts 39, 46 and 4| by means of suitable hand cranks. It will be understood that the rolls l8 and I69 on the frame members l3, l5 and |6 are supported and adjusted in the same manner as that disclosed in connection with the frame members |4.

The belts l9 are continuously propelled in the direction indicated by the arrows, and driving power may be delivered thereto through any of the rolls l8. In the disclosed embodiment, the rolls l8 carried by the main frame member H are driven through a vertical shaft 42 and interengaging beveled gears 43 fixed respectively on this shaft and on the shafts of the several rolls, as best shown in Figs. 2 and 3. The vertical shaft 42 may be driven by an electric motor or any other prime mover through a main horizontal drive shaft 44 running along one side of the base of the machine.

As previously noted, the two color cylinder frames 2| are spaced between the main frames I3 and I4 and may be connected together and to the main frames by the braces 45. The frames 2| are preferably so mounted that the suction boxes 26 extend between and a short distance beyond both of these frames, whereby the web under treatment is maintained firmly in contact with the belt |9' as it passes adjacent each horizontally aligned pair of color cylinders C. The two color cylinder frames 2| are identical and accordingly, one only will be described in detail.

Each color cylinder frame 2| is formed of two spaced oppositely disposed columns 46 and 41 of T-section, and a vertical bearing plate 48 is suitably fixed to the inner face of each column, as shown in Figs. 4 and 5. Three vertically spaced similar color cylinders C are supported on each pair of frames 2| and the front and rear bearing brackets 49 and 50 of the color cylinders are respectively slidably supported between the hearing plates 48 on the front and rear frames. Each front bearing bracket 49 is provided with integral end flanges 5| overlying the inner edges of the bearing plates 48 and the removable end flanges 52 overlying the outer edges of these plates, as shown in Fig. 5. A lug 53 having a vertical threaded aperture therethrough is formed,

integrally with one of the flanges 52; for engagement with the vertical adjusting screw shaft as hereinafter described. The bearing bracket 49 carries a substantially central bearing block 54 in which the shaft 55 of a color cylinder C is journaled, the engagement between the bearing block 54 andthe shaft being such as to permit both rotative and axial sliding movement of the shaft.

The means for rotating and. reciprocating the color cylinder C is carried byjthe front bearing bracket 49. Thus the vertical drive shaft 6| (which transmits power for rotating and reciproeating all of the color cylinders on the frame 2|) is journaled in a pair of spaced bearing elements 62 and 63 fixed to the bracket 49, as best shown in Fig. 6. A cam 64 and a spiral gear 65 are fixed to the shaft 6| between the bearings 62 and 63, and a thrust bearing 66, preferably of the antifriction type, is disposed between the gear 65 and the bearing 63. The gear 65 engages a spiral gear 61 which is slidably keyed to the extension shaft 68 of the color cylinder C (Fig. 5). Movement of the gear 61 axially of the shaft 68 with respect to the gear 65 is prevented by a collar 69 fixed to the bracket 49 through the vertical shaft bearing element 62, and carrying a thrust ring 10 and bearing 1| which respectively engage the opposite faces of a flange 12 on the gear 61.

Reciprocating movement may be imparted. to the color cylinder C by the cam 64. A sliding bar 13 carries a roller cam follower 14 engaging the cam 64, and the bar 13 is pivotally connected to a lever arm 15 which in turn is connected through a shaft 16 to a lever 11 having bifurcated ends 18 which embrace the color cylinder shaft 68. The shaft I6 is carried by a bracket i9 fixed to the bearing bracket 49, and an extension 80 of the bracket I9 carries a guide ill for the sliding bar I3. A tensioned spring 89 (Fig. 6) normally maintains the roller cam follower "L d in continuous engagement with the cam 84. If for any reason it is desired to discontinue the reciprocating movement of the color cylinder C, this may be done by merely disconnecting the spring 89 and moving the cylinder to its outermost position, as shown in Fig. 6, whereupon the cam 6 3 will rotate freely without moving the cylinder.

The ends of the bifurcated arms 18 of the lever I 11 are provided with inwardly directed fingers 82 which extend between two bearing rings 83 and 84 fixed to the color cylinder shaft extension 68, as shown in Fig. 5. The ring 83 bears against a shoulder of the shaft 68 and the ring 86 is clamped in place by means of a collar 85, fixed to the shaft 68 by a set screw 86 and bearing against the outer face of the ring 84. Proper clearance between the rings 94 and 83 and the fingers 82- is maintained by the interengagement of-a shoulder 8? on the collar 85 and a removable flange 88* on the ring 84.

The rear bearing bracket 50 is similar to the bracket 49 having fixed end flanges 56 and removable end flanges 51 which embrace the edges of a the bearing plates 48, and a lug 58 having a vertical threaded aperture therethrough. A bearing block 59 is suitably fixed centrally in the bracket 50 and the rear shaft 90 of the color cylinder C is rotatably and slidably journaled in this block.

The color cylinder drive shafts Bl are preferably geared to the main drive shafts M, as shown in Fig. 2. From the description given, it will be apparent that as the shafts El rotate, the color cylinders are rotated through the gears 65 and 61 and are simultaneously reciprocated horizontally across the web I2 by the cams M.

The front and rear bearing brackets 49 and 59 of the color cylinders C are preferably vertically adjustable along the frames 2I. Thus, the lowest color cylinder is adjusted by means of a screw threaded shaft 90 passing through the threaded lug 53 on the front bearing bracket 49 (Fig. 2) and a similar screw shaft 9i passing through the lug 58 on the rear bearing bracket 50. The screw shafts 90 and 9I are carried in suitable-journals 92 fixed to the frames 2i, and'these shafts are preferably operatively connected by a cross shaft 93 geared thereto and having a squared head 9 for operation by a crank or similar tool. The other color cylinders C may be similarly adjustable by means of vertical screw shafts, similarly engaging lugs on the front and rear bearing brackets, and the shafts'95 and 96 connected by the cross shaft 91 have been shown as illustrative of such adjusting means applied to the intermediate colorcylinder C.

Referring now more particularly to the construction of the color cylinders, in the preferred embodiment of the invention, each cylinder includes two concentric ducts respectively fed with air and color from opposite ends of the cylinder. As shown in Figs. 5 and 7, the disclosed cylinder comprises an outer air tube 98 and an inner concentric color tube 99. These tubes are fixed at one end to the shaft 55 by means of a head flange I which is sealed bysuitable means to the ends of both of the tubes 98 and 99 and to a flange I M on the inner end of the shaft 55. The head flange I00 closes the end of the color tube 99 and is provided with a plurality of openings I02 communicating with the interior of the air tube 98 outside of the color tube 99. The inner end of the shaft 55 is recessed as shown at I 09 to form an air passage between the openings I02 and the axial duct H99 in'this shaft. The duct I04 communicates with a duct M5 in the extension shaft 68 which is keyed to the shaft 55. Compressed air is delivered from a suitable source to the outer end of the duct H05 in the shaft 88 through a pipe 08 joined to the shaft through a stufing box of usual construction. In this manner, the pipe I08 may remain stationary while the shaft 68 rotates. As shown, the stuffing box comprises a mass I07 of packing material compressed leetween a bushing I08, fixed within the shaft duct I05, and a gland I09threaded to the shaft 98.

The opposite end of the tubes 98 and 99 are suitably fixed directly to the flanged end of'the rear shaft 80, and as shown in Fig. 5, this shaft end seals the annular air space between the tubes. The shaft 60 has a central duct IIO communicating with the interior of the color tube 99 and a color inlet pipe III is connected in communication with the duct IIO through a stuffing box comprisingpacking material II2 compressed between a bushing H3 and a gland H4. The color inlet pipes III of the color cylinders C are preferably connected to a source of supply of color (which term includes filling, sizing, coloring, waxing, chemically treating, waterproofing or any other desired coating material) through flexible tubes or hoses II5, which permit the free reciprocating movement of the cylinders. Similarly, the air inlet pipes I06 are connected to the compressed air supply pipe I6'I through flexible hoses II-8 (Fig. 3).

As previously explained, I prefer in many cases to employ moist or saturated air to fBrm the coating spray emanating from the nozzles of the color cylinders C. This may be conveniently ac complished by passing the air supplied to the color cylinders through the desired moistening liquid. As shown in Fig. 3, a closed tank or container M3 is partially filled with the moistening liquid I14 and compressed air is delivered to a point below the surface of the liquid and preferably adjacent the bottom of the tank by means.

of a pipe I15. The moistened or saturated air, which is bubbled up through the liquid, is conducted away from the top of the tank by the supply pipe I6? to which the color cylinder air supply hoses H8 are attached. With this arrangement, the moistening liquid is vaporized by the air which bubbles therethrough, and the air entering the color cylinder and forming the coating spray is thereby moistened or saturated with vapor. The coating spray formed at the color cylinder nozzles by this moistened or saturated air spreads out very readily on the paper web under treatment, thus producing a very smooth even finish. Th e moistening liquid may comprise any readily vaporizable liquid, but I prefer to employ liquids of low surface tension for this purpose. Alcohol has been found to give very satisfactory results, but I may also use formaldehyde, any of the lighter hydrocarbons or any of the known paper-wetting liquids, such as carbon tetrachloride.

Each color cylinder C is provided with'a plurality of spray nozzles N which preferably extend radially therefrom as shown in Fig. '7. The nozzles N are disposed at points spaced axially and circumferentially of the cylinders, and may be staggered or spirally arranged as desired. In general, a sufficient number of properly spaced nozzles N is provided to insure the formation of a mist which is uniform when it comes in contact with the web surface under treatment. The nozzles are preferably of the atomizer type and act to break up the color fluid into extremely minute drops or particles.

As shown in Figs. 7, 8, 9 and 10, each nozzle N comprises a central color duct II1 threaded or otherwise suitably secured in a radial opening in the color tube 99 and extending outwardly through a. larger aligned opening H8 in the air tube 98. The outer surface ofthe color tube In is provided with a plurality of longitudinally extending grooves II9 terminating in the air space between the tubes 98 and 99 and acting to conduct air to the nozzle tip. The outer end of the duct I I1 has fixed thereto a centrally perforated color tip I20. An air duct I2I is sealed to the air tube 88 about the opening I I8, and closely engages the outer grooved surface of the color duct II1. A spray tip I22, having a tapered internal bore I23, is fixed to the outer end of the duct I2I by a removable ring I24, and encloses the color tip I20 throughout the major portion of its length. The contracted opening at the outer end of the spray tip I22 surrounds and is slightly spaced radially from the color tip I20, as shown in Fig. 8, and a diametrically extending slot or groove I25 is cut in the outer face of the spray tip I22. The slot I25 is slightly tapered inwardly and terminates at the contracted opening of the spray tip I22 at a point just below the outer end of the color tip I20, as shown in Fig. 10. As'shown in Figs. 6 and '7, the slot I25 in each nozzle N extends parallel to the axis of the color cylinder C so that the spray or mist from each nozzle N is spread out longitudinally along the color cylinder and overlaps the spray or mist .emerging from the adjacent nozzle as the cylinder rotates.

A modified form of color cylinder construction is shown in Fig. 11. In this modification, the color tube I26 and air tube I21 are disposed side by side in parallel relationship and are secured together by suitable means such as the welded joint I3I. The nozzles may be secured tothis form of color cylinder by a duct I30 surrounding the concentric color duct I29 which passes through an opening in the color tube I26. Air

from the tube I29 is conducted from the annular air space I32 between the ducts I30 and I29 by means of a curved pipe I28.

As explained above, I prefer in many cases to break up, disperse and distribute the coating ma- .terial spray by air jets which strike the spray at or adjacent the point where it comes in contact with the paper or other surface to be coated. Various means may be provided to accomplish this result and in the disclosed embodiment, I provide air pipes I68adjacent the point where the coating spray from each color cylinder comes into contact with the surface to be coated. As best shown in Figs. 2 and 3, the air pipes I68 may be mounted in horizontally aligned openings in the frame members 2I at points just preceding the color cylinders with reference to the direction of travel of the web carrying belts I9. Thus there are two air pipes I68 for each color cylinder C, one below the color cylinder C for dispersing the coating spray descending from the cylinder on to the web surface passing beneath the cylinder,

and one above the color cylinder for dispersing the coating spray rising from the cylinder to the web surface passing over the cylinder. Compressed air from a suitable source may be supplied to each air pipe I68 through a hose or other flexible duct I16 attached to one end thereof, as

shown in Fig. 3. Each pipe I60 is provided with a plurality of air orifices I69 which preferably comprise substantially aligned spaced slots running lengthwise of the pipe, as shown in. Fig. 3. The slots I69 are so provided that the air jets emerging therefrom strike the coating spray adjacent the point where it contacts with the web surface under treatment, as shown by the dotted lines in Fig. 2. These jets cause the even dis-- persion or distribution of the coating spray over the web surface with the result that the coating is very evenly applied.

The air pipes I68 may be stationary or they may be reciprocated axially by suitable means. When axial reciprocation of the air pipes is desired, the ends of the pipes, or suitable fittings attached thereto are slidably supported in openings in the frames 2|, and reciprocating movement may be imparted to the pipes through brackets connected to the adjacent reciprocating color cylinder. As shown in Figs. 2, 3 and 5, a bracket I10 is rotatably fixed adjacent each end of each color cylinder 0 between suitable collars or shoulders I1I Each bracket I10 has two outwardly extending arms I12, the ends of which are respectively clamped by suitable means to the two adjacent air pipes I68 at points adjacent their ends. With this arrangement, when each color cylinder reciprocates, it imparts reciproeating motion to the air pipes above-and below such cylinder.

The operation of my above described coating machine in carrying out the improved coating process will now be described. The coating fluid, or color as it is usually termed, is first prepared by thoroughly mixing the solid coating matter in an extremely fine state of sub-division with water or other suitable liquid. A wide variety of materials may be used in compounding the coating fluid, depending on the finish desired. Thus the fluid may be composed of water or other fluid mixed with adhesives, oils, paraffin, waxes, fillers, coloring materials, latex, lacquers, metal powders, etc. Some of the ingredients may be water solu-' ble and hence form a uniform solution in the water carriage, but substantially all coating compounds contain solids such as fillers and coloring materials which are not soluble and normally tend to settle out of ordinary water suspension. My coating fluids are very dilute, containing in some cases as little as 5% solids as compared with solutions heretofore employed which usually contain in the neighborhood of 20% solids or more. After thoroughly mixing the ingredients of the desired coating fluid, the fluid is thoroughly emulsified by blowing powerful jets of compressed air therethrough. The entrained air in the emulsion suspends or supports the solid particles and maintains them in an extremely fine state of sub-division. The resulting emulsion carries the solids in finely divided and. uniformly dispersed form, and the solids do not tend to settle out of the emulsion on standing. The emulsion may be forced through a series of baffles, screens or other obstructions whereby any undispersed or undissolved particles are broken up and sediment or other heavy foreign matter is allowed to settle out.

The emulsified and highly dilute coating fluid prepared in the disclosed manner is then conducted to the color cylinders of the machine and the coating operation is effected. Referring to Fig. 1 of the drawings, the web I2 of paper or other sheet material is moved at a uniform and comparatively high rate of speed on the lower I belt I9 under the lowest pair of color cylinders C.

The compressed air passing through atomizing spray nozzles N of the rotating and oscillating color cylinders breaks up the emulsified coating fluid into a cloud or mass of extremely fine mist of uniform density which is thrown on the surface of the web and forms a thin but uniform coating thereon. If the air pipes I 68 are used, the mist or spray isevenly distributed over the Web I2 by air jets from these pipes. This first coat is dried as the web I2 passes along the lowest blanket I6! and back on the undersurface of the next higher blanket, and due to the uniform dispersion of the solids in the sprayed emulsion, the dried coat is of uniform thickness. The returning web I2 then receives a second coat of material as it passes back over the lowest pair of color cylinders C and immediately thereafter receives a third coat as it passes under the next higher pair of horizontally aligned color cylinders. The coatings so applied dry as the web passes to the end of the machine section A and back, whereupon another coating of spray material is applied as the web passes over the intermediate color cylinders C. This operation is continued until the desired number of coats has been applied, and as previously explained, the opposite surface of the web I2 may be similarly coated with the same or different coating material by continuing the operation in section B of the machine. It will be noted that since the web I2 passes both below and above each set of color cylinders, two coats are simultaneously applied by each such set and the spray emanating from each color cylinder is substantially completely utilized.

It is not in all cases essential that the color cylinders be both oscillated and rotated and in some coating operations, either-rotation alone or oscillation alone may be suflicient to produce a uniform coat. As explained above, the disclosed color cylinders C may be arranged for rotative movement only by merely disconnecting or removing the cam follower springs 89, and oscillation without rotation may be obtained by removing the color cylinder driving gears 67. When the color cylinders are oscillated, either with or without rotation, it is preferable that the cams 64 driving the two cylinders C of each horizontally aligned pair be relatively reversed in order that the cylinders of each pair may be oscillated in opposite directions. When the color cylinders are rotated, the direction of rotation thereof is preferably opposite to the direction of movement of the web I2, as shown bythe arrows in Figs. 1 and 4.

It will be readily apparent that the process and apparatus of the invention include many advantageous features. Thus, for example, due to the fact that the coating isapplied in a plurality of separate layers or coats, a coating comprising a combination of layers of different coating materials can readily be obtained. This is of particular advantage, for example, where a. comparatively expensive color is desired. 0r dinarily, such color can be obtained only at considerable expense, since the color carrying material, if applied in a single coat, must be sufficiently heavy to fill the web surface and leave a layer of considerable body thereon. With my improved process however, the first coats ma comprise comparatively cheap filling, sizing 6: adhesive materials, and the desired color may then be applied as a thin final coat over the pre-. viously dried preliminary coats with considerable saving of the expensive coloring material.

Due to the uniformity of my extremely divided coating mist or spray and the uniform dispersion of the coating solids therein, the web may be propelled at very high speeds without streaking or striping the finish. In certain cases, an entirely uniform coating may be produced with a rate of web travel as fast as 1,000 feet per minute, and even at higher speeds, if required.

A modified form of coating machine is shown in Fig. 13. In this modification, the spray nozzles are oscillated transversely of the web to be coated but are not rotated. Referring to Fig. 13, the web 533 is carried by a moving suction blanket or other support H34 beneath two parallel trans-.

verse color cylinders I35 and I36. The color cylinders may beof substantially the same construction as that described above and are each provided with a plurality of spaced downwardly directed atomizing spray nozzles I3I. Color solution and air are fed to the spray cylinders through the flexible hoses I38 and I39. ,The color cylinder I35 is fixed to a transverse bar I40 slidably supported in blocks I II on one side of the vertical frames I 32v and I43, and the other color cylinder I 36 is similarly supported on alike sliding bar I44 on the opposite side of the frames as shown. Vertical arms I 45 and I46 are respectively fixed to the bars I40 and I44 and a flexible cable I41 passing over the pulleys I48 is clamped to these arms. One end of the cable I41 is attached to a crank M9 fixed to a suitably driven shaft I50 journaled in the frames I42 and I43. The cable passes upwardly from the crank I49, over a pulley I5I, then transversely across to the top of the frame I43 and back to the frame I42 over the pulleys I48, back transversely to the frame I43 and finally down over the pulley I52 to the freely hanging weight I53.

In the operation of the machine shown in Fig. 12, the web I33 is moved at a uniform rate past the color cylinders which project a mist of atomized emulsified coating material thereon. The

. color cylinders I35 and I36 are rapidly oscillated in opposite directions by the mechanism described, and this oscillation ensures the formation of a cloud of spray or mist of uniform density which settles on to and coats the surface of the web. I33. In this manner, a thin but extremely uniform layer of coating material is applied across the entire width of the web and no undesirable streaks or stripes of coating are produced. As in the case of the previously described machine, the color fluid employed preferably comprises a homogeneous emulsion of -the desired coating material or materials with a high percentage of water or other fluid, preferably produced by blowing air through a wateror other fluid mixture of the coating solids, and this emulsion is broken up into very fine mist by atomizing spray nozzles. I

I claim:

1. In a coating machine, in which a web of sheet material is treated, means for moving the web longitudinally, a plurality of spray nozzles disposed at points spaced transversely of and adjacent the path of movement of said web, means for supplying said nozzles with coating fluid and means for completely rotating said nozzles about an axis extending transversely of the v path of movement of said web and substantially parallel to the web surface on the side of the web .to which coating is applied.

web longitudinally, a plurality of spray nozzles spaced longitudinally along and circumferentially about a stationary axis extending transversely of the path of travel of said web and adjacent and substantially parallel to the surface thereof, means for supplying said nozzles with coating fluid and means for completely rotating said nozzles about said axis in a direction opposite to the direction of movement of said web.

3. In a coating machine, in which a web of sheet material is treated, means for moving the web longitudinally, a plurality of spray nozzles fixed to and spaced along an elongated member extending transversely of and adjacent the path of movement of said web, means for supplying said nozzles with coating fluid and means for simultaneously rotating said elongated member about an axis extending transversely of said web and substatnially parallel to the web surface on the side of the web to which coating is applied and oscillating said member along said axis.

4. In a coating machine, in which a web of sheet material is uniformly coated, means for moving the web longitudinally, at least two rows of substantially aligned connected spray nozzles spaced transversely of and lying adjacent to the path of travel of said web, means for supplying said nozzles with coating fluid whereby a spray is created over the web surface and means for simultaneously oscillating said rows of nozzles in opposite directions transversely of the path of travel of said web.

5. In a coating machine, in which a web .of sheet material is treated, means for moving the web longitudinally, at least two sets of connected spray nozzles, the nozzles of each set being spaced longitudinally along an axis extending transversely of and adjacent the path of travel of said web on the side of the web to which coating is applied, means for supplying all of said nozzles with coating fluid and means for completely rotating said nozzles about said respective transverse axes.

6. In a coating machine, in which a web of sheet material is treated, means for moving the web longitudinally, at least two sets of connected spray nozzles, the nozzles of each set being spaced longitudinally along an axis extending transversely of and adjacent the path of travel of said web on the side of the web to which coating is applied, means for supplying all of said nozzles with coating fluid, means for rotating said rows of nozzles about said respective axes and means for simultaneously oscillating both of said rows of nozzles along said respective axes.

7. In a coating machine, in which a web of sheet material is treated, means for continuously moving the web longitudinally, a cylindrical member extending transversely across the path of travel of said web and adjacent thereto, a plurality of spray nozzles spaced longitudinally along and extending substantially radially from said cylinder, a duct within said cylinder for conducting coating fluid to said nozzles and means for rotating said cylinder.

8. In a coating machine, in which. a web of sheet material is treated, means for continuously moving the web longitudinally, a cylindrical member extending transversely across the path of travel of said web and adjacent thereto, a plurality of atomizing spray nozzles on said cylinder spaced longitudinally along and distributed ci cumferentially about the surface of said cylindefi', ducts within said cylinder for conducting coating fluid and air to said nozzles and means for rotating said cylinder.

, means for distributing and further breaking up 9. In a coating machine, in which a web of sheet material is treated, means for continuously moving the web longitudinally, a substantially cylindrical member rotatably and axially movably supported with its axis extending transversely across the path of travel of said web, a plurality of spray nozzles spaced longitudinally along said cylinder, a duct in said cylinder for supplying coating fluid to said nozzles, a drive shaft adjacent one end of said cylinder, means connecting said shaft to rotate said cylinder, cammeans on said shaft and means operated by said cam means for oscillating said cylinder axially as it rotates.

10. In a coating machine, in which a web of sheet material is treated, means for moving the web longitudinally, a substantially cylindrical member having its axis extending transversely across the path of travel of said web and adjacent thereto, a plurality of spray nozzles on said cylinder at points spaced transversely of the path of travel of said web, means for supplying coating fluid to said nozzles, means f or rotating said cylinder, said nozzles being designed to spread a spray of coating fluid longitudinallyof saidcylinder substantially in planes passing through the cylindrical axis whereby the sprays from adjacent nozzles overlap as said cylinder rotates.

11. In a coating machine, a spraying device comprising an elongated rotary member having a plurality of spray nozzles at longitudinally spaced points thereon and means for supplying coating material to said nozzles, means for rotating said elongated member about its longitudinal axis whereby a spray of coating material is thrown out about said device, and means for continuously moving two spaced areas of a continuous web of sheet material in contact with the coating spray about said device.

12. In a coating machine, a pair of spaced substantially parallel elongated spraying devices each comprising a substantially cylindrical element carrying a plurality of spray nozzles at points spaced longitudinally thereof, means'for supplying liquid coating material to said nozzles, means for simultaneously rotating said devices about their cylindrical axes and oscillating said devices along said axes, means for continuously moving two spaced areas of a continuous web of sheet material transversely of said cylinders and jacent the path of travel of said web, means for supplying said nozzles with coating fluid, means for completely rotating said nozzles about an axis extending transversely across the path of travel of said web and substantially parallel to the web surface and means for directing jets of gaseous fluid into the coating fluid spray emanating from said nozzles adjacent the point where said spray contacts with said web.

14. In a coating machine, in which a web of sheet material is treated, means for moving the web longitudinaly, means disposed adjacent the path of travel of said web for throwing a spray of coatingfiuid on to the surface of said web and said spray along the web surface comprising at .least one jet of gaseous fluid striking the coating spray adjacent the surface of the web.

15. In a coating machine, in which a web of it arrears sheet material is treated, means for moving the web longitudinally, means disposed adjacent the path of travel of said web for discharging coating fluid under pressure in company with air under pressure in the form of a spray on to the surface of said web and means for distributing and further breaking up said coating fluid prior to its contact with the web surface comprising a plurality of jets of air moving in substantially the same direction as the moving web and striking the coating spray adjacent the surface of the web.

16. In a coating machine, in which a web of sheet material is treated, means for moving the web longitudinally, a plurality of spray nozzles disposed at points spaced transversely of and adjacent the path of travel of said web, means for supplying said nozzles with coating fluid, means for reciprocating said nozzles along an axis extending transversely of the path of travel of said web, means for directing jets of air into the coatingfluid spray emanating from the nozzles adjacent the point where said spray contacts with said web and means for reciprocating said air jet directing means transversely of the path of travel of said web.

17. In a coating machine, in which a Web of sheet material is treated, means for moving the web longitudinally, means disposed adjacent the path of travel of said web for throwing a spray of coating fluid on to the surface of said web, means for distributing said' spray along the web surface comprising at least one jet of gaseous fluid striking the coating spray adjacent the surface of the web and means for moving said jet transversely of the web surface.

18. A process of coating paper for printing purposes which comprises discharging liquid. coating material-under superatmospheric pressure in company with air under superatmospheric' pressure in the form of a spray on to the surface of a continuously advancing web of paper, and discharging jets of air under superatmospheric pressure into the spray as it approaches the web surface to further subdivide and distribute the spray.

'19. The process of coating sheet material which comprises discharging under superatmos-= pheric pressure a mass of coating material com prising finely divided solid material in a liquid carrier, impregnating a gas with a liquid having a low surface tension and discharging said gas under superatmospheric pressure in company with said liquid to subdivide said coating liquid and form a spray thereof the particles of which are sufiiciently small to be perceptibly subject to the buoyant effect of air, passing a web of sheet material adjacent said spray whereby a surface of said web is coated With said coating material.

JAMES D. MAcLAURIN.

Images