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

Abstract

The invention relates to a method for producing a laminate comprising at least one kraft paper layer, comprising the following steps: providing at least one unprocessed kraft paper layer, applying at least one first layer made of at least one powdered resin to at least one side of the kraft paper layer, at least one further paper layer is placed on the side of the kraft paper layer dispersed with the powdered resin, and the layer construction is pressed.

Description

Technical Field

[0001] The invention relates to a method for producing a laminate comprising at least one kraft paper layer and at least one further paper layer, and to a laminate producible by means of said method. Background Art

[0002] Laminates are layer materials consisting of paper impregnations pressed together and applied (adhesively) to a carrier sheet. Laminates are currently known in the prior art, for example, in which the layer composite comprises at least one impregnated paper layer, for example a decorative impregnation, at least one transparent paper layer (cellophane), for example cellophane treated with sulfuric acid, and / or at least one plastic film layer.

[0003] A distinction is made between High Pressure Laminate (HPL) and Continuous Pressure Laminate (CPL). HPL is a sheet-shaped laminate made of multiple layers of paper and resin, produced in a high-pressure pressing process, which is produced in a laminating machine. CPL is produced in a continuous process from multiple layers of paper and resin. It is mostly available as a roll and is used, for example, for the production of work panels, clad profiles and door panels. CPL is pressed in a continuous or circular process in a roll-to-roll press that is heated on both sides. In both HPL and CPL, kraft paper is used as at least one paper layer. Kraft paper has a density of up to 200 g / m². 2 It has high strength for its weight and is composed of cellulose fibers with starch, alum and glue added to achieve surface effects and increased strength.

[0004] When manufacturing CPL on a double-belt press, a resin-impregnated kraft paper layer in the form of sodium hydroxide kraft paper (NKP) is used in the core layer, as with HPL. While HPL typically uses NKP impregnated with phenolic resin, CPL typically uses NKP containing a mixture of melamine and phenolic resins. The resin coating for HPL kraft paper in the core layer is typically 40 to 50% by weight. For CPL core layers, the resin coating is 80 to 90% by weight.

[0005] The impregnation of the kraft paper takes place on an impregnation tunnel, which in some cases runs at speeds >100 m / min. The impregnation for kraft paper-based HPL is produced as a sheet, while the impregnation for kraft paper-based CPL is produced as a coil. This also applies to the other impregnations used in CPL plants (decorative impregnations, covering impregnations, or counter impregnations). Working with sheet products is only done in special cases.

[0006] Because the roll can have a length of hundreds of meters depending on the paper weight, it shows considerable product value. However, when producing the roll, quality determination (final weight, resin coating, humidity) can only be performed at the end of the roll. However, this cannot account for the humidity and resin coating in the roll. Fluctuations in the process (temperature of the impregnating resin and NKP, temperature in the production workshop, temperature fluctuations in the drying tunnel, etc.) or fluctuations in the raw materials (gram weight, paper humidity, etc.) may produce impregnated rolls that cause problems at the CPL facility. This can be, for example, delamination, warping, etc. Although the process can be monitored by installing online analysis (near infrared spectroscopy, microwaves, etc.), there is still the problem that due to the high production speed, a large number of impregnations with quality defects will still be produced because there are still several minutes of production time between detection and correction.

[0007] Furthermore, many CPL manufacturers do not manufacture the impregnated kraft paper layers used in their core layers themselves, as fast-running impregnation tunnels often have significantly greater impregnation capacity than can be processed on one or two CPL plants. However, for contamination reasons, processing phenolic resins in the impregnation tunnels is not possible, nor can the decorative paper or cover layers be impregnated with melamine resin. This is not feasible even after extensive cleaning of the tunnels. Consequently, CPL manufacturers rely on the commercially available impregnation quality of the kraft paper layers. If this causes problems at the CPL manufacturer's facilities, the manufacturer can only correct the defects by changing the plant parameters (temperature, plant speed, and pressure). A particular disadvantage is that the impregnation material is often delivered via full truckloads. This leaves manufacturers with a large number of rolls in their warehouses, which can only be tested for their usability in production using a "trail and error" method.

[0008] Furthermore, it is often problematic to add additives to the dipping bath to produce specific product properties. Some additives are poorly water-soluble, and their addition sometimes causes segregation in the dipping tank. This complicates the dipping process and makes producing the desired properties difficult or even impossible.

[0009] Furthermore, the entire width of the product is always impregnated during dipping. This can subsequently lead to contamination of the press belt / structure supply by resin emerging at the edges under the pressures and temperatures of the CPL facility. Attempts have been made to address this problem by applying solvent to the edges before the dipping tank. However, the amount and positioning of the nozzles must be monitored. Furthermore, due to the high speeds, the time between application and immersion in the dipping tank is relatively short, making it impossible to achieve good impregnation of the edge areas.

[0010] There are various disadvantages. Therefore, it is difficult to determine the quality of the roll, and the distribution of properties can change. Impregnation of the edge areas is also problematic, and water-insoluble additives cannot be used during impregnation. Summary of the Invention

[0011] The technical purpose on which the present invention is based is therefore to overcome the above-mentioned disadvantages. It is particularly desirable to provide a solution in which the impregnation of the kraft paper layer is carried out directly on site at the CPL manufacturer, thereby not having to rely on the supply of already impregnated kraft paper layers with the above-mentioned disadvantages. Here, the low demand of a single CPL facility should also be taken into account. It should also be possible to adjust the impregnated kraft paper layer with respect to resin coating, humidity or other parameters quickly and precisely. In addition, it should also be simple and feasible to add additives to achieve resin / product properties. In addition, it should also be possible to use powdered / fibrous fillers (cellulose, powder, inorganic and organic fibers, etc.). Adaptation to different product widths should also be possible quickly and avoid material losses.

[0012] This object is achieved by a method having the features of claim 1 .

[0013] Correspondingly, a method for producing a laminate, in particular a CPL, comprising at least one kraft paper layer is provided, wherein the method comprises the following steps:

[0014] - providing at least one unimpregnated or unprocessed kraft paper layer,

[0015] - applying at least one first layer consisting of at least one powdered resin to at least one side of the kraft paper layer,

[0016] - placing at least one further paper layer onto the side of the kraft paper layer sprinkled with the powdered resin, and

[0017] - Compact the layer structure.

[0018] Therefore, a multi-stage process is provided in which the resin powder is applied to an unimpregnated or untreated kraft paper layer directly before the CPL facility.

[0019] Unimpregnated or unprocessed kraft paper layers are understood to have a density of up to 200 g / m 2 A kraft paper layer of a weight of 1000 wt %, which is not impregnated with an impregnation resin, in particular a formaldehyde resin, such as melamine-formaldehyde resin, urea-formaldehyde resin and / or phenol-formaldehyde resin, or other resins, such as melamine ether resin, acrylic resin, epoxy resin, and thus consists only of cellulose fibers.

[0020] According to the invention, resin powder is spread onto a raw, unimpregnated kraft paper layer and subsequently pressed against another paper layer at temperatures of up to 200° C., which causes the resin powder to melt. The molten resin powder at least partially penetrates the raw kraft paper layer and, if necessary, the other paper layer, causing corresponding impregnation.

[0021] As will be explained in more detail below, as further paper layers placed on the spread unprocessed kraft paper layer, further kraft paper layers, decorative paper layers or covering paper layers can be used.

[0022] As will also be explained in detail below, decor paper is typically understood to mean resin-impregnated paper with a printed decoration. Overlay paper is understood to mean resin-impregnated paper provided with wear-resistant particles. For this purpose, melamine-formaldehyde resin is commonly used as an impregnation resin, which is typically present as a precondensate after impregnation. The low-molecular-weight precondensate still has free methylol groups and a low degree of crosslinking, thus providing a polymeric intermediate. This state of the condensed resin in the liquid-impregnated paper layer is also designated as state B of the resin or condensate.

[0023] As already mentioned, the method according to the invention does not aim to use kraft paper, as is customary, which is already impregnated, for producing laminates, but rather to use it as base paper and to spread it with dry powdered resin only immediately before high-pressure pressing.

[0024] Together with the other mentioned paper layers, such as kraft paper for covering, decorative paper (impregnation), and overlay paper (impregnation), this stack is compressed under high pressure and high temperature, causing the resin to first liquefy and then condense to form a laminate. During the condensation step, the hardenable precondensate (state B) contained in the impregnation is converted into a hardened polymeric condensate (state C) by dissociating the methylol groups still present. This high-pressure laminate is then applied, usually adhesively bonded, to various supports.

[0025] As will be described in detail later, the application of resin powder to raw kraft paper is performed using a spreading device that spreads the resin or resin mixture with or without additives onto the raw kraft paper. The spreading amount can be varied / adjusted by changing the rotational speed within minutes. The spreading device can be set so that no resin is present in the edge areas. Changing the spreading width from, for example, 1340 mm to 2070 mm is also easily possible. Furthermore, the addition of additives (flame retardants, conductivity-enhancing agents, pigments, etc.) can produce the desired properties. A crucial point here is that the spreading device can spread very precisely (+ / - 1% across the product width). This allows for an upward or downward adjustment in the event of quality issues or changes in the coating amount. Furthermore, the ratio between phenolic resin powder and melamine resin powder can be quickly adapted to the process. The same applies to the addition of additives. If different properties are desired, this can be quickly adapted to the mixing equipment. Of course, other products available in strip form that may cause problems during impregnation can also be used. Problems can arise from precisely setting the resin coating, achieving complete impregnation, or handling at the impregnation line. The method also allows for the use of raw materials that are not suitable for use as strip products or whose production as strip products is uneconomical. These can include fiberglass mats, graphite-containing paper, plastic film, aluminum foil, or plywood. Since CPL facilities typically manufacture only relatively thin products (thickness <1.0 mm), this means using two or three layers of unprocessed kraft paper, so two spreading devices are sufficient for production. Of course, pure melamine resin can also be applied to the topmost unprocessed kraft paper (e.g., NKP), allowing the use of another unimpregnated paper layer (e.g., decorative paper) placed above it. Since the powder can contain little or no moisture, the desired humidity can be set by allowing the NKP to release water vapor before the spreading device.

[0026] The method of the present invention thus offers various advantages. The method for producing laminates can thus be designed flexibly. Rapid adjustment of the coating amount is possible. Cost savings are possible through small process changes. The method of the present invention also eliminates the need for multiple work steps associated with conventional liquid impregnation, such as guiding the paper layer through the impregnation bath and subsequent drying.

[0027] Furthermore, it is emphasized that the step of applying the resin powder onto the kraft paper layer is preferably integrated into the continuous CPL production line; that is, the step of applying the resin powder is preferably performed on a moving kraft paper layer.

[0028] The spreading of powders in the production of multi-layer boards or panels is known in various combinations. For example, according to EP 3144449 B1, a powder mixture consisting of thermoplastic resin and wood or stone particles is spread onto a carrier board made of compressed wood wool. US Pat. No. 10,513,094 B2 describes spreading a powder mixture consisting of particles made of waste paper and a binder onto wood-based panels such as MDF or HDF. In each case, the powder mixture is spread onto a compact carrier board.

[0029] The kraft paper layer currently used has a 2 and 200g / m 2 Between, preferably between 80g / m 2 and 170g / m 2 between, particularly preferably between 80g / m 2 and 160g / m 2 Between, for example 80g / m 2 , 120g / m 2 or 160g / m 2 As mentioned above, kraft paper has high strength and is composed of cellulose fibers with starch, alum and glue added to achieve surface effects and increased strength.

[0030] In a further variation of the method of the present invention, prior to spreading the powdered resin, the surface or side of the unprocessed kraft paper layer to be spread with the powdered resin is pretreated to improve adhesion of the powdered resin to the surface of the unprocessed kraft paper layer. The pretreatment may include subjecting the side or surface of the kraft paper layer to moisture or electrostatically charging the side or surface of the kraft paper layer.

[0031] Therefore, in one embodiment of the invention, at least one unprocessed kraft paper layer is moistened before being sprinkled with the powdered resin. For moistening, water is added at a rate of 10 g water / m 2 and 40g water / m 2 For example, 10g water / m 2 Up to 20g water / m 2 Between, 15g water / m 2 Up to 30g water / m 2 Between and / or 20g water / m 2 Up to 40g water / m 2 Apply an amount between 100 and 200 ml to the kraft paper layer.

[0032] The amount of water applied / sprayed here varies depending on the paper weight (grammage) and the humidity of the kraft paper used. Thus, for a paper weight of 80 g / m 2 Up to 100g / m 2 For kraft paper, the amount of water sprayed can be 10g water / m2 Up to 20g water / m 2 For paper weight of 110g / m 2 Up to 130g / m 2 For kraft paper, the amount of water sprayed can be 15g water / m 2 Up to 30g water / m 2 Between, and for paper weight of 150g / m 2 Up to 170g / m 2 For kraft paper, the amount of water sprayed can be 20g water / m 2 Up to 40g water / m 2 between.

[0033] Another option is to fix the powder to the kraft paper layer by electrostatic charging. Here, the powder can be electrostatically charged and applied to the kraft paper layer. A counter electrode is located beneath the paper strip, which ensures good fixation on the paper.

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

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

[0036] In one embodiment of the present method, a powdered resin or resin mixture is added at a rate of 50 g / m 2 Up to 350g / m 2 , preferably 100g / m 2 Up to 300g / m 2 , especially preferably 120g / m 2 Up to 280g / m 2 , very particularly preferably 150 g / m 2 Up to 250g / m 2 An amount of the adhesive is applied to at least one kraft paper layer.

[0037] The powdered resin is preferably applied using at least one spreading device. The number of spreading devices upstream of the CPL plant can be flexibly adjusted. Spreading is preferably performed in a continuous process. A suitable spreading device is the "Resonance Brush System," a precision spreading device from TPS. However, electrostatic application using a tribospray gun is also possible.

[0038] The spreading width of the spreading device can also be set arbitrarily. Therefore, it is advantageous that the edge areas of the kraft paper layer (for example the outer two centimeters) are not spread with resin, so that resin outflow during subsequent compaction can be avoided.

[0039] The spreading density is selected such that the resin coating, based on two kraft paper layers, is between 70% and 90% by weight, preferably between 75% and 85% by weight, for example 75%, 77% or 85% by weight.

[0040] As already mentioned, at least one further paper layer is placed onto the kraft paper layer dotted with resin powder. Any number of paper layers can be placed, with two, three or four further paper layers being preferred.

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

[0042] Preferably, a further layer of kraft paper is placed, which is likewise unimpregnated, ie is present in the raw state.

[0043] In another configuration, the additional kraft paper layer is followed by an (impregnated) decorative paper layer and / or an (impregnated) covering paper layer. Possible layer configurations or covering configurations will be described in detail further below. It is also conceivable to use an unprocessed decorative paper layer.

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

[0045] Overlay paper is typically a thin paper that has been impregnated with conventional melamine resin. Overlay paper is also available in which wear-resistant particles, such as corundum particles, have been incorporated into the resin of the overlay layer or have been applied to the resin-moistened overlay layer to increase the wear resistance. To impregnate the overlay paper, a resin coating containing up to 400% by weight of melamine resin is used. For most applications (laminates for workboards or cash registers), an overlay without corundum is sufficient.

[0046] Decorative paper is a specialized paper used for surface finishing of wood-based materials, enabling a high degree of decorative diversity. Thus, in addition to typical patterns for various wood structures, a wide range of geometric shapes or artistic products can be achieved. The choice of motifs is virtually unlimited. To ensure optimal printability, the paper used must possess appropriate smoothness and dimensional stability and also be suitable for the required synthetic resin impregnation. The resin coating used in the decorative impregnation ranges from 100% to 120% by weight.

[0047] In another embodiment, it is provided that at least one layer of the covering material is first placed on the side of the unprocessed kraft paper layer on which the powdered resin is spread, followed by at least one of the further paper layers. It is also possible to spread the resin powder on the material layer before placing the at least one further paper layer on it.

[0048] In one variation, a material layer (e.g., glass fiber mat) is placed on the side of the kraft paper layer where the resin powder is spread, followed by a second kraft paper layer, a decorative paper layer, and / or a cover paper layer. In another variation, a material layer (e.g., aluminum foil) is placed on the side of the kraft paper layer where the resin powder is spread, the resin powder is also spread on the material layer, followed by a second kraft paper layer, a decorative paper layer, and / or a cover paper layer.

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

[0050] The at least one coating material can be selected from the following: a facing layer, graphite-containing paper for increasing electrical conductivity, plastic films, particularly thermoplastic films (which enable narrow post-forming radii), aluminum foil, felt materials, and other textile materials. The coating material used can be porous or non-porous, i.e., impermeable to liquids. In particular, this includes porous materials in which liquid resin can rise during extrusion and which can at least partially plastically deform.

[0051] Glass fiber mats are used to improve the impact strength. Thus, by using glass fiber mats, even in the case of thin laminates (<1 mm), an impact strength of 25N to 25N, preferably 28N to 32N, for example 29N, can be achieved.

[0052] The water vapor permeability is reduced by using an aluminum foil which is preferably provided with a primer, for example an isocyanate primer, before placement. The thickness of the aluminum foil is 0.1 mm to 0.3 mm, preferably 0.2 mm.

[0053] In the case of using veneer boards, in one embodiment, the veneer layer includes at least one layer composed of solid wood veneer boards.

[0054] In a further embodiment, at least one veneer comprises at least one solid wood layer having a thickness of between 0.2 mm and 10 mm, preferably between 0.5 mm and 5 mm, and particularly preferably between 0.5 mm and 2 mm. The veneer can be manufactured from a tree trunk, for example, by peeling the bark in one piece. However, the veneer can also be made up of individual pieces, which are connected to each other, for example, by adhesive or so-called glue lines. The veneer preferably has the dimensions of a carrier board. The veneer has a lower side facing the carrier board and an upper side facing away from the carrier board.

[0055] In a further embodiment of the method, the layer construction consisting of a kraft paper layer and at least one further paper layer is pressed with at least one structural providing paper (placed on the at least one further paper layer on the upper side of the layer stack) and at least one transparent paper (on the lower side of the layer stack).

[0056] Here, a structure-providing paper is understood to be a paper that imparts structure (e.g., a 3D structure) to the surface of the laminate after placement and pressing. In addition to its structuring function, the structure-providing paper also has a protective function, particularly during the pressing step. After pressing the layer or cover structure, the structure-providing paper is removed again and can be reused.

[0057] The transparent paper used in the laminate is also known as cellophane. Cellophane is a transparent paper made from finely ground pulp that is largely fat-dense but not moisture-resistant. Its high transparency gives it a very vivid satin effect.

[0058] It is also possible to use unimpregnated paper on the underside. If only about half of the powdered resin is used for the paper, grinding of the laminate on the back side can be omitted after compacting.

[0059] It is also conceivable to apply additional reaction paper on the underside of the layer structure for stabilizing the laminate. Reaction paper is a high-quality impregnated paper used as a reaction material, for example for single-sided flat coverings and other single-sided coatings.

[0060] In a further preferred embodiment of the method according to the invention, additives, in particular flame retardants, are added to the powdered resin.

[0061] As the flame retardant, for example, acetyl acetal, ammonium polyphosphate, tris(tribromoneopentyl)phosphate can be used. The ratio between the flame retardant and the resin powder is preferably 1.5 to 5.

[0062] In a further variant of the method according to the invention, a layer construction consisting of one side of a kraft paper layer spread with powdered resin, optionally at least one porous material layer, at least one further paper layer, in particular a kraft paper layer, a decorative paper layer and / or a covering paper layer, optionally a structure providing part, optionally a transparent paper and optionally a reaction part is pressed in a hot press, in particular in a continuous press or in a double-belt press.

[0063] The compression step in the press (CPL press) was carried out at 50 kg / cm 2 Up to 70kg / cm 2 The pressing is carried out at a pressure of between 100° C. and a temperature of between 150° C. and 200° C., preferably 180° C. The press speed is 5 m / min to 20 m / min, preferably 5 m / min to 15 m / min, for example 9.5 m / min. The laminate produced in the press has a thickness of between 0.15 mm and 1.2 mm.

[0064] The method of the invention makes it possible to provide a laminate (or covering), in particular a CPL, which each comprises at least one resin-impregnated kraft paper layer as a core layer and further paper layers, in particular kraft paper layers, decorative paper layers and / or covering paper layers.

[0065] In one embodiment, the laminate comprises at least one cover paper layer, at least one decorative paper layer and at least two kraft paper layers. The layer structure from top to bottom can be as follows: cover paper layer, decorative paper layer, first kraft paper layer and second kraft paper layer.

[0066] In another embodiment, the laminate includes at least one cover paper layer, at least one decorative paper layer, at least two kraft paper layers, and at least one transparent paper layer. Optionally, at least one counteracting portion may be provided. The layer structure, from top to bottom, may be as follows: cover paper layer, decorative paper layer, first and second kraft paper layers, and transparent paper (glass paper layer).

[0067] In another embodiment, the laminate includes at least one structure-providing portion, at least one cover paper layer, at least one decorative paper layer, at least two kraft paper layers, and at least one transparent paper layer. Optionally, at least one counteracting portion may be provided. The layer structure, from top to bottom, may be as follows: structure-providing portion, cover paper layer, decorative paper layer, first and second kraft paper layers, and transparent paper (glass paper layer).

[0068] In another variant, a laminate that can be produced using the method according to the invention comprises, if necessary, at least one structure-providing part, at least one covering paper layer, at least one decorative paper layer, at least two kraft paper layers, and at least one transparent paper, wherein at least one flame retardant is provided between the two kraft paper layers.

[0069] In a further embodiment, a laminate that can be produced using the method of the present invention comprises: optionally at least one structural element, at least one cover paper layer, at least one decorative paper layer, at least two kraft paper layers, at least one layer of (porous) covering material, in particular glass fiber mat or aluminum foil, and at least one transparent paper. Optionally, at least one counteracting element may be provided. The layer structure, from top to bottom, may be as follows: optionally a structural element, a cover paper layer, a decorative paper layer, a first kraft paper layer, a layer of covering material, in particular glass fiber mat or aluminum foil, a second kraft paper layer, and a transparent paper (glass paper layer).

[0070] In another embodiment, a laminate that can be produced using the method of the present invention includes: optionally at least one structural component, at least one covering paper layer, at least one kraft paper layer, at least one layer of (porous) covering material, in particular a veneer, and at least one transparent paper. Optionally, at least one counteracting component may be provided. The layer structure, from top to bottom, may be as follows: optionally a structural component, covering paper, a layer of (porous) covering material, in particular a veneer, a kraft paper layer, and a transparent paper (glass paper).

[0071] The counteracting elements mentioned in the above-mentioned embodiments of the laminate are included in each case if necessary.

[0072] The laminate or covering according to the invention has a structure height with a thickness of between 0.1 mm and 3 mm, preferably between 0.1 mm and 1.2 mm. DETAILED DESCRIPTION

[0073] The present invention is explained in detail below with reference to a number of exemplary embodiments.

[0074] For the following examples, the powdered resin BASF 630 (melamine resin) and the preform 82 8583G0 (phenolic resin) were used.

[0075] Example 1:

[0076] 80g / m2 unrolled from rolls at CPL facilities 2 NKP (width: 1340 mm). Approximately 10 g of water / m 2 Spray onto kraft paper (upper side).

[0077] A mixture of phenolic resin and melamine resin is spread onto the NKP immediately before pressing. The ratio of phenolic resin to melamine resin is 3 to 2. The resins are mixed in a mixing unit and then fed to the spreading unit. The application rate is 136 g of resin mixture / m 2 (Resin coating: 85% based on two NKPs).

[0078] The spreading device is set so that the product strip is not covered with resin powder for two centimeters on both sides. A second NKP layer of the same grammage is applied to the kraft paper by unrolling. The decorative impregnation and the covering impregnation are placed on top of it with conventional resinization and conventional humidity.

[0079] The construction together with the structure providing portion on the upper side and the glassine paper (60 g / m 2 ) moves through the facility at a speed of 9.5 m / min. The pressing temperature is 180°C and the pressing pressure is 60 kg / cm 2 No resin flow was observed at the edges after the press. The resulting laminate was trimmed and rolled up.

[0080] This laminate was subsequently tested for several important parameters (water vapor test, post-forming properties, scratch test) in comparison with a laminate produced with impregnated NKP according to DIN EN 438. No differences were found between the two laminates.

[0081] Example 2:

[0082] 80g / m2 unrolled from rolls at CPL facilities 2 , 120g / m 2 and 160g / m 2 NKP (width: 1340 mm) with a grammage of 10 g water / m 2 Up to 20g water / m 2 (80g NKP), 15g water / m 2 Up to 30g water / m 2 (120g NKP) and 20g water / m 2 Up to 40g water / m 2 (160 g NKP) was sprayed onto the upper side.

[0083] A mixture of phenolic resin and melamine resin is spread onto the NKP immediately before pressing. The ratio of phenolic resin to melamine resin is 3 to 2. The resins are mixed in a mixing unit and then fed to the spreading unit. The application rate is 136 g of resin mixture / m 2 (80g / m 2 ), 204g resin mixture / m 2 (120g / m 2 ) and 272g resin mixture / m 2 (160g / m 2 )(Resin coating: 85% based on two NKPs).

[0084] The spreading device is set so that the product strip is not covered with resin powder for two centimeters on both sides. A second NKP layer of the same grammage is applied to the kraft paper by unrolling. The decorative impregnation and the covering impregnation are placed on top of it with conventional resinization and conventional humidity.

[0085] The construction together with the structure providing portion on the upper side and the glassine paper (60 g / m 2 ) moves through the facility at a speed of 9.5 m / min. The pressing temperature is 180°C and the pressing pressure is 60 kg / cm 2 No resin flow was observed at the edges after the press. The resulting laminate was trimmed and rolled up.

[0086] The laminates were then tested according to DIN EN 438 Part 2, "12. Resistance to immersion in boiling water." Delamination due to poor resin distribution / resin penetration is crucial. The results are listed in Table 1. In laminates with resinized NKP produced using a normal impregnation process, neither blistering nor delamination was typically observed during the "storage in boiling water" test.

[0087]

[0088]

[0089] Table 1

[0090] Example 3:

[0091] 80g / m2 unrolled from rolls at CPL facilities 2 , 120g / m 2 and 160g / m 2 (width: 1340mm) of NKP. With the help of the wetting device, about 10g water / m 2 Up to 20g water / m 2 Spray onto kraft paper (upper side).

[0092] A mixture of phenolic resin and melamine resin is spread onto the NKP immediately before pressing. The ratio of phenolic resin to melamine resin is 3 to 2. The resins are mixed in a mixing unit and then fed to the spreading unit. The application rate is 122 g of resin mixture / m 2 (80g / m 2 )、180g(120g / m 2 ) and 245g resin mixture / m 2 (160g / m 2 ) resin mixture / m 2 (Resin coating: 77% based on two NKPs).

[0093] The spreading device is set so that the product strip is not covered with resin powder for two centimeters on both sides. A second NKP layer of the same grammage is applied to the kraft paper by unrolling. The decorative impregnation and the covering impregnation are placed on top of it with conventional resinization and conventional humidity.

[0094] The construction together with the structure providing portion on the upper side and the glassine paper (60 g / m 2 ) moves through the facility at a speed of 9.5 m / min. The pressing temperature is 180°C and the pressing pressure is 60 kg / cm 2 No resin flow was observed at the edges after the press. The resulting laminate was trimmed and rolled up.

[0095] The laminates were then tested according to DIN EN 438 Part 2, "12. Resistance to immersion in boiling water." Delamination due to poor resin distribution / resin penetration is crucial. The results are listed in Table 2. In laminates with resinized NKP produced using a standard impregnation process, neither blistering nor delamination was typically observed during the "storage in boiling water" test.

[0096]

[0097]

[0098] Table 2

[0099] As can be seen from the results, the resin coating can be reduced by 10% without observing a loss in quality. Surprisingly, the mass increase of the impregnated article with less resin coating is lower than that of the laminate with higher resin coating.

[0100] Example 4:

[0101] 165g / m² unrolled from rolls at CPL facilities 2 NKP (width: 1340 mm). With the help of the wetting device, about 20 g of water / m 2 Up to 40g water / m 2 Spray onto kraft paper (upper side).

[0102] A mixture of flame retardant (acetylglutamine), phenolic resin, and melamine resin was spread onto the NKP immediately before pressing. The ratio of glutamine, phenolic resin, and melamine resin was 1.5:3:2. The coating amount was 316 g resin + flame retardant / m 2 (Resin coating: 75% based on two NKPs).

[0103] The spreading device is set so that the outer two centimeters of the product strip are not covered with resin powder. A second NKP layer of the same grammage is applied to the kraft paper by unrolling. The decorative impregnation and the covering impregnation are placed on top, with the usual resinization and usual humidity.

[0104] The construction together with the structure providing portion on the upper side and the glassine paper (60 g / m 2 ) moves through the facility at a speed of 9.5 m / min. The pressing temperature is 180°C and the pressing pressure is 60 kg / cm 2 .

[0105] The resulting laminate was rolled up and then tested according to DIN EN 13 501-1:2018 (Classification of Fire Resistance). The result was c-s1, d0.

[0106] Example 5:

[0107] 80g / m2 unrolled from rolls at CPL facilities 2 NKP (width: 1340 mm). Approximately 10 g of water / m 2 Sprayed onto kraft paper (upper side). Directly before pressing, a mixture of phenolic resin and melamine resin was spread onto the NKP.

[0108] The ratio between phenolic resin and melamine resin is 3 to 2. The resins are mixed in a mixing device and then conveyed to the spreading device. The coating amount is 136g of resin mixture / m 2 (Resin coating: 85% based on two NKPs).

[0109] The spreading device is set so that the product strip is not spread with resin powder on the two outer centimeters on both sides. 2 ) onto kraft paper and also spread 136g / m 2 Resin. A fiberglass mat is used to improve impact resistance. A second NKP layer of the same grammage is applied to the mat by unrolling. The decorative and covering impregnations are then applied with conventional resinization and conventional humidity.

[0110] The construction together with the structure providing portion on the upper side and the glassine paper (60 g / m 2 ) moves through the facility at a speed of 9.5 m / min. The pressing temperature is 180°C and the pressing pressure is 60 kg / cm 2 No resin flow was observed at the edges after the press. The resulting laminate was trimmed and rolled up.

[0111] The laminate was then tested for several important parameters (water vapor test, scratch test) in accordance with DIN EN 438, compared to a laminate produced with impregnated NKP. No differences were observed between the two laminates. The laminated composite was stored in hot water (2 h) to test the composite. No blistering or delamination was observed. The water absorption was 5.5%. When testing the impact strength in accordance with DIN EN 438-TI.20 "Small Ball" (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.

[0112] Example 6:

[0113] 80g / m2 unrolled from rolls at CPL facilities 2 NKP (width: 1340 mm). Approximately 10 g of water / m 2 Sprayed onto kraft paper (upper side). Directly before pressing, a mixture of phenolic resin and melamine resin was spread onto the NKP.

[0114] The ratio between phenolic resin and melamine resin is 3 to 2. The resins are mixed in a mixing device and then conveyed to the spreading device. The coating amount is 68g of resin mixture / m 2 (Resin coating: 85% based on two NKPs).

[0115] The spreading device is set so that the product strip is not spread with resin powder on the outer two centimeters on both sides. 0.2 mm aluminum foil with primer on both sides is unfolded on the kraft paper to reduce water vapor permeability and is also spread with 68 g / m 2 Resin. A second NKP layer of the same grammage is applied to the aluminum foil by unrolling. The decorative impregnation and the covering impregnation are placed on top with conventional resinization and conventional humidity.

[0116] The construction together with the structure providing portion on the upper side and the glassine paper (60 g / m 2 ) moves through the facility at a speed of 9.5 m / min. The pressing temperature is 180°C and the pressing pressure is 60 kg / cm 2 No resin flow was observed at the edges after the press. The resulting laminate was trimmed and rolled up.

[0117] Example 7:

[0118] 80g / m2 unrolled from rolls at CPL facilities 2 NKP (width: 1340 mm). Approximately 10 g of water / m 2 Spray onto kraft paper (upper side).

[0119] A mixture of phenolic resin and melamine resin is spread onto the NKP immediately before pressing. The ratio of phenolic resin to melamine resin is 3 to 2. The resins are mixed in a mixing unit and then fed to the spreading unit.

[0120] The coating amount is 210g resin mixture / m 2 (Resin coating: 85% based on two NKPs). The spreading device was set so that the product strip was not covered with resin powder for two centimeters on both sides. An oak veneer board (thickness: 0.5 mm) measuring 1400 mm x 1340 mm was placed on the kraft paper. The decorative impregnation and covering impregnation were placed on top, having been resinized and moistened to a standard level.

[0121] The construction together with the structure providing portion on the upper side and the glassine paper (60 g / m 2 ) moves through the facility at a speed of 9.5 m / min. The pressing temperature is 180°C and the pressing pressure is 60 kg / cm 2 The resulting laminate showed no delamination and had good transparency.

Claims

1. A method for producing a laminate comprising at least one kraft paper layer, the method comprising the following steps: - providing at least one unprocessed or unimpregnated kraft paper layer, - applying at least one first layer consisting of at least one powdered resin onto at least one side of said kraft paper layer, - placing at least one further paper layer onto the side of the kraft paper layer on which the powdered resin is spread, and - Compacting the layer construction.

2. The method according to claim 1, It is characterized in that The at least one unprocessed kraft paper layer has a 2 and 200g / m 2 Between, preferably between 80g / m 2 and 170g / m 2 between, particularly preferably between 80g / m 2 and 160g / m 2 between 80 g / m 2 and 120g / m 2 The weight between.

3. The method according to any one of the preceding claims, It is characterized in that The at least one unprocessed kraft paper layer is moistened prior to spreading the powdered resin.

4. The method according to claim 3, It is characterized in that For wetting, water was added at 10 g water / m 2 and 40g water / m 2 For example, between 10g water / m 2 Up to 20g water / m 2 Between 15g water / m 2 Up to 30g water / m 2 Between and / or at 20g water / m 2 Up to 40g water / m 2 An amount between 1% and 2% is applied to the unprocessed kraft paper layer.

5. The method according to any one of the preceding claims, It is 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. The method according to any one of the preceding claims, It is characterized in that The powdered resin was mixed at 50 g / m 2 Up to 350g / m 2 , 100g / m 2 Up to 300g / m 2 , preferably 120g / m 2 Up to 280g / m 2 , particularly preferably 150g / m 2 Up to 250g / m 2 An amount of the adhesive is applied to the at least one kraft paper layer.

7. The method according to any one of the preceding claims, It is characterized in that The at least one further paper layer to be deposited is a kraft paper layer, a decorative paper layer or an overlay paper layer, preferably an unprocessed kraft paper layer.

8. The method according to any one of the preceding claims, It is characterized in that On the side of the raw kraft paper layer interspersed with the powdered resin is first placed the at least one layer of coating material and then the at least one further paper layer.

9. The method according to claim 8, It is characterized in that Overlays, graphite-containing papers, plastic films, aluminum foils, felt materials and other textile materials are used as covering material layers.

10. The method according to any one of the preceding claims, It is characterized in that The layer construction consisting of an unprocessed kraft paper layer and at least one further paper layer is compacted with at least one structure-providing paper (placed on the at least one further paper layer on the upper side of the layer stack) and at least one transparent paper (on the lower side of the layer stack).

11. The method according to any one of the preceding claims, It is characterized in that Additives, particularly flame retardants, are added to the powdered resin.

12. The method according to any one of the preceding claims, It is characterized in that The layer construction consisting of one side of the unprocessed kraft paper layer spread with the powdered resin, optionally at least one layer of covering material, at least one further paper layer, in particular a kraft paper layer, a decorative paper layer and / or a cover paper layer, optionally a structure providing part, optionally a transparent paper and optionally a reaction part is pressed in a hot press, in particular a continuous press or a double-belt press.

13. A laminate producible by the method according to any one of the preceding claims, comprising at least one decorative paper layer, at least two kraft paper layers and at least one transparent paper, wherein at least one flame retardant is arranged between two of the kraft paper layers.

14. A laminate which can be produced using the method according to any of the preceding claims, comprising at least one cover paper layer, at least one decorative paper layer, at least two kraft paper layers, at least one layer of a covering material, in particular a glass fiber mat, and at least one transparent paper.

15. A laminate producible in a method according to any one of the preceding claims, comprising at least one covering paper layer, at least one kraft paper layer, at least one layer of a covering material, in particular a veneer, and at least one transparent paper.

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