US3285225A - Coating applicator - Google Patents

Description

2 Sheets-Sheet 1 N2 53 NNINVENTOR. CV/F/brd ecor QWI W A TTURNEYS Nov. 15, 1966 c. R. RECOR COATING APPLICATOR Filed May 2, 1963 Nov. 15, 1966 c. R. RECOR 3,285,225

COATING APPLI CATOR Filed May 2, 1965 2 Sheets-Sheet 2 mill INVFNTOR.

United States Patent 3,285,225 COATING APPLICATOR Clifford R. Recor, Beloit, Wis., assignor t0 Beloit Corporation, Beloit, Wis., a corporation of Wisconsin Filed May 2, 1963, Ser. No. 277,627 4 Claims. (Cl. 118410) This invention relates to improvements in coating porous webs such as webs of paper or the like, and more particularly, to an improved apparatus for applying coatings topaper webs.

The instant invention is directed to a coating apparatus for obtaining a highly uniform deposit of a coating formulation onto a surface of a trevaling web. Although the apparatus is applicable to traveling webs of paper, plastic, cloth, metal sheets. etc., the invention will be described primarily in connection wtih paper webs. Modern coating practice involves relatively high speeds of travel for the web and a relatively limited area in which the coating is to be applied to the web and metered or smoothed onto the web in the desired weight and uniformity. The weight at which coatings are applied to webs is generally expressed by those skilled in the art in terms of pounds per unit of area, such as pounds perpaper ream. The coating compositions as such are generally referred to in the art on the basis of their solids content, which characterizes the coating compositions to the extent necessary for the skilled worker in the art. The instant invention affords an apparatus for the application of relatively high coating weights at comparatively high operating speeds (generally expressed in feet per minute of longitudinal travel of the web), in such a manner as to obtain superior uniformity of application and penetration of the web surface by the coating composition.

It is, therefore, an important object of the instant invention to provide an improved coating apparatus.

It is a further object of the instant invention to provide an improved coating apparatus for obtaining superior uniformity of application of the coating, superior penetration of the coating composition into surface portions of the web, improved coating speeds and improved coating finish on the web.

Other and further objects, features and advantages of v the present invention will become apparent to those skilled in the art from the following detailed disclosure thereof and the drawings attached hereto and made a part hereof.

On the drawings:

FIGURE 1 is a fragmentary side elevational view showing essential elements of the coating device of the invention;

FIGURE 2 is a fragmentary top plan view of the coating chamber of the invention shown in FIGURE 1 taken substantially along the line 11-11 of FIGURE 1 with certain parts including the upper roll removed;

FIGURE 3 is a sectional elevational view taken substantially along the line IIIIII of FIGURE 2;

FIGURE 4 is a detail sectional elevational view taken substantially along the line IVIV of FIGURE 3; and

FIGURE 5 is a diagrammatic elevational view of the overall assembly of the instant coating device.

As shown on the drawings:

The coating device indicated generally at in FIG- URES 1 and 5 hereof is a coating device for a web W traveling longitudinally (in the direction indicated by the arrows) over a transverse supporting device, which is preferably a supporting roll 11 rotatable about a transverse axis 11a and substantially transversely coextensive along its peripheral surface with the web W. In the instant specification and claims the direction of the web travel is referred to as the longitudinal direction and the cross machine direction or the direction of the width of the wab is referred to generally as the transverse direction. Reference to elements at the oncoming side of a given location refers to the oncoming side in the longitudinal direction and reference to elements at the off-running side of a given location refers to the off-running side in the lnogitudinal direction of the web travel.

From FIGURE 5, it will be seen that the web W travels around the rotating roll 11 and is firmly supported on the surface thereof as it passes a coating device indicated generally by the reference numeral 12. At the off-running side of the coating device 12 a trailing blade 13 is preferably mounted in conventional manner for the purpose of smoothing the coating carried on the web W. In general the coating device 12 applies a predetermined amount of coating to the web W and the trailing blade 13 is employed primarily for smoothing purposes, although it will be appreciated that the trailing blade 13 might be employed for removal of excess coating, if it is desired to apply excess coating to the web via the instant coating device 12, and in such instance excess coating might be returned to the coating pan indicated at 14 in FIGURE 5 and in FIGURE 1.

Referring to FIGURES 1 and 4, it will be seen that the coating device 12 comprises a shallow open topped coating chamber indicated at C in FIGURE 1 defined between the web covered roll 11 and an arcuately contoured bottom wall or floor 21 having substantially the contour of the periphery of the roll 11. In fact, in the instant device the radius for the roll 11 is substantially 16 inches and the radius of the arcuate contour of the chamber floor 21 is substantially inch greater.

As indicated in FIGURE 4, the chamber is provided with side walls, one of which is shown at 21a (and the other of which is shown at 21b in FIGURE 1) for close running operation with the sides of the roll 11. In addition, the floor 21 of the chamber C is provided with a generally transverse oncoming edge 21c which receives the web W traveling on the roll 11 and is positioned in sufficiently close running relation thereto to effectively assist in the retention of compressive forces on the coating in the chamber C which is in the form of a film indicated at F in full view in FIGURE 4. The web W is also indicated in full view, but shown only partially in FIG- URE 4 to avoid obscuring the position of the other elements. The chamber floor 21 is also provided with an off-running transverse edge 21d and this off-running edge 21d may itself function as a dam for metering the coating layer carried away from the chamber C on the web W. If desired, a blade or knife 22 may be adapted by suitable means such as bolts 23 along the off-running edge 21d to function as a coating metering device or dam. The web W backed by the roll 11 is driven through the chamber C and against the coating film F under substantial compressive forces, which are of course increased by the hydraulic wedge effect that is obtained as the roll drives the web against the film with decreasing radial clearance in the direction of the off-running chamber edge 21d.

It will thus be appreciated that the shallow coating chamber C is provided w th a first surface portion 21c co-nforming generally with the roll 11 toward the oncoming edge 21c and defining a narrow transverse slot with the roll 11 to receive the web W at the oncoming side. The chamber floor 21 also has a second surface portion 21 conforming generally with the roll 11 toward the off-running edge 21d defining a metering slot for the coating on the web passing therethrough, either with the off-running edge 21d or with the additional knife edge 22. As is indicated in dotted lines in FIGURE 1, the off-running floor portion 21] converges with the roll 11 carrying the web W thereon toward the trailing edge 21d.

Referring again to FIGURE 4, however, it will be seen that the oncoming and'off-runing edges 21c and 21d are coplanar, lying in the plane P-1 and the floor portions 21e and '21 of the chamber converge toward these edges, respectively, in defining the contour of the bottom of the chamber C.

' Coating is, of course, removed from the chamber C on the web W past the trailing edge 21d or the dam 22 and additional coating must be aded to the film F during the operation. This is done via a multiplicity of small generally transversely spaced passageways 25, 25, etc. which are aimed at the web W, generally perpendicularly thereto and in general radial alignment with the roll 11 itself, so that coating may be added under pressure directly against the web surface for obtaining the desired penetration of coating into the web surface. A relatively large transversely extending passageway 26 is mounted directly beneath the radial passages 25 for feeding coating under pressure upwardly into the passages 25. The transverse passageway 26 is fed by coating under pressure from a suitable source indicated diagrammatically at S in FIG- URE 1 into side entrances 27 at one or both ends of the transverse passageway 26 and the coating under high pressure passes through the relatively restricted lower ends 25a of the radial passages 25. The restricted passages 25a are employed for ease of maintenance of a substantially uniform pressure across the entire width of the transverse passageway 26, so that the flow of coating upwardly through each of the generally radially aligned passages 25 will be substantially uniform. The pressures generated in the chamber C, however, are quite substantial so the chamber floor wall 21g is of substantial thickness and the radially aligned passages are of substantial length beyond the narrow restricted entrances 25a, and the passages 25 are flared or opened at their mouths 25b. It will be appreciated that the floor portion 21g for the chamber C is formed of two mating elements shown in FIGURE 4 as a bottom element 21k seating a nested upper element 21 so that the complete radial passage 25 shown in FIGURE 4 is apparent. Actually, each passage 25 extends upwardly from the restricted bottom 25a to a first enlargement 250 in the element 21k, then to a second enlargement 25d feeding into a [laterally aligned shallow pressure equalizing slot 26a interconnecting the passages 25 (and shown in top plan lview in FIGURE 2), and then (referring back to FIGURE 4) the second enlargement 25d has a radial extension 256 in the upper element 21 which feeds to the flared opening 25b. In FIGURES 2 and 3, the upper nested element 21 is removed for simplification of the showing in the drawings. The upper nested element 21 is, of course, secured to the lower element 21k to form the composite floor 21g by suitable means such as bolts (e.g. at 21x) or the like.

Referring also to FIGURES 2 and 3, it will be seen that edge coating lines 30, 30 feed into a slot 31 aligned substantially with the edge of the web along the upper faceof the chamber, and a water seal slot 32 is provided immediately outside of the coating slot 31 and connected through a suitable passageway 33 to water under pressure for effecting the desired seal and to and drying at the ends or edges.

Referring also to FIGURE 1, it will be noted that an upright frame supported on the floor indicated at 41 carries a pivot 42 which swings a mounting arm 43 carrying a frame element 44 with a pivot pin 45 therein. The pivot pin 45 carries a generally horizontal frame element 46 that supports the coating chamber structure indicated generally at 12 and mounts the same for limited tilting movement about the pivot 45 which is adjacent the oncoming edge 21c. A set screw and lock nut as sembly 47 is mounted beneath the horizontal frame 46 for adjustably tilting the frame 46 and thereby adjusting the clearance between the roll 11 land the chamber trailing edge 21d (and the end dam 22, whichever is used to determine the final clearance in the operation of the coating device).

The coating pan 14 previously mentioned is also carried prevent coagulation in conventional manner on the swinging arm 43; which is mounted for pivotal movement about the transverse axis for the pivot 42. The transverse axis for the pivot 42 is spaced substantially from the transverse axis for the pivot 45 and afford swinging movement for the arm 43 in and out of operating position and also into operating position by virtue of the fluid motor 48 which is a conventional pneumatic cylinder resiliently urging the chamber C, with the coating film F therein, against the web W on the roll 11.

A specific example of a coating composition used in the practice of the instant invention has the following formulation (with all parts given by weight as is conventional):

7 Parts Clay Titanium dioxide 10 Casein 4 Latex adhesive (Dow Latex 512L-Solid Spaces) 12 Ammonium hydroxide (28%) 0.6 Ammonium stearate 2 Water 156 The above formulation has a solids content of about 43% and a viscosity of approximately 550 centipoises, although viscosities within the range of about to about 1500 centipoises can be used conveniently herein and viscosities of as much as 30,000 centipoises can be used with adequate pumping means for forcing the coating into the location of the film F. This permits the use of coatings from a minimum practical solids proportion of about 30% to a maximum practical solids proportion of about 65%. The foregoing 43% solids coating is applied in the practice of the instant invention maintaining about 10 pounds per square inch on the film F for the application of coating weight of about 7 pounds per ream at an operating speed of 1000 feet per minute. Coating weights in the range of 5 to 30 pounds per ream may be employed in the practice of the instant invention at speeds ofsubstantially 300 to 2500 feet per minute.

It'will be understood that modifications and variations may be effected with-out departing from the spirit and scope of the novel concepts of the present invention.

I claim as my invention:

1. .A coating device for a web travelling longitudinally, comprising a rotary support roll substantially transversely coextensive with and moving with the web supported thereby, means defining a shallow coating chamber spaced from said roll and having a first surface portion conforming generally with said roll toward an on-coming edge defining anarrow transverse slot with the roll to receive the web at the on-coming side and having a second surface portion conforming generally with said roll toward an offrunning edge defining a narrow transverse slot for meter-- ing coating onto the web passing therethrough, and means defining a multiplicity of passageways in said chamber intermediate said surface portions aimed toward said roll for urging coating under pressure against the web on the roll, and means for tilting said chamber about a transverse axis for selectively moving said off-running edge toward and away from said roll to control metering of the coating and means for swinging said transverse axis about a second transverse axis remote from the roll surface for selectively moving said chamber toward and away from said roll to control pressure loading of the coating against the web on the roll.

2. A coating device for a web travelling longitudinally, com-prlsing a rotary support roll substantially transversely coextensive with 'and moving with the web supported thereby, means defining a shallow coating chamber spaced from said roll and having a first surface portion conformmg generally with said roll toward an on-coming edge defining a narrow transverse slot with the roll to receive the web at the on-coming side and having a second surfaceportion conforming generally with said roll toward an off-running edge defining a narrow transverse slot for metering coating onto the web passing therethrough, means defining a multiplicity of passageways in said chamber intermediate said surface portions aimed toward said roll for urging coating under pressure against the web on the roll, means for tilting said chamber about a transverse axis for selectively moving said off-running edge toward and away from said roll to control metering of the coating, and fluid pressure actuated arms swinging said chamber about a second transverse axis remote from the roll surface for selectively moving said chamber toward and away from said roll to control pressure loading of the coating against the web on the roll.

3. A device adapted to apply coating to a web travelling longitudinally over a transverse suppotrt, comprising means defining a shallow open-topped chamber between longitudinaly spaced transverse co-plana-r edges and having opposed transverse surface portions converging upwardly from a bottom portion with the plane of said edges respectively toward each of said edges, means defining a multiplicity of passageways transversely spaced along said bottom and aimed at said plane, means defining a transverse passageway adapted to feed coating under pressure into said chamber through said multiplicity of passageways, means for tilting said chamber about a first transverse axis adjacent said edges, and fluid pressure actuated resilient means for swinging said chamber about a second transverse axis spaced from the first axis.

4. A coating device for a web travelling longitudinally, comprising a rotary support roll substantially transversely coextensive with and moving with the web supported thereby, means defining a shallow open-topped chamber between longitudinally spaced transverse coplanar edges in close running relation to said roll and having opposed transverse surface portions converging upwardly from a bottom position with the plane of said edges respectively toward each of said edges, means defining a multiplicity of passageways transversely spaced along said bottom and aimed at said plane, means defining a transverse passageway adapted to feed coating under pressure into said chamber through said'multiplicity of passageways, means for tilting said chamber about a first transverse axis adjacent said edges, and fluid pressure actuated resilient means for swinging said chamber about a second transverse axis spaced from the first axis.

References Cited by the Examiner UNITED STATES PATENTS 2,190,809 2/ 1940 Strauch 118-413 2,243,333 5/1941 Diescher 118-410 2,349,256 5/ 1944 Evans 118-411 2,464,771 3/ 1949 Van Guelpen 118-413 X 2,937,955 5/ 1960 Loomer 117-111 X 3,029,780 4/1962 Justus et al 117-126 3,063,868 11/1962 Brandsma et al. 117-120 X 3,079,889 3/1963 Jacobs et al 118-413 X 3,097,107 7/ 1963 Martinek 117-111 X ALFRED L. LEAVITT, Primary Examiner.

JOSEPH B. SPENCER Examiner.

I. M. BATTEN, 111., Assistant Examiner.

Claims (1)

1. A COATING DEVICE FOR A WEB TRAVELING LONGITUDINALLY, COMPRISING A ROTARY SUPPORT ROLL SUBSTANTIALLY TRANSVERSELY COEXTENSIVE WITH AND MOVING WITH THE WEB SUPPORTED THEREBY, MEANS DEFINING A SHALLOW COATING CHAMBER SPACED FROM SAID ROLL AND HAVING A FIRST SURFACE PORTION CONFORMING GENERALLY WITH SAID ROLL TOWARD AN ON-COMING EDGE DEFINING A NARROW TRANSVERSE SLOT WITH THE ROLL TO RECEIVE THE WEB AT THE ON-COMING SIDE AND HAVING A SECOND SURFACE PORTION CONFORMING GENERALLY WITH SAID ROLL TOWARD AN OFFRUNNING EDGE DEFINING A NARROW TRANSVERSE SLOT FOR METERING COATING ONTO THE WEB PASSING THERETHROUGH, AND MEANS DEFINING A MULTIPLICITY OF PASSAGEWAYS IN SAID CHAMBER INTERMEDIATE SAID SURFACE, PORTIONS AIMED TOWARD SAID ROLL FOR URGING COATNG UNDER PRESSURE AGAINST THE WEB ON THE ROLL, AND MEANS FOR TILTING SAID CHAMBER ABOUT A TRANSVERSE AXIS FOR SELECTIVELY MOVING SAID OFF-RUNNING EDGE TOWARD AND AWAY FROM SAID ROLL TO CONTROL METERING OF THE COATING AND MEANS FOR SWINGING SAID TRANSVERSE AXIS ABOUT A SECOND TRANSVERSE AXIS REMOTE FROM THE ROLL SURFACE FOR SELECTIVELY MOVING SAID CHAMBER TOWARD AND AWAY FROM SAID ROLL TO CONTROL PRESSURE LOADING OF THE COATING AGAINST THE WEB ON THE ROLL.

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