NL193805C - Method for making a self-supporting plate-shaped soundproofing element. - Google Patents

Description

1 193805

Method for making a self-supporting plate-shaped soundproofing element

The present invention relates to a method for manufacturing a self-supporting plate-shaped soundproofing element, wherein a plastic foam core layer is manufactured from open-celled plastic foam which is compacted by heating this foam and simultaneously apply a pressure load thereon, so that the thickness of the damping element is density of the foam varies, after which two different top layers are applied on either side of the core layer.

Such a method is known from British patent specification GB-A 2,040,948.

The drawback of a sound-damping element manufactured according to the known method is that it absorbs only a very small range of different sound frequencies. Another drawback is that the sound-damping element manufactured with the known technique is hardly self-supporting, which is precisely a desirable property in many applications.

The object of the present invention is to remedy or at least alleviate the above-mentioned drawbacks of the known art, and to this end a method is provided which is distinguished in that the open-cell plastic used is highly elastically deformable and is built up at the start of manufacture as a spatial framework of rod-shaped connectors, that the temperature during processing increases to 150 ° C, that the temperature during processing of the plastic foam is not homogeneously distributed over the thickness, so that the density of the foam after processing, depending on the temperature distribution over the thickness, increases linearly or progressively in the direction of both coatings.

With a method according to the invention it is possible to produce self-supporting sound-damping elements from highly elastically deformable open-cell plastic foam. Soundproofing elements manufactured in this way acquire a self-supporting property, partly due to the non-homogeneous temperature distribution over the thickness of the core element, whereby the core layer can only be compressed in those areas which are important to achieve the self-supporting property. In addition, 25 other areas in the core layer remain uncompressed, so that the sound-damping element can damp sound in a wide range of different sound frequencies. At a temperature which can rise to 150 ° C, the process is furthermore very energy-efficient, because the time required for the deformation can be shortened.

In an embodiment of the invention, the method has the property that the cover layer is moisture-repellent, in particular as a polyethylene film, and the open cells of the edge region of the core layer through openings in the cover layer, respectively the adhesive layer or the polyethylene film are connected to the ambient air. This prevents capillary action of the open-cell core layer, while still allowing the moisture that has penetrated into the core layer to escape as water vapor. It is possible for the moisture-resistant covering layer or the polyethylene film to be applied on the side remote from the core layer for a fiber mat (14) with fibers or threads that are resistant to high temperatures, which fiber openings comprise openings distributed over the surface. and in particular if a net is constructed. As a result, the sound-damping elements produced by the method according to the invention can also be arranged in the vicinity of sound sources emitting high temperatures. In addition, improved protection against mechanical damage to such sound dampening elements is provided. The reinforcement of the edge area associated with this fiber mat already absorbs a large part of the incident sound when this part of the soundproofing element penetrates and it is ensured that the air for soundproofing is also impeded by the accessibility and air permeability of this fiber mat. the soundproofing element can penetrate. It is advantageous here that the fibers or wires are formed by glass fibers and / or 45 carbon fibers and / or metal fibers. This is advantageous because, in addition to a high mechanical strength, such mats can also withstand a high thermal load and are also resistant to the influence of oil and grease.

Preferably, an embodiment of a method according to the invention, in which the fiber mat described above is applied, has the property that on the surface 50 of the other covering layer facing away from the fiber mat, a mat of water-repellent fiber fleece and or of foam material, for example of an open cell soft foam is applied, the thickness of which is part of the thickness of the core layer. This further dampens the sound waves penetrated by the open-cell structure of the sound penetrating to the surface to be protected, before they reach this plane.

In a method according to the invention it is also possible that an elastically deformable supporting body is provided in the core layer and, respectively, or in the region between the core layer and the fiber mat or mat, which air and / or respectively sound-permeable.

Sound-damping elements produced in such a way can easily be adapted to complicated spatial design, such as, for example, to the internal shape of a bonnet or the like, and to be attached to such parts by supporting bodies which make this design possible. It is further possible here that the support body and / or the adhesive layer and, respectively, or the covering layer and, respectively, or the fiber mat and the mat, respectively, are water vapor permeable.

5 This avoids damage by moisture and associated deterioration of the sound-damping properties of the sound-damping element.

For a better understanding of the invention, it will be explained in more detail below with reference to the illustrative embodiments shown in the drawings.

Figure 1 shows a sound-damping element manufactured with the method according to the invention in perspective, simplified, schematic representation.

Figure 2 shows a cross-section through an edge region of a core layer of a sound-damping element manufactured by the method according to the invention, in which the connecting spots with a schematically indicated covering film, as well as the areas where the adhesive is applied to the cell structure, are visible. .

Figure 3 shows a front view of an engine compartment with sound-damping elements arranged on the inside of the engine compartment, manufactured by the method according to the invention, as well as the mounting devices of these sound-damping elements on the hood.

Figure 4 shows a sound-damping element manufactured with the method according to the invention in perspective view.

Figure 5 shows a cross-section through another sound-damping element in top view.

Figure 6 shows a part of the core layer of a soundproofing element manufactured by the method according to the invention, with a perspective view schematically showing the different cell structures in the compacted edge and in the middle region.

25

Figure 1 shows a self-supporting, sandwich-like sound-damping element 1. This soundproofing element 1 comprises two cover layers 2, 3 and a core layer 4.

In the present exemplary embodiment, the core layer 4 consists of two plates 5,6 of a soft foam, which, as schematically indicated, have a lower density in a central region 7 of the core layer 4 than in the edge regions 8, 9 of the core layer 4. In the central embodiment 7 of the core layer 4, a supporting body 10, for example a wire grid or a wire net or the like, is arranged between the facing surfaces of the two plates 5 and 6. The support body 10 is preferably elastic and can be permanently deformed into arbitrary spatial shapes by the action of pressure.

An adhesive layer 11 is provided to connect the two plates 5, 6 and the supporting body 10, which layer can also be formed, for example, by a melting foil, for instance a polyethylene foil or the like.

In the edge regions 8, 9, a fiber mat 14 and a mat 15, which form the cover layers 2, 3, are also connected to the plates 5, 6 by means of an adhesive layer 12, 13.

The adhesive layer 12, 13 can again be formed by melting foils, such as for instance a polyethylene foil or the like. When using polyethylene films as adhesive layers, these are preferably provided with openings distributed over the surface, so that an air passage between the plates 5, 6 and these plates 5, 6 and the fiber mat 14 and the mat 15, respectively, is ensured. By the use of the openings 16, the air in the cells of the plates can pulsate, so that the air-45 sound vibrations are damped through the labyrinth-shaped passages in the open cell structure of the core layer 4, respectively of the plates 5, 6 forming these. In addition, through these openings 16 it is ensured that any gaseous moisture which has penetrated into the sound-damping element 1 can escape in a gaseous state, but with an appropriate choice of the size and the number of openings made in the surface unit, the penetration of water into liquid shape as good as possible can be avoided.

For mounting the soundproofing element 1, holders 17 are attached to the supporting body 10, which co-act with connecting means 18 to fix the soundproofing elements 1 to a part 19, which must be protected against the sound effects of a sound source 20. The connecting means 18 can for instance be formed by fixed 55 pins or bolts or the like attached to part 19.

Depending on the purpose of the sound-damping element, fibers or wires 21 of the fiber mat 14, in particular in the vicinity of sources of sound emitting higher temperatures, such as motors, compressors or the like, can also be formed by high-temperature-resistant glass fibers , metal fibers or carbon fibers or the like. By such an embodiment of the fiber mat, the adhesive layer 12 and the edge region 8 are protected against the action of too high temperatures.

The mat 15 arranged on the part 19 - which is arranged on the side of the sound-damping element remote from the sound source 20 - is formed, for example, by a non-woven fabric or by a mat of soft foam. The covering layer 2 or fiber mat 14 or the covering layer 3 and the mat 15 respectively have a thickness 22 and 23 respectively, which is a part of a thickness 24 of the core layer 4. The mat 15 can be formed by a water-repellent fiber web or by a foam mat 10 of a soft foam with predominantly open cells.

As indicated by the schematic representation of the middle area 7 and the edge areas 8, the core layer 4 has an increasing density in the direction of the two cover layers 2, 3. While the middle layer preferably has a specific gravity of 10 kg / m3, the specific gravity of the soft foam in the edge regions 8, 9 is about 18 to 20 kg / m3. As a result, different sound transmission values are achieved over the thickness of the core layer 4, so that approximately equally good sound attenuation values for different frequencies are achieved with one sound attenuation element 1. In addition, due to the higher specific weight in the edge regions 8, 9, a greater strength and stability of the core layer 4 in the edge regions 8, 9 is achieved. This provides favorable conditions for the attachment of the cover layers 2, 3 to the core layer. Due to the greater strength of the edge areas 8, 9, the sound-damping element can be made self-supporting without additional measures, only by connection to the cover layers. It has been found to be advantageous if the different specific gravity of the edge regions 8, 9 relative to the middle region 7 of the core layer 4 is achieved in that plates of the same thickness are compacted by the action of pressure and temperature in the edge regions. As a result of the breakdown of the open-cell cell structure due to the effect of temperature in these compacted areas, a greater number of closed cells are created than in the middle area 7. By a suitable change in the thickness of the edge area 8, 9 or the space weight in relation to the space weight of the middle region 7, an adaptation of the sound-damping element to different sound sources or different frequencies of the sound waves emitted from such sound sources can be achieved. Preferably, plates are used for the core layer, which are cut from a block of soft foam. The soft foams used for the production of the plates may be polyether or polyester plastic foam, which is driven in particular by MDI or cross-linked. The advantage of using plates cut from a block of plastic foam lies in that the density and the cell structure are as uniform as possible.

Within the scope of the invention it is irrelevant here whether the core layer 4 consists of a single plate or of two plates 5 and 6, as shown in figure 1, or of more plates of different density or cell structure, for example a plate for the middle region 7. and each time a plate for the edge regions 8, 9 is formed.

For the production of such a sound-damping element 1, as shown in figure 1, it is now possible to work according to the following method: 40 Plates are manufactured from a soft foam material with uniform density substantially throughout its thickness, in which, for example, one consists of a wire mesh or wire grid existing support body 10 is foamed. Optionally, however, it is also possible to use plates 5, 6 cut from a block of soft plastic foam, between which an adhesive layer 11 and the support body 10 are arranged. At the same time, in a heated press for the production of the sound-damping element 45, the covering layers 2 and 3 are laid in with the interposition of an adhesive layer 12, 13.

Subsequently, the press is heated in the region of the cover layers 2, 3 to a temperature of about 100 to 150 ° C and a suitable surface load is applied to the sound-proofing element 1 laid in the mold. Due to the load distributed over the surface under simultaneous temperature action, the cellular structure in the edge regions 8, 9 breaks down and the thickness of the core layer 4 decreases due to this compaction. Breaking of the cells due to the simultaneous action of pressure and temperature also results in a greater density and a higher specific weight of the foam in the edge regions 8, 9. By a suitable choice of the temperature and the pressure load, the thickness of the edge areas or the change in density and the specific weight can easily be adapted to different applications.

The adhesive used for the adhesive layer 11, 12 and 13 is preferably water-repellent and air-permeable, so that the air can enter unhindered into the areas behind the plates 5, 6 and the core layer 4, respectively.

193805 4

However, it is also possible for moisture insulation and for gluing the individual layers of the sandwich-like sound-damping element 1 together, instead of using adhesive layers of melting films, for example polyethylene films. When the soundproofing element 1 is heated, this foil melts and acts as a water-repellent protective layer and at the same time as an adhesive layer for connecting the individual 5 layers of the soundproofing element 1.

Due to the use of open-pore foams with high elastic properties in the area of the core layer 4 and in the area of the covering layer 3, the sound-damping element 1 can be mounted directly on a part 19 to be protected against the noise directed thereto.

It is advantageous here if the connection between the connecting means and the holder 17 to the carrying body 10 is effected by means of elastic intermediate elements, so that a vibration and thus sound transmission from the sound-damping element to the part 19 is reliably avoided.

Figure 2 shows part of the core layer 4. As can be seen, this core layer is composed of closed cells 25 and the interconnected open cells 26, which are formed by the net structure. In order now to allow an air passage through the adhesive layer between the cover layer 3 and the core layer 4, an adhesive 27 is used which has a consistency which does not allow the spanning of larger cavities, so that the adhesive 27 only against the net structure of the open cells 26 abut the closed cells 25, respectively. This ensures that air passages remain open in the connecting surfaces between the covering layer 3 and the core layer 4, through which the air can enter or exit the core layer 4.

Figure 3 shows the arrangement of sound-damping elements 1 on the inside of a hood 28, which is composed of hood parts 29 and 30, which for instance consist of glass-fiber reinforced plastic. Inside the hood 28, for example, is a diesel engine 31, which emits air and impact sound, which are symbolically indicated by arrows 32 and 33, in all directions. The sound-damping elements 1 are connected to the hood parts 29 and 30 by the carrying body 10 and the connecting means 18.

As can still be seen from Figure 3, it is possible, due to the deformability of the individual plates or elements of the sound-damping element, to adapt them to arbitrary spatial deformations of the hood parts 29 and 30 - as shown in particular in the case of the hood part 30 29 associated soundproofing element 1.

Of course, instead of the MDI-driven plastic foams, TTI-driven plastic foams can also be used.

The selection of the specific weights of the plastic foam in the edge and middle regions can also be varied in a suitable manner, in order to achieve better damping behavior, for example for more energy-rich energy vibrations.

It is also possible to use a cotton fiber fleece or a synthetic fiber fleece for the mat 15. If an adhesive is used for the adhesive layer, it must be ensured that it retains its adhesive effect even after heating to approx. 150 ° C or liquefies in this temperature range, for example during the temperature and pressure load of the soundproofing element 40 at the same time. be able to glue the individual plates or the layers, to ensure that a permanent glue connection is obtained in the sandwich. For the pressure and temperature loading of the sound-damping element during manufacture or deformation, the heated pressing devices known from the prior art can be used.

Figure 4 shows a sound-damping element 101, which consists of a covering layer 102 and a covering layer 103, and a core layer 104 arranged between these. The core layer 104 comprises, as schematically indicated, a central region 105 and two edge regions 106, 107. This core layer 104 can consist of one piece, of a plastic foam with predominantly open cells, in particular a plastic foam plate. However, it is also possible to merge the edge areas and the middle areas from your own plates. As indicated by the schematic representation from the cutting plane in the region of the head side, the edge regions 106, 107 and the middle region 105 have a different density of the open-cell plastic foam. These edge regions 106, 107 are thereby formed by pressurized plastic foam, that is to say mechanically and respectively or thermally compacted. Preferably, in this embodiment plastic foam with the same properties is used for the middle region 105 as well as for the edge regions 106, 107. When a one-piece core layer 104 is used, the edge regions 106, 107 are obtained by compaction applied in the surface region under simultaneous heat supply. As Figure 4 further shows, the regions 108 have a greater thickness 109 than the regions 110, which have only a thickness 111. As expressed by the schematic 5 193805, the core layer 104 in the region 110 is denser and accordingly has a greater density and thus a higher specific gravity. This is achieved in that the open-cell structure is more compacted by the higher pressure in the regions 110 under the simultaneous thermal load. It is also possible to expose the areas to be densified more strongly to a higher temperature, in order to facilitate deformation or permanent deformation of the open-cell plastic structure.

Preferably, an element having the same surface area in the region 110 of less thickness 111 and in the region 108 of greater thickness 109 has the same weight. The cover layers 102 and 103 may be formed by pressure and temperature deformable films or reticulated materials of fabric, fiber or other artificial or natural materials. Preferably it is possible to form one of the two cover layers 102, 103 from a cardboard saturated with unsaturated polyester resin. In one embodiment, in which the one cover layer 102 is formed by a cardboard saturated with unsaturated polyester resin, this cover layer 102, for example in a vehicle, is arranged near a body 112, for example the sheet metal parts of the cabin space. The fixing between the sound-damping element 101 or the covering layer 102 and the body 112 can be effected by gluing or by suitable fasteners of plastic or metal. The opposite cover layer 103 may be formed by carpets or leather or the like formed from artificial or natural fibers. When the cover layers 102 and 103 are directly joined together during the production of the soundproofing element 101, for example by using melt foils 113 - as schematically indicated in the lower part of figure 4 - care must be taken to ensure that the cover layers 102 and 103 allow for suitable elastic deformation and temperature loading.

With the sound-damping element 101 shown, for example, the soft foam or plastic foam with open-cell structure used can have a specific weight of about 9 to 10 kg / m3 and this material is used, for example, in the peripheral areas 106, 107, in particular also in the area, for example. 110, in which it has only a thickness 111, compacted to a specific weight of about 40 to 50 kg / m3. This leads to the fact that the denser structure of the soft foam in the region 110 creates a greater stability of the sandwich element with respect to the surface regions 108 and thus in those regions in which a thickness 109 of the sound-damping element is formed on the basis of the constructional requirements. 101 is not possible, yet sufficient strength against damage is ensured in normal operation. In spite of all this, however, with such a sound-damping element it is achieved that it has a high elasticity and that good damping properties are achieved in the impact of persons, since the more solid and strong compacted areas 110 open directly into the areas 108 with a higher elasticity and in general, therefore, the more compacted region 110 is more elastically damped than with a foam filling with plastic materials with predominantly closed cells.

Due to a suitable force and temperature action during the manufacture of the sound-damping elements, the density variation in the edge regions 106 and 107 can also decrease progressively in the direction of the middle region 105.

Figure 5 shows a cross-section through a sound-damping element 114, which can for instance be used as a covering element in a vehicle, for covering the interior space. As can be seen from this top plan view of the soundproofing element 114, it has differently thick and differently deformed surface areas 115, 116, 117 and 118. A core layer 119 and an associated cover layer 120 must allow sufficient deformation to produce the profiling of the soundproofing element without damage to the material. possible. To this end, it is possible, in the very highly compacted and weakened areas 117, 118 and in order to enable sufficient strength for the provision of connecting-45 devices, to provide supporting bodies 121 at least in separate areas in a favorable manner. which, after shaping the core layer 119, keep and stabilize these planar regions 117, 118 in the intended shape. The carrier body 121 may be mesh or foil-impregnated grids or grids impregnated with different resins or other glues, or grids and nets formed of metal or the like, which harden after the deformation and temperature treatment and keep the sound-damping element 114 in the desired shape.

Of course, it is also possible with this sound-damping element 114 to apply a further coating on the side of the core layer 119 opposite the cover layer 120.

Figure 6 shows a part of the core layer 122 and a cover layer 120 in highly simplified form and in perspective. By this representation, the mode of operation of the mechanical and 55 thermal compaction of the edge regions 123 relative to a center region 124 must be graphically explained. As can be seen, in the edge region 123 facing a surface 125 of the core layer 122 are the open cells 126, which are divided by a spatial lattice of plastic with a number of

Claims (8)

193805 6 joint walls 127 are formed, compressed by the mechanical and thermal compaction, thereby compressing and destroying the approximately spherical cells or the spherically constructed connecting surfaces 127 and preferably partially enclosed closed cells 128 relative to the center region 124, wherein these are approximately spherical, assume an elliptical shape. Due to the pressure and temperature, the open cells 126 and the connecting walls 127 forming them are compressed and deformed, increasing both the strength and the density and the specific gravity in the edge region 123. When this compaction takes place over a surface, it decreases in the direction from the middle region 124, depending on the selected processing criteria, linearly or progressively, to the middle region 124, in which the original unaltered cell structure remains. The solution distinguishes itself from those sound-proofing elements, where a foaming with skin formation is used, in order to achieve a hard surface with a soft core, because the densification of the edge areas can be regulated in arbitrary limits by the temperature and pressure applied. With reference to Figure 6, only the rationale, modifying the properties of soft foam fabric sheets by a suitable compaction, is shown schematically for a better understanding. Accordingly, arbitrary deviations may be present both with regard to the strongly exaggerated large proportions and the course of the connecting walls of the open cell structure. With regard to the coatings used, in the process, for example, fabrics, natural or artificial leather, non-woven fabrics, nets or the like can be used as coatings, whereby both natural and artificial fibers can be used. Preferably, these coatings may also be impregnated with or coated with moisture-resistant or flame-resistant materials. It is advantageous here if these additional applied or introduced materials only harden in the desired shape during the pressure and temperature treatment after the deformation of the soundproofing elements. This reliably prevents the spring-back of the sound-damping elements in their initial position. In the same manner, any desired material can also be used for the support body 121. It is thus possible to use suitable non-woven fibers, fiber nets or the like of metal, plastic or natural fiber and wires, preferably carbon fiber wires. It is furthermore advantageous if this support body is provided with a layer of unsaturated polyester resin and the support body thus retains in this deformed position during the temperature and / or pressure extension after deformation. It is of course also possible to place the support body between two suitably shaped foam plates and to bond these plastic layers by one or two adhesive layers, for instance melting foils. The soundproofing elements are preferably used in motor vehicles, in particular for the lining of passenger spaces or driver's cabs in trucks. However, these can of course also be used for insulation of flats or for the sound insulation of other machines. 40 A method for manufacturing a self-supporting plate-shaped sound-damping element, wherein a plastic foam core layer is manufactured from open-cell plastic foam which is compacted by heating this foam and simultaneously exerting a pressure bias on it, so that the density of the foam over the thickness of the damping element varies, after which two different cover layers are then applied on either side of the core layer, characterized in that the open-plastic material used is very elastically deformable and is constructed at the start of the production as a spatial framework of rod-shaped connectors, which the temperature during processing increases to 150 ° C, that the temperature during processing of the plastic foam is not homogeneously distributed over the thickness, so that the density of the foam after processing, depending on the temperature distribution over 50 the thickness, increases linearly or progressively in the direction of both e coatings. Method according to claim 1, characterized in that, with the heat treatment, coatings (2, 3) are simultaneously applied to the opposite surfaces of the core layer (4) and firmly bonded thereto, one coating (2, 3) ) are formed by a fiber mat and the other coating by a mat. Method according to claim 1 or 2, characterized in that a covering layer (2, 3) is designed to be moisture-resistant, in particular as a polyethylene film, and open cells (26) in the edge region (8, 9) of the core layer (4). ) are connected to the ambient air through openings in the cover layer (2, 3) or the adhesive layer (12, 13) or the polyethylene film. Method according to claim 3, characterized in that the moisture-resistant covering layer (2, 3) or the polyethylene film on the side facing away from the core layer (4) has a fiber mat (14) with fibers or threads (21) which are resistant to high temperatures, which fiber mat (14) has 5 openings (16) distributed over the surface and in particular is designed as a net. Method according to claim 4, characterized in that the fibers or wires (21) are formed by glass fibers and, respectively, or carbon fibers and, respectively, or metal fibers. Method according to claim 4 or 5, characterized in that on the surface of the other covering layer (3) facing away from the fiber mat (14), a mat (15) of water-repellent non-woven fabric and or or of foam material, e.g. of a open-cell soft foam, the thickness (22, 23) of which is part of the thickness (24) of the core layer (4). Method according to one of claims 2 to 6, characterized in that in the core layer (4) and respectively or in the region between the core layer (4) and the fiber mat (14) or the mat (15) an elastically deformable supporting body (10) is provided, which is air-permeable and / or sound-permeable in the direction of the cover layers (2, 3). Method according to one of claims 2 to 7, characterized in that the support body (10) and, respectively, either an adhesive layer (11, 12, 13) and, respectively, the covering layer (2, 3) and, respectively, or the fiber mat ( 14) and, respectively, whether the mat (15) is designed to be water vapor permeable. Hereby 3 sheets drawing