US2289798A

US2289798A - Coating apparatus

Info

Publication number: US2289798A
Application number: US317925A
Authority: US
Inventors: Gale F Nadeau; Eugene R Clearman
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1940-02-08
Filing date: 1940-02-08
Publication date: 1942-07-14
Anticipated expiration: 1959-07-14
Also published as: GB540517A; DE747615C

Description

y 1942- G. F. NADEAU ETAL 2,289,798

COATING APPARATUS Filed Feb. 8, 1940 2 She ets-Sheet l Ill Gaff/$540520 fUGENE/QCLEARMAN ATTORNEYS y 1942- I G1 F. NADEAU ET AL 2,289,798

COATING APPARATUS Filed' Feb. 8, 1940 2 Sheets-Sheet 2 GALE ENAoL-"Au fueE/YE/QCwARMA/v in the air, it has been Patented July 14, 19 42 2,289,798 cos'rmo APPARATUS Gale F. Nadeau-and Eugene B. Clea Rochester, N. Y., ors to Eastman Kodak Oompony, Rochester, N. Y., a corporation of New Jersey Application February 8,

1940, Serial No. 211,925

6 Claims. (01. 91-513 The presentinvention relates to coating apparatus of the type wherein'the coating solution is fed to the coating point by an applicator,

} or pick-up,.ro11 rotatably mounted in a hopper The application-of a dye, or subbing layer, to

, a photographic film is effectively carried out by the bead method of application, or by the direct application of a coating to the web to be coated from an applicator roll rotating partially submerged in a coating solution contained in a hopper, both of which procedures arewell known in the, art.

'cedures is substantially the same, and may constitute a hopper in which a constant level of the coating solution is maintained, and in which The apparatus used in both prohopper an applicator 'roll is rotatably mounted partially submerged in the solution. The two procedures differ primarily in the fact that in the bead method of application the applicator roll is slightly spaced from the guide roll for the web and merely feeds the solution to a bead maintained between the two rolls and through cedure the applicator roll directlycontacts the surface of the web to be coated and deposits the coating solution directly thereon. r

' In order to secure a subbed, or dyed, film and maintain a low concentration of explosive vapors .found necessary to circulate fairly large quantities of air about the hopper mouth during the coating and subbing of a photographic film. When a bead application of the two most serious defects arising from this disturbance is blotchy longitudinal lininess caused by the air blowing across the exposed periphery of the applicator roll. The second defect especially observed in gel subbing is a result of the removal from the sub of some of the lower boiling, and more active, solvents. 'The removal of these solvents leaves behind a higher concentration of water, and the sub accordingly loses strength, as its aflinity for the film is often referred to by those skilled in the art. It is quite common, therefore, to find a given sub layer 55 showing unsatisfactory stripping from a film or paper to which it has been applied with a given quantity or air flowing across the hopper mouth, whilethe same sub layer would show satisfactory stripping qualities when the quantity of air was reduced.

We have found that these two difiiculties can be greatly alleviated, or overcome, by reducing the exposure'oi the coating solution on the unsubmerged portion of the applicator. roll to air circulating over the .hopper mouth, and by raising the effective level of the solution in the hopper.

Therefore, one object of the present invention is to provide the hopper of a coating apparatus of the type described with means for protecting the major portion of the unsubmerged periphery of the applicator roll from exposure to air circulating around the mouth of said hopper.

Another object is to provide means of the typereferred to which raises the efiective level of the coating solution in the hopper, and thereby reduces the opportunity of separation of the solvents from the solution and the running back of the solution on the roll.

And another object is to provide a hopper in which the aforementioned means constitutes one or more arcuate shields suspended in the hopper concentric with, but spaced from, the an periphery of the applicator roll, said shields bewhich the web is passed, while in the other pro- And a further object is to provide shields as of the type mentioned which are adapted to extend substantially below the level or the coating solution in the hopper so that the level of-the solution rises somewhat, or is pumped. up into the narrow space between the shield and the o roll whereby the level or the solution is efiectively is being made, the disturbances caused by this air have been found to lead to'the non-uniform application of the solution being applied. One

of the application roll in accordance with the viscosity of the coating solution and the speed of the roll. I

And still another object is to provide means or the type referred to for reducing the loss of active solvents in, and the running back on the roll of, the coating solution which is simple in construction. easy to manufacture, and is ap pllcable to any existing hopper without necessitating any major alterations therein.

Briefly. the present invention comprises the suspension of one, or more, arcuate shields in Fig. 3 is a sectional view corresponding to Fig. the sub hopper in concentric and spaced relation 2, and showing the hopper equipped with a shield attempts to use a lower level of coating solution 5 cut invention,

in the hopper. For some time we have been Like reference characters r fer to correspondexperimenting with a. hopper in which the level ing Darts throughout the drawings. of the coating solution is maintained below the Referring now to the drawings, the hopper, m-

,bearings of the applicator roll in order to elimdicated generally at l0, may be of a well-known inate the use of packing for the bearings which type and comprise an elongated trough having tends to produce non-uniform motion of he a bottom wall ll, side walls I 2, top walls l3, app i at r l- The r la ively lar r a a of and a substantially semi-circular wall l4 conwet application roll exposed to the air in this necting said top walls as shown. The hopper instance results in bad lininess due to the fracmay be cast from metal with all of said walls tionation of the mixed solvents used in the usual being contiguous, as shown, so as to form a hol subbing or coloring solution. The use Of e low chamber, or chambers, I5 completely surhi lds cons i u ing he pre ent inven ion, thererounding the semi-circular wall l4, and through fore, is essential to the use of lower levels of hi h heating medium, uch as, hot water or Solution in the p steam, can be circulated by means of an inlet The se e r f e s ie ds in e use type is, pipe 11 connecting the two chambers, of the low level hopper arises from the fact that and outlet pipe l8, for the purpose of maintainwhen t h ppe shi ld s set clos to t e app ling the coating solution in the hopper at a given cator roll and extends below the level of the sotemperature as, and for the purpose, well known o the solution rises somewhat, or is pumped in the art. The reservoir 20, formed by the semiof the solution adjacent the roll is efiectively cator roll 2|, and the width of the open mouth raised. n other W it is possible by use of of the reservoir will be substantially greater than the low level hopper and shields to bring the the diameter of the roll 2| to permit its insertion level of the solution higher than the bearings and removal therefrom. Due to this diiference ifdesired without necessitating the use of packing in size the opening between the edges of the for said bearings. The desire to raise the level of mouth of the reservoir and the periphery of the the solution is twofold. First, the nearer the level roll, when the latter is in its operating position, of the coating solution to the coating point, the will be quite large, and willpermit air, necesless opportunity there is for the separation of sarily circulated over the mouth of the hopper, the solvents and run back of the solution on the to contact the roll rather freely at any point applicator roll. The second consideration has to above its point of submersion in the coating sodo with uniformity of application. It has been lution.

d method f application, to d v the applithe reservoir in any suitable manner so that a relatively fast, a disturbance in the bead proconnected to a suitable supply of coating soluduces a defect known as "lap lines. These lines tion, and the flow through which may be contake the form of small wave-like patterns across trolled in proportion to the solution coated so the width of the support and can always be elimas to maintain a substantially constant level'in inated by reducing the applicator roll speed. the reservoir. The applicator roll 21 may be ro- This defect, of course, is quite likely to be had tatably mounted in the hopper by having opposite in the use of the low. level hopper if it were not ends of the shaft 23 connected thereto rotatpossible to use a shield of the type constituting ably mounted in suitable bearings 24 passing the present invention which eliminates the nethrough the end walls 25 of the hopper. The cessity of packing for the bearings of the apapplicator roll is preferably mounted with only plicator roll which tends to hinder uniform rotathe lower portion of its periphery submerged in tion of said roll when driven at slow speeds. the coating solution, and with the upper portion The novel features that we consider characof its periphery extending through the mouth of teristic of our invention are set forth with parthe hopper to the outside thereof and adjacent ticularity in the appended claims. The invention to a web guiding roll 26, in the case of the bead itself, however, both as to its organization and method of application, over which a web W to .its method of operation, together with addition-3 go be coated is guided. The applicator roll 2| may al objects and advantages thereof, will best be be rotated in one direction by any suitable means, understood from the following description of a not shown, and in a counter direction to the rospecific embodiment when read in connection tation of the guiding roll 26, as indicated by the with the accompanying drawings in which, arrows, so as to feed a quantity of coating solu- Fig. 1 i a plan view of an open-mouth hopper tion to, and for the purpose of maintaining, the

constructed and mounted in the hopper in ace hopper and applicator roll combination cordance with a preferred embodiment of the heretofore described is well known and forms no present invention, and part of the present invention except insofar as it Fig. 2 is a sectional view. taken substantially cooperatesyigh the hereinafter described shields on line 22 of Fig. 1, and showing the hopper to produce the beneficial results hereinafter fully and applicator roll associated with a web gul'd-- set forth. Referring to the drawings it will be ing roll as customary in the bead method of-apnoted that with an arrangement of the type deplication. scribed-there is a relatively large opening at the found that provided I Y 30 and the periphery ofthe hopper on each side of the applicator roll, and extending down into the hopper to the level of the coating solution, into which air circulated over the mouth of thehopper. can pass and evaporate solvents from the thin coating of solut'on on the roll between the bead and the level-of the coating solution. In addition, in order to avoid packing the bearings of the applicator roll shaft it that the level mo, th of the the roll exposed to the air circulating around the mouth of the hopper and would increase the run back tendencies of the solution on the roll, both undesirable features.

The present invention which cuts down the undesirable exposure of the applicator roll to air circulating about the mouth of the hopper, and level of coating solution than heretofore found practical,

' be described. An arcuate shield 30 is suspended in the hopper ill on both sides of the applicator roll 2| in concentric relation with, and spaced from, the periphery of the roll. Each of these shields is slightly longer than the roll so that it overlaps said roll on either end, and each shield below the norof the coating solution in the hopper outside of the mouth of the hopper, see Fig. 2. These shields, as'will be noted, effectively prevent the air circulating about the mouth of the hopperirom entering the hopper and cone tacting that portion of the shields, so that evaporation of solvents from the coating solutionis greatly'reduced. these shields could be extended to a point closer to the head 21 than has beenillustrated, and thereby protect more of the periphery of the roll against exposure to the circulating air, we have the time of exposure of that portion of the roll beyond the end of the shield and the head, as shown, is not sufficient to effect an appreciable evaporation of the solvents contained in the solution. air circulating about the mouth of the hopper generally moving tangentially of great tendency for the same to oi the space between the rolland the shields, particularly in a counter direction to the rotation of the roll.

It will be appreciated that to act a shield against the exposure of the air circulating about the mouth of the hopper the shield need extend only to, or adjacent to, the level L of the coating solution in the hopper. However, we have found that by extending said shield below the level L of the solution the same serves. to effectively raise the level in the hopper, in addition to protecting the roll against expomerely as roll to the it will be noticed that a rather limited space is between the lower portion of the shield roll. When the roll direction of the arrow the pumped, up into the the roll in the dithe level L higher than the normal level -.L of the solution. it the solution at this newf-level with which the roll engages prior to moving point, or bead 21,.the effective level, or thatsub'merging that portion of the periphery of the roll leaving the hopper,

M, is rotated in the sure to the circulating air. Referring to Fig. 2,

. 3 is raised only adjacent the periphery of the roll and in a manner not aitecting the bearings of the roll shaft whereby it is not necessary bearings be packed. In addition, this rise in the effective level reduces the arc of the periphery. of the roll exposed with a thin coating of solution prior to reaching the coating point, thereby reducing the v of solvents from the of solution in the reservoir be kept below said 10 solution, an at the same time the tendency of bearings. However, as pointed out above, lowerthe solution to run back on the roll prior to ing of .the solution level inthe hopper would inreaching the coating point-is reduced.

crease the amount of thin coating of solutionon By referring to Fig. 2 it will be observed that the shield 30 on entering the coating solution acts just the opposite than does the other shield in that the level of the coating solution adjacent the roll at thispoint is lowered by virtue of rotation of the roll instead of being raised. Consequently, this shield. need only extend to the normal level L of the coating solution to act .in the sole capacity of protecting the periphery of the roll against exposure to the air circulating around the mouth of the hopper. However, by submerging both shields in the coa'ing solution the apparatus is ready for use regardless of which direction the applicator roll 2i is rotated in.- the side of the roll entering the coating solution is really necessary only when the bead method of application is being used, since in this instance all of the coating on the roll is not left in the bead but a part of it is carried back to the hopper. However, where the roll applies the coating solution to the web to be no appreciable amount of the point, on that portion of the roll point and the hopper in the direction of rotation of the roll is not so important, and only the one shield on the side of the roll approaching the coating point may be necessary. i It will be appreciated that the rise in the effective level of the coating solution will depend shield to the peripheryof the roll and the viscosity of the coating solution If a relatively thin coating solution pumps with a given spacing level for For this reason it is desirable to be able to adjust the spacing of the shield 30 relative to the roll, and the following means has been shown as one way of accomplishing this. Since both shields have the same type of mounting the description of one will suffice for both. Located on each of the top walls I hopper it are one or more guide tubes 35, the number and spacing of the same depending upon the length .of the shield 30 to be supported. threaded supporting pin 40 extends freely through each guide tube 35 and has one end extending transversely of mouth and engaging a threaded block end of the shield '30 and pinned to said block. A manually adjustable knob 31, gagement with theother end of said pin, has a shoulder 38 provided with a peripheral groove 39 with which a yoke member 4| bolted to the guide tube 35 engages to prevent axial movement of the knob when-turned. Thus when the knob is turned, since it cannot move axially, the thread- 75 ed supporting pin 40 and the shield carried f the coating solution I the side of the applicator roll The shield on to the hopper after passing shield and the roll, a more tion of the wheel, from exposure to ancirculat- Instead of having the roll protected by two ing around the mouth or said hopper, said means shields 30 as described, 'it will be appreciated, comprising an arcuate shield suspended from that there is no reason, other than .for the ease said hopper in concentric relation with said roll of assembly or the parts, why the two shields and spaced therefrom, said shield encircling that thereby constitute a single shield of tubular point where it leaves the solution and a point form. 'As clearly shown in Fig. 3 such a shield outside of said hopper within 30 of the coating could be made from a single tube 50 by cutting point.

a In a coating apparatus the combination with o n 2 applicator roll 2| extends at the coating point. n pg th hopper q t t contain a sup;

between the end walls of the hopper so that ably mounted in said hopper with a portion of he coating solution in the hopper can enter the s periphery dipping mto said solution and an nds of the u e to fi l he sp ce w en h other portion extending out of the mouth of said same and the roll A shield of this ype ca be opper, of means for protecting the greater part he h pper and could be suspended from the top point and the solution from exposure to air cirh n t the t eld 80 ha uppo from, one of said shields encircling that portion shi lds- As sh wn in i h u ar Shield tion of the roll between a point adjacent the could be suspended from the top wall l3 of the coating point n the point where it enters said hopper by having the ends of adjustable attachl t n,

ing bolts 52, passing through guide tubes 5| on 3. .In a coating apparatus the combination with the top walls 01' the hopper, adapted to threadan open-mouth hopper adapted to contain a supedly engage threaded blocks 53 attached t0 the pl f coating solution an applicator r011 11 wall of the tube adjacent" the slot therein. tatably'mounted i aid hopper with a portion described, for protecting the coating solution on 40 m point and th l tion fro ing solution due to such exposure. The shields in the hopper. By so raising the eifective level of an open-mum hem-mt adap tunity for separation of the solvents from the 55 t means for mta'fin oating solution and the run back of the solurectmnl of F for tion on the r ll. a of that portioirof the peripher are fully aware that many modifications thereof no circulating amuhd thqmout to be restricted except insofar as is by the prior art and by the spir t of the ap arcuate shield suspended from said pended claims. concentric relation with said Having thus described our invention, what we therefrom, Said shield adapted claim is new and desire to secure by Letters Pat- Point below the level the S01 ent of the United States is: per to a point outside of said In a oating apparatus the combination for di s the shield to nd with an ope -mouth hopper adapted to contain said mu in accordance with a supply of coating solution, an applicator 1 or the coating solution being used and rotatably mounted in said hopper with a portion 70f rotatiml 0f the rollof s p iphe y dipping into said solution and 5111 s apparatus e another portion extending out of the mouth of n n-m h h p er adap d said hopper, means for rotating said roll in one D y f ng solution. an ap i a rotfltflbly direction, or mean for protecting that portion mount in said hopper wit periphery dipping into said solution and another 4 portion extending out of the mouth of said hopper, of means for protecting the major part of the unsubmerged portion of the periphery of said roll from exposure to air circulating around the mouth of said hopper and for raising the eflective level of the solution in said hopper, said means comprising a pair of arcuate shields suspended from the hopper on opposite sides of said roll, and spaced therefrom, each of said shields adapted to extend from a point below the level of the solution in said hopper to a point outside or said hopper, and means for adjusting each of the shields to and from the periphery of said roll.

6. In a coating apparatus the vcombination with an openmouth hopper adapted to contain a sup-, ply or coating solution, an applicator roll rotat ably mounted in said hopper with a portion of its periphery dipping into said solution and another portion extending out of the mouth of said hopper, means for rotating said roll in one direction, of means for protecting the greater part of and adapted to be in concentric relation with said rollbut spaced therefrom, said shield adapted to extend from a point below the level of solution in said hopper to a point outside of said hopper, and manually adjustable means for moving said supporting member transversely of said hopper mouth for moving said shield to and from the periphery of said roll in accordance with the viscosity of the coating solution being used.

GALE F. NADEAU. v EUGENE R. CLEARMAN.