Method for manufacturing a reusable concrete formwork board, and concrete formwork board

Abstract

The invention relates to a method for producing a reusable concrete formwork board and to a concrete formwork board for repeated use in concrete casting. In order to provide a method for producing a concrete formwork board, as well as a concrete formwork board itself, which allow for multiple uses and particularly cost-effective manufacturing, the concrete formwork boards also being suitable for casting fair-faced concrete, according to the invention: firstly, a chipboard or an oriented strand board having two top sides and side faces is provided; and then a two-component, water-based coating composition in liquid form is applied to at least one of the top sides, one component of the coating composition comprising a heat-curable carrier resin and the second component comprising at least one release agent component. Finally, the applied coating composition is cured in a hot press to form a closed coating on the chipboard or oriented strand board.

Description

[0001] Description

[0002] METHOD FOR PRODUCING A MULTI-USE

[0003] CONCRETE FORMWORK PANEL AND CONCRETE FORMWORK PANEL

[0004] The invention relates to a method for producing a multi-use concrete formwork panel, in particular for exposed concrete, and to a concrete formwork panel for multiple use in concrete casting, in particular for exposed concrete.

[0005] Formwork is required as an aid for a wide variety of concrete projects on construction sites. State-of-the-art formwork includes both very high-quality and correspondingly expensive forms, as well as lower-quality and correspondingly inexpensive forms.

[0006] 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. These high-quality formwork panels are designed to be used for as long as possible and for as many times as possible. However, their reuse is limited, typically ten to fifteen times. The disadvantages of these formwork panels are their high price and their lack of customization, as they usually cannot be cut to the required size.

[0007] The more cost-effective formwork panels are usually uncoated chipboard or coarse particle board. These can usually only be used once and therefore often remain in the building as so-called permanent formwork, for example, in the ground near foundations. However, these cost-effective but low-quality formwork panels have the disadvantage that attempts to remove the formwork panels lead to demolding problems and damage to the formwork panels, thus precluding reuse. Furthermore, the formwork panels typically swell upon first use, which, on the one hand, virtually rules out reuse and, on the other hand, creates an uneven, wavy structure on the concrete surface, making these formwork panels unsuitable for use in exposed concrete.In addition, these simple formwork panels often do not have edge sealing, which also typically makes reuse impossible. With higher-quality formwork panels, however, edge sealing is either unnecessary due to the significantly better substrate material (plywood, wood), or high-quality metal tongue-and-groove systems are used, particularly frequently in so-called system formwork, which again leads to increased manufacturing costs.

[0008] The invention is based on the object of providing a method for producing a concrete formwork panel and a concrete formwork panel which enable multiple use and particularly cost-effective production, wherein the concrete formwork panel is also suitable for casting exposed concrete.

[0009] The object is achieved according to the invention by a method for producing a multi-use concrete formwork panel according to claim 1 and by a concrete formwork panel for multiple use in concrete casting according to claim 13. Advantageous further developments are specified in the dependent claims, wherein features relating directly to the method also apply to the concrete formwork panel and features described with regard to the concrete formwork panel are simultaneously also features of the method.

[0010] In the method according to the invention for producing a reusable concrete formwork panel, in particular for exposed concrete, a chipboard or a coarse particle board having two facing sides and side surfaces located therebetween is first provided, followed by application of a two-component, water-based coating composition by a liquid process to at least one of the facing sides, preferably to both facing sides, wherein one component of the coating composition has a thermosetting carrier resin and is in particular essentially formed therefrom, and the second component comprises at least one release agent component and is preferably a release agent component. Finally, the applied coating composition is cured in a hot press under increased pressure and elevated temperature to form a continuous coating on the chipboard or the coarse particle board.

[0011] The concrete formwork panel according to the invention for multiple use in concrete casting, in particular for exposed concrete, has a base body made of a chipboard or a coarse chipboard with two cover sides and side surfaces and a coating of at least one of the cover sides, preferably both cover sides, made of a two-component water-based coating composition, wherein one component of the coating composition has a thermosetting carrier resin and is in particular essentially formed therefrom and the second component comprises at least one release agent component, and wherein the coating is formed by pressing on the coating composition by means of a hot press for curing under increased pressure and elevated temperature and / or the coating is pressed into a surface of the base body.

[0012] It has surprisingly been found that coating chipboard and coarse particle board using a hot press and the coating composition according to the invention enables the cost-effective production of concrete formwork panels. The coating enables good separation of the concrete formwork panel from the concrete during demolding after concrete casting, and the concrete formwork panel accordingly remains essentially undamaged. Furthermore, the coating repeatedly enables a good surface quality of a cast concrete component, so that the concrete formwork panel according to the invention can be used multiple times for exposed concrete casting despite the base body made of a cost-effective (coarse) particle board. This is made possible in particular by the use of a two-component, water-based coating composition containing a release agent component.

[0013] A concrete formwork panel is essentially a single formwork panel into which fresh concrete is poured and thus shaped until it solidifies and hardens sufficiently to support itself 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 surface quality of the concrete. The concrete formwork panel is therefore intended to form a 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 screed.The use is therefore not limited exclusively to concrete, even if the concrete formwork panel is primarily designed to form formwork for concrete elements and in particular exposed concrete elements.

[0014] 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, in particular without renewing the coating. Accordingly, the concrete formwork panel according to the invention is reusable and can preferably be used at least three times, particularly preferably at least five times, and most preferably at least ten times for each concrete casting.

[0015] The concrete formwork panel can be simply a plate-shaped workpiece for arbitrary securing as part of a concrete formwork or, as part of a formwork system, can have permanently arranged fastening elements. Preferably, however, the concrete formwork panel according to the invention is formed exclusively from the base body or the chipboard or coarse particle board and / or has no further components or fastening elements in order to be able to be manufactured particularly cost-effectively and, if necessary, also to a customized size, for example by cutting. A particularly advantageous feature is that (coarse) particle boards are typically manufactured in a width of up to 2800 mm. This allows all common concrete formwork formats to be manufactured with minimal waste.

[0016] According to the invention, the concrete formwork panel is based on a chipboard or a coarse particle board, also referred to as OSB (Oriented Strand Board), with two cover sides and side surfaces in between, which thus forms the base body of the concrete formwork panel. Accordingly, the concrete formwork panel preferably has a substantially uniform thickness or material strength over the entire surface. The two cover sides are preferably the two opposite, large-area sides of the chipboard or the coarse particle board. Accordingly, one cover side is preferably a top side and the other cover side is a bottom side of the chipboard or the coarse particle board. Preferably, the concrete formwork panel or the chipboard or the coarse particle board is rectangular and accordingly has four side surfaces.

[0017] The chipboard or the coarse particle board can, in principle, have either an unchanged surface after production of the board or a processed surface. However, it is preferred that the surface of the chipboard, and in particular of a coarse particle board, is sanded before applying the coating composition. Particularly preferably, a sanded chipboard or coarse particle board is provided in the method according to the invention. Alternatively, however, a non-post-treated and / or unsanded chipboard or coarse particle board can also be used, thus enabling a particularly favorable production of a concrete formwork panel. Furthermore, it is preferred that the base body or the concrete formwork panel - apart from the coating - is formed exclusively from the chipboard or the coarse particle board and / or comprises no other materials than the chipboard or the coarse particle board and the material of the coating composition.

[0018] Furthermore, it is preferred that each concrete formwork panel be formed from a single chipboard or coarse particle board. A chipboard is preferably formed exclusively from chip material. Accordingly, a coarse particle board is preferably formed exclusively from coarse particle material. In principle, however, it is also conceivable for the concrete formwork panel to be formed not from a pure chipboard or a pure coarse particle board, but from a multi-layer hybrid board, wherein preferably at least one layer is a chipboard layer or a coarse particle board layer, and particularly preferably the entire hybrid board is formed exclusively from chipboard and coarse particle layers.Most preferably, a hybrid board has a coarse chip layer as a middle layer and at least one chip layer as a cover layer and in particular two cover layers of chip material on both sides, so that the hybrid board has the appearance and surface of a chipboard and, due to the middle layer of coarse chips, has the advantageous strength and rigidity of a coarse chipboard.

[0019] To prevent the particleboard or coarse particleboard from swelling during contact with the liquid concrete, as well as to ensure safe demolding and thus multiple use, a coating consisting of a water-based coating composition is provided. A water-based coating composition is understood to be a composition with water as the primary solvent and / or a hydrophilic and / or water-soluble composition.

[0020] According to the invention, the coating composition is applied using a liquid process to at least one of the cover sides. Accordingly, the coating composition is generally liquid or at least pasty, with a flowable coating composition being preferred. The coating composition is preferably applied to the surface to be coated, in particular to both cover sides, over the entire surface and / or covering it, so that a closed, complete, and / or surface-smooth coating is also preferably obtained after curing.

[0021] The two-component coating composition can be applied in either a single or multiple coats. A single coat is generally sufficient. However, two or more coats are also conceivable, with intermediate drying preferably occurring between two coats. Intermediate drying can generally be achieved by any heat application or by irradiation. Circulating air drying, particularly with heated air, and / or IR irradiation is preferred. Intermediate drying using a heated roller or a heated surface or rail is also conceivable.

[0022] The coating composition can initially consist of any number of constituents, wherein the coating composition is formed according to the invention from at least two components, wherein each of the two components can have any number of constituents. In principle, however, the two components of the coating composition are fully miscible and / or form a homogeneous, non-segregating composition after mixing. Each of the two components is preferably individually permanently stable in storage and particularly preferably each is a completely independently usable coating agent. Alternatively, however, at least one component can be merely an auxiliary substance or a mixture of several auxiliary substances. It is also conceivable for one of the components to be solid and in particular in powder form. In general, however, it is preferred for at least one of the two components to be liquid.Furthermore, it is 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.

[0023] According to the invention, the first component comprises a thermosetting carrier resin, which is thus fundamentally thermally curable. The first component can be formed exclusively or substantially from the carrier resin or can contain any desired number of other substances. Preferably, however, the first component is formed to at least 60%, particularly preferably to at least 80%, and very particularly preferably to at least 95% from the carrier resin or from carrier resin in an aqueous solvent. Likewise preferably, the first component comprises a film-forming powder, in particular of at least one thermosetting synthetic resin, and particularly preferably the first component is such a powder. The powder or the thermosetting carrier resin is preferably readily dispersible in water.

[0024] According to the invention, the second component comprises or is a release agent component. The release agent component is intended to enable easy separation of the hardened concrete from the surface of the coated concrete formwork panel when the coating is cured. Accordingly, the release agent component supports demolding without damaging the concrete formwork panel. For this purpose, the release agent component is preferably permanently incorporated into the coating formed from the coating composition and / or evenly distributed within the coating. Accordingly, the release agent component is not merely a layer of material temporarily applied to the surface of the coating formed from the coating composition.It is also preferred that the second component of the coating composition and / or the release agent component in the coating be fully cured. Furthermore, the second component is preferably water-dilutable.

[0025] Likewise, the second component is preferably liquid, and particularly preferably, the first component is 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 desired 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 especially preferably approximately 1:2.

[0026] According to the invention, after the coating composition has been applied, curing takes place to form a continuous coating on the chipboard or on the coarse particle board. Curing is preferably carried out at least partially thermally and particularly preferably essentially completely thermally, although any curing method, for example by means of UV radiation, is also conceivable. The thermal curing of the applied coating composition can in principle take place by any heat input and / or by means of radiation, in particular IR radiation. This preferably takes place in a hot press and / or by means of heatable rollers and / or by means of heatable rails or surfaces. In principle, several curing steps, even using different methods, are conceivable, although single-step curing is preferred.

[0027] According to the invention, however, it is provided that a final thermal curing of the coating composition takes place in a hot press and thus under elevated temperature and increased pressure. After curing, the coating is then firmly bonded to the chipboard or the coarse particle board, wherein the coating is pressed at least onto the surface and preferably also into the surface of the base body. Pressing into the surface is initially understood simply to mean that the coating has been cured under pressure or during a pressing process and that the coating composition has thereby been pressed onto the surface as well as into surface defects and unevenness, such as depressions, cracks and / or unevenness of this surface, so that at the same time particularly good adhesion and a smooth surface of the coating are achieved, despite any surface defects and unevenness that may be present.In addition, it is also conceivable that a part of the coating composition is pressed into at least one material layer of the chipboard or coarse chipboard close to the surface, thus creating a particularly strong bond between the coating and the material surface.

[0028] In principle, the concrete formwork panel can be produced directly in the hot press without any additional plates inserted, such as press plates, separating plates and / or separating films. By using a structured press plate, however, structures such as wood grain, stone structures or the like can also be created in the concrete. This can visually enhance the concrete surface. In principle, 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 another side of the concrete formwork panel can be pressed with a structured press plate, so that at least one of the two sides has a structure for transferring to the concrete component. Preferably, both sides have a different surface structure, so that either a smooth concrete surface or a structured concrete surface orone of two possible structured concrete surfaces can be created.

[0029] A preferred embodiment of the method according to the invention for producing a reusable concrete formwork panel provides for the curing of the applied coating composition in a short-cycle press, which enables particularly fast and, at the same time, particularly 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, in particular the short-cycle press, preferably takes place without a release layer or release film, which simplifies the pressing process and at the same time makes it more economical.

[0030] The curing of the applied coating composition can in principle take place with any suitable duration, any suitable pressure and any suitable 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 very particularly 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, between 150 °C and 250 °C, preferably between 175 °C and 225 °C, particularly preferably between 190 °C and 210 °C and very particularly preferably at about 200 °C. Additionally or alternatively, the curing of the applied coating composition takes place at a pressure, in particular a pressing pressure, between 25 kg / cm 2(2.45 MPa) and 75 kg / cm 2 (7.35 MPa), preferably between 40 kg / cm 2 (3.9 MPa) and 60 kg / cm 2 (5.9 MPa), particularly preferably between 45 kg / cm 2 (4.4 MPa) and 55 kg / cm 2 (5.4 MPa) and most preferably at about 50 kg / cm 2 (4.9 MPa).

[0031] In an advantageous development of the method according to the invention for producing a reusable concrete formwork panel, the coating composition is applied using a roller application system with at least one application roller, which enables particularly simple, rapid, and uniform application. Furthermore, application using more than one roller is also conceivable, for example, using two rollers arranged one after the other. Generally, however, it is preferred that application be carried out exclusively using one or more rollers. In particular, application is carried out using one or more roller coating units. In principle, however, another application method, such as spraying, is also conceivable, either individually or in combination using one or more rollers.

[0032] The application quantity can also be chosen arbitrarily, although an application quantity that is too small will not result in sufficient reusability of the concrete formwork panel, and an application quantity that is too large 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 an amount of between 100 g / m 2 and 300 g / m 2 , preferably between 150 g / m 2 and 250 g / m 2 , particularly preferably between 200 g / m 2 and 240 g / m 2 and most preferably of about 220 g / m 2 occurs.

[0033] A preferred embodiment of the method according to the invention provides that the two-component coating composition is applied directly to at least one of the cover sides and / or without a material layer arranged therebetween and / or impregnated with the coating composition. Direct application of the two-component coating composition means that the two-component coating composition is applied to a fully formed chipboard or coarse particle board and / or directly to the surface of a chipboard or coarse particle board. According to the invention, this application is carried out using a liquid process and preferably exclusively using a liquid process and / or without a solid carrier layer or material layer.Accordingly, it is also preferred that the application be carried out exclusively using liquids and particularly preferably exclusively using the two-component coating composition. Furthermore, when the two-component coating composition is applied directly, the chipboard or coarse particle board has no further coating or is still uncoated, so that the two-component coating composition preferably forms the first and particularly preferably also the only coating of the chipboard or coarse particle board. Application without a material layer is understood to mean that preferably no material layer, regardless of whether impregnated or unimpregnated, is involved in the entire application process of the two-component coating composition.Examples of such undesirable material layers are layers and in particular web material or layers of paper, cardboard, nonwoven fabric, Vukanfiber, a fabric and / or fiber material, of wood, wood chips or wood fibers or any other material.

[0034] In an advantageous embodiment of the method according to the invention, the coating composition is applied to at least both facing surfaces of the chipboard or the coarse particle board, and preferably also to the side surfaces, and in particular, all side surfaces of the chipboard or the coarse particle board. While coating the front facing surface, which comes into direct contact with the concrete, is particularly important, a corresponding coating of the rear facing surface is also preferred, thereby advantageously increasing the number of possible reuses and the service life, since damage and, in particular, swelling from the rear direction are also effectively prevented.Particularly preferred is a coating on all sides and / or the entire surface of the concrete formwork panel, reliably preventing swelling or a bond with the concrete that can only be separated by damaging the concrete formwork panel. Generally, it is preferred that all surfaces of the concrete formwork panel intended for contact with liquid and hardening concrete be provided with a coating.

[0035] Although the concrete formwork panel formed from a particleboard or a coarse particleboard using the described process is already protected against the penetration of water and / or concrete components throughout its surface, particularly in the area of ​​one or both of the cover sides, penetration into the edge area or the side surfaces is still possible, especially if the two-component coating composition has not been applied there or if such a coating has been removed by cutting or milling the side surfaces. This can lead to swelling or material damage in the edge area or on the side surfaces of the concrete formwork panel.In order to prevent this, a preferred embodiment of the method according to the invention provides that in addition to applying the coating composition and in particular applying the coating composition to one or both side surfaces, the side surfaces are subsequently sealed.

[0036] For this sealing, a waterproof coating and / or a hotmelt-based coating is preferably used. Hotmelt adhesives based on ethylene vinyl acetate (EVA), polyamide (PA) and / or polyurethane (PU) can be used as hotmelts, although other hotmelts are also possible. To keep the costs for sealing the side surfaces as low as possible, highly filled hotmelts and / or hotmelts with a short open time are preferably used. A highly filled hotmelt is understood to be a hotmelt adhesive with a filler content of preferably at least 50%, particularly preferably at least 65% and most preferably at least 75% based on the total mass. In addition to the costs, the ambient conditions in which the concrete formwork panels are to be used also play a role, since, for example,Ethylene vinyl acetate-based hot melts typically have a significantly lower melting point than polyurethane-based hot melts, which should be taken into account, for example, when used in regions with high temperatures in summer.

[0037] Additionally or alternatively, a preferred embodiment of the method according to the invention provides that the sealing of the side surfaces takes place by applying a coating and preferably by pressing it into the material of the side surface using a roller. Furthermore, after the sealing of the side surfaces has been applied, any excess sealing material can be removed in the region of the side surface, in particular by cutting it off using a blade and / or on the surface of the cover sides and / or the seal can be smoothed using a second roller. The first roller for application and / or the second roller for smoothing is preferably heated, in particular to a temperature above the melting temperature of the hotmelt. In general, the consumption of hotmelt is significantly higher for a coarse chipboard than for a chipboard due to the more open edge structure.However, a particleboard of the same material thickness has a higher bending strength than a chipboard. Accordingly, a particleboard with a lower thickness can be used than a chipboard. This is particularly relevant with regard to the weight of larger concrete formwork panels, and the use of a particleboard is therefore preferred. For smaller panel sizes and sealed sides, however, a chipboard may be preferred due to the lower material consumption during sealing.

[0038] In general, it's particularly positive that the concrete formwork panels can be recycled after use. A small application quantity of the coating material relative to the panel mass or the mass of the particleboard or coarse particleboard can cause minor problems when reusing the recycled material for the production of wood-based materials, especially after shredding.

[0039] An advantageous development of the method according to the invention for producing a reusable concrete formwork panel provides that the second component of the coating composition, and in particular the release agent component, does not contain a binder used to produce the particle board or chipboard and / or is not a synthetic resin, and in particular not a melamine resin. Rather, in the two-component coating composition, at least one release agent component in the second component is specifically used due to its properties as a release agent, and these properties preferably do not arise as a side effect of a surface coating with a synthetic resin layer.

[0040] Finally, a preferred development of the method according to the invention provides that the two components of the coating composition are each independent and individually usable coating compositions and are mixed with one another in a fixed quantitative ratio, in particular mass or volume ratio, before application. Mixing is particularly preferably carried out immediately before application of the coating composition. Independent and individually usable coating compositions are understood to mean that neither of the two components has a constituent that is absolutely necessary for forming a coating by means of the other component. Accordingly, it is preferably possible for a coating to be formed with each of the two components of the two-component coating composition, although this coating then does not have the properties ordoes not have the suitability according to the invention for multiple use as a concrete formwork panel.

[0041] A preferred embodiment of the concrete formwork panel is one in which the thermosetting carrier resin comprises a melamine resin, and is preferably a melamine resin. However, it is generally 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), methylene diphenyl isocyanate (MDI), also in emulsified form as eMDI, or polyurethane, can also be used individually or in a mixture.

[0042] Furthermore, a concrete formwork panel is preferred in which the release agent component contains a release agent and in particular a hydrophobizing agent, and most preferably is a hydrophobizing agent. Furthermore, the release agent component can also be a complete coating agent 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 reduce wettability.

[0043] Examples of the manufacturing method according to the invention as well as concrete formwork panels and their repeated use are explained in more detail below.

[0044] Example i - Coating of a sanded chipboard

[0045] A sanded OSB in the format 2800 x 2060 x 28 mm was coated in a production line with roller coating units on both sides and on the cover sides with a quantity of approximately 220 g / m 2Coated. 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 and thus forming a release agent component. The coating composition is a mixture of 12 kg of Trollon Activator 2204 Yellow and 6 kg of Trollon Carrier 1400. After mixing the two components of the coating composition, a single coat was applied to a first series of concrete formwork panels, and a double coat was applied to a second series of concrete formwork panels, with intermediate drying by circulating air.

[0046] The coated concrete formwork panels were then pressed 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 / cm 2hardened. 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, especially a separating film, was not necessary.

[0047] Additional tests with a chipboard have shown that, using the same parameters, a concrete formwork panel can also be produced based on a chipboard instead of a coarse chipboard.

[0048] Example 2:

[0049] A sanded OSB sheet with the coating described in Example 1, measuring 2650 x 2070 x 28 mm, was first cut into 2502 x 627 x 28 mm blanks on a cutting saw. The resulting blanks for concrete formwork panels were then milled lengthwise in a continuous feed to a size of 625 mm on a double-end tenoner operating at a feed rate of 20 m / min.

[0050] The two long edges of the concrete formwork panels are then coated with an adhesive, specifically a highly filled EVA hot melt with a short open time, using a roller application. This adhesive was chosen because the open areas of the OSB in the edge needed to be filled as cost-effectively as possible. The hot melt was first pressed into the edge with a roller and then smoothed with a smooth roller. Any hot melt on the top and / or bottom sides was removed with a spring-loaded scraper. The concrete formwork panels with coated long edges are then rotated so that the edges on the short side can be processed in the same way. The concrete formwork panel is first milled to a size of 2500 mm and then the edges are coated with a highly filled EVA hot melt with a short open time, as already described for the long edges.

[0051] Example 3 - Coating of an unsanded chipboard

[0052] An unsanded OSB in the format 2800 x 2060 x 28 mm was coated in a production line with roller coating units on both sides and on the cover sides with a quantity of approximately 220 g / m 2 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, thus forming a release agent component. The coating composition is a mixture of 12 kg of Trollon Activator 2204 Yellow and 6 kg of Trollon Carrier 1400.

[0053] After mixing the two components of the coating composition, a single coat was applied to a first series of concrete formwork panels, and a double coat was applied to a second series of concrete formwork panels, with intermediate drying by circulating air. Despite the release agent still present on the surface, surprisingly, the coating result was similarly good as in Example 1.

[0054] The coated concrete formwork panels were then pressed 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 / cm 2hardened. The concrete formwork panels detached easily from the press plates and could be transported by the infeed / outfeed carriage from the short-cycle press. Furthermore, the use of a separating layer, particularly a separating film, was not necessary. Here, too, a similar result was observed as in Example 1. Additional tests with a particle board have shown that, using the same parameters, a concrete formwork panel based on a particle board can also be produced instead of a coarse particle board.

[0055] Example 4 - minimal coating of a chipboard

[0056] A sanded OSB in the format 2800 x 2060 x 28 mm was coated in a production line with roller coating units on both sides and on the cover sides with a quantity of approximately 150 g / m 2coated. The coating composition corresponded to the composition in the first exemplary embodiment. A single application was carried out at a high application speed to allow for the formation of individual defects in the coating.

[0057] The coated concrete formwork panels were then pressed 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 / cm 2 cured.

[0058] Example 5 - Concrete formwork test

[0059] From the coated concrete formwork panels produced in examples 1, 2 and 3, blanks were produced, from which concrete formworks were then produced in a size of 300 x 200 x 200 mm (L x W x D).

[0060] Each of these molds was filled with a commercially available screed concrete, the screed was allowed to harden, and then the screed element was removed. The demolding was tested for its effectiveness, the degree of concrete coverage on the surface, and how easily the residue could be brushed off. This procedure was repeated a total of seven times for each mold.

[0061] For all concrete formwork panels tested, only a minor deterioration in demolding and brushing effort was observed. As in the other areas, no significant swelling or coating delamination was evident in the defects from Example 3. No wave-like defects or other deterioration in surface quality were evident on the concrete element either.

Claims

Claims 1. Method for producing a reusable concrete formwork panel, in particular for exposed concrete, comprising the steps: Providing a chipboard or a coarse chipboard having two cover sides and side surfaces, Applying a two-component water-based coating composition by liquid process to at least one of the cover sides, wherein one component of the coating composition comprises a thermosetting carrier resin and the second component comprises at least one release agent component, Curing the applied coating composition in a hot press to form a closed coating on the chipboard or the coarse particle board.

2. A method for producing a reusable concrete formwork panel according to claim i, characterized in that the curing of the applied coating composition takes place in a short-cycle press.

3. A method for producing a reusable concrete formwork panel according to claim 1 or 2, characterized in that the curing of the applied coating composition takes place over a period, in particular a pressing time, of between 15 s and 60 s.

4. A method for producing a reusable concrete formwork panel according to at least one of the preceding claims, characterized in that the curing of the applied coating composition takes place at a temperature, in particular a pressing temperature, between 175 °C and 225 °C. 5- Method for producing a reusable concrete formwork panel according to at least one of the preceding claims, characterized in that the curing of the applied coating composition takes place at a pressure, in particular a pressing pressure, between 40 kg / cm 2 and 60 kg / cm 2 takes place.

6. A method for producing a reusable concrete formwork panel according to at least one of the preceding claims, characterized in that the coating composition is applied by means of a roller application system having at least one application roller.

7. A method for producing a reusable concrete formwork panel according to at least one of the preceding claims, characterized in that the coating composition is applied in an amount of between 150 g / m 2 and 250 g / m 2 takes place.

8. A method for producing a reusable concrete formwork panel according to at least one of the preceding claims, characterized in that the two-component coating composition is applied directly to at least one of the cover sides and / or without a material layer arranged therebetween and / or impregnated with the coating composition.

9. A method for producing a reusable concrete formwork panel according to at least one of the preceding claims, characterized in that the coating composition is applied at least to both cover sides of the chipboard or the coarse chipboard and / or to the side surfaces.

10. A method for producing a reusable concrete formwork panel according to at least one of the preceding claims, characterized in that in addition to applying the coating composition to one or both side surfaces, sealing of the side surfaces is carried out, for which purpose a waterproof coating and / or a hotmelt-based coating is preferably used for sealing and / or the sealing of the side surfaces is preferably carried out by applying a coating using a roller.

11. A method for producing a reusable concrete formwork panel according to at least one of the preceding claims, characterized in that the second component of the coating composition and in particular the release agent component does not contain a binder used to produce the chipboard or coarse chipboard and / or is not a melamine resin.

12. A method for producing a reusable concrete formwork panel 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 application.

13. Concrete formwork panel for multiple use in concrete casting, in particular for exposed concrete, with a base body made of a chipboard or a coarse chipboard which has two cover sides and side surfaces, a coating of at least one of the cover sides made of a two-component water-based coating composition, wherein one component of the coating composition has a thermosetting carrier resin and the second component comprises at least one release agent component, and wherein the coating is formed by pressing on the coating composition by means of a hot press for curing and / or the coating is pressed into a surface of the base body. 14- Concrete formwork panel according to claim 13, characterized in that the thermosetting carrier resin is a melamine resin.

15. Concrete formwork panel according to claim 13 or 14, characterized in that the release agent component hydrophobizes the coating formed from the coating composition and / or the second component contains a hydrophobizing agent as a release agent component.