Method for producing a laminate comprising at least one kraft paper layer and at least one other paper layer

Abstract

The present invention relates to a method for producing a laminate comprising at least one kraft paper layer, the method involving the following steps: providing at least one raw kraft paper layer, applying at least one first layer of at least one powdered resin on at least one side of the kraft paper layer, placing at least one other paper layer on the side of the kraft paper layer sprinkled with powdered resin, and compressing the layer structure.

Description

[0001] Process for producing a laminate comprising at least one kraft paper layer and at least one further paper layer

[0002] The present invention relates to a method for producing a laminate comprising at least one kraft paper layer and at least one further paper layer and laminates producible by this method.

[0003] Description

[0004] Laminates are layered materials made of pressed paper impregnates that are applied (laminated) to carrier boards. Currently known in the state of the art are, for example, laminates in which the composite layer comprises at least one impregnated paper layer, such as a decorative impregnate, at least one transparent paper layer (glassine), e.g., glassine treated with sulfuric acid, and / or at least one plastic film layer.

[0005] A distinction is made between high-pressure laminate (HPL) and continuous pressure laminate (CPL). HPL is a laminate produced in sheet form using a high-pressure pressing process, consisting of several layers of paper and resin, which is manufactured in a multi-daylight press. CPL is produced continuously from several layers of paper and resin. It is usually available in rolls and is used, for example, for the production of worktops, wrapped profiles, and door panels. CPL is pressed in a continuous or continuous process in roller belt presses heated on both sides. In both HPL and CPL, kraft paper is used as at least one paper layer. Kraft paper is highly durable, with a weight of up to 200 g / m 2 and consist of cellulose fibers to which starch, alum and glue are added to achieve surface effects and increase strength.

[0006] When producing CPL on double-belt presses, resin-impregnated kraft paper layers in the form of soda kraft paper (SPP) are used in the core layer, just as with HPL. While HPL typically uses SPPs impregnated with phenolic resin, CPL typically uses SPPs with a blend of melamine and phenolic resin. The resin application for HPL kraft paper in the core layers is typically 40-50 wt%. For CPL core layers, it is 80-90 wt%.

[0007] The kraft papers are impregnated in impregnation channels, some of which operate at speeds > 100 m / min. While impregnates for HPL are produced from kraft paper sheets, those for CPL are produced from kraft paper rolls. This also applies to the remaining impregnates used in a CPL line (decorative, overlay, or balance impregnates). Sheets are used only in exceptional cases.

[0008] Since the rolls can be several hundred meters long, depending on the paper weight, they represent a significant commodity. During roll production, however, quality control (final weight, resin application, moisture content) can only be performed at the end of the roll. This, however, provides no information about the resin application and moisture content within the roll. Fluctuations in the process (temperature of the impregnating resins and NKP, temperature in the production hall, temperature fluctuations in the drying tunnel, etc.) or in the raw material (grammage, paper moisture content, etc.) can result in impregnated rolls that cause problems in the CPL system. These can include delamination, warping, etc. However, the process could be monitored by installing online analytics (near-infrared spectroscopy, microwave, etc.).However, the problem remains that due to the high production speeds, large quantities of impregnated material of poor quality are still produced, as there are still minutes of production time between detection and correction.

[0009] In addition, many CPL manufacturers do not produce the impregnated kraft paper layers used in core layers themselves, as a high-speed impregnation channel usually has significantly more impregnation capacity than can be processed on one or two CPL systems. Due to contamination reasons, decorative papers or overlays cannot be impregnated with melamine resins on an impregnation channel used to process phenolic resins. This is not possible even after extensive channel cleaning. CPL manufacturers are therefore dependent on the impregnation qualities of the kraft paper layers available on the market. If these lead to problems on their system, they can only rectify the deficiencies by changing the system parameters (temperature, system speed and pressure). A particularly negative factor is that impregnates are usually delivered in full trucks.This means that the producer has a large number of rolls in stock, which can only be tested for their suitability in production by trial and error.

[0010] Furthermore, it is often difficult to achieve specific product properties by adding additives to the impregnation baths. Sometimes the additives are poorly soluble in water, and sometimes their addition leads to segregation in the impregnation tank. This complicates the impregnation process and makes achieving the desired properties difficult or even impossible.

[0011] Furthermore, the entire width of the fabric is always impregnated during impregnation. This can later lead to contamination of the press belts / texturing agents due to resin leaking from the edges on the CPL line under pressure and temperature. Attempts are being made to solve this problem by applying solvent to the edges before entering the impregnation tank. However, the amount and nozzle positioning must be monitored. Furthermore, the time between application and immersion into the impregnation tank is relatively short due to the high speed, so proper impregnation of the edge area is not achieved.

[0012] This results in several disadvantages. For example, determining the quality in the roll is difficult, as is changing the property profile. Impregnating the edge area is also problematic, and water-insoluble additives cannot be used in the impregnation process.

[0013] The invention is therefore based on the technical problem of remedying the deficiencies described above. In particular, it is desirable to provide an approach for carrying out the impregnation of kraft paper layers directly on-site at the CPL manufacturer, thus avoiding the need to rely on the delivery of pre-impregnated kraft paper layers with the disadvantages described above. The low demand of a single CPL plant should also be taken into account. The adaptation of the impregnated kraft paper layers with regard to resin application, moisture content, or other parameters should also be possible quickly and precisely. Furthermore, the addition of auxiliary materials to achieve resin / product properties should also be easy. In addition, powdered / fibrous fillers (cellulose, flours, inorganic and organic fibers, etc.) should also be usable.Adaptation to different web widths should also be possible quickly and avoid material losses.

[0014] This object is achieved by a method having the features of claim 1.

[0015] Accordingly, a method for producing a laminate, in particular a CPL, comprising at least one kraft paper layer is provided, the method comprising the following steps: providing at least one non-impregnated or raw kraft paper layer,

[0016] - applying at least one first layer of at least one powdered resin to at least one side of the kraft paper layer,

[0017] - placing at least one further paper layer on the side of the kraft paper layer sprinkled with the powdered resin, and

[0018] - Pressing the layer structure.

[0019] Accordingly, a multi-step process is provided in which resin powder is applied to a non-impregnated or raw kraft paper layer immediately before a CPL line.

[0020] A non-impregnated or raw kraft paper layer is a kraft paper layer with a weight of up to 200 g / m 2 which are not impregnated with an impregnating resin, in particular a formaldehyde resin, such as melamine, urea and / or phenol-formaldehyde resin, or other resins, such as melamine ether resins, acrylic resins, epoxy resins and thus consist only of cellulose fibres

[0021] The inventive sprinkling of resin powder onto a raw, non-impregnated kraft paper layer and subsequent pressing with another paper layer at temperatures up to 200°C causes the resin powder to melt. The molten resin powder penetrates at least partially into the raw kraft paper layer and, if applicable, into the other paper layer, resulting in corresponding impregnation.

[0022] As explained in detail later, additional paper layers placed on top of the sprinkled raw kraft paper layer can be another kraft paper layer, a decorative paper layer or an overlay paper layer.

[0023] As also explained below, decorative paper is typically understood to be paper impregnated with a resin and printed with a decorative pattern. Overlay paper is understood to be paper impregnated with resin and equipped with abrasion-resistant particles. Melamine-formaldehyde resins are commonly used as impregnating resins, which typically exist as precondensates after impregnation. These low-molecular-weight precondensates still contain free methylol groups and a low degree of crosslinking, thus representing a polymerization intermediate. This state of the condensation resin in liquid-impregnated paper layers is also defined as state B of the resin or condensate.As indicated, the aim of the present process is not to use kraft papers that are already impregnated for laminate production as usual, but rather to use them as raw paper and to sprinkle them with dry powdery resin directly before a high-pressure press.

[0024] Together with the other named paper layers, such as a covering kraft paper, a decorative paper (impregnated), and an overlay paper (impregnated), such a stack is pressed under high pressure and high temperature, so that the resins first liquefy and then condense, thus forming a laminate. During the condensation step, the curable precondensates (state B) contained in the impregnates are converted into cured polycondensates (state C) by splitting off the remaining methylol groups. Such high-pressure laminates are then applied, usually by adhesive, to various substrates.

[0025] As will be described in more detail later, the resin powder can be applied to the raw kraft paper layer using spreaders that sprinkle the resin or resin mixture, with or without additives, onto the raw kraft paper. The application quantities can be changed / adjusted within minutes by changing the rotation speed. The spreader can be adjusted so that there is no resin in the edge areas. It is also possible to change the spreading width from, for example, 1340 mm to 2070 mm. Furthermore, a desired property can be created by adding additives (flame retardants, agents to increase conductivity, color pigments, etc.). A key point here is that a spreader can spread very precisely (+ / - 1% across the web width). It is also possible to react by increasing or decreasing the application quantity if quality problems become apparent or if there are changes to the application quantity.In addition, the ratio between the phenolic resin and melamine resin powder can be quickly adjusted to the process. The same applies to the addition of additives. If different properties are desired, this can be quickly adjusted using the mixing device. Of course, other products available in web form can also be used, even if they pose problems during impregnation. These problems can include the precise adjustment of the resin application, thorough impregnation, or handling on the impregnation line, among other things. This process also allows the use of precursors that are not available as web products or whose production as web products is uneconomical. These include glass fiber mats, graphite-containing papers, plastic films, aluminum foil, or veneers.Since CPL systems typically only produce relatively thin products (thickness < 1.0 mm), which means that two or three raw kraft paper layers are used, two spreaders are sufficient for production. Pure melamine resin can, of course, also be applied to the top raw kraft paper (e.g., BNPK), so that a further paper layer placed on top (such as decorative paper) can be used without impregnation. Since the powders contain little to no moisture, the desired moisture content can be achieved by vaporizing the NNP before the spreaders.

[0026] This process therefore offers several advantages. For example, the laminate production process can be designed flexibly. The application quantity can be quickly adjusted. Minimal fluctuations in the process allow for cost savings. This process also eliminates several work steps that are required with conventional liquid impregnation, such as passing the paper layer through an impregnation bath and subsequent drying.

[0027] Furthermore, it should be emphasized that the step of applying the resin powder to a kraft paper layer is preferably integrated into a continuous CPL production line; ie, the step of applying the resin powder is preferably carried out on a moving kraft paper layer.

[0028] The scattering of powder in the production of multi-layer boards or panels is known in various combinations. For example, according to EP 3144449B1, a powder mixture of thermosetting resins and wood or stone particles is scattered onto a carrier board made of compacted wood wool. US Pat. No. 10,513,094 B2 describes the scattering of a powder mixture of waste paper particles and a binder onto a wood-based panel, such as MDF or HDF. In these cases, the scattering of powder mixtures onto compact carrier boards is described.

[0029] The kraft paper layers used here have a weight between 50 and 200 g / m 2 , preferably between 80 and 170 g / m 2 , particularly preferably between 80 and 160 g / m 2 , such as 80 g / m 2 , 120 g / m 2 or 160 g / m 2As mentioned above, kraft papers are highly durable and consist of cellulose fibers to which starch, alum, and glue are added to create surface effects and increase strength.

[0030] In a further variant of the present method, the surface or side of the raw kraft paper layer to be sprinkled with the powdered resin is pretreated before sprinkling the powdered resin to improve the adhesion of the powdered resin to the surface of the raw kraft paper layer. This pretreatment can involve exposing the side or surface to moisture or electrostatically charging the side or surface of the kraft paper layer.

[0031] In one embodiment of the present method, the at least one raw kraft paper layer is moistened before being sprinkled with the powdered resin. For moistening, water is applied to a kraft paper layer in an amount of between 10 g water / m 2 and 40 g water / m 2 , e.g. between 10-20 g water / m 2 , between 15-30 g water / m 2 and / or between 20-40 g water / m 2 upset.

[0032] The amount of water applied / sprayed varies depending on the paper weight (grammage) and the moisture content of the kraft paper used. For kraft paper with a paper weight of 80 - 100 g / m 2 the amount of water sprayed is between 10 - 20 g water / m 2 for kraft paper with a paper weight of 110 — 130 g / m 2 the amount of water sprayed is between 15 - 30 g water / m 2and for kraft papers with a paper weight of 150 - 170 g / m 2 the amount of water sprayed is between 20 - 40 g water / m 2 be

[0033] Another option is to fix the powder to the kraft paper layer using electrostatic charging. The powder can be electrostatically charged and applied to the kraft paper layer. A counter electrode is located beneath the paper web to ensure good fixation to the paper.

[0034] In one embodiment of the present process, the powdered resin to be applied is a formaldehyde resin, preferably a melamine-formaldehyde resin or a phenol-formaldehyde resin, or a mixture of a melamine-formaldehyde resin and a phenol-formaldehyde resin. When using a mixture of phenol-formaldehyde resin and melamine-formaldehyde resin, the ratio of the two resins is 4:1, preferably 3:2. The two resins are preferably mixed in a mixing device before being sprinkled onto the kraft paper layer.

[0035] The particle size of the powdered resin is between 20 and 100 pm, preferably between 40 and 80 pm.

[0036] In one embodiment of the present process, the powdered resin or resin mixture is used in an amount of 50 to 350 g / m 2 , preferably 100 to 300 g / m 2 , particularly preferably from 120 to 280 g / m 2, most preferably 150 to 250 g / m 2 applied to at least one layer of kraft paper.

[0037] The powdered resin is preferably applied using at least one spreading device. The number of spreading devices upstream of the CPL system can be flexibly adjusted. Spreading is preferably carried out in a continuous process. A suitable spreading device is the precision spreader "Oscillating Brushing System" from TPS. However, electrostatic application with a tribo-gun is also possible.

[0038] The spreader's spreading width can also be adjusted as desired. For example, it's advantageous not to sprinkle resin on the edges of the kraft paper layers (e.g., the outer two centimeters), which prevents the resin from leaking out during subsequent pressing.

[0039] The spreading density is selected so that the resin application is between 70 and 90 wt%, preferably between 75 and 85 wt% based on two kraft paper layers, e.g. 75 wt%, 77 wt% or 85 wt%.

[0040] As already mentioned, at least one additional paper layer is placed on top of the kraft paper layer sprinkled with the resin powder. Any number of paper layers can be applied, although two, three, or four additional paper layers are preferred.

[0041] As mentioned above, the at least one additional paper layer to be applied can be a kraft paper layer, a decorative paper layer or an overlay paper layer.

[0042] Preferably, a further layer of kraft paper is applied, which is also not impregnated, i.e. is in its raw state.

[0043] In the further construction, the additional kraft paper layer is followed by an (impregnated) decorative paper layer and / or (impregnated) overlay paper layer. The possible layer or cover structures are described in detail below. It is also conceivable that a raw decorative paper layer is used.

[0044] As stated, the decorative and overlay paper layers used can be completely saturated (impregnated) with a resin, preferably melamine-formaldehyde resin. In the case of a completely impregnated paper, a resin quantity of 80-400 wt%, preferably 90-120 wt%, particularly preferably 100-110 wt%, based on the paper weight of the paper is applied.

[0045] Overlay papers are thin papers that are typically already impregnated with a conventional melamine resin. Overlay papers are also available in which abrasion-resistant particles, such as corundum particles, are mixed into the overlay resin or sprinkled onto the resin-coated overlay to increase abrasion resistance. Resin coatings with up to 400 wt% melamine resin are used to impregnate overlay papers. For most applications (laminates for countertops or payment counters), overlays without corundum are sufficient.

[0046] Decorative papers are specialty papers for surface finishing of wood-based materials, allowing for a wide variety of decorative designs. In addition to the typical prints of various wood textures, more sophisticated prints of geometric shapes or artistic products are available. There are virtually no restrictions on the choice of motifs. To ensure optimal printability, the paper used must have a suitable smoothness and dimensional stability and also be suitable for penetration of the necessary synthetic resin impregnation. The resin application for decorative impregnated papers is between 100 and 120% by weight.

[0047] In a further embodiment, at least one layer of a coating material is first applied to the side of the raw kraft paper layer sprinkled with the powdered resin, followed by at least one of the additional paper layers. It is also possible to sprinkle resin powder onto the material layer before the at least one additional paper layer is applied to the material layer.

[0048] In one variant, a material layer (e.g., glass fleece) is placed on the side of the kraft paper layer sprinkled with the resin powder, followed by a second kraft paper layer, a decorative paper layer, and / or an overlay paper layer. In another variant, a material layer (e.g., aluminum foil) is placed on the side of the kraft paper layer sprinkled with the resin powder, onto which resin powder is also sprinkled, followed by a second kraft paper layer, a decorative paper layer, and / or an overlay paper layer.

[0049] However, it is also possible to omit a second kraft paper layer and / or decorative paper layer and apply an overlay paper layer directly onto the material layer. The type and order of the additional paper layers can be flexibly designed depending on the type of porous material layer. If the porous material layer is colored, for example, decorative paper can be omitted.

[0050] The at least one coating material can be selected from the following materials: a veneer layer, graphite-containing papers to increase conductivity, plastic films, especially thermoplastic films (enabling tight postforming radii), aluminum foil, nonwoven material, and other fabric materials. The coating materials used can either be porous or non-porous, i.e., impermeable to liquids. In particular, materials are included that have a porosity in which liquid resin can rise during compression and that are at least partially plastically deformable.

[0051] The use of a glass fiber mat improves impact resistance. Even with thin laminates (< 1 mm), impact resistance of 25-25 N, preferably 28-32 N, e.g., 29 N, can be achieved.

[0052] The use of aluminum foil, preferably primed with an isocyanate primer before application, reduces water vapor permeability. The thickness of the aluminum foil is 0.1–0.3 mm, preferably 0.2 mm.

[0053] In the case of the use of a veneer layer, in one embodiment this comprises at least one layer of real wood veneer.

[0054] In a further embodiment, the at least one veneer comprises at least one real wood layer with a thickness between 0.2-10 mm, preferably 0.5-5 mm, particularly preferably 0.5-2 mm. The veneer can be produced in one piece from a trunk, for example, by peeling. However, it can also be composed of individual pieces that are connected to one another, for example, by binding agents or so-called glue threads. The veneer preferably has the dimensions of the carrier board. The veneer has an underside facing the carrier board and an upper side facing away from the carrier board.

[0055] In a further embodiment of the present method, the layered structure of kraft paper layer and at least one further paper layer is pressed with at least one structuring paper (placed on the at least one further paper layer on the upper side of the layering) and at least one transparent paper (on the underside of the layering).

[0056] A structuring paper is a paper that, after being applied and pressed, imparts a structure (e.g., a 3D structure) to the surface of the laminate. In addition to its structuring function, the structuring paper also serves a protective function, particularly during the pressing step. The structuring paper is removed after the layer or cover structure has been pressed and can be recycled.

[0057] The tracing paper used in this laminate is also known as glassine. Glassine is a tracing paper made from finely ground pulp that is largely greaseproof but not water-resistant. It achieves its high transparency through a very sharp calendering process.

[0058] It is also possible to use a non-impregnated paper on the underside. If only about half of the powdered resin is used for this paper, sanding the laminate on the back after pressing is not necessary.

[0059] It is also conceivable to apply an additional backing paper to the underside of the laminate to stabilize the laminate. Backing papers are high-quality, impregnated papers used as backing material, for example, for single-sided surface veneers and other single-sided coatings.

[0060] In a further preferred embodiment of the present process, an additive, in particular a flame retardant, is added to the powdered resin.

[0061] Acetoguanamine, ammonium polyphosphate, and tris(tribromoneopentyl)phosphate can be used as flame retardants. The ratio of flame retardant to resin powder is preferably 1.5 to 5.

[0062] In a further variant of the present process, the layer structure consisting of the side of the kraft paper layer sprinkled with the powdered resin, optionally at least one porous material layer, at least one further paper layer, in particular a kraft paper layer, decorative paper layer and / or overlay paper layer, optionally a structuring agent, optionally a transparent paper and optionally a counter-pressure layer is pressed in a hot press, in particular in a continuous press or in a double-belt press. The pressing step in the press (CPL press) is carried out at an applied pressure of between 50 - 70 kg / cm 2 and a temperature between 150 and 200°C, preferably 180°C. The press speed is 5-20 m / min, preferably 5 to 15 m / min, e.g., 9.5 m / min. The laminate produced in the press has a thickness between 0.15 and 1.2 mm.

[0063] The present method enables the provision of a laminate (or cover), in particular a CPL, which has at least one resin-impregnated kraft paper layer as core layer and further paper layers, in particular kraft paper layer, decorative paper layer and / or overlay paper layer.

[0064] In one variant, the laminate comprises at least one overlay paper layer, at least one decorative paper layer, and at least two kraft paper layers. Such a layer structure can be as follows from top to bottom: overlay paper layer, one decorative paper layer, a first kraft paper layer, and a second kraft paper layer.

[0065] In another variant, the laminate comprises at least one overlay paper layer, at least one decorative paper layer, at least two kraft paper layers, and at least one transparent paper. Optionally, at least one backing layer can be provided. Such a layer structure can look like this from top to bottom: overlay paper layer, one decorative paper layer, a first kraft paper layer, a second kraft paper layer, and a transparent paper (glassine layer).

[0066] In a further variant, the laminate comprises at least one structural element, at least one overlay paper layer, at least one decorative paper layer, at least two kraft paper layers, and at least one transparent paper. Optionally, at least one counterlayer can be provided. Such a layer structure can be as follows from top to bottom: structural element, overlay paper layer, one decorative paper layer, a first kraft paper layer, a second kraft paper layer, and a transparent paper (glassine layer).

[0067] In a further variant, the laminate that can be produced using the present method optionally comprises at least one structuring agent, at least one overlay paper layer, at least one decorative paper layer, at least two kraft paper layers and at least one transparency paper, with at least one flame retardant being provided between the two kraft paper layers. In an even more extensive variant, the laminate that can be produced using the present method optionally comprises at least one structuring agent, at least one overlay paper layer, at least one decorative paper layer, at least two kraft paper layers, at least one layer of a (porous) coating material, in particular glass fleece or aluminum foil, and at least one transparency paper. Optionally, at least one counterlayer can be provided. Such a layer structure can look like this from top to bottom: if applicable.a structure-forming element, an overlay paper layer, a decorative paper layer, a first kraft paper layer, a layer of a coating material, in particular glass fleece or aluminum foil, and a second kraft paper layer and a transparency paper (glassine layer).

[0068] In yet another variant, the laminate producible using the present method optionally comprises at least one structuring agent, at least one overlay paper layer, at least one kraft paper layer, at least one layer of a (porous) coating material, in particular a veneer, and at least one transparent paper. Optionally, at least one counterlayer can be provided. Such a layer structure can be as follows from top to bottom: optionally, a structuring agent, an overlay paper layer, a layer of a (porous) coating material, in particular a veneer, a kraft paper layer, and a transparent paper (glassine layer).

[0069] The counter-tension mentioned in the above embodiments of the laminate is taken up as and when required.

[0070] The present laminate or deck has a construction height with a thickness between 0.1 and 3 mm, preferably between 0.1 and 1.2 mm.

[0071] The invention is explained in more detail below using several exemplary embodiments.

[0072] For the following examples, the powder resins BASF 630 (melamine resin) and Prefere 82 8583G0 (phenolic resin) were used.

[0073] Example 1:

[0074] An 80 g / m 2 NKP (width: 1340 mm) was unwound from a roll on a CPL system. A humidification system was used to add approximately 10 g of water / m 2sprayed onto the kraft paper (top side). Immediately before the press, a mixture of phenolic and melamine resin was sprinkled onto the NKP. The ratio of phenolic to melamine resin was 3 to 2. The resins were mixed in a mixer and then fed into the sprinkler. The application rate was 136 g of resin mixture per m². 2 (Resin application: 85% based on two NKP).

[0075] The spreader was adjusted so that the outer two centimeters of the web were not sprinkled with resin powder on both sides. A second NKP layer of the same grammage was applied to the kraft paper via an unwinder. A decorative and overlay impregnated resin with the usual resin and moisture content were then applied on top.

[0076] This structure was created with a structure on the top and a parchment

[0077] (60 g / m 2) on the underside at a speed of 9.5 m / min through the system. The pressing temperature was 180°C, the pressing pressure 60 kg / cm 2 No resin leakage was observed at the edge after the press. The resulting laminate was trimmed and rolled up.

[0078] The laminate was then tested according to DIN EN 438 against a laminate manufactured with impregnated NKP for several key parameters (water vapor test, postforming properties, scratch test). No differences were found between the two laminates.

[0079] Example 2:

[0080] NKP in a grammage of 80, 120 and 160 g / m 2 (Width: 1340 mm) were unwound from a roll on a CPL system. A humidification system was used to add approximately 10 - 20 g of water / m 2 (80 g NKP), 15-30 g water / m 2 (120 g NKP) and 20 - 40 g water / m 2(160 g NKP) sprayed onto the top.

[0081] Immediately before the press, a mixture of phenolic and melamine resin was sprinkled onto the NKP. The ratio of phenolic to melamine resin was 3 to 2. The resins were mixed in a mixer and then fed to the sprinkler. The application quantities were 136 g (80 g / m 2 ), 204 g ( 120g / m 2 ) and 272 g ( 160 g / m 2 ) Resin mixture / m 2 (Resin application: 85% based on two resin powder coatings). The spreader was adjusted so that the outer two centimeters of the web were not sprinkled with resin powder on both sides. A second resin powder coating layer of the same grammage was applied to the kraft paper via a spool. A decorative and overlay impregnated coating with the usual resin and moisture content was then applied on top.

[0082] This structure was created with a structure on the top and a parchment (60 g / m 2) on the underside at a speed of 9.5 m / min through the system. The pressing temperature was 180°C, the pressing pressure 60 kg / cm 2 No resin leakage was observed at the edge after the press. The resulting laminate was trimmed and rolled up.

[0083] The laminates were then tested according to DIN EN 438, Part 2, "12. Resistance to immersion in boiling water." The focus was on assessing delamination due to poor resin distribution / penetration. The results are listed in Table 1. For a laminate with resin-coated NKP produced using the standard impregnation process, neither blistering nor delamination is typically observed during the "boiling water immersion" test.

[0084] Table 1

[0085] Example 3:

[0086] NKP in a grammage of 80, 120 and 160 g / m2 (Width: 1340 mm) were unwound from a roll on a CPL system. A humidification system was used to add approximately 10 - 20 g of water / m 2 sprayed onto the kraft paper (top side). Immediately before the press, a mixture of phenolic and melamine resin was sprinkled onto the NKP. The ratio of phenolic to melamine resin was 3 to 2. The resins were mixed in a mixer and then fed to the sprinkler. The application quantities were 122 g (80 g / m 2 ), 180 g ( 120g / m 2 ) and 245 g ( 160 g / m 2 ) Resin mixture / m 2 (Resin application: 77% based on two NKP).

[0087] The spreader was adjusted so that the outer two centimeters of the web were not sprinkled with resin powder on both sides. A second NKP layer of the same grammage was applied to the kraft paper via an unwinder. A decorative and overlay impregnated resin with the usual resin and moisture content were then applied on top.

[0088] This structure was created with a structure on the top and a parchment (60 g / m 2 ) on the underside at a speed of 9.5 m / min through the system. The pressing temperature was 180°C, the pressing pressure 60 kg / cm 2 No resin leakage was observed at the edge after the press. The resulting laminate was trimmed and rolled up.

[0089] The laminates were then tested according to DIN EN 438, Part 2, "12. Resistance to immersion in boiling water." The primary focus was on assessing delamination due to poor resin distribution / penetration. The results are listed in Table 2. For a laminate with resin-coated NKP produced using the standard impregnation process, neither blistering nor delamination is typically observed during the "boiling water immersion" test.

[0090] Table 2: As can be seen from the results, the resin application can be reduced by 10% without any noticeable loss of quality. Surprisingly, the mass increase of the impregnated laminates with less resin application is lower than that of the laminates with higher resin application.

[0091] Example 4:

[0092] A 165 g / m 2NKP (width 1340 mm) was unwound from a roll on a CPL system. A humidification system was used to add approximately 20–40 g of water / m 2 sprayed onto the kraft paper (top side).

[0093] Immediately before the press, a mixture of flame retardant (acetoguanamine), phenolic resin, and melamine resin was sprinkled onto the NKP. The ratio of guanamine, phenolic resin, and melamine resin was 1.5 to 3 to 2. The application rate was 316 g resin + flame retardant / m 2 (Resin application: 75% based on two NKP).

[0094] The spreader was set so that the outer 2 cm of the web was not sprinkled with resin powder. A second NKP layer of the same grammage was applied to the kraft paper via an unwinder. A decorative and overlay impregnated resin with the usual resin concentration and moisture content were then applied on top.

[0095] This structure was created with a structure on the top and a parchment (60 g / m 2 ) on the underside at a speed of 9.5 m / min through the system. The pressing temperature was 180°C, the pressing pressure 60 kg / cm 2 .

[0096] The resulting laminate was rolled up. The laminate was then tested according to DIN EN 13 501-1:2018 (classification of fire behavior). The result c - s1, dO was achieved.

[0097] Example 5:

[0098] An 80 g / m 2 NKP (width: 1340 mm) was unwound from a roll on a CPL system. A humidification system was used to add approximately 10 g of water / m 2sprayed onto the kraft paper (top side). Immediately before the press, a mixture of phenolic and melamine resin was sprinkled onto the NKP. The ratio of phenolic to melamine resin was 3 to 2. The resins were mixed in a mixer and then fed into the sprinkler. The application rate was 136 g of resin mixture per m². 2 (Resin application: 85% based on two NKP).

[0099] The spreader was adjusted so that the outer two centimeters of the fabric were not sprinkled with resin powder on both sides. A glass fleece (grammage: 110 g / m²) was applied to the kraft paper. 2 ) and also 136 g / m 2 Resin was sprinkled on. The glass fleece served to improve impact resistance. A second NKP layer of the same grammage was applied to the fleece via a unwinding process. A decorative and overlay impregnated layer with the usual resin and moisture content was then applied on top.

[0100] This structure was created with a structure on the top and a parchment (60 g / m 2 ) on the underside at a speed of 9.5 m / min through the system. The pressing temperature was 180°C, the pressing pressure 60 kg / cm 2 No resin leakage was observed at the edge after the press. The resulting laminate was trimmed and rolled up.

[0101] The laminate was then tested for several important parameters (water vapor test, scratch test) in accordance with DIN EN 438, comparing it with a laminate manufactured with impregnated NKP. No differences were found between the two laminates. To test the laminate bond, the laminate was immersed in hot water for 2 hours. No blistering or delamination was observed. Water absorption was 5.5%. In the impact resistance test according to DIN EN 438 - TI. 20 "small ball," a value of 22 N was determined for the laminate without glass fiber mat and 29 N for the laminate with glass fiber mat.

[0102] Example 6:

[0103] An 80 g / m 2 NKP (width: 1340 mm) was unwound from a roll on a CPL system. A humidification system was used to add approximately 10 g of water / m 2sprayed onto the kraft paper (top side). Immediately before the press, a mixture of phenolic and melamine resin was sprinkled onto the NKP. The ratio of phenolic to melamine resin was 3 to 2. The resins were mixed in a mixer and then fed into the sprinkler. The application rate was 68 g of resin mixture per m². 2 (Resin application: 85% based on two NKP).

[0104] The spreader was adjusted so that the outer two centimeters of the fabric were not sprinkled with resin powder on both sides. A 0.2 mm aluminum foil, primed on both sides to reduce water vapor permeability, was unrolled onto the kraft paper and also applied at 68 g / m 2 Resin was sprinkled on. A second NKP layer of the same grammage was applied to the aluminum foil via a unwinding process. A decorative and overlay impregnated resin was then applied on top, with the usual resin and moisture content.

[0105] This structure was created with a structure on the top and a parchment (60 g / m 2 ) on the underside at a speed of 9.5 m / min through the system. The pressing temperature was 180°C, the pressing pressure 60 kg / cm 2 No resin leakage was observed at the edge after the press. The resulting laminate was trimmed and rolled up.

[0106] Example 7:

[0107] An 80 g / m 2 NKP (width: 1340 mm) was unwound from a roll on a CPL system. A humidification system was used to add approximately 10 g of water / m 2 sprayed onto the kraft paper (top side).

[0108] Immediately before the press, a mixture of phenolic and melamine resin was sprinkled onto the NKP. The ratio of phenolic to melamine resin was 3 to 2. The resins were mixed in a mixer and then fed to the sprinkler.

[0109] The application quantity was 210 g resin mixture / m 2 (Resin application: 85% based on two NKPs). The spreader was adjusted so that the outer two centimeters of the web were not sprinkled with resin powder on both sides. An oak veneer (thickness: 0.5 mm) measuring 1400 x 1340 mm was applied to the kraft paper. An overlay impregnated with the usual resin and moisture content was applied on top.

[0110] This structure was created with a structure on the top and a parchment (60 g / m 2 ) on the underside at a speed of 9.5 m / min through the system. The pressing temperature was 180°C, the pressing pressure 60 kg / cm 2 The resulting laminate showed no delamination. Transparency was good.

Claims

Patent claims 1. A process for producing a laminate comprising at least one kraft paper layer, comprising the following steps: Providing at least one raw or non-impregnated kraft paper layer, - applying at least one first layer of at least one powdered resin to at least one side of the kraft paper layer, - placing at least one further paper layer on the side of the kraft paper layer sprinkled with the powdered resin, and - Pressing the layer structure.

2. Method according to claim 1, characterized in that the at least one raw kraft paper layer has a weight between 50 and 200 g / m 2 , preferably between 80 and 170 g / m 2 , particularly preferably between 80 and 160 g / m 2 , most preferably between 80 and 120 g / m 2 has.

3. Method according to one of the preceding claims, characterized in that the at least one raw kraft paper layer is moistened before being sprinkled with the powdered resin.

4. A method according to claim 3, characterized in that for moistening, water is applied to a raw kraft paper layer in an amount between 10 g water / m 2 and 40 g water / m 2 , e.g. between 10 - 20 g water / m 2 , between 15 - 30 g water / m 2 and / or between 20 - 40 g water / m 2 is applied.

5. Process according to one of the preceding claims, characterized in that the powdered resin is a formaldehyde resin, preferably a melamine-formaldehyde resin or a phenol-formaldehyde resin or a mixture of a melamine-formaldehyde resin and a phenol-formaldehyde resin.

6. Process according to one of the preceding claims, characterized in that the powdered resin is used in an amount of 50 to 350 g / m 2 , 100 to 300 g / m 2 , preferably from 120 to 280 g / m 2 , particularly preferably 150 to 250 g / m 2 onto which at least one layer of kraft paper is applied.

7. Method according to one of the preceding claims, characterized in that the at least one further paper layer to be applied is a kraft paper layer, a decorative paper layer or an overlay paper layer, preferably a raw kraft paper layer.

8. Method according to one of the preceding claims, characterized in that at least one layer of a coating material is first applied to the side of the raw kraft paper layer sprinkled with the powdered resin, followed by the at least one further paper layer.

9. Method according to claim 8, characterized in that Coating material layer a veneer layer, a graphite-containing paper, Plastic film, aluminum foil, nonwoven material and other fabric materials can be used.

10. Method according to one of the preceding claims, characterized in that the layer structure of raw kraft paper layer and at least one further paper layer is pressed with at least one structuring paper (placed on the at least one further paper layer on the upper side of the layer) and at least one transparent paper (on the underside of the layer). 11 . Process according to one of the preceding claims, characterized in that an additive, in particular a flame retardant, is added to the powdered resin.

12. Method according to one of the preceding claims, characterized in that the layer structure consisting of the side of the raw kraft paper layer sprinkled with the powdered resin, optionally at least one coating material layer, at least one further paper layer, in particular a kraft paper layer, decorative paper layer and / or overlay paper layer, optionally a structure provider, optionally a transparent paper and optionally a counter-sheet is pressed in a hot press, in particular in a continuous press or in a double-belt press.

13. Laminate producible in a process according to one of the preceding claims, comprising at least one decorative paper layer, at least two kraft paper layers and at least one transparency paper, wherein at least one flame retardant is provided between the two kraft paper layers.

14. A laminate producible by a process according to any one of the preceding claims, comprising at least one overlay paper layer, at least one decorative paper layer, at least two kraft paper layers, at least one layer of a coating material, in particular a glass mat, and at least one transparency paper.

15. A laminate producible by a process according to any one of the preceding claims, comprising at least one overlay paper layer, at least one kraft paper layer, at least one layer of a coating material, in particular a veneer, and at least one transparency paper.

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