DE1806887A1 - Device for supplying liquid coating compounds - Google Patents

Description

int. CL:

B 05 c

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

German KL: 75 a, 20

OS) ÖÖ

Publication 1806 887

File number: P 18 06 887.6 Filing date: November 4, 1968 Date of publication: June 12, 1969

Exhibition priority: -

Union priority Date: Country:
File number:

November 6, 1967
V. St. v. America
680672

Designation: Device for supplying liquid coating compounds

Addition to: Removed from: Applicant: Eastman Kodak Company, Rochester, N.Y. (V. St. A.)

OO OO VO O 00

Representative: Wolff, Dr.-Ing. Walther; Bartels, Hans; Brandes, Dipl.-Chem. Dr. Jürgen; Held, Dr.-Ing. Martin; Patent attorneys, 7000 Stuttgart and 8000 Munich

Named inventor: Russell, Theodore Alton, Rochester, N. J. (V. St. A.)

Notification according to Art. 7, Paragraph 1, Paragraph 2, No. 1 d. Ges. V. 4.9.1967 (Federal Law Gazette I p. 960): -

© 5.69 909 824/263

l *> r4% / o * "- ^f A ^ U '33 / 94 7 Stuttgart I _x the 22.10.68

DR.-1N

7 STUTTGART-N, LANGE STRASS 51

Reg. No. 121 63 ^

Eastman Kodak Company, Rochester, New York State, United States of America

Device for supplying liquid coating compounds

The invention relates to a device for feeding several liquid coating compounds in individual layers lying on top of one another Layers to form a coating drop, from which the layers are applied simultaneously to the surface of a carrier be, the animal touches the coating drop and itself moved past this, with a multiple slide funnel, which has a slide surface that is inclined downward and in a lip j ends next to the coating drop as well as for each coating compound has a narrow, slit-shaped distribution channel, which opens into the sliding surface and extends into the interior of the funnel extends, the lowest of these channels at a distance from the lip and the rest "above the lowest and at a distance open from each other, so that below each channel mouth there is a section of the sliding surface free of interruptions, Via which the coating mass exiting from the assigned channel mouth as a result of gravity with the formation of a smooth, evenly thick layer flows.

In the known devices of this type, a certain amount of a first liquid coating compound per unit of time

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From a reservoir through a narrow ^{Verteilerkanal-:} gel el "-, tet, the coating composition de.r evenly distributed a downwardly inclined sliding surface on .the upper end. Under the action of gravity, the layer thus formed moves down on the sliding surface. Coating material is thereby supplied uniformly and steadily to the coating droplet, If two layers are to be applied to the carrier to be coated at the same time, the second liquid coating material is supplied to a second distribution channel and from this in the form of a uniform layer to the upper one Applied to the end of a second sliding surface, on which this layer flows downwards against the coating _{drop, initially alone and then on that layer 9} which is fed from the first distribution channel, so that the layers lying one above the other reach the coating drop together, '

It has been found, that these known devices are common lead to errors in the end product, which are long, running in the coating direction. Lines appear. These errors are not always during the coating process already recognizable, but often only become visible after the product has dried and / or developed, which for example in the event that it is a photographic product. Experiments have shown that these lines, which hereinafter referred to as pencil lines, result from long lines indicating a local lack of coating liquid when the same. exit. from. the .lower. distributor slot if a double sliding funnel is used. The layer thickness of the second coating liquid is thicker at the points of these lines, by so much that the entire thickness of the two layers "is in the area of the lines is the same as in the other, undisturbed areas, '' '' '

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These pencil lines can be created by an obstacle in the lowest of two distributor slots or in a slot in the two layers of liquid coating compounds as they move down the sliding surfaces towards the coating drop meet. The pencil lines: can be avoided by finding the cause of the blockage in the manifold slots eliminated, d. H. ßelatine balls or unusually large silver grains when using coating compositions with silver halides, or that part of the sliding funnel is removed redesigned in such a way that an interruption of the inflow as a result of such a block does not result in pencil lines. .

One known device attempts to solve the problem of pencil lines by widening the mouth of the distributor slots, at which two coating compounds come into contact with each other, to be solved, with the extension's so formed that in the coating mass flowing through the distribution channel due to a sudden change in flow velocity a turbulence is generated before exiting the manifold. This turbulence heals every pencil line which has been formed in the flow by a barrier in the narrow part of the channel, -hehe coating compound from the Distribution channel exits .. and reaches the sliding surface where it immediately comes into contact with a second layer of liquid coating material from a higher-lying sliding surface coming here flows downwards. With this known device, however, the 'creation of pencil lines cannot be completely can be prevented, as these can also be traced back to other causes. · ·

In removing particles, that may be pencil lines namely, it has been found that these particles and sometimes bubbles are often in a range of

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a few millimeters; Set the width of the sliding surface below the lowest of two adjacent sliding surfaces. Such particles or bubbles are easy to get rid of once you've discovered them, and they keep moving around down over the remaining section of the sliding surface, for example when set in motion again by a gentle push "These 'observations became the knowledge gained that in the upper part of the sliding surface there is an area in which the coating mass is almost stationary, and that it is unlikely .i, st that particles are in this Once the area has established itself, it will again be swept away by the liquid flowing around it. Furthermore, it is very true- it seems that such a particle is large enough to affect the flow in its vicinity · If sliding funnel are used whose distributor channels' run in the vertical direction upwards, the coating compound must, the flows up in the canal, come to a standstill before it begins, to flow down over the sliding surface · particles that are located in the coating compound, -stead therefore sometimes to a standstill, 'when they make the required change in the direction of movement should and will then, due to the lack of flow in the one directly adjacent to the mouth opening Zone held here ·. . :.

The object on which the invention is based is a device for supplying several liquid coating compounds in individual superimposed layers, to a coating drop should be designed in such a way that no so-called pencil lines can arise, based on the above-mentioned knowledge according to the invention achieved in that the channel mouth at least one of the lower channels is directed so that the emerging mass on the associated portion of the sliding surface under a

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obtains obtuse angle and its speed is a component ■ has downwards in the direction of the sliding surface,

_K The coating compound has at least one speed component during the exit from the distribution channel and already at the beginning of the movement over the sliding surface in the direction in which the coating compound moves on the sliding surface against the coating drop, so that entrained particles or bubbles do not move can still set in the mouth opening in the adjacent area of the sliding surface.

In detail, the training can be made so that at least one of the lower channels, preferably the lowest one, is curved towards the lip and with a downward direction in the ones immediately below the mouth opening Section of the sliding surface opens. If the direction of the distribution channel is chosen so that the coating compound emerging from it flows almost tangentially onto the sliding surface, then the The speed of the mass flowing out in the direction of the flow on the sliding surface is almost as great as the flow speed in the canal

The stocking angle that the channel at its mouth with the associated Forms portion of the sliding surface, is preferably "between about 95 ° and 145 °.

There is turbulence in the coating just before it emerges the same from the distribution channel also the formation of so-called Counteracting pencil lines, the end section can also be used of the channel opening into the sliding surface at an obtuse angle, and the transition to the expansion at least substantially stepped and the extension be chosen so large that in the flowing mass Turbulence arises,

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BAD OHJGlNAL

In the following the invention is illustrated with reference to the drawing Exemplary embodiments explained in detail. It show: ■■ -'.- "

Pig, 1 a section of an embodiment with two ver ' divider channels,

Pig, 2 is an enlarged section through which Muzzle opening of the distribution channel of a modified embodiment,

Pig »3 'a section corresponding to Figi 1 of a further embodiment \

Pig, k 'shows an enlarged cross-section through. a layer support with two lines of _{sight 9v} applied by means of known devices which have so-called pencil lines,

A double sliding funnel, which is designed in a known manner with the exception of the distribution channels, receives a first liquid coating compound C ₁ from a metering pump P which measures a constant amount per unit of time Speed and then arrives in a cavity 10, from which it is pressed in the form of a band through a narrow, slit-shaped distributor channel 12. The distributor channel 12 opens into a downwardly inclined sliding surface 13, onto which the channel 12 emerged "Coating route due to the force of gravity flows in the form of a layer 14 to a point where it forms a coating drop B between a lip 15 of the sliding surface 13 and a band W, which is past the coating drop B and in contact with it by means of a carrier roller 16 b 'is gone.

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A second coating material C ₂ is continuously pumped through an inlet 18 with a certain speed in a second cavity 17 _t of which is forced out of it in the form of a strip by a narrow "slit-shaped distribution passage 19 to a second, downwardly inclined sliding surface twentieth This band, consisting of the second sealing compound, forms a smooth and evenly thick layer 21t by flowing under the action of gravity on the sliding surface £ 0. The two sliding surfaces 13 and 20 'are in the same plane or at least almost in the same plane, so that the layer 21 consisting of the second coating compound leaves the first loading area when it reaches the strip emerging from the distribution channel 12; Stratification mass flows up onto this. The two layers 21 and 14 then flow, as also shown in FIG. The thickness of the two layers 21 and 14 depends on the speed at which the coating compounds are pumped into the cavities 10 b £ w, 17 ^{by means of the pumps P and P 1.} Since the sliding funnel and the method for coating it are known in this respect, further explanations can be delayed.

The task of the distribution channels 12 and 19 is to ensure the exit of the liquid coating masses in the form of a more uniform, spread over the entire width of the funnel or length of the _{slotted Λί} . . , ..,. extending .bands, _.,., ".s *" Ji j-shaped mouth grooves / to ensure. Since the width of the sliding funnel can be about 120 cm to 140 cm and the cavities 10 and 17 do not extend over the entire width of the distribution channels, but only over a central section, the distribution channels must be very narrow in order to distribute the coating material over the whole To ensure channel width. The width and height of the distribution channels can depend on the type of coating compound and the required uniformity

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the thickness over the entire width of the channel and the flow velocities used depend. Preferably, however, the distribution channels are designed to be very narrow, for example with a height from 0.23 to 0.26 mm. As mentioned above, the so-called occur Pencil lines often appear in products that have been coated with slide funnels.

Fig. 4 shows it schematically on the basis of a greatly enlarged shown cross-section the tape W, which has been coated by means of a previously known double sliding funnel. The layer 14 consisting of the coating compound C is located directly on the tape W and has two groove-like depressions 30, which run in Bjandlängsrichtung and with the second coating mass are filled, which forms the layer 21 lying on the layer 14 ·. It is obvious, that in the area of the depressions 30 the ratio of the thicknesses of the layers 14 and 21 is different than in the other areas of the Tape, although the total thickness of the two layers in the region of the depressions 30 is the same as in the other regions of the tape. ·· This means that these pencil lines cannot easily be measured, but become visible after drying or developing, if one of the layers is a silicon / overhalide mass and the other is a clear gelatin mass, as is the case with photographic films. As mentioned above, can these pencil lines through a small obstacle in the distribution channel 12, for example a silver grain in the silver shark ogenid mass or a gelatin ball in the. photographic emulsion, arise because such an obstacle is an interruption caused in the flow of the coming from the distribution channel 12 on the sliding surface 13 mass. The pin lines can but also come from a particle or an air bubble at the edge of the mouth of the distribution channel or in the approx 3 mm wide adjoining section of the same surface because of

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a lack of sufficient flow. The insufficient Flow arises from a sudden change in the flow of the coating that is being carried out.

_This must be done when the coating compound emerges from the distribution channel and then has to flow down the sliding surface under the action of gravity. In the case of a single layer exposed to air, a disturbance leading to a pencil line in the case of multiple layers would heal itself from the surface forces, which tend to reduce the total free surface to a minimum. If, however, the layer 21 consisting of the second sealing compound C ~ runs onto the first layer emerging from the distribution channel 12, the depressions 30 of the layer Ik are filled with the second coating compound, provided that the interfacial tension between the co-operating coating compounds C-, and Cp is small or zero. In this way a pencil line is formed, as shown in FIG. 4, because no healing force is active at the interface between the two layers conditional irregularity. .

By widening the distribution channels just before the mouth opening not all pencil lines can be eliminated as these are also caused by particles and / or air bubbles, which are held at the edge of the mouth of the distribution channel or in the adjacent section of the sliding surface, because here as a result of the abrupt change in the direction of flow of the coating compound after it exits the distribution channel an at least almost no-flow condition prevails »

In the embodiment shown in Fig. 1 "the inventive Device is d: ". E creation of such pencil lines

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this prevents the end section of the distributor channel 12 adjacent to the mouth opening from being inclined towards the coating drop B instead of running vertically upwards, as is the case with the previously known devices. The inclination of the channel 12 is chosen such _a that the angle 0 _S forming the channel with its associated sliding surface 13, is between 95 ° and 145 °, · The exiting from the manifold channel S ^ rom has by this inclination of the channel 12 a Speed component parallel to the sliding surface 13 towards the coating drop B. This velocity component prevents _s that particles and bubbles can lodge at the mouth opening of the distributor channel 12 or in the immediate vicinity on the sliding surface 13, ■

In order to prevent the creation of those pencil lines as well, which can be traced back to a blockage in the distribution channel, is in the modified embodiment shown in Pig, FIG the inclined manifold 12 in., its end portion 23; this creates turbulence in this area in the coating composition, ·. . .

In another embodiment shown in FIG. 3, the end section of the distribution channel 12 'is not guided in a straight line, but rather curved, but also towards the coating drop. The Bo.chi mass exiting from the distribution channel 12 'reaches the sliding surface 13' in the direction of the sliding surface. ^ Cbt almost equal to the flow speed in the channel 12 'isu; because the channel 12 'opens almost tangentially into the' sliding surface 13. Otherwise, this embodiment is designed in the same way as that according to FIG. 1, which is why those reference numbers which identify corresponding parts are provided with a prime and a repeated explanation of the structure of the device is dispensed with,

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The flow velocity in the direction of the sliding surface, which the coating compound emerging from channel 12 ', closes the creation of areas in which no or almost no no flow velocity is present, and sets ensure that any particles and / or bubbles coming out of the opening of the 'distribution channel 12' emerge over the sliding surface flow towards the coating drop and therefore none Can form pencil lines.

Of course, the inventive 'leadership of the Use distribution channels also for hoppers with more than two sliding surfaces (| and distribution channels »In such cases any or all of the distribution channels below a sliding surface. ' before or where two layers come into contact, be performed in the manner according to the invention.

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Claims (4)

Claims 1 »device for feeding _# are more liquid coating materials in individual superimposed layers to a coating beads from the transfer of the layers simultaneously to the surface of a substrate ,. which touches the coating drop and moves past it, with a multiple sliding funnel, which has a sliding surface that is inclined downwards and ends in a lip next to φ the coating drop, as well as a narrow, slit-shaped distribution channel for each coating compound, which into the sliding surface opens and extends into the interior of the funnel, the lowest of these channels at a distance from the lip and the others open above the lowest and at a distance from one another, so that below each channel opening there is a section of the sliding surface free of interruptions, via which the Coating compound emerging from the assigned channel mouth as a result of gravity flows to form a smooth, uniformly thick layer, characterized in that the channel mouth at least one of the lower channels (12, 12 ') is directed so that the emerging material (C,) to the assigned, ™ section (13 | 13 '). the sliding surface at an obtuse angle (Θ) and its speed has a component in the direction of the sliding surface (13, 13 ') downwards. 2. Apparatus according to claim Γ, characterized in that at least one of the lower channels (12 ·) is curved towards the lip (B) and ^{opens with a downward direction in the portion (13 r} ) of the sliding surface immediately below the mouth opening . Ö09824 / 0263 18068ο, - • 13 - 3. Apparatus according to claim 1 or 2, characterized in that the blunt winding (Θ), which the channel (12) at its mouth forms with the associated section (13) of the sliding surface, lies approximately between 95 ° and l45 °, 4. Device according to one of claims 1 to 3, characterized in that the end portion (23) of the channel (12) opening at an obtuse angle into the sliding surface (13) is widened and the transition to the widening is at least substantially step-like and formed the expansion is chosen so large that turbulence arises in the mass flowing through. 909824/0263 Blank page