US2573052A - Liquid coating device - Google Patents

Description

R. H. PARKER LIQUID COATING DEVICE 2 SHEETS-SHEET 1 Filed Jan. 24, 1948 QM" W, 11953 w. H. PARKER LIQUID COATING DEVICE 2 SHEETS-SHEET 2 Filed Jan. 24, 1948 Iii J11 Patented Oct. 30, 1951 LIQUID COATING DEVICE Raymond H. Parker, Braintree, Mass.

Application January 24, 1948, Serial No. 4,175

' 6 Claims. 1

The present invention relates in general to liquid coating devices, and in particular to devices for applying a film of liquid adhesive to a sheet or strip of thin and flexible material like paper or cloth, or for applying water to thesurface of a dry coating of adhesive already in place upon such sheet for the purpose of activating the adhesive. Both these latter classes of devices are herein termed label pasters for present purposes.

The use of label pasters of prior design and construction has been fraught with various familiar drawbacks which have given rise to improper and defective operation of the devices and to annoyance and nuisance to their users. The prevailing employment of rollers to apply a coating of liquid adhesive to the backs of labels invariably creates a tendency for the leading edge of the label to adhere to the roller and follow it on down into the reservoir. or font of paste, glue, mucilage, or other liquid in which the roller is partially immersed in order to pick up the liquid which it is to apply to the label. When this occurs, it results in the paste getting on the wrong side of the label, as well as on theusers hands in extricating the label and in subsequently applying it to the package or other surface to which it is to remain attached. When clearingguides or fingers are provided in an endeavor to prevent this, by freeing the leading edge and following portions of the label from adhesion to the roller surface, the adhesive accumulates on these fingers because of their contact with the wetted undersurface of the label, and in many cases because they also make contact with the applying roller, causing buckling and interference with the proper emergence of the label, unless frequent cleaning is effected. The accumulation and oaking of the adhesive on other parts which have been provided in prior devices to assist in feeding,

guiding and freeing the labels, with resultant impeding of the free feeding and travel of the labels, likewise necessitates a waste of effort and time in cleaning these parts. This is particularly true of feed rollers employed in prior devices which press the label against the adhesive-applying roller to receive, the desired coating of adhesive, in that such feeding rollers make contact with the wetted surface of the applying roller except when a label intervenes, and thus are themselves coated more or less with adhesive which at best is transferred in varying degree to the wrong side of the label, which makes an obje c tionable smear when the label is applied to a package, blurring an address written in ordinary ink, and also gets on the users hands, and at worst if more tacky than the adhesive on the applying roller causes the label to adhere to and follow around the feeding rollers instead of emerging properly for grasping.

The object of the present invention is to improve the construction and method of operation of liquid coating devices and especially label pasters through obviating these and other faults, and particularly to provide a mechanism for applyinga liquid, gum, or solid to a flexible sheet material by means of a roller in such manner that adhesion of the flexible sheet material to the roller during and after the application will be rendered practically impossible, even in the absence of all mechanical devices for freeing the flexible material from the applying roller or for preventing its adhesion thereto. To this end, advantage is taken of the inherent resistance of a substantially inextensible sheet of material to bending both lengthwise and crosswise at the same time, and thus through forming a trough or valley in the sheet extending longitudinally thereof, i. e. in the direction of its movement, to stiffen the sheet against transverse bending and thus render it impossible or substantially so for the sheet to adhere to and follow around the periphery of the applying roller over and in contact with which it is traveling in order to receive a coating of adhesive or other material. Thus, the applying roller is given the necessary or desired shape in profile to form or maintain the longitudinal trough in the flexible material which is passed over it, and pressing means in the form of a roller or plurality of rollers, or a stationary element, or both, is provided, preferably having or defining a contour in profile complementary to that of the applying roller, to force the sheet or strip of flexible material into contact with the profile of the applying roller throughout substantially the entire width of the strip. The coated strip, being thus stiffened by the trough formed longitudinally therein through the interaction of the rollers or other elements between which it is passed, is forced to leave the applying roller at a tangent, and by reason of its stiffness stands out from all the parts of the device without need for any mechanical support and can be easily grasped by the users hand while the latter is clear of all parts of the device, or received and applied to the desired surface of a package automatically by supplemental label-applying mechanism.

To obviate the undesired transfer of adhesive to the feeding rollers which engage the face of the flexible strip or label, these rollers are preferably spaced from the applying roller so that they never make contact therewith, even in the absence of an interposed flexible strip or label. This is possible with an applying roller of convex profile, but is best accomplished by the use of an applying roller of concave profile, since the natural tendency of the flexible strip or label to maintain its initial flat relation and thus to resist being bent into a trough causes all parts of the width of the strip to conform automatically to the concave profile of the applying roller without the need to squeeze the strip into contact therewith by an auxiliary roller as is necessary where the standard cylindrical applying roller with its straight profile is employed. Thus there is no gumming-up of the feeding rollers in use, and the nuisance of frequently cleaning such rollers or trying to keep them free from adhesive is entirely avoided.

Since no clearing-guides or fingers are required to free or guide the leading edge and following portions of the flexible strip from the applying roller, there is'no longer any problem of keeping such guides freed from an accumulation of adhesive.

Other objects of the-invention, and the manner of their attainment, are made plain in the following description.

Illustrative embodiments of the invention are shown in the accompanying drawings, in which Fig. l is a plan view of the-preferred form of the invention.

Fig. 2 is a vertical section on line 2-2 of Fig. 1.

Fig. 3 is an elevation taken from the left-hand end of Fig. 1.

Fig. 4 is a. diagrammatic vertical section corresponding to Fig. 2 showing an alternative form.

Fig. 5 shows in elevation thefeeding roller of Figs. 1 to 3', mounted on its shaft.

Figs. 6 and '7 show in side elevation a feeding roller and applying roller respectively, made in an alternative form to those shown in Figs. 1 to 4.

Figs. 8, 9, 10, and 11' show still-other alternative forms of the feeding roller of Fig. 3.

In the embodiment of Figs. 1 to'3, a rectangular box-like receptacle I having a tight bottom 3 and side and end-walls 5, 1, respectively, serves both as the frame of the device and as the reservoir or font for the adhesive or other liquid to be applied. This reservoir is provided with integral webs 8 serving as legs. A shaft 9, rotating in bearings constituted by the bottoms of slots l I cut in side-walls 5, has-fixed thereon an apply-- ing roller l3 which is immersed in the liquid in reservoir l to such an' extent that its surface will be wetted throughout its entire length. The applying roller [3 has the shape of a concave spindle whose profile is the arc of a circle. Applied plates l5 held to theoutside ends 5 of reservoir I by screws ll, Fig. 2, have their upper ends slotted at I9 to form bearings for a second shaft 2| on which is fixed'a feed roller 23 of rubber or other high-friction material having a fiat tread. The bottoms of slots H and I9 are so spaced with respect to each other and to' the diameters of shafts 9 and 2| and rollers l3 and 23 that the surfaces of the latter rollers do not make contact with each other. Though they approach closely to each other, there is clearance between their opposing surfaces.

Intermeshing gears 25, 21, are respectively fixed on the shafts 9 and 2| of the two rollers, by means of set screws 29 put through their hubs, and bearing against the respectiveshafts, to rotate the two rollers simultaneously in opposite directions, means being provided for driving one of the shafts, herein a crank 3| adapted for manual operation, fixed on the end of applying roller shaft 9.

To guide the labels into position between the applying roller l3 and feed roller 23, a feed platform 33 is provided, of which the top surface is curved to conform to the profile of applying roller [3 and thus has the shape of a portion of a cylinder. The inward end 35 of this platform 33 conforms closely to the shape of the applying rollers surface, but has a slight clearance therefrom throughout its length, and at all points is preferably slightly below the level of the top of applying roller l3. The feed platform is mounted on reservoir I by means of its legs 3! integral therewith and downturned to enter within the reservoir I, being fixed to the side-walls 5 thereof by screws 39 passing through slots 4| in the legs permitting adjustment of the platform 33 toward and from applying roller [3, and also tilting of the platform when desired to lift or lower its inward edge 35. Supports 43 which serve a purpose to be explained. later herein are interposed between legs 3'! of the platform and the inner surfaces of ends 5 of the reservoir, so as to be also retained in position by the same screws 39.

The feed roller 23 is set so that it presses lightly on and rubs against the inner end of feed platform 33; in practice, the platform actually supports the weight of roller 23. This is to insure a sufficient degree of frictional contact between the lowermost point of roller .23 and a strip or label 44 fed inward by hand over and along platform 33 into the nip between feed roller 23 and such platform, to cause the further feeding of the label through the space between the two rollers when feed roller 23 is rotated counter-clockwise in Fig. 2. In other words, the feed of the strip or label 44 through the device is effected by frictional engagement between the feed roller and the strip or label supported by and sliding over the immediately underlying point on feed platform 33.

The feed .platform33 need not be formed concave as shown. In fact, a flat platform works equally well with most of the grades and qualities of paper used for labels. However, by giving the feed platform the transversely concaved shape shown and described, the strip or label which is to be wetted or coated with adhesive is preformed into the longitudinally extending trough shape (which as more fully explained hereinafter stiffens the label in order to make it -leave the applying roller at a tangent), both by the holding-down action of the feed roller and by the simple and natural act of pressing it into conformity with the feed platform with the fingers of the users hand in sliding the leading edge of the label into the nip between the feed roller and the feed platform. This aids in attaining complete conformity of the label to the curve of the applying rollers profile, and the avoidance of puckering of the label.

The continuance of the feeding is effected through rotation of the feeding roller in the direction indicated in Fig. 2, by means of handcrank 3|, thus bringing first the leading edge and then the following portions of the under surface of the label into contact with the wetted surface of the applying roller l3, or with the film of adhesive carried thereby. This contact tends to occur throughout the entire width of the label, partly on account of thelatters effort to resume its original plane relation, even though only the middle portion of the width of the label is held depressed in the deepest or lowermost part of the concave profile of applying roller l3 by feeding roller IS. The conjoint action of the two rollers results in the maintenance of the desired longitudinally extending trough or valley in the strip of label, initiated by holding it down into conformity with the transversely curved feed platform 33, and continuing over the applying roller l3 to persist for an indefinite extent beyond the latter roller.

Because of the stiffening of the strip or label by this longitudinal trough, its resistance to bending transversely is so greatly increased as to render it incapable of being drawn on around the curve of the peripheral surface of applying roller l3, and compels it to stand out, without any need for mechanical support, at a slight upwardly inclined angle to platform 33 which angle as shown in Fig. 2 is such that thelabel is tangent to the applying roller I3 at a short distance past the line joining this rollers center with the center of the feeding roller. Thus projected outwardly, it is simple for the user to grasp the gummed label as its trailing edge reaches the applying roller, and remove it for application to the surface of the package to which it is intended to be aflixed, or for the feed devices of an automatic label-applying machine (not shown) to receive and apply the label.

The surface travel of the applying roller [3 differs from that of the under surface of the label which makes contact with such roller, even when the two rollers are driven at the same angularispeed by gears 25, 27, since the diameter of the applying roller 13' varies from greater to less than the diameter of feeding roller 23. Hence there is a wiping action of the applying roller l3 against the under surface of the label which assures complete coverage and equal distribution of the adhesive or other liquid over the entire area of the label.

To prevent puckering or buckling of the leading edge of fairly wide labels made out of thin stock, which sometimes occurs through manually feeding the label along the feed table 33 faster than feed roller 23 is traveling, and through other causes, pressers 45 are provided in the form of two light metal plates, one located at each side of feed roller 23. These pressers are suspended in forwardly and downwardly inclined relation above the path of the label by having their upper edges bent into U-shape and hooked over a supporting rod 41 which is fixed in the upper ends of supports 43. The lower edges of these pressers are shaped to conform exactly to the cylindrical curvature and the terminal curve of feed table 33 and to be in exact register with the inner end 35 of this feed table. The two pressers are held clear of feed roll 23 by collars 49 fixed on supporting rod 41. Thus disposed, these pressers ride lightly over the top surface of the label at each side of feed roller 23 as the label advances, smoothing down any bulges and puckers in the label to make sure that all areas of the labels under surface are brought into contact with the applying roller and to prevent any arching of portions of the label away from the feed table at its line of departure therefrom which might result in imperfectly coating the label.

A scraper is provided at the rising side of applying roller [3, having its edge shaped to conform exactly to the profile of such roller, and adjusted into the proper proximity t applying roller l3 to pass the desired thickness of film of adhesive on the roller, scraping back any excess thickness and any lumps or clots which might be picked up by the roller in passing through the supply of adhesive in the reservoir. This scraper is adjustably mounted by means of thumb screws 53 passing through slots in scraper 5| and threaded into lugs extending in from the rim of reservoir I and which support the scraper.

The device is adapted to be cleaned with the utmost facility, by reason of the mounting of the rollers in open bearings l I, I9, and by reason of the mere hanging of pressers 45 on rod 41; these parts can thus be removed instantly for cleaning, which also leaves the interior of the reservoir accessible for cleaning, though the necessity for such arises at infrequent intervals.

The curved feed platform 33, as previously noted, is normally set so that if it were to be extended it would intersect applying roller [3 just below, and in a curve parallel to, the profile of the applying roller at its topmost point. That is, as shown in Figs. 2 and 3, the path of the advancing label cuts the applying roller a slight distance below the level of the top of the latter. So long as the lowest point in the concave profile of the applying roller is above the level of the path of the label as defined by the feed platform, and so long as some means is provided to hold the label down onto the feed platform and thus below the level of the top profile of the applying roller, as by the feed roller 23, the trough-like form of the advancing label creates a force in the label tending to maintain its course in the same path or level as that in which it has been traveling along the surface of the feed platform. That is, once the trough has been formed, the label resists the upward inclination which it must assume in order to get over the slightly higher top surface of the applying roller. Hence if the intermediate portion of the width of the label is held down sufiiciently to reach the bottom of the curve of the applying rollers profile, the portions of the label lying outwardly of such intermediate portion will take care of themselves and make contact with the parts of the applying roller which are of greater diameter, in their effort to flatten out the trough so as to be able to make the transverse bend to which they are impelled through being forced to rise from the level of the feeding table in order to get over the applying roller which is elevated with respect to such plane. Therefore if the label is presented to the applying roller by any means which will present it in a path intersecting the surface of the upper half of the applying roller at or below the lowest point of its curved top profile, whether the label reaches the applying roller in plane or trough-shaped relation, this described force will be brought into action to insure a substantially complete conformation of the label to this concave curved profile. For this reason, it is unnecessary in most cases to shape the feeding roller so that it conforms to the curvature of the concave profile of the applying roller.

Another embodiment of the invention illustrating and utilizing the principle just recited is shown in partly diagrammatic form in Fig. 4. Therein, a concave roller 65 similar to that of the form of Figs. 1 to 3 is mounted to dip into the liquid maintained in a reservoir 63 in analogous manner to that fully described in connection with the form of Fig. 1, but instead of the concave feeding platform of Fig. 1 a flat feeding platform 6! is used, over which the strip or label is fed'manually in plane relation to the.

nip of a pair of. feeding rollers 69 which" are cylindrical and driven in opposite directions. at the same surface speed. These feed rollers 69 are substantially equal in length to applying roller 65 and are pressed together. to seize: and feed forward the label entered into their nip.

Feed platform" 61 is extended beyond the feed rollers 69 into close proximity with the surface of applying roller 65,. having its plane inward endforrned, just. as in thecase of curved feed platform 33 in Fig. 1 in a curve: complementary tothat of the surfaceof the applying roller taken in the plane of extent of feeding platform 61,. so that there is a slight but uniform clearance. between the rollandthe inward endof the platform throughout the length of the roller. In order to locate the nip of feed roller 69 in the plane of the top surface of feeding platform 67, a trough H is formed in the platform to receive the bottom feed roller.

A presser i3 is provided to force the label fed by rollers 89 into conformity with the concave profile of applying roller 65. The inner end of this presser, like the corresponding end of feed platform 61, is shaped to match the curve of the profile of applying roller 65 throughout the latters length and to have slight and uniform clearance therefrom, and is also spaced a sufficient distance above platform 61 to afford free egress of the label, but is located below the top profile of the applying roller at all points in the latters length. The material forming the presser T3 is extended back over the feed rollers 69 to form a housing therefor and also to enable itto be supported by suitable attachment to the bearings or other supporting structure (not shown) for the feed rollers.

Feed rollers 69 are driven in unison with applying roller' 65 by gears ll fixed respectively on the shaft of the applying roller and on the shaft 8| of the bottom feed roller, either of these shafts as preferred being rotated by a hand-crank (not shown) as in the first embodiment, and the top feed roller being driven through frictional engagement with the bottom roller. The rollers are so disposed that the plane tangent to these rollers at their nip intersects the applying roller below the lowest point in the concave top profile of the latter roller. These feed rollers are made from or surfaced with rubber or other highfriction material.

When a label is advanced manually into the nip of rotating feed rollers 69 and by the latter fed through the space between the inner end of the feed table and the overlying presser l3, first the corners of its leading edge and then the portions progressively nearer its longitudinal central line bear against the surface of applying roller 55 until the under surface of the label is in contact with the applying roller across the entire width of the label. of the label are raised by the parts of the applying roller which are of medium to greater diameter, while the middle portion of the width of the label is held depressed in the deepest or lowermost part of the concave profile of the applying roller through the action of presser 13. This results in the formation of the desired longitudinally extending trough or valley in the strip or label that prevents it from adhering to and following the surface of the applying roller, and which trough starts between the feeding rollers and the presser, continues over the applying The lateral portionsroller 65,. and persists for an indefinite extent beyond the latter roller;

In this embodiment, full contact between the surface of the applying. roller and the label over the entire area of the latters under surface is accomplished not only through the aforesaid effort of the label to flatten out the trough in order to get over the relatively elevated top surface of applying. roller 65, but also because the label is. held down onto the surface of the applying. roller throughoutits entire width by presser 13'.

The positive feed. throughout the entire width of the label by feed rollers 69 is of special advantage in overcoming any tendency of relatively wide labels made out of thin stock to pucker or bulge upward locally asthey reach the applying roller, and. to overcome the same faults in the coating or wettingof much greater. sheets of thin and flexible material. for purposes other than for use as labels Where the device is to be used for labels of relatively great variations in width, the applying roller is advantageously given the shape shown in Fig. 11, inv which the part-circular arc of its profile is interrupted at midlength by a zone 81. having a profile 89 defined by theme of a circle which is: of. much shorter radius than that of. are 85. It has been found that when narrow labels are fed. over. the uninterrupted single-arc profile of the applying roller of Fig. l, the trough. is not deep enough to resist. the adhesion of the label to the applying roller every time, and the label is sometimes carried around and. into the reservoir. But by giving. the roller the. central zone 81 having. a profile of sharper curvature, and employing such. roller with the presser roller 23in the structure of Fig. 1, the trough formed in a narrow label fed over this zone. isdeepened and thus renders the label stiff enoughzto. achieve and maintain the desired tangential relation to the applying roller as it passes thereover. When a wide label is fed over such an applying roller, the portions traversing the several. zones assume: the. curvature of their respective zones without difiiculty,.the label issuing in concave and slightly corrugated form which imparts slightly greater resistance to transverse bendingthanwith the single-arc roller of Fig. 1.

The utilization-of the invention principle is in no way dependent on the use of the particular rollers. and pressers described, or of a segment of a circle; for the profile of the applying roller. Such have. simply been found to give good-results in coating the entire areas ofthe more common. sizes of labels using paper stock of average thickness and quality. An applying roller having the shape in profile of a hyperbola is useful in certain instances, as where the part-circular profile sometimes has'a tendency to provoke longitudinal wrinkling of labels of thinner stock or ones whichare more quickly permeated andrendered limp by the solvent in the adhesive. In fact, a continuous curve for the profile is not even necessary in cases where it is not important to coat the entire. under side of the label. In these instances, an applying roller having its concave profile defined by straight lines as shown in Fig. 7 willwork successfully.

In lieu of the cylindrical feed rollers and pressers of Figs. 1 and 4, a single feed roller as long as the applying roller and of convex contour complementary thereto, making no contact with the applying roller, can be used. Thus, the applying roller of Fig. 7 can be combined with a feeding roller of matching convex contour such as shown in Fig. 6. A full-length feeding roller of the type shown in Fig. 8 will also work successfully with the hyperbolically curved surface of applying roller described, because of the aforesaid tendency of the label to conform to the profile of the applying roller when fed to the latter in a plane intersectin the latter below the lowest point of its profile. A double roller in the form of Fig. 10 can also be substituted for the single roller of Figs. 1 and 5. Fig. 9 is a variant of the feeding roller of Fig. 6, illustrating the combination of curved and straight lines defining the convex profile of an alternative form of feeding roller 23; in Fig. 9, two truncated conoids have their bases separated by an intervening section of cylindrical shape. From these examples, it will be made plain that a variety of shapes of applying and feeding rollers can be employed without departing from the principles of the invention.

While I have illustrated and described certain forms in which the invention may be embodied, I am aware that many modifications may be made therein by any person skilled in the art, without departing from the scope of the invention as expressed in the claims. Therefore, I do not wish to be limited to the particular forms shown, or to the details of construction thereof, but what Ido claim is:

1. A liquid coating device for flat flexible sheet material having in combination a container for the liquid coating material, a liquid applying roller having a concave profile, means for supporting said roller so that its outer surface is immersed in the liquid coating material, a feed roller, means for rotatably supporting the feed roller above and adjacent to the coating roller with its axis parallel to that of the latter, and a guide plate mounted on the container having an edge thereof adjacent the coating roller, the feed roller being so positioned that it presses the sheet material against the guide plate and feeds the 10 material past and in contact with the coating roller.

2. A liquid coating device according to claim 1, in which the guide plate guides the sheet material to the applying roller in a path intersecting such roller below the lowest point in the concave top profile of such roller.

3. A liquid coating device according to claim 1, in which the feed roller is spaced from the applying roller at all times.

4. A liquid coating device according to claim 1, in which the guide plate is concave and shapes the sheet material into a trough fitting the profile of the applying roller before the sheet material makes contact with the applying roller.

5. A liquid coating device according to claim 4,

including means supported above the guide plate engaging the sheet material and maintainin the sheet material in contact with the guide plate at its said edge.

6. A liquid coating device according to claim 1, the liquid-applying roller having a concave profile in the form of a curve extending symmetrically from a zone at mid-length thereof, such central zone having a curvature of sharper slope than the adjacent portions lying outwardly thereof.

RAYMOND H. PARKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 675,007 Johnson May 28, 1901 1,077,126 Doughty Oct. 28, 1913 1,191,537 Schall July 18, 1916 1,347,182 Sleeper et a1 July 20, 1920 1,455,859 Brooks Ma 22, 1923 2,109,328 Capstick Feb. 22, 1938 2,117,432 Linscott May 17, 1938

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