Procedure for manufacturing an extruded plate

Abstract

A method for producing an extruded sheet comprising the following steps: - providing calcium carbonate (CaCO3) powder and polyvinyl chloride (PVC) powder, - providing additives, wherein the proportion of calcium carbonate (CaCO3) powder is between 60 and 80% by weight, the proportion of polyvinyl chloride (PVC) powder is between 20 and 40% by weight, and the proportion of additives is up to 5% by weight; - mixing the calcium carbonate (CaCO3) powder with the polyvinyl chloride (PVC) powder and the additives, and heating the mixture to obtain a kneadable mass, - melting and extruding the mass by means of an extruder and shaping it into a sheet by means of a groove die, - pressing the still-hot sheet to obtain a desired final thickness.

Description

Procedure for the production of an extruded plate The invention relates to a process for the production of an extruded plate with the following steps: a) disposition of calcium carbonate (CaCO3) powder, b) disposal of polyvinyl chloride (PVC) powder, c) provision of additives as stabilizers, consisting of at least Ca / Zn stabilizers, impact-tough components and internal and external waxes, where c) the proportion of calcium carbonate powder (CaCO3) between 60 and 80% by weight, the proportion of polyvinyl chloride (PVC) powder between 20 and 40% by weight and the proportion of additives up to 5% by weight, d) mixing calcium carbonate powder (CaCO3) with the polyvinyl chloride (PVC) and the additives, e) heating the mixture to a temperature of 100 to 140°C until the polyvinyl chloride (PVC) softens to give a kneadable mass and the calcium carbonate (CaCO3) bonds at least partially with the polyvinyl (PVC), f) cooling the mass to a temperature of 40 to 50 °C, g) transport of the mass to an extruder, h) melting and extrusion of the mass by means of an extruder and molding by means of a slotted nozzle to give a plate, i) compressing the still-hot plate using at least two calendering rollers to a desired thickness. The invention further relates to a plate produced according to this process. This plate is preferably used as floor covering. For example, a similar plate is known from document WO 2014 / 161956 A1. US2017190848A1 describes a process for the production of polymer composites that allows the production of composites with a high filler content. Currently, polyvinyl chloride (PVC) flooring is in vogue, often marketed as vinyl flooring or LVT (Luxury Vinyl Tiles). Vinyl is a popular flooring choice for homes because it offers good hygienic properties, is extremely functional, and can also be made to feel pleasant to the touch. These floor coverings are manufactured in thicknesses of approximately 5 mm and can be glued down. PVC panels suitable for floating installation without glue, using click profiles similar to laminate flooring, are also available. Compared to laminate flooring, PVC flooring has the advantage of being moisture-resistant, having a more pleasant feel, and providing sound insulation against impacts and footsteps. It can also be made with deep surface textures.It is a disadvantage that vinyl flooring, or LVT, has limited dimensional stability and expands with heat, but only returns to its original shape with cold under certain conditions. Cracking can even occur within a room if the floor is only partially heated, for example, in the area of ​​a window facing the sun. Because these products are softer than laminate, irregularities may be noticeable on the upper surface of the subfloor. To some extent, these irregularities are visible, which is undesirable. The use of plasticizers is not considered harmful to health by a significant portion of the population, although their use is regulated by strict legal provisions. A PVC floor covering for temporary floor coverings is known from patent DE 82 17074 U1. The covering is rectangular in shape and has a heavy-duty backing layer bonded to it. This backing layer is a plastic sheet with a textured surface profile. The backing layer contains a high proportion of filler material and is so soft that it does not adhere to the floor even under impact loads. A floor covering with a polyvinyl chloride (PVC) core, containing additional filler materials, is known from document DE 202012004994 U1. A PVC wear layer is bonded to the top of the core. The panels are fitted with joining and locking mechanisms along their opposite edges, allowing them to be joined and secured together. Production of such a panel is quite expensive. Calcium carbonate (CaCO3) is commonly used as a filler material in the PVC industry. US patent 2017 / 0446845 A1 discloses a plastic sheet produced from PVC powder and a mixed powder of light calcium with other additives, bonded between three calendering rolls with a wear-resistant layer and a paper layer. The sheet can be applied with a surface layer in a multi-roll calender, and the top layer can be made of plastic. Based on this, the invention aims to create a floor covering that possesses the positive properties of PVC flooring but avoids its aforementioned drawbacks, particularly the "telegraphing" of irregularities in the subfloor. Furthermore, it aims to present a particularly high-quality visible surface that provides a pleasing visual impression to the observer. For this problem-solving procedure, at least one coat of pigmented lacquer is applied to the top surface, followed by another coat of lacquer to increase scratch resistance. The additional varnish is preferably applied in at least two coats. To ensure good abrasion resistance, the first coat is applied in an amount of approximately 80 to 100 g; to achieve scratch resistance, the second coat is applied in an amount of approximately 10 to 30 g. The process according to the invention reverses the approach commonly used to date for the production of PVC boards. A mineral substrate is created, and calcium carbonate is used as the base for the board, which is then bonded with PVC. The board produced according to this process is highly dimensionally stable, water-resistant, and has a high specific weight. This ensures a pleasant sound underfoot and is sufficiently hard to compensate for subfloor irregularities, thus preventing "telegraphing." Furthermore, it is stable enough to allow for edge profiling and the installation of so-called "click profiles," which enable the joining of several boards without glue. Click profiling is well known in the laminate flooring industry (for example, see document DE 198 51 200 C2 or document WO 97 / 047834 A1).Thanks to the greater elasticity of the material and the homogeneous surface compared to wood panels, a wider variety of click profiles can be used. It has been shown that particularly good results are obtained when the proportion of CaCO3 is higher than the proportion of PVC. The proportion of calcium carbonate powder (CaCO3) is preferably between 65 and 80% by weight, especially between 70 and 80% by weight, and most preferably 75% by weight. The proportion of polyvinyl chloride powder (PVC) is adjusted accordingly and is preferably between 20 and 35% by weight, especially between 20 and 30% by weight, and most preferably 25% by weight. In this case, the proportion of additives must naturally be taken into account. First, preferably only 30% to 40% of the prepared proportions of calcium carbonate (CaCO3) powder by weight are mixed (while hot) with the polyvinyl chloride (PVC) powder and additives. The remaining proportions of calcium carbonate (CaCO3) powder by weight are then mixed into the mass to be cooled or already cooled. Coloring pigments, such as soot, can also be added at the beginning or during the mixing of the remaining prepared calcium carbonate (CaCO3) powder to produce a colored plate. The polyvinyl chloride powder and additive powder is preferably free of plasticizers, so that a plate completely free of plasticizers can be produced. Calcium zinc (Ca / Zn) as a stabilizer is preferably used in an amount of less than 5 parts by weight. The grain size of the polyvinyl chloride powder is in the range of 80 to 200 µm. Calcium carbonate powder is preferably used in a grain size of 1 to 10 µm. The slotted nozzle of the extruder preferably has a width of 1,250 mm and / or a thickness of 2 to 10 mm, especially preferably 4 mm, so that a large-format plate can be produced from which a large number of individual panels can be cut. The plate width can correspond to the length of a panel. The extruded plate is preferably fed through three or four, especially up to five, calendering rolls, and a texture can also be applied to the surface of the extruded plate using the calendering rolls. The texture can also be applied using a pressed sheet or a textured sheet. In a first step, the structure of the upper side can preferably be marked, and in a second step, the decoration can be printed using digital printing, taking into consideration the structure. If the top side of the board is textured, it can be brushed after the first coat of varnish has been applied to ensure that the texture is not covered by the varnish layer. For this purpose, at least one rotating brush is provided, covering the entire width of the board. In this case, the brush's axis of rotation can be positioned at a right angle to the board's direction of transport. An oblique position of the axis of rotation relative to the board's direction of transport is also possible. Several brushes can also be arranged in series. Naturally, brushing does not completely remove the varnish from the top side; it merely recreates the texture. Ideally, both additional varnishes should have different gloss levels to enhance the structure's visual appearance. The first varnish layer, which can be brushed onto the structure, determines the gloss level on the surface and may preferably be softer than the second, or final, varnish layer applied. This second layer increases scratch resistance and should be applied to the raised portions of the structure, determining their gloss. Scratch resistance is less critical in recesses than on raised areas. The second coat of varnish is preferably applied using a cellular rubber roller, after the first coat has been brushed into the crevices with a rotary brush. The first coat of varnish can be hardened before applying the second coat. Preferably, both varnishes have different strengths; in particular, the first varnish may be softer than the second. To prevent the varnishes from penetrating the voids of the structured surface of the board and destroying, or at least significantly diluting, the structural effect, a casting varnish may be applied at high flow rates, for example, 120 m / s, and then immediately hardened with electron beam radiation or very strong UV lamps, or a combination of both, to such an extent that flow into the voids of the structure is no longer possible. If, together with the plate, a polyvinyl decoration film and / or a polyvinyl chloride protective film is fed through the calendering rollers and pressed with the plate, production is further simplified and a ready-to-use product is generated that only needs to be divided into individual panels. A decorative sheet can also be bonded to the top side of the extruded sheet. This can be done on the textured top side. Further texturizing of the bonded decorative sheet is also possible. The top side can be printed with a decoration. The printing can be done digitally. For this purpose, it is preferable to prime the top side before printing. The primer can be tinted. Instead of, or in addition to, the primer, a pigmented primer can also be applied. The pigmented primer creates a base for the printed decoration, thus saving paint later. The decor is preferably a wooden decoration. The top surface of the plate is coated with pigmented lacquers, for example, to obtain a solid-colored plate. This lacquer finish is preferably high gloss. The decorative printing is preferably done in accordance with the pattern marked on the upper side of the plaque. The printing can be done in a synchronized manner. For example, in the case of a wood decoration, the printing and the pattern reproduce the wood grain and pores, creating the impression of natural wood not only visually, but also to the touch. A single-color varnish can also be applied over a structured top side. The extruded board can also be bonded to a wood veneer. The wood veneer can be varnished with highly abrasion-resistant varnishes or given a corresponding coating and mounted with a finishing varnish in combination with a primer. This completely and naturally reproduces the character of wood. With this option, an extremely thin, dimensionally stable wood floor is achievable, with a moisture-resistant and high-load-bearing subfloor that can even be used in damp environments. To increase scratch resistance, the coated plate is varnished. This varnishing can be done with UV-cured or electron-cured varnishes, or with a hot-applied polyurethane or polyolefin coating. On the underside, that is, the side opposite the facing, the board can be coated, in particular, with XPS (extruded polystyrene) or cork for impact noise insulation. This improves the soundproofing properties of footsteps, as these are reduced due to the board's high specific weight, which is preferably between 1,900 and 2,100 kg / m³, especially 2,000 kg / m³. For impact noise insulation, in principle, all commercially available products are suitable. The facing, especially the extruded polystyrene or cork layer, is preferably applied at a thickness of 1.0 to 1.5 mm. The panel is dimensionally stable and can be used not only as flooring, but also for walls or ceilings. Its dimensional stability allows it to be used as a floating floor covering or glued to the subfloor. From the large-format slab, panels (boards) or smaller slabs can be cut. These slabs can be used as tiles to clad a wall or subfloor, for example. For reasons of cost and weight, when used as wall cladding, a thickness of 2 to 3 mm is preferred. The tile can be smooth or textured. Production involves mixing calcium carbonate powder (CaCO₃) and PVC powder in a mixer. The powder is then mixed with additives and heated to approximately 120°C. Initially, only about 30% of the calcium carbonate powder is mixed with the polyvinyl chloride powder, allowing the calcium carbonate to bond to the surface or within the PVC. If the powder is sufficiently mixed and the mixture is kneadable, it is cooled to 40–50°C, and the remaining 70% of the calcium carbonate powder is then mixed into the cooled or chilled mass. This method saves energy because the entire calcium carbonate powder does not need to be heated immediately. Since only about 20–30% of the CaCO₃ powder bonds to the surface or within the PVC anyway, mixing the remaining CaCO₃ powder into the cooled mass is not problematic.However, in principle, all the parts can be mixed immediately by weight. In this case, the free calcium carbonate powder distributes very well throughout the mixture. In one example of a preferred embodiment, 300 parts by weight of calcium carbonate powder, 100 parts by weight of polyvinyl chloride powder, and 15 parts by weight of additives such as stabilizers are used. To prevent separation, this mass is conveyed to an extruder, preferably by means of screws. To ensure good bonding of the individual components, the extruder is equipped with screws that form a long holding zone. At the extruder outlet is a slotted nozzle, the width and thickness of which are selected according to the desired sheet dimensions. A width of 1,250 mm and a thickness of 4 mm have proven to be conveniently manageable. Sheet material emerges from the slotted nozzle at a temperature of approximately 165°C and is pressed to its final thickness by three vertically arranged calibrating rollers. During calibration, the material is fed through the vertical roller arrangement twice in a semicircle, first through the second roller and then through the third.What's special about the process is that a printed PVC decorative film and a protective PVC film can be fed through the calender simultaneously with the board. The second calender is also equipped with a textured surface (usually a wooden structure), so that the finished board at the end has a textured decorative surface and a protective layer, which must then be varnished to increase scratch resistance. Afterward, the edges are shaped and profiled. The PVC decorative films and / or protective films used may contain plasticizers. This board variant is not completely plasticizer-free, but contains significantly less plasticizer than conventional LVT. The process can also be carried out in a variation where the material, or the slab, is calibrated without the application of a decorative film. A smooth calender, rather than a textured one, is then used. The slab is then digitally printed or printed with pigmented varnishes, subsequently cut into panels, and, if necessary, given appropriate protective and finishing varnishes. Finally, it is finished to create a floor. UV varnishes, or preferably varnishes that cure by electron beam, can be used in this process. The latter have proven particularly suitable for flooring. In this variation, the final product contains absolutely no plasticizers. In another variation, the material, or the slab, can be given a textured surface during calibration, but without a decorative or protective film.The top side of the plaque is first primed with a pressure primer, then digitally printed, precisely so that the printed image matches the structure (embossed register). This can depict wooden decorations, stone decorations, and all other motifs (fantasy decorations). Finally, a protective varnish is applied using pouring varnishes that conform to the plaque's surface. The finishing varnishes are applied using cellular rubber rollers. UV varnishes or electron beam curing varnishes can also be used. This variant is also free of plasticizers. What is special about this variant is that the (digital) decorative printing is carried out after the top surface of the plate has been textured. Consequently, the printed image conforms to the texture. The texture is conventionally marked on the top surface of the plate at the end, meaning the texture is adapted to the decoration. The plate can be produced in any desired color. The board arriving at the extruder can also be supplied unstructured. In this case, it can be coated with a pigmented varnish to create, for example, a single-color board. Coating the pigmented board can also be done on a structured surface. To increase resistance to chipping and abrasion, the coated or varnished board is then coated with UV-cured or electron-cured varnishes, or with a hot-applied polyurethane or polyolefin coating. Impact noise insulation can be applied to all the aforementioned variants if the panel is to be used in the floor area. Footstep noise, i.e., the perceived noise in the space, is highly beneficial due to the panel's high specific weight.

Claims

Yo. A process for producing an extruded plate comprising the following steps: a) preparation of calcium carbonate (CaCO3) powder, b) preparation of polyvinyl chloride (PVC) powder, c) preparation of additives such as stabilizers, consisting of at least Ca / Zn stabilizers, impact-resistant components, and internal and external waxes, wherein c1) the proportion of calcium carbonate (CaCO3) powder is between 60 and 80% by weight, the proportion of polyvinyl chloride (PVC) powder is between 20 and 40% by weight, and the proportion of additives is up to 5% by weight, d) mixing of calcium carbonate (CaCO3) powder with polyvinyl chloride (PVC) and the additives, e) heating the mixture to a temperature of 100 to 140°C until the polyvinyl chloride (PVC) softens to form a mass kneadable and calcium carbonate (CaCO3) bonds at least partially with polyvinyl (PVC), f) cooling the mass to a temperature of 40 to 50 °C,g) transporting the mass to an extruder, h) melting and extruding the mass by means of an extruder and molding by means of a slotted nozzle to form a plate, i) compressing the hot plate to the desired final thickness using at least two calendering rollers.

2. A process according to any of the preceding claims, characterized in that the extruder die has a width of 1,250 mm and / or a thickness of 2 to 10 mm, preferably 4 mm.

3. A process according to any of the preceding claims, characterized in that the extruded plate is guided over three calendering rollers.

4. A process according to any of the preceding claims, characterized in that the extruded plate is guided through at least two calendering rollers.

5. A process according to any of the preceding claims,characterized in that a structure is stamped onto the upper surface of the extruded plate by means of calendering rollers.

6. A method according to any one of claims 1 to 3 or 5, characterized in that a decorative film is laminated onto the upper surface of the plate.

7. A method according to claim 5, characterized in that the upper surface is printed with a decoration that coincides with the structure, in particular one that is synchronized with it.

8. A method according to claim 7, characterized in that the decorative printing is carried out digitally.

9. A method according to claims 7 or 8, characterized in that the upper surface is primed before printing or lacquering.

10. A method according to any one of claims 7 to 9, characterized in that the decoration is a wood decoration, a stone decoration, or a fantasy decoration.

11. A method according to any one of the preceding claims,characterized in that the upper surface of the plate is varnished to increase scratch resistance.

12. A method according to claim 11, characterized in that the varnish is applied to the polyvinyl chloride (PVC) film or films, or to the decorative film, the decorative print, or the pigmented varnish.

13. A method according to any of the preceding claims, characterized in that the extruded plate is divided into a plurality of smaller plates, in particular panels.