Method for producing a concrete formwork board, and concrete formwork panel for multiple use

Abstract

The invention relates to a method for producing a reusable concrete formwork panel and a concrete formwork panel for multiple use in concrete casting. In order to provide a method for producing a concrete formwork panel and a concrete formwork panel that enable multiple use and particularly cost-effective production, wherein the concrete formwork panels are also suitable for casting exposed concrete, it is provided that a chipboard or a coarse chipboard having two cover sides and side surfaces is first provided, followed by the application of a two-component, water-based coating composition by a liquid process to at least one of the cover sides, wherein one component of the coating composition has a thermosetting carrier resin and the second component comprises 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 on the coarse particle board.

Description

[0001] 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.

[0002] Formwork is required as an aid for a variety of concrete projects on construction sites. State-of-the-art formwork includes both very high-quality and correspondingly expensive formwork, as well as lower-quality and correspondingly inexpensive formwork.

[0003] High-quality formwork is typically a modular formwork system used with an assembly / fastening system and is usually made of laminated plywood or laminated solid wood panels. These high-quality formwork panels are designed to be used for as long as possible and for multiple uses. 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.

[0004] 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 not only precludes reuse but also creates an uneven, wavy structure on the concrete surface, making these formwork panels unsuitable for use in exposed concrete.

[0005] 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.

[0006] 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 10. Advantageous further developments are specified in the dependent claims.

[0007] 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 intermediate side surfaces 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 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 elevated pressure and / or elevated temperature to form a continuous coating on the chipboard or the coarse particle board.

[0008] 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 / or elevated temperature and / or the coating is pressed into a surface of the base body.

[0009] It has surprisingly been found that coating chipboard and coarse particle board using a hot press and using 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 accordingly, the concrete formwork panel 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.

[0010] A concrete formwork panel is essentially a single panel of formwork 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 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.

[0011] According to the invention, the concrete formwork panel is reusable, which means 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.

[0012] The concrete formwork panel can be simply a plate-shaped workpiece for arbitrary attachment as part of a concrete formwork or, as part of a formwork system, can have permanently attached fastening elements. However, the concrete formwork panel according to the invention is preferably 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 customized to individual dimensions, for example, by cutting.

[0013] 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 an upper side and the other cover side is an underside of the chipboard or the coarse particle board. The concrete formwork panel or the chipboard or the coarse particle board is preferably rectangular and accordingly has four side surfaces.

[0014] The chipboard or the coarse particle board can, in principle, have either an unchanged surface after production of the board or a machined surface. However, it is preferred that the surface of the chipboard, and in particular of a coarse particle board, is sanded before application of 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 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.Furthermore, it is preferred that each concrete formwork panel is formed from exactly one single chipboard or coarse chipboard.

[0015] 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 mean a composition with water as the essential solvent and / or a hydrophilic and / or water-soluble composition.

[0016] According to the invention, the coating composition is applied using a liquid process to at least one of the outer surfaces. 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 outer surfaces, over the entire surface and / or covering it, so that a closed, complete, and / or surface-smooth coating is also preferably obtained after curing.

[0017] 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.

[0018] 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 storage-stable 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 that one of the components is solid and in particular in powder form. In general, however, it is preferred that at least one of the two components is liquid.It is further 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.

[0019] 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 essentially from the carrier resin or can contain any number of additional 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 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.

[0020] According to the invention, the second component comprises or is a release agent component at least one 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.

[0021] 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 about 1:2.

[0022] 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.

[0023] 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 / or elevated 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 was cured under pressure or during a pressing process and that the coating composition was thereby 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 obtained, despite any surface defects and unevenness that may be present.In addition, it is also conceivable that 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.

[0024] 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. However, by using a structured press plate, 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.

[0025] 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, thereby enabling particularly rapid 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, thereby simplifying the pressing process and simultaneously making it more economical.

[0026] The applied coating composition can, in principle, be cured for any desired duration, at any desired pressure, and at any desired temperature. In a preferred embodiment, the applied coating composition is cured for a duration, in particular a pressing time, of between 10 s and 120 s, preferably between 15 s and 60 s, more preferably between 20 s and 40 s, and most preferably about 30 s. Additionally or alternatively, the applied coating composition is cured at a temperature, in particular a pressing temperature, of between 150°C and 250°C, preferably between 175°C and 225°C, more preferably between 190°C and 210°C, and most 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 very particularly preferably at about 50 kg / cm 2< (4.9 MPa).

[0027] 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 by one or more rollers. In particular, application is carried out by 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.

[0028] The application quantity can also initially 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 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 .

[0029] In an advantageous embodiment of the method according to the invention, the coating composition is applied at least to both cover surfaces of the chipboard or the coarse particle board and preferably also to the side surfaces of the chipboard or the coarse particle board. Particularly preferred is an all-round and / or complete coating of the surface of the concrete formwork panel, so that swelling or a bond with the concrete that can only be released with damage to the concrete formwork panel is reliably prevented. It is generally preferred that all surfaces of the concrete formwork panel intended for contact with liquid and hardening concrete be provided with a coating.

[0030] 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 chipboard or particleboard leads to minor problems when reusing the recycled material for the production of wood-based materials, especially after shredding.

[0031] 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.

[0032] 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, may also be used individually or in a mixture.

[0033] 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 the wettability.

[0034] Embodiments of the manufacturing method 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 chipboard

[0035] A sanded OSB (oriented strand board) measuring 2800 × 2060 × 28 mm was coated on both sides and the entire surface of the outer surfaces with a coating weight of approximately 220 g / m² in a production line with roller coating units. The coating composition consists of two water-based components that are mixed immediately before application. Each of the components 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.

[0036] 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 circulating air.

[0037] The coated concrete formwork panels were then cured in a short-cycle press for 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 by the infeed / outfeed trolley from the short-cycle press. Furthermore, the use of a separating layer, especially a separating film, was not required.

[0038] Additional tests with a chipboard have shown that with the same parameters, a concrete formwork panel can also be produced based on a chipboard instead of a coarse chipboard. Example 2 - Coating of an unsanded chipboard

[0039] An unsanded OSB (oriented strand board) measuring 2800 × 2060 × 28 mm was coated on both sides and the entire surface of the outer surfaces with a coating weight of approximately 220 g / m² in a production line with roller coating units. The coating composition consists of two water-based components that are mixed immediately before application. Each of the components 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.

[0040] 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 remaining on the surface, the coating result was surprisingly similar to that of Example 1.

[0041] The coated concrete formwork panels were then cured in a short-cycle press for 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 trolley. 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.

[0042] Additional tests with a chipboard have shown that with the same parameters, a concrete formwork panel can also be produced based on a chipboard instead of a coarse chipboard. Example 3 - minimal coating of a chipboard

[0043] A sanded OSB (oriented strand board) measuring 2800 × 2060 × 28 mm was coated on both sides and on the outer surfaces with a coating quantity of approximately 150 g / m² in a production line with roller coating units. The coating composition corresponded to the composition in the first example. A single application was carried out at a high application speed to allow for the formation of individual defects in the coating.

[0044] The coated concrete formwork panels were then 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 / cm 2 . Example 4 - Concrete formwork test

[0045] From the coated concrete formwork panels produced in examples 1, 2 and 3, blanks were produced, from which concrete formworks were then produced, each measuring 300 × 200 × 200 mm (L × W × D).

[0046] 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 the ease with which the residue could be brushed off. This procedure was repeated a total of seven times for each mold.

[0047] For all concrete formwork panels examined, only a minor deterioration in demolding and brushing effort was observed. As in the other areas, no significant swelling or coating detachment was evident in the defects from Example 2. No wavy defects or other deterioration in surface quality were evident on the concrete element either.

Claims

1. A method for producing a reusable concrete formwork panel, in particular for exposed concrete, comprising the steps of: - providing a chipboard or a coarse chipboard which has two cover sides and side surfaces, - applying a two-component, water-based coating composition by a liquid process to at least one of the cover sides, - wherein one component of the coating composition has 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 chipboard.

2. A method for producing a reusable concrete formwork panel according to claim 1, 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. A method for producing a reusable concrete formwork panel according to at least one of the preceding claims, characterized in that curing the applied coating composition 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 applying the coating composition in an amount 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 coating composition is applied to at least both facing sides of the chipboard or the coarse particle board.

9. A method for producing a reusable concrete formwork panel according to at least one of the preceding claims, characterized in thatthe two components of the coating composition are each independent and individually usable coating compositions and are mixed together in a fixed ratio before application.

10. 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.

11. Concrete formwork panel according to claim 10, characterized in that the thermosetting carrier resin is a melamine resin.

12. Concrete formwork panel according to claim 10 or 11, 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.