US3474758A - Multiple coating apparatus - Google Patents

Multiple coating apparatus Download PDF

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Publication number
US3474758A
US3474758A US680672A US3474758DA US3474758A US 3474758 A US3474758 A US 3474758A US 680672 A US680672 A US 680672A US 3474758D A US3474758D A US 3474758DA US 3474758 A US3474758 A US 3474758A
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US
United States
Prior art keywords
slot
coating
slide
hopper
layer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US680672A
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English (en)
Inventor
Theodore A Russell
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Eastman Kodak Co
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Eastman Kodak Co
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Filing date
Publication date
Application filed by Eastman Kodak Co filed Critical Eastman Kodak Co
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Publication of US3474758A publication Critical patent/US3474758A/en
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/74—Applying photosensitive compositions to the base; Drying processes therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C5/00—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work
    • B05C5/007—Slide-hopper coaters, i.e. apparatus in which the liquid or other fluent material flows freely on an inclined surface before contacting the work
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C9/00—Apparatus or plant for applying liquid or other fluent material to surfaces by means not covered by any preceding group, or in which the means of applying the liquid or other fluent material is not important
    • B05C9/06—Apparatus or plant for applying liquid or other fluent material to surfaces by means not covered by any preceding group, or in which the means of applying the liquid or other fluent material is not important for applying two different liquids or other fluent materials, or the same liquid or other fluent material twice, to the same side of the work

Definitions

  • the present invention relates to coating apparatus and particularly to an improved multi-slide coating hopper.
  • a multi-slide hopper is an apparatus that will simultaneously coat two or more liquids onto a solid support in such a way that the layers are not mixed and are individually of uniform thickness.
  • Such a hopper is disclosed in U.S. Patent 2,761,419 and the present invention relates to an improvement in such hoppers which overcomes a decided shortcoming of known hoppers of this type.
  • the conventional slide hopper performs its coating operation by metering a first coating liquid from a supply through a narrow distributing slot which distributes the liquid uniformly across the top of a downwardly inclined slide surface. This layer of liquid moves down the slide surface by gravity so as to supply an evened out and steady supply to a coating bead across and in contact with which the web to be coated is moved to pick up a layer of liquid therefrom.
  • a second liquid is supplied to, and distributed by, a second distributing slot which in turn directs a uniform layer of the liquid onto the top of a second slide surface so as to flow down to the coating bead, first alone on its own slide surface, and then onto the top of the layer of liquid issuing from the first distributing slot and then down to the coating bead in superposed relation with the layer of first coating liquid.
  • Subsequent liquids may be coated simultaneously by equipping the hopper with the appropriate number of distributing slots and slide surfaces.
  • these pencile lines can be caused by a blockage in the lowermost of two distributing slots, or in the slot where two layers of liquid ice come together in moving down the slides to the coating bead.
  • These pencil lines can be avoided either by removing the cause of the blockage in the distributing slots, i.e., taking out gelatin slugs or unusually large silver grains when silver halide solutions are being coated, etc., or by redesigning a part of the hopper so that the interruption of flow due to such a blockage does not result in a pencil lne.
  • the present invention is directed to an improved arrangement of the discharge slots in a multi-slide coating hopper to eliminate a newly discovered source of pencil lines when using such a coating hopper.
  • Patent 2,761,791 the materials flowing vertically upward must stop their upward motion before they start down the slides. Particles sometimes stop where they should make this turn and are held by the noted stagnant condition existing at this point.
  • the exit end of the slot(s) is designed or arranged to direct the flow of liquid therefrom downwardly of the slide at full, or near full, flow velocity. To this end the slots are arranged so that their exit ends are inclined in a range of to 145 inclination in relation to the slide surface onto which they exit.
  • This configuration which may also be used in conjunction with widened slot ends, such as described in U.S. Patent 3,005, 440, provides a desirable solution to the prior a-rt problem of pencil lines described above.
  • FIG. l is a sectional detail of a dual hopper constructed in accordance with a preferred embodiment of the present invention.
  • FIG. 2 is an enlarged sectional detail showing the exit end of the lowermost distributing slot enlarged on the down side of the slot in accordance with one embodiment of my invention
  • FIG. 3 is an enlarged sectional detail showing another embodiment wherein the upper end of the lowermost discharge slot is curved so that its exit end directs the flow of liquid therefrom downwardly of its associated slide at full or near full flow velocity;
  • FIG. 4 is an enlarged transverse sectional detail of a web coated with a conventional dual slide hopper and illustrating, in an exaggerated way, how undesired pencil lines might appear in the final product.
  • FIG. 1 my invention is shown on a conventional dual slide hopper of the type disclosed in U.S. Patent 2,761,419.
  • a constant discharge metering pump P into a cavity at a given rate through inlet 11 and from which it is forced through a narrow distributing slot 12 in the form of a ribbon and out onto a downwardly inclined slide surface 13 down which it flows by gravity in the form of a layer 14 to a point where it forms a coating bead B between the lip 1,5 of the slide surface 13 and a web W moved upwardly across and in contact with the bead by a supporting roll 16.
  • the second coating composition C2 is continuously pumped into a second cavity 17 at a given rate by another constant discharge metering pump P through inlet 18 and from which it is forced through a narrow distributing slot 19 in the form of a ribbon and out onto a second downwardly inclined slide surface 20.
  • This ribbon of the second coating composition in owing down the slide surface 20 under the influence of gravity, forms a smooth and uniformly thick layer 21.
  • the two slide surfaces 13 and 20 are coplanar, or substantially so, so that as the layer 21 of the second coating composition reaches the ribbon of the first coating composition issuing from slot 12, it flows up on top of the same and the two then flow together down slide surface 13 and into the coating bead B.
  • the relative thickness of the two layers of coating materials will depend upon the rate at which the individual coating uids are pumped to the cavities 10 and 17 by pumps P and P.
  • the slide hopper and the method of coating carried out by the use thereof described up to this point is shown in the above noted U.S. Patent 2,761,419, and the improvement therein which constitutes the present invention will now be described.
  • the purpose of the distributing slots 12 and 19 is to cause the issuance or extrusion of the liquid coating compositions in a uniform ribbon across the entire width of the hopper or the length of the distributing slots. Since the hopper may be as wide as 48 to 75 and the cavities 10 and 17 for the coating compositions do not extend the full length of the slots, but only over a limited length 0f the center portion thereof, these distributing slots must be quite narrow in order to do a satisfactory job of distributing the coating compositions throughout the full length of the slots.
  • the length and depth of these distributing slots may vary with the solutions to be coated, the uniformity in thickness required over the full length of the slot, and the flow rates to be used. At best they are very narrow, e,g. .009 or .010 inch. As pointed out above, pencil lines often appeared in the coated product made with slide hoppers.
  • FIG. 4 is a partial and greatly enlarged transverse cross-section of ya web coated with a dual slide hopper, it will be seen that the layer 14 of coating composition C1 directly engaging a web W has two indentation 30 running lengthwise of the web which are filled with the second coating solution for-ming layer 21. It will thus be appreciated that at the indentation 30 the thickness of layers 14 and 21 will be relatively different than at other portions of the web notwithstanding the fact that the overall physical thickness of the two layers at these particular points may be the same as at all other points across the web.
  • these pencil lines cannot be readily physically measured but will be visually apparent after drying or processing if one of the layers is a silver halide solution and the other is a clear gelatin solution as found in photographic film.
  • these pencil lines may occur by reason of a small obstruction in the distributing slot 12, e.g., a grain of silver in the silver halide solution or a slug of gelatin in a photographic emulsion, which causes an interruption in the flow pattern -moving out of slot 12 and onto the slide surface 13 or as the result of a particle or air bubble being caught and held at the edge of the exit of the slot, or in the first one-eighth inch of the associated slide, by reason of a stagnant condition resulting from the abrupt change in flow of the uid as it imerges from the slot and then moves down the slide under the force of gravity.
  • the present invention relates to a modification in the hopper design, where it has two or more slides, so as to enable coatings to be made free of pencil lines which result from the trapping of particles and/or bubbles at, or on the slide surface near the edge of the exilt end of the slide due to the abrupt change in direction of flow of the coating solution.
  • this modification in design consists in directing the exit end of the discharge slot 12 downwardly of its associated slide surface toward the coating bead rather than having it extend vertically and enter its slide surface at an acute angle as shown in the noted prior art.
  • the angle 0 should preferably be from to 145.
  • the inclined slot may also be modified according to the description of U.S. Patent 3,005,440.
  • the discharge slots may have their ends enlarged as shown at 23 in FIGURE 2.
  • U.S. Patent 3,005,440 For further details of this modification reference should be made to U.S. Patent 3,005,440.
  • the leaving end'of the slot 12' is curved, instead of straight, so that the ow of coating fluid emerges therefrom and onto the slide surface 13 at full, or near full, flow velocity. This will eliminate any stagnant condition which might result from an abrupt change of direction in the ow of fluid onto the slide surface and insure that any and all particles and/or bubbles emerging from the slot will pass on down the slide surface rather than being caught at this point and produce pencil lines in the nal coating.
  • a multiple-layer hopper for feeding a plurality of fluid coating solutions in superposed and distinct layer relationship to a coating bead from which they are simultaneously deposited in such strata relationship onto the surface of a web moving across and in contact with said coating bead, and comprising a multiple-layer slide hopper, a slide surface on said hopper inclined downwardly and terminating in a lip adjacent said coating bead; a plurality of narrow distributing slots, one for each coating composition, extending from the interior of said hopper and opening into said slide surface and through each of which a thin layer of coating composition is adapted to be discharged onto said slide surface, the lowermost of said distributing slots spaced from said lip and the remaining distributing slots spaced above the lowermost slot and each other to provide an uninterrupted slide portion below each slot over which the layer of coating solution discharged therefrom flows by gravity to form a smooth layer of uniform thickness before, in the case of all but the lowermost slot, it reaches the next lowest distributing slot and ows onto the top of, and along with, the layer of
  • a multiple-layer hopper according to claim 1 characterized by the fact that the portion of at least one of said lowermost of said slots approaching the slide surface is curved downwardly toward said lip and the discharge end thereof exits upon the slide portion immediately below it in a downward direction.
  • a multiple-layer hopper for feeding a plurality of fluid coating solutions in superposed and distinct layer relationship to a coating bead from which they are simultaneously deposited in such strata relationship onto the surface of a web moving across and in contact with said coating bead, and comprising a multiple-layer slide hopper, a slide surface on said hopper inclined downwardly and terminating in a lip adjacent said coating bead; a plurality of narrow distributing slots, one for each coating composition, extending from the interior of said hopper and opening into said slide surface and through each of which a thin layer of coating composition is adapted to be discharged onto said slide surface, the lowermost of said distributing slots spaced from said lip and the remainingdistributing slots spaced above the lowermost slot and each other to provide an uninterrupted slide portion below each slot over which the layer of coating solution discharged therefrom flows by gravity to form a smooth layer of uniform thickness before, in the case of all but the lowermost slot, it reaches the next lowest distributing slot and flows onto the top of, and along with, the layer of coating solution discharge
  • a multiple-layer hopper according to claim 3 characterized by thte fact that the discharge end of at least one of said lowermost of said slots is wider than the major portion of the slot and the enlargement in the slot being sudden and sufficiently great so as to produce a turbulence in the coating solution through the wider portion and thereby heal any interruption of ow that may occur as the result of a blockage in the narrow portion of the slot.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Coating Apparatus (AREA)
US680672A 1967-11-06 1967-11-06 Multiple coating apparatus Expired - Lifetime US3474758A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US68067267A 1967-11-06 1967-11-06

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US3474758A true US3474758A (en) 1969-10-28

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US680672A Expired - Lifetime US3474758A (en) 1967-11-06 1967-11-06 Multiple coating apparatus

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US (1) US3474758A (enExample)
DE (1) DE1806887A1 (enExample)
FR (1) FR1590857A (enExample)
GB (1) GB1256515A (enExample)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4143190A (en) * 1977-01-27 1979-03-06 Polaroid Corporation Method and apparatus for coating webs
US5332440A (en) * 1992-01-21 1994-07-26 E. I. Du Pont De Nemours And Company Coating lip geometry for slide bead coating
US5405442A (en) * 1992-03-24 1995-04-11 Eastman Kodak Company Liquid passage system for photographic coating devices
US20030124254A1 (en) * 2001-12-27 2003-07-03 Rexam Image Products, Inc. Wet on wet process for producing films
US20080075837A1 (en) * 2004-10-29 2008-03-27 Bower Christopher L Method of pattern coating

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2761791A (en) * 1955-02-23 1956-09-04 Eastman Kodak Co Method of multiple coating
US3005440A (en) * 1959-01-08 1961-10-24 Eastman Kodak Co Multiple coating apparatus

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2761791A (en) * 1955-02-23 1956-09-04 Eastman Kodak Co Method of multiple coating
US3005440A (en) * 1959-01-08 1961-10-24 Eastman Kodak Co Multiple coating apparatus

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4143190A (en) * 1977-01-27 1979-03-06 Polaroid Corporation Method and apparatus for coating webs
US5332440A (en) * 1992-01-21 1994-07-26 E. I. Du Pont De Nemours And Company Coating lip geometry for slide bead coating
US5405442A (en) * 1992-03-24 1995-04-11 Eastman Kodak Company Liquid passage system for photographic coating devices
US20030124254A1 (en) * 2001-12-27 2003-07-03 Rexam Image Products, Inc. Wet on wet process for producing films
US6824818B2 (en) 2001-12-27 2004-11-30 Soliant Llc Wet on wet process for producing films
US20080075837A1 (en) * 2004-10-29 2008-03-27 Bower Christopher L Method of pattern coating

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Publication number Publication date
GB1256515A (enExample) 1971-12-08
FR1590857A (enExample) 1970-04-20
DE1806887A1 (de) 1969-06-12

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