Thermocompression bonding apparatus for producing recyclable honeycomb plates and method of using the same

Abstract

The invention relates to a thermo-compression device for producing recyclable honeycomb plates with high mechanical strength, the proposed configuration of which allows high production speeds with an optimized operating width. For this purpose, the device comprises an area for continuous heating and pressing of the supplied sheets, a cooling area, a calendering area and a forming area. Advantageously, the forming area comprises a forming roller with projections arranged in successive rows on its surface, the rows being arranged crosswise to the sheet supply direction. In this way, a recyclable honeycomb plate is obtained. The invention also relates to a method which is carried out with the described thermo-compression device.

Description

[Technical Field]

[0001] The present invention relates to an improved thermocompression bonding apparatus and method for producing recyclable honeycomb plates with high mechanical strength that are produced at high speeds and with optimized working widths.

[0002] In this method, the thermocompression device applies a continuous process using multiple pairs of heated and unheated rollers, making it possible to produce recyclable honeycomb plates with several different cell opening sizes based on the use of different materials, such as carded nonwoven fabrics made from a combination of fibers with different properties and thermoplastic fibers, low basis weight fabrics, and hybrid fabrics combined with thermoplastic films.

[0003] Advantageously, the improved thermocompression apparatus allows for increased operating speeds and the production of recyclable honeycomb plates that are homogeneous across their surfaces, which leads to improved mechanical strength. [Background technology]

[0004] Honeycomb plates with high mechanical properties are known in the prior art as a construction solution, but these plates with high mechanical properties come at a high cost. Alternatively, honeycomb plates are known that offer lower economic costs but insufficient mechanical properties.

[0005] Furthermore, the known honeycomb plates are extremely difficult to recycle, in this sense aluminium, glass, paper and polypropylene stand out among the materials commonly used to form honeycomb plates.

[0006] The basic technologies existing in the honeycomb plate manufacturing industry are briefly described below.

[0007] <Paper Honeycomb Plate Expansion Technology>: This technology basically consists of applying adhesive strips to glue successive layers of thin paper or cardboard that are expanded to form a hexagonal shape. These honeycomb plates are limited in that they cannot be produced with large core thicknesses and small cell sizes.

[0008] <Plastic Sheet Extrusion Technology>: This system consists of extruding thin sheets of 100% thermoplastic polymer (mainly PP), which then pass in a semi-molten state over vacuum rollers and semi-hexagonal projections to form semi-hexagonal plates. These plates are then cut and continuously bent in a specific way. This system has limitations on the core thickness, density, usable polymers, and cell size. Furthermore, to produce honeycombs, a low basis weight web is always required on two sides of the honeycomb.

[0009] <High-Performance Honeycomb Plate Expansion Technology>: This system requires skilled operators for the manufacturing process. This technology can be used with materials such as Nomex paper, Kevlar®, and low-basis-weight industrial fabrics made of glass, quartz, and carbon. First, adhesive strips are applied to bond successive layers of the aforementioned materials, which are then expanded to form a hexagonal shape. These blocks are then immersed in a resin tank and cured in an oven. This impregnation and curing process can be repeated several times (up to 16 times depending on the conditions). Due to the high manufacturing costs, this technology is limited to the above-mentioned materials and specific high-performance applications.

[0010] <Expanded Aluminum Honeycomb Plate>: This system consists essentially of the same bonding and expansion process as above, but since aluminum maintains its semi-hexagonal bluntness once expanded, resin immersion and subsequent curing are not required. This system is limited in the sense that it can only be used with aluminum plates.

[0011] Based on the content described in the preceding paragraph, the commonly used manufacturing process for forming honeycomb plates prevents the use of materials different from commonly used materials, i.e., the honeycomb plate manufacturing technology is tailored to the above-mentioned materials, so it is impossible to use nonwoven fabrics and thermoplastic fibers made of fibers of different properties using currently known equipment for manufacturing recyclable honeycomb plates.

[0012] Furthermore, continuous thermocompression devices are known for the production of honeycomb plates from recyclable sheets of carded nonwoven fabric and thermoplastic fibers, as disclosed in Spanish Utility Model ES 1265289 owned by the applicant of the present invention, and these devices consist of a number of heated thermocompression rollers with semi-hexagonal projections.

[0013] In this sense, the thermocompression bonding device of Patent Application ES1265289 defines a forming zone where the temperature is lower than the melting temperature of the sheet, while the height of the protrusions gradually increases to generate a semi-hexagonal shape in the sheet. Next, an attachment zone is defined where a pair of rollers has a temperature higher than the melting temperature of the sheet of recyclable material, and the height of the protrusions of the pair of rollers remains constant relative to the maximum height of the final segment of the forming zone. In this sense, the thermoplastic fibers of the sheet are melted in the attachment zone, and then move to a cooling zone where a pair of rollers has a temperature lower than the temperature of the attachment zone, and the height of the protrusions of the pair of rollers remains constant relative to the attachment zone.

[0014] Thus, melting of the thermoplastic fibers of the sheet occurs in this region, causing the nonwoven fabric, which initially had the appearance and behavior of a woven fabric, to assume the strength of stiff cardboard or plywood.

[0015] However, since the apparatus having the above-described configuration can operate at a maximum speed of 1 m / min and a maximum width of 15 cm, it cannot operate at high speeds, which leads to higher operating costs in industrial production. Another drawback associated with the thermoforming apparatus described in Utility Model ES1265289 is that the material being thermoformed may agglomerate during operation, resulting in a material in which the molten thermoplastic fibers are not uniformly dispersed, thereby reducing the mechanical strength of the resulting honeycomb plate. Such material agglomeration can even result in the need to stop production to resolve the agglomeration. Summary of the Invention

[0016] The present invention relates to an apparatus that makes it possible to manufacture recyclable honeycomb plates using sheets of recyclable material in addition to other known sheets.

[0017] The sheets of recyclable material preferably consist of nonwoven fabrics, low basis weight fabrics or filament yarn fabrics made of fibers of different nature in combination with thermoplastic materials which may be in the form of fibers or thermoplastic films.

[0018] In the case of a sheet made of nonwoven fabric, the nonwoven fabric preferably constitutes 20% to 50% by weight of the composition of the sheet, while the thermoplastic material in the form of fibers constitutes 50% to 80% by weight of the composition of the sheet fed to the apparatus.

[0019] Preferably, the fibers constituting the nonwoven fabric of the sheet have a length of 30 to 70 mm, which provides high mechanical strength to the produced recyclable honeycomb plate.

[0020] Advantageously, the use of nonwoven fabrics, preferably produced by carding and airlaid techniques (techniques using air instead of water), allows the combination of fibers of different nature, for example: Natural fibers, especially linen, cotton, hemp, bamboo, etc. · Recycled fibers, especially recycled carbon fibers, recycled aramid fibers, various textile fibers, etc. The use of recycled fibers makes the proposed device environmentally friendly. Fire-resistant technical fibres, in particular aramid fibres, Pyrotex® fibres, Kynol® fibres, etc., and also fibres with high mechanical strength, in particular carbon fibres, aramid fibres, glass fibres, etc.

[0021] Furthermore, when the sheet has a nonwoven fabric, the thermoplastic material used in combination with it is particularly composed of thermoplastic fibers such as polypropylene (hereinafter referred to as PP), polyethylene (hereinafter referred to as PE), polyester (PET), polyamide (PA), polylactic acid (PLA), polyester / polyethylene or high-density polyethylene bicomponent fibers. The thermoplastic fibers enable the adhesion of the different fibers that form the sheet fed into the device by the application of temperature and pressure to form a honeycomb plate with a hexagonal shape.

[0022] Unlike known devices, the device of the present invention is capable of weaving low basis weight fabrics (preferably 40-150 g / m 2 It should be noted that a sheet made of a thermoplastic film (preferably with a basis weight of 20 to 75 g / m) can be used. 2 ) and this film is applied to both sides of a low basis weight fabric to produce a sheet that is fed into the heat and pressure bonding device proposed in this invention.

[0023] In this sense, the thermocompression device of the present invention makes it possible to produce recyclable honeycomb plates, for which purpose sheets of recyclable material comprising fabric and thermoplastic material are fed into the aforementioned device.

[0024] The thermocompression bonding apparatus of the present invention has the following areas: an area for continuously heating and pressing the sheet having at least a first infrared radiant heating element and a heat pressing roller, wherein the temperature of the area for continuously heating and pressing is equal to or higher than the melting temperature of the thermoplastic material of the sheet; a cooling area for cooling the seat having a water-cooled cooling element; a calendering zone for calendering the sheet, the calendering zone having at least a second infrared radiant heating element at a temperature equal to or higher than the melting temperature of the thermoplastic material of the sheet; A forming zone where forming rollers are placed at a temperature lower than that of the calendering zone.

[0025] In this way, the thermocompression roller and the forming roller are arranged in pairs, and the forming roller has protrusions with a semi-hexagonal geometric shape, which are arranged in continuous rows distributed on the surface of the forming roller, and the rows are arranged crosswise to the sheet feeding direction in the thermocompression device.

[0026] Advantageously, the novel configuration of the proposed device also allows the use of fabrics of filament yarns combined with thermoplastic fibers to manufacture the sheets fed into the device.

[0027] The improved thermocompression bonding apparatus of the present invention has a novel configuration that allows the sheet feeding speed to be increased to at least 4 m / min, which means that the production of recyclable honeycomb plates at a rate of at least 4 m / min can be achieved, making it ideal for industrial production.

[0028] Furthermore, the manufacturing method of the present invention allows the production of a new generation of recyclable honeycomb plates with optimized mechanical properties and a very competitive quality / price ratio. These new cores with honeycomb or hexagonal shapes differ from commercially available cores, particularly in one of the substrates that can be used for their production, such as nonwoven fabrics (composed of reinforcing fibers and thermoplastic fibers). The use of nonwoven fabric formats (carded or airlaid) is novel in this field, as current core production technology does not allow for such nonwoven fabric formats.

[0029] The use of nonwovens as a base therefore reduces the cost of the final product and also offers the possibility of using very different reinforcements, which leads to greater potential for cost / performance optimization compared to commercially available honeycomb plates, as the composition of the core can be specifically adapted to the properties of the physico-mechanical requirements of the application in use.

[0030] In this sense, the method for producing a recyclable honeycomb plate of the present invention using the thermocompression bonding device described in detail above comprises the following steps: continuously feeding a sheet comprising a fabric and a thermoplastic material into an area for continuous heating and pressure application, using a drive roller for this purpose; a step of heating and pressing the sheet obtained in the previous step at a temperature equal to or higher than the melting temperature of the thermoplastic material, for which a first heating element and a heat pressing roller are used; feeding the sheet obtained in the previous step into a cooling area by means of a drive roller; cooling the sheet obtained in the previous step by means of a water-cooled cooling element; feeding the sheet obtained in the previous step into a calendering area by means of a drive roller; calendering the sheet obtained in the previous step by applying heat and pressure using a second heating element at a temperature equal to or higher than the melting temperature of the thermoplastic material of the sheet; - feeding the sheet obtained in the previous step into the forming area by means of forming rollers; The semi-hexagonal protrusions of the forming rollers cool and shape the sheet obtained in the previous process to produce recyclable honeycomb plates. [Brief explanation of the drawings]

[0031] For the sake of completeness of the following description and for the purpose of a better understanding of the characteristics of the invention, a set of drawings are attached as an integral part of said description, in which are depicted, in an exemplary and non-limiting manner:

[0032] [Figure 1] 1 shows a representation of a thermocompression roller that comprises a known thermocompression device. [Figure 2] FIG. 1 is a detailed front view of an example of a thermocompression roller that constitutes a known thermocompression bonding device. [Figure 3] 1 shows a sheet obtained from two thermocompression rollers that make up a known thermocompression device. [Figure 4] 1 shows a thermocompression bonding apparatus according to a preferred embodiment of the present invention. [Figure 5] 1 shows a detailed perspective view of a forming roller disposed in the forming area of ​​the thermocompression bonding apparatus shown in the previous figure. [Figure 6] 1 shows a front view of the forming roller depicted in the previous figure. DETAILED DESCRIPTION OF THE INVENTION

[0033] Figures 3, 4, 5 and 6 show a preferred embodiment of a thermo-compression apparatus for producing recyclable honeycomb plates of the type supplied in sheets (4) of recyclable material including fabric and thermoplastic material.

[0034] In this sense, the proposed thermocompression device includes a plurality of drive rollers (3), a plurality of heated thermocompression rollers (1), and a plurality of forming rollers (2) having protrusions (5) with a semi-hexagonal geometric shape, and the thermocompression rollers (1) and forming rollers (2) are arranged in pairs as depicted in FIG. 4.

[0035] The thermocompression bonding apparatus has the following defined areas: The area (8) for continuously heating and pressing the sheet (4) has heating elements consisting of at least a first infrared radiant heating element (6) and a heat pressing roller (1), and the temperature of the area (8) for continuously heating and pressing is equal to or higher than the melting temperature of the thermoplastic material of the sheet (4). Preferably, a pressure of at least 7 MPa is applied to the zone (8) for continuous heating and pressure application, which advantageously prevents shrinkage of the sheet (4) by melting the thermoplastic material at a pressure of at least 7 MPa. The cooling zone (9) for cooling the sheet (4) has water-cooled cooling elements (7). This allows for a smaller thickness of the sheet (4) compared to the thickness of the sheet (4) fed to the heating zone (8) and a homogeneous distribution of the thermoplastic material over the entire length of the nonwoven sheet (4). This homogeneous distribution leads to a final plate with optimal mechanical strength. The calendering zone (10) for calendering has heating elements consisting of at least a second infrared radiant heating element (6') at a temperature equal to or higher than the melting temperature of the thermoplastic material of the sheet (4). The purpose of this step is to slightly melt the thermoplastic material of the sheet (4) again before shaping it to produce honeycomb plates. The forming zone (11) is arranged with forming rollers (2) at a temperature lower than that of the calendering zone (10). Preferably, a pressure of at least 7 MPa is applied to the forming zone (11), and the forming rollers (2) having a semi-hexagonal shape cool the sheet (4), which then solidifies and permanently acquires a honeycomb structure. The protrusions (5) of each pair of forming rollers (2) are offset from one another to facilitate thermocompression of the sheet (4).

[0036] Therefore, to produce recyclable honeycomb plates using the improved thermocompression bonding apparatus of the present invention, the following method is followed: The sheet (4) containing the fabric and thermoplastic material is fed into the area (8) where it is continuously heated and pressed by the drive roller (3). The sheet (4) is heated and pressed by the first heating element (6) and the heat pressing roller (1) at a temperature equal to or higher than the melting temperature of the thermoplastic material. Preferably, a pressure of at least 7 MPa is applied in the heating and pressing step in the continuous heating and pressing zone (8). The sheet (4) is fed to the cooling area (9) by the drive roller (3). The sheet (4) is cooled by a cooling element (7). The sheet (4) is fed to the calendering area (10) by the drive roller (3). Calendering the sheet (4) by applying heat and pressure using a second heating element (6') at a temperature equal to or higher than the melting temperature of the thermoplastic material of the sheet (4). The forming rollers (2) feed the sheet (4) into the forming area (11). To produce recyclable honeycomb plates, the sheet (4) is cooled and shaped by the semi-hexagonal projections (5) of the forming roller (2). A pressure of at least 7 MPa is applied during the cooling and shaping process in the forming area (11).

[0037] Once the honeycomb plates are manufactured, they are glued together to form honeycomb panels. For this purpose, a process known as "hot melt lip" is used, whereby two plates are glued together by applying an adhesive. By gradually joining the pairs of plates together, honeycomb panels can be made up to 1m thick. 3 It is possible to obtain cubic blocks of the size of these blocks, which are then cut to the desired dimensions.

[0038] Alternatively, the process of bonding two honeycomb plates together can be carried out using a hot plate, and the thermoplastic material contained in the honeycomb plates itself allows the plates to bond when heated, eliminating the need for an additional adhesive.

[0039] It should be noted that the incorporation of the zones (8) for continuous heating and pressing and (9) for cooling is crucial for increasing the production speed relative to known devices and for ensuring the homogeneity of the honeycomb plates produced. This is due to the special properties of nonwoven fabrics when exposed to certain temperatures, which makes it impossible to apply high production speeds to known devices lacking the aforementioned zones (8) and (9). In this way, the combination of these four zones allows for an increase in production speed when using sheets made of nonwoven fabric and thermoplastic material, since a completely flat sheet is produced in the two first zones (8) and (9), and then the desired zones are formed on said sheet in zones (10) and (11).

[0040] One of the novel aspects of the improved thermocompression bonding device of the present invention is the arrangement of the protrusions (5) on the forming roller (2). In this sense, as can be seen in Figures 5 and 6, the protrusions (5) of the forming roller (2) are arranged in successive rows on the surface of the forming roller (2), the rows being arranged perpendicular to the sheet feed direction (4). This perpendicular arrangement in turn improves production speed, ensures uniformity over the entire length of the sheet (4), and allows for maximum utilization of its surface, since its entire width is utilized.

[0041] The novel arrangement of the protrusions (5) on the forming roller (2) of the device of the present invention produces very advantageous effects that could not be achieved with the known roller (101) depicted in Figures 1, 2 and 3.

[0042] In this sense, it can be seen that in known devices the projections (100) of the forming roller (101) are arranged longitudinally relative to the direction of feeding the sheet (102), as can be seen in FIG.

[0043] Known equipment is limited to both a maximum speed of 1 m / min (which is considered very slow) and a forming width of 15 cm (on an industrial scale, this would be about 100-200 cm), making processing extremely difficult to the point that higher production speeds or larger forming widths are virtually impossible to produce.

[0044] However, in the improved thermocompression bonding apparatus of the present invention, the projections (5) are arranged transversely to the sheet feed direction, which leads to a faster, more efficient and more uniform process.

[0045] The inventive thermocompression device proposed here is capable of operating at a speed of at least 4 m / min for feeding the sheets (4) of recyclable material.

[0046] Similarly, the fabric of the sheet (4) is preferably a nonwoven fabric, 40 to 150 g / m 2 gram weight of the fabric or fabric with filament yarns, while the thermoplastic material of the sheet (4) is between 20 and 75 g / m 2 It is noted that the thermoplastic fiber or thermoplastic film is composed of between 100 and 150 grams.

[0047] Finally, it is pointed out that the honeycomb plate obtained after the forming area (11), i.e., the step of cooling and forming the sheet (4), has a width of 100 to 200 cm and is a homogeneous, recyclable honeycomb plate with optimized mechanical strength.

Claims

1. A thermocompression device for producing recyclable honeycomb plates of the type supplied with sheets (4) of recyclable material including fabrics and thermoplastic materials, comprising a plurality of drive rollers (3), a plurality of heated thermocompression rollers (1), and a plurality of forming rollers (2) having protrusions (5) with a semi-hexagonal geometric shape, the thermocompression rollers (1) and the forming rollers (2) being arranged in pairs, characterized in that the thermocompression device is defined by: an area (8) for continuous heating and pressing of the sheet (4) having at least a first infrared radiant heating element (6) and a heat pressing roller (1), the temperature of the area for continuous heating and pressing being equal to or higher than the melting temperature of the thermoplastic material of the sheet (4); a cooling area (9) for cooling the sheet (4) with a water-cooled cooling element (7); a calendering area (10) for calendering the sheet (4), having at least a second infrared radiant heating element (6') at a temperature equal to or higher than the melting temperature of the thermoplastic material of the sheet (4); a forming zone (11) in which the forming rollers (2) are arranged at a temperature lower than that of the calendering zone (10); The protrusions (5) of the forming roller (2) are arranged in successive rows on the surface of the forming roller (2), said rows being arranged transverse to the feeding direction of the sheet (4).

2. 2. A thermocompression device for producing recyclable honeycomb plates of the type supplied with sheets (4) of recyclable material according to claim 1, characterized in that in the successively heated and pressed zone (8) and the forming zone (11) a pressure of at least 7 MPa is applied.

3. Improved hot pressing device for manufacturing recyclable honeycomb plates of the type that feeds a sheet (4) of recyclable material according to claim 1, characterized in that the feeding speed of the sheet (4) of recyclable material is at least 4 m / min.

4. The fabric of the sheet (4) is a nonwoven fabric, 40 to 150 g / m ２ Improved thermocompression device for producing recyclable honeycomb plates of the type supplied with sheets (4) of recyclable material according to claim 1, characterized in that they are fabrics with a low basis weight of 1000 or fabrics with filament yarns.

5. The thermoplastic material of the sheet (4) is 20 to 75 g / m ２ Improved thermocompression apparatus for producing recyclable honeycomb plates of the type supplied with sheets (4) of recyclable material according to claim 1, characterized in that they consist of thermoplastic fibers or thermoplastic films.

6. Improved thermocompression device for producing recyclable honeycomb plates of the type supplied with sheets (4) of recyclable material according to claim 1, characterized in that the honeycomb plates obtained in the forming area (11) have a width of 100 to 200 cm.

7. A method for producing a recyclable honeycomb plate by means of a thermocompression bonding device according to any one of claims 1 to 6, characterized in that it comprises the following steps: - feeding a sheet (4) comprising a fabric and a thermoplastic material into an area (8) where it is continuously heated and pressed by a drive roller (3); - heating and pressing the sheet (4) by means of a first heating element (6) and a heat pressing roller (1) at a temperature equal to or higher than the melting temperature of the thermoplastic material; - feeding the sheet (4) into a cooling area (9) by means of a drive roller (3); - cooling the sheet (4) by means of a water-cooled cooling element (7); - feeding the sheet (4) into the calendering area (10) by means of a drive roller (3); - calendering the sheet (4) by applying heat and pressure with a second heating element (6') at a temperature equal to or higher than the melting temperature of the thermoplastic material of the sheet (4); - feeding the sheet (4) into the forming area (11) by means of forming rollers (2); - Cooling and shaping the sheet (4) by the semi-hexagonal projections (5) of the shaping roller (2) to produce recyclable honeycomb plates.

8. The method for manufacturing a recyclable honeycomb plate according to claim 7, wherein the honeycomb plate obtained in the step of cooling and shaping the sheet (4) has a width of 100-200 cm.

9. 8. The method for manufacturing a recyclable honeycomb plate according to claim 7, characterized in that the honeycomb plate obtained in the step of cooling and shaping the sheet (4) is subjected to a step of adhering to another honeycomb plate by disposing an adhesive thereon.

10. The method for manufacturing a recyclable honeycomb plate according to claim 7, characterized in that the honeycomb plate obtained in the step of cooling and shaping the sheet (4) is subjected to a step of bonding to another honeycomb plate by a hot plate.

11. 8. The method for producing a recyclable honeycomb plate according to claim 7, characterized in that a pressure of at least 7 MPa is applied in the heating and pressing step in the zone for continuous heating and pressing (8) and in the cooling and forming step in the forming zone (11).

12. 8. The method for producing recyclable honeycomb plates according to claim 7, characterized in that the speed at which the sheet (4) is fed into the thermocompression device is at least 4 m / min.

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