SU372778A1 - ALL-UNION - Google Patents

Description

one

This invention relates to the field of the photochemical industry.

Devices for coating a moving substrate are known, comprising a hopper with an adjustable slot, from which a flat jet in the form of a curtain, bounded along the edges by pillars, flows out, while the bunker is provided with pipelines.

The proposed device of a similar purpose provides a more uniform coating, adjusting the thickness of the applied layer. This is achieved by the fact that the dispensing gr. Gel is located in the upper part of the bunker, the working surface of which is made inclined and ends with a spout ensuring the moaning of the emulsion coming from the gap in the form of a stable or freely falling curtain. The guide posts, adjustable in height relative to the moving substrate, are coupled to the drive. Under the bunker, the screen and drainage with a deflector changing the direction of the falling curtain is strengthened. The guide posts are attached at one end to the spout of the hopper and extend downward along the path of the substrate. The upper ends of the guide posts are located directly at the nozzle of the bunker, and the lower ends end above the film path, with the lower end of each rack having an elastic protrusion covering the surface of the substrate.

FIG. Figure 1 shows a hopper for applying photographic coatings to a substrate, a vertical section; on fng. 2 - upper part of the modified hopper, vertical section; in fig. 3 - bunker in axonometric projection, option; in fig. 4, 5 and 6 — Apparatus for coating a substrate; variants; in fig. 7 and 8 are axonometric projections of the side guides for a freely falling vertical curtain; in fig. 9 is a side guide with an air screen associated with a vacuum exhaust fan; in fig. 10 is a diagram of the arrangement of the free-falling curtain relative to the roller carrying the substrate; in fig. 11 - side guide, option; in fig. 12 is a processing line with a coating device.

A prefixed device provides for the application of liquid photographic coatings to a moving substrate by creating an emulsion curtain freely falling on this substrate. By changing the forces acting on the curtain, you can change its thickness; for example, under the force of gravity speed

the falling liquid increases, and the thickness of the curtain decreases proportionally.

If a free-falling curtain is initially generated so that it does not have turbulence, i.e., the flow rate is equal at all points along the curtain line, then these characteristics are maintained even at the points where the curtain becomes extremely thin. The layer of emulsion coating applied to the moving substrate by means of a freely falling curtain is everywhere equal in thickness. In order to obtain an equal flow rate over the entire width of the curtain, the means used to create the curtain must provide low kinetic energy of the fluid at the beginning of its free fall, i.e. possibly a lower speed when a free-falling curtain is formed (less than 20-10 cm / s ).

The velocity of the falling fluid at the lower end of the free-falling curtain, i.e., the velocity of the impact, is the sum of the initial outflow velocity imparted to the fluid, and CKfpOcTH, acquired during free fall, by the action of gravity. The velocity of a collision can be quite high as a result of an increase in the height of the free fall, and yet in the curtain the flow velocity is equal throughout its width. The veil is covered with destructive influences, like airflow, during free fall.

Since the free-falling curtain may be wider than the substrate to be coated, the trap velocity is equal. It is necessary only in the interaction between the substrate and the curtain. In addition, since a portion of the coated substrate located along the longitudinal edge can be trimmed or rejected (due to unevenness of the coating along the edges), the curtain should have the same flow rate mainly in the part where it interacts with the substrate.

The stability of a free-falling vertical curtain, i.e., continuous flow in any part of it, is achieved at a flow rate of liquid photographic emulsion equal to at least 0.5 cm per second per centimeter of curtain width. To achieve a very small thickness and a very high uniformity of the emulsion layer of the photographic coating, it is necessary that the ratio of the flow rate, measured in cubic centimeters per second per centimeter of curtain width, to the speed of movement of the substrate to be coated, measured in centimeters per second less than 0.015. ,

A device for applying liquid photographic emulsions to the surface of the substrate (see Fig. 1) includes a hopper / with a liquid photographic coating loaded into it through the opening 2. At the bottom of the bunker there is an extended dispensing slot 3, the width of which is adjusted by the eccentric 4. The bunker and the dispensing slot 3 are located across the substrate movement (see arrow L), i.e., tapes or sheets to be coated.

Racks 5 are provided for adjustable installation of the hopper, in addition, they are guides for the free-falling curtain 6 covering liquid. A collector 7 is placed under the bunker below the substrate to capture the overflowing liquid that can be returned to the bunker. A band 8 is fixed in the collector 7, facilitating the initial installation of a free-falling vertical curtain and reducing the formation of air bubbles in the covering emulsion, since this band prevents the covering emulsion from twisting as it enters the collection.

When the device is in operation, a liquid photographic coating, such as gelatin halide emulsion emulsion, is fed into the bunker at a speed of about 0.5 cm per second per centimeter of curtain width. To create a free-falling curtain 6, the covering liquid is not squeezed out under pressure (the top of the hopper is open), and under the action of gravity flows through the dispensing slot 3. In some cases, the dispensing slot is made conical in the direction of the inlet 2 to provide a uniform speed. flow, because the hopper is filled only on one side. By using a gravity-type bunker (supply under the force of gravity), a layer of fluid flowing through the dispensing slot is introduced into the curtain at a low speed, for example less than 10 cm / sec. As a result, a very stable solution curtain is formed, having a low viscosity and a low flow rate, which is required for the manufacture of photographic coatings.

To adjust the height of the free-falling vertical curtain, the bunker is mounted on the side racks 5. The adjustment mechanism is composed of a rail 9, reinforced from one end of the bunker, and gear 10 connected to it.

The bunker shown in FIG. 2, forms a freely falling curtain in a simpler way.

The photographic emulsion liquid is pumped at a constant speed, commensurate with a given coating thickness, which is required to be applied to a substrate moving at a given speed, through the coating zone into cavity 11 and then through a vertical, narrow slit 12 on a slippery surface 13 inclined downward The layer of fluid flowing out of the dispensing slot is uniform in thickness and flows down the slippery surface 13 under the action of gravity. Reaching the lower edge, or spout 14, slippery surface, it forms a freely falling curtain 6, uniform in thickness. In a bunker of this type, the speed of the layer before entering the curtain in the vertical direction is close to zero and, therefore, the amount of liquid at the point where the curtain has elapsed is minimal. AT

As a result, a free-falling curtain of a photographic liquid emulsion of optimal thickness is obtained, the layer being very uniform, and, in addition, the curtain remains stable despite the low viscosity of the covering emulsion and low flow rate. This is especially important when a surfactant is added to a photographic emulsion, since during the passage of the tupx layer over a slippery surface, it is possible for the surfactant to diffuse into the interface between the current fluid layers before they form a curtain. This reduces the surface tension of the free-falling vertical curtain, which further increases its stability.

FIG. Figure 3 shows the coating device in axonometric projection. The longitudinal edges of the free-falling curtain are covered by vertical side posts 5, which also limit the substrate (tape) 15, extending the cover. Racks facilitate the formation of a vertical curtain, prevent the “wrapping up of its edges, and thus ensure the uniformity of the curtain across its width. The curtain tends to become sprawled in places close to the edge guides, so if the guides are placed within the substrate, then the coating applied at the edges of the substrate is thicker than the coating applied to the main part of the substrate, and there are difficulties with the substance. To avoid this, either the edges of the coated substrate are cut, or the curtain is made wider than the substrate. A uniform coating of the substrate is obtained, and the liquid coating transferred through the edges of the substrate is collected in a collector (not shown) and returned to the hopper for reuse.

The coating device shown in FIG. 4 to 5, contains a sliding-type hopper, as in FIG. 2. Liquid photographic emulsion is pumped at a constant speed into the cavity // and then through the vertical elongated dispensing slot 12 onto the inclined slippery surface 13. The layer of liquid flowing out of the slit 12 is uniform in thickness and wider. than the substrate to be coated. The slip surface 13 is located at an angle of approximately 15 ° to the horizontal and ends with a spout 14 having a radius of about 3.5 cm. The bottom surface of the spout is beveled at an angle of 30 ° to the horizontal surface. A free-vertical vertical curtain 6 communicates with a continuous belt 15, which envelopes the support roller 16, which feeds the tape at a constant speed into the coating area.

The free-falling curtain 6 is somewhat stretched around the tape 15, and the tape stretched around the roller to prevent liquid from getting on the roller. The height of the free falling curtain 6 may

adjusted by means of support posts similar to those of stands 5. Two small brush-shaped guides 17 of small diameter, installed vertically at the edges of the nozzle 14, restrict the freely falling curtain 6. The lower ends of the guides, located below the edge of the tape 15, pass into collectors 7, which There are EMULSION flowing down from the edges of the tape into collection 18, placed

in front of the roller 16. P1z collector 18, the liquid may be stored in a hopper for reuse.

The guides 17 may be located within the width of the layer, the one along the skopzhnoy surface, or at an equal distance from its longitudinal edges.

Under the bunker (see Fig. 4), a curved air screen 19 is fastened, which fits close to the plane of the belt 15, extends below the floor. The height of the hopper /, as well as the length or position of the airfoil screens 19 relative to the surface of the tape, can be adjusted. Air screens 19 protect the free-falling curtain from airflows and help remove airborne dust from the surface of the tape 15 in front of the coating area. The screens give the thickness or stability of the air barrier on the surface of the substrate through which the free-falling curtain must penetrate.

A curtain deflector (deflector) 20 (see Fig. 4) is installed between the side rails 17 at their lower end. It can turn and, intercepting

free falling curtain 6, send it to collection 18.

The device works as follows. The covering liquid is pumped by a gear-driven pump into the cavity // at a speed corresponding to the thickness of the layer of liquid that covers the surface of the belt 15. The liquid passes through an elongated narrow dispensing slot 12 and falls on the slippery surface 13. Under the action of gravity, the liquid flows in a uniform layer, at low speed, bends around the nose 14 and forms a freely falling curtain 6, uniform in thickness with a low and uniform speed at all points of the transverse

section. The free-falling curtain 6 flows into the collector 18 with the help of the deflector 20 until a stable curtain is installed and the tape 15 to be coated will not move at the required speed.

Then, the deflector 20, turning, exits the path of the falling curtain, which falls on the tape 15 and forms a thin even layer of fluid on it. If the liquid flowing from the edges of the substrate is not used again, side-bbie guides, as shown in FIG. 7 and 8. The lower end of the leg 21 of each side guide / 7 is attached to the brush 22, the leg 21 being approximately

at a distance of 0.3--6, bc and above the surface 7 of the tape 15 to be coated, and the bristle pile is 1.25 cm lower than the leg, so that the villi can slide along the surface of the tape. Due to this, the curtain 6 can have the same width as the substrate to be coated, 5 the covering liquid does not overflow the edges of the substrate, and the roller 16 can be made equal to or longer than the substrate and use one long roller to cover several tapes. The tape may have uncoated transverse bands when using additional side guides for curtains, each of which is already tape. The lateral guide 17 in the form of a rod 15 of small diameter, for example, stainless steel, may have an axial groove 23 in the leg 21, in which a strip 24 of flexible elastic material, such as a photographic film or stainless steel-20, is installed, resilient and flexible. The strips 24 slide along the surface to be coated and nakloieny to the edges of the tape 15, whereby the accumulation of covering liquid at the edges of the curtain 6 are discarded. The lateral directions of S-25 P1 17 can be positioned so that the coating is applied along the edges of the tape or in any places within the tape. The guides facilitate a more even distribution of the coatings, thus facilitating the appearance of the ribbon. To adjust the guides 17 in height, the bunker is fitted with a lid 25 in which there is a clamping pin 26. The pin fixes the side guides 17 in a predetermined 35 position relative to the roller 16. With the help of the head 27 it is possible to rotate the guide to change the slip angle of the strip 24 relative to the belt 15 The airglass screen 19 (see Fig. 9) can40 be straight, provided with an exhaust manifold 28 located adjacent to the tape to be coated and connected to a vacuum pump (not shown). Due to this, the free falling curtain is protected 45 from airflows that violate its stability, and, in addition, some air dust captured by the tape 15 is drawn from its surface before it reaches the free falling process 6. Side. 50, the guides 17 are provided with a sliding strip 24. In some cases (see Fig. 11), hollow guides 17 are fitted with an axial groove along the side closest to the curtain 55. Inside the hollow side guide, along its axis, passes a porous tube 29 into which a neutral liquid is pressed from above, for example a clean solution of jedatin, which is forced out of the axial grooves into the side guides. 17. Although it is preferable to coat the tape in a position where it is supported, Hanpiij / iep, on the roller 16, but the coatings should be applied using the device shown 65 8 in FIG. 12. This device has a sliding bunker /, which forms between the side guides 17 a freely falling curtain 6 wider than the tape 15 to be coated, and a collection 18 of a covering liquid lepturing. The part of the tape 15 passing through the free-falling curtain 6 is supplied with tension (in order to prevent vibration) to the coating area. The side guides, like any blowing screen, use any. Arrangements for feeding the tape should preferably be adjusted so that the speed of the tape as it passes through the free-falling curtain can vary according to the requirements of the coating. For satisfactory coating of the tape (see Fig. 10) the free-falling the curtain can be directed to the roller axis or shifted from the axis to the right or to the left. To increase the speed of the substrate and at the same time get good results when applying the coating, it is advisable to use means to reduce the thickness of the boundary layer of air at the surface of the substrate immediately before the substrate passes through a freely falling vertical curtain. The air barrier varies with the surface characteristics of the substrate, but it has a larger value with coarse surfaces than with smooth ones. for example, on a photographic film basis, the air barrier is smaller than on photographic paper. Air barrier is increased at high speeds of movement of the substrate, the subject of the invention 1. A device for coating a substrate containing a hopper with a dispensing slot for draining the emulsion with a free curtain that is limited in width by side rails to a substrate moving along the transporting node, characterized in that , for the purpose of a more uniform coating and the possibility of adjusting the thickness of the applied layer, the dispensing slot is brought into the upper part of the bunker, the working surface of which is made inclined and terminated A spout provides drip of the incoming emulsion in the form of a stable falling curtain, while the guide posts, adjustable in height relative to the moving substrate, are connected to the drive, 2. The device according to claim 1, characterized in that the guide posts attached at one end to the nozzle of the bunker and extending downward along the trajectory of the substrate, 3. The device according to claim I, characterized in that the upper ends of the guide posts are located directly at the nozzle of the bunker, and the lower ends terminate above the trajectory of movement Film, with the lower end of each rack has an elastic protrusion, scour the surface of the substrate. 4. The device according to claim 1, characterized in that it is reinforced under the bunker, at least. one height-adjustable screen and drain with a baffle that changes the direction of the falling curtain.

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