MXPA97005936A

MXPA97005936A - Method and apparatus for applying flu thin coatings

Info

Publication number: MXPA97005936A
Application number: MXPA/A/1997/005936A
Authority: MX
Inventors: R Kessel Carl; K Leonard William; C Melancon Kurt
Original assignee: Minnesota Mining And Manufacturing Company
Priority date: 1995-02-02
Filing date: 1997-08-04
Publication date: 1998-07-03

Abstract

The present invention relates to a method for coating a substrate with a layer, characterized in that it comprises the steps of: moving the substrate along a path through a coating station, forming a composite layer comprising at least a coating fluid and at least one carrier fluid having a formulation different from that of each coating fluid, wherein the carrier fluid comprises a liquid at the ambient condition in the coating station, flowing the carrier fluid at a rate which, by itself, is sufficient to form a fluid bridge that flows continuously from the composite layer to the substrate by the coating width, where the carrier fluid is continuous, contacting the substrate with the composite layer flowing to interpose the coating layer between the substrate and the carrier fluid and remove the carrier fluid while leaving the coating fluid deposited on the substrate as a coating layer, wherein none of the components of the carrier fluid is part of the coating and at least a portion of all of any components of the carrier fluid are removed, thereby allowing the carrier fluid to act as a type of carrier. transfer device

Description

METHOD AND APPARATUS TO APPLY LUBRICATED FLUID COATINGS Technical Field The present invention relates to coatings. More particularly, the present invention relates to the preparation and application of thin and ultrathin coatings.

Background of the Invention Coating is a process of replacing the gas that contacts a substrate, usually a solid surface such as a continuous coil or roll, by a fluid layer. Sometimes, multiple layers of a coating are applied on top of each other. After the deposition of a coating, the same may remain fluid such as in the application of a lubricating oil to a metal in a processing of a coil or continuous metal roll or in the application of chemical reagents to activate or chemically transform a surface of the metal. substrate Alternatively, the coating may be dried if the R * f.25414 itself contains a volatile fluid to leave behind a solid coating such as a paint, or it may be cured or otherwise solidified to a functional coating such as a release coating. to which a pressure sensitive adhesive will not aggressively adhere. The methods for applying coatings are described in Cohen, E.D. and Gutoff, EB, Modern Coa ting and Drying Technology, VCH Editors, New York 1992 and Satas, D., Web Processing and Converting Technology and Equipment, Van Vorstrand Reinhold Publishing Co., New York 1984. It is desirable and necessary in many situations coating ultra-thin layers which are not more than 5 microns thick. Of the known coating methods for applying continuous fluid coatings (such as roller, curtain, slot, pneumatic or air knife, and gravure coating) different from aqueous expansion techniques, none can apply coatings thicknesses wet below about 0.1 micron. To achieve final, lower dry thicknesses, the coatings should be diluted with a solvent that can be removed by evaporation to leave the desired coating below about 0.1 micron. This increases costs by adding the cost of the diluent, the cost of preparing the diluted coating fluid, and the cost of removing the diluent (such as by drying). Also, the necessary solvent is often dangerous for the environment and for manufacturing personnel. The batch methods for applying the ultrathin coatings molecule by molecule or drop by drop include condensation from a vapor phase and the electroorbidity process described in U.S. Pat. No. 4,748,043. However, few fluid coatings of commercial interest can be successfully vaporized, and the electrobraiding process is limited to a narrow range of viscosity and the electrical properties of the coating fluid. For thicknesses greater than 0.1 microns, multiple roller coaters or transfer rolls are used. Typical commercial equipment includes the five-roll coater sold by Bachofen & Meier Ag, from Bulach, Germany, and others. This style of coater is expensive in its purchase and maintenance because of its multiple drive rolls. Any defect in the surface of the rollers usually produces a repetition defect in the coating. Additionally, these coaters have not successfully applied wet coatings in the range of 0.005 to 0.1 mire. The aqueous or water expansion techniques were first based on the Lang uir-Blodgett method of producing and depositing monomolecular films as described by Blodgett in the Journal of the American Chemical Society (VoL 57, 1007, 1935). This method involves emptying or molding a dilute solvent solution of an organic molecule formed from a film on an inactive or stagnant aqueous surface. The solution is sprayed to form a thin film over the water-air interface. The solvent is evaporated leaving behind a monolayer of the film-forming molecules. The film is then deposited on the surface of a substrate by passing the substrate through the surface of the water on which the film of the monomolecular layer is floating. The U.S. Patent No. 4, 093,757 describes the formation of a continuous monomolecular deposit on a continuous substrate. Japanese Patent Application 63-327260 describes an improvement of Langmuir-Blodgett monomolecular technology wherein films larger than the thickness of the monomolecular layer are deposited on a continuous substrate to form an ultra-thin film coating at thicknesses of 0.005 to 5. mieras Although the technique of expanding the aqueous surface coats useful coatings on the substrates, it requires that the coating fluid be sprayed or spread spontaneously and rapidly over the water-air interface. To achieve this for many coating formulations, additional solvents and surface active agents must be found and added. Additionally, the maximum coating speed is limited by the spraying or diffusion rate. Also, the speed of coating the substrate is limited by other problems. It was reported that at modest speeds of 10 to 50 m / minute, air bubbles tend to be trapped between the film and the substrate. The techniques of aqueous expansion are based on collecting the coating from a pond of inactive water by passing the substrate a. through the surface of the water or by contacting the substrate with the surface of the water. Frequently, evaporation of the solvent must occur to create a solid or nearly solid surface film to allow direct transfer of the coating to the substrate. The surface of the pond is also subject to contamination that may increase over time, degrading the quality of the coating. The technique of water expansion is not known to be useful with miscible coating fluids and constituents of water soluble or dispersible coatings.

Brief Description of the Invention The apparatus and method of this invention covers ultra-thin liquid films on substrates. The invention includes moving the substrate along a path through a coating station, forming a plurality of fluid layers that are flowing, and flowing the layers in contact with each other to form a composite layer. The composite layer includes a coating fluid and a carrier fluid. The composite layer flows at a rate that is high enough to form a fluid bridge that flows continuously from the composite layer to the surface of the substrate for coating along the width. The composite layer that is flowing makes contact with the substrate to interpose the coating layer between the substrate and the carrier fluid. The carrier fluid is at least partially mechanically removed while leaving the coating fluid on the substrate as a coating layer. Coatings with wet gauges that exceed the ultrathin range can also be applied using this invention. The irascible and immiscible combinations of the carrier and coating fluids can be used in the composite layer.

The substrate passes through the coating station at speeds up to 2000 m / minute. The forming step may use a slide coater, curtain coater, extrusion coater, slot coater, blade coater, jet coater, roll coater, or other coaters, any of which are described in Cohen and Gutoff. The carrier fluid can be removed by scraping, suction, drainage by gravity, blowing, centrifugal removal, evaporation, using electric or magnetic fields, solidification or gelling of the coating or carrier followed by mechanical removal, absorption, or the combination of any of these methods. Additionally, the composite layer can be deposited on the transfer surface, such as a roller or a band, before being placed in contact with the substrate. The carrier fluid can be removed from the transfer surface and so that only the coating fluid is transferred to the substrate from the transfer surface.

Brief Description of the Drawings Figure 1 is a schematic view of a sliding curtain coating apparatus according to the present invention. Figure 2 is a schematic view of a jet coating apparatus according to another embodiment of the present invention. Figure 3 is a schematic view of a known slotted die coating apparatus. Figure 4 is a schematic view of a simplified curtain coating apparatus according to another embodiment of the present invention. Figure 5 is a schematic view of another embodiment of the present invention, utilizing a transfer roll wherein the carrier fluid is removed prior to the transfer of the coating fluid to the continuous roll or coil. Figure 6 is a schematic view of another embodiment of the present invention, which utilizes a transfer roller to transport the carrier and coating fluids to the continuous coil or roll.

Figure 7 is a schematic view of another embodiment of the present invention using a roller device on a blade, combined with a coating fluid matrix applicator.

Detailed description of the invention In this invention, a fluid stream of composite layer, which is flowing, of the carrier fluid and the coating fluid, is created and deposited on the surface of a substrate such as a coil or continuous roll. Deposition occurs when the continuous coil or roll is moved through the coating station such that the first fluid layer makes contact with the surface of the coil or continuous roll with the carrier fluid at the interface with the air above. the coil or continuous roll, and the coating fluid between the continuous coil and roll and the carrier fluid. The carrier fluid is removed to leave a layer of thin or ultra-thin coating fluid. The substrate can be any substrate such as a continuous roll or coil, discrete sheets or parts of rigid pieces, or an array of parts or parts transported through the coating station. The coating fluid can be coated at average thicknesses that are ultra-thin, ranging from 0.005 to 5 microns. Additionally, the fluids may be coated on substrates at thicknesses greater than the ultrathin range, which includes 100 microns or more.

Figure 1 shows a coating station having an apparatus for coating at speeds of 1 to 2000 m / minute. A coating matrix 10, shown as a photographic sliding curtain coater, has a cavity 12. The internal cavity 12 is connected to a tank 14 by a pressure metering pump 16 through a filter 18 and a bubble trap 20. Matrix 10 also has an internal cavity 22 which is connected to a tank 24 sealed in vacuum by a precision metering pump 26 through a surge tank or chamber 27, a filter 28, and a flow meter 29 A coating station is located near the die 10. A continuous roll or coil 32 passes through the coating station and until the die 10 has been passed, which is mounted transverse to the continuous roll or coil. The coating fluid 34 is pumped at a precisely controlled rate from the tank 14 by the precision metering pump 16 through the filter 18 and the bubble trap 20 to the internal cavity 12 of the cover matrix 10. The fluid carrier 36 is pumped at a controlled rate from the tank 24 by the metering pump 26 through the surge tank or tank 27, the filter 28, and the flow meter 29 to the internal cavity 22 of the cover matrix 10. carrier fluid is continuously added to the vacuum tank 24 through a flow control valve 23 and the flow meter 25 from a source (not shown). Tank 24 is connected to a vacuum source which is also not shown. For ultrathin coatings, the flow rate of the carrier fluid is much higher than that of the coating fluid. The internal cavities 12 and 22 distribute the coating fluid 34 and the carrier fluid 36 across the width of the matrix 10 and the faces 38, 40 of the matrix through the distribution slots 42, 44. The composite layer is formed by dosing continuously the respective fluids through the respective holes of the slots. The coating flap 34 flows on the upper part of the carrier fluid 36 at the outlet of the slot 44, and then flows on the upper part of the carrier fluid, in face-to-face contact, descending on the face 40 of the inclined array until the edge 46 of the matrix. From the edge 46, the film of the composite layer falls on a curtain 48 under the influence of gravity to contact the continuous roll or coil 32. The continuous coil or roll 32 is moved through the coating station and until the matrix 10 has been passed, so that when the multi-layered curtain 48 makes contact with the continuous coil or roll 32, the coating fluid is adjacent to the surface of the coil or continuous roll and is interposed between the coil or continuous roll and the carrier fluid. The coating fluid 34 makes contact with the continuous coil or roll. At the point of contact, a layer composed of the coating fluid and the carrier fluid has been applied to the continuous coil or roll. The composite layer flows at a rate that is high enough to form a bridge of uninterrupted, flowing fluid from the composite layer from the edge 46 of the die to the surface of the coil or continuous roll for coating of the width. The flow rate of the coating fluid alone does not need to be sufficient to form a fluid bridge that is flowing continuously. Regardless of whether the coating fluid is continuous, the carrier fluid must be continuous. The fluid bridge has two different fluid-gas interfaces: the fluid-air interface of the coating and the fluid-air interface of the carrier. Gases other than air can be used as long as they do not interfere with the coating process. The carrier fluid is a different composition that differs from the coating fluid. The carrier fluid functions to form a bridge between the matrix and the continuous coil or coil on which the coating fluid can travel to transport the coating fluid to the continuous coil or roll and to facilitate the creation of a thin layer of fluid from the coil. coating before the coating fluid makes contact with the continuous roll or coil. It may contain components that diffuse into the coating fluid or solid materials that by some mechanism are left on the coating fluid after the carrier fluid has been removed from the coil or continuous roll. The carrier fluid can be tap water or other fluids. The properties of the coating fluid and the carrier fluid cause the coating fluid flowing over the carrier fluid to form a continuous surface film, where desired, before reaching the continuous roll or coil. After the carrier fluid transports the coating fluid to the continuous coil or roll, the carrier fluid is removed. It is not necessary to remove the entire carrier fluid since it does not alter the desired characteristics of the coil or continuous roll coated. To achieve a good uniformity of coating on the continuous roll or coil, the flow velocity of the carrier fluid, the height "h" of the curtain, and the shock angle "a" of the curtain with the continuous coil or roll, are selected and adjusted when the speed of the roll or continuous roll is changed. The height "h" of the curtain is the distance between the edge 46 of the matrix and the continuous coil or roll 32 along the path of the curtain of the carrier fluid 48. This path need not be vertical. Under the influence of surface tension forces, electrostatic forces, viscous tensile forces, or magnetic forces, the path can be curved or at an almost horizontal angle, especially when the gap from the matrix to the continuous coil or roll is little. At very low speeds, it is often necessary to use a small curtain height (less than 1 cm), a near zero shock angle, and a minimum carrier fluid flow rate, to maintain a curtain 48 free of disturbance, continuous, between the edge 46 and the continuous roll or coil 32. The curtain 48 must make contact with the continuous roll or coil so that the coating fluid assumes the speed of the continuous roll or coil, and the coating fluid is acquired by and transported in the company of the continuous coil or roll. The flow velocity of the carrier fluid, the shock angles and the excessively large shock velocities can cause instability of the fluid bridge when it contacts the continuous coil or roll. This can alter the coating, or drag or emulsify the coating fluid in the carrier fluid. The removal of all or a portion of the carrier fluid from the continuous roll or roll 32 without objectionable removal of the coating fluid is possible if at least one of the conditions of the following physical and chemical properties is satisfied: (a) the carrier fluid is substantially more volatile than the coating fluid and can be evaporated leaving the coating below: (b) the carrier fluid has a substantially lower viscosity than the coating fluid; (c) the carrier fluid does not wet the coil or continuous roll coated with the coating fluid; (d) the coating fluid preferably reacts with or is absorbed by the substrate; (e) Either the coating fluid or the carrier fluid is gelled or solidified in the. coating station; and (f) the carrier fluid can be absorbed and removed by contacting it with an absorbent medium. If the carrier fluid is (g) immiscible with the coating fluid, the removal of the carrier fluid is often easier. A number of alternative, mechanical removal methods of at least some portion of the carrier fluid are possible. If conditions (b), (c), or (d) are satisfied, at slow continuous coil or roll speeds most carrier fluid can be drained under the influence of gravity toward a receptacle 50 while the coating remains on and is carried apart with the coil or continuous roll. Gravity drainage is especially effective at low speeds if conditions (b), (c), and (g) are satisfied. At higher speeds, a gas scraping nozzle, such as a scraping nozzle 54 by means of air, as shown in Figure 1, may supplement gravity drainage. A jet of gas 52 exits from the nozzle 54 creating a pressure and shear to force the carrier fluid out of the continuous coil or roll. At high speeds, the carrier fluid can also be removed by centrifugal force when the coil or continuous roll rapidly changes direction when it rotates around a small diameter roller. Surprisingly, especially when the coating fluid on the continuous coil or roll is of a thickness of less than 10 microns, and condition (b) is satisfied, the mechanical scraping devices (not shown), such as the blades or blades, they can remove most of the carrier fluid leaving most, often all, of the coating fluid on the coil or continuous roll.

In one example, the coating fluid is deposited as a layer at least 100 times thinner than the carrier fluid; the coating layer has a viscosity at least ten times higher than the carrier layer; the coating fluid has a vapor pressure less than half that of the carrier layer, the coating layer has interfacial properties such that it does not dehumidify from the continuous coil or roll while traveling through the coating station; the carrier fluid has interfacial properties such that it does not dehumidify from the wet continuous coil or roll of the coating fluid; and the interfacial tension between the carrier fluid and the coating fluid is greater than 1 dyne / cm. Another unexpected feature of this invention is that if the carrier and coating fluids are immiscible and the viscosity of the coating fluid is greater than that of the carrier fluid, the flow of the carrier fluid may be allowed to become turbulent. Previously, it has always been taught that for the simultaneous non-mixed application of multiple fluid layers to a continuous coil or roll, both layers must be maintained in laminar flow in their respective slots 42 and 44, and in downflow on the face 40 of matrix. The downward flow on an inclined plane is transient if the Reynolds Number, Re, is greater than 1000 and is laminar if the number is less than 1000. For the downward flow on an inclined plane of a fluid that is thinning without shearing, Newtonian , the Reynolds Number is given by Re = 4G / m where G is the mass flow velocity per unit width of the inclined plane and m is the viscosity of the fluid. For flow in a slot, the Reynolds Number must be kept below 1400 for it to remain laminar. For slots 42, 44, the Reynolds number is defined by the equation Re = G / m. Yet another unexpected feature is that thin coatings can be obtained from miscible carrier and coating fluids. In this case, the mechanical removal of at least some portion of the carrier fluid is produced by drainage or by blowing, removing it with the scraping nozzle 54 that uses a gas. The coating fluid 34 is dosed at a controlled volumetric flow rate to the matrix 10 by the metering pump 16. The average thickness of the wet coating on the continuous coil 32 will be approximately equal to the volume of the coating fluid supplied by the coating fluid. unit of time, divided by the surface area of the coil or continuous roll on which it is sprayed. When a continuous roll or roll is coated, this area will be equal to the coated width of the continuous roll or coil, multiplied by the speed of the roll or continuous roll. This makes possible an easy adjustment of the deposition speed of the applied coating. The. it can be changed proportionally, by changing the pumping speed of the coating or inversely proportional by changing the speed of the coil or continuous roll. If the speed of the continuous coil or roll varies with time, the deposited coating can be kept constant by varying the flow rate of the coating proportionally with respect to the speed of the continuous coil or roll. Figure 2 shows an alternative coating matrix, useful for the coating at variable speeds and preferably above 200 m / minute. The matrix 60 is a multi-layer jet coater. The die 60 ejects a free flowing fluid jet 62 from the die slot 64, which receives the carrier fluid 36 from the cavity 66. The coating fluid 34 exits from a cavity 68 and a slot 70, and it slides along a tilted die face 72 until it lies on the jet of the carrier fluid 36 emerging from the slot 64. The composite jet 62 of two layers is formed at the outlet of the slot 64.

A jet coater creates a free-flowing jet of fluid 62, which leaves the slot 64 of the die at a high enough velocity to form the jet 62 without the aid of gravity. In contrast, curtain coaters use gravity to allow curtain 48 to break freely from edge 46 of the coating matrix. With a jet coater, the bridge or jet 62 of the carrier fluid can be created horizontally or vertically upwards. Jet coaters have been used in the coating industry to apply only single coats and more commonly to apply a jet or coating flow to a continuous roll or coil prior to dosing by a roll recess or a coater sheet. blades or blades, as shown in brochure # 23-CM "Black Clawson Converting Machinery and Systems" p.4, by the Black Clawson Company of New York, New York. Jet coaters have not been used for the application of simultaneous multiple layers of fluids, to produce multiple layers of fluid on a continuous coil or roll. Jet coaters, described in U.S. Patent Application. Serial No. 08 / 382,963, entitled "Multiple Layer Coating Method", are distinguished from coaters by extrusion or by grooves in the following manner. First, in jet coaters, the gap between the edges of the coater and the continuous coil or roll is usually greater than ten times the thickness of the fluid layer applied to the coil or continuous coil. The second difference is illustrated by comparing the matrix 60 of Figure 2 with the matrix 80 of Figure 3. Figure 3 shows how the fluid flows from the slotted die when it is not in close proximity to the continuous roll or coil. The slotted die 80 has an internal geometry and the geometry of the edge that can be used for the coating by the slot or the extrusion. It is usually positioned so that the groove 82 of the die is horizontal. Accordingly, the coating fluid 86 exiting the die groove 82 will flow vertically from the edge 84 of the die as shown if the coil or roll is moved away from the die. Sometimes, the fluid will spread down on the face 85 before it breaks freely from the body of the matrix. With a jet coater, the fluid will be dispensed as a jet from the edges of the die with a velocity large enough to form a sheet of fluid with an upper and lower free surface immediately at the outlet of the die groove. A distinctive feature of the jet coating method is that it can apply the fluid to a continuous coil or roll at some modest distance from the edges of the die relative to the thickness of the fluid jet sheet. Importantly, the flux is large enough to break freely from the edges of the matrix without the help of some other forces (such as gravity, magnetic, and electrostatic forces) and to form a free blade that moves over a measurable distance horizontally moving away from the edges. To apply ultra-thin coatings with a jet coater, a coating fluid is dosed to the die 60 and flows from the groove 70 descending onto the face 72 of the die and onto the carrier fluid 36 in the form of a jet from the groove 64. , to form a free jet 62 of composite layer. The jet forms a fluid bridge between the die and the continuous roll or coil. The angle of collision of the jet 62 with the continuous coil or roll 32, the flow velocity of the carrier fluid, and the speed of the continuous coil or roll are adjusted such that the coating fluid first contacts the coil or roll. continuous 32 and carried in the continuous coil or roll without dragging any detrimental amount of air between the coating fluid and the continuous coil or roll and without mixing the coating fluid with the carrier fluid. If an ultra-thin coating of a coating fluid that is spread or dispersed spontaneously and rapidly on the free surface of a carrier fluid is made, the apparatus shown in Figure 4 can be used. With this apparatus, a flat expense of the fluid carrier that is flowing is created by pumping the carrier fluid 36 to the die cavity 92 of a die 90, through the die slot 94, and on the face 96 of the matrix. The face 96 of the die and the flange 98 are designed because the barrier fluid 36 flows under the influence of gravity to the rim 98 of the die from which it falls as a tie curtain by means of a bridge 48 on the continuous roll or coil 32. The coating fluid 34 is deposited drop by drop or as a direct current on the surface of the carrier fluid 36 by a nozzle 100. The flow velocity of the carrier fluid and the travel time of the carrier fluid flange from which the carrier fluid is attached by means of a bridge to the surface of the coil or continuous roll in motion, should be sufficient to achieve the desired coverage. Many different devices can be used to form the composite layer. A sliding coating apparatus, a curtain coating apparatus, an extrusion coating apparatus, a slot coating apparatus, a jet coating apparatus, or a roller coating apparatus, may be used. Additionally, the composite layer can be deposited on a transfer surface, such as a band or roll, before contacting the continuous roll or coil, as shown in Figure 5. The carrier fluid 36 is removed from the roll. transfer 74 and the coating fluid is transferred to the continuous coil or roll 32 from the transfer roller. This is done by supporting the roll or continuous roll 32 on the roll 76 which forms a line of contact with the transfer roll 74. Some portion of the coating can remain on the surface of the roll 74 after transfer, to the roll or coil continuous on the contact line between the rollers 76, 74. Another variation of this coating method is shown in Figure 6. The composite layer is formed on the matrix 10 and a liquid curtain 48 is formed from the matrix to a roller 110. A precision gap 112 is maintained between the transfer roller 116 and a transport roller 114 of the continuous roll or coil, which rotates in opposite directions. The gap 112 is adjusted so that a second curtain of liquid is formed therein while allowing the entire composite layer on the transfer roller 110 to pass through the gap 112. The coil or roll continuous 32 is also carried through the gap 112 on the surface of the roller 114, and the liquid curtain makes contact therewith so that the coating fluid 34 is interposed between the surface of the continuous coil and roll and the carrier fluid 36. When the composite layer emerges from the void 112, a portion of the carrier fluid can remain on the surface of the transfer roller 110. It is removed from the transfer roller surface by a cutter 116 and drained. towards the receptacle 50. The remaining portion of the carrier fluid 36 is deposited on the surface of the wet continuous coil or roll of the coating fluid and it is removed by the action of the scraping nozzle by means of air 54 draining by gravity towards the receptacle 50. Another version of the apparatus of figure 6 is shown in figure 7. The dosed layer of the carrier fluid 36 is created in a hole of precision 120 between the edge 122 of a die 124 and the surface of a transfer roller 126. The transfer roller 126 rotates through the carrier fluid 36, contained by a tray 128, carrying an excess to the void 120. The coating fluid 34 is pumped into the cavity 12 of the die and exits the slot 42 through a hole on the surface 38 of the die. It flows down over the rim 122 and over the carrier fluid 36 when it leaves the void 120 to form a composite layer 130 which is flowing over the transfer roller 126. A precision recess 132 is maintained between the roller transfer 126 and the transport roller 134 of the coil or continuous roll, which rotate in opposite directions. The void or void 132 is adjusted so as to form a curtain of liquid therein while allowing the entire composite layer 130 on the transfer roller 126 to pass through the void or void 132. The coil or roll continuous 32 is also carried through the gap or void 132 on the surface of the transport roller 134 of the continuous roll or coil, and the liquid curtain contacts therewith so that the coating fluid 34 is interposed between the surface of the continuous coil or roll and the carrier fluid 36. When the composite layer 130 leaves the void or void 132, some of the carrier fluid may remain on the surface of the transfer roller 126 and drain back to tray 128. The fluid The remaining carrier is deposited on the surface of the coil or continuous, wet roll of the coating fluid, and is removed by the scraping nozzle by means of air 54, draining by gravity h to the receptacle 50. The coating fluid must have a combination of interfacial and viscosity properties so that it will not dehumidify from the wet surface after it is sprayed or diffused onto the surface during transport through the station. covering. Examples of the coating fluids that can be coated by this invention are monomers, oligomers, dissolved solids solutions, solid-fluid dispersions, fluid mixtures, and emulsions. Such fluids are useful for producing a wide range of functional coatings on continuous rolls or coils including release coatings, low adhesion coatings, printing layers, adhesive coatings responsive to electromagnetic radiation or to electric or magnetic fields, protective coatings, optically active coatings, and chemically active coatings. The coatings made by this invention are expected to have utility in manufacturing products such as pressure sensitive adhesive tapes, photographic films, magnetic recording tapes, gas separation membranes, signaling and sheeting. Reflectors, medical bandages, coated abrasives, printing plates, and films. This invention differs from surface expansion methods in that surface expansion techniques require an immiscible coating fluid or a fluid containing some insoluble components to spontaneously disperse or diffuse, rapidly, over a stagnant puddle of water nearby. create ultra thin films of the coating. The inventors have discovered that coating fluids, both miscible and immiscible, can flow on the surface of a moving carrier fluid as a thin or ultra-thin fluid layer. This improves the range or range of fluid coatings that can be coated. Also, in this invention, the entire composite layer forms a fluid bridge that is flowing and is transferred to the surface of the coil or continuous roll; then the carrier fluid is removed. This invention makes possible high coating speeds in excess of 500 meters per minute. Known expansion techniques are limited to less than 50 meters per minute, an order of magnitude less than this invention. With the expansion techniques, the coating fluid is deposited on the continuous coil or roll directly from the surface of a liquid tank filled with water. This water is a relatively immobile puddle or pond, with a fixed volume. Water contamination with the expansion method is always a risk. With this invention, the continuous flow of the carrier fluid helps to avoid this problem. Also with expansion techniques, a solid or solid film should be formed on the surface of the water to allow the absorption of the coating by the substrate. This invention differs from the sliding and curtain methods known as explained below. The flow of the coating fluid and the carrier fluid together form a composite layer that is flowing, stable, with an air-free fluid surface. This layer can be applied simultaneously to a moving object by forming a fluid bridge to the object composed of a plurality of different layers even when the fluids are not miscible. Graphic and photographic techniques use simultaneous multi-layer coating techniques but not carrier layers that are removed at the coating station. Additionally, the literature teaches that the fluid solvents in the formulation of these layers must be miscible. Actually, they are usually the same solvents, commonly water. The literature teaches that the interfacial tension between the fluids in the form of layers should be very low, preferably zero, and the surface tension of the adjacent layers should be slightly different. With this invention, the interfacial tension between the carrier and the coating is preferred to be as high as possible, and the surface tensions are preferred to differ widely to facilitate the removal of the carrier fluid. When the multi-layered or multi-layer curtain coating is used, the literature teaches that all layers flow in a laminar flow path manner to maintain the structure in the form of layers and to prevent mixing of the layers. With this invention, the fluids can remain unmixed even if the carrier fluid becomes turbulent. When the sliding, curtain, or slit, multi-layer coating methods are used, the literature teaches that the ratio of thickness of the adjacent fluid layers superior to the bottom is not greater than 100 to 1 and no single layer is thinner than 0.1 microns. This invention uses proportions or ratios of up to 100,000 to 1 and thicknesses of single layers as thin as 0.005 microns. Slip, curtain, and groove methods, known, can not coat a single layer or multiple layer coating, which has a total wet thickness of 5 microns or less. This invention can produce single layer coatings of 0.005 to 100 microns. When known multi-layer, multi-layer, sliding coating methods are practiced, a composite layer is created and deposited on the continuous coil or roll followed by a solidification, gelling or drying process. All the layers in the composite material remain together on the continuous roll or coil when it passes outside the coating station. Nothing is removed. In this invention, the carrier fluid of the composite material is removed by some mechanical means after the deposition of the composite material on the continuous roll or coil and before leaving the coating station. The invention is further illustrated by the following examples.

Example 1: Ultrathin Coating of an Immiscible Fluid Using the sliding curtain coating matrix shown in Figure 1, an ultrathin coating of a synthetic oil was applied to a coil or continuous roll of polyester. The coating fluid was Mobil 1® motor oil, 5W-30 manufactured by Mobil Oil Corporation of New York, New York. Its measured viscosity was 102 cp at its supply temperature of 25 ° C. The coil or continuous roll of polyester was a Scotchpar® polyester film 6 inches wide, 35.6 microns (1.4 mils), purchased from the Minnesota Mining and Manufacturing Company of St. Paul, Minnesota. The carrier fluid used was tap water from the municipal water supply without any surface tension modifying additive. The water was supplied at a temperature of 18.3 ° C to a vacuum degassing vessel, operated at a pressure of 115 mm Hg absolute. The velocity of the carrier water flow was measured both at the inlet and outlet of the degassing vessel a. empty with two identical rotometers. These were gauges from 0.2 to 2.59 gpm of model 130EJ27CJ1AA, purchased from the Brooks Instrument Corporation of Hatfield, Pennsylvania. The flow from the vessel was pumped by a continuous helical cavity type pump model 2L3SSQ-AAA, Moyno® from the Robbins & Meyers Corporation of Springfield, Ohio. To obtain a vacuum seal through this pump, it can work in reverse of its normal operation. That is, its rotor turned away from the standard direction and water was pumped from the vacuum vessel through the normal Moyno® discharge opening, through the pump and out of the feed opening. From the pump, the water flowed through a one-liter sealed compensation tank, through a fine filter, through the discharge rotometer and into the coating matrix. The flow velocity of the inlet was manually adjusted by a flow choke valve at the entry of the access rotometer. The discharge flow rate of the water from the vessel to the vacuum was controlled by the rotation speed of the Moyno® pump and verified by the discharge rotometer. During operation, the inlet flow rate was manually adjusted with the throttle valve to equal the indicated discharge speed. The filter used was a disposable filter capsule. This was purchased from the Porous Media Corporation of St. Paul, Minnesota, and identified with part number DFC1022Y050Y, calibrated for 5 microns.

The vacuum for the degassing vessel was supplied by a vacuum pump with a water ring, model MHC-25 from Nash? Ngineering Corporation of Downers Grove, Illinois. The flow rate of the carrier water was 2910 ml / minute. The coating fluid was supplied from a 60 ml syringe driven by a syringe pump at a rate of 0.2 ml / minute. The pump was a Harvard programmable syringe pump model 44, number 55-1144T which is sold by the Harvard Apparatus Corporation of South Natick, Massachusetts. During the coating, the coating matrix by a sliding curtain was placed above the roller 58 of the coating station (referring to Figure 1). More specifically, it was located so that the height of the curtain, h, was 42 rom and the curtain hit the coil or continuous roll, on the roller at an angular position of 310 ° measured in the direction of the hands of the watch from the top of the roller. The shock angle, a, was approximately 50 °. This angle was measured between the curtain and a line tangent to the surface of the continuous coil or roll at the point of contact of the curtain and the continuous coil or roll. The face 40 of the die was inclined at an angle of 85 ° from the horizontal. The width of the coating fluid groove was 18.5 cm while the width of the carrier fluid groove was 21 cm. The distribution of the holes for the slots, for the coating fluid and the carrier water were 152 and 762 microns, respectively. The diameter of the coating roller 58 was 2.5 cm. The coatings were applied to the continuous coil or roll at speeds of 45 and 73 cm / sec. The carrier fluid was simultaneously drained by gravity and blown off with a pneumatic or air knife. The hole in the nozzle of the pneumatic or air knife was 152 microns and the pressure of the nozzle was 140 Kpa. No edge guide was used, and the width of the composite curtain at the point of contact was wider than the continuous coil or roll. When the coating fluid is evenly distributed through the continuous coil or roll as in this method, the coating gauge can be calculated from the coated width, the speed of the coil or continuous roll and the fluid flow of the coating per unit width of the slot. At the indicated speeds of 45 and 73 cm / second, the coated c-fibers were calculated to be 400 and 250 Angstroms respectively. Visual inspection of the coatings indicated that the coatings were free of voids and were uniform.

Example 2: Ultrathin Coating of an Immiscible Fluid Using the sliding curtain coating matrix, and the coating fluid and the carrier fluid delivery systems described in Example 1, ultrathin coatings of a polyglycol based coating fluid were produced. The coating formulation consisted of the following percentages by weight: 90% polypropylene glycol, 9% an epoxy function silicone fluid, and 1% saturated toluene solution of a fluorescent yellow G dye. The polypropylene glycol had an average molecular weight of 4000, and is available from the Dow Chemical Company, Midland, Michigan, under the designation P4000. The silicone with epoxy function is available from the General Electric Company, Waterford, New York, under the designation GE9300. The toluene dye solution was prepared by saturating the solvent with an excess of Yellow G dye. The saturated solution was collected by decanting the liquid solution after allowing the excess dye particles to settle to the bottom of the mixing vessel. The Yellow G dye is a product of the Keystone-Ingham Corporation of Mirada, California. This coating fluid had a viscosity of 302 cp at 22 ° C. The surface tension and density were 25 dynes / cm and 0.98 g / cm3. In this example, the matrix was relocated to a position above the roller 58 where the height of the curtain was 22 mm; the angle of the face of the matrix was 75 °; and the shock angle was 45 °., The coating was first effected with a flow rate of the coating fluid of 0.1 ml / minute from a die groove 20 cm wide and at a speed of the continuous roll or coil of 100 cm / sec In case B, the flow rate of the coating fluid was 1 ml / minute and the speed of the continuous roll or coil was 15 cm / second. The flow of the water carrier fluid was 3300 ml / minute from a 26 cm wide slot. The pressure of the air nozzle, the continuous coil or roll, the width of the continuous coil or roll, and the apparatus were identical to Example 1. In case A, the coating gauge was calculated as 89 Angstroms, and in the case B the caliber was 5900 Angstroms. Case A is an ultrathin coating and case B is much thicker and is referred to as a thin coating. This example illustrates the ability of the method of this invention to coat a very wide range of thicknesses. An effort was made to quantify the uniformity of these coatings by measuring the fluorescence of the Yellow G dye in the coated samples. A photometric analyzer was used to measure fluorescent emissions at a wavelength of 500 nanometers when excited at a wavelength of 440 nanometers. The fluorescence of the 7 mm diameter points taken at random locations through and down over the continuous coil or roll were measured. The uncoated continuous coil or roll was also measured giving an average fluorescence of 2.06 relative units with a standard deviation of 0.05. In case A, the average fluorescence was 2.4 units with a standard deviation of 0.03. In case B, the average fluorescence was 24.86 units with a standard deviation of 1.41. The samples were completely coated without voids or voids present, and these fluorescence readings indicate good uniformity. The fluorescence of the dye in the coatings is proportional to the thickness of the coating. The change measured in the corrected fluorescence of the base from case A to case B is a factor of 67. This is in close agreement with the thickness change of the coating from case A to case B of 66 based on the speeds of the continuous coil or roll and the flow rates of the coating fluid.

Example 3: Coating of a miscible fluid with the Carrier Fluid Using the sliding curtain coating matrix shown in Figure 1, an ultra-thin coating of a water-soluble resin solution was applied to a coil or continuous roll of polyester. The coating fluid consisted of a solution of a Carbolpol® 940 resin dissolved in tap water. This solution was prepared by first dissolving about 1.1% by weight of the resin in water and then neutralizing the solution to a pH of 7 with a 5 weight percent sodium hydroxide solution. This created a viscous gel to which a saturated solution of Green Solvent 7 dye was added from one part of dye per 100 parts of gel. The gel is then diluted with water until a viscosity of 300 cps is obtained, when measured at 60 rpm with a. spindle LV # 4 on a Brookfield viscometer model LVTDV-II. To the diluted solution is added 0.2 grams of Silwet® 7200 surfactant per 100 g of the solution. The surface tension of the resin solution was 23.5 dynes / cm, and it was completely miscible with the tap water used as the carrier fluid during the coating. The interfacial tension between the coating fluid and the carrier fluid was zero because of the miscibility. Carbopol® is available from B.F. Goodrich Company of Cleveland, Ohio. The Solvent Green 7 dye is available from Keystone-Ingham Corporation of Mirada, California. The Brookfield viscometer is a product of Brookfield Engineering Laboratories, Inc., of Stoughton, Massachusetts. The Silwet® surfactant is manufactured by the Union Carbide Chemicals and Plastics Company, Inc. of Danbury, Connecticut. The coil or continuous roll of polyester, the carrier fluid supply apparatus, and the coating matrix were the same as those used in Example 1. The carrier fluid used was tap water from the municipal water supply without any additive modifier. the surface tension. The water was supplied at a temperature of 13 ° C to a vacuum degassing vessel operated at a pressure of 200 mm Hg absolute and then pumped into the coating matrix. The delivery rate was 3000 ml / minute. The viscosity of the carrier fluid was estimated at 1.2 cp.

During the. coating, the sliding curtain coating matrix was placed above the roller 58 of the coating station (referring to Figure 1). More specifically, it was placed so that the height of the curtain h was 3 mm and the angle of impact, a, was approximately 45 °. The face 40 of the die was inclined at an angle of 84 ° from the horizontal. The width of the coating fluid groove was 18.5 cm while the. The width of the carrier fluid slot was 21 cm. The recesses of the distributor slots for the coating fluid and the carrier water were 160 and 1100 microns, respectively. The diameter of the coating roller 58 was 2.5 cm. The carrier fluid was drained simultaneously by gravity and removed by blowing with a pneumatic or air knife. The hole in the nozzle of the pneumatic blade was 250 microns and the compressed air was supplied at a pressure of 70 Kpa. The coating fluid was supplied from a 600 ml syringe driven by a syringe pump to a delivery fluid at speeds of 11, 21.5, 50, and 100 g / min. The speed of the coil or continuous roll was kept constant at 29 cm / second. The fluorescence of the non-dried coated samples was measured at the 0.8, 1.4, 2.4, and 5.0 relative fluorescence units for the four pumping rates of the coating fluid respectively. Coating weights as indicated by fluorescence varied linearly with the pumping rate of the coating fluid. This example again illustrates that the weight of the coating responds directly to the pumping rate of the coating fluid. The example also demonstrates that combinations of miscible carrier and coating fluids can be used successfully.

Example 4: Coating of the Immiscible Fluid with a Jet Coating Apparatus Using the jet coating matrix in FIG. 2, a thin coating of a UV curing solution was applied to a coil or continuous roll of polyester. A syrup was prepared by mixing 90 parts of isooctyl acrylate with 10 parts of acrylic acid and 0.04 parts of benzyl dimethyl ketal (Irgacure® 651 from Ciba Geigy). The mixture was diffused or dispersed with nitrogen, and partially polymerized to a syrup having a viscosity of about 3000 centipoise by exposure to ultraviolet light fluorescent lamps. An additional 0.15 parts of benzyl dimethyl ketal was added to the syrup. The UV curing solution was prepared by mixing 66.9 grams of the resulting syrup with 220 grams of the isooctyl acrylate. To this was added one part by weight of the Yellow G dye solution described in Example 2 for every 20 parts of the solution. Silwet® 7200 surfactant was also added in proportions of one part per 2000 parts of the solution by weight. A viscosity of 700 cp was obtained when measured at 60 rpm with a spindle of number 4 on a Brookfield viscometer model LVTDV-II for this formulation. The continuous polyester coil or roll, the coating fluid supply apparatus, and the carrier fluid delivery apparatus were the same as those used in Example 1. The carrier fluid used was tap water from the municipal water supply without some additive modifier of surface tension. The water was supplied at a temperature of 12 ° C to a vacuum degassing vessel operated at a pressure of 200 mm Hg absolute and then pumped into the coating matrix. The delivery rate was 4100 ml / minute. The viscosity of the carrier fluid was estimated at 1.2 cp. During the coating, the jet coating matrix was placed above the roller 56 of the coating station as illustrated in Figure 2, with the groove 64 of the carrier fluid oriented horizontally. The coil or continuous roll was moved vertically downwards until the matrix was passed at a horizontal spacing of 3.7 cm. The jet composed of the carrier fluid and the coating fluid was bent downwards by gravity and collided on the continuous roll or coil at an acute angle. No edge guide was used and the composite jet contracted to a width of 10 cm at the point of contact with the continuous roll or coil. The width of the coating fluid groove was 18.5 cm while the width of the carrier fluid groove was 21 cm. The gaps in the distribution slot for the coating fluid and the carrier water were 150 and 280 microns, respectively. The carrier fluid was drained simultaneously by gravity and removed by blowing with a pneumatic or air knife. The hole of the nozzle of the pneumatic blade was 250 microns and the compressed air was supplied thereto at a pressure of 210 Kpa. The coating fluid was supplied at speeds of 2, 4, and 8 ml / minute. The speed of the coil or continuous roll was kept constant at 29 cm / second. The solution of the polymer and the monomers was polymerized by the application of UV light to form a gel. The fluorescence of the coated, gelled samples was measured at 0.8, 1.4, 2.4, and 5.0 relative fluorescence units for the four pumping speeds of the fluid respectively. Coating weights as indicated by fluorescence varied linearly with the pumping rate of the coating fluid. The calculated coating sizes were 10000, 21000, and 43000 Angstroms. This example illustrates again that the weight of the coating corresponds directly to the pumping rate of the coating fluid. The example also demonstrates that the combinations of the immiscible coating fluid and the carrier fluid can be successfully used with the coating method to achieve tensile calibres of tens of thousands of Angstroms.

Example 5: Release Coating Prepared from a Fluoropolymer Using the sliding curtain coating matrix shown in Figure 1, an ultra-thin coating of a UV polymerizable fluid of the fluoropolymer was applied to the coil or continuous roll of polyester. The coating fluid consisted of an acrylic functional perfluoropolyether as described in U.S. Pat. No. 4,472,480 (Compound II). The coil or continuous roll of polyester, the carrier fluid supply apparatus, the coating supply apparatus, and the coating matrix were the same as those used in Example 1. The carrier fluid used was tap water from the supply of municipal water without some additive modifier of the superficial tension. The water was supplied at a temperature of 7 ° C to a vacuum degassing vessel operated at a pressure of 200 mm Hg absolute and then pumped into the coating matrix. The viscosity of the carrier fluid was estimated at 1.4 cp. The viscosity of the coating fluid was 40 cp. The surface tension of the coating fluid was 19 dynes / cm, and the density was 1. 7 g / cm3. All these properties were measured at 23 ° C. In this example, the matrix was relocated to a position above the roller 58 where the height of the curtain ranged from 68 to 84 mm; the angle of the face of the matrix was 75 °; and the shock angle was 35 ° to 45 °. The width of the groove of the matrix of the carrier fluid was 25 cm and the gap or vacuum was 0.76 mm. The width of the groove of the matrix of the coating fluid was 25 cm and the gap was 0.165 mm.

The velocity of the pneumatic or air nozzle and the apparatus were identical to Example 1. Table 1 gives the flow rates of the carrier and coating fluid, the speeds of the coil or continuous roll, and the UV curing dosages used. in the preparation of the samples. The caliper of the calculated coating and the resulting, measured release values are also given. Operation of the release of the coated samples was measured against a commercially available silicone pressure sensitive adhesive (DC 355, available from the Dow Corning Corporation of Midland, Michigan). The adhesive was coated directly onto the ultra-thin fluorochemical layer at a coating thickness of the 200 micron continuous coil or roll, and the solvent was allowed to dry overnight at room temperature. A 50 micron sheet of the polyester film was laminated to the dry adhesive layer, and this polyester sheet, in the adhesive company, was aged 72 hours at room temperature, then it was detached from the fluorochemical coating at a peel angle. 180 ° and at a speed of 3.8 cm / second.

Table 1 : Flow Flow Rate Dosifi- Fluid Value of Fluid coil or _ _. Libera¬ ration Rarta- RecuCali- SAMPLE "UV" roll, continuous flow rate (millijoules / n (ml / min) (ml / min) (cm / sec) (A) crr (g 2.5cm) • 36 2400 0.200 102 216 50 76? 44 2400 0.300 106 310 4g It can be seen that functional release coatings are obtained, when compared to the uncoated continuous coil or roll, where the release value exceeds 1500 g / 2.5 cm.

Example 6: Releasable Coating Prepared from a Thermally Cured Silicone Using the sliding curtain coating matrix shown in Figure 1, an ultra-thin coating of a thermally polymerizable silicone fluid was applied to the continuous coil of paper and polyester. The coating fluid consisted of a solvent-free, thermally cured silicone, as described in U.S. Pat. No. 4,504,645 (Example 1, Sample 1). The continuous paper roll or coil was a super calendered, natural 27.24 kg (60 lb.) kraft paper, supplied by Nicollet Paper Company, Depere, Wisconsin. The carrier fluid supply apparatus, the polyester, the coating fluid supply apparatus and the coating matrix were the same as those used in Example 1. The carrier fluid used was tap water from the municipal water supply without any additive modifier of surface tension. The water was supplied at a temperature of 8 ° C to a vacuum degassing vessel operated at a pressure of 200 mm Hg absolute and then pumped into the coating matrix. The viscosity of the carrier fluid was estimated at 1.3 cp. The viscosity of the coating fluid was 257 cp. The density was 0.97 g / cm3, and the surface tension was 20.7 dynes / cm. All these properties were measured at 23 ° C. In this example, the matrix was relocated to a position above the roller 58; the angle of the face of the matrix was 75 °; and the shock angle was 45 °. The pressure of the pneumatic or air nozzle was 140 Kpa and the gap of the nozzle groove was 0.25 mm. The width of the coating fluid groove was 23 cm while the width of the carrier fluid groove was 25 cm. The gaps in the distribution slot for the coating fluid and the carrier water were 150 and 760 microns, respectively. Table 2 gives the flow rates of the coating fluid, the caliper of the calculated coating, and the measured release values of the samples prepared. In all cases, the height of the curtain was 34 mm; the speed of the continuous roll or coil was 25 cm / second; the flow rate of the carrier fluid was 3000 ml / minute. The coated samples were cured in an oven at 150 ° C for two minutes. The release values were measured by laminating a 2.54 cm wide strip of Scotch® 610 adhesive tape to the silicone coating using a 2 kg roller. After 24 hours, the tape was detached from the silicone coating at an angle of 180 ° and at a speed of 3.8 cm / second.

Table 2: Caliber FLOW BOBINE 0 Fecubri- of Release Release SAMPLE FOLLÓ aCNTINUO BrIMLento n U (l min) (A) (g / 2.5 cm) bl polyester 0.38 997 295 b2 polyester 0.3 B 997 103 b3 polyester 1.75 4600 26 b4 polyester 1.75 4600 27 bS paper 1.75 4600 27 b6 paper 1.75 4600 34 Example 7: Release Coating Prepared from a UV Cured Silicone Using the sliding curtain coating matrix shown in Figure 1, the ultrathin coatings of a UV polymerizable epoxysilicone fluid, as described in Example 3 of U.S. Pat. No., 5,332,797, were applied to a coil or continuous roll of polyester. The coating fluid was a mixture of 95 parts of epoxysilicone with an epoxy equivalent weight of 538.2 parts of bis (dodecylphenyl) iodo hexafluoroantimonate, 3 parts of Alfol® 1012 HA (a mixture of alkyl alcohols), and 0.2 parts of 2-isopropylthioxanthone. The carrier fluid supply apparatus, the polyester continuous coil or roll, the coating supply apparatus, and the coating matrix were the same as those used in Example 1. The carrier fluid used was tap water from the supply of municipal water without some additive modifier of surface tension. The water was supplied at a temperature of 16 ° C to a vacuum degassing vessel operated at a pressure of 200 mm Hg absolute and then pumped into the coating matrix. The viscosity of the carrier fluid was estimated at 1.1 cp. The viscosity of the coating fluid was 276 cp. The surface tension of the coating fluid was 23 dynes / cm, and the density was 1. 01 g / cm3. All these properties were measured at 23 ° C. All coatings were prepared at a line speed of 25 cm / sec and then passed at the same speed under a single medium pressure mercury lamp at 60 watts per cm to give a tack-free release coating Cured Several coating weights were applied by changing the pumping speed of the coating fluid, and the results are given in Table 3. The release values of the coatings were by the coating of an acrylic pressure sensitive adhesive, i.e. isooctyl acrylate copolymer: acrylic acid 95.5: 4.5 as described in US Pat. No. RE 24,906, directly on the release coating using heptane as the solvent. After coating, the adhesive was dried in an oven at 70 ° C for 5 minutes, and a 50 micron thick polyester film was laminated to the adhesive layer. This laminate was heated in an oven at 70 ° C for 72 hours. The aged laminate was cut into strips of 2.5 x 25 cm and fixed, the substrate is turned down, to a glass plate using a double adhesive tape. The release value is the force, in grams, required to pull the polyester film with the pressure-sensitive adhesive adhered to it, pulling it from the substrate coated releasably at an angle of 180 ° and at a pulling speed of 230 cm /minute.

Table 3: Release Liberation Readhesion (28 q / 2.54 cm) Caliber Starts L Aged (A) (g /2.54 c) (g 2.54 cm) Initial E vejecicb 250 61 294 63 57 500 89 73 59 60 1000 86 63 62 63 1500 86 58 62 64 2000 80 52 65 63 2500 77 59 66 66 3000 73 64 67 69 7000 »64 50 66 62 * n-estra coated with 5 roller. s for reference "Initial" Values at 3 days / room temperature with the expansion of the adhesive on the "Ehvejecido" coater Values at 3 days / 70 ° C expansion or swelling of the adhesive on the coater Example 8: Coating of Cured Epoxy with UV Using the sliding curtain coating matrix shown in Figure 1, a thin coating of a UV polymerizable epoxy resin fluid was applied to a continuous coil or roll of polyester. The coating fluid was a solvent-free resin blend of 50% ERL 4221 and 50% UVR6379 to which was added an additional 1% by weight of Silwet® 7500 surfactant and 3% by weight of UVI photoinitiator 6971 all supplied by the Union Carbide Corporation, New York, New York. The coil or continuous roll of polyester, the coating fluid supply apparatus, and the carrier fluid supply apparatus were the same as those used in Example 1. The carrier fluid used was tap water from the municipal water supply without some additive modifier of surface tension. The water was supplied at a temperature of 8 ° C to a vacuum degassing vessel operated at a pressure of 200 mm d Hg absolute and then pumped into the coating matrix. The viscosity of the carrier fluid was estimated at 1.3 cp. The viscosity of the coating fluid was 352 cp. The surface tension of the coating fluid was 27 dynes / cm, and the density was 1.11 g / cm3. All these properties were measured at 23 ° C. When coating this material a great tendency was observed to trap the air between the coating fluid and the surface of the continuous coil or roll. This could be eliminated by applying a high voltage potential to the coating roll.

In this example, the matrix was relocated to a position above the roller 58 where the height of the curtain was 5 mm; the angle of the face of the matrix was 75 °; and the shock angle was 45 °. The pressure of the nozzle for the air was 140 Kpa and the gap of the slot of the nozzle was 0.25 mm. The width of the groove for the coating fluid was 23 cm while the width of the groove for the carrier fluid was 25 cm. The gaps in the distribution slot for the coating fluid and the carrier water were 150 and 760 microns, respectively. Table 4 gives the flow rates of the coating fluid, the electrostatic potential, and the speeds of the coil or continuous roll used in the preparation of the samples. The caliper of the calculated coating is also given. The coatings were cured by passing them under a single, medium pressure mercury lamp, mounted in line with the coating apparatus. The coating appeared completely cured, uniform, and free from defects during a visual inspection.

Table 4: Velocidac Poten¬ MUESIRA Flow Flow Coil or Dosage Cali Fluid Fluid Rollo bre Roller UV Carrier Continuous Recruitment of "e-cu (milijoules / u d.) (ml / min) (ml min) (cm sec) (A) cm cm (volt) brce cl 2080 2.0 7.62 17500 700 400 c2 2080 6.0 6.60 60000 800 462 Example 9: Release Coating Prepared from a Miscible Silicone Latex Release Agent Using a sliding curtain coating matrix shown in Figure 1, a thin coating of a water miscible silicone latex release agent was applied to a coil or continuous roll of polyester. The coating fluid was a water-based latex heat-curing resin blend of GE Silicones from Waterford, New York consisting of 10 parts of the latex SM2145 and 1 part of the latex SM2146c. For samples a and b, the undiluted mixture was coated at a viscosity of 284 cp as measured by a Brookfield viscometer at 60 rpm with an LV # 2 spindle. For samples c and d, the mixture was diluted with water to the proportion of 10 parts of water with respect to 1 part of the latex mixture, then the thickening agent Natrosol 250HR is added to give a viscosity of 2300 cp by the Brookfield apparatus. at 60 rpm with the spindle LV # 3. The thickening agent is manufactured by Hercules, Inc. of Wilmington, Delaware. The surface tension and the density of the mixed latex before dilution were 27 dynes / cm and 0.98 g / cm3. The surface tension between the latex mixture and the carrier water was zero; the latex was miscible with the carrier water. The carrier fluid supply apparatus, the continuous polyester coil or roll, the coating supply apparatus and the coating matrix were the same as those used in Example 1. The carrier fluid used was tap water from the water supply municipal without some additive modifier of the surface tension. The water was supplied at a temperature of 9 ° C to a vacuum degassing vessel, operated at a pressure of 200 mm Hg absolute and then pumped to the coating matrix. The viscosity of the carrier fluid was estimated at 1.3 cp. The carrier water supply apparatus was as described in Example 1. In this example, the matrix was located above the roller 58 where the height of the curtain was 10 mm; the angle of the face of the matrix was 75 °; and the shock angle was approximately 45 °. The gap of the slot of the air nozzle was 0.25 mm. Table 5 gives the caliper of the calculated silicone, the speeds of the roll or continuous roll, and the pressures of the air nozzle used in the preparation of the samples in the company of the results of the release. The coated samples were dried and cured in a batch oven for 10 minutes at 120 ° C. The coating seemed uniform, totally cured and free of defects during a visual inspection. The release of these coatings was evaluated using ana Scotch® 810 Tape. A strip of 2.54 cm wide tape was laminated to the cured coatings and rolled down with a 2 kg cylinder or roller. The release was measured by detaching the backside of the tape from the substrate coated with silicone at an angle of 180 ° at a speed of 228.6 cm / minute. The force required to detach the tape was averaged over a 5-second detachment and is reported in grams per 2.54 cm (1 inch) in width. A control of the base polyester produces a release of 661 g / 2.54 cm.

Table 5: Speed Pressure "VUESTRA Coil or Caliber of the roll nozzle Continuous release of air U (cm / jec) (A) (pi) (g / 2.54 cm) 8 14 24000 70 5 b 54 4300 140 6 c 65 930 70 102 d 74 400 70 261 Example 10: Coating of a Miscible Latex Adhesive In this example, the apparatus of Example 1 was used with the exceptions that first a larger syringe pump was used and secondly that the carrier fluid was recirculated continuously from a 60 liter tank. The vacuum degassing tank 36 in Figure 1 was replaced by this containment tank which was physically located so that the fluid from the receptacle 50 could be drained by gravity towards it, thereby allowing recirculation of the carrier fluid.

The thin coatings of a water-miscible, 45% solids latex adhesive was applied to the coil or continuous roll of polyester. The latex was a Sequabond DW-1 purchased from Sequa Chemicals, Inc., of Chester, South Carolina. Its viscosity was measured as 28,600 cp on a Brookfield viscometer with a # LV2 spindle at 0.3 rpm at 21.7 ° C. The surface tension of the coating fluid was 39.4 dynes / cm, and the density was 1.0 g / cm3. All these proportions were measured at 21 ° C. The carrier fluid used was tap water from the municipal water supply without any additive modifying the surface tension. The water was supplied to tank 36 and allowed to warm to 21 ° C before use. During the coating, the polyethylene film strips were placed on top of the continuous roll or coil at each edge of the continuous roll or coil. These extended from 2.2 cm from the edge of the continuous coil or roll to the outside, to the edge of the coating matrix. They were to prevent the adhesive from wetting the roller 58 of the coating station, while leaving an uncoated margin at each edge of the continuous roll or coil. The fluids both carrier and coating from the two edge regions were directed towards it. receptacle 50. There they were intermixed with the carrier fluid blown away from the continuous coil by the gas jet 52. One result of this was that the carrier fluid became contaminated with the latex coating fluid. The carrier fluid velocity was 1000 ml / minute, and the viscosity was measured as 1.06 to 1.40 cp. The pressure of the air nozzle was 20 Kpa. The slots for the carrier and coating fluids were 25.8 and 25.2 cm wide and had gaps of 0.49 and 0.25 mm respectively. Table 6 gives the flow velocity of the latex mass and the coating gauges obtained at the speed of the coil or continuous roll of 27 cm / sec, a fraction of solids of the latex of 0.45, and a hollow nozzle for the air with respect to the continuous coil or roll in the range of 1 to 2 ml. The coating appeared uniform, functional and free from defects during a visual inspection.

Table 6: Flow Caliber Caliber of Recubridel Recubride latex dry drying wet (g / cm-iec :) (A) (A) 0.0786 160000 350000 0.0302 62000 138000 0.0496 46000 102000 0.0151 38000 84000 0.0060 15000 33000 0.0030 8000 17000 0. 24 470000 1040000 Example 11: Release Coating Prepared from a Solvent Solution Using the sliding curtain coating matrix shown in Figure 1, an ultrathin coating of a urethane release coating was applied to the side treated with a coil of a continuous coil or biaxially oriented polyethylene roll of 25 microns in size. The coating fluid was a 1.1% urethane polymer solution in a solvent consisting of 1 part toluene, 1 part tetradecane, and 2 parts xylene. The urethane release polymer labeled with a fluorescent agent was prepared as in U.S. Pat. No. 4, 978,731 (Example 2) with the exception that the solvent mixture described above was used. The viscosity of the coating fluid was estimated as 0.7 cp. The surface tension of the coating fluid was 25 dynes / cm, and the density was 0.9 g / cm3. All these properties were measured at 24 ° C. Various coating weights were applied by changing the speed of the continuous roll or coil while maintaining the pump speed of the syringe pump of Example 1 by distributing the coating fluid at 5 ml / minute from a 14 cm wide slot . The flow rate of the carrier water was 2800 ml / minute, and the heights of the curtain varied from 3 to 16 mm. The carrier fluid was tap water from the municipal water supply without any additive that modifies the surface tension. The water was supplied at a temperature of 27 ° C to a vacuum degassing vessel operated at a pressure of 200 mm Hg absolute and then pumped into the coating matrix. The viscosity of the carrier fluid was estimated at 1 cp. The carrier water delivery apparatus was as described in Example 1. The fluorescence measurements indicated the dry cover and full coverage weights that were proportional to the speed of the continuous coil or roll. The release values are given in Table 7. The operation of the release was evaluated by laminating a 2.54 cm wide strip of the Scotch® 810 Magic Tape, purchased from Minnesota Mining and Manufacturing Company, St. Paul, Minnesota, at Dry coatings using a 2 kg roller. The tape strips were then peeled off, from the ultra-thin coatings at a 180 ° angle and at a peel rate of 3.8 cm / second.

Table 7 Release C = ú bre (g / 2.54 cm) (A) 64 320 128 210 257 310 758 190 non-coated film 495 Example 12: Coating with a High Viscosity Carrier Fluid, not Aqueous Using the sliding curtain coating matrix shown in Figure 1, an ultrathin coating of an epoxy silicone resin solution was applied to a coil or continuous roll of polyester. The coating fluid consisted of a 35% solution of epoxysilicone fluid described in Example 7 dissolved in the nonane solvent. Its viscosity was 9 cp, and the surface tension of the resin solution was 24 dynes / cm. The density of the coating was 1.0 g / cm3. The carrier fluid was Dowtherm® SR-1 ethylene glycol heat transfer fluid from the Dow Chemical Company of Midland, Michigan. Its viscosity was 18 cp., And the surface tension was 34 dynes / cm. The density of the carrier fluid was 1.14 g / cm3. The carrier fluid was supplied from a tank at a temperature of 22 ° C and pumped to the coating matrix using a gear pump. The delivery rate was 2700 ml / minute. The coil or continuous roll of polyester was the same as that used in Example 1. The coil or continuous roll of polyester, the coating fluid supply apparatus and the coating matrix were the same as those used in Example 1. During the coating, the sliding curtain coating matrix was placed above the roller 57 of the coating station as in example 3, with a curtain height of 7 mm. The impact angle was approximately 45 °. The width of the coating fluid groove was 24 cm while the width of the carrier fluid groove was 25 cm. The gaps in the distribution slots for the coating fluid and the carrier fluid were 160 and 800 microns, respectively. The carrier fluid was drained simultaneously by gravity and was removed by blowing with a pneumatic blade. The hole in the nozzle of the pneumatic blade was 250 microns and the compressed air was supplied to it at a pressure of 200 Kpa. The residual droplets of the glycol were washed from the surface of the samples obtained with the water. The coating fluid was supplied from a 60 ml syringe driven by a syringe pump to deliver the fluid at a rate of 0.5 g / minute. The speed of the coil or continuous roll was kept constant at 19 cm / second. The continuous coatings were observed in the samples. The wet gauge calculated for these conditions was approximately 1700 Angstroms. This example demonstrates that the combinations of the immiscible carrier fluid and the coating fluid can be used where the carrier is not water. It demonstrates the use of a higher viscosity carrier than the coating fluid. Many variations of the described systems can be used. For example, the layer that is flowing from the carrier fluid need not be formed by flowing from a slot in a matrix. It can be formed from the flow on a landfill or an open trough. Also, the composite layer does not need to be formed on the matrix. The coating fluid can be deposited on the carrier fluid after it leaves the edge of the matrix. Also, a multilayer carrier fluid and a multilayer coating fluid can be used. A multilayer carrier fluid could have a pure top layer and a recycled bottom layer.

It is noted that in relation to this date the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following

Claims

1. A method for coating a substrate 32 with a layer, characterized in that it comprises the steps of: moving the substrate 32 along a path through a coating station; forming a composite layer 48 comprising at least one coating fluid 34 and at least one carrier fluid 36 having a formulation different from that of each coating fluid; flowing the composite layer 48 at a rate that is sufficient to form a fluid bridge continuously flowing from the composite layer to the substrate 32 for the coating of the width, wherein the portion of the composite layer of the carrier fluid 34 is continuous; contacting the substrate 32 with the composite layer 48 that is flowing, to interpose the coating layer 34 between the substrate 32 and the carrier fluid 36; and removing the carrier fluid 36 while leaving the coating fluid 34 deposited on the substrate as a coating layer.

2. The method according to claim 1, characterized in that the step of providing the fluidity comprises flowing the composite layer 48 at a speed that is sufficient to form a fluid bridge that flows continuously to the substrate 32 for the coating of the width, without it being high enough to form a fluid bridge that flows continuously, only from the coating fluid.

3. The method according to claim 1, characterized in that the step of removing the carrier fluid 36 comprises at least one of the steps of mechanical scraping, drainage by gravity, centrifugal removal, blowing, and suction, solidification of the carrier followed by scraping, magnetic attraction, absorption by contacting it with a solid absorbent material, gelation of the carrier then scraping, gelation of the coating then scraping, solidification of the coating then scraping, adsorption of the carrier fluid, and chemical bonding of the coating followed by mechanical removal of the carrier.

4. The method according to claim 1, characterized in that the thickness of the coating deposited on the substrate is less than 50 microns.

5. The method according to claim 1, characterized in that the movement step comprises moving the substrate 32 through the coating station at speeds of up to 2000 m / minute.

6. The method according to claim 1, characterized in that it further comprises the step of selecting a carrier fluid 36 which is not miscible with the coating fluid 34, which has a viscosity lower than that of the coating fluid, and which has a surface tension greater than the coating fluid.

7. The method according to claim 1, characterized in that the substrate 32 is a transfer surface 110.

8. The method according to claim 1, characterized in that the step of forming a composite layer 48 comprises using the carrier fluid 36 which is immiscible with the coating fluid 34 with which it forms an interface and wherein the carrier fluid has properties humectants that cause it to not remain as a continuous film covering the surface of the first and second substrates coated with a coating fluid.

9. The method according to claim 8, characterized in that it further comprises the step of depositing on the substrate 32 the coating fluid 34 to the wet calibers of between 25 and 10000 angstroms.

10. The method according to claim 1, characterized in that the step of forming a composite layer 48 comprises using the carrier fluid 36 which is immiscible with the coating fluid 34 with which it forms an interface and wherein the carrier fluid it has wetting properties which cause it to remain as a continuous film covering the surface of the first and second substrates coated with the coating fluid.

11. The method according to claim 1, characterized in that the step of forming a composite layer 48 comprises using the carrier fluid 36 that is miscible with the coating fluid 34, with which it forms an interface.

12. The method according to any of claims 10 and 11, characterized in that it further comprises the step of depositing on the substrate the coating fluid at wet calibers greater than 10000 angstroms.

13. The method according to claim 12, characterized in that the step of forming a composite layer 48 comprises preventing the carrier fluid 36 from remaining as a continuous film covering the surface of the substrate coated with the coating fluid after the deposition step. and after the scraping step while the substrate is in the coating station.

14. The method according to claim 1, characterized in that the step of removing the carrier fluid 36 comprises removing at least ten percent of the carrier fluid without drying the carrier fluid while leaving the layer of the coating fluid 34 deposited on the carrier fluid. substrate

15. The method according to claim 14, characterized in that the step of removing the carrier fluid 36 comprises removing the carrier fluid without removing it by blowing with a pneumatic or air knife.

16. The method according to claim 1, characterized in that the step of removing the carrier fluid 36 comprises removing the carrier fluid after the solidification or gelling of the carrier fluid and after gelation, solidification or chemical reaction of the coating fluid.

17. An apparatus for coating a substrate with an ultrathin layer, characterized in that it comprises: a matrix 10, 60, 80, 90 for expelling a carrier fluid 36; means for depositing at least one coating fluid 34 on the carrier fluid 36, wherein the carrier fluid has a formulation different from that of each coating fluid, to create a plurality of fluid layers that are flowing in face-to-face contact each other to form a composite layer 48; means for moving the substrate at a distance spaced from the die to allow the composite layer to form a fluid bridge continuously flowing to the surface of the substrate to coat the width and to deposit the coating layer on the substrate; and means for removing the carrier fluid while leaving the coating fluid deposited on the substrate as a coating layer.

18. The apparatus according to claim 17, characterized in that the matrix 10, 60, 80, 90 has a face 40, a groove 44 communicating with the face, and an edge 46, wherein the carrier fluid 36 comes out from the groove on the face and flows along the face to the flange, wherein the deposition means deposits the coating fluid 34 on the carrier fluid while the carrier fluid flows along the face, and wherein the composite layer is transported along the face of the matrix to the rim of the matrix.