An improved sandwich panel
A sequential hot-pressing method for bonding pre-formed thermoplastic skins to a foam core addresses the limitations of existing thermoplastics-based panels by achieving improved mechanical properties and core thickness, ensuring efficient production and recyclability for aviation applications.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SABANCI UNIVERSITY
- Filing Date
- 2025-01-27
- Publication Date
- 2026-07-23
AI Technical Summary
Existing thermoplastics-based sandwich panels for aviation face challenges with low mechanical properties, limited thickness, and lengthy production times, particularly in achieving a high core-to-total thickness ratio and efficient recyclability.
A method involving a sequential hot-pressing process to bond pre-formed thermoplastic skins with a foam core, using a single heated plate to fuse the skins to the core, allowing for a thicker core and improved mechanical properties while maintaining lightweight characteristics.
The method enables sandwich panels with enhanced mechanical properties, increased core thickness, and reduced production duration, while maintaining recyclability and cost-effectiveness, suitable for aviation applications.
Smart Images
Figure TR2025050049_23072026_PF_FP_ABST
Abstract
Description
[0001] SPECIFICATION
[0002] AN IMPROVED SANDWICH PANEL
[0003] Technical Field
[0004] The present application relates to sandwich panels for use in aviation. The present application further relates to a method for production of recyclable composite sandwich panels that enable enhanced flexibility in thickness design and improved mechanical properties.
[0005] Background
[0006] In the aviation industry, sandwich panels are extensively used in applications that require a balance of high structural rigidity and low weight. Recent research has increasingly focused on prioritizing thermoplastic materials over thermosets for the production of sandwich panels, as thermoplastics offer significant advantages in terms of recyclability, including easier reprocessing, reduced energy consumption, and higher production volumes. While efforts have been made to achieve these goals, challenges remain, such as low mechanical properties, reduced extent of available thickness, and lengthy production times.
[0007] Accordingly, it is still desired to develop new robust processing and manufacturing methods for thermoplastics-based sandwich structures that meet the stringent requirements of the aerospace industry by involving a short-duration hot-press applied from the lower side mechanism.
[0008] Summary
[0009] The primary object of the present application is to overcome the above-mentioned shortcomings of the prior art. Another object of the present application is to propose recyclable assemblies and sandwich panels for use in aviation, and methods that enable the same. A further object of the present application is to propose recyclable assemblies and sandwich panels with improved mechanical properties, and an increased foam core thickness, which are obtainable with decreased production durations with low production and investment costs. The present disclosure achieves this object with the features that constitute the appended independent claims.
[0010] Brief Description of the Drawings
[0011] The proposed approach will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which:
[0012] Fig. 1 illustrates a close-up perspective section view of a sandwich panel according to the present application, for use in aviation.
[0013] Fig. 2 illustrates an exploded side view showing a foam core along with the first skin and second skin which are aligned with the foam core at a first side and second side thereof, respectively; prior to the production of the sandwich panel of Fig. 1.
[0014] Fig.3 illustrates a side view showing preparation to a first hot-pressing step for bonding a first skin onto a first side of the foam core, in accordance with a first possible version of the proposed method.
[0015] Fig.4 illustrates a side view based on Fig.3, upon completion of the first hot-pressing step.Fig. 5 illustrates a side view showing preparation to an exemplary second hot-pressing step for bonding a second skin layer onto a second side of the core opposite to the first side, in accordance with the first possible version of the proposed method.
[0016] Fig. 6 illustrates a side view based on Fig.5, upon completion of the second hot-pressing step.
[0017] Fig. 7 illustrates a side view showing preparation to a first hot-pressing step for bonding a first skin onto a first side of the foam core, in accordance with a second possible version of the proposed method.
[0018] Fig. 8 illustrates a side view based on Fig. 7, upon completion of the first hot-pressing step.
[0019] Fig. 9 illustrates a side view showing preparation to an exemplary second hot-pressing step for bonding a second skin layer onto a second side of the core opposite to the first side, in accordance with the second possible version of the proposed method.
[0020] Fig. 10 illustrates a side view based on Fig.9, upon completion of the second hot-pressing step.
[0021] Fig. 11 illustrates a side view showing preparation to a first hot-pressing step for bonding a first skin onto a first side of the foam core, in accordance with a third possible version of the proposed method.
[0022] Fig. 12 illustrates a side view based on Fig. 11, upon completion of the first hot-pressing step.
[0023] Fig. 13 illustrates a side view showing preparation to an exemplary second hot-pressing step for bonding a second skin layer onto a second side of the core opposite to the first side, in accordance with the third possible version of the proposed method.
[0024] Fig. 14 illustrates a side view based on Fig. 13, upon completion of the second hot-pressing step.
[0025] Fig. 15 illustrates a side view showing preparation to a first hot-pressing step for bonding a first skin onto a first side of the foam core, in accordance with a fourth possible version of the proposed method.
[0026] Fig. 16 illustrates a side view based on Fig. 15, upon completion of the first hot-pressing step.
[0027] Fig. 17 illustrates a side view showing preparation to an exemplary second hot-pressing step for bonding a second skin layer onto a second side of the core opposite to the first side, in accordance with the fourth possible version of the proposed method.
[0028] Fig. 18 illustrates a side view based on Fig. 17, upon completion of the second hot-pressing step.
[0029] Detailed Description
[0030] The present disclosure proposes a sandwich panel (100) for interior use in aviation. The term "sandwich panel" can be also referred to as panel (100) throughout the present specification.
[0031] With reference to Fig. 1, the proposed panel (100) comprises a core (75) which is sandwiched in-between a first skin layer (83) and a second skin layer (84). The core (75) is in the form of a foam which is formed from one or more thermoplastics and the one or both of the first skin layer (83) and second skin layer (84) comprise one or more thermoplastics in which one or more reinforcement materials are embedded (e.g., glass and / or carbon fibers, among others).With reference to Fig. 2 in conjunction with Fig. 1, the panel (100) is obtainable by the method proposed with the present application. The panel (100) is formed from at least the following components:
[0032] a pre-formed first skin (81) and a pre-formed second skin (82) both comprising one or more of the thermoplastics in which one or more of the reinforcement materials are embedded, respectively forming the first skin layer (83) and the second skin layer (84), and
[0033] a pre-formed foam core (70) forming the core (72) and comprising one or more of the thermoplastics, sandwiched in-between the first skin (81) and second skin (82); such that, upon implementation of the proposed method,
[0034] o a first interlayer (91) is formed by fusion of the one or more thermoplastics at a first side (71) of the foam core (70), sandwiched in-between the resulting core (75) and first skin layer (83); and o a second interlayer (92) is formed by fusion of the one or more thermoplastics at a second side (72) of the foam core (70), sandwiched in-between the resulting core (75) and first skin layer (83).
[0035] That the panel (100) is obtained by the method proposed with the present application is optically observable from a cross-section thereof, in accordance with the following aspects:
[0036] reinforcement of the first skin layer (83) and second skin layer (84) is not achieved by merely placing the one or more reinforcement materials onto a plate and embedding the same into one or more thermoplastics by a hot-pressing; hence, it is observable that a more uniform and / or greater extent of embedding of the reinforcement material into the thermoplastics is achievable by pre-forming the first skin layer (83) and second skin layer (84);
[0037] the first skin layer (83) and second skin layer (84) are not obtained by merely fusing the first side (71) and second side (72) of the foam core (70) by directly hot-pressing the same; hence the relatively high uniformity and / or extent of embedding of the reinforcement material is easily observable as discussed above.
[0038] When compared to prior art panels that are obtained by heating side surfaces of foam cores with or without placing reinforcement materials in-between heated plates (e.g., by hot-pressing);
[0039] with reference to Fig. 1, the proposed method enables a higher Tc:T ratio between a core thickness (Tc) and a total thickness of the panel (100) perpendicular to a plane (P) defined by the panel (100); considering that better mechanical properties in terms of three-point bending tests are substantially available with (higher) foam core thicknesses (Tc), and total thickness (T) requirements that apply in aviation industry for sandwich panels which are employed in interior components' design are strict, it is hereby considered desirable to achieve a higher Tc:T ratio for achieving improved three-point bending test results. The proposed method enables that a resulting panel (100) has a greater Tc:T value by enabling a thicker core (75) when compared to the panel (100) that can have an allowable extent of total thickness.
[0040] The proportion of the core (75) is thus increased in the panel (100). Considering that a density of the core (75) which is in the form of a foam would inherently be lower than an overall density of the panel (100), the present disclosure enables a decreased (thus, enhanced) overall density to the panel (100), thereby enabling a relatively lightweight panel (100).The proposed panel (100) is enabled by implementation of any possible variation of the method disclosed in the present specification. Any variation of the proposed method comprises the following steps for production of an assembly (90) that can be used as a separator in aviation interior components, or as an intermediary product to the panel (100):
[0041] step-I) provision of a thermoplastic foam core (70); provision of a thermoplastic first skin (81) in which one or more reinforcement materials is embedded; followed by
[0042] step-II) securing the first skin (81) onto the foam core (70), by the following sequential sub-steps:
[0043] (a) provision of an apparatus (1), comprising a first plate (10) and a second plate (20) opposing each other, arranged for approaching to one another in order to exert a pressure towards each other;
[0044] (b) arranging that, when the apparatus (1) is in use at an operation of hot-pressing of the first skin (81) with the foam core (70), only one of the first plate (10) or second plate (20) is provided with a first heat at the operation of hot-pressing of the first skin (81) with the foam core (70), to an extent which provides a first hot-pressing temperature for fusion at an interface between the first skin (81) with the foam core (70); (c) placing the foam core (70) and the first skin (81) which is not yet secured to the foam core (70), in-between the first plate (10) and second plate (20); such that the first skin (81) remains in-between the foam core (70) and the one of the first plate (10) or second plate (20) which is to be provided with said heat;
[0045] (d) conduction of the hot-pressing operation by provision of said first heat towards the foam core (70), through the first skin (81); thereby partially fusing the first skin (81) with the foam core (70) through a first interlayer (91) that is formed by said fusion; thus obtaining the assembly (90).
[0046] As a result, a respective first interlayer (91) is formed by the fusion between the foam core (75) and the first skin (81). It can be contemplated that a portion of the first skin (81) that is outside the first interlayer (91) forms a first skin layer (83).
[0047] It is hereby considered already important to obtain the assembly (90) for being used in preparation of the panel (100), upon further provision of the second skin (82). It can be contemplated that the assembly (90) has a second side (72) of the foam core (70) opposite to a first side (71) which is already provided with the first skin layer (83) that is formed from the first skin (81). The second side (72) of the foam core (70) in the assembly (90) is still porous, since it is not heated to the hot-pressing temperature during the step-II.
[0048] In the cases where a side of a separator to be used in aviation interior components is not exposed to conditions in which a porosity would constitute a problem, the assembly (90) can be already used as such separator without the provision of the second skin (82). For other cases, the porous second side (72) of the foam core (70) in the assembly (90) can be provided with a second skin layer (84), in order to obtain the panel (100) according to the present disclosure. In order to form the panel (100) from the assembly (90), the step-II can be considered as being followed by the step-III and step-IV below:
[0049] step-III) provision of a thermoplastic second skin (82) in which one or more reinforcement materials are embedded; followed by
[0050] step-IV) securing the second skin (82) onto the foam core (70), by the following sequential sub-steps:(e) arranging that, when the apparatus (1) is in use for an operation of hot-pressing of the first skin (81) with the foam core (70), only one of the first plate (10) or second plate (20) is provided with a second heat at the operation of hot-pressing of the second skin (82) with the foam core (70), to an extent which provides a second hot-pressing temperature for fusion at an interface between the second skin (82) with the foam core (70); the second heat can be equal to the first heat; the second hot-pressing temperature can be equal to the first hot-pressing temperature;
[0051] (f) placing the foam core (70) and the second skin (82) which is not yet secured to the foam core (70), inbetween the first plate (10) and second plate (20); such that the second skin (82) remains in-between the foam core (70) and the one of the first plate (10) or second plate (20) which is to be provided with said heat;
[0052] (g) conduction of the hot-pressing operation by provision of said second heat towards the foam core (70), through the second skin (82); thereby partially fusing the second skin (82) with the foam core (70) through a respective second interlayer (92) that is formed by said fusion; thus obtaining the panel (100).
[0053] As a result, a second interlayer (92) is formed by fusion between the foam core (75) and the second skin (82). It can be contemplated that a portion of the foam core (70) that is not fused during the hot-pressing operations forms the core (75); and a portion of the second skin (82) that is outside the second interlayer (92) forms the second skin layer (84).
[0054] In step-I, provision of the thermoplastic foam core (70) and thermoplastic first skin (81) can be respectively performed by
[0055] - preparation of the foam core (70) from one or more thermoplastics (here: PESU); and
[0056] - preparation of the first skin (81) by embedding one or more reinforcement materials into one or more thermoplastics (here: PESU reinforced with glass fibers).
[0057] In step-II, the apparatus (1) can be considered suitable for use in hot-pressing. In other words, the apparatus (1) can be considered as a hot-pressing device, or a hot-press.
[0058] For any version of the method, it can be considered that the step-(a) includes the arrangement of that, when the apparatus (1) is in use, the first plate (10) faces upwards in order to provide support to the components for formation of the assembly (90) or panel (100) against gravity. In other words, the apparatus (1) can be arranged such that, when in use, the first plate (10) is disposed below the second plate (20).
[0059] Regarding step-(a), it can be considered that the first plate (10) and second plate (10) are arranged to be horizontal and parallel to one another when the apparatus (1) is in use.
[0060] Regarding step-(b), the hot-pressing temperature can be considered within a range between a glass transition temperature and a melting temperature of the one or more thermoplastics of the foam core (70) and / or of the first skin (81). Likewise, regarding step-(e), the hot-pressing temperature can be considered within a range between a glass transition temperature and a melting temperature of the one or more thermoplastics of the foam core (70) and / or of one or both of the first skin (81) and second skin (82).
[0061] The step-(d) can be followed by cooling down the assembly (90). Likewise, the step-(g) can be followed by cooling down the panel (100). Preferably, the cooling operations are performed in a controlled, gradual fashion. Thisapproach facilitates a gradual cooling cycle, minimizing possible thermal gradients and preventing any sudden temperature changes; thereby enhancing the predictability of mechanical properties in the resulting assembly (90) or panel (100).
[0062] In step-III, the provision of the second skin (82) can be performed by preparation of the second skin (82) by embedding one or more reinforcement materials into one or more thermoplastics (here: PESU reinforced with glass fibers).
[0063] With reference to Fig. 3 and Fig. 4, in a first possible version of the method, the step-II comprises the following;
[0064] in step-(c), the first skin (81) is placed onto the first plate (10) and the foam core (70) is placed onto the first skin (81), such that a first side (71) of the foam core (70) contacts and covers the first skin (81); which can be followed by approaching the first plate (10) and second plate (20) to one another by moving at least one thereof by, for instance, a relative movement that is represented in Fig.3 with a bold dark arrow;
[0065] in step-(d), the first heat is provided from the first plate (10) towards the foam core (70), through the first skin (81), for implementing a fusion of the one or more thermoplastics at the first side (71) of the foam core (70); which can be followed by moving the first plate (10) and second plate (20) away from one another by moving at least one thereof by, for instance, a relative movement that is represented in Fig. with a bold dark arrow; the step-(d) is preferably followed by a cooling.
[0066] With reference to Fig. 5 and Fig. 6, in the first possible version of the method, the step-IV comprises the following;
[0067] in step-(f), the second skin (82) is placed onto the first plate (10) and the assembly (90) is placed onto the second skin (82) (that is, in a flapped fashion), such that a second side (72) of the foam core (70) that is opposite to the first side (71) contacts and covers the second skin (82); which can be followed by approaching the first plate (10) and second plate (20) to one another by moving at least one thereof by, for instance, a relative movement that is represented in Fig. 5 with a bold dark arrow;
[0068] in step-(g), the second heat is provided from the first plate (10) towards the foam core (70), through the second skin (82), for implementing a fusion of the one or more thermoplastics at the second side (72) of the foam core (70); which can be followed by moving the first plate (10) and second plate (20) away from one another by moving at least one thereof by, for instance, a relative movement that is represented in Fig.
[0069] 6 with a bold dark arrow; the step-(g) is preferably followed by a cooling.
[0070] In the first version, a low-cost and simple apparatus can be employed in which only the first plate is provided with a heater (30). Considering the weight of the foam core (70) or assembly (90), the respective steps (d) and (g) can involve the effect of such weight; reducing the necessity of the second plate (20), thereby enabling an even lower investment cost. Yet, for adding a pressure force onto the weight force of the foam core (70) or assembly (90) at respective steps (d) and (g), it can be considered that provision and use of the second plate (20) is preferable.
[0071] With reference to Fig. 7 and Fig. 8, in a second possible version of the method, the step-II comprises the following;
[0072] in step-(c), the foam core (70) is placed onto the first plate (10) and the first skin (81) is placed onto the foam core (70); such that the first skin (81) contacts and covers the first side (71) of the foam core (70);which can be followed by approaching the first plate (10) and second plate (20) to one another by moving at least one thereof by, for instance, a relative movement that is represented in Fig. 7 with a bold dark arrow;
[0073] in step-(d), the first heat is provided from the second plate (20) towards the foam core (70), through the first skin (81), for implementing a fusion of the one or more thermoplastics at the first side (71) of the foam core (70); which can be followed by moving the first plate (10) and second plate (20) away from one another by moving at least one thereof by, for instance, a relative movement that is represented in Fig. 8 with a bold dark arrow; the step-(d) is preferably followed by a cooling.
[0074] With reference to Fig. 9 and Fig. 10, in the second possible version of the method, the step-IV comprises the following;
[0075] in step-(f), the assembly (90) is placed onto the first plate (10) (in a flapped fashion) and the second skin (82) is placed onto the assembly (90), such that a second side (72) of the foam core (70) that is opposite to the first side (71) is contacted and covered by the second skin (82); which can be followed by approaching the first plate (10) and second plate (20) to one another by moving at least one thereof by, for instance, a relative movement that is represented in Fig. 9 with a bold dark arrow;
[0076] in step-(g), the second heat is provided from the second plate (20) towards the foam core (70), through the second skin (82), for implementing a fusion at the second side (72) of the foam core (70); which can be followed by moving the first plate (10) and second plate (20) away from one another by moving at least one thereof by, for instance, a relative movement that is represented in Fig.10 with a bold dark arrow; the step-(g) is preferably followed by a cooling.
[0077] In the second version, a low-cost and simple apparatus can be employed in which only the second plate is provided with a heater (30). Here, flapping of the assembly (90) is not necessary, minimizing the occurrence of possible labour-related errors.
[0078] With reference to Fig. 11 and Fig. 12, in a third possible version of the method, the step-II comprises the following;
[0079] in step-(b), the apparatus (1) arranged such that both of the first plate (10) and second plate (20) are arranged with respective heaters (30) for being energized independent from one another, such that the heating at hot-pressing operations through the first plate (10) and second plate (20) can be applied in a tandem or alternating fashion;
[0080] in step-(c), the first skin (81) is placed onto the first plate (10) and the foam core (70) is placed onto the first skin (81), such that a first side (71) of the foam core (70) contacts and covers the first skin (81); which can be followed by approaching the first plate (10) and second plate (20) to one another by moving at least one thereof by, for instance, a relative movement that is represented in Fig. 11 with a bold dark arrow; in step-(d), the first heat is provided from the first plate (10) towards the foam core (70), through the first skin (81), for implementing a fusion of the one or more thermoplastics at the first side (71) of the foam core (70); which can be followed by moving the first plate (10) and second plate (20) away from one another by moving at least one thereof by, for instance, a relative movement that is represented in Fig. 12 with a bold dark arrow; the step-(d) is preferably followed by a cooling.With reference to Fig. 13 and Fig. 14, in the third possible version of the method, the step-IV comprises the following;
[0081] in step-(f), the second skin (82) is placed onto the first plate (10) and the assembly (90) is placed onto the second skin (82) (that is, in a flapped fashion), such that a second side (72) of the foam core (70) that is opposite to the first side (71) contacts and covers the second skin (82); which can be followed by approaching the first plate (10) and second plate (20) to one another by moving at least one thereof by, for instance, a relative movement that is represented in Fig. 13 with a bold dark arrow;
[0082] in step-(g), the second heat is provided from the first plate (10) towards the foam core (70), through the second skin (82), for implementing a fusion of the one or more thermoplastics at the second side (72) of the foam core (70); which can be followed by moving the first plate (10) and second plate (20) away from one another by moving at least one thereof by, for instance, a relative movement that is represented in Fig.
[0083] 14 with a bold dark arrow; the step-(g) is preferably followed by a cooling.
[0084] With reference to Fig. 15 and Fig. 16, in a fourth possible version of the method, the step-II comprises the following;
[0085] in step-(b), as in the third version; the apparatus (1) arranged such that both of the first plate (10) and second plate (20) are arranged with respective heaters (30) for being energized independent from one another, such that the heating at hot-pressing operations through the first plate (10) and second plate (20) can be applied in a tandem or alternating fashion;
[0086] in step-(c), the foam core (70) is placed onto the first plate (10) and the first skin (81) is placed onto the foam core (70), such that a first side (71) of the foam core (70) is contacted and covered by the first skin (81); which can be followed by approaching the first plate (10) and second plate (20) to one another by moving at least one thereof by, for instance, a relative movement that is represented in Fig. 15 with a bold dark arrow;
[0087] in step-(d), the first heat is provided from the second plate (20) towards the foam core (70), through the first skin (81), for implementing a fusion of the one or more thermoplastics at the first side (71) of the foam core (70); which can be followed by moving the first plate (10) and second plate (20) away from one another by moving at least one thereof by, for instance, a relative movement that is represented in Fig. 16 with a bold arrow; the step-(d) is preferably followed by a cooling.
[0088] With reference to Fig. 17 and Fig. 18, in the fourth possible version of the method, the step-IV comprises the following;
[0089] in step-(f), the assembly (90) is placed onto the first plate (10) (in a flapped fashion) and the second skin (82) is placed onto the assembly (90), such that a second side (72) of the foam core (70) that is opposite to the first side (71) is contacted and covered by the second skin (82); which can be followed by approaching the first plate (10) and second plate (20) to one another by moving at least one thereof by, for instance, a relative movement that is represented in Fig. 17 with a bold dark arrow;
[0090] in step-(g), the second heat is provided from the second plate (20) towards the foam core (70), through the second skin (82), for implementing a fusion of the one or more thermoplastics at the second side (72) of the foam core (70); which can be followed by moving the first plate (10) and second plate (20) awayfrom one another by moving at least one thereof by, for instance, a relative movement that is represented in Fig. 18 with a bold dark arrow; the step-(g) is preferably followed by a cooling.
[0091] The hot-pressing that is applied in respective steps of the proposed method provides a robust bond at both sides of the core (75) with the first skin layer (83) and second skin layer (84), thereby enabling enhanced mechanical properties in every possible aspect that would apply to panels used in aviation interior components.
[0092] Distortion between resulting first skin layer (83) and second skin layer (84) is eliminated by forming the first skin layer (83) and second skin layer (84) one after another, instead of sandwiching the foam core (70) in-between the first skin (81) and second skin (82) at a single hot-pressing operation.
[0093] Bonding pre-formed first skin layer (83) and second skin layer (84) to the foam core (70) enables a design flexibility to the resulting first skin (81) and second skin (82), allows a thicker core (75) and thereby enabling the panel (100) to have improved mechanical properties.
[0094] The first and / or second hot-pressing temperature can be between the glass transition temperature and the melting temperature of the one or more thermoplastic building materials of the core (75).
[0095] In the appended Figs. 3-5, 7-9, 11-13 and 15-17, the first and second heats that are applied at respective hot-pressing operations are represented by dashed, bold arrows.
[0096] EXAMPLES:
[0097] Example 1:
[0098] The one or more thermoplastic material can comprise polyether sulfone (PESU), and the reinforcement material in the first skin (81) and second skin (82) (thus, the resulting first skin layer (83) and second skin layer (84)) can comprise glass fibers. Hence, the hot-pressing parameters can include a hot-pressing temperature within a range between 265-270°C , a short hot-pressing duration which can be 45 seconds or longer (e.g., 60s) and e.g., 0.4 tons of an applied pressure (per a plane (P) with 30cm x 30cm dimensions).
[0099] Subsequent hot-pressing operations provide interlayer(s) (91, 92) between the core (75) and respective skin layer(s) (83, 84), by softening and partial melting of the thermoplastic (e.g., PESU), thus enhances the bonding. A short duration such as 60 s provides relatively extended interlayer when compared to an even shorter duration 45 s; so, enhances the robustness, mechanical performance, suitability to high-stress applications. For the present example, thicknesses at interlayer(s) (91, 92) is greater for 270°C at 60 s when compared to 265°C with 45 s. Preferably, any heated one(s) of the first plate (10) and / or second plate (20) can be selected to have a thermal conductivity that is suitable to distribute heat rapidly and uniformly along the plane (P) (that is, through and along the plate (10 and / or 20) which is heated). The first plate (10) and / or second plate (20) can thus be metallic, e.g., steel.
[0100] The reinforcement material(s) in the pre-formed first skin (81) and / or second skin (82) can have a woven structure, or an unidirectional, cross ply or non-woven structure. In the case where the reinforcement material(s) have a woven structure, the woven structure can be selected from plain, twill and satin weave forms. The woven structure can preferably have a satin weave form.
[0101] With reference to Fig. 2, the foam core (70) had an exemplary initial foam core thickness (T3) of 6 mm, while exemplary first skin thickness (Tl) and second skin thickness (T2) were 0.2 mm; which amount to 6.4 mm priorto respective hot-pressing operations. The final, total thickness (T) of the sandwich panel (100) was 5.2 mm. Since the first skin (81) and second skin (82) for respectively forming the first skin layer (83) and second skin layer (84) are pre-formed, no dramatic decrease were observed in first skin thickness (Tl) and second skin thickness (T2) upon the respective hot-pressing operations. Since the present approach do not require formation of the first skin layer (83) and second skin layer (84) merely by fusion (in other words, melting) of the foam core (70), the foam core thickness (T3) is substantially maintained with a minimal extent of reduction, even after the respective hot-melting operations. Hence, the advantageous mechanical properties that are attributable to the hollow structure of the foam core (70) are substantially maintained substantially determine the mechanical properties of the resulting core (75), which are very close to those of the resulting assembly (70) or panel (100). Mechanical testing, including drum peel test, demonstrated no separation between the core (75) and the first skin layer (83) or second skin layer (84).
[0102] Mechanical testing, including three-point bending test, demonstrated an impressive flexural modulus of 3.2 GPa. Advanced imaging techniques, including computed tomography (CT) scans identified three distinct types of phases within the panel (100) structure: the core (75); a distinguishable skin structure which applies to both of the first skin layer (83) and second skin layer (84); and a distinguishable interlayer phase which applies to both of the first interlayer (91) and second interlayer (92).
[0103] These findings underscore the potential of utilizing thermoplastics in high-performance applications, such as aircraft interiors, where lightweight, durable, and thermally efficient materials are useful.Reference signs:
[0104] 1 apparatus
[0105] 10 first plate
[0106] 11 contact side of the first plate 20 second plate
[0107] 21 contact side of the second plate 30 heater
[0108] 70 foam core
[0109] 71 first side
[0110] 72 second side
[0111] 75 core
[0112] 81 first skin
[0113] 82 second skin
[0114] 83 first skin layer
[0115] 84 second skin layer
[0116] 90 assembly
[0117] 91 first interlayer
[0118] 92 second interlayer
[0119] 100 panel
[0120] P plane
[0121] T total thickness
[0122] T1 first skin thickness
[0123] T2 second skin thickness
[0124] T3 foam core thickness
[0125] Tc core thickness
Claims
Claims1. An assembly (90) for use as a separator in aviation interiors; the assembly (90) comprising a first skin layer (83) bonded onto a first side (71) of a foam core (70); wherein the first skin layer (83) comprises one or more thermoplastics in which one or more reinforcement materials are embedded, the foam core (70) is formed from the one or more thermoplastics, the assembly (90) comprises a first interlayer (91) in-between the first skin layer (83) and the foam core (70) formed by fusion of the one or more thermoplastics at the first side (71).
2. The assembly according to claim 1, wherein the one or more reinforcement materials are in a unidirectional, cross ply, non-woven or a woven form, which is preferably selected from plain, twill and satin weave forms.
3. The assembly according to claim 2, wherein the one or more reinforcement materials are in a satin weave form.
4. A method for production of an assembly (90) for use as a separator in aviation interiors; wherein the method comprises the following step-I and step-II:step-I) provision of a thermoplastic foam core (70); provision of a thermoplastic first skin (81) in which one or more reinforcement materials is embedded; followed bystep-II) securing the first skin (81) onto the foam core (70), by the following sequential sub-steps: (a) provision of an apparatus (1), comprising a first plate (10) and a second plate (20) opposing each other, arranged for approaching to one another in order to exert a pressure towards each other; (b) arranging that, when the apparatus (1) is in use at an operation of hot-pressing of the first skin (81) with the foam core (70), only one of the first plate (10) or second plate (20) is provided with a first heat at the operation of hot-pressing of the first skin (81) with the foam core (70), to an extent which provides a first hot-pressing temperature for fusion at an interface between the first skin (81) with the foam core (70);(c) placing the foam core (70) and the first skin (81) which is not yet secured to the foam core (70), inbetween the first plate (10) and second plate (20); such that the first skin (81) remains in-between the foam core (70) and the one of the first plate (10) or second plate (20) which is to be provided with said heat;(d) conduction of the hot-pressing operation by provision of said first heat towards the foam core (70), through the first skin (81); thereby partially fusing the first skin (81) with the foam core (70) through a first interlayer (91) that is formed by said fusion; thus obtaining the assembly (90).
5. A panel (100) for use in aviation interiors; the panel (100) comprising a core (75) sandwiched in-between a first skin layer (83) and a second skin layer (84); wherein the core (75) is in the form of a foam which is formed from one or more thermoplastics and the one or both of the first skin layer (83) and second skin layer (84) comprise one or more thermoplastics in which one or more reinforcement materials are embedded.
6. The panel according to claim 5, wherein the one or more reinforcement materials are in a satin weave form.
7. The panel (100) according to any of claims 5 or 6, wherein the panel (100) is formed from a pre-formed first skin (81) and a pre-formed second skin (82) both comprising one or more of the thermoplastics in which one or more of the reinforcement materials are embedded, respectively forming the first skin layer (83) and the second skin layer (84); and a pre-formed foam core (70) forming the core (72) and comprising one or more of the thermoplastics, sandwiched in-between the first skin (81) and second skin (82);such that, a first interlayer (91) is formed by fusion of the one or more thermoplastics at a first side (71) of the foam core (70), sandwiched in-between the resulting core (75) and first skin layer (83); and a second interlayer (92) is formed of the one or more thermoplastics by fusion at a second side (72) of the foam core (70), sandwiched in-between the resulting core (75) and first skin layer (83).
8. The panel (100) according to any of claims 5 to 7, wherein the one or more reinforcement materials are in a woven form; the woven form is preferably selected from plain, twill and satin weave forms; preferably satin weave form.
9. A method for production of a panel (100) for use in aviation interiors; wherein the method comprises the following step-I to step-IV:step-I) provision of a thermoplastic foam core (70); provision of a thermoplastic first skin (81) in which one or more reinforcement materials are embedded; followed bystep-II) securing the first skin (81) onto the foam core (70), by the following sequential sub-steps: (a) provision of an apparatus (1) comprising a first plate (10) and a second plate (20) opposing each other and arranged for approaching to one another in order to exert a pressure towards each other; (b) arranging that, when the apparatus (1) is in use at an operation of hot-pressing of the first skin (81) with the foam core (70), only one of the first plate (10) or second plate (20) is provided with a first heat at the operation of hot-pressing of the first skin (81) with the foam core (70), to an extent which provides a first hot-pressing temperature for fusion at an interface between the first skin (81) with the foam core (70);(c) placing the foam core (70) and the first skin (81) which is not yet secured to the foam core (70), inbetween the first plate (10) and second plate (20); such that the first skin (81) remains in-between the foam core (70) and the one of the first plate (10) or second plate (20) which is to be provided with said heat;(d) conduction of the hot-pressing operation by provision of said first heat towards the foam core (70), through the first skin (81); thereby partially fusing the first skin (81) with the foam core (70) through a first interlayer (91) that is formed by said fusion; thus obtaining an assembly (90);step-III) provision of a thermoplastic second skin (82) in which one or more reinforcement materials is embedded; followed bystep-IV) securing the second skin (82) onto the foam core (70), by the following sequential sub-steps: (e) arranging that, when the apparatus (1) is in use for an operation of hot-pressing of the first skin (81) with the foam core (70), only one of the first plate (10) or second plate (20) is provided with a second heat at the operation of hot-pressing of the second skin (82) with the foam core (70), to an extent which provides a second hot-pressing temperature for fusion at an interface between the second skin (82) with the foam core (70);(f) placing the foam core (70) and the second skin (82) which is not yet secured to the foam core (70), in-between the first plate (10) and second plate (20); such that the second skin (82) remains inbetween the foam core (70) and the one of the first plate (10) or second plate (20) which is to be provided with said heat;(g) conduction of the hot-pressing operation by provision of said second heat towards the foam core (70), through the second skin (82); thereby partially fusing the second skin (82) with the foam core (70) through a respective second interlayer (92) that is formed by said fusion; thus obtaining the panel (100).
10. The method according to claim 9, wherein the step-II comprises:in step-(c), the first skin (81) is placed onto the first plate (10) and the foam core (70) is placed onto the first skin (81), such that a first side (71) of the foam core (70) contacts and covers the first skin (81);in step-(d), the first heat is provided from the first plate (10) towards the foam core (70), through the first skin (81), for implementing a fusion of the one or more thermoplastics at the first side (71) of the foam core (70).
11. The method according to claim 10, wherein the step-IV comprises:in step-(f), the second skin (82) is placed onto the first plate (10) and the assembly (90) is placed onto the second skin (82), such that a second side (72) of the foam core (70) that is opposite to the first side (71) contacts and covers the second skin (82);in step-(g), the second heat is provided from the first plate (10) towards the foam core (70), through the second skin (82), for implementing a fusion of the one or more thermoplastics at the second side (72) of the foam core (70).
12. The method according to claim 9, wherein the step-II comprises:in step-(c), the foam core (70) is placed onto the first plate (10) and the first skin (81) is placed onto the foam core (70); such that the first skin (81) contacts and covers the first side (71) of the foam core (70);in step-(d), the first heat is provided from the second plate (20) towards the foam core (70), through the first skin (81), for implementing a fusion of the one or more thermoplastics at the first side (71) of the foam core (70).
13. The method according to claim 12, wherein the step-IV comprises:in step-(f), the assembly (90) is placed onto the first plate (10) and the second skin (82) is placed onto the assembly (90), such that a second side (72) of the foam core (70) that is opposite to the first side (71) is contacted and covered by the second skin (82);in step-(g), the second heat is provided from the second plate (20) towards the foam core (70), through the second skin (82), for implementing a fusion at the second side (72) of the foam core (70).
14. The method according to any of claims 9 to 13; comprising the arrangement of the one or more reinforcement materials in a woven form, preferably in one of plain, twill and satin weave forms.
15. The method according to claim 14, comprising the arrangement ofthe one or more reinforcement materials are in a satin weave form.