DEVICE FOR LAMINATED SEVERAL LAYERS ARRANGED IN A STACK TO FORM A LAMINATE COMPOSITE

Description

[0001] The invention relates to a device for laminating several layers arranged in a stack to form a laminate composite.

[0002] US Patent 5,728,309 A discloses a method for producing an organic matrix composite. An upper and a lower tool each comprise a tool insert, forming a common cavity. A retort is placed into this cavity. Subsequently, this retort is heated by means of induction coils and then subjected to pressure on one side so that it assumes the contour of the tool insert.

[0003] US Patent 6,109,903 A discloses a device for producing a rubber-metal composite. The rubber-metal composite to be produced is held between an upper and a lower plate. Furthermore, the rubber-metal composite is laterally surrounded by an induction coil. Due to the eddy currents generated by the induction coil, the metal plates are heated and bonded to the rubber layers arranged between them.

[0004] A multi-plate press is known from US patent 4,365,547 A. A pressing cycle begins with the closing of the press by bringing the pressing plates together. Simultaneously, steam is introduced into the pressing plates to expel the water contained within them. Subsequently, the steam pressure in the pressing plate is monitored to maintain the desired temperature.

[0005] From EP 1 340 611 A2, a plate press with a heating and cooling system for the production of coated, sheet-shaped products is known. Channels for a heating and a cooling fluid are provided in the press plates. These channels can be connected to either a heating circuit or a cooling circuit via mixing valves. These separate channels for the heating and cooling fluids in the respective press plate enable precise temperature control on the side of the press plate furthest from the product, so that any unwanted heating occurring during malfunctions can be actively counteracted.

[0006] From DE 10 2010 031 421 A1, a laminating device for laminating a multi-layered document is known, comprising two laminating plates between which a document to be laminated can be placed. The laminating plates consist of at least one electrically conductive ceramic material and have electrical connections, so that the laminating plates and the document can be heated by applying an electrical voltage to the electrical connections during a heating phase of the laminating process. After a predetermined laminating time, the heating phase, and thus the heating of the laminating process, is terminated. This is followed by a cooling phase in which the laminating plates are cooled by a coolant.

[0007] To laminate a document, it is placed between the laminating plates, the plates are pressed together, and the plates are heated by applying voltage to the electrical connections. After lamination, i.e., melting and bonding the individual layers of the document, the heating is switched off and the cooling fluid is supplied to the laminating plates.

[0008] DE 41 41 971 A1 discloses a method and a device for laminating layers using a press tool. Pressure and heat are applied to the layers to be laminated via the press tool. An analogous method and device are known from DE 41 41 972 A1.

[0009] US 2008 / 0190555 A1 discloses a method and a device for producing a laminate. This involves the use of a vacuum pressure device comprising a pressure block, fastening elements, and a heat-conducting block for heating a thermoplastic binder of the substrates.

[0010] WO 2015 / 148945 A1 further discloses a method and a device for the lamination of rigid substrates, wherein a sequential arrangement of vacuum and a mechanical force is carried out.

[0011] The invention is based on the objective of proposing a device for laminating several layers arranged in a stack to form a laminate composite, thereby reducing cycle times for the lamination process and improving the lamination.

[0012] The problem underlying the invention is solved by a laminating device in which the upper and lower laminating tools provided for the lamination process each comprise a laminating plate, wherein the laminating plates are metallic and have a thermal conductivity of at least 15 W / mK, preferably 50-80 W / mK. This enables a high heat flow. In addition, it is also possible to control a temperature gradient between the laminating plates and the stack during the lamination process.

[0013] The laminating plate of the laminating device is mounted on a monolithic component with a support plate, which includes a pressure chamber with an internal volume through which fluid can flow. This allows a heated fluid to be passed through during the heating phase to enable rapid heating. Subsequently, the cooling phase can be carried out by introducing a cool fluid.

[0014] To monitor the heating process or the lamination temperature of the laminating plates, the temperature of the laminating plates is preferably monitored and controlled by at least one temperature sensor, at least during the pressing process, and preferably during the entire heating phase of the lamination process. This allows for a brief reheating to be initiated even if the temperature drops too drastically.

[0015] The laminating sheets can be heated with a fluid. This has the advantage of providing a virtually carrier-free heat source that can control the heat flow during the lamination process within a short time.

[0016] The invention, as well as further advantageous embodiments and developments thereof, are described and explained in more detail below with reference to the examples shown in the drawings. The features that can be derived from the description and the drawings can be applied individually or in any combination according to the invention. The drawings show: Figure 1 a schematic view of a first embodiment of a laminating tool, Figure 2 a schematic sectional view along line II in Figure 1 , Figure 3 a schematic view of a laminating device with a laminating tool according to the Figures 1 and 2 , Figure 4 a schematic side view of an alternative embodiment of a laminating device not belonging to the invention in an open position, Figure 5 a schematic view of the laminating device according to Figure 4 in a closed arrangement, Figure 6a schematic side view of an upper pressing tool with a laminating plate and an associated closed fluid circuit, Figure 7 a diagram for the temperature development in the stack of layers according to a state-of-the-art process for producing a laminate composite and Figure 8 a schematic diagram of the temperature development in the stack of the laminate composite with the lamination devices described above.

[0017] In Figure 1 Figure 1 shows a schematic view of a first embodiment of a laminating tool 11. A schematic sectional view along line II is shown. Figure 2 stand out.

[0018] The laminating tool 11 comprises a laminating plate 12, which has an exemplary square or rectangular contour along which a support surface 14 extends. Opposite the laminating plate 12, a support plate 16 is provided, which is preferably aligned parallel to the laminating plate 12. A support structure 17 is provided between them, which distances the laminating plate 12 from the support plate 16. This support structure 17 is, for example, rib-shaped, web-shaped, or the like. This support structure 17 is surrounded by an outer wall 19, which adjoins the laminating plate 12 and the support plate 16. This forms a closed inner volume within which the support structure 17 is located. A connection for at least one inlet 21 and a connection for at least one outlet 22 are provided on the outer wall 19.In this embodiment, it is provided that, for example, two inlets 21 are provided on one side of the outer wall 19 and two outlets 22 are provided on the opposite side.

[0019] The support structure 17 is designed such that a medium which enters the internal volume of the laminating tool 11 through the inlet 21 can flow out via the outlet 22. For example, microchannels can be provided that run along the planar extent of the laminating tool 11. Alternatively, webs 23 can be provided that are spaced apart from each other and / or have openings or recesses to allow the flow of a medium.

[0020] The laminating plate 12 is preferably thicker than the carrier plate 16. The outer wall 19 is preferably designed as an elastic membrane, so that the laminating plate 12 can be slightly resilient relative to the carrier plate 16. Preferably, the laminating tool 11 is made of a single material and can be constructed, for example, by a 3D printing process such as laser sintering or laser melting.

[0021] In this embodiment, the laminating plate 12 is provided with connection contacts 25 for electrical leads, which lead to a control unit (not shown in detail). This allows the laminating plate 12 to be controlled as a resistance heating element to enable targeted and defined heating. Additionally or alternatively, the laminating plate 12 can be heated with a fluid flowing through its internal volume.

[0022] To cool the laminating tool 11, a cooled medium is supplied via the inlet 21, flows through the internal volume and is discharged via the outlet 22.

[0023] The flow of the cooling medium during the heating phase allows for rapid control or reduction of the heating temperature.

[0024] The contact surface 14 of the laminating tool 11 may have an embossed structure. For example, a dot-shaped or line-shaped structure may be engraved.

[0025] In Figure 3 Figure 1 shows a schematic side view of a laminating device 31, which has a lower tool 32 and an upper tool 33. A laminating tool 11 is attached to each of the upper and lower tools 32 and 33, respectively, according to the diagram. Figures 1 and 2fastened. In the lower tool 32, for example, several pressure dies 34 are provided. These can be arranged evenly distributed across the support surface 14 of the embossing plate 12. This is shown, for example, by dashed lines in the top view in Figure 3 shown. These pressure stamps 34 can apply an additional force to the laminating tool 11.

[0026] To laminate a stack 36 consisting of several layers 35 into a laminate composite 38, in which the layers 35 are permanently bonded together, the stack 36 is placed on a lower laminating tool 11. Subsequently, the laminating device 31 is closed, and in particular, the upper tool 33 is moved towards the lower tool 32 to exert laminating pressure on the stack 36. Even before the laminating device 31 is closed, the heating phase of a laminating cycle begins, and the laminating tool 11 is heated until the individual layers 35 of the stack 36 are bonded together to form a laminate composite 38. The heating phase is then terminated, and the cooling phase is initiated. A medium for cooling the laminating tools 11 is passed through the support structure 17. The laminating pressure within the laminating device 31 is maintained until the laminate composite 38 has cooled.The laminating device 31 is then opened and the finished laminate can be removed from the lower tool 32. The laminating device 31 is then ready for the next laminating process.

[0027] Alternatively to the one in Figure 3 In the illustrated embodiment of the laminating device 31, heating elements 38, particularly electric heating elements, can be provided, for example, between the pressure dies 34 on an underside of the laminating tool 11, in particular on the carrier plate 16. These heating elements 38 can also be used to heat the laminating tool 11.

[0028] The stack 36, which consists of several layers 35, can, for example, comprise at least one outer layer made of a thermoplastic elastomer that can be melted by applying heat, so that these outer layers, including inner layers that may be made of paper, form a closed encapsulation. Alternatively, the individual layers can all consist of a thermoplastic elastomer, so that they melt or fuse at least on the surface and bond with the adjacent layer to form a laminate composite, such as a card, in particular a PC card. Such a laminate composite 38 can be an access card, identification card, check card, or personalized card, such as an identity card or the like.

[0029] In Figure 4An alternative embodiment of the laminating device 31 is shown schematically. This laminating device 31 is in an open state.

[0030] In Figure 5 The laminating device 31 is arranged in a closed state. The laminating device 31 comprises an upper tool 32 and a lower tool 33, each with a laminating plate 12 and a sealing element 41 arranged between them. Between the upper and lower laminating plates 12, several superimposed layers 35 are provided in a stack 36 resting on the lower laminating plate 12, which are laminated to form a laminate composite 38 by a lamination process described in more detail below. Figure 5 They are connected. The upper and lower tools 32, 33 are, for example, designed as a single press plate. The laminating plates 12 are, for example, designed as thin metallic plates.

[0031] The sealing element 41 comprises a closed, circumferential body that is adapted to the planar extent of the upper and lower tools 32, 33. For example, the sealing element 41 as well as the upper and lower tools 32, 33 can have a rectangular contour.

[0032] The sealing element 41 has an upper contact surface 42 for contact with the upper tool 32 and lower tool 33. Opposite the upper contact surface 42, a lower contact surface 43 is provided for contact with the laminating plate 12. The sealing element 41 preferably has an inner circumferential surface 45, which is crescent-shaped or arcuate. This results in a concave inner end face on the sealing element 41. At least one inlet 21 and at least one outlet 22 for a fluid can be provided on an outer circumferential surface 44.

[0033] To carry out a lamination process, the upper tool 32 is closed by the lower tool 33, so that they exert pressure on the layers 35 of the stack 36 via the laminating plates 12 to form the laminate composite 37. During lamination, the upper tool 32 or lower tool 33 exerts pressure on the sealing element 41 relative to the respective laminating plate 12, so that a pressure chamber 46 is formed within it.

[0034] As an alternative to the inlet and outlet 21, 22, the inlet and outlet can also be in the plate-shaped material of the upper and lower tools 32, 33, so that the seal 46 consists exclusively of sealing material.

[0035] To monitor the temperature of the fluid flowing through the pressure chamber 46, a temperature sensor 47 is preferably provided, which is also connected to a control system not shown in detail.

[0036] In Figure 6A top tool 32 with a fluid circuit 45 connected to it is shown. The same applies to the bottom tool 14. This fluid circuit 48 includes a drain 22 associated with the top tool 32, which is connected to a low-pressure accumulator 49 for receiving the fluid discharged from the pressure chamber 46. A compressor 50 is provided downstream of the low-pressure accumulator 49. From the compressor, a supply branch 51 for hot fluid and a supply branch 52 for cool fluid are supplied with the fluid stored in the low-pressure accumulator 49. A storage tank 54 for hot fluid is provided in the supply branch 51. This preferably includes a heating element 55. Hot fluid is supplied from the storage tank 54 to the pressure chamber 46 via a supply line to the at least one inlet 21 on the sealing element 41.

[0037] The supply branch 52 for cold fluid comprises a storage tank 57 for cold fluid and preferably a cooling element 58 associated with the storage tank 57. From this storage tank 57, a supply line leads to at least one inlet 21 on the sealing element 41 in order to supply the cold fluid to the pressure chamber.

[0038] A valve 60, in particular an inlet valve, is connected upstream of the inlet 21. Similarly, the outlet 22 is controlled via a valve 61, in particular an outlet valve. Additionally, a temperature and / or pressure sensor 47, 62 can be provided in the upper tool 32. Furthermore, a control unit 64 is provided, which controls the valves 60, 61 and acquires and evaluates data from the temperature and / or pressure sensor 47, 62. The control unit 64 can also be coupled to the low-pressure accumulator 49, the compressor 50, the heating element 55, the cooling element 58, and the accumulator 54 with respect to pressure and / or temperature at the accumulator 57 with respect to pressure and / or temperature. The aforementioned setup applies analogously to the lower tool 33.

[0039] To close the laminating device 11, the upper tool 32 and the lower tool 33 are moved into a closing position according to Figure 3 and 5The sealing element 41 is transferred. The applied pressing force of the upper and lower tools 32, 33 presses the respective sealing element 41 between the laminating plate 12 and the upper and lower tools 32, 33, thus forming a pressure chamber 46. Subsequently, the control unit 64 activates the opening of the valve 60 at the hot fluid inlet 21, allowing hot fluid to flow from the reservoir 54 into the pressure chamber 46. Once a predetermined pressure is reached in the pressure chamber 46, which is detected by the pressure and / or temperature sensors 47, 62, the valve 60 is closed. Additionally, the temperature in the pressure chamber 46 can be further increased by the heating elements 55. Once the lamination, in particular the welding of the layers 35, has taken place, the valve 61 is opened so that the hot fluid can flow out of the pressure chamber 46 via the drain 22 and into the low-pressure storage tank 49.Simultaneously, valve 60 at inlet 21 for the cool fluid is opened, allowing cool fluid to flow from reservoir 57. As soon as the temperature sensor 47 in the pressure chamber detects cool fluid, valve 61 closes. Cool fluid continues to be supplied via reservoir 57 until the required pressure is reached in pressure chamber 46. This is then detected by temperature and / or pressure sensors 47, 62. Valve 60 for the cool fluid is then closed. After the laminate composite 38 has cooled, valve 61 at outlet 22 can be reopened. Similarly, at least one valve 60 can be used to supply the cool or hot fluid, so that after the upper tool 32 is lifted from the lower tool 33, the laminating plate 12 can be lifted from both the upper and lower tools 32, 33.The fluid stored in the low-pressure accumulator 49 can be compressed by the compressor 50 and selectively fed to the supply branch 51, 52. Preferably, warm fluid present in the low-pressure accumulator 49 is fed to the supply branch 51 and cool fluid to the supply branch 52. The arrangement of the accumulators 54, 57 in the fluid circuit 48 allows for rapid filling of the pressure chamber 46, in particular enabling heating of the stack 36 and subsequent rapid cooling of the laminate composite 38.

[0040] In Figure 7Figure 1 shows a diagram for a heating phase of a lamination process for producing a laminate composite 38 using a method known from the prior art. Time is plotted on the x-axis and temperature on the y-axis. The Tg line shows the glass transition temperature of the layers 35 to be laminated in the stack 36 to form a laminate composite 38. The glass transition temperature shown is adapted to the layer 35 that has the highest temperature for melting or partial melting.

[0041] After the laminating tools 11 are brought together to form a stack 36, they are heated at a constant temperature. In the case of a first embodiment of the Figures 1 to 3 and in the embodiment according to Figures 4 and 5 The respective pressure chambers are permeated with a hot fluid. In the case of an alternative embodiment of the Figures 1 to 3The resistance heating elements assigned to the laminating plates 12 are energized and heated to a constant temperature. The heating phase continues at a constant temperature until the individual layers 35 are partially or fully melted and laminated together. The temperature profile for the laminating plate 12 follows characteristic curve 71. For a layer 35 in the stack 36, for example, made of polycarbonate with a material thickness of 0.1 mm, the temperature profile follows characteristic curve 72. For another layer 35 in the stack 36, for example, made of polycarbonate with a layer thickness of 0.4 mm, characteristic curve 73 applies. The lamination point 74, at which the layers 35 are partially or fully melted and bonded together, occurs after the glass transition temperature of layer 73 has been reached.

[0042] In Figure 8 is an analogous diagram to Figure 7The process results in a significant reduction in the lamination time 74, as a comparison of the diagrams shows.

[0043] During the heating phase of the lamination process, the laminating plates 12 are heated to a temperature represented by characteristic curve 70. At the beginning of the heating phase, the controlled heating temperature is significantly higher than the glass transition temperature of the layer 35 to be laminated in the stack 36. This excessively high heating temperature of the laminating plates 12 allows for a shorter heating time. This enables an initial steep temperature increase in the laminating plates according to characteristic curve 71. This, in turn, causes the temperature present in the laminating plates 12 to be transferred to the layers 35 in the stack 36. This also enables steep temperature increases for the layer according to characteristic curves 73 and 74. As the heating phase progresses, the heating temperature controlled by the laminating plates is reduced according to characteristic curve 70.A reduction is made such that the temperature of the laminating plates 12 remains above the line Tg. From the diagram according to... Figure 8 It can be seen that the characteristic curve 73 crosses the line Tg at a significantly earlier lamination time 74 than in the procedure according to Figure 7 This is the case. This results in the fusion or melting of the connecting layers 35 at an earlier time, which in turn shortens the work cycle.

[0044] The reduction of the controlled heating temperature for the laminating plates 12 is preferably controlled exponentially. Alternatively, a step function or a stepwise reduction is also possible.

Claims

1. Laminating device, comprising at least one laminating tool (11) which comprises an upper tool (32) and a lower tool (33) as well as at least one laminating plate (12) in each case, between which a stack (36) of several layers (35) is arrangeable to form a laminate composite (38), Characterized in that - the at least one laminating plate (12) is designed as a metallic laminating plate (12) having a thermal conductivity of at least 15 W / mK, - the at least one laminating plate (12) and a carrier plate (16) are designed as a monolithic component and form the laminating tool (11), which has a pressure chamber with an internal volume through which a fluid can flow.

2. Laminating device according to claim 1, characterized in that the at least one metallic laminating plate (12) has a thermal conductivity of 50-80 W / mK.

3. Laminating device according to one of the preceding claims, characterized in that during the laminating process in the heating phase, the temperature of the laminating plates (12) is detectable by at least one temperature sensor (43) and the heating temperature for the laminating plates (12) is regulated.