METHOD FOR PRODUCE A REUSABLE CONCRETE FORMWORK PLATE AND CONCRETE FORMWORK PLATE

Description

[0001] The invention relates to a method for producing a reusable concrete formwork panel, in particular for exposed concrete, and a concrete formwork panel for multiple uses in concrete casting, in particular for exposed concrete.

[0002] On construction sites, formwork is required as an aid for a wide variety of concrete work. Current technology encompasses both very high-quality and correspondingly expensive formwork, as well as lower-quality and correspondingly inexpensive formwork.

[0003] High-quality formwork is typically system formwork used in conjunction with an assembly / fastening system and is usually made of coated plywood or coated solid wood panels. This high-quality formwork is designed for long-term and repeated use. However, its reuse is limited, typically to ten to fifteen times. The disadvantages of these formwork panels are their high price and lack of customizability, as they usually cannot be cut to a required size.

[0004] For example, a method for producing concrete formwork panels using melamine-impregnated kraft paper is already known from KR 2007 00 25 785 A, comprising as process steps first the production of liquid melamine resin and then the production of melamine-impregnated kraft paper. Subsequently, the melamine-impregnated kraft paper, a non-impregnated glass paper, a sheet and a phenol-impregnated kraft paper are stacked on top of each other and a stacked formwork panel is produced by thermal pressing.

[0005] From EP 3 480 030 A1, a method for producing an abrasion-resistant wood-based panel with a top and a bottom surface is already known, wherein at least one decorative layer, in particular a printed decoration, is provided on the top surface. In this method, at least one first resin layer is first applied to the at least one decorative layer on the top surface of the wood-based panel, then abrasion-resistant particles are uniformly sprinkled onto the first resin layer on the top surface of the wood-based panel, wherein the first resin layer on the top surface of the wood-based panel, containing the abrasion-resistant particles, is not dried after application.This is followed by the application of at least one second resin layer to the first, moist resin layer on the top side of the wood-based panel, which is provided with the abrasion-resistant particles, and finally the assembly of first resin layer and second resin layer on the top side of the wood-based panel is dried in at least one drying device.

[0006] The more affordable formwork panels are usually made of uncoated particleboard or oriented strand board (OSB). These are typically only suitable for single use and therefore often remain in place as so-called permanent formwork, for example, in the ground around foundations. However, these inexpensive but low-quality formwork panels have the disadvantage that attempts to remove them often result in demolding problems and damage, thus precluding reuse. Furthermore, swelling of the formwork panels typically occurs even during initial use, which not only prevents reuse but also creates an uneven, wavy texture on the concrete surface, making these formwork panels unsuitable for use with exposed concrete.

[0007] The invention is based on the objective of providing a method for producing a concrete formwork panel and a concrete formwork panel that allows for multiple uses and particularly cost-effective production, wherein the concrete formwork panel is also suitable for casting exposed concrete.

[0008] The problem is solved according to the invention by a method for producing a reusable concrete formwork panel according to claim 1 and by a concrete formwork panel for multiple uses in concrete casting according to claim 9. Advantageous embodiments are specified in the dependent claims.

[0009] In the inventive method for producing a reusable concrete formwork panel, particularly for exposed concrete, a particleboard or oriented strand board (OSB) with two face sheets and intermediate side surfaces is first provided. This is followed by the full-surface, opaque application of a liquid, two-component, water-based coating composition to at least one of the face sheets, preferably both, using a liquid process. One component of the coating composition is essentially a thermosetting resin, and the second component is a release agent. Finally, the applied coating composition is cured in a hot press under increased pressure and / or temperature to form a continuous coating on the particleboard or OSB.

[0010] The concrete formwork panel according to the invention for multiple uses in concrete casting, in particular for exposed concrete, has a base body made of a chipboard or an oriented strand board with two cover surfaces and side surfaces, and a coating of at least one of the cover surfaces, preferably both cover surfaces, made of a two-component, water-based coating composition, wherein one component of the coating composition is essentially formed from a thermosetting carrier resin and the second component is at least one release agent component, and wherein the coating is formed by pressing the coating composition onto the base body using a hot press for curing under increased pressure and / or increased temperature, and / or the coating is pressed into a surface of the base body.

[0011] It has surprisingly been shown that coating particleboard and oriented strand board (OSB) using a hot press and the coating composition according to the invention enables the cost-effective production of concrete formwork panels. The coating ensures good separation of the concrete formwork panel from the concrete during demolding after concrete casting, thus leaving the concrete formwork panel essentially undamaged. Furthermore, the coating repeatedly ensures a good surface quality of the cast concrete component, so that the concrete formwork panel according to the invention, despite its base being made of cost-effective (coarse) particleboard, can be reused multiple times for exposed concrete casting. This is made possible in particular by the use of a two-component, water-based coating composition that includes a release agent.

[0012] A concrete formwork panel is essentially a single panel of a formwork system into which fresh concrete is poured and shaped until it hardens sufficiently to support its own weight and other loads, as well as to maintain the shape defined by the formwork. The concrete formwork panel not only determines the shape of the concrete but also forms the contact surface with the liquid concrete, thus significantly influencing the concrete's surface finish. The concrete formwork panel is therefore designed to create formwork. Furthermore, the concrete formwork panel can be used with any setting and / or hardening building material, particularly concrete, but also, for example, with any type of screed.Therefore, its use is not limited exclusively to concrete, even though the concrete formwork panel is primarily designed for forming formwork for concrete elements and especially exposed concrete elements.

[0013] According to the invention, the concrete formwork panel is reusable, meaning that it can be used repeatedly for concrete casting and, particularly preferably, can be reused immediately after demolding for a subsequent concrete casting, especially without renewing the coating. Accordingly, the concrete formwork panel according to the invention is reusable and preferably at least three times, more preferably at least five times, and most preferably at least ten times for each concrete casting.

[0014] The concrete formwork panel can simply be a plate-shaped workpiece for arbitrary positioning as part of a concrete formwork, or it can have fastening elements permanently attached to it as part of a formwork system. According to the invention, however, the concrete formwork panel is formed exclusively from the base body or the particleboard or oriented strand board and / or has no further components or fastening elements, in order to be manufactured particularly cost-effectively and, if necessary, to be adapted to individual dimensions, for example by cutting.

[0015] According to the invention, the concrete formwork panel is based on a particleboard or an oriented strand board (OSB), with two face sheets and intermediate side surfaces, which thus form the basic body of the concrete formwork panel. Accordingly, the concrete formwork panel preferably has a substantially uniform thickness across its entire surface. The two face sheets are preferably the two opposing, large-area sides of the particleboard or OSB. One face sheet is preferably the top and the other the bottom of the particleboard or OSB. Preferably, the concrete formwork panel, particleboard, or OSB is rectangular and has four sides.

[0016] The particleboard or oriented strand board (OSB) can, in principle, have either an unaltered surface after production or a processed surface. However, it is preferred that the surface of the particleboard, and especially OSB, is sanded before the coating composition is applied. In the process according to the invention, a sanded particleboard or OSB is particularly preferred. Alternatively, however, an untreated and / or unsanded particleboard or OSB can also be used, thus enabling particularly cost-effective production of a concrete formwork panel. Furthermore, according to the invention, the concrete formwork panel—apart from the coating—is formed exclusively from the particleboard or OSB and / or contains no other materials besides the particleboard or OSB and the coating composition.Furthermore, it is preferred that each concrete formwork panel is made from exactly one chipboard or OSB board.

[0017] To prevent the particleboard or oriented strand board from swelling during contact with the liquid concrete, and to ensure reliable demolding and thus multiple uses, a coating is provided, consisting of a water-based coating composition. A water-based coating composition is defined as a composition with water as the main solvent and / or a hydrophilic and / or water-soluble composition.

[0018] According to the invention, the coating composition is applied in liquid form to at least one of the surface surfaces. Accordingly, the coating composition is generally liquid, with a flowable coating composition being preferred. The coating composition is applied to the surface to be coated, in particular both surface surfaces, completely and opaquely, so that a closed, complete and / or smooth surface coating is preferably obtained after curing.

[0019] The application of the two-component coating composition can be carried out in one or more layers. A single application is generally sufficient. However, two or more applications are also possible, preferably with intermediate drying between applications. Intermediate drying can be achieved by applying any type of heat or by irradiation. Convection drying, particularly with heated air, and / or IR irradiation are preferred. Intermediate drying using a heated roller or a heated surface or rail is also conceivable.

[0020] According to the invention, the coating composition is formed from at least two components, each of which can contain any number of constituents. In principle, however, the two components of the coating composition are completely miscible and / or form a homogeneous, non-segregating composition after mixing. Preferably, each of the two components is individually permanently stable in storage and, more preferably, each is a completely independent coating agent.

[0021] Alternatively, at least one component can be merely an auxiliary material or a mixture of several auxiliary materials. Furthermore, it is conceivable that one of the components is solid, and in particular powder form. Generally, however, it is preferred that at least one of the two components is liquid. It is also preferred that the coating composition and / or one of the components, and particularly preferably each of the two components of the coating composition, is a primer coating.

[0022] According to the invention, the first component comprises a thermosetting carrier resin, which is therefore fundamentally thermally curable. The first component can consist exclusively or substantially of the carrier resin or may contain any number of other substances. Preferably, however, the first component is composed of at least 60%, more preferably at least 80%, and most preferably at least 95% of the carrier resin or of carrier resin in an aqueous solvent. The first component also preferably comprises a film-forming powder, in particular at least one thermosetting resin, and is most preferably such a powder. The powder or the thermosetting carrier resin is preferably readily dispersible in water.

[0023] The second component is a release agent. This release agent is designed to facilitate easy separation of the hardened concrete from the surface of the coated concrete formwork panel. Accordingly, the release agent supports demolding without damaging the concrete formwork panel. For this purpose, the release agent is preferably permanently integrated into the coating composition and / or uniformly distributed within the coating. Therefore, the release agent is not merely a material layer temporarily applied to the surface of the coating composition. Furthermore, it is preferred that the second component of the coating composition and / or the release agent component are also fully cured within the coating.The second component is preferably water-dilutable.

[0024] The second component is preferably liquid, and the first component is particularly preferably readily and / or homogeneously dispersible in the second component or, alternatively, soluble therein. In principle, the two components of the coating composition can be mixed together in any ratio, with a mass ratio of the first component to the second component preferably being between 1:3 and 1:1, particularly preferably between 2:5 and 2:3, most preferably between 4:7 and 4:10, and most preferably approximately 1:2. According to the invention, after application of the coating composition, curing takes place to form a closed coating on the particleboard or on the oriented strand board. According to the invention, curing is carried out thermally, and particularly preferably essentially entirely thermally, although in principle any curing method, for example by means of UV radiation, is also conceivable.The thermal curing of the applied coating composition can, in principle, be achieved by any heat input and / or by means of radiation, in particular IR radiation. According to the invention, this is carried out in a hot press and / or by means of heated rollers and / or by means of heated rails or surfaces. In principle, several curing steps, even using different methods, are conceivable, although a single-step curing process is preferred.

[0025] According to the invention, a final thermal curing of the coating composition takes place in a hot press, and thus under elevated temperature and / or pressure. After curing, the coating is firmly bonded to the particleboard or oriented strand board, with the coating being pressed at least onto the surface and preferably also into the surface of the substrate. Pressing into the surface initially means simply that the coating was cured under pressure or during a pressing process, thereby forcing the coating composition onto the surface and into any surface defects and irregularities, such as depressions, cracks, and / or unevenness, thus achieving particularly good adhesion and a smooth surface of the coating, despite any surface defects and irregularities that may be present.Furthermore, it is also conceivable that at least part of the coating composition is pressed into a near-surface layer of the particleboard or oriented strand board, thus creating a particularly strong bond between the coating and the material surface.

[0026] In principle, the concrete formwork panel can be produced directly in the hot press without any additional inserts, such as press plates, separating plates, and / or separating films. However, by using a textured press plate, textures such as wood grain, stone structures, or the like can be created in the concrete. This can visually enhance the concrete surface. One side of the concrete formwork panel can be pressed without a press plate or with a press plate with a completely smooth surface, and / or the other side can be pressed with a textured press plate, so that at least one of the two sides has a texture that can be transferred to the concrete component. Preferably, both sides have different surface textures, so that optionally a smooth concrete surface and a textured concrete surface are possible.one of two possible structured concrete surfaces can be created.

[0027] A preferred embodiment of the inventive method for producing a reusable concrete formwork panel provides that the curing of the applied coating composition takes place in a short-cycle press, thereby enabling particularly fast and high-quality production. Accordingly, the hot press is preferably a short-cycle press and / or not a veneer press. Furthermore, the curing or pressing in the hot press, particularly the short-cycle press, preferably takes place without a release layer or film, which simplifies the pressing process and makes it more economical.

[0028] The curing of the applied coating composition can, in principle, be carried out for any duration, at any pressure, and at any temperature. In a preferred embodiment, the curing of the applied coating composition takes place over a duration, in particular a pressing time, of between 10 s and 120 s, preferably between 15 s and 60 s, particularly preferably between 20 s and 40 s, and most preferably of about 30 s. Additionally or alternatively, the curing of the applied coating composition takes place at a temperature, in particular a pressing temperature, of between 150 °C and 250 °C, preferably between 175 °C and 225 °C, particularly preferably between 190 °C and 210 °C, and most preferably at about 200 °C.Additionally or alternatively, the applied coating composition is cured under pressure, in particular a pressing pressure, between 25 kg / cm² < (2.45 MPa) and 75 kg / cm² < (7.35 MPa), preferably between 40 kg / cm² < (3.9 MPa) and 60 kg / cm² < (5.9 MPa), particularly preferably between 45 kg / cm² < (4.4 MPa) and 55 kg / cm² < (5.4 MPa) and most preferably at about 50 kg / cm² < (4.9 MPa).

[0029] The inventive method for producing a reusable concrete formwork panel provides that the coating composition is applied using a roller application system with at least one application roller, thus enabling a particularly simple, fast, and uniform application. Furthermore, application using more than one roller is also conceivable, for example, with two rollers arranged consecutively. Generally, however, it is preferred that the application is carried out exclusively using one or more rollers. In particular, the application is carried out using one or more roller coating units. In principle, however, another application method, for example, spraying, using one or more rollers individually or in combination, is also conceivable.

[0030] The application quantity can initially be chosen arbitrarily; however, an application quantity that is too low will result in insufficient reusability of the concrete formwork panel, while an application quantity that is too high can lead to reduced stability of the coating and also unnecessarily increase production costs. Accordingly, a preferred embodiment of the method according to the invention provides that the coating composition is applied in a quantity between 100 g / m² and 300 g / m², preferably between 150 g / m² and 250 g / m², particularly preferably between 200 g / m² and 240 g / m², and most preferably at approximately 220 g / m².

[0031] In an advantageous embodiment of the method according to the invention, the coating composition is applied at least to both face surfaces of the particleboard or the oriented strand board (OSB) and preferably also to the side surfaces of the particleboard or OSB. Particularly preferred is a complete and / or all-around coating of the surface of the concrete formwork panel, so that swelling or a bond with the concrete that can only be broken by damaging the concrete formwork panel is reliably prevented. Generally, it is preferred that all surfaces of the concrete formwork panel intended for contact with liquid and hardening concrete are provided with a coating.

[0032] In general, it is particularly positive that the concrete formwork panels can be recycled after use. However, a small amount of coating material applied relative to the mass of the panels, or the mass of the particleboard or oriented strand board, can lead to minor problems when reusing the recycled material for the production of wood-based materials, especially after shredding.

[0033] Finally, a preferred embodiment of the inventive method provides that the two components of the coating composition are each independent and individually usable coating compositions and are mixed together in a fixed ratio, in particular a mass or volume ratio, before application. The mixing preferably takes place immediately before the application of the coating composition. Independent and individually usable coating compositions are understood to mean that neither component contains a component that is absolutely necessary for forming a coating with the other component. Accordingly, it is preferably possible that a coating can be formed with each of the two components of the two-component coating composition, although this coating then does not possess the properties or characteristics of the inventive method.does not possess the suitability according to the invention for multiple uses as a concrete formwork panel.

[0034] A preferred embodiment of the concrete formwork panel is one in which the thermosetting carrier resin comprises, and preferably is, a melamine resin. However, it is also conceivable to use a condensation resin, in particular an aminoplast such as a melamine-formaldehyde resin, a benzoguanamine resin, or a urea-formaldehyde resin, or a phenolplast such as a phenol-formaldehyde resin, either individually or in a mixture, as the carrier resin. Additionally or alternatively, a thermoplastic synthetic resin such as diphenylmethane diisocyanate (PMDI), methylenediphenyl diisocyanate (MDI), also in emulsified form as eMDI, or polyurethane, either individually or in a mixture, can also be used as the carrier resin.

[0035] Furthermore, a concrete formwork panel is preferred in which the release agent component contains a release agent and, in particular, a hydrophobizing agent, and is most preferably a hydrophobizing agent itself. In addition, the release agent component can also be a complete coating material that acts as a release agent or as a release agent component. Additionally or alternatively, it is also preferred that the release agent component hydrophobizes the coating formed from the coating composition, i.e., imparts hydrophobic properties, in particular surface properties, to the coating. Additionally or alternatively, the release agent component can increase the contact angle between the coating and the liquid concrete and / or decrease the wettability.

[0036] Exemplary embodiments of the manufacturing process according to the invention, as well as of concrete formwork panels and their repeated use, are explained in more detail below. Example 1 - Coating of a sanded oriented strand board

[0037] A sanded oriented strand board (OSB) measuring 2800 x 2060 x 28 mm was coated on both sides and the top surfaces in a production line with roller coating units, applying a coating of approximately 220 g / m². The coating composition consists of two water-based components that are mixed immediately before application. Each component is a separate coating or primer composition, with one component acting as a release agent. The coating composition is a mixture of 12 kg Trollon Activator 2204 Yellow and 6 kg Trollon Carrier 1400.

[0038] After mixing the two components of the coating composition, a single application was carried out on a first series of concrete formwork panels, and a double application was carried out on a second series of concrete formwork panels with intermediate drying by means of circulating air.

[0039] The coated concrete formwork panels were then cured in a short-cycle press for a pressing time of 30 seconds at a pressing temperature of 200 °C and a pressing pressure of 50 kg / cm². The concrete formwork panels detached easily from the press plates and could be transported from the short-cycle press by the infeed / outfeed carriage. Furthermore, the use of a separating layer, in particular a separating film, was not necessary.

[0040] Additional tests with a chipboard have shown that a concrete formwork panel based on a chipboard instead of a oriented strand board can also be produced using the same parameters. Example 2 - Coating of an unsanded oriented strand board

[0041] An unsanded oriented strand board (OSB) measuring 2800 x 2060 x 28 mm was coated on both sides and the top surfaces in a production line with roller coating units, applying a coating of approximately 220 g / m². The coating composition consists of two water-based components that are mixed immediately before application. Each component is a separate coating or primer composition, with one component acting as a release agent. The coating composition is a mixture of 12 kg Trollon Activator 2204 Yellow and 6 kg Trollon Carrier 1400.

[0042] After mixing the two components of the coating composition, a single coat was applied to the first batch of concrete formwork panels, and a second batch received two coats with intermediate drying by circulating air. Despite the release agent still being present on the surface, the coating result was surprisingly similar to that of embodiment 1.

[0043] The coated concrete formwork panels were then cured in a short-cycle press for a pressing time of 30 seconds at a pressing temperature of 200 °C and a pressing pressure of 50 kg / cm². The concrete formwork panels detached easily from the press plates and could be transported from the short-cycle press by the infeed / outfeed carriage. Furthermore, the use of a separating layer, in particular a separating film, was not necessary. Here again, a similar result to that of embodiment 1 was observed.

[0044] Additional tests with a chipboard have shown that a concrete formwork panel based on a chipboard instead of a oriented strand board can also be produced using the same parameters. Example 3 - minimal coating of a chipboard

[0045] A sanded oriented strand board (OSB) measuring 2800 x 2060 x 28 mm was coated on both sides and the face sides with a coating quantity of approximately 150 g / m² in a production line with roller coating units. The coating composition corresponded to that in the first embodiment. A single application was carried out at a high application speed to allow for the formation of individual coating defects.

[0046] Afterwards, the coated concrete formwork panels were cured again in a short-cycle press for a pressing time of 30 seconds at a pressing temperature of 220 °C and a pressing pressure of 50 kg / cm². Example 4 - Concrete formwork experiment

[0047] From the coated concrete formwork panels produced in embodiments 1, 2 and 3, cut pieces were produced from which concrete formwork was then manufactured, each measuring 300 x 200 x 200 mm (L x W x D).

[0048] These molds were each filled with commercially available screed concrete, the screed was allowed to harden, and then the screed element was removed. The ease of demolding, the thickness of the concrete coating on the surface, and how easily these residues could be brushed off were all assessed. This procedure was repeated a total of seven times for each mold.

[0049] For all the concrete formwork panels examined, only a negligible deterioration in demolding and brushing effort was observed. As in the other areas, no significant swelling or coating delamination was visible at the defects from embodiment 2. No wavy defects or other reductions in surface quality were discernible on the concrete element either.

Claims

1. Method for manufacturing a concrete formwork board for multiple use, in particular for exposed concrete, comprising the steps of: - providing particleboard or coarse particleboard that has two cover sides and lateral surfaces, - all-over and opaque applying a liquid, water-based, two-component coating composition to at least one of the cover sides of the particleboard or coarse particleboard , - wherein the one component of the coating composition is essentially formed from a thermohardening carrier resin and the second component is at least one release agent component, and - wherein the application of the liquid coating composition to at least one of the cover sides of the particleboard or coarse particleboard is carried out by means of a roller application system with at least one application roller , and finally - curing the applied coating composition in a hot press to form a closed coating on the particleboard or coarse particleboard, wherein - the concrete formwork board, apart from the coating, is formed exclusively from the particleboard or coarse particleboard and / or does not have any materials other than the particleboard or coarse particleboard and the material of the coating composition.

2. Method for manufacturing a concrete formwork board for multiple use according to claim 1, characterized in that the applied coating composition is cured in a short cycle press.

3. Method for manufacturing a concrete formwork board for multiple use according to claim 1 or 2, characterized in that the applied coating composition is cured over a period of time, in particular a pressing time, of between 15 s and 60 s.

4. Method for manufacturing a concrete formwork board for multiple use according to at least one of the preceding claims, characterized in that the applied coating composition is cured at a temperature, in particular a pressing temperature, between 175 °C and 225 °C.

5. Method for manufacturing a concrete formwork board for multiple use according to at least one of the preceding claims, characterized in that the applied coating composition is cured at a pressure, in particular a pressing pressure, between 40 kg / cm2and 60 kg / cm2.

6. Method for manufacturing a concrete formwork board for multiple use according to at least one of the preceding claims, characterized in that the coating composition is applied in an amount between 150 g / m2 and 250 g / m2.

7. Method for manufacturing a concrete formwork board for multiple use according to at least one of the preceding claims, characterized in that the coating composition is carried out on at least both cover sides of the particleboard or coarse particleboard.

8. Method for manufacturing a concrete formwork board for multiple use according to at least one of the preceding claims, characterized in that the two components of the coating composition are each independent and individually usable coating compositions and are mixed together in a fixed ratio before applying the coating.

9. Concrete formwork board for multiple use in concrete casting, in particular for exposed concrete, with - a main body made of particleboard or coarse particleboard, which has two cover sides and lateral surfaces, - a coating on at least one of the cover sides consisting of a two-component water-based coating composition, - wherein the one component of the coating composition is essentially formed from a thermohardening carrier resin and the second component is a release agent component, and - the coating is formed by pressing the coating composition onto the surface using a hot press to cure it and / or the coating is pressed into a surface of the main body, characterized in that - apart from the coating, the concrete formwork board is formed exclusively from the particleboard or coarse particleboard and / or does not have any materials other than the particleboard or coarse particleboard and the material of the coating composition .

10. Concrete formwork board according to claim 9, characterized in that the thermohardening carrier resin is a melamine resin.

11. Concrete formwork board according to claim 9 or 10, characterized in that the release agent component makes the coating formed from the coating composition hydrophobic and / or the second component contains a hydrophobizing agent as the release agent component.