Sandwich panel, and method and device for producing a sandwich panel

Abstract

The invention relates to a method for producing a sandwich panel (10), in particular for buildings and / or freight transport, in which: - a first cover layer (11) of the sandwich panel (10) is fed to at least one adhesive-application device (101) for large-area application of adhesive, wherein the first cover layer (11) has a profile edge (12), which extends in the feed direction (ZR) and has at least one undercut (13); - a non-reactive adhesive (14) is applied by the adhesive-application device (101) onto an in particular large-area inner face (15) of the first cover layer (11); and - the non-reactive adhesive (14) is applied through at least one laterally projecting nozzle (102) onto at least one undercut face (16), adjoining the inner face (15) of the first cover layer (11), of the profile edge, wherein the nozzle (102) protrudes at least in part into the undercut; - at least one self-expanding plastic material (17), in particular a foaming compound, is dispensed onto the applied non-reactive adhesive (14); - a second cover layer (18) of the sandwich panel (10) is guided so as to be spaced apart from and opposite the first cover layer (11) such that, by expanding the dispensed plastic material (17), the two cover layers (11, 18) are interconnected to form the sandwich panel (10).

Description

[0001] SANDWICH PANEL AND METHOD AND DEVICE FOR MANUFACTURING

[0002] A SAN DWICH PANEL

[0003] Description

[0004] The invention relates to a method and a device for producing a sandwich panel and to a sandwich panel.

[0005] Sandwich panels consisting of two opposing cover layers, often made of metal, and a foam core in between are manufactured in a variety of ways. During production, for example, an adhesive is applied to one of the two cover layers, followed by a self-foaming compound to form a rigid foam core that bonds the two opposing cover layers together. The adhesive can be a reactive adhesive, such as a two-component polyurethane adhesive or a hot melt adhesive.

[0006] The outer layer that is additionally bonded to the foam core is preferably used as the outer side of the sandwich panel. When used as a building facade, as cladding for vehicle bodies, or similar applications, this external arrangement is advantageous, as environmental influences such as solar radiation, rain, hail, etc. require a reinforced bond between the panel layers in this section. Therefore, there is an increased risk of blistering on the outer side of the sandwich panel due to the outer layer detaching from the foam core in sections. This can occur particularly due to thermal shock, resulting, for example, from strong temperature fluctuations at the outer layer.

[0007] The problem of unwanted blistering particularly affects the joints of the panels through which two adjacent sandwich panels can be connected to each other.

[0008] The invention is therefore based on the object of providing a method for producing a sandwich panel in which the risk of blistering is reduced, particularly in the area of ​​a profile edge for connecting two sandwich panels. The invention is further based on the object of providing a device for producing a sandwich panel and a sandwich panel.

[0009] According to the invention, this object is achieved with regard to the manufacturing method by the subject matter of claim 1. With regard to the device and the sandwich panel, the above-mentioned object is achieved by the subject matter of claim 10 (device) and claim 15 (sandwich panel).

[0010] Specifically, the problem is solved by a method for producing a sandwich panel, in particular for buildings and / or goods transport, in which

[0011] - a first cover layer of the sandwich panel is fed to at least one adhesive application device for large-area adhesive application, wherein the first cover layer has a profile edge running in the feed direction with at least one undercut;

[0012] - a non-reactive adhesive is applied by the adhesive application device to a, in particular large-area, inner surface of the first cover layer; and

[0013] - the non-reactive adhesive is applied through at least one laterally projecting nozzle onto at least one undercut surface of the profile edge adjacent to the inner surface of the first cover layer, wherein the nozzle protrudes at least partially into the undercut;

[0014] - at least one self-expanding plastic material, in particular a foaming mass, is applied to the applied non-reactive adhesive;

[0015] - a second cover layer of the sandwich panel is guided opposite the first cover layer at a distance such that by expanding the applied plastic material the two cover layers are joined together to form the sandwich panel.

[0016] The method according to the invention has the significant advantage that the non-reactive adhesive is not only applied to the large inner surface of the first cover layer, but is also introduced into the undercut of the profile edge of the first cover layer. As a result, the area of ​​the undercut adjacent to the inner surface, namely the undercut surface, is coated with the non-reactive adhesive. This has the significant advantage that the subsequently applied self-expanding plastic material, in its expanded state, forms a highly strong bond with the first cover layer, not only in the area of ​​the large inner surface, but also in the area of ​​the undercut of the profile edge adjacent to the inner surface. In the context of the invention described here, the adhesive therefore acts as a "primer," which promotes adhesion between the profile surface and an applied foam.

[0017] The sandwich panel produced in this way thus exhibits increased resistance to environmental influences such as solar radiation, rain, hail, etc. In particular, tests have shown that the risk of blistering caused by partial detachment of the undercut surface or the inner surface of the first cover layer from the expanded plastic material is significantly reduced with the sandwich panel produced according to the invention. Such a sandwich panel is particularly resistant to thermal shocks, which can occur, for example, due to strong temperature fluctuations on the cover layer.

[0018] The use of a non-reactive adhesive is particularly advantageous, as its improved flow properties allow application via a nozzle or nozzle protruding from the side. In contrast, reactive adhesives have the disadvantage that their viscosity prevents nozzle application, as the nozzle opening(s) would become clogged. To counteract this, a centrifugal spraying process would have to be used, for example, which leads to increased air / moisture ingress and thus promotes detachment of an expanded foam core. The process according to the invention prevents this effect.

[0019] In use, the first cover layer is preferably used as the outer side of the sandwich panel. Specifically, the first cover layer has an outer surface, in particular a visible surface, that is at least opposite the inner surface. The outer surface advantageously corresponds to the outer side of the sandwich panel. For example, the sandwich panel is used to form an outer facade of a building and / or to form walls, roofs, floors or doors of superstructures, in particular vehicle bodies, for the transport of goods. Other applications are possible. The first cover layer is used as the outer side, for example to withstand the environmental influences described, without the inner surface or the undercut surface becoming detached from the expanded plastic material.

[0020] The self-expanding plastic material is preferably a foamable or self-foaming mass. In the expanded state, the plastic material preferably forms a foam core of the sandwich panel, which is bonded, on the one hand, to the first cover layer and its profile edge by the non-reactive adhesive, and, on the other hand, is bonded, in particular directly, to the second, opposite cover layer.

[0021] The profile edge of the first cover layer preferably runs parallel to the feed direction. The first cover layer preferably has a profile edge on both long sides, which can be identical or different. The undercut of the profile edge is preferably open towards the inner surface of the first cover layer. In other words, the undercut is open inwards, i.e. towards the center of the first cover layer. Or in other words, the undercut is open inwards transversely to the feed direction. The undercut surface borders on the inner surface. In other words, the undercut surface merges into the inner surface of the first cover layer, in particular essentially without offset.

[0022] The profile edge serves to form a connection point of the sandwich panel, namely to connect two sandwich panels produced according to the invention to each other, preferably in a form-fitting manner. Two adjacent sandwich panels are joined together via their connection points. The profile edge is preferably designed so that, when two sandwich panels are connected, only a shadow gap is visible from the outside. These are therefore also referred to as hidden joints.

[0023] Advantageous embodiments of the invention are specified in the dependent claims. In a preferred embodiment, the non-reactive adhesive is applied to the undercut surface before and / or after the adhesive application device in the feed direction. In other words, the non-reactive adhesive can be applied first to the undercut surface and then to the large-area inner surface of the first cover layer, or first to the large-area inner surface and then to the undercut surface of the profile edge. For this purpose, the laterally projecting nozzle can be arranged with respect to the adhesive application device such that it is positioned before or after the adhesive application device in the feed direction.

[0024] In the context of the application, "large-area" means that the inner surface is larger than the undercut area. Specifically, the undercut area can be a flat strip that runs in the longitudinal direction of the profile edge. Adjacent to this is the inner surface of the first cover layer, which is larger than the flat strip.

[0025] In a further preferred embodiment, the adhesive application device is stationary when the non-reactive adhesive is being applied to the inner surface of the first cover layer. Additionally or alternatively, the laterally protruding nozzle is stationary when the non-reactive adhesive is being applied to the undercut surface of the profile edge, with the first cover layer running in the feed direction. In this embodiment, it is advantageous that only the two cover layers are moved in the feed direction. The first cover layer preferably runs past below the adhesive application device and / or the laterally protruding nozzle in the feed direction, with the non-reactive adhesive being applied to the inner surface or undercut surface, preferably by means of gravity. This reduces the complexity of the manufacturing device and thus costs. In addition, it facilitates a uniform application of the adhesive.

[0026] Preferably, the non-reactive adhesive is applied to the inner surface of the first cover layer and / or to the undercut surface of the profile edge in a multi-line and / or bead-like pattern. It is particularly advantageous if the non-reactive adhesive is applied to the inner surface and / or the undercut surface in adjacent beads. The beads can be arranged at equal intervals. In other words, the non-reactive adhesive can be applied to the inner surface and / or the undercut surface in a thread-like pattern. This creates a particularly good and strong bond, as the contact between the adhesive and the expanded plastic material, in particular the foam core, is as even and flat as possible. This results in an enlarged adhesive surface.

[0027] The profile edge preferably comprises at least one narrow region adjacent to the undercut surface, which is at least partially filled with the non-reactive adhesive by the laterally projecting nozzle and / or another nozzle. The non-reactive adhesive introduced into the narrow region is preferably foamed or is foamable, in particular self-foamable. Particularly preferably, the non-reactive adhesive applied to the undercut surface and the non-reactive adhesive filled into the narrow region are the same. The narrow region can be a profile nose of the profile edge running in the longitudinal direction of the first cover layer and open to the undercut surface.

[0028] It is advantageous if the narrow area is filled with a foamable adhesive, in particular the foamed non-reactive adhesive, independently of the application of the self-expanding plastic material to form a panel core layer. This can be done before or after the application of the non-reactive adhesive to the undercut surface. For this purpose, a separate nozzle can be provided, which serves, in particular, exclusively to fill the narrow area. This has the advantage of ensuring a precise separation between filling and adhesive application, thus preventing undesirable mixing of the material introduced into the narrow area and the applied non-reactive adhesive.

[0029] Alternatively, the narrow area can be filled using the nozzle protruding from the side. Advantageously, as with the two-nozzle combination described above, the filling of the narrow area and the application of the non-reactive adhesive to the undercut surface are performed at separate times.

[0030] It is possible to insert a prefabricated seal into the narrow area.

[0031] This can preferably be done alternatively or in addition to the application of the foamed adhesive. The seal is preferably inserted into the narrow area using at least one press-in wheel. Other seal insertion devices are possible.

[0032] The adhesive application device and the laterally protruding nozzle can use different adhesive supplies (so that the adhesive applied over a large area can be different from the adhesive introduced into the undercut), or the same adhesive supply can be used. Preferably, the adhesive application device and the laterally protruding nozzle use one and the same adhesive supply. For example, the adhesive application device and the laterally protruding nozzle can be connected to the same pump and the same adhesive tank. It is advantageous if the adhesive application device and the laterally protruding nozzle are also controlled by the same controller. In this embodiment, it is advantageous that the laterally protruding nozzle is integrated into an existing supply system, thus saving costs.

[0033] It is particularly advantageous if only non-reactive adhesive is applied to the inner surface of the first cover layer and / or to the undercut surface of the profile edge. This is the same non-reactive adhesive. This eliminates the need for a reactive adhesive, which, due to its flow properties, requires complex application.

[0034] Preferably, at least one hot melt adhesive is used as the non-reactive adhesive, which is applied in particular using the hot melt process. The hot melt adhesive preferably comprises: a. as the first component, at least one styrene block copolymer SC, in particular with a proportion of at least 5 wt. %, preferably at least 15 wt. %, and more preferably at least 20 wt. %; b. as the second component, at least one tackifying hydrocarbon resin TR, in particular with a proportion of 15-55 wt. %, preferably 20-50 wt. %; c. at least one plasticizer PL, selected from process oils and liquid hydrocarbon resins.

[0035] The weight specifications refer to the total weight of the hot melt adhesive. In other words, the non-reactive adhesive is applied to the inner surface of the first cover layer and / or the undercut surface of the profile edge using the hot melt process (commonly known).

[0036] Tests have shown that a first cover layer made of aluminum and an adhesive with this composition creates a particularly high-strength bond. During the tests, a first sample sandwich panel was produced without any adhesive applied to the undercut surface. The first cover layer made of aluminum was then torn away from the expanded core layer. It turned out that the core layer separated from the inner aluminum surface (adhesive fracture). For comparison purposes, a second sample sandwich panel was also produced with adhesive applied to the undercut surface, and the first cover layer was torn away from the core layer in the same way as in the first sample sandwich panel. This advantageously resulted in a cohesive fracture pattern.

[0037] According to the aforementioned embodiment, the hot melt adhesive comprises at least one styrene block copolymer SC as its first component. The first component of the styrene block copolymer SC can, for example, make up 5-45 wt.%, preferably 15-45 wt.%, more preferably 20-40 wt.%, of the total weight of the hot melt adhesive. Suitable styrene block copolymers are, in particular, block copolymers containing polystyrene and polybutadiene blocks and / or polyisoprene blocks. Such styrene block copolymers can have a linear, radial, or star-shaped structure, with the linear structure being particularly preferred.

[0038] According to one embodiment, the at least one styrene block copolymer SC comprises at least one styrene-isoprene diblock (SI) and / or triblock copolymer (SIS) and / or at least one styrene-butadiene diblock (SB) and / or triblock copolymer (SBS).

[0039] As described above, the hot melt adhesive preferably comprises as a second component at least one tackifying resin TR.

[0040] The term "tackifying resin" in the context of this application refers to resins that generally improve the adhesion and / or stickiness of an adhesive composition. The term "tackiness" in the context of this application refers to the property of a substance to be sticky or adhesive upon simple contact. Tackiness can be measured, for example, as loop adhesion. Preferred tackifying resins are tacky at a temperature of 25°C. Examples of suitable tackifying resins are natural resins, synthetic resins, and chemically modified natural resins.

[0041] Examples of natural resins and chemically modified natural resins include rosin, rosin esters, phenolically modified rosin esters, and terpene resins. The term "rosin" includes gum rosin, wood rosin, tall oil rosin, distilled rosin, and modified rosin resins, such as dimerized, hydrogenated, maleated, and / or polymerized versions of these resins.

[0042] Suitable terpene resins include copolymers and terpolymers of natural terpenes, such as styrene / terpene and alpha-methylstyrene / terpene resins; polyterpene resins, which generally result from the polymerization of terpene hydrocarbons, such as the bicyclic monoterpene known as pinene, in the presence of Friedel-Crafts catalysts at moderately low temperatures; hydrogenated polyterpene resins; and phenolically modified terpene resins, including hydrogenated derivatives thereof.

[0043] The term "synthetic resin" refers to compounds obtained by controlled chemical reactions such as polyaddition or polycondensation between well-defined reactants that do not themselves exhibit the properties of resins.

[0044] The monomers that can be polymerized to synthesize the synthetic resins include aliphatic monomers, cycloaliphatic monomers, aromatic monomers, or mixtures thereof. Aliphatic monomers can include C4, C5, and C6 paraffins, olefins, and conjugated diolefins. Examples of aliphatic monomers or cycloaliphatic monomers are butadiene, isobutylene, 1,3-pentadiene, 1,4-pentadiene, cyclopentane, 1-pentene, 2-pentene, 2-methyl-1-pentene, 2-methyl-2-butene, 2-methyl-2-pentene, isoprene, cyclohexane, 1-3-hexadiene, 1-4-hexadiene, cyclopentadiene, dicyclopentadiene, and terpenes. Aromatic monomers can include C8, C9, and C10 aromatic monomers. Examples of aromatic monomers are styrene, indene, styrene derivatives, indene derivatives, coumarone, and combinations thereof.Particularly suitable resins include resins produced by polymerizing mixtures of unsaturated monomers obtained as byproducts from the cracking of natural gas liquids, gas oil, or petroleum naphthenes. Such resins, derived from petroleum-based feedstocks, are also referred to as "petroleum resins" or "hydrocarbon resins." These include purely monomeric aromatic resins produced by polymerizing aromatic monomer feedstocks that have been purified to remove color-causing impurities and tightly control the product composition. Tackifying hydrocarbon resins typically have a relatively low average molecular weight (Mw). n ), e.g. in the range of 250 - 5000 g / mol, and a glass transition temperature above 0 °C, preferably equal to or higher than 15 °C, more preferably equal to or higher than 30 °C.

[0045] Examples of hydrocarbon resins for use as tackifying resin TR include aliphatic C5 hydrocarbon resins, mixed aliphatic / aromatic C5 / C9 hydrocarbon resins, aromatically modified aliphatic C5 hydrocarbon resins, cycloaliphatic hydrocarbon resins, mixed aliphatic / cycloaliphatic C5 hydrocarbon resins, mixed C9 aromatic / cycloaliphatic hydrocarbon resins, mixed C5 aliphatic / cycloaliphatic / C9 aromatic hydrocarbon resins, aromatically modified cycloaliphatic hydrocarbon resins, C9 aromatic hydrocarbon resins, polyterpene resins and copolymers and terpolymers of natural terpenes as well as hydrogenated versions of the aforementioned hydrocarbon resins. The designations "C5" and "C9" mean that the monomers from which the resins are made are predominantly hydrocarbons with 4-6 and 8-10 carbon atoms, respectively.The term "hydrogenated" encompasses fully, substantially, and at least partially hydrogenated resins. Partially hydrogenated resins can, for example, have a degree of hydrogenation of 50%, 70%, or 90%.

[0046] Preferably, the at least one tackifying resin TR is a non-functionalized tackifying resin. The term "non-functionalized tackifying resin" means tackifying resins that are not chemically modified to contain functional groups such as epoxy, silane, sulfonate, amide, or anhydride groups. The at least one tackifying resin TR of the hot melt adhesive preferably comprises: a softening point, measured by the ring and ball method according to DIN EN 1238:2011, in the range of 65-175°C, preferably 70-145°C, particularly preferably 75-115°C, even more preferably 80-125°C; and / or an average molecular weight (M n) in the range of 150 - 5000 g / mol, preferably 250 - 3500 g / mol, particularly preferably 250 - 3000 g / mol, even more preferably 250 - 2500 g / mol; and / or a glass transition temperature (T g ), determined by dynamic mechanical analysis (DMA) as the peak of the measured loss modulus (G") curve using an applied frequency of 1 Hz and a strain level of 0.1% at or above 0 °C, preferably at or above 10 °C, more preferably at or above 15 °C, even more preferably at or above 20 °C.

[0047] In addition, the hot melt adhesive preferably comprises at least one plasticizer PL selected from process oils and liquid hydrocarbon resins, with polyolefin resins being preferred as hydrocarbon resin plasticizers. Preferably, the at least one hydrocarbon resin of the plasticizer PL differs from that of the second component of the hot melt adhesive in that they have a different chemical composition, or that they differ at least in their average molecular weight (Mn, usually determined by GPC using suitable standards).For example, it is possible for the tackifying hydrocarbon resin and the hydrocarbon resin used as a plasticizer to be based on C5 hydrocarbons, with the plasticizer in this case having a lower molecular weight (thus providing a plasticizing effect), while the tackifying resin has a higher molecular weight and thus primarily acts in this function. In a composition, such combinations can be distinguished from a composition with only a single C5 resin component by the fact that the molecular weight distribution exhibits two maxima.

[0048] The term "mineral oil" in the context of the application refers to liquid

[0049] Hydrocarbons of lubricating viscosity (i.e., a kinematic viscosity at 100°C of 1 cSt or greater) derived from petroleum and subjected to one or more refining and / or hydroprocessing steps, such as fractionation, hydrocracking, dewaxing, isomerization, and hydrofinishing, to purify and chemically modify the components to achieve a range of final properties. In other words, the term "mineral" in the context of this application refers to refined mineral oils, which may also be referred to as Groups I-III base oils according to the American Petroleum Institute (API) classification.

[0050] Mineral oils used as the at least one plasticizer PL in the hot melt adhesive are preferably paraffinic, naphthenic, and aromatic mineral oils. It is particularly advantageous if the mineral oils are paraffinic and naphthenic oils that contain relatively small amounts of aromatic components, for example, no more than 25 wt.%, preferably no more than 15 wt.%, based on the total weight of the mineral oil.

[0051] The term "synthetic oil" in this application refers to fully synthetic (polyalphaolefin) oils, which are also referred to as Group IV base oils according to the American Petroleum Institute (API) classification. Suitable synthetic oils are produced from liquid polyalphaolefins (PAOs), which are obtained by polymerizing α-olefins in the presence of a polymerization catalyst, such as a Friedel-Crafts catalyst. Liquid PAOs are generally high-purity hydrocarbons with a paraffinic structure and a high degree of side-chain branching. Synthetic oils obtained from so-called gas-to-liquids processes are particularly suitable.

[0052] In the context of the application, the term "liquid polyolefin resin" refers to a polyolefin resin that flows at normal room temperature, i.e. has a pour point of less than 20 °C.

[0053] Suitable liquid polyolefin resins that can be used as at least one plasticizer PL for the hot melt adhesive include, for example, liquid polybutene and liquid polyisobutylene (PIB). The term "liquid polybutene" in the present disclosure refers to low-molecular-weight olefin oligomers containing isobutylene and / or 1-butene and / or 2-butene. The ratio of the C4-olefin isomers can vary depending on the manufacturer and quality. If the C4-olefin is exclusively 1-butene, the material is referred to as "poly-n-butene" or "PN B." The term "liquid polyisobutylene" in the present document refers to low-molecular-weight olefin oligomers of isobutylene, which preferably contain at least 75 wt. %, preferably at least 85 wt. %, of repeat units derived from isobutylene.Suitable liquid polybutenes and polyisobutylenes have a number average molecular weight (Mn) of less than 5000 g / mol, preferably less than 3500 g / mol, more preferably less than 3000 g / mol, even more preferably less than 2500 g / mol.

[0054] Particularly advantageous is the use of the following liquid polybutenes and liquid polyisobutylenes, comprising: an average molecular weight (M n ) of 150 - 3500 g / mol, preferably 250 - 3000 g / mol, particularly preferably 350 - 2500 g / mol; and / or a pour point, determined according to ISO 3016, in the range from -10 to +15 °C, preferably from -10 to +10 °C; and / or a polydispersity index (M w / M n ), determined by GPC, of ​​at most 5, preferably in the range of 0.5 - 5.0, more preferably 1.0 - 4.5, even more preferably 1.0 - 3.5.

[0055] The at least one plasticizer PL is preferably 0.5 - 15 wt.%, preferably 1.5 - 12.5 wt.%, particularly preferably 2.5 - 10 wt.% of the total weight of the mass of the hot melt adhesive.

[0056] Thermoplastic resins TP preferably used in the hot melt adhesive may comprise: a softening point, measured by the ring and ball method according to the standard DIN EN 1238:2011, in the range of 125 - 250 °C, preferably 130 - 225 °C, more preferably 135 - 200 °C, even more preferably 140 - 185 °C; and / or an average molecular weight (M n ) in the range of 150 - 5000 g / mol, preferably 500 - 4500 g / mol, more preferably 1000 - 3500 g / mol, even more preferably 1500 - 3500 g / mol and / or a glass transition temperature (T g), which is determined by dynamic mechanical analysis (DMA) as the peak value of the measured loss modulus curve (G") using an applied frequency of 1 Hz and a strain level of 0.1%, at or above 35 °C, preferably at or above 50 °C, more preferably at or above 65 °C, even more preferably at or above 75 °C.

[0057] In addition, the hot melt adhesive may contain other auxiliaries and additives, for example, those from the group of UV absorbers, UV and heat stabilizers, optical brighteners, antioxidants, pigments, dyes, and drying agents. Examples of UV stabilizers that may be present in the hot melt adhesive composition include sterically hindered phenols. The total amount of these additional auxiliaries and additives is preferably a maximum of 15 wt.%, preferably a maximum of 10 wt.%, and particularly preferably a maximum of 5 wt.% of the total weight of the hot melt adhesive.

[0058] The prefix "poly" in substance names such as "polyol" or "polyisocyanate" preferably refers to substances that formally contain two or more of the functional groups mentioned in their name per molecule. For example, a polyol is a compound with two or more hydroxyl groups, while a polyisocyanate is a compound with two or more isocyanate groups.

[0059] The term "polymer" essentially refers to a collection of chemically uniform macromolecules produced by a polyreaction (polymerization, polyaddition, polycondensation), where the macromolecules differ in their degree of polymerization, molecular weight, and chain length. The term "polymer" also includes derivatives of this collection of macromolecules resulting from polyreactions, i.e., compounds obtained by reactions such as additions or substitutions of functional groups in predetermined macromolecules, which may be chemically uniform or chemically heterogeneous.

[0060] The term "molecular weight" refers to the molar mass (g / mol) of a molecule or part of a molecule, also called a "part." The term "average molecular weight" refers to the number average molecular weight (M n) or the weight average molecular weight (M w ) an oligomeric or polymeric mixture of molecules or moieties. The molecular weight can be determined by conventional methods, preferably by gel permeation chromatography (GPC) using polystyrene as the standard, styrene-divinylbenzene gel with a porosity of 100 angstroms, 1000 angstroms, and 10,000 angstroms as the column, and, depending on the molecule, tetrahydrofuran as the solvent at 35°C or 1,2,4-trichlorobenzene as the solvent at 160°C.

[0061] The term "softening point" or "softening temperature" refers to the temperature at which the compound softens to a rubbery state, or to the temperature at which the crystalline portion within the compound melts. The softening point can be measured using the ring and ball method according to DIN EN 1238:2011.

[0062] The term "glass transition temperature" (T g) refers to the temperature above which a polymer component becomes soft and pliable and below which it becomes hard and glassy. The glass transition temperature (Tg) is preferably determined by dynamic mechanical analysis (DMA) as the peak value of the measured loss modulus curve (G") at an applied frequency of 1 Hz and a strain level of 0.1%.

[0063] According to a secondary aspect, the invention relates to a device for producing a sandwich panel, in particular for buildings and / or goods transport, the device comprising the following:

[0064] - at least one first feeding and transporting device which runs in a longitudinal direction of the device and is adapted to feed and transport a first cover layer of the sandwich panel;

[0065] - at least one adhesive application device for large-area adhesive application, which is adapted to apply a non-reactive adhesive, in particular hot-melt adhesive, to the inner surface of the first cover layer of the sandwich panel, wherein the feeding and transport device is arranged below the adhesive application device in

[0066] The direction of travel runs longitudinally;

[0067] - at least one laterally projecting nozzle, which is oriented substantially transversely to the longitudinal direction of the device and is adapted to apply the non-reactive adhesive to at least one undercut surface of a profile edge of the first cover layer adjacent to the inner surface of the first cover layer; - at least one downstream device for applying a self-expanding plastic material, in particular a foaming mass;

[0068] - at least one second feeding and transport device which is adapted to feed a second cover layer of the sandwich panel at a distance from the first cover layer in such a way that the two cover layers are bonded together to form the sandwich panel by expanding the applied plastic material.

[0069] The advantages mentioned in connection with the method also apply correspondingly to the device according to the invention. The method steps described in connection with the method are also disclosed in connection with the device, specifically in such a way that the device is configured or adapted to perform these method steps. In general, the device is therefore suitable for carrying out the method according to the invention.

[0070] In a preferred embodiment of the device according to the invention, the at least one laterally projecting nozzle projects laterally transversely to the feed direction beyond the adhesive application device. This makes it possible for the adhesive application device to be arranged within the profile edge, and for the laterally projecting nozzle to engage the undercut. This prevents back-and-forth movement.

[0071] It is possible to provide at least two laterally projecting nozzles that protrude laterally, i.e., on both sides, beyond the adhesive application device transversely to the feed direction. The laterally projecting nozzle is preferably elongated. Preferably, the laterally projecting nozzle is flat in order to engage the undercut.

[0072] In a further preferred embodiment of the device according to the invention, the laterally projecting nozzle comprises at least one front-side nozzle opening for filling a narrow area of ​​the profile edge adjacent to the undercut surface. Additionally or alternatively, the laterally projecting nozzle preferably comprises at least one underside nozzle opening, in particular several such nozzle openings, for applying the non-reactive adhesive to the undercut surface in a multi-line pattern. The nozzle can thus advantageously perform multiple tasks, saving time and costs.

[0073] At least one further nozzle can be arranged upstream of the laterally projecting nozzle, which is adapted to fill a narrow area of ​​the profile edge adjacent to the undercut surface with a foamable adhesive and / or the non-reactive adhesive, at least in sections.

[0074] The adhesive application device and / or the device for applying a self-expanding plastic material preferably extend transversely to the longitudinal direction of the device, in particular across the entire width of the inner surface of the first cover layer. The first cover layer is preferably a web, in particular an aluminum web, wherein, during operation, the adhesive application device or the device for applying the expandable plastic material extend across the width of the web. This enables the application of the non-reactive adhesive and the expandable plastic material to form the core layer across the entire width of the inner surface of the first cover layer.

[0075] According to a further subordinate aspect, the invention relates to a sandwich panel for a building and / or the transport of goods, having a first and a second cover layer which are arranged opposite one another at a distance from one another and delimit an intermediate space which is filled by a foam core, wherein at least one non-reactive adhesive, in particular hot-melt adhesive, is applied to an inner surface of the first cover layer and to an undercut surface of a profile edge of the first cover layer which is adjacent to the inner surface, said adhesive bonding the foam core to the first cover layer.

[0076] The two cover layers are preferably made of metal, in particular coated and uncoated metallic and non-metallic materials. A preferred metallic active ingredient is aluminum. The sandwich panel is preferably produced by a method according to the invention and / or with a device according to the invention.

[0077] The invention is explained in more detail below with reference to the accompanying drawings. The illustrated embodiments represent an example of how the device according to the invention or the sandwich panel according to the invention can be designed. Furthermore, the method according to the invention for producing a sandwich panel is described with reference to the accompanying drawings.

[0078] In these show,

[0079] Fig. 1 is a schematic representation of an apparatus for producing a sandwich panel according to an embodiment of the invention;

[0080] Fig. 2 shows a schematic structure of the device according to Fig. 1;

[0081] Fig. 3 shows a cross section through a sandwich panel according to an embodiment of the invention, in the region of a profile edge of the sandwich panel;

[0082] Fig. 4 a section of a cross-section of the sandwich panel according to Fig. 3 with an exemplary filled narrow area of ​​the profile edge;

[0083] Fig. 5 is a plan view of an application pattern of the non-reactive adhesive as provided on the undercut surface of the profile edge; and

[0084] Fig. 6 shows an adhesive application device of the device according to Fig. 1 for large-area adhesive application to a first cover layer of the sandwich panel.

[0085] In the following description, the same reference numbers are used for identical and equivalent parts.

[0086] Fig. 1 shows schematically an apparatus 100 for producing a

[0087] Sandwich panel 10 according to an embodiment of the invention.

[0088] The sandwich panel 10 to be produced comprises a first cover layer 11, a second cover layer 18 opposite the first cover layer 11 and a core layer 17 formed between the two cover layers 11, 18. This can be clearly seen, for example, in Fig. 3.

[0089] In the present embodiment, the two cover layers 11, 18 are made of metal, more specifically aluminum. Other materials, such as plastic, are possible. The cover layers 11, 18 are formed from sheet metal, as can be seen in Fig. 3. The cover layers 11, 18 are bent in their edge regions, so that they have integrally formed profile edges 12, 22.

[0090] Furthermore, the sandwich panel 10 has a longitudinally extending connection point 21 at which the profile edges 12, 22 of the first and second cover layers 11, 18 are formed. The two profile edges 12, 22 differ in their shape. The profile edge 12 of the first cover layer 11 comprises an undercut 13 with an undercut surface 16 that borders an inner surface 15 of the first cover layer 11. The inner surface 15 is larger than the undercut surface 16. The undercut surface 16 merges directly into the inner surface 15 of the first cover layer 11. The undercut 13 is therefore open towards the inner surface 15. In other words, the undercut 13 is open towards the center of the first cover layer 11. The undercut 13 forms a slot running along the first cover layer 11.

[0091] As shown in Fig. 3, the undercut 13 opens into a narrow region 19 of the profile edge 12. The narrow region 19 is a shallow channel that is open to the undercut 13 on one side and closed on the side opposite the undercut 13 on the other. The shallow channel runs parallel to the undercut 13 along the first cover layer 11. The narrow region 19 has a thickness that is smaller than the thickness of the undercut 13. Specifically, the undercut 13 tapers towards the narrow region 19.

[0092] The sandwich panel 10 is preferably used on buildings, for example to form a facade, or in thermally insulated structures, in particular vehicle bodies, to form walls, ceilings, floors or doors.

[0093] In order to achieve a particularly strong bond between the core layer 17 and the first cover layer 11, the first cover layer 11 is additionally glued to the core layer 17. This has the advantage that the first cover layer 11 adheres particularly well to the core layer 17, preventing detachment of the cover layer 11. The risk of blistering is thus reduced. The first cover layer 11 is preferably arranged facing the outside environment in the installed state, so that the sandwich panel 10 has increased resistance to external environmental influences, such as solar radiation, rain, etc. In particular, the sandwich panel is therefore more resistant to thermal shocks resulting from strong temperature fluctuations.

[0094] The device 100 according to Fig. 1 comprises a first feed and transport device 104, which runs in a longitudinal direction LR of the device 100. The first feed and transport device 104 is adapted to move the first cover layer 11 of the sandwich panel 10. In Fig. 1, it can be seen that the feed and transport device 104 forms a roller conveyor that moves the first cover layer 11 in the longitudinal direction LR of the device 100. Another configuration of the feed and transport device 104 is possible. The longitudinal direction LR corresponds to a feed direction ZR of the feed and transport device 104.

[0095] Furthermore, Fig. 1 shows that the device 100 comprises an adhesive application device 101 for large-area adhesive application. The adhesive application device 101 is adapted to apply a non-reactive adhesive 14 to the inner surface 15 of the first cover layer 11 of the sandwich panel 10, with the feed and transport device 104 extending below the adhesive application device 101 in the longitudinal direction LR of the device 100. The adhesive application device 101 spans the entire width B of the inner surface 15 of the first cover layer 11.

[0096] The adhesive application device 101 has, as shown in Fig. 6, a plurality of openings through which the non-reactive adhesive 14 is applied in thread-like fashion to the inner surface 15 of the first cover layer 11. The non-reactive adhesive 14 is preferably applied to the inner surface 15 of the first cover layer 11 in bead-like fashion. However, it is essential that the non-reactive adhesive 14 is applied over the entire width of the inner surface 15 in evenly spaced adhesive strips in order to realize an enlarged adhesive surface. According to the schematic representation of the device 100 in Fig. 2, the device 100 further comprises a laterally projecting nozzle 102, which is oriented essentially transversely to the longitudinal direction LR or feed direction ZR.The laterally projecting nozzle 102 is adapted to apply the non-reactive adhesive 14 to the undercut surface 16 of the profile edge 12 of the first cover layer 11, adjacent to the inner surface 15 of the first cover layer 11. The laterally projecting nozzle 102 will be discussed in more detail later.

[0097] According to Fig. 2, the device 100 further comprises a further nozzle 103, which is arranged upstream of the laterally projecting nozzle 102. The further nozzle 103 serves to fill the narrow region 19 of the profile edge 12 of the first cover layer 11. For this purpose, the non-reactive adhesive is introduced into the narrow region 19 through the further nozzle 103. The non-reactive adhesive 14 introduced into the narrow region 19 is preferably foamed or is foamable, in particular self-foaming. The non-reactive adhesive 14 applied to the undercut surface 16 and the non-reactive adhesive 14 filled into the narrow region 19 are the same. The narrow region 19 in the filled, in particular foamed, state is shown by way of example in Fig. 4, for example. Alternatively, a prefabricated seal can be pressed into the narrow region 19. This is preferably done using a press-in wheel. Other seal insertion devices are possible.

[0098] Fig. 2 also shows that the additional nozzle 103 is positioned upstream of the laterally projecting nozzle 104. Likewise, the laterally projecting nozzle 102 is positioned upstream of the adhesive application device 101. The nozzles 102, 103 are aligned transversely to the feed direction ZR. The nozzles 102, 103 are not shown in Fig. 1.

[0099] 1 and 2, it can be seen that a device 105 for applying a self-expanding plastic material 17 is arranged downstream of the adhesive application device 101. The device 105 extends over the entire width B of the inner surface 15 of the first cover layer 11. The self-expanding plastic material 17 is a self-foaming mass which, in the foamed state, forms the core layer 17. The core layer 17 can therefore also be referred to as a foam core. Not shown in Fig. 1 for the sake of simplicity is a second feed and transport device 104 of the apparatus 100 which, during panel production, guides the second cover layer 18 above the first cover layer 11 and parallel thereto at a vertical distance therefrom. This preferably takes place in the feed direction ZR first downstream of the device 105 for applying the core layer mass.

[0100] Fig. 2 shows that the laterally projecting nozzle 102 protrudes laterally transversely to the longitudinal direction LR beyond the adhesive application device 101 when the non-reactive adhesive 14 is introduced into the undercut 13. The arrows drawn at the location of the nozzles 102, 103 in Fig. 2 represent the application direction of the adhesive 14 onto the undercut surface 16 or of the foaming material into the narrow area 19. The nozzles 102, 103 and the adhesive application device 101 are stationary.

[0101] In the following, the production of the above-mentioned sandwich panel 10 is described using a method carried out with the device 100.

[0102] In a first method step, the first cover layer 11 of the sandwich panel 10 is fed by the first feed and transport device 104 to the adhesive application device 101, the laterally projecting nozzle 102 and the further nozzle 103, wherein the first cover layer 11 is moved in the longitudinal direction LR of the device 100 during the following steps.

[0103] In the feed direction ZR, the further nozzle 103 first fills the narrow region 19 of the profile edge 12 of the first cover layer 11 with the non-reactive adhesive 14, which is foamed or foams up independently. Subsequently, the laterally projecting nozzle 102 applies the non-reactive adhesive 14 to the undercut surface 16 in such a way that the adhesive 14 comes to rest on the undercut surface 16 in beads running next to one another in the feed direction ZR. This is shown by way of example in Fig. 5. Thereafter, the adhesive application device 101 applies the non-reactive adhesive 14 to the inner surface 15 of the first cover layer 11 adjacent to the undercut 13. This takes place across the entire width of the inner surface 15, with regularly spaced adhesive beads being applied to the inner surface 15. At least the adhesive application device 101 and the laterally projecting nozzle 102 use the same adhesive supply, iePump, adhesive tank, control, etc.

[0104] It is possible for the nozzles 102, 103 to be arranged differently with respect to the adhesive application device 101. For example, the nozzles 102, 103 can be arranged downstream of the adhesive application device 101.

[0105] After the non-reactive adhesive 14 has been applied to the inner surface 15 and the undercut surface 16, the first cover layer 11 is fed to the device 105, which applies a self-foaming plastic compound at least to the inner surface 15 of the first cover layer 11. The second cover layer 18 is then guided through the second feed and transport device 104 such that it lies opposite the inner surface 15 of the first cover layer 11 and is spaced from the inner surface 15. The two cover layers 11, 18 are then guided or moved in parallel, whereby the applied plastic compound foams and fills the space between the cover layers 11, 18. In the process, the plastic compound also expands into the undercut 13 and, in addition to the adhesive 14 on the inner surface 15, comes into contact with the adhesive 14 on the undercut surface 16. After the plastic compound has hardened, a solid core layer is formed.Preferably, this forms a foam core.

[0106] The non-reactive adhesive 14 is a hot-melt adhesive that is applied to the inner surface 15 or the undercut surface 16 using the generally known hot-melt process. The hot-melt adhesive comprises, as its first component, at least one styrene block copolymer SC, in particular with a proportion of at least 5 wt. %, preferably at least 15 wt. %, more preferably at least 20 wt. %. The first component of the styrene block copolymer SC can, for example, make up 5-45 wt. %, preferably 15-45 wt. %, more preferably 20-40 wt. % of the total weight of the hot-melt adhesive; as its second component, at least one tackifying resin TR, in particular with a proportion of 15-55 wt. %, preferably 20-50 wt. %; and at least one plasticizer PL, selected from process oils and liquid polyolefin resins.The use of such a non-reactive hot melt adhesive has the great advantage that a particularly high-strength bond is formed between the core layer and the inner surface 15 or the undercut surface 16 of the first cover layer 11 and the risk of blistering during use is significantly reduced.

[0107] List of reference symbols

[0108] 10 sandwich panels

[0109] 11 first top layer

[0110] 12 profile edge

[0111] 13 Undercut

[0112] 14 non-reactive adhesive

[0113] 15 Inner surface of the first cover layer

[0114] 16 undercut surface

[0115] 17 Plastic material, core layer

[0116] 18 second top layer

[0117] 19 narrow range

[0118] 21 liaison point

[0119] 22 Profile edge of the second surface layer

[0120] 100 Device for producing a sandwich panel

[0121] 101 Adhesive application device

[0122] 102 side-projecting nozzle

[0123] 103 additional nozzles

[0124] 104 first feeding and transport device

[0125] 105 downstream facility

[0126] RZ feed direction

[0127] LR Longitudinal direction of the device

[0128] B Width of the inner surface of the first cover layer

Claims

Claims 1. A method for producing a sandwich panel (10), in particular for buildings and / or goods transport, in which a first cover layer (11) of the sandwich panel (10) is fed to at least one adhesive application device (101) for large-area adhesive application, wherein the first cover layer (11) has a profile edge (12) running in the feed direction (ZR) and having at least one undercut (13); a non-reactive adhesive (14) is applied by the adhesive application device (101) to an inner surface (15), in particular a large-area one, of the first cover layer (11); and the non-reactive adhesive (14) is applied by at least one laterally projecting nozzle (102) to at least one undercut surface (16) of the profile edge adjacent to the inner surface (15) of the first cover layer (11), wherein the nozzle (102) protrudes at least partially into the undercut (13);at least one self-expanding plastic material (17), in particular a foaming mass, is applied to the applied non-reactive adhesive (14); a second cover layer (18) of the sandwich panel (10) is guided opposite the first cover layer (11) at a distance such that the two cover layers (11, 18) are bonded together to form the sandwich panel (10) by expanding the applied plastic material (17); 2. Method according to claim 1, characterized in that the non-reactive adhesive (14) is applied to the undercut surface (16) in the feed direction (RZ) before and / or after the adhesive application device (101).

3. Method according to claim 1 or 2, characterized in that when applying the non-reactive adhesive to the inner surface (15) of the first cover layer (11), the adhesive application device (101) and / or when applying the non-reactive adhesive to the undercut surface (16) of the profile edge (12) is stationary, in particular is fixed, wherein the first cover layer (11) runs in the feed direction (ZR), in particular moving forward.

4. Method according to one of the preceding claims, characterized in that the non-reactive adhesive (14) is applied to the inner surface (15) of the first cover layer (11) and / or to the undercut surface (16) of the profile edge (12) in a multi-line and / or bead-like manner.

5. Method according to one of the preceding claims, characterized in that the profile edge (12) comprises at least one narrow region (19) adjacent to the undercut surface (16), which is filled at least in sections with the non-reactive adhesive (14) by the laterally projecting nozzle (102) and / or a further, in particular laterally projecting, nozzle (103).

6. Method according to one of the preceding claims, characterized in that the adhesive application device (101) and the laterally projecting nozzle (102) use one and the same adhesive supply.

7. Method according to one of the preceding claims, characterized in that exclusively non-reactive adhesive (14) is applied to the inner surface (15) of the first cover layer (11) and / or to the undercut surface (16) of the profile edge (12).

8. Method according to one of the preceding claims, characterized in that at least one hot melt adhesive is used as the non-reactive adhesive (14), which is applied in particular by the hot melt method.

9. The method according to claim 8, characterized in that the hot melt adhesive comprises: a. as a first component, at least one styrene block copolymer SC, in particular with a proportion of at least 5% by weight, preferably at least 20% by weight; b. as a second component, at least one tackifying hydrocarbon resin TR, in particular in a proportion of 15-55% by weight, preferably 20-50% by weight, c. at least one plasticizer PL, selected from process oils and liquid hydrocarbon resins, in particular in the form of polyolefin resins.

10. A device (100) for producing a sandwich panel (10), in particular for buildings and / or goods transport, comprising: at least one first feed and transport device (104) which runs in a longitudinal direction (LR) of the device (100) and is adapted to feed and transport a first cover layer (11) of the sandwich panel (10); at least one adhesive application device (101) for large-area adhesive application, which is adapted to apply a non-reactive adhesive, in particular hot melt adhesive, to the inner surface (15) of the first cover layer (11) of the sandwich panel (10), wherein the feed and transport device (104) runs below the adhesive application device (101) in the longitudinal direction (LR) of the device (100);at least one laterally projecting nozzle (102) which is oriented substantially transversely to the longitudinal direction (LR) of the device (100) and is adapted to apply the non-reactive adhesive (14) to at least one undercut surface (16) of a profile edge (12) of the first cover layer (11) adjacent to the inner surface (15) of the first cover layer (11); at least one downstream device (105) for applying a self-expanding plastic material (17), in particular a foaming mass; at least one second feed and transport device (104) which is adapted to feed a second cover layer (18) of the sandwich panel (10) at a distance from the first cover layer (11) in such a way that the two cover layers (11, 18) bond to one another to form the sandwich panel (10) by expanding the applied plastic material (17); 11. Device (100) according to claim 10, characterized in that the at least one laterally projecting nozzle (102) projects laterally transversely to the longitudinal direction (LR) beyond the adhesive application device (101).

12. Device (100) according to claim 10 or 11, characterized in that the laterally projecting nozzle (102) comprises at least one end-side nozzle opening for filling a narrow region (19) of the profile edge (12) adjacent to the undercut surface (16) and / or at least one underside nozzle opening, in particular a plurality of such nozzle openings, for applying the non-reactive adhesive to the undercut surface (16) in a multi-line manner.

13. Device (100) according to one of claims 10 to 12, characterized in that at least one further nozzle (103) is arranged upstream of the laterally projecting nozzle (102), which is adapted to fill at least in sections a narrow region (19) of the profile edge (12) adjacent to the undercut surface (16) with the non-reactive adhesive (14).

14. Device (100) according to one of claims 10 to 13, characterized in that the adhesive application device (101) and / or the device (105) for applying a self-expanding plastic material (17) extend transversely to the longitudinal direction (LR) of the device (100), in particular over the entire width (B) of the inner surface (15) of the first cover layer (11).

15. Sandwich panel (10) for a building and / or the transport of goods, with a first and a second cover layer (18) which are arranged at a distance from one another and delimit an intermediate space which is filled by a foam core, characterized in that on an inner surface (15) of the first cover layer (11) and on an undercut surface (16) of a profile edge (12) of the first cover layer (11) adjacent to the inner surface (15) at least one non-reactive adhesive, in particular hot melt adhesive, is applied, which firmly bonds the foam core to the first cover layer (11).

16. Sandwich panel (10) according to claim 15, characterized in that the two cover layers (11, 18) are formed from metal, in particular from coated and uncoated metallic and non-metallic materials.

17. Sandwich panel (10) according to claim 15 or 16, characterized in that the sandwich panel (10) is produced by a method according to claim 1 and / or with a device (100) according to claim 10.

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