Apparatus for applying a liquid coating, method for coating the surface of a substrate, and method for manufacturing a sandwich panel.
Patent Information
- Application Number
- JP2026505999
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-07-31
- Filing Date
- 2024-07-30
- Publication Date
- 2026-09-03
Smart Images
Figure 2026529904000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for producing a sandwich panel comprising a first sheet, a second sheet, and a foam layer applied between the first sheet and the second sheet, the method comprising: applying a primer to an inner surface of the first sheet; applying a reaction mixture containing a reactant for producing a polymer and a blowing agent to the primer on the inner surface of the first sheet, wherein after application, the reaction mixture starts to react and expand, thereby forming the foam layer; applying a primer to an inner surface of the second sheet; and feeding the second sheet such that the primer on the inner surface of the second sheet is arranged against the foam layer, thereby forming the sandwich panel.
[0002] Sandwich panels produced by this method are used, for example, as facade members in buildings, particularly in the commercial field such as warehouses and industrial buildings, for example, workshops, sports halls, department stores or assembly shops. In addition to use as facade members, sandwich panels can also be used as insulating panels in cold storage warehouses, climate chambers, or truck bodies. In many cases, sandwich panels are also referred to as composite members or sandwich members.
[0003] Sandwich panels are typically produced by a continuous process in which first and second sheets are fed to an application apparatus, where a primer is applied to the inner surface of the first sheet for better adhesion of the foam layer to the inner surface of the first sheet. Methods for applying a primer to a first sheet are described, for example, in WO 2006 / 120234, EP-A 2412526, WO 2010 / 060864, or EP-A 1593438. In these methods, the primer is applied only to the sheet that forms the exterior of the building. Typically, the sheet forming the exterior of the building is exposed to greater stress due to heating and thermal expansion from wind loads or solar radiation compared to the sheet forming the interior of the building.
[0004] However, the main reason for applying the primer only to the first sheet is the difficulty of uniformly applying the primer to the inner surface of the second sheet, because during the manufacturing process, the inner surface faces downwards.
[0005] In International Publication No. 2015 / 155138, a rotary roller or rotary brush is used to apply a primer to the inner surface of the second layer, which is positioned opposite the inner surface of the first layer. The rotary roller or rotary brush transfers the primer from the inner surface of the first layer to the inner surface of the second layer. After applying the primer to the inner surfaces of the first and second sheets, the reaction mixture is applied, and the composite, including the first and second sheets coated with primer on their inner surfaces and the reaction mixture applied on top, is fed into a double belt, where the reaction mixture is reacted and expanded to form a foam layer.
[0006] In addition to using a rotary roller or rotary brush to apply the primer to the second sheet, a method of applying the primer using a tube with an opening to which a small hose is connected is also known. In this method, the primer is applied to the inner surface of the second sheet via a hose that is in contact with the inner surface of the second sheet.
[0007] However, a drawback of all methods for applying primer to the second sheet is that, because the inner surface of the second sheet is facing downwards, the primer may be applied unevenly or drip, resulting in contamination of the inner surface of the first sheet. In addition, a uniform layer of primer cannot be applied, especially when applied using a tube connected to a hose.
[0008] Therefore, the object of the present invention is to provide an apparatus for coating the surface of a substrate, which can coat the surface with a uniform coating even if the surface does not extend horizontally or is the underside of the substrate; a method for coating a surface, which involves applying a primer to the inner surface of a second sheet to form a uniform coating without dripping; and a method for continuously manufacturing sandwich panels.
[0009] This objective is achieved by an apparatus for applying a liquid coating to the surface of a substrate, comprising a tube for supplying the liquid coating and a pad made of a porous material, wherein the tube has at least one opening extending parallel to the main axis of the tube, and / or the tube has a plurality of openings arranged in a row parallel to the main axis of the tube, through which the liquid coating can be supplied to the pad, the apparatus having a metering device for supplying the liquid coating to the tube at a predetermined pressure, the pad being placed in a trough, the tube being placed below the trough, and at least one or more openings of the tube being in fluid contact with openings on the underside of the trough so that the liquid coating can flow from the tube into the trough and uniformly permeate the pad.
[0010] A further objective is a method for coating the underside of a substrate by such an apparatus for applying a liquid coating to the rectangular surface of the substrate, (i) In order to impregnate the pad with the liquid coating, supply the liquid coating from the tube to the trough through at least one opening, and (ii) This is achieved by a method that includes passing the surface of the substrate along the surface of the pad under a predetermined pressure so that the liquid coating is applied to the surface of the substrate.
[0011] A device for applying liquid coatings can be used to apply a uniform coating to the entire surface of a substrate. The liquid coating is applied to the substrate surface as long as pressure is applied to the surface of the pad in contact with the substrate surface. As soon as the pressure on the pad is released, the supply of the liquid coating stops.
[0012] Placing the pad within the trough has the added advantage of preventing dripping through the pad portion and thus preventing contamination of the coating device or the inner surface of the first sheet.
[0013] To ensure uniform immersion of the pad with the liquid coating, it is preferable that at least one opening be positioned so that the liquid coating can flow into the pad along its entire length. For this purpose, the at least one opening may be in the shape of a slot extending along the main axis of the tube. Alternatively, multiple openings may be provided. In this case, the multiple openings are arranged in a row parallel to the main axis of the tube. Furthermore, it is preferable that the distance between the openings be constant. When multiple openings are provided in a row, the openings can have any cross-sectional shape, such as circular, elliptical, rectangular, square, or polygonal with any number of vertices. However, in this case, for manufacturing reasons, it is particularly preferable that the openings be circular or slots.
[0014] By using a pad made of a porous material, it is possible to meter and supply the liquid coating so that it seeps out of the porous material only insofar as the surface of the substrate is in contact with the pad. The seeping of the liquid coating ends as soon as contact between the surface of the substrate and the porous material of the pad is lost. This can be achieved, for example, by using a compressible porous material that is compressible under pressure and returns to its initial shape as soon as the pressure acting on the porous material is removed. In this case, the porous material for immersing the surface of the substrate is pressed against the porous material. To achieve this, the compressible porous material is embedded in a trough that holds the liquid and prevents dripping. In order to press the surface of the substrate against the compressible porous material, the side walls of the trough need to be lower than the height of the compressible porous material when it is not compressed. The liquid coating to be coated on the surface of the substrate is released by compressing the porous material. For the liquid coating to be able to flow out of the porous material, it is preferable that the porous material is saturated with the liquid coating, at least in the area where the surface of the substrate is pressed. The volume decreases due to the compression caused by the pressing of the substrate surface against the porous material, and the liquid coating flows uniformly out of the porous material and is applied to the substrate surface, forming a uniform coating. As soon as no further pressure is applied to the porous material, it returns to its original shape, and the liquid coating is retained within the trough and does not flow out further.
[0015] Alternatively, the liquid coating may be replenished by capillary action transferring the liquid coating from the porous material to the surface of the substrate being coated, and by capillary action within the porous material causing the liquid coating to seep out. In this case as well, the liquid coating seeps out of the porous material only if the porous material is in contact with the surface of the substrate being coated.
[0016] To enable the movement of the liquid coating to the surface of the pad in contact with the surface of the substrate to be coated, it is preferable that the porous material allows the liquid to move along its length by capillary force. In this case, the cross-sectional shape of the porous material perpendicular to the supply direction of the substrate may be any arbitrary shape. The cross-sectional area of the pad perpendicular to the supply direction of the second sheet may be circular, rectangular, or square.
[0017] When a liquid coating is applied to the surface of a substrate by pressing the substrate surface against a porous material, it is necessary to provide a device for pressing the substrate surface against the porous material. Such a device may be, for example, a roller that acts on the substrate, thereby pressing the surface of the substrate to be coated against the porous material.
[0018] The porous material may be any type that can transfer the liquid coating to the surface of the substrate, and may be, for example, felt, woven fabric, nonwoven fabric, perforated elastic material, or open-cell foam. Particularly preferred is the porous material to be an open-cell foam having a cell size having an average diameter in the range of 70 to 1500 μm, more preferably in the range of 70 to 800 μm, more preferably in the range of 70 to 500 μm, and especially in the range of 70 to 250 μm. Particularly preferred is the porous material to be a foam composed substantially of only cell webs. In the context of the present invention, "substantially composed of only cell webs" means that more than 90% of the foam, preferably more than 95% of the foam, and especially more than 98% of the foam, has only cell webs and no cell walls.
[0019] Suitable materials for producing porous materials are all materials that do not react with liquid coatings. When the porous material is an open-cell foam, the material from which the porous material is made may be any material that does not react with liquid coatings, may be a material that can be formed into an open-cell foam, and is preferably a polymer. Suitable polymers from which porous materials are made include, for example, polyolefins, particularly polyethylene or polypropylene, polyurethane, or melamine resin. Open-cell polymer foams made from polyurethane or melamine resin are particularly preferred as porous materials.
[0020] When the porous material is a felt, woven fabric, or nonwoven fabric, any material can be used as the fiber for making the felt, woven fabric, or nonwoven fabric to form a soft surface that does not abrade the material from the surface of the substrate. In this case, suitable fibers may be polymer fibers or natural fibers. Suitable polymers for fibers include, for example, polyolefins, polyurethanes, or polyamides. Suitable natural fibers include, for example, wool, cotton, linen, or flax.
[0021] If the porous material is a perforated elastic material, the elastic material may be, for example, synthetic rubber or natural rubber, silicone or leather.
[0022] In addition to the materials mentioned above, porous materials made of metal, glass, or ceramic, such as felt or nonwoven fabric made of metal or glass fibers, or sintered bodies made of metal or ceramic, can also be used. However, in this case, in order to avoid damage to the surface of the substrate, it is preferable to attach a small layer of a soft material, such as soft felt, nonwoven fabric, knitted or woven fabric, or alternatively, open-cell polymer foam, to the surface of the porous material, and the liquid coating is applied to the surface of the substrate via this.
[0023] In particular, if the liquid coating leaks out of the porous material due to pressure on the surface of the substrate, and no further liquid coating is released once the pressurization is terminated, it is advantageous to use an elastic, open-cell polymer foam that restores its original shape after the pressurization is terminated.
[0024] To continuously coat a very long sheet, a sufficient amount of liquid coating must be prepared. However, the porous material must not be supersaturated with the liquid coating, so that the liquid coating flows out of the porous material only when the surface of the substrate is in contact with the porous material. Saturation is achieved when the porous material can no longer accept any more liquid coating without seeping it out at any point on its surface. This requires that the liquid coating can be metered and supplied to the porous material again while the surface of the substrate is being coated. For this purpose, the porous material is preferably connected to a storage container in which the liquid coating is located. The liquid coating can then be supplied to the porous material by using a suitable metering device, such as a metering pump. Alternatively, it is also possible to simply allow the liquid coating to flow continuously, for example, under the action of gravity. For this purpose, a buffer container can be used, for example, above the porous material, and the buffer container is filled with liquid coating to a predetermined filling level. This maintains a nearly constant hydrostatic pressure as the liquid coating is transferred into the porous material. Furthermore, it is also possible to fill the connection point from the storage container where the liquid coating is stored to the porous material with an additional porous material, and guide the liquid coating through the connection line to the porous material by capillary force.
[0025] Placing a pad made of a porous material within a suitable trough has the advantage of avoiding dripping from the porous material when coating the underside. The trough can be made of any material that is inert to the liquid coating, such as metal, polymer, glass, or ceramic. To deliver the liquid coating into the porous material, a tube is placed below the trough, with an opening on its upper side and in fluid contact with an opening at the bottom of the trough. The liquid then flows from the tube into the trough through the tube and the trough opening. For this purpose, a passage may be provided connecting the tube and the trough opening, or the tube may be attached directly to the trough so that the tube and the trough opening are in the same position. In this case, the tube may be fixed to the trough by welding, soldering, or adhesive to achieve a liquid-tight connection and prevent the liquid coating from leaking between the tube and the trough.
[0026] To allow pressure to be applied to the porous material, the side walls of the trough have a height lower than the height of the uncompressed pad. In this context, the height of the pad corresponds to the portion extending perpendicular to the surface of the substrate being covered, the length corresponds to the portion extending laterally with respect to the direction of travel of the substrate, and the width corresponds to the portion extending laterally with respect to the direction of travel of the substrate. On the other hand, the length of the substrate or the surface of the substrate corresponds to the portion extending laterally with respect to the direction of travel of the substrate, and the width of the substrate or the surface of the substrate corresponds to the portion extending laterally with respect to the direction of travel of the substrate.
[0027] In particular, when the intention is to coat the surface of a substrate in a continuous process, it is even more preferable if the edges of the substrate to be coated, which extend laterally with respect to the coating direction, are parallel.
[0028] The surface of the pad that comes into contact with the surface of a substrate during application of a liquid coating may be a flat surface or may be curved. Furthermore, the surface may have, along the width of the pad, a convex portion that contacts the surface of the substrate during application of the liquid coating. The convex portion may, for example, have a circular, curved or triangular cross-section perpendicular to the surface of the substrate. For uniform application of a primer in a thin coating, it is only essential that the pad contacting the surface of the substrate is constant along the entire width of the surface of the substrate to be coated. Ideally, it is desirable that the pad has a uniform thickness along the entire width of the surface of the substrate to be coated.
[0029] When the surface of the substrate to be coated has a structure extending parallel to the traveling direction of the substrate during coating, for example when the substrate has a corrugated or zigzag surface structure, or when it has another surface structure with convex portions or concave portions extending parallel to the traveling direction of the substrate during the coating process, it is preferable that the pad comprises a structured surface having a structure corresponding to the structure of the surface of the substrate. In this way, during application of the primer, the entire structured surface of the pad is in contact with the surface of the substrate to be coated.
[0030] The apparatus for coating the surface of a substrate can be used, for example, in the manufacture of sandwich panels, or for applying an adhesive to a surface. When the apparatus is used in a manufacturing process for sandwich panels, the liquid coating is typically a primer for improving the adhesion of a foam layer on an outer sheet.
[0031] A method for manufacturing a sandwich panel comprising a first sheet, a second sheet, and a foam layer applied between the first sheet and the second sheet, (a) applying a primer to an inner surface of the first sheet, (b) applying a liquid reaction mixture comprising a reactant for producing a polymer and a blowing agent to the primer on the inner surface of the first sheet, wherein after application, the reaction mixture starts to react and expand, thereby forming a foam layer, (c) Applying a primer to the inner surface of the second sheet by a surface coating method, and (d) A method comprising supplying a second sheet such that the primer on the inner surface of the second sheet is placed in the foam layer, thereby forming a sandwich panel.
[0032] In the context of this invention, the terms “inner surface of the first sheet” and “inner surface of the second sheet” each refer to the surface facing inward of the sandwich panel and in contact with the foam layer. During the manufacturing process, the first and second sheets are typically supplied horizontally within a double belt. In this context, the first sheet is the lower sheet and the second sheet is the upper sheet; therefore, the inner surface of the first sheet is the top surface and the inner surface of the second sheet is the bottom surface.
[0033] When sandwich panels are used as facade members for buildings, it is preferable that at least one of the first sheet and the second sheet is made of metal, and if only one sheet is made of metal, the sheet made of metal is preferably the sheet that faces outward after assembly. In a preferred embodiment, both the first sheet and the second sheet are made of metal.
[0034] When the first and second sheets are manufactured from metal, the metals used are typically aluminum, steel, stainless steel, or copper. The use of steel or stainless steel is particularly preferred. The metal of the first and / or second sheets may or may not be coated on its outer surface (the surface facing outwards from the sandwich panel). Furthermore, the metal of the first and / or second layers can be pre-treated, for example, by corona treatment, plasma treatment, flame impingement, or other standard methods. In this case, different materials can be used for the first and second sheets. However, it is preferable to use the same material for the first and second sheets.
[0035] Depending on the use of the sandwich panel, in addition to sheet metal, metal films, polymer films, or organic sheets, such as multilayer composite films, can also be used as the first and second sheets of the sandwich panel. Furthermore, bitumen nonwoven fabric can also be used as the sheet material.
[0036] The first and second sheets, when manufactured from metal and used as facade members for buildings, typically have a thickness in the range of 0.25 to 1.5 mm. When steel is used as the material for the first and / or second sheets, it preferably has a thickness in the range of 0.25 to 0.88 mm, and particularly preferably in the range of 0.4 to 0.75 mm. Stainless steel sheets preferably have a thickness in the range of 0.3 to 0.9 mm, and particularly preferably in the range of 0.4 to 0.6 mm. Aluminum sheets preferably have a thickness in the range of 0.3 to 1.5 mm, and particularly preferably in the range of 0.5 to 0.8 mm, and copper sheets preferably have a thickness in the range of 0.3 to 1 mm, and particularly preferably in the range of 0.4 to 0.7 mm. The surfaces of the first and second sheets may have any structure, but preferably the surface is flat or has only a microstructure called so-called microprofilation. This means that the surface irregularities present as a result of the structure are preferably 2 mm or less in depth, and preferably 1 mm or less in depth. The structure may be present only on the outer surface of the first and / or second sheet, or on both the outer and inner surfaces.
[0037] Sandwich panels used for building facades can have any length and width that is conventional for sandwich panels. Generally, sandwich panels have a length of 2.5 to 30 m, preferably in the range of 3 to 24 m, and particularly in the range of 5 to 20 m. The width of the sandwich panel is preferably in the range of 0.5 to 1.25 m, and particularly in the range of 0.9 to 1.2 m.
[0038] To uniformly apply the primer to the inner surface of the second sheet, the pad preferably has a length equal to at least the width of the inner surface of the second sheet. However, the length of the pad is preferably longer than the width of the inner surface so that the pad extends beyond the width of the second sheet during primer application.
[0039] The foam layer in a sandwich structure is typically made from a rigid foam on an isocyanate substrate, such as polyurethane (PUR) foam, polyisocyanurate (PIR) foam, or poly(urethane-isocyanurate) foam (PU / PIR). For this purpose, the reaction mixture applied to the primer on the inner surface of the first sheet comprises reactants for producing polyurethane foam, polyisocyanurate foam, or poly(urethane-isocyanurate) foam. Such reaction mixtures are well known to those skilled in the art and are described, for example, in International Publication No. 2010 / 060864.
[0040] The primers applied to the inner surfaces of the first and second sheets are typically adhesives or binders, and are well known to those skilled in the art. Suitable primers are described, for example, in International Publication 2006 / 120234, European Patent Application Publication 2412526, International Publication 2010 / 060864, or International Publication 2015 / 155138. Particularly preferred is the primer being a one-component binder which is an isocyanate prepolymer having free isocyanate groups.
[0041] The same primer can be used on the inner surfaces of the first and second sheets, or different primers can be used on the inner surfaces of the first and second sheets. However, it is preferable to use the same primer on both the first and second sheets.
[0042] The primer used is preferably a one-component system that can be applied with a single pad. If a two-component primer or two different primers are intended to be applied to the inner surface of the second sheet, the two-component primer or two different primers are applied to the inner surface of the second sheet by applying the first component or first primer with the first pad and the second component or second primer with the second pad, so that the second component or second primer is applied on top of the first component or first primer. In this case, the mixing of the two different primers or two components is performed directly on the inner surface of the second sheet by applying the second primer or second component on top of the first primer or first component before the first primer or first component begins to cure. Furthermore, it is possible to make the primer coating on the inner surface of the second sheet thicker by applying the same primer with at least two pads arranged in series. However, in order to minimize the amount of foreign matter in the sandwich panel, it is generally preferable to apply the primer as thinly as possible and to have a thickness sufficient so that the primer remains liquid when it comes into contact with the expansive reaction mixture that forms the foam layer.
[0043] The thickness of the primer coating on the inner surface of the second sheet, and the thickness of the primer coating on the inner surface of the first sheet if a pad made of porous material is also used to apply the primer coating to the inner surface of the first sheet, can also be set by pressure, i.e., the pressure at which the porous material is pressed against the inner surfaces of the second sheet and / or the first sheet, the width of the porous material application, the type of material used as the porous material, the back pressure set by a pressure reducing valve when the primer is supplied to the porous material by a pump circuit, the pressure when the primer is supplied to the porous material by gravity, and / or the speed at which the inner surfaces of the first and / or second sheets pass through the porous material.
[0044] Sandwich panels can be manufactured in a continuous or discontinuous process.
[0045] To continuously manufacture sandwich panels, the first sheet is preferably supplied from a coil to an apparatus for applying a primer to the inner surface of the first sheet. The apparatus for applying the primer to the inner surface of the first sheet may be any apparatus known to those skilled in the art, for example, a rotating disk as described in International Publication 2006 / 120234, European Patent Application Publication 2412526, International Publication 2010 / 060864, or International Publication 2015 / 155138. However, in addition to such a rotating disk, any other suitable apparatus for applying the primer to the inner surface of the first sheet can be used. In addition to the well-known apparatus, the above-mentioned pads can also be used to apply the primer to the inner surface of the second sheet. In particular, if the first sheet is a profile sheet, and especially if the first sheet has a wavy or zigzag cross-sectional shape, or any cross-sectional shape with irregularities, it is preferable to apply the primer to the inner surface of the first sheet using the pad described above, i.e., a pad having a profiled surface corresponding to the inner surface profile of the first sheet, in order to achieve uniform coating over the entire inner surface of the first sheet.
[0046] After applying a primer to the inner surface of the first sheet, the reaction mixture for producing the foam layer is applied to the primer on the inner surface of the first sheet. Any suitable apparatus known to those skilled in the art can be used to apply the reaction mixture.
[0047] Typically, the first sheet is supplied horizontally to the apparatus for applying the primer and the apparatus for applying the reaction mixture. Thus, the primer and reaction mixture are applied from above to the inner surface that forms the upper side of the first sheet.
[0048] The second sheet is positioned above the first sheet and is preferably supplied horizontally from the coil. The primer is applied using the pad to the inner surface of the second sheet, facing downwards and opposite to the inner surface of the first sheet.
[0049] After being applied to the inner surface of the first sheet, the reaction mixture begins to react, and the foaming agent contained in the reaction mixture causes it to expand and form a foam. After applying the primer to the inner surface of the second sheet, the second sheet is moved toward the first sheet until the distance between the inner surfaces of the first and second sheets corresponds to the intended thickness of the foam layer. Due to the expansion of the reaction mixture, the foam stretches upward toward the inner surface of the second sheet, coming into contact with the primer, thereby providing a stable connection between the foam layer and the inner surface of the second sheet.
[0050] To avoid uneven thickness and roughness in the foam layer that would result in an uneven thickness in the sandwich panel, the first and second sheets are fed onto a double belt after the reaction mixture is applied, allowing the reaction and expansion of the reaction mixture to occur on the double belt. Furthermore, the double belt is used to transport the first and second sheets, and also after the reaction and foaming of the reaction mixture during the production of the sandwich panel.
[0051] Typically, each belt in a double belt has a link conveyor that guides it around rollers. To move the belts, at least one of the rollers on each belt is a driven roller. The link conveyors are arranged parallel to each other with spacing corresponding to the thickness of the sandwich panel being manufactured. While the reaction mixture expands to form a foam, the first sheet is pressed against the lower belt of the double belt and the second sheet against the upper belt of the double belt. The pressure on the belts ensures a consistent thickness for the sandwich panel. To avoid expansion of the sandwich panel after it leaves the double belt, the double belt is preferably of a length such that the reaction of the reaction mixture is complete and a rigid foam is formed when the sandwich panel leaves the double belt.
[0052] In the continuous process, after leaving the double belt, the manufactured sandwich panels are cut into pieces of a predetermined length.
[0053] When the sandwich panel is manufactured in a discontinuous process, the primer and reaction mixture are applied to the entire inner surface of the first and second sheets by moving a coating device, i.e., a pad made of porous material for applying the primer and a device for applying the reaction mixture, along the first sheet, and moving the primer coating device along the second sheet, thereby applying the primer to the entire inner surface of the first sheet, applying the reaction mixture on top of the primer applied to the inner surface of the first sheet, and then placing the second sheet in place to obtain the sandwich panel.
[0054] In addition to their use as facade components in commercial sectors, such as warehouses or industrial buildings, such as workshops, sports halls, department stores or assembly shops, sandwich components manufactured by the method of the present invention can be used as insulating panels, as walls or doors for cold storage or artificial climate chambers, or as walls or doors for truck bodies.
[0055] Embodiments of the present invention are shown in the drawings and will be described in more detail in the following description. [Brief explanation of the drawing]
[0056] [Figure 1] This is a schematic diagram of an apparatus for manufacturing sandwich components. [Figure 2] This figure shows a pump circuit for supplying a liquid coating to a coating device equipped with a pad made of porous material. [Figure 3] This is a three-dimensional view of the supply section of a coating device. [Figure 4] This is a cross-sectional view of the coating apparatus. [Figure 5] This figure shows a pad made from a porous material with a structured surface. [Figure 6] This figure shows a coating device for applying primer to the upper surface of a sheet. [Figure 7] This figure shows a coating device for applying primer to the underside of a sheet.
[0057] Figure 1 shows a schematic diagram of an apparatus for continuously manufacturing sandwich components.
[0058] Apparatus 1 for manufacturing sandwich panels includes a first coating device 3 for applying a primer to the inner surface 5 of a first sheet 7. In a continuous process, the first sheet 7 is typically fed from a coil into the apparatus 1 for manufacturing sandwich components. When this process is performed discontinuously, the first sheet 7 having the dimensions of the sandwich panel to be manufactured can be supplied to the apparatus 1 for manufacturing sandwich panels. By feeding the first sheet 7 downstream of the first coating device 3 at a constant speed, the primer is applied in a uniform coating.
[0059] A second coating apparatus 9 for applying the reaction mixture is located downstream of the first coating apparatus 3. The reaction mixture contains reactants that form a polymer and a foaming agent, so that a foam layer 11 is formed during the reaction. The reaction mixture is applied to the inner surface 5 of the first sheet 7 before the primer hardens, in order to stably bond the foam to the inner surface 5 of the first sheet 7.
[0060] Above the first sheet 7, the second sheet 13 is supplied to the apparatus 1 for manufacturing the sandwich panel. Since the first sheet 7 and the second sheet 13 are connected by a foam layer 11, the speed at which the second sheet 13 is fed is the same as the speed at which the first sheet 7 is fed.
[0061] A primer is applied by a liquid coating device 17 to securely bond the foam layer 11 to the inner surface 15 of the second sheet 13. Due to the expansion of the reaction mixture, the foam obtained from the reaction mixture comes into contact with the primer on the inner surface 15 of the second sheet 13. With respect to the first sheet, if the foam layer 11 comes into contact with the primer before the primer hardens, the foam layer 11 and the second sheet 13 are securely bonded.
[0062] A double belt 19 is positioned downstream of the first and second coating devices 3,9 and the coating device 17 for liquid coating in order to transport the first sheet 7 and the second sheet 13 and to produce a sandwich panel having a uniform thickness.
[0063] The double belt 19 has a first conveyor belt 21 below the first sheet 7 and a second conveyor belt 23 above the second sheet 13. During the production of the sandwich panel, the expanding foam presses the first sheet 7 against the first conveyor belt 21 and the second sheet 13 against the second conveyor belt 23. The conveyor belts prevent the foam from lifting the second sheet 13 above the distance between the first and second conveyor belts 21 and 23, thus ensuring a consistent thickness for the sandwich member. For this purpose, the lengths of the conveyor belts 21 and 23 are selected so that the first and second sheets 7 and 13 remain in contact with the conveyor belts until the reaction mixture hardens and a stable foam is produced.
[0064] To apply a uniform coating of primer to the inner surface of the second sheet 13, the liquid coating application device 17 has a pad made of a porous material that is pressed against the inner surface 15 of the second sheet 13.
[0065] In a continuous process, it is necessary to continuously supply primer to the liquid coating apparatus 17. Figure 2 shows the pump circuit for supplying primer to the liquid coating apparatus 17.
[0066] The pump circuit 25 for supplying liquid coating to the coating apparatus 17 has a storage container 27 in which the liquid coating is stored. From the storage container 27, the liquid coating is supplied to the coating apparatus 17 by a pump 29. Downstream of the coating apparatus 17, the circuit has a valve 31. The valve 31 sets the back pressure of the liquid coating in the circuit, and sets the amount of liquid coating in the porous material of the coating apparatus 17 and the amount of liquid coating applied to the surface of the substrate.
[0067] Figure 3 shows a three-dimensional view of the supply section of a liquid coating apparatus, and Figure 4 shows a cross-sectional view of the liquid coating apparatus including the supply section.
[0068] The supply unit for the liquid coating may have a tube 33 through which the liquid coating flows. The tube 33 may be part of a pump circuit, for example, as shown in Figure 2, when the liquid coating is supplied to the coating device 17 by such a pump circuit.
[0069] Tube 33 has an opening 35 on its upper side, through which the liquid coating can flow into a trough 37 located above the tube and connected to the opening 35 by a suitable passage 39. In addition to the passage 39 shown herein, it is also possible to connect the trough 37 and the tube 33 directly. When a passage 39 is used to connect the trough 39 and the tube 33, it is preferable that the passage has a cross-sectional shape corresponding to the cross-sectional shape of the opening 35 of the tube 33. To allow the liquid coating to flow further into the trough 37, the trough 37 has an opening 41 at its bottom. The cross-sectional shape of the opening 41 at the bottom of the trough 37 corresponds to the cross-sectional shape of the passage 39. Since the passage 39 is liquid-tightly attached to the bottom of the tube 33 and the trough 37, the liquid coating cannot leak.
[0070] If the passage 39 is not provided, the trough 37 is directly attached to the tube 33. In this case, it is preferable that the openings 35 and 41 have the same cross-sectional shape and are attached flush with the surface. Whether or not the trough 37 is attached to the tube 33 using the passage 39, a liquid-tight connection can be obtained, for example, by welding, bonding, or soldering.
[0071] Instead of the slot-shaped openings 35, 41 shown here, it is also possible to provide multiple openings in the tube 33 and / or at the bottom of the trough 37. In this case, if the trough 37 is attached to the tube 33 without a passage 39, it is preferable that one portion has slot-shaped openings and the other portion has a row of openings. In this case, after the trough is attached to the tube, the row of openings must be entirely within the cross-sectional area of the slots, and the slot-shaped openings must be surrounded with a weld seam, solder seam or adhesive to avoid leakage of the liquid coating.
[0072] To coat the surface of the substrate, the trough 37 includes a pad 43. The pad 43 is made of a porous material, and the liquid coating flows from the tube 33 through the passage 39 to the pad 43, and as soon as the surface of the substrate comes into contact with the surface 45 of the pad 43, the liquid coating is released from the pad 43 onto the surface of the substrate. A suitable mounting device 47 is provided to secure the pad 43 within the trough 37. The mounting device 47 is, for example, a bracket or clamp, which secures the pad 43 to the trough 37. However, any other mounting device other than a bracket or clamp can be used to secure the pad 43 within the trough 37. It is preferable that the pad 43 be removable from the trough 37 for replacement, for example, to clean the pad 43, or to remove a used pad.
[0073] Using a pad 43 to apply a liquid coating to the surface 49 of the substrate 51 has the advantage that a uniform coating layer can be applied even to surfaces 49 having structural components. This is illustrated exemplified in Figure 5 with respect to a surface having convex portions 53 and concave portions 55.
[0074] To uniformly apply the liquid coating, the pad has a surface 45 having a structure corresponding to the structure of the surface 49. This means that the surface 45 of the pad 43 has protrusions 57 where the surface 49 of the substrate 51 has recesses 55, and recesses 59 where the surface 49 of the substrate 51 has protrusions 53. If the surface 49 has a structure different from those shown herein, for example, a corrugated structure or a zigzag structure, the surface 45 of the pad 47 has the respective corrugated or zigzag structure.
[0075] Figure 6 shows an apparatus for applying a liquid coating to the upper surface of a substrate.
[0076] To apply a liquid coating to the upper surface of the substrate, the surface 45 of the pad 43 faces downward and is in contact with the upper surface 49 during coating. Using a porous material for the pad 43 has the advantage that after the surface 49 is separated from the surface 45 of the pad, the flow of the liquid coating stops and does not drip from the pad 43.
[0077] The liquid coating can be supplied to the pad 43 by a pump circuit as shown in Figure 2, or alternatively, by using a storage container 61 for the liquid coating positioned higher than the tube 33 and pad 43, as shown in Figure 6. In this case, the liquid coating flows into the tube 33 by gravity. Depending on the hydrostatic pressure of the liquid coating and the thickness and pore diameter of the pad 43, the liquid coating can be impregnated into the pad 43. However, after the liquid coating has impregnated the pad 43, excessive impregnation can be avoided by supplying only the amount of liquid coating that will be released when it is applied to the surface 49 of the substrate 51 to be coated.
[0078] Figure 7 shows an apparatus for applying a liquid coating to the underside of a substrate.
[0079] The coating apparatus 17 shown in Figure 7 differs from the embodiment shown in Figure 6, in which the liquid coating is applied to the surface 49 of the substrate 51 via the surface 45 of the pad 43 at the position of the surface 45 of the pad 43. In the embodiment shown in Figure 7, the surface 45 of the pad 43 faces upward, so that during the coating process, the surface 49 of the substrate to be coated is above the surface 45 of the pad. In this case, the liquid coating supplied into the tube 33 must have a sufficiently high pressure to completely permeate the pad 43. When the surface 49 to be coated is in contact with the surface 45 of the pad, the liquid coating is applied to the surface 49 of the substrate 51 by a specified pressure, or the substrate 51 is pressed against the surface 45 of the pad 43 by capillary force. To achieve a sufficiently high pressure, a pump circuit as shown in Figure 2 may be used, or alternatively, a storage container 61 containing the liquid coating as shown in Figure 7 may be used. This storage container provides a sufficiently high hydrostatic pressure because the surface of the liquid coating is positioned above the surface 45 of the pad.
Claims
1. An apparatus for applying a liquid coating to the surface (49) of a substrate (51), comprising a tube (33) for supplying the liquid coating and a pad (43) made of a porous material, wherein the tube (33) has at least one opening (35) extending parallel to the main axis of the tube (33), and / or the tube (33) has a plurality of openings arranged in a row parallel to the main axis of the tube (33), and the liquid coating can be supplied to the pad (43) through the openings. The apparatus comprises a metering device for supplying the liquid coating to the tube (33) at a predetermined pressure, the pad being located within a trough (37), the tube (33) being located below the trough (37), and the at least one opening (35) or the plurality of openings of the tube (33) being in fluid contact with openings on the lower surface of the trough so that the liquid coating can flow from the tube into the trough and uniformly permeate the pad (43).
2. The apparatus according to claim 1, wherein the porous material is an open-cell foam having a cell size with an average diameter in the range of 70 to 1500 μm.
3. The apparatus according to claim 1 or 2, wherein the pad (43) has a structured surface (45) having a structure corresponding to the structure of the surface (49) of the substrate (51), so that during the application of the liquid coating, the entire structured surface (45) of the pad (43) is in contact with the surface (49) of the substrate (51) to be coated.
4. The apparatus according to any one of claims 1 to 3, wherein the opening (35) is a slot parallel to the main axis of the tube (33), or the plurality of openings are arranged in rows parallel to the main axis of the tube (33).
5. The apparatus according to any one of claims 1 to 4, wherein the side wall of the trough (37) has a height lower than the height of the uncompressed pad (43).
6. A method for coating the lower surface of a substrate using the apparatus described in any one of claims 1 to 5, (i) In order to impregnate the pad (43) with the liquid coating, supply the liquid coating from the tube (33) through the at least one opening (35) to the trough (37), and (ii) Pass the surface (49) of the substrate (51) along the surface (45) of the pad (43) under a predetermined pressure so that the liquid coating is applied to the surface (49) of the substrate (51). Methods that include...
7. A method for manufacturing a sandwich panel comprising a first sheet (7), a second sheet (13), and a foam layer (11) applied between the first sheet (7) and the second sheet (13), (a) Apply a primer to the inner surface (5) of the first sheet (7), (b) A liquid reaction mixture containing reactants and a foaming agent for producing a polymer is applied to the primer on the inner surface (5) of the first sheet (7), and after application, the reaction mixture begins to react and expand, thereby forming the foam layer (11). (c) Applying a primer to the inner surface (15) of the second sheet (13) by the method described in claim 6, and (d) Supply the second sheet (13) such that the primer on the inner surface (15) of the second sheet (13) is placed on the foam layer (11), thereby forming the sandwich panel. Methods that include...
8. The method according to claim 7, wherein, in order to apply the primer to the inner surface (5) of the first sheet (7), the inner surface (5) of the first sheet (7) is passed over a pad (43) made of a porous material and impregnated with the primer, thereby coating the inner surface (5) of the first sheet (7) with the primer.
9. The method according to claim 7 or 8, wherein the first and second sheets (7, 13) are made of metal.
10. The method according to any one of claims 7 to 9, wherein the reaction mixture comprises a reactant for producing polyurethane foam, polyisocyanurate foam, or poly(urethane-isocyanurate) foam.
11. The method according to any one of claims 7 to 10, wherein the primer is an adhesive or binder.
12. The method according to any one of claims 7 to 11, wherein a primer comprising two components or two different primers is applied to the inner surface (15) of the second sheet (13) by applying the first component or the first primer with a first pad (43) and the second component or the second primer with a second pad (43) such that the second component or the second primer is applied on top of the first component or the first primer.
13. The method according to any one of claims 7 to 12, wherein the above method is carried out continuously.
14. The method according to claim 13, wherein, after applying the reaction mixture, the first and second sheets (7, 13) are supplied to a double belt (19), and the reaction and expansion of the reaction mixture occurs in the double belt (19).