Sandwich panel containing polyarylene ethersulfone polymer

Abstract

The present invention relates to a sandwich panel comprising an upper surface layer (UTL) containing a polyarylene ethersulfone polymer and fiber reinforcement, a foam core layer (FCL) containing a polyarylene ethersulfone polymer, and a lower surface layer (LTL) containing a polyarylene ethersulfone polymer and fiber reinforcement, wherein the upper surface layer (UTL) is bonded to the foam core layer (FCL) via a first film (F1) containing a blend of polyarylene ethersulfone polymer and further polymers, and the lower surface layer (LTL) is bonded to the foam core layer (FCL) via a second film (F2) containing a blend of polyarylene ethersulfone polymer and further polymers. Another aspect of the present invention relates to a process for manufacturing sandwich panels, as well as the use of sandwich panels as building components for the aerospace industry and for constructing rotor blades for wind turbines. Yet another aspect of the present invention relates to a process for reusing sandwich panels.

Description

[Technical Field]

[0001] The present invention relates to a sandwich panel comprising an upper surface layer (UTL) containing a polyarylene ethersulfone polymer and fiber reinforcement, a foam core layer (FCL) containing a polyarylene ethersulfone polymer, and a lower surface layer (LTL) containing a polyarylene ethersulfone polymer and fiber reinforcement, wherein the upper surface layer (UTL) is bonded to the foam core layer (FCL) via a first film (F1) containing a blend of polyarylene ethersulfone polymer and further polymers, and the lower surface layer (LTL) is bonded to the foam core layer (FCL) via a second film (F2) containing a blend of polyarylene ethersulfone polymer and further polymers. Another aspect of the present invention relates to a process for manufacturing sandwich panels, as well as the use of sandwich panels as building components for the aerospace industry and for the construction of rotor blades for wind turbines. Yet another aspect of the present invention relates to a process for the reuse of sandwich panels.

[0002] Composite materials are used in a variety of industrial applications due to their unique combination of mechanical properties and low density. This enables lightweight structures in many fields, particularly in the aerospace industry or for constructing rotor blades for wind turbines. The weight reduction generally contributes to the demand for CO2 reduction in these applications.

[0003] To meet actual performance challenges, different types of materials are typically combined into a single component, but this is incompatible with another social demand: the need for a circular economy. Therefore, new options are needed for composite materials as well, at the end of their lifespan.

[0004] One segment where a significant amount of sandwich panels are consumed is aircraft interiors. Sandwich panels are used intensively to manufacture and customize various areas of the interior, such as overhead storage compartments, floor panels, roof panels, side panels, and cabin walls (EAFranco-Urquiza et al., Polymers 2021, 13, 3258). The growth of air traffic and the constant need to replace damaged parts or to carry out complete overhauls often create a high demand for such materials.

[0005] Regarding the reuse of sandwich panels, one option may be to dismantle the entire component from its primary use, crush the component, and reuse the material in a molded composition with other thermoplastic materials.

[0006] Such concepts only work when thermoplastic polymers are used as matrix materials in composites. For such pulverized recycled materials, the likelihood of finding high-value applications increases if only one type of thermoplastic material is used in the various layers of the component. This is because it is generally known that most polymer mixtures are immiscible, which limits their mechanical properties (C. Koning et al., Progr. Polym Sci. 23, 707, 1998).

[0007] In practice, most sandwich panels for aircraft interiors are based on a honeycomb core material made from polyaramid (Nomex® Honeycomb), which is covered with a prepreg, typically based on phenolic or epoxy resin, although the composition varies. Because the resin forms a three-dimensional network structure during the curing process, the final part cannot be remelted, severely limiting the reuse of such parts.

[0008] Therefore, other options for the manufacture of sandwich panels are being discussed. For the manufacture of sandwich panels, lightweight core materials are usually assembled with fiber reinforcement layers to provide the required bending strength for the panels. To replace expensive honeycomb structures, thermoplastic foams with a density of 30 - 750 g / l can be used as the core material. Since high flame retardancy (low smoke and low heat release) is required for aircraft use, only polyetherimide, a high heat-resistant polymer, can be used as the foam core.

[0009] The fiber-reinforced outer layer using a thermoplastic matrix material can be manufactured by impregnating fibers or fabrics with a matrix polymer by solvent impregnation or pultrusion.

[0010] The main challenge in the manufacture of thermoplastic sandwich panels is the lamination of the foam core and the fiber-reinforced outer layer.

[0011] To laminate different layers during panel assembly, special solvent-based adhesives are required, which significantly reduce the properties of the recycled materials. Furthermore, the solvents used may cause cracks in the foam core and reduce mechanical performance.

[0012] Therefore, the object of the present invention was to provide a sandwich panel in which the adhesive layer for lamination is solvent-free. The sandwich panel should preferably meet the high flame retardancy requirements for aircraft use. Furthermore, the sandwich panel should preferably be reusable after its life.

[0013] This object is achieved by an upper surface layer (UTL) comprising at least one polyarylene ether sulfone polymer and at least one fiber reinforcement, a foam core layer (FCL) comprising at least one polyarylene ether sulfone polymer, A lower surface layer (LTL) comprising at least one polyarylene ethersulfone polymer and at least one fiber reinforcing material Includes, The upper surface layer (UTL) is bonded to the foam core layer (FCL) via a first film (F1) comprising a blend of at least one polyarylene ethersulfone polymer and at least one further polymer. The lower surface layer (LTL) is bonded to the foam core layer (FCL) via a second film (F2) comprising a blend of at least one polyarylene ethersulfone polymer and at least one further polymer. This is achieved through sandwich panels.

[0014] In another embodiment, the sandwich panel is An upper surface layer (UTL) comprising at least one polyarylene ethersulfone polymer and at least one fiber reinforcing material, A foam core layer (FCL) containing at least one type of polyarylene ethersulfone polymer, A lower surface layer (LTL) comprising at least one polyarylene ethersulfone polymer and at least one fiber reinforcing material It consists of, The upper surface layer (UTL) is bonded to the foam core layer (FCL) via a first film (F1) comprising a blend of at least one polyarylene ethersulfone polymer and at least one further polymer. The lower surface layer (LTL) is bonded to the foam core layer (FCL) via a second film (F2) comprising a blend of at least one polyarylene ethersulfone polymer and at least one further polymer.

[0015] Surprisingly, the sandwich panel according to the present invention has been found to be solvent-free. The sandwich panel according to the present invention has good mechanical properties, good adhesion between different layers, and good flexural strength, resulting in good adhesion between different layers even after the sandwich panel has been bent.

[0016] Surprisingly, it was found that solvent-free construction of a polyarylene ethersulfone-based foam core and reinforcing layer can be achieved by using a film having a glass transition temperature (Tg) at least 5K lower than the glass transition temperature (Tg) of the foam core. By applying temperature and appropriate pressure, such a film provides excellent adhesion between the core and the reinforcing surface layer.

[0017] Surprisingly, it was found that solvent-free construction of sandwich panels can be achieved by using a polyarylene ethersulfone-based foam core layer (FCL), a polyarylene ethersulfone-based reinforced upper layer (UTL), a polyethersulfone-based reinforced lower layer (LTL), and two films (F1, F2) comprising a blend of polyarylene ethersulfone and further polymers, having a glass transition temperature Tg at least 5K lower than that of the polyethersulfone-based foam core layer (FCL).

[0018] Surprisingly, the sandwich panel according to the present invention is reusable. After the sandwich panel of the present invention is crushed, the crushed material can be reused for high-value applications in various industries.

[0019] Polyarylene ether sulfone polymer In the sandwich panel according to the present invention, the surface layer (UTL), the foam core layer (FCL), the lower surface layer (LTL), the first film (F1), and the second film (F2) each independently contain at least one type of polyarylene ethersulfone.

[0020] Polyarylene ethersulfone polymers are high-performance thermoplastics characterized by high heat resistance, good mechanical properties, and inherent flame retardancy (EMKoch, H.-M.Walter, Kunststoffe 80 (1990) 1146; E.Doering, Kunststoffe 80, (1990) 1149, N.Inchaurondo-Nehm, Kunststoffe 98, (2008) 190).

[0021] Polyarylene ethersulfone polymers can be formed, in particular, by either a hydroxide method in which a salt is first formed from a dihydroxy component and a hydroxide, or by a carbonate method.

[0022] General information regarding the formation of polyarylene ethersulfone polymers by hydroxide methods can be found, in particular, in RN. Johnson et al., J. Polym. Sci. A-1 5(1967)2375, and the carbonate method is described in J. E. McGrath et al., Polymer 25(1984)1827.

[0023] Methods for forming polyarylene ethersulfone polymers from aromatic bishalogen compounds and aromatic bisphenols or salts thereof in an aprotic solvent in the presence of one or more alkali metal or ammonium carbonates or bicarbonates are known to those skilled in the art and are described, for example, in European Patent Application Publication No. 297363 and European Patent Application Publication No. 135130.

[0024] High-performance thermoplastic resins, such as polyarylene ethersulfone polymers, are formed by polycondensation reactions typically carried out at high reaction temperatures in dipolar aprotic solvents, such as DMF, DMAc, sulfolane, DMSO, and NMP.

[0025] European Patent Application Publication No. 0412499 describes a method for forming polyarylene ethersulfone polymers. The dihalogen components used in the method of European Patent Application Publication No. 0412499 are, for example, 4,4'-di-chloro-diphenylsulfone or 4,4'-difluorodiphenylsulfone. Dihydroxy components described in European Patent Application Publication No. 0412499 include bisphenol A, 4,4'-dihydroxydiphenylsulfone, and 4,4'-dihydroxybenzophenone. The polycondensation described in European Patent Application Publication No. 0412499 is carried out in the presence of sodium carbonate or sodium bicarbonate.

[0026] In a preferred embodiment, the polyarylene ethersulfone polymer contained in the sandwich panel is composed of: (A1) At least one dihalogen compound selected from the group consisting of 4,4'-dichlorodiphenylsulfone and 4,4'-difluorodiphenylsulfone is added to the reaction mixture (R G ) containing 80% or more by weight based on the total weight of component (A1) in the dihalogen component, (B1) At least one dihydroxy compound selected from the group consisting of 4,4'-dihydroxy-diphenylsulfone, bisphenol A, 4,4'-dihydroxybiphenyl, and hydroquinone is added to the reaction mixture (R G ) containing 80% or more by weight based on the total weight of component (B1) in the dihydroxy component Reaction mixture containing (R G It is obtained by converting ).

[0027] Therefore, another object of the present invention is At least one polyarylene ethersulfone polymer contained in the upper surface layer (UTL), at least one polyarylene ethersulfone polymer contained in the foam core layer (FCL), at least one polyarylene ethersulfone polymer contained in the lower surface layer (LTL), at least one polyarylene ethersulfone polymer contained in the first film (F1), and at least one polyarylene ethersulfone polymer contained in the second film (F2) are each independently of each other as components. (A1) At least one dihalogen compound selected from the group consisting of 4,4'-dichlorodiphenylsulfone and 4,4'-difluorodiphenylsulfone is added to the reaction mixture (R G ) containing 80% or more by weight based on the total weight of component (A1) in the dihalogen component, (B1) At least one dihydroxy compound selected from the group consisting of 4,4'-dihydroxy-diphenylsulfone, bisphenol A, 4,4'-dihydroxybiphenyl, and hydroquinone is added to the reaction mixture (R G ) containing 80% or more by weight based on the total weight of component (B1) in the dihydroxy component Reaction mixture containing (R G A sandwich panel which is at least one polymer obtained by converting ).

[0028] The polyarylene ethersulfone polymer contained in the sandwich panel according to the present invention preferably comprises the above components (A1), (B1), and a reaction mixture (R) further comprising components (C) and (D). G It is formed by transforming ).

[0029] Components (A1) and (B1) will react with each other in the polycondensation reaction.

[0030] Component (D) acts as a solvent. Component (C) acts as a base to deprotonate component (B1) during the condensation reaction.

[0031] Therefore, the reaction mixture (R G ) is the mixture used to form the polyarylene ether sulfone polymer in the method provided by the present invention. Therefore, all details in this specification regarding the reaction mixture (R G ) relate to the mixture existing before the polycondensation. During the method of the present invention, polycondensation occurs, and by polycondensing components (A1) and (B1), the reaction mixture (R G ) is converted into the target product, the polyarylene ether sulfone polymer. The mixture containing the target product, the polyarylene ether sulfone polymer, obtained after polycondensation is also called the product mixture (P G ).

[0032] Generally, the components of the reaction mixture (R G ) react together. The individual components may be mixed and then reacted in a preceding step. It is also possible to supply the individual components to a reactor, where they are mixed and subsequently reacted.

[0033] In the method of the present invention, the individual components of the reaction mixture (R G ) are generally converted together. This conversion is preferably carried out in a single step. That is, the deprotonation of component (B1) and the condensation reaction between components (A1) and (B1) occur in a single reaction step without isolating an intermediate, for example, the deprotonated species of component (B1).

[0034] Component (A1) Component (A1), also called the dihalogen component, is present in the reaction mixture (R G 8) in the form of at least one dihalogen compound. As used herein, "at least one dihalogen compound" means exactly one dihalogen compound and also a mixture of two or more dihalogen compounds.

[0035] Therefore, component (A1) may contain not only a single dihalogen compound but also a mixture of two or more dihalogen compounds.

[0036] Preferably, component (A1) is the reaction mixture (R G The compound contains at least 50% by weight of at least one dihalogen compound selected from the group consisting of 4,4'-dichlorodiphenyl sulfone and 4,4'-difluorodiphenyl sulfone, based on the total weight of component (A1) in the compound. The weight percentages here relating to component (A1) further relate to the sum of the 4,4'-dichloro-diphenyl sulfone and the 4,4'-difluorodiphenyl sulfone used. 4,4'-dichlorodiphenyl sulfone is preferred over 4,4'-difluorodiphenyl sulfone. 4,4'-dichlorodiphenyl sulfone is particularly preferred.

[0037] In one embodiment, component (A1) is the reaction mixture (R G Based on the total weight of component (A1) in the mixture, it contains at least 80% by weight, preferably 90% by weight, and more preferably 95% by weight, of at least one dihalogen compound selected from the group consisting of 4,4'-dichlorodiphenyl sulfone and 4,4'-difluorodiphenyl sulfone. The weight percentages here relating to component (A1) further relate to the sum of the 4,4'-dichloro-diphenyl sulfone and 4,4'-difluoro-diphenyl sulfone used.

[0038] In one particularly preferred embodiment, component (A1) contains 50% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more, and especially 95% by weight or more of 4,4'-dichlorodiphenyl sulfone.

[0039] Furthermore, the reaction mixture (R G It is particularly preferable that the compound (A1) contains no further dihalogen compounds in addition to the dihalogen compound of component (A1).

[0040] In a further particularly preferred embodiment, component (A1) comprises 4,4'-dichlorodiphenylsulfone.

[0041] Ingredients (B1) The component (B1), also called the dihydroxy component, reacts with the mixture (R) in the form of at least one dihydroxy compound. G ) is present in. In this specification, “at least one dihydroxy compound” means exactly one dihydroxy compound, and also a mixture of two or more dihydroxy compounds.

[0042] Therefore, component (B1) may include not only a single dihydroxy compound, but also a mixture of two or more dihydroxy compounds.

[0043] In one embodiment, component (B1) is the reaction mixture (R G Based on the total weight of component (B1) in the mixture, it contains 50% by weight or more of at least one dihydroxy compound selected from the group consisting of 4,4'-dihydroxy-diphenylsulfone, bisphenol A (2,2-bis(4-hydroxyphenyl)propane), 4,4'-dihydroxybiphenyl, and hydroquinone. The weight percentages here relating to component (B1) further relate to the total of 4,4'-dihydroxydiphenylsulfone, bisphenol A (2,2-bis-(4-hydroxyphenyl)propane), 4,4'-dihydroxybenzophenone, and hydroquinone used. Among the above dihydroxy compounds, 4,4'-dihydroxydiphenylsulfone, bisphenol A, and 4,4'-dihydroxybiphenyl are preferred, and 4,4'-dihydroxydiphenylsulfone is particularly preferred.

[0044] In one embodiment, component (B1) is the reaction mixture (R GBased on the total weight of component (B1) in the mixture, it contains 80% or more by weight, preferably 90% or more by weight, and more preferably 95% or more by weight, of at least one dihydroxy compound selected from the group consisting of 4,4'-dihydroxydiphenylsulfone, bisphenol A (2,2-bis-(4-hydroxyphenyl)propane), 4,4'-dihydroxybiphenyl, and hydroquinone. The weight percentages here relating to component (B1) further relate to the total of 4,4'-dihydroxydiphenylsulfone, bisphenol A (2,2-bis-(4-hydroxyphenyl)-propane), 4,4'-dihydroxybiphenyl, and hydroquinone used.

[0045] In one particularly preferred embodiment, component (B1) contains 50% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more, and especially 95% by weight or more of bisphenol A.

[0046] In one particularly preferred embodiment, component (B1) contains 50% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more, and especially 95% by weight or more of 4,4'-dihydroxydiphenyl sulfone.

[0047] In one particularly preferred embodiment, component (B1) contains 50% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more, and especially 95% by weight or more of 4,4'-dihydroxybiphenyl.

[0048] Furthermore, the reaction mixture (R G It is particularly preferable that the compound (B1) contains no further dihydroxy compounds in addition to the dihydroxy compound of component (B1).

[0049] In a further particularly preferred embodiment, component (B1) comprises 4,4'-hydroxydiphenylsulfone.

[0050] Reaction mixture (R GSince ) contains potassium carbonate as component (C), the hydroxyl group of the dihydroxy compound used as component (B1) is partially in a deprotonated form in the reaction mixture (R G ) may exist within.

[0051] Ingredients (C) Reaction mixture (R G ) contains potassium carbonate as component (C), which is also known as the carbonate component. The potassium carbonate used is preferably anhydrous.

[0052] In a preferred embodiment, component (C) is the reaction mixture (R G It contains 90% or more potassium carbonate by weight, based on the total weight of component (C) in it.

[0053] In one embodiment, component (C) is the reaction mixture (R G Based on the total weight of component (B1) in the mixture, it contains potassium carbonate having a volume-average particle size of less than 50 μm, comprising 80% by weight or more, preferably 90% by weight or more, and more preferably 98% by weight or more.

[0054] In one particularly preferred embodiment, component (C) is potassium carbonate.

[0055] Ingredients (D) Reaction mixture (R G Preferably, the mixture contains at least one aprotic polar solvent as component (D). In the present invention, "at least one aprotic polar solvent" means exactly one aprotic polar solvent and a mixture of two or more aprotic polar solvents.

[0056] Useful aprotic polar solvents include, for example, anisole, dimethylformamide, dimethyl sulfoxide, sulfolane, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and mixtures thereof.

[0057] For use as an aprotic polar solvent, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and mixtures thereof are also preferred. For use as an aprotic polar solvent, N-methyl-2-pyrrolidone is particularly preferred.

[0058] In a preferred embodiment, component (D) is the reaction mixture (R G The mixture contains at least 90% by weight of at least one solvent selected from the group consisting of N-methyl-2-pyrrolidone and N-ethyl-2-pyrrolidone, based on the total weight of component (D) in the mixture. N-methyl-2-pyrrolidone is particularly preferred for use as component (D).

[0059] In a preferred embodiment, component (D) consists of N-methyl-2-pyrrolidone, also known as NMP or N-methylpyrrolidone.

[0060] In a more preferred embodiment, the reaction mixture does not contain any further aprotic polar solvents in addition to the aprotic polar solvent of component (D).

[0061] To form a polyarylene ethersulfone polymer, the reaction mixture (R G The reaction is preferably carried out under carbonate conditions. The reaction involved is a polycondensation reaction and is generally carried out at a temperature in the range of 80 to 250°C, preferably in the range of 100 to 220°C, with the upper limit of the temperature determined by the boiling point of the aprotic polar solvent (component D) at atmospheric pressure (10¹³.25 mbar). The reaction is generally carried out at atmospheric pressure. The reaction time interval is preferably in the range of 0.5 to 12 hours, particularly in the range of 2 to 10 hours.

[0062] The polyarylene ethersulfone polymer obtained by the present invention can be isolated by precipitation of the polymer solution in water or in a mixture of water and a further solvent, such as an alcohol. Subsequently, the precipitated polyarylene ethersulfone polymer can be extracted with water and then dried. In one embodiment of the present invention, precipitation may be carried out in an acidic medium. Suitable acids include, for example, organic or inorganic acids, such as carboxylic acids, such as acetic acid, propionic acid, succinic acid, or citric acid, and also mineral acids, such as hydrochloric acid, sulfuric acid, or phosphoric acid.

[0063] Suitable methods for forming the above-mentioned polyarylene ethersulfone polymers are known to those skilled in the art, for example, in Herman F. Mark, "Encyclopedia of Polymer Science and Technology," 3rd edition, Vol. 4, 2003, Chapter "Polsulfones," pp. 2-8, and also in Hans R. Kricheldorf, "Aromatic Polyethers," in Handbook of Polymer Synthesis, 2nd edition, 2005, pp. 427-443.

[0064] A preferred polyarylene ethersulfone polymer comprises at least one of the following construction blocks Ia to Ic as a structural repeating unit. [ka]

[0065] It is also particularly preferable that the polyarylene ethersulfone polymer is essentially composed of at least one different building block selected from the group consisting of Ia, Ib, and Ic.

[0066] Polyarylene ethersulfone polymers composed of repeating units of formula Ib are even more particularly preferred. Polyethersulfone (PESU) is another name for these polyarylene ethersulfone polymers.

[0067] The abbreviations PESU and PSU used herein conform to DIN EN ISO 1043-1 (Plastics - Symbols and abbreviated terms - Part 1: Basic polymers and their special characteristics (ISO 1043-1:2001); German version of EN ISO 1043-1:2002).

[0068] Block copolymers or other copolymers constructed from repeating units of formulas Ia, Ib, and Ic are even more particularly preferred.

[0069] The weight-average molecular weight (M) of the polyarylene ethersulfone polymer obtained by the method of the present invention W The weight-average molecular weight (M) is generally in the range of 10,000 to 150,000 g / mol, preferably in the range of 15,000 to 120,000 g / mol, and more preferably in the range of 18,000 to 100,000 g / mol. W The ) is measured using gel permeation chromatography (GPC). This measurement is performed using gel permeation chromatography (GPC). Dimethylacetamide (DMAc) was used as the solvent, and a narrow distribution of polymethyl methacrylate was used as the measurement standard.

[0070] Polyarylene ethersulfone polymers having a viscosity number (VN) of 40–120 ml / g are preferred (measured as a 1 wt% solution in N-methyl-2-pyrrolidone at 23°C according to ISO 1628). Such polymers are available from BASF SE as Ultrason® E.

[0071] The terminal groups of polyarylene ethersulfone polymers depend on the reaction conditions and the molar ratio of components (A1) and (B1), and are generally either halogen groups, particularly chlorine groups, or etherifying groups, particularly alkyl ether groups. Etherified terminal groups can be obtained by reacting the terminal OH / phenoxide group with a suitable etherifying agent.

[0072] Suitable etherifying agents include monofunctional alkyl halides or aryl halides, such as C1-C6 alkyl chlorides, C1-C6 alkyl bromides, or C1-C6 alkyl iodides, preferably methyl chloride, or benzyl chloride, benzyl bromide, or benzyl iodide, or mixtures thereof. The terminal groups of the polyarylene ethersulfone polymer according to the present invention are preferably halogen groups, particularly chlorine, and also alkoxy groups, particularly methoxy, aryloxy groups, particularly phenoxy or benzyloxy.

[0073] Upper surface layer (UTL) / Lower surface layer (LTL) The upper surface layer (UTL) comprises at least one polyarylene ethersulfone and at least one fiber reinforcing material. In this specification, "at least one polyarylene ethersulfone polymer" means just one polyarylene ethersulfone polymer and also a mixture of two or more different polyarylene ethersulfone polymers. Preferably, the upper surface layer (UTL) comprises one polyarylene ethersulfone polymer.

[0074] With respect to at least one polyarylene ethersulfone polymer contained in the upper surface layer (UTL), the above descriptions, explanations, and preferred features concerning polyarylene ethersulfone polymers also apply.

[0075] The glass transition temperature (Tg) of the polyarylene ethersulfone polymer contained in the upper surface layer (UTL) is preferably in the range of 180 to 230°C, more preferably in the range of 185 to 228°C, and most preferably in the range of 185 to 226°C. The glass transition temperature (Tg) is determined by DSC measurement according to ISO 11357-1 using a heating rate of 10 K / min.

[0076] Weight-average molecular weight (M) of polyarylene ethersulfone polymer contained in the upper surface layer (UTL) WThe weight-average molecular weight (M) is generally in the range of 50,000 to 150,000 g / mol, preferably in the range of 52,000 to 120,000 g / mol, and more preferably in the range of 53,000 to 100,000 g / mol. W The average molecular weight (M) of the polyarylene ethersulfone polymer contained in the upper surface layer (UTL) is measured using gel permeation chromatography (GPC). This measurement is performed using gel permeation chromatography (GPC). Dimethylacetamide (DMAc) was used as the solvent and a narrow distribution of polymethyl methacrylate was used as the measurement standard. In a preferred embodiment, the average molecular weight (M) of the polyarylene ethersulfone polymer contained in the upper surface layer (UTL) is measured. W ) is the average molecular weight (M) of the polyarylene ethersulfone polymer contained in the blend contained in the first and second films (F1, F2). W It is higher than ).

[0077] In a preferred embodiment, the upper surface layer (UTL) comprises at least one polyarylene ethersulfone polymer selected from the group consisting of polysulfone (PSU), polyethersulfone (PESU), and polybiphenylsulfone (PPSU).

[0078] In a particularly preferred embodiment, the polyarylene ethersulfone polymer contained in the upper layer (UTL) is polyethersulfone (PESU).

[0079] Furthermore, the upper surface layer (UTL) includes at least one fiber reinforcement. In this specification, "at least one fiber reinforcement" means exactly one fiber reinforcement, and also a mixture of two or more fiber reinforcements.

[0080] Suitable fiber reinforcement materials are selected from the group consisting of, for example, glass fibers and carbon fibers. Typically, reinforced thermoplastic laminates (RTLs) are used as the upper surface layer (UTL).

[0081] In a preferred embodiment, the upper surface layer (UTL) comprises, based on the total weight of the upper surface layer (UTL), 25 to 70% by weight of at least one polyarylene ethersulfone polymer and 30 to 75% by weight of at least one fiber reinforcing material.

[0082] The preparation of the upper surface layer (UTL) is known to those skilled in the art. The upper surface layer (UTL) can be prepared, for example, by impregnating at least one fiber-reinforced material with at least one polyarylene ethersulfone polymer in a molten state. A suitable procedure for preparing the upper surface layer (UTL) is, for example, to melt-press a layer of thermoplastic film together with a layer of fibers in a press to achieve a uniform distribution of thermoplastic material in the RTL. The fiber orientation of different fiber layers can be adapted to the needs of a particular application and can be 0 / 90 / +45 / -45. Consolidation in the press allows for easy processing of the RTL. The RTL can also be obtained by powder impregnation of the fabric. Details of these processes are given in Valente, M.polymers 2023, 15, 242.

[0083] The upper surface layer (UTL) and lower surface layer (LTL) included in the sandwich panel preferably have a thickness in the range of 0.1 to 0.5 mm, independently of each other. In a preferred embodiment, the upper surface layer (UTL) and lower surface layer (LTL) included in the sandwich panel preferably have the same thickness in the range of 0.1 to 0.5 mm.

[0084] Therefore, another object of the present invention is a sandwich in which the upper surface layer (UTL) and the lower surface layer (LTL) are independent of each other and have a thickness in the range of 0.1 to 0.5 mm.

[0085] The upper surface layer (UTL) and lower surface layer (LTL) contained in the sandwich panel preferably independently of each other, weighing 150-600 g / m². 2It has a basis weight within the range of [specify weight]. In a preferred embodiment, the upper surface layer (UTL) and lower surface layer (LTL) included in the sandwich panel are preferably 200 to 500 g / m². 2 They have the same basis weight within the range.

[0086] In another preferred embodiment, the upper surface layer (UTL) and lower surface layer (LTL) included in the sandwich panel contain the same polyarylene ethersulfone polymer.

[0087] In another preferred embodiment, the upper surface layer (UTL) and lower surface layer (LTL) included in the sandwich panel contain the same polyarylene ethersulfone polymer and the same fiber reinforcement. In another preferred embodiment, the upper surface layer (UTL) and lower surface layer (LTL) included in the sandwich panel contain the same polyarylene ethersulfone polymer, the same fiber reinforcement, and have the same thickness. In another preferred embodiment, the upper surface layer (UTL) and lower surface layer (LTL) included in the sandwich panel contain the same polyarylene ethersulfone polymer, the same fiber reinforcement, have the same thickness, and have the same basis weight.

[0088] In another preferred embodiment, the upper surface layer (UTL) and lower surface layer (LTL) contained in the sandwich panel contain the same polyarylene ethersulfone polymer, the same fiber reinforcement, have the same thickness, the same basis weight, and the same glass transition temperature.

[0089] In a particularly preferred embodiment, the upper surface layer (UTL) and the lower surface layer (LTL) are identical.

[0090] The same descriptions, explanations, and preferred features described above for the upper surface layer (UTL) also apply to the lower surface layer (LTL).

[0091] The lower surface layer (LTL) comprises at least one polyarylene ethersulfone and at least one fiber reinforcing material. In this specification, "at least one polyarylene ethersulfone polymer" means just one polyarylene ethersulfone polymer and also a mixture of two or more different polyarylene ethersulfone polymers. Preferably, the lower surface layer (LTL) comprises one polyarylene ethersulfone polymer.

[0092] With respect to at least one polyarylene ethersulfone polymer contained in the lower surface layer (LTL), the above descriptions, explanations, and preferred features concerning polyarylene ethersulfone polymers also apply.

[0093] The glass transition temperature (Tg) of the polyarylene ethersulfone polymer contained in the lower surface layer (LTL) is preferably in the range of 180 to 230°C, more preferably in the range of 185 to 227°C, and most preferably in the range of 185 to 225°C. The glass transition temperature is determined as described above.

[0094] Weight-average molecular weight (M) of polyarylene ethersulfone polymer contained in the lower surface layer (LTL) W The weight-average molecular weight (M) is generally in the range of 50,000 to 150,000 g / mol, preferably in the range of 52,000 to 120,000 g / mol, and more preferably in the range of 53,000 to 100,000 g / mol. W The average molecular weight (M) of the polyarylene ethersulfone polymer contained in the lower surface layer (LTL) is measured using gel permeation chromatography (GPC). This measurement is performed using gel permeation chromatography (GPC). Dimethylacetamide (DMAc) was used as the solvent and a narrow distribution of polymethyl methacrylate was used as the standard for measurement. In a preferred embodiment, the average molecular weight (M) of the polyarylene ethersulfone polymer contained in the lower surface layer (LTL) is measured. W ) is the average molecular weight (M) of the polyarylene ethersulfone polymer contained in the blend contained in the first and second films (F1, F2). W It is higher than ).

[0095] In a preferred embodiment, the lower surface layer (LTL) comprises at least one polyarylene ethersulfone polymer selected from the group consisting of polysulfone (PSU), polyethersulfone (PESU), and polybiphenylsulfone (PPSU).

[0096] In a particularly preferred embodiment, the polyarylene ethersulfone polymer contained in the lower layer (LTL) is polyethersulfone (PESU).

[0097] Furthermore, the lower surface layer (LTL) includes at least one fiber reinforcement. In this specification, "at least one fiber reinforcement" means exactly one fiber reinforcement, and also a mixture of two or more fiber reinforcements.

[0098] Suitable fiber reinforcement materials are selected from the group consisting of, for example, glass fibers and carbon fibers. Typically, reinforced thermoplastic laminates (RTL) are used as the lower surface layer (LTL).

[0099] In a preferred embodiment, the lower surface layer (LTL) comprises, based on the total weight of the lower surface layer (LTL), 25 to 70% by weight of at least one polyarylene ethersulfone polymer and 30 to 75% by weight of at least one fiber reinforcing material.

[0100] The preparation of the lower surface layer (LTL) is known to those skilled in the art. The lower surface layer (LTL) can be prepared, for example, by impregnating at least one fiber-reinforced material with at least one polyarylene ethersulfone polymer in a molten state. A suitable procedure for preparing the lower surface layer (LTL) is the same as that described above for the upper surface layer (UTL).

[0101] Foam core layer (FCL) The foam core layer (FCL) contains at least one polyarylene ethersulfone. In this specification, "at least one polyarylene ethersulfone polymer" means just one polyarylene ethersulfone polymer and also a mixture of two or more different polyarylene ethersulfone polymers. Preferably, the foam core layer (FCL) contains one polyarylene ethersulfone polymer.

[0102] Considering at least one polyarylene ethersulfone polymer contained in the foam core layer (FCL), the above description, explanation, and preference relating to the polyarylene ethersulfone polymer apply accordingly.

[0103] The glass transition temperature (Tg) of the polyarylene ethersulfone polymer contained in the foam core layer (FCL) is preferably in the range of 180 to 230°C, more preferably in the range of 185 to 228°C, and most preferably in the range of 185 to 225°C. The glass transition temperature is determined as described above.

[0104] Weight-average molecular weight (M) of polyarylene ethersulfone polymer contained in the foam core layer (FCL) W The weight-average molecular weight (M) is generally in the range of 50,000 to 150,000 g / mol, preferably in the range of 52,000 to 120,000 g / mol, and more preferably in the range of 53,000 to 100,000 g / mol. W The average molecular weight (M) of the polyarylene ethersulfone polymer contained in the foam core layer (FCL) is measured using gel permeation chromatography (GPC). This measurement is performed using gel permeation chromatography (GPC). Dimethylacetamide (DMAc) was used as the solvent and a narrow distribution of polymethyl methacrylate was used as the standard for measurement. In a preferred embodiment, the average molecular weight (M) of the polyarylene ethersulfone polymer contained in the foam core layer (FCL) is measured using gel permeation chromatography (GPC). Dimethylacetamide (DMAc) was used as the solvent and a narrow distribution of polymethyl methacrylate was used as the standard for measurement. W ) is the average molecular weight (M) of the polyarylene ethersulfone polymer contained in the blend contained in the first and second films (F1, F2). W It is higher than ).

[0105] In a preferred embodiment, the foam core layer (FCL) comprises at least one polyarylene ethersulfone polymer selected from the group consisting of polysulfone (PSU), polyethersulfone (PESU), and polybiphenylsulfone (PPSU).

[0106] In a particularly preferred embodiment, the polyarylene ethersulfone polymer contained in the foam core layer (FCL) is polyethersulfone (PESU).

[0107] The preparation of foam core layers (FCLs) is known to those skilled in the art. Foam core layers (FCLs) can be prepared by extrusion using a solvent as a blowing agent and special process parameters, for example, as described in German Patent Application Publication No. 4207057. Aqueous mixtures as blowing agents for preparing foam core layers (FCLs) are described in European Patent No. 1333051. Foaming with water is possible when a PESU mixture with a broad molecular weight distribution is used.

[0108] The foam core layer (FCL) included in the sandwich panel preferably has a thickness in the range of 0.76 to 50 mm.

[0109] Therefore, another object of the present invention is a sandwich panel in which the foam core layer (FCL) has a thickness in the range of 0.76 to 50 mm.

[0110] The foam core layer (FCL) contained in sandwich panels has a density of 25-200 kg / m³. 3 Density within the range of 35-155 kg / m³ 3 It has a density within the range.

[0111] Therefore, another object of the present invention is that the foam core layer (FCL) is 25-200 kg / m 3 This is a sandwich panel having a density within a certain range.

[0112] In another preferred embodiment, the foam core layer (FCL), upper surface layer (UTL), and lower surface layer (LTL) contained in the sandwich panel comprise the same polyarylene ethersulfone polymer.

[0113] First film (F1) / Second film (F2) The first film (F1) comprises at least one polyarylene ethersulfone. In this specification, "at least one polyarylene ethersulfone polymer" means just one polyarylene ethersulfone polymer and also a mixture of two or more different polyarylene ethersulfone polymers. Preferably, the first film (F1) comprises one polyarylene ethersulfone polymer.

[0114] With respect to at least one polyarylene ethersulfone polymer contained in the first film (F1), the above descriptions, explanations, and preferred features relating to polyarylene ethersulfone polymers also apply.

[0115] In preferred embodiments, at least one polyarylene ethersulfone polymer contained in the blend has a viscosity number (VN) in the range of 45 to 58 ml / g, measured at 25°C, preferably in N-methyl-2-pyrrolidone, according to ISO 1628.

[0116] The weight-average molecular weight (M) of at least one polyarylene ethersulfone polymer contained in the blend. W The weight-average molecular weight (M) is preferably in the range of 40,000 to 57,000 g / mol, preferably in the range of 41,000 to 56,000 g / mol, and more preferably in the range of 42,000 to 55,000 g / mol. W The ) is measured using gel permeation chromatography (GPC). This measurement is performed using gel permeation chromatography (GPC). Dimethylacetamide (DMAc) was used as the solvent, and a narrow distribution of polymethyl methacrylate was used as the measurement standard.

[0117] In a preferred embodiment, the first film (F1) comprises at least one polyarylene ethersulfone polymer selected from the group consisting of polysulfone (PSU), polyethersulfone (PESU), and polybiphenylsulfone (PPSU).

[0118] In a particularly preferred embodiment, the polyarylene ethersulfone polymer contained in the first film (F1) is polyethersulfone (PESU).

[0119] Furthermore, the first film (F1) comprises at least one further polymer. In this specification, "at least one further polymer" means just one further polymer, and also a mixture of two or more further polymers. Preferably, the first film comprises one further polymer.

[0120] Suitable additional polymers are selected from the group consisting of, for example, phenoxy polymers, polyethylene oxide polymers, and polyvinylpyrrolidone polymers.

[0121] Phenoxy® is a commercially available polymer containing hydroxyl groups. The structural formula of Phenoxy® PKHH is given by the following formula II). [ka]

[0122] In formula II, n' is an integer preferably in the range of 10 to 100, preferably in the range of 15 to 90, and more preferably in the range of 20 to 80.

[0123] Phenoxy polymers can be prepared by reacting bisphenol A with epichlorohydrin.

[0124] Preferably, a phenoxy polymer having a Tg in the range of 70 to 100°C, more preferably in the range of 80 to 98°C, and particularly preferably in the range of 85 to 98°C is used. The glass transition temperature Tg is determined by DSC measurement according to ISO 11357-1 using a heating rate of 10 K / min.

[0125] A suitable phenoxy polymer has a number-average molecular weight in the range of 2500 to 25000 g / mol, preferably in the range of 5000 to 20000 g / mol. The number-average molecular weight is determined as follows for the polyarylene ethersulfone polymer contained in the upper surface layer (UTL).

[0126] Preferably, Phenoxy PKHH having a Tg of 97°C is used. The Phenoxy PKHH content in these blends is 2 to 40% by weight based on the total weight of the film (F1 / F2).

[0127] Polyethylene oxide can be used as a further polymer to lower the Tg of the polyarylene ethersulfone polymer. Based on molecular weight, the polyethylene oxide is either liquid or solid. Polyethylene oxide having a number average molecular weight of 200 to 40,000 g / mol can be used. Preferably, polyethylene oxide having a number average molecular weight of 600 to 8,000 g / mol is used. The polyethylene oxide content in these blends contained in the first film (F1) and / or the second film (F2) is 2 to 40% by weight based on the total weight of the films (F1 / F2).

[0128] Block copolymers of polyarylene ethersulfone and polyethylene oxide can also be used as materials for films (F1 / F2). Possible preparations of block copolymers are described in European Patent No. 2739668 and European Patent No. 2992038.

[0129] Furthermore, a blend of polyarylene ethersulfone polymer and polyvinylpyrrolidone (PVP) can be used. To maintain good processability, PVP having a number-average molecular weight of 5,000 to 50,000 g / mol is preferred. The PVP content in these blends (F1 / F2) is 2 to 40% by weight based on the total weight of the film (F1 / F2).

[0130] In a preferred embodiment, the blend of the first film (F1) comprises, based on the total weight of the first film (F1), 97.5 to 65% by weight of at least one polyarylene ethersulfone polymer and 2.5 to 35% by weight of at least one further polymer.

[0131] In a more preferred embodiment, the blend of the first film (F1) comprises, based on the total weight of the first film (F1), 97 to 70% by weight of at least one polyarylene ethersulfone polymer and 3 to 30% by weight of at least one further polymer.

[0132] In a particularly preferred embodiment, the blend of the first film (F1) comprises, based on the total weight of the first film (F1), 96 to 72% by weight of at least one polyarylene ethersulfone polymer and 4 to 28% by weight of at least one further polymer.

[0133] The preparation of the first film (F1) is known to those skilled in the art. The first film (F1) can be prepared, for example, by film extrusion of the blend contained in the first film (F1). Details relating to film extrusion are known in the art, for example, from C. Rauwendaal, "Polymer Extrusion," Hanser, 5th edition 2014.

[0134] The first film (F1) and the second film (F2) included in the sandwich panel preferably have a thickness in the range of 0.02 to 0.15 mm, independently of each other. In a preferred embodiment, the first film (F1) and the second film (F2) included in the sandwich panel preferably have the same thickness in the range of 0.02 to 0.15 mm.

[0135] The first film (F1) and the second film (F2) contained in the sandwich panel preferably independently of each other have a density of 1.15 to 1.36 g / cm³. 3 It has a density within the range of . In a preferred embodiment, the first film (F1) and the second film (F2) contained in the sandwich panel are preferably 1.16 to 1.35 g / cm³ 3 They have the same density within the range.

[0136] In another preferred embodiment, the first film (F1) and the second film (F2) contained in the sandwich panel contain the same polyarylene ethersulfone polymer.

[0137] In another preferred embodiment, the first film (F1) and the second film (F2) contained in the sandwich panel contain the same polyarylene ethersulfone polymer and the same further polymer. In another preferred embodiment, the first film (F1) and the second film (F2) contained in the sandwich panel contain the same polyarylene ethersulfone polymer, the same further polymer, and have the same thickness. In another preferred embodiment, the first film (F1) and the second film (F2) contained in the sandwich panel contain the same polyarylene ethersulfone polymer, the same further polymer, have the same thickness, and have the same density.

[0138] In another preferred embodiment, the blend contained in the first film (F1) and the blend contained in the second film (F2) in the sandwich panel contain the same polyarylene ethersulfone polymer, the same further polymer, have the same thickness, have the same density, and have the same glass transition temperature Tg.

[0139] In a particularly preferred embodiment, the first film (F1) and the second film (F2) are identical.

[0140] Preferably, the blend contained in the first film (F1) has a glass transition temperature Tg at least 5K lower than the glass transition temperature Tg of the at least one polyarylene ethersulfone polymer contained in the upper surface layer (UTL) and the glass transition temperature Tg of the at least one polyarylene ethersulfone polymer contained in the foam core layer (FCL). The glass transition temperature Tg is determined as described above.

[0141] Therefore, another object of the present invention is a sandwich panel in which the blend contained in the first film (F1) has a glass transition temperature Tg at least 5K lower than the glass transition temperature Tg of the at least one polyarylene ethersulfone polymer contained in the upper surface layer (UTL) and the glass transition temperature Tg of the at least one polyarylene ethersulfone polymer contained in the foam core layer (FCL).

[0142] More preferably, the blend contained in the first film (F1) has a glass transition temperature Tg at least 5K lower than the glass transition temperature Tg of the at least one polyarylene ethersulfone polymer contained in the upper surface layer (UTL), the glass transition temperature Tg of the at least one polyarylene ethersulfone polymer contained in the foam core layer (FCL), and the glass transition temperature Tg of the lower surface layer (LTL).

[0143] If the blend contained in the first film (F1) has two or more glass transition temperatures Tg, the higher glass transition temperature Tg is used as the reference.

[0144] The same descriptions, explanations, and preferred features described above for the first film (F1) apply equally to the second film (F2).

[0145] The second film (F2) comprises at least one polyarylene ethersulfone and at least one further polymer. In this specification, "at least one polyarylene ethersulfone polymer" means just one polyarylene ethersulfone polymer and also a mixture of two or more different polyarylene ethersulfone polymers. Preferably, the second film (F2) comprises one polyarylene ethersulfone polymer.

[0146] With respect to at least one polyarylene ethersulfone polymer contained in the second film (F2), the above descriptions, explanations, and preferred features relating to polyarylene ethersulfone polymers also apply.

[0147] In a preferred embodiment, the second film (F2) comprises at least one polyarylene ethersulfone polymer selected from the group consisting of polysulfone (PSU), polyethersulfone (PESU), and polybiphenylsulfone (PPSU).

[0148] In a particularly preferred embodiment, the polyarylene ethersulfone polymer contained in the second film (F2) is polyethersulfone (PESU).

[0149] Furthermore, the second film (F2) comprises at least one further polymer. In this specification, "at least one further polymer" means just one further polymer, and also a mixture of two or more further polymers. Preferably, the first film comprises one further polymer.

[0150] Suitable additional polymers are selected from the group consisting of, for example, phenoxy polymers, polyethylene oxide polymers, and polyvinylpyrrolidone polymers.

[0151] Phenoxy® is a commercially available polymer containing hydroxyl groups. The structural formula of Phenoxy® PKHH is given by the following formula II). [ka]

[0152] Preferably, Phenoxy PKHH having a Tg of 97°C is used. The Phenoxy PKHH content in these blends is 2 to 40% by weight based on the total weight of the film (F1 / F2).

[0153] Polyethylene oxide can be used as a further polymer to lower the Tg of the polyarylene ethersulfone polymer. Based on molecular weight, the polyethylene oxide is either liquid or solid. Polyethylene oxide having a number average molecular weight of 200 to 40,000 g / mol can be used. Preferably, polyethylene oxide having a number average molecular weight of 600 to 8,000 g / mol is used. The polyethylene oxide content in these blends contained in the first film (F1) and / or the second film (F2) is 2 to 40% by weight based on the total weight of the films (F1 / F2).

[0154] Block copolymers of polyarylene ethersulfone and polyethylene oxide can also be used as materials for films (F1 / F2). Possible preparations of block copolymers are described in European Patent No. 2739668 and European Patent No. 2992038.

[0155] Furthermore, a blend of polyarylene ethersulfone polymer and polyvinylpyrrolidone (PVP) can be used. To maintain good processability, PVP having a number-average molecular weight of 5,000 to 50,000 g / mol is preferred. The PVP content in these blends (F1 / F2) is 2 to 40% by weight based on the total weight of the film (F1 / F2).

[0156] In a preferred embodiment, the blend of the second film (F2) comprises, based on the total weight of the second film (F2), 97.5 to 65% by weight of at least one polyarylene ethersulfone polymer and 2.5 to 35% by weight of at least one further polymer.

[0157] In a more preferred embodiment, the blend of the second film (F2) comprises, based on the total weight of the second film (F2), 97 to 70% by weight of at least one polyarylene ethersulfone polymer and 3 to 30% by weight of at least one further polymer.

[0158] In a particularly preferred embodiment, the blend of the second film (F2) comprises, based on the total weight of the second film (F2), 96 to 72% by weight of at least one polyarylene ethersulfone polymer and 4 to 28% by weight of at least one further polymer.

[0159] The preparation of the second film (F2) is known to those skilled in the art. The second film (F2) can be prepared, for example, as described above for the first film.

[0160] Preferably, the blend contained in the second film (F2) has a glass transition temperature Tg at least 5K lower than the glass transition temperature Tg of the at least one polyarylene ethersulfone polymer contained in the upper surface layer (UTL) and the glass transition temperature Tg of the at least one polyarylene ethersulfone polymer contained in the foam core layer (FCL). The glass transition temperature Tg is determined as described above.

[0161] Therefore, another object of the present invention is a sandwich panel in which the blend contained in the second film (F2) has a glass transition temperature Tg at least 5K lower than the glass transition temperature Tg of the at least one polyarylene ethersulfone polymer contained in the lower surface layer (LTL) and the glass transition temperature Tg of the at least one polyarylene ethersulfone polymer contained in the foam core layer (FCL).

[0162] More preferably, the blend contained in the second film (F2) has a glass transition temperature Tg at least 5K lower than the glass transition temperature Tg of the at least one polyarylene ethersulfone polymer contained in the upper surface layer (UTL), the glass transition temperature Tg of the at least one polyarylene ethersulfone polymer contained in the foam core layer (FCL), and the glass transition temperature of the lower surface layer (LTL).

[0163] If the blend contained in the second film (F2) has two or more glass transition temperatures Tg, the higher glass transition temperature Tg is used as the reference.

[0164] Sandwich panel The sandwich panel preferably has a thickness in the range of 1.0 to 51.3 mm.

[0165] Therefore, another object of the present invention is a sandwich panel having a thickness in the range of 1.0 to 51.3 mm.

[0166] The sandwich panel consists of layers in the following order, starting with the upper surface layer (UTL): upper surface layer (UTL), first film (F1), foam core layer (FCL), second film (F2), and lower surface layer (OTL).

[0167] In a preferred embodiment, the sandwich panel contains at least 80% by weight, more preferably at least 85% by weight, and particularly preferably at least 90% by weight of at least one polyarylene ethersulfone polymer, based on the total weight of the polymers in the sandwich panel.

[0168] In another preferred embodiment, the sandwich panel comprises only one polyarylene ethersulfone polymer. In a more preferred embodiment, the sandwich panel comprises only one polyarylene ethersulfone polymer, which is selected from the group consisting of polysulfone (PSU), polyethersulfone (PESU), and polybiphenylsulfone (PPSU).

[0169] In a particularly preferred embodiment, the sandwich panel comprises only one type of polyarylene ethersulfone polymer, the polyarylene ethersulfone polymer being polyethersulfone (PESU).

[0170] Accordingly, another object of the present invention is a sandwich panel in which at least one further polymer contained in the blend of the first film (F1) and at least one further polymer contained in the second film (F2) are, independently of each other, at least one polymer selected from the group consisting of phenoxy polymers, polyethylene oxide polymers, and polyvinylpyrrolidone polymers.

[0171] Therefore, another object of the present invention is a sandwich panel in which at least one polyarylene ethersulfone polymer contained in the upper surface layer (UTL), at least one polyarylene ethersulfone polymer contained in the foam core layer (FCL), at least one polyarylene ethersulfone polymer contained in the lower surface layer (LTL), at least one polyarylene ethersulfone polymer contained in the first film (F1), and at least one polyarylene ethersulfone polymer contained in the second film (F2) are independently at least one polymer selected from the group consisting of polysulfone (PSU), polyethersulfone (PESU), and polybiphenylsulfone (PPSU).

[0172] Therefore, another object of the present invention is a sandwich panel in which the upper surface layer (UTL), foam core layer (FCL), lower surface layer (LTL), first film (F1), and second film (F2) each contain the same polyarylene ethersulfone polymer.

[0173] Process for manufacturing sandwich panels Another objective of the present invention is, i) A step of preparing an upper surface layer (UTL) comprising at least one polyarylene ethersulfone polymer and at least one fiber reinforcing material, a foam core layer (FCL) comprising at least one polyarylene ethersulfone polymer, and a lower surface layer (LTL) comprising at least one polyarylene ethersulfone polymer and at least one fiber reinforcing material, ii) A step of placing a first film (F1) comprising a blend of at least one polyarylene ethersulfone polymer and at least one further polymer between the upper surface layer (UTL) and the foam core layer (FCL), iii) A step of obtaining a sandwich comprising layers in the following order, starting from the upper surface layer (UTL): upper surface layer (UTL), first film (F1), foam core layer (FCL), second film (F2), and lower surface layer (LTL), by placing a second film (F2) comprising a blend of at least one polyarylene ethersulfone polymer and at least one further polymer between the lower surface layer (LTL) and the foam core layer (FLC), iv) A step of heating the sandwich obtained in step iii) to a temperature up to 1K lower than the glass transition temperature Tg of at least one polyarylene ethersulfone polymer contained in the upper surface layer (UTL), the glass transition temperature Tg of at least one polyarylene ethersulfone polymer contained in the foam core layer (FCL), and the glass transition temperature Tg of the lower surface layer (LTL). This is a process for manufacturing sandwich panels according to the present invention, including the process described herein.

[0174] Steps i) to iii) can be performed in any order. Preferably, steps i) to iii) are performed simultaneously. Heating of individual layers by IR radiation before assembly to the panel is also possible.

[0175] In a preferred embodiment, in step iv), the sandwich obtained in step iii) is heated to a temperature lower than the glass transition temperature Tg of at least one polyarylene ethersulfone polymer contained in the upper surface layer (UTL), the glass transition temperature Tg of at least one polyarylene ethersulfone polymer contained in the foam core layer (FCL), and the glass transition temperature Tg of the lower surface layer (LTL), in the range of 1 to 30 K, more preferably 5 to 25 K, and particularly preferably 10 to 20 K.

[0176] In another preferred embodiment, in step iv), a pressure in the range of 0.05 to 6 MPa is applied to the upper surface layer (UTL) and lower surface layer (LTL) of the sandwich obtained in step iii).

[0177] In preferred embodiments, the sandwich panels according to the present invention are used as building components for the aerospace industry or for constructing rotor blades for wind turbines.

[0178] In a particularly preferred embodiment, the sandwich panel according to the present invention is used as interior trim for an aircraft cabin.

[0179] In another preferred embodiment, the sandwich panel according to the present invention is used in an aircraft as an interior component, preferably an overhead storage compartment, floor panel, roof panel, side panel, and cabin wall.

[0180] The sandwich panel according to the present invention can be reused after the first use is completed. Therefore, another object of this application is a process for reusing the sandwich panel according to the present invention after the first use is completed. a) A process of crushing the sandwich panel to obtain crushed material, b) A process to manufacture a new product using the crushed material obtained in step a) It is a process that includes [this].

[0181] The crushing in step a) can be carried out by grinding and / or milling. The product produced in step b) is preferably a fiber-reinforced polyarylene ethersulfone polymer compound.

[0182] The present invention is not limited thereto and will be described in more detail by the following embodiments.

[0183] Ingredients used: Foam core layer (FCL): A 20mm thick polyethersulfone (PESU)-based foam, Divinycell F50, was used as the foam core. The Tg of the foam was measured by DSC at 225°C (FCL).

[0184] Upper surface layer (UTL) / lower surface layer (LTL): The upper surface layer (UTL) and lower surface layer (LTL) of this invention are 460 g / m². 2 Area weight and 155 g / m² 2 A polyethersulfone (PESU) coated glass fiber fabric having the polymer content was used (UTL / LTL_inv).

[0185] For comparison, the upper surface layer (UTL) and lower surface layer (LTL) are 450 g / m². 2 Area weight and 150g / m² 2 A polyetherimide (PEI) coated glass fiber fabric having the polymer content was used (UTL / LTL_comp).

[0186] First film (F1) / Second film (F2) For comparison, a first film (F1) and a second film (F2) were used, both extruded from polyetherimide Ultem D1010, with a Tg of 217°C and a thickness of 98 μm (F1 / F2_comp).

[0187] As the first film (F1) and second film (F2) of the present invention, films extruded from polyethersulfone (PESU) Ultrason E 1010 / Phenoxy PKH 65 / 35 blend, having a Tg1 of 94°C and a Tg2 of 218°C, and a thickness of 101 μm, were applied (F1 / F2_inv1).

[0188] As second comparative films (F1) and (F2), films extruded from polyethersulfone (PESU) Ultrason E 1010, with a Tg of 224°C and a thickness of 97 μm, were used (F1 / F2_comp2).

[0189] As the first film (F1) and second film (F2) of the present invention, films extruded from polyethersulfone (PESU) Ultrason E 1010 / Pluriol 6000 95 / 5-blend, having a Tg of 195°C and a thickness of 102 μm, were applied (F1 / F2_inv2).

[0190] The sandwich panels were prepared by laminating a foam core layer (FCL) between two film layers (F1 and F2), as well as an upper surface layer (UTL) and a lower surface layer (LTL), for 20 minutes in a heated press at 230°C.

[0191] Next, the resulting sandwich panels were visually evaluated, and those without adhesion between the surface layer and the foam core were selected.

[0192] The remaining sandwich panels were tested using a three-point bending test. The fractured sandwich panels were evaluated for interlayer adhesion (adhesive failure / cohesive failure). The results are summarized in Table 1.

[0193] [Table 1]

[0194] Several sandwich panels (60cm x 40cm in size) of each composition were formed and then ground in a mill equipped with a sieving unit to obtain particles smaller than 5mm in size. These materials were then characterized by their glass fiber content (char yield, wt%) and subsequently compounded with PESU (Ultrason E 1010) in a ZSK 18 twin-screw extruder to obtain a product with a fiber content of 10 wt% (corresponding to product M in Table 2). The melting temperature during compounding was 365°C, and the throughput was 6 kg / h at a screw speed of 250 rpm.

[0195] Next, the obtained granular material was molded into ISO bars for Charpy impact testing (ISO 179 1eU) and samples for tensile testing (ISO 527) at a melting temperature of 360°C and a tool temperature of 150°C. The test results are summarized in Table 2.

[0196] [Table 2]

[0197] Sandwich panels with a PESU content exceeding 80% by weight relative to the total polymer content result in fiber-reinforced thermoplastic materials with good toughness and strength.

Claims

1. An upper surface layer (UTL) comprising at least one polyarylene ethersulfone polymer and at least one fiber reinforcing material, A foam core layer (FCL) containing at least one type of polyarylene ethersulfone polymer, A lower surface layer (LTL) comprising at least one polyarylene ethersulfone polymer and at least one fiber reinforcing material Includes, The upper surface layer (UTL) is bonded to the foam core layer (FCL) via a first film (F1) comprising a blend of at least one polyarylene ethersulfone polymer and at least one further polymer. The lower surface layer (LTL) is bonded to the foam core layer (FCL) via a second film (F2) comprising a blend of at least one polyarylene ethersulfone polymer and at least one further polymer. Sandwich panel.

2. The sandwich panel according to claim 1, wherein the blend contained in the first film (F1) has a glass transition temperature Tg at least 5 K lower than the glass transition temperature Tg of the at least one polyarylene ethersulfone polymer contained in the upper surface layer (UTL) and the glass transition temperature Tg of the at least one polyarylene ethersulfone polymer contained in the foam core layer (FCL).

3. The sandwich panel according to claim 1 or 2, wherein the blend contained in the second film (F2) has a glass transition temperature Tg at least 5 K lower than the glass transition temperature Tg of the at least one polyarylene ethersulfone polymer contained in the lower surface layer (LTL) and the glass transition temperature Tg of the at least one polyarylene ethersulfone polymer contained in the foam core layer (FCL).

4. The sandwich panel according to any one of claims 1 to 3, wherein the at least one further polymer contained in the blend of the first film (F1) and the at least one further polymer contained in the second film (F2) are, independently of each other, at least one polymer selected from the group consisting of phenoxy polymer, polyethylene oxide polymer, and polyvinylpyrrolidone polymer.

5. The at least one polyarylene ethersulfone polymer contained in the upper surface layer (UTL), the at least one polyarylene ethersulfone polymer contained in the foam core layer (FCL), the at least one polyarylene ethersulfone polymer contained in the lower surface layer (LTL), the at least one polyarylene ethersulfone polymer contained in the first film (F1), and the at least one polyarylene ethersulfone polymer contained in the second film (F2) are each independently of each other as components, (A1) At least one dihalogen compound selected from the group consisting of 4,4'-dichlorodiphenylsulfone and 4,4'-difluorodiphenylsulfone is added to the reaction mixture (R Ｇ ) containing 80% by weight or more of component (A1) in the dihalogen component, (B1) At least one dihydroxy compound selected from the group consisting of 4,4'-dihydroxy-diphenylsulfone, bisphenol A, 4,4'-dihydroxybiphenyl, and hydroquinone is added to the reaction mixture (R Ｇ ) containing 80% by weight or more of the dihydroxy component based on the total weight of component (B1) in ) Reaction mixture containing (R Ｇ The sandwich panel according to any one of claims 1 to 4, wherein the sandwich panel is at least one polymer obtained by converting ).

6. The sandwich panel according to any one of claims 1 to 5, wherein the at least one polyarylene ethersulfone polymer contained in the upper surface layer (UTL), the at least one polyarylene ethersulfone polymer contained in the foam core layer (FCL), the at least one polyarylene ethersulfone polymer contained in the lower surface layer (LTL), the at least one polyarylene ethersulfone polymer contained in the first film (F1), and the at least one polyarylene ethersulfone polymer contained in the second film (F2) are each at least one polymer independently selected from the group consisting of polysulfone (PSU), polyethersulfone (PESU), and polybiphenylsulfone (PPSU).

7. The sandwich panel according to any one of claims 1 to 6, wherein the upper surface layer (UTL), the foam core layer (FCL), the lower surface layer (LTL), the first film (F1), and the second film (F2) each contain the same polyarylene ethersulfone polymer.

8. A sandwich panel according to any one of claims 1 to 7, having a thickness in the range of 1.0 to 51.3 mm.

9. The sandwich panel according to any one of claims 1 to 8, wherein the foam core layer (FCL) has a thickness in the range of 0.76 to 50 mm.

10. The sandwich panel according to any one of claims 1 to 9, wherein the upper surface layer (UTL) and the lower surface layer (LTL) independently have a thickness in the range of 0.1 to 0.5 mm.

11. The sandwich panel according to any one of claims 1 to 10, wherein the first film (F1) and the second film (F2) independently have a thickness in the range of 0.02 to 0.15 mm.

12. The foam core layer (FCL) has a density of 25 to 200 kg / m³. ３ A sandwich panel according to any one of claims 1 to 11, having a density within the range.

13. i) A step of preparing the upper surface layer (UTL) comprising at least one polyarylene ethersulfone polymer and at least one fiber reinforcing material, the foam core layer (FCL) comprising at least one polyarylene ethersulfone polymer, and the lower surface layer (LTL) comprising at least one polyarylene ethersulfone polymer and at least one fiber reinforcing material, ii) A step of placing the first film (F1), which comprises a blend of at least one polyarylene ethersulfone polymer and at least one further polymer, between the upper surface layer (UTL) and the foam core layer (FCL), iii) A step of obtaining a sandwich comprising a second film (F2) comprising a blend of at least one polyarylene ethersulfone polymer and at least one further polymer, placed between the lower surface layer (LTL) and the foam core layer (FCL), starting from the upper surface layer (UTL), in the order of upper surface layer (UTL), first film (F1), foam core layer (FCL), second film (F2), and lower surface layer (LTL), iv) A step of heating the sandwich obtained in step iii) to a temperature up to 1 K lower than the glass transition temperature Tg of the at least one polyarylene ethersulfone polymer contained in the upper surface layer (UTL), the glass transition temperature Tg of the at least one polyarylene ethersulfone polymer contained in the foam core layer (FCL), and the glass transition temperature Tg of the lower surface layer (LTL). A method for manufacturing a sandwich panel according to any one of claims 1 to 12, including the method described in any one of claims 1 to 12.

14. A sandwich panel obtained by the method described in claim 13.

15. Use of the sandwich panel according to any one of claims 1 to 12 and 14 as a building component for the aerospace industry or for the construction of rotor blades for wind turbines.

16. A method for reusing a sandwich panel according to any one of claims 1 to 12 and 14 at the end of its first use, a) A step of crushing the sandwich panel to obtain crushed material, b) A process of manufacturing a new product using the pulverized material obtained in step a) Methods that include...

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