WO2013159240A1

WO2013159240A1 - Sound-absorbing element

Info

Publication number: WO2013159240A1
Application number: PCT/CH2013/000069
Authority: WO
Inventors: Robert Bähler
Original assignee: Akustik & Raum Ag
Priority date: 2012-04-26
Filing date: 2013-04-23
Publication date: 2013-10-31
Also published as: EP2841660A1; CH706394A2

Abstract

The invention relates to a sound-absorbing element (10) comprising a cover layer (2, 2.2) having a micro perforation (21); a substrate layer (1) having a plurality of through-passages (11), such as in particular bores or slots; and an intermediate layer (3, 3.2), which holds the cover layer (2) spaced apart from the substrate layer (1), wherein the intermediate layer (3, 3.2) is designed to create a communicating connection between the micro perforation (21) of the cover layer (2) and passages (11) in the substrate layer (1) in order to produce a sound-absorbing effect.

Description

SOUND ABSORBING ELEMENT

TECHNICAL AREA

The invention relates to a sound-absorbing element, a composite and a method for producing a sound-absorbing element according to the features of the claims.

STATE OF THE ART

Sound-absorbing elements are used in interior design, on the one hand to influence the acoustic properties of a room and at the same time to make the room aesthetically pleasing. Sound-absorbing elements with a microperforated cover layer, which is adhesively bonded to a carrier layer provided with through openings, at the same time fulfill the sound-absorbing and aesthetic requirements. Areas of microperforation of the cover layer open into through openings in the carrier layer, with sound waves penetrating into the microperforation of the cover layer and being absorbed in cooperation with the through openings of the carrier layer, so that a sound-absorbing effect exists. The microperforation is barely perceptible to the human eye even at a small distance from the cover layer, so that the aesthetic impression of the cover layer, e.g. a plywood, comes to full advantage.

EP 1 876 308 shows a sound absorbing device with a plate-shaped core having a first and a second surface. A first coating

CONFIRMATION COPY and a second coating cover the first and second surfaces of the core, respectively. The first and the second coating are provided with grid-like arranged holes. The core is provided with a number of substantially parallel aligned grooves which penetrate the two surfaces of the core. By means of bonding, the coatings are glued to the surfaces, wherein holes of the coatings open into the grooves of the core. The holes have a diameter of 1 .1 mm or smaller and are spaced 1 mm or less apart. The grooves are about 3mm wide. The perforated surface of the coatings operatively associated with the grooves accounts for 50-70% of the total apertured coating. The sound-absorbing effect of the sound-absorbing device results from the interaction of the grooves of the core with the holes of the coating.

DE 1 98 39 973 shows a plate-shaped component of a perforated plate of solid material such as metal, wood, compressed wood, pressed board, plastic or plaster, wherein on one of the plate surfaces a micro-perforated film or thin plate or fabric web is arranged. The holes in the plate are formed so that they each open in a micro hole on one side of the plate. The sound-absorbing effect of the plate-shaped component results from the interaction of the holes of the plate and the microholes of the film.

EP 1 826 750 shows a sound-absorbing panel with a cover layer, which is glued to a support plate. The cover layer has a hole structure. The carrier plate has through channels which connect a first side of the carrier plate to a second side. The first side is provided with grooves, which are arranged to each other, that at least a part of the channels is connected to at least one groove. The grooves and channels have the function of finding the surface on the surface. fenden sound to steer the side facing away from the sound source. The grooves improve the sound-absorbing effect of the panel, since the hole structure of the cover layer has a sound-absorbing effect both in the area of the continuous channels and in the area of the grooves. The grooves are introduced by cutting blades or milling in the carrier plate. The channels are introduced by drilling or milling in the carrier plate.

PRESENTATION OF THE INVENTION

It is an object of the invention to provide a sound absorbing element which obviates or at least overcomes certain disadvantages of the prior art. It is a particular object of the invention to propose a sound-absorbing element which has an improved sound-absorbing effect. In particular, it is an object of the invention to reduce the proportion of inactive holes of a micro-perforation of a cover layer which has only a reflective effect rather than a sound-absorbing effect, since the holes of the micro-perforation of the cover layer, which is mounted on a carrier layer with through openings, only in the region of through openings of the carrier layer have a sound-absorbing effect and otherwise have a reflective effect. It is a particular object of the invention to propose a cost-effective sound-absorbing element with an improved sound-absorbing effect.

This object is achieved in particular by the features defined in the independent patent claims. To understand the present invention, the fundamental difference between passive and reactive absorbers is quite essential. The textbook "Sound Absorbers and Silencers" by Prof. Helmut V. Fuchs, Springer Verlag Berlin, Heidelberg New York 2007, 2nd edition provides a basic overview of materials and types of sound absorbers. In the following, the terminology specified by Prof. Fuchs shall be used with regard to the classification and differentiation of the different absorber types.

By far the largest and most important group of sound absorbers in terms of application width and market volume are the passive absorbers, as described in detail in Chapter 4 of the aforementioned textbook. In the passive absorbers, the sound energy is transferred to the otherwise passively behaving absorber by the friction of the air particles moving in the shaft with the very finely structured fibrous or open-pored material. Common materials for use in passive absorbers are fibrous materials, such as mineral fibers or organic fibers, open-cell foams and expanded building materials, as described in detail Chapters 4.1 to 4.3 of the book Schallabsorber and silencers and are characterized.

It is a characteristic feature of all passive sound absorbers to attenuate more at higher frequencies, while the power is often insufficient at low frequencies.

In order to protect the fibrous or porous absorber materials from mechanical damage and from contamination, and on the other hand to prevent the falling out or trickling of these materials, the absorber device must be used in virtually all applications. Covered. The cover must be designed in such a way that the sound can penetrate as unhindered as possible in the absorber material in order to be able to deliver its energy to the passively behaving material.

In order to achieve the required transmittance, the cover should either move freely or, in the case of a fixed or laminated cover, should not exceed a certain mass in order to impede the sound entry into the actual absorber material as little as possible (see chapter 5., page 41 of the above) cited publication "Sound absorbers and silencers ^" ).

Of the passive absorbers, the reactive absorbers are to be distinguished. The textbook ^" Sound Absorbers and Silencers ^" describes the plate resonators as the first group of reactive absorbers. They set the sound field to oppose an impermeable layer whose area-related mass m ^"is not small, but large compared to the mass of air moving in the impinging wave (according to Fuchs 3.2" Sound absorber and silencer ") The easiest way to do this is to attach a plate to a substructure at a distance from a reverberant rear wall, as indicated in Fuchs "Schallabsorber und Schalldämpfer" Fig. 5.1 Inside the disk space compressible air space, a thinner layer of fibrous or open-pore damping material should be loosely installed so as not to contact the disk as much as possible Therefore, their vibrations can neither hinder nor dampen directly. As another basic type of reactive absorber, Prof. Fuchs defines the Helmholtz resonators in chapter 6. While in the passive absorbers, the superior perforated or slotted plates serve only as sound-permeable layers for visual or shock protection and correspondingly impede the sound entry into the porous material as the actual absorber as little as possible, the air mass in holes or slots of differently perforated plates or membranes the Helmholtz resonators are not small compared to the mass of air in the wave striking the holes. The air mass in the holes or slots of the Helmholtz resonators, the u. U. by the holes or slots adjacent air may be additionally weighted, reacts with the sound field, similar to the plate resonator when it is made excitable as part of a resonance system. This is most easily done by a suitable perforated plate at a distance d to a reverberant rear wall (according to Fig. 6.1 in Fuchs: "sound absorber and muffler"), which rests on a substructure and acoustically closes the air cushion thus formed. In the Helmholtz resonators, in which the impact sound energy is converted into kinetic energy of the air mass, unlike the plate resonator can be completely dispensed with the use of or porous damping material. If this is not necessary, the damping of this "air in air" vibration system can be achieved very efficiently by mounting an optimum flow resistance according to Eq 4.7 (in "Sound Absorber and Silencer") directly in front of or behind the holes in the form of, for example, a fiber optic Fleece or cloth be accomplished.

Another group of reactive absorbers are the microperforated absorbers, which are treated in Chapter 9 of the book "Sound Absorbers and Silencers" by Prof. Fuchs. The example of microperforated plate absorbers (MPA) and microperforated ruled fabrics is explained how the friction in a variety of small holes and slots can be used to absorb sound energy. Preferably, the microperforated absorbers are mounted at a distance in front of a reverberant rear wall, so that the air in the many juxtaposed holes or slots as mass together with the air in the space to reverberant back wall as a spring in the manner of a Helmholtz resonator according to Ch. 6 (Fox: "sound absorber and silencer") can swing. The microperforated absorbers can do without the use of porous / fibrous damping materials. Since their acoustic effectiveness can be set almost exactly independent of the choice of the plate material, solely by their geometric parameters, micro-perforated absorbers allow for the first time optically transparent sound absorbers z. As acrylic glass, polycarbonate, PVC or ETFE.

According to Prof. Fuchs, only a relatively small hole area ratio σ (preferably of the order of 1%) is chosen for the microperforated absorbers over conventional hole surface absorbers and the slot resonators presented in Section 6.2. Above all, however, the smallest dimension of the holes or slots (2 r ₀ ) is always made so small that it comes within the order of the acoustic boundary layer of a laminar flow in the holes or slots (according to Fuchs:: "Sound absorber and silencer" Fig. 9.3 and Equation 4.1 3). In the figure 1 0 of the present application, the previously cited Fig. 9.3 is reproduced. In 10a), a microperforated absorber is shown schematically in plan view and section, in FIG. 10 b) the rapid distribution in large (left) or small holes or slots (right) is shown. In contrast to the passive absorbers, the microperforated absorbers do not have friction on thin fibers and in fine pores, which are spatially or planarly, more or less homogeneously distributed, but in narrow perforations, which in otherwise unpermeable, flat structures on manoeuvrable % of the area are concentrated. Microperforated absorbers have arbitrarily shaped holes whose at least half the transverse dimension is of the order of magnitude of the laminar boundary layer thickness in the respective medium. They allow - due to the muzzle effects at the small holes - sound attenuation even in infinitesimally thin layers of almost any impermeable materials and they can be just as varied as fibrous / porous absorbers with cavities behind / in front of the micro-perforated fabric couple.

Based on these foregoing embodiments, the present invention will be disclosed below.

A sound absorbing member according to the present invention comprises a resonator having a cover layer with a microperforation; a carrier layer with a plurality of through openings, in particular bores or slits; and an intermediate layer holding the cover layer spaced from the support layer, wherein the intermediate layer is formed to provide a communicating connection to improve the sound absorbing effect between the microperforation of the cover layer and openings of the support layer. The cover layer is held in a stably spaced manner over the intermediate layer on the carrier layer, in particular, wherein an integral connection such as, for example, a bond between the cover layer and the intermediate layer and between the intermediate layer and the carrier layer is provided. The intermediate layer is designed in particular sound permeable, so that between the microperforation of the cover layer and the openings of the support layer is an acoustically effective, communicating compound and the sound-absorbing effect of microperforation of the cover layer and the openings of the support layer is created. The intermediate layer has a structure which is suitable for stably holding the cover layer to the support layer, at the same time creating an acoustically effective, communicating connection between the microperforation of the cover layer and the openings of the support layer. Such a structure may preferably be formed as a three-dimensional structure (3 D structure), for example with a honeycomb material, a stiffened textile, a sufficiently stiff fabric or in another way. Preferably, the intermediate layer is stable enough to give the microperforated cover layer additional stability so that the stability of the support layer can be reduced without reducing the stability of the entire element.

A sound-absorbing effect results - as explained above for the microperforated absorbers - by the microperforation of the cover layer in cooperation with the air mass inside and possibly at the back of the absorber. As with all microperforated absorbers, the air moved by the sound rubs at the edges of the microperforation, transforming the sound energy into heat. As a result of the communicating connection between the microperforation of the cover layer via the intermediate layer and the openings of the carrier layer, the air can move and rub in the microperforation. In a hitherto known arrangement of a cover layer on a carrier layer, there are optical problems, since the micro-perforation which is located on openings of the carrier layer is perceived differently than the micro-perforation next to this opening, which is closed by the carrier layer and causing disturbing light reflections on the carrier layer form. Through the intermediate layer between the microperforated cover layer and the apertured Carrier layer these optical problems are solved, since no light reflections form on the carrier layer. The support plate can thus remain only roughly edited and there is no additional processing of the support plate such as covering with a black cover layer required. Thus, the workload in the production of sound-absorbing elements is additionally reduced. In particular, the microperforation is formed by holes having a diameter of 0.2 to 1 mm, preferably 0.5 mm, and a space between the edges of the holes of 10 mm or less. The open area formed by the microperforations in the cover layer is 1 to 7%, depending on the diameter of the microperforation, and according to preferred embodiments it is 6%.

In order to achieve very good acoustic attenuation properties over wide frequency ranges, a correlation of the diameter of the microholes with the open area in the cover layer has proven to be advantageous. Within the range of these two sizes given above, the formed open area in the top layer is very small hole diameters, such as 0.2 mm at about 1%, which corresponds to a number of about 300,000 holes per square meter. With the same number of holes, an open area of about 6% is achieved according to this correlation with a hole diameter of 0.5 mm.

In one embodiment, the cover layer comprises one or more of the following materials: a wood veneer, a wood material, a synthetic resin veneer, a plastic, a multi-layer resin impregnated paper, a metal foil, a metal plate. The choice of material of the cover layer allows the aesthetically pleasing design of rooms, which are equipped with the sound-absorbing element. The cover layer is preferably inherently stiff and non-porous except for the micro-perforations.

In one embodiment, the backing layer comprises one or more of the following materials: a wood, a wood material, a chipboard, an Oriented Strand board plate, a medium density fiberboard, a high density fiberboard, a hardboard, a plywood board, an organically bonded particulate bonded chipboard, in particular Plasterboard, a plasterboard, a honeycomb panel, a light metal plate, plastic, plaster, plasterboard or glass foam. The choice of material of the carrier layer makes it possible to provide dimensionally stable sound-absorbing elements at low cost. Preferably, the backing layer is provided with apertures that provide 20 to 40% open area. The openings may comprise holes and / or slots which are preferably drilled or punched in the carrier layer. Preferred thicknesses of the carrier layers are 1 2 to 1 9 mm. In the absorbers according to the invention, an intermediate layer stabilizing the cover layer can advantageously be used to stabilize the entire sound-absorbing element. Due to the additional stability of the at least one intermediate layer, the thickness and or stability of the carrier layer can be reduced and / or the open passage area can be increased without loss of stability of the entire absorber.

According to further advantageous embodiments, the carrier layer comprises a sandwich of at least two plates, which are connected to one another in a material-locking manner, preferably by gluing or welding. In order to give the product according to the invention particularly good fire protection properties, the side of the carrier layer facing the intermediate layer may have the form of a non-combustible plate, which preferably consists of an expanded mineral. The carrier layer is preferably non-porous, but the sound transparency of the carrier layer achieved through the openings also permits the use of porous materials.

An intrinsically stable intermediate layer, which additionally preferably stabilizes the cover layer, also makes it possible to increase the hole or slot diameter or length without increasing the risk of mechanical damage to the cover layer regions over the openings in the support layer.

In one embodiment, the intermediate layer comprises one or more of the following materials: a textile, in particular a three-dimensionally shaped textile such as, for example, a woven fabric, braid, knitted fabric, scrim; a textile made of knobs and fibers; a fiberglass material; a carbon fiber material; an aramid; a porous foam, in particular of glass, metal, ceramic; a stamped profile of metal or plastic with an embossment such as knobs, diamonds, pyramid, grooves; Honeycomb discs - preferably cut - soaked in polyamide, paper, cardboard, aluminum and / or the aforementioned materials or impregnated with aramid. The choice of material of the intermediate layer makes it possible at the same time to keep the cover layer on the support layer stable and to ensure the development of the sound-absorbing effect of the sound-absorbing element.

In one embodiment, the carrier layer is plate-shaped. Accordingly, the sound-absorbing element is plate-shaped. With plate-shaped sound-absorbing elements, rooms can be designed very efficiently and aesthetically pleasing.

In one embodiment, the microperforation of the cover layer has holes with a diameter of 1 mm or less and a mutual distance of 10 mm Or less. Holes with a diameter of 1 mm or less are barely perceived by the human eye even at a small distance to the sound-absorbing element. Thus, the aesthetic effect of the sound-absorbing element corresponds to the aesthetic effect of a cover layer without microperforation. By the distance of the holes 1 0mm or less, a sufficiently large number of holes can be provided, in which incident sound waves can penetrate.

In one embodiment, the carrier layer has through openings with a diameter of 4 mm or more and a mutual distance of 2 mm or more, preferably 2 to 4 mm. The diameters of the openings of 4 mm or more are chosen so that they do not significantly affect the stability of the carrier layer and thus of the sound-absorbing element. By a distance of 5mm or more, the stability of the carrier layer is further improved.

In one embodiment, an intermediate layer is provided on two opposite sides of the carrier layer, each of which holds a cover layer spaced from the carrier layer. The sound-absorbing element can thus effectively absorb sound waves on both sides. This is advantageous, for example, when installing the sound-absorbing element as a door.

In one embodiment, the backing layer has two opposing sides, and the intermediate layer holding the cover layer spaced from the backing layer is provided on one side of the backing layer, and on the other side of the backing layer, one or more of the following materials is attached: a nonwoven fabric, a fiberglass mat, a foam, a filler, an insulating material. Such a sound-absorbing rendes element can be mounted on existing walls, with only the visible side is provided with a relatively expensive cover layer with a micro-perforation and for the wall-facing side a cheaper and / or acoustically better effective material is selected. In one embodiment, the intermediate layer has a thickness of more than 0.8 mm, preferably between 1 mm and 3 mm, wherein the thickness is preferably 1 .5 to 2 mm.

The use of the intermediate layer according to the invention-preferably in the form of a spacer-allows 90% or more of the microperforations in the cover layer to be completely or partially open in the assembled state and thus remain acoustically active, so that the air mass in the microperforations is in line with the air mass in the absorber and at most on the back of the absorber in communicating connection and is available for sound absorption.

Preferably, the intermediate layer consists of a single layer. In addition to a sound absorbing element, the invention relates to a composite of a cover layer with a microperforation and an intermediate layer, which is connected to the cover layer, wherein the intermediate layer for the communicating compound is formed with an apertured carrier layer, wherein the cover layer is adapted to for producing a sound-absorbing effect of a sound-absorbing element formed between the cover layer, the intermediate layer and the carrier layer, between the microperforation of the cover layer and openings of the carrier layer, to establish a communicating connection. The composite of the cover layer with a microperforation and an intermediate layer can be used, for example, in a specialized factory. The sound-absorbing element is produced on site using a customary carrier layer. Since the weight of the cover layer with the intermediate layer is smaller than the finished sound-absorbing element, transport costs can be saved.

In one embodiment, the cover layer of the composite comprises one or more of the following materials: a wood veneer, a wood material, a synthetic resin veneer, a plastic, a multi-layer resin impregnated paper. The choice of material of the cover layer allows the aesthetically pleasing design of rooms, which are equipped with the sound-absorbing element.

In one embodiment, the intermediate layer of the composite comprises one or more of the following materials: a textile, in particular a three-dimensionally shaped textile such as, for example, a woven fabric, braid, knitted fabric, scrim; a textile made of knobs and fibers; a fiberglass material; a carbon fiber material; an aramid; a porous foam, in particular of glass, metal, ceramic; a stamped profile of metal or plastic with an embossment such as knobs, diamonds, pyramid, grooves. The choice of material of the intermediate layer makes it possible at the same time keep the cover layer spaced from the support layer stable and to ensure the development of the sound-absorbing effect of the sound-absorbing element. The choice of material of the intermediate layer may also be suitable for the transport of the composite, for example by the choice of material of the intermediate layer minimizes transport damage.

In addition to a sound-absorbing element and a composite of a cover layer and an intermediate layer, the invention relates to a method for producing a sound-absorbing element, wherein a cover layer with a microperforation, a carrier layer having a plurality of through openings, in particular bores or slits, and an intermediate layer which holds the cover layer spaced from the support layer, the intermediate layer being designed to produce a sound-absorbing effect between the microperforation of the cover layer and openings of the support layer to create a communicating connection.

According to further advantageous embodiments of the present invention, the sound-absorbing elements comply with strict fire regulations.

Primarily in public buildings, in larger rooms and in high-rise buildings, fire protection is an important and compelling topic. The sound-absorbing elements are often firmly connected to ceilings and walls with the basic construction of the building and are therefore subject to the building codes with appropriate building material classes. The classes of building materials are newly defined according to DIN EN 1 3501 - 1 and old according to DIN 41 02.1 as well as in test standards (EN ISO 1 1 82, EN ISO 1 71 6, EN ISO 9239 and EN ISO 9239-1). The present inventive elements without special fire protection, as well as many available on the market acoustic elements is about the classification A2 or B1 (non-combustible with low levels of combustible materials). For aesthetic reasons, preferably natural wood veneers or CPL laminates are used in the coverings of the elements according to the invention. These materials are classified as combustible building materials. The support layers are also classified according to fire requirements according to DIN 41 02 in B2-Normal Flammable, - B 1 Flame Retardant and A2 in non-combustible building material classes. While the previous fire protection classification was primarily based on the carrier material, which represents the essential fire load, acoustic elements are newly tested and classified in a network. So far, an element with a carrier material made of flame-retardant B l -MDF was classified in the fire class B 1. With a substrate made of A2 gypsum, the sound-absorbing element was classified in fire class A2.

After the new fire protection classification for acoustic elements, these are tested and classified "in combination", which means that cover layers and substrates including glue and paint layers but also with flame retardants are tested for fire The intermediate layers already mentioned above, in particular spacers made of non-combustible materials such as aramid (for example NOM EX honeycombs) or aluminum honeycombs, have in terms of the desired classification in B, preferably in A2 or particularly preferably A1 (according to DIN EN 1 3501 ) proved to be advantageous.

Also advantageous for the desired classification is an intermediate layer and / or a cover layer, which makes a very small, a negligible or no contribution to the fire. When using wood veneer and CPL laminate was according to the new regulation in the known elements a fire risk.

According to the present invention, the cover layer as well as the support layer can be selected from non-combustible materials such as aluminum or non-combustible fiber layers.

According to further embodiments, a flame retardant layer is arranged between the intermediate layer and the cover layer. If, for aesthetic reasons, a cover layer with a natural wood aspect is desired, according to the invention, a fire and / or flame retardant layer (hereinafter referred to as flame retardant layer) can be provided. The cover layer is provided for example with a coating or lamination comprising a fire and / or flame retardant, wherein the coating may also be a paint or a coating, and then micro-perforated.

Since the extremely thin outer layers of combustible materials such as real wood veneer and CPL laminates have low fire loads due to the low material thickness, the fire protection is already substantially improved by this measure. Also advantageous are composites of a very thin layer of wood (0.1 to 0.4 mm) and a non-flammable support layer of aluminum, glass fiber, carbon fiber or another non-combustible laminate arranged on the back of the cover layer. The different material expansions between such composite cover layers and the support layers can be compensated by the intermediate layer, for example a honeycomb structure.

According to further embodiments of the invention, the flame retardant layer is arranged on the back side of the cover layer and the microperforation is applied in the composite of flame retardant layer and cover layer or the flame retardant layer is arranged on the back side of the cover layer and comprises a nonwoven preferably of non-combustible material or a flame retardant impregnated nonwoven.

As a suitable flame retardant for creating flame retardant layers, expanded graphite has been found on the back of a combustible top layer of plywood and laminate. The function of the corresponding flame retardants is the following: The on The covering material (eg veneer wood) acting heat causes the flame retardant reacts and - in the case of expanded graphite - inflates and thus against the flame, a protective shield (a so-called intumescent) builds. The flame retardant does not burn on its own or only at very high temperatures of over 3000 ° C. As flame retardants several materials come into question. In the foreground is expanded graphite, which does not give off any harmful gases in a fire and already starts to swell at temperatures above 200 ° C. As a further flame retardant is polyam monophosphate with proportions of melamine / formaldehyde consensus available. Vermiculite three-layer silicate is another possibility in which an increase in volume also takes place (only at 1000 ° C.). Resins for flame-retardant impregnation are available with phosphor-reactive modified epoxy resin under Struktol VP 3757.

In the case of elements according to the invention having a covering layer of wood veneer or of combustible CPL laminate, according to one embodiment of the method according to the invention, the covering layer on the rear side is coated with a bound expandable graphite layer. Thereafter, the cover layer thus treated is perforated and then glued to the intermediate layer, for example a honeycomb disk, on the support plate.

Alternatively, the flame retardant, for example in the form of expanded graphite, can be applied to a nonwoven and subsequently the nonwoven treated in this way can be laminated to a cover layer of wood veneer or CPL laminate fleece. Thereafter, the thus laminated cover layer is perforated and then glued to the intermediate layer, preferably in the form of a honeycomb disc with the support plate. If a sound-permeable nonwoven material is used, then the top layer of wood veneer or CPL laminate can according to a further embodiment be microperforated in a first step. A thin sound-permeable glass fleece is mixed with expandable graphite and glued between perforated cover layer and intermediate layer, preferably in the form of a honeycomb disk.

In a further embodiment, a lacquer layer with flame retardant is applied to a thin non-combustible laminate. A particularly thin veneer wood is laminated on the back with this treated laminate plate and then micro-perforated as a cover layer. Subsequently, this cover layer is glued to the intermediate layer, preferably in the form of a honeycomb disk, and thus with the carrier plate.

In embodiments in which the spacer is directly connected to the cover layer, it is possible to provide this spacer with flame retardant, for example, to soak or paint. In case of fire and heat on the cover layer, the flame retardant reacts and causes the burning of the covering layer or forms an intumescent layer.

For elements whose intermediate layer comprises a honeycomb material, this is preferably made of flame retardant material, includes flame retardant material or the honeycomb are filled with sound-permeable flame retardant material.

In the latter case, the honeycomb are preferably filled with a suitable flame retardant such that the flame retardant, for example! a fire retardant such as expanded graphite, in case of fire, reacts directly with the combustible top layer (ie inflates and acts as a protective shield / intumescent layer). The flame retardant must be ganular or flaky, so that the sound transmission is maintained. Between perforated support plate and honeycomb comes advantageously a thin net or fleece, so that the flame retardant, such as the expanded graphite trickles / can escape from the honeycomb. According to further embodiments, the honeycomb material is soaked in a suitable flame retardant or sprayed with it, so that in particular adhering to the cover layer honeycomb edges, the flame retardant sticks and can get into fire on the combustible top layer of eg wood veneer or CPL laminate in function.

BRIEF DESCRIPTION OF THE DRAWINGS

On the basis of figures, which represent only embodiments, the invention will be explained below. Show it:

Fig. 1 shows schematically a perspective view of a sound-absorbing

element;

FIG. 2 schematically shows a cross-section of a foam-absorbing element which has a cover layer and a carrier layer; FIG. schematically a cross section of a sound absorbing member having a cover layer, an intermediate layer and a support layer; 4 schematically shows a plan view of an intermediate layer of a sound-absorbing element;

FIG. 5 Measurement of the sound absorption factor a _s as a function of the frequency f of an absorber according to the invention according to FIG. 1; FIG.

Fig. 6 schematically shows a perspective view of a sound-absorbing

Element according to another honeycomb spacer embodiment;

Fig. 7 perspective view of a sound-absorbing element according to

Figure 6 with measures of the openings in the support plate;

Fig. 8 perspective view of a sound-absorbing element according to

Figure 6 in a further embodiment with measures of the openings in the support plate;

Fig. 9 perspective view of a sound-absorbing element according to

Figure 6 in a further embodiment with measures of the openings in the support plate; and

1 0 a the prior art, wherein in Fig. 1 a) a microperforated absorber is shown schematically in plan view and section and in the figure 1 0 b) the rapid distribution in large (left) or small holes or slots (right ) is shown. WAY (E) FOR CARRYING OUT THE INVENTION

FIG. 1 shows a perspective view of a sound-absorbing element. A carrier layer 1 has through holes 11. The carrier layer 1 is for example bent, corrugated, plate-shaped or shaped in another way. The carrier layer 1 comprises, for example, a wood, a wood material, a chipboard, an Oriented Strand Board (OSB), a medium density fiberboard (M DF plate), a high density fiberboard (HDF), a hardboard, a plywood board, an organically bound, in particular cement-bonded chipboard or another material. The carrier layer 1, which in particular has a dimensionally stable and torsionally rigid construction, has a thickness of 5 mm to 40 mm in one embodiment. The through openings 11 which extend from one side of the carrier layer 1 to the other side are, for example, circular in FIG. 1 and are drilled, for example, into the carrier layer 1. In one embodiment, the through holes have a diameter of 2mm to 1 0mm and the distance between the edge of the openings is for example 4mm to 48mm. In one embodiment, the through-openings 11 are slot-shaped and, for example, are milled or cut into the carrier layer 1. In one embodiment, the slots have a width of 2mm to 8mm and the distance between the edge of the slots is for example 5mm to 30mm. As shown schematically in Figure 1, the through openings are arranged for example in a regular grid. The ratio of the sum of the cross-sectional areas of the continuous openings to the area of one side of the carrier layer, ie the so-called open area, is for example 3% to 30%. As shown in FIG. 1, one or two cover layers 2, 2.2 are arranged on one or both sides of the carrier layer 1. The cover layers 2, 2.2 have a micro-perforation 21. For reasons of better clarity, the microperforation 21 in the cover layer provided with the reference numeral 2 in FIG. 1 is only partially shown and the microperforation of the cover layer provided with reference numeral 2.2 in FIG. 1 is not shown. The cover layers 2, 2.2 are designed, for example, plate-shaped and comprise a wood veneer, a wood material, a synthetic resin veneer, a plastic, a multi-layer resin-impregnated paper or other material. The cover layers 2, 2.2 have, in particular, an aesthetically desired coloring, grain, structure or another aesthetically desired property, for example on one or both sides. The micro-perforation 21 is formed in one embodiment by holes with a diameter of 1 .1 mm or less and a distance between the edges of the holes of 10 mm or less, wherein the micro-perforation 21 or the individual holes, the cover layer 2, 2.2 of a Penetrate side to the other side. The microperforation 21 is arranged, for example, in a regular grid. The ratio of the sum of the cross-sectional areas of the through openings of the microperforation 21 to the area of one side of the cover layer 2, 2.2, ie the so-called open area of the cover layer 2, 2.2, is for example in the range of 1% to 10%, preferably in the range of 1% to 7%. In one embodiment, the open area of the cover layer 2, 2.2 is less than 1%. The microperforation 21 of the cover layer 2, 2.2 is introduced in a variant by drilling, rolling, punching, a jet of water, a laser beam in the cover layer 2, 2.2.

As shown schematically in FIG. 1, one or two intermediate layers 3, 3.2 are arranged between the carrier layer 1 and one or both cover layers 2, 2.2. With the intermediate layers 3, 3.2, the cover layers 2, 2.2 are each connected to the carrier layer 1. In one embodiment, an intermediate layer 3, 3.2 is glued to the carrier layer 1. In one embodiment, the carrier layer 1 is produced together with one or both intermediate layers 3, 3.2, for example in a 3 D printing process, so that the carrier layer 1 and the intermediate layers 3, 3.2 consist of a single body or the intermediate layer 3, 3.2 to the carrier layer 1 is formed. In one embodiment, a cover layer 2, 2.2 glued to an intermediate layer 3, 3.2, which is already glued to the carrier layer 1 or is formed thereon. In one embodiment variant, a cover layer 2, 2.2 is glued to an intermediate layer 3, 3.2, and the composite of the cover layer 2, 2.2 glued together and the intermediate layer 3, 3.2 is glued onto the support layer 1. In one embodiment, a cover layer 2, 2.2 is produced together with an intermediate layer 3, 3.2, for example in a 3 D printing process, so that the cover layer 2, 2.2 and the intermediate layer 3, 3.2 form a single body, which then onto the carrier layer 1 is glued. In one embodiment, the cover layer 2, 2.2 is connected to the carrier layer 1 in a different manner via the intermediate layer 3, 3.2.

In one embodiment, one or both intermediate layers 3, 3.2 are formed such that a communicating connection is created between the microperforation 21 of the cover layers 2, 2.1 and openings 11 of the carrier layer 1 in order to produce a sound-absorbing effect. In an embodiment variant, an acoustic connection is created so that sound waves which penetrate through the microperforation 21 of a cover layer 2, 2.1 are guided through the corresponding intermediate layer 3, 3.2 through to the openings 11 of the carrier layer 1. In one embodiment, an intermediate layer 3, 3.2 has the function of a spacer, which creates a spacing of the cover layer 2, 2.2 of the support layer 1 and which the Sound pressure immediately after the microperforated cover layer 2, 2.2 on all sides, ie in the longitudinal direction, in the transverse direction and in the direction of the openings 1 1 of the support layer 1 passes, the sound of the intermediate layer 3, 3.2 of the micro perforation 21 of the cover layer 2 to the Openings 21 of the carrier layer penetrates. In one embodiment, an intermediate layer 3, 3.2 comprises a stable structure which is designed on the front side and the back side such that the intermediate layer 3, 3.2 can be fixedly connected to a cover layer 2, 2.2 and the carrier layer 1, wherein the intermediate layer 3, 3.2 ensures a stable and firm support of the cover layer 2, 2.2 on the carrier layer 1. In one embodiment, the intermediate layer 3, 3.2 comprises a three-dimensional shaped textile such as, for example, a woven fabric, a braid, a knitted fabric, a scrim or another textile. The three-dimensional shape of the textile on the one hand a stable mounting of the cover layer 2, 2.2 on the support layer 1 allows and on the other hand, the sound penetrating through the micro perforation 21 of a cover layer 2, 2.2, through the three-dimensional textile through to the openings. 1 1 of the carrier layer 1 out. In one embodiment, an intermediate layer 3, 3.2 comprises a textile which has nubs and a textile layer, a glass fiber material, a carbon fiber material, an aramid, a porous foam, in particular of glass, metal or ceramic, a stamped profile of metal or plastic with an embossment such as Pimples, diamonds, pyramids, grooves. All these materials have the property that on the one hand, for example, by bonding with a cover layer 2, 2.2 and the support layer 1, a stable support compound of the cover layer 2, 2.2 is created on the support layer 1 and on the other hand due to the porosity, the grooves, the foam inclusions , etc. For sound waves, a way is available so that there is a communicating connection for these microperforation 21 of a cover layer 2, 2.2 to the openings 1 1 of the support layer 1 and thus there is a sound-absorbing effect. In one embodiment, the intermediate layer 3, 3.2 a thickness of between 1 mm and 5mm, preferably 2mm, and is made of sustainable and durable material.

FIG. 2 shows a sound-absorbing element known from the prior art, which has a carrier layer 1 with through openings 11 and a cover layer 2 glued thereon with a microperforation 21. As shown schematically in FIG. 2, sound waves 4 strike the microperforation 21 of the cover layer 2. However, the microperforation 21 of the cover layer 2 is partially closed, since the support layer 1 does not always connect with openings 11 to the microperforation 21. Reflections 41 of the sound waves 4 result at the points at which the microperforation 21 is closed by the carrier layer 1, whereas at the points at which openings 1 1 adjoin the microperforation 21, penetrations 42 of the sound waves 4 result. As can be seen from FIG. 2, therefore, only part of the microperforation 21 is effective for sound absorption in the sound-absorbing element known from the prior art. However, an essential part of the microperforation 21 of the sound-absorbing element shown schematically in Figure 2 is not effective for the sound absorption and arise at these sites only reflections 41 of the sound waves 4. So that the entire micro-perforation 21 of the sound-absorbing element shown in Figure 2 is effective , the micro-perforation 21 has to be produced corresponding to the openings 11 of the carrier layer 1 and the cover layer 2 has to be aligned correspondingly to the carrier layer 1. However, this results in a complicated and expensive production.

FIG. 3 shows schematically the opening of a sound-absorbing element with a covering layer 2, a carrier layer 1 and an intermediate layer 3, which keeps the covering layer 2 at a distance from the carrier layer 1. As shown schematically in FIG. 3, For example, the intermediate layer 3 has conical nubs 31 which are mounted on a base layer 32. In an embodiment, the base layer 32 comprises a textile layer.

FIG. 4 schematically shows the plan view of an intermediate layer 3 of the sound-absorbing element according to FIG. 3. The intermediate layer 3 has conical nubs 3 1, which are fastened on the base layer 32. FIG. 4 schematically shows the microperforation 21 of the cover layer 2 and the openings 11 of the carrier layer 1.

As can be seen from FIG. 3 and FIG. 4, the dimples 31 are fastened on the base layer 32 at a distance from one another. Thus, there is a free space between the nubs 31, in which in particular sound waves can propagate.

The tips of the dimples 31 of the intermediate layer 3 are connected to the cover layer 2 and the base layer 32 is connected to the carrier layer 1, for example adhesively bonded. Thus, the cover layer 2 is connected to the carrier layer 1 via the intermediate layer 3.

FIG. 3 schematically shows penetrations 42 of sound waves 4, which penetrate into the microperforation 21 of the cover layer 2. As shown schematically in FIG. 4, the entire microperforation 21 of the cover layer 2 is available for penetrations 42 of the sound waves 4. This is possible because the microperforation 21 of the cover layer 2 is not closed by the intermediate layer 3. Although the knobs 31 of the intermediate layer 3 are attached to the cover layer 2. However, the dimples 31 are spaced and shaped such that, for geometrical reasons, the tips of the dimples 31 do not coincide with the microperforation 21 of the cover layer 2 or that such collapsing accounts for only a small percentage. The microperforation 21 of the cover layer 2 thus opens into the free space between the nubs Sound waves which penetrate into the microperforation 21 of the cover layer 2 are thus not reflected, but guided into the free space of the intermediate layer 3, which is located between the nubs 31 of the intermediate layer 3. The base layer 32, on which the knobs 31 are arranged, is permeable to sound waves, for example as a textile layer. Between the free space of the intermediate layer 3, which adjoins the through holes 1 1 of the support layer 1, and the openings 1 1 of the support layer 1 is thus a permeable to sound waves, communicating connection by the sound waves initially around the knobs around 31 in the Spread interlayer 3 and then penetrate through the textile layer 32 of the intermediate layer 3 into the openings 1 1 of the support layer 1. As a result, there is a communicating connection for producing a sound-absorbing effect between the microperforation 21 of the cover layer 2 and openings 11 of the carrier layer 1. In one embodiment, the open areas of the cover layer 2, 2.2 and the open area of the carrier layer 1 are matched to one another in order to achieve a desired sound-absorbing effect, for example in a specific frequency band.

In one embodiment, the carrier layer 1 has grooves, which connect the openings 1 1 communicating with each other, to provide an additional space in which sound waves 4 can propagate, in particular for communicating the micro-perforation 21 of the cover layer 2 with the openings 1 1 of Carrier layer 1. FIG. 5 shows a measurement of a sound-absorbing element having a cover layer with a microperforation, with a carrier layer with a plurality of through openings and an intermediate layer which holds the cover layer spaced apart on the carrier layer, the intermediate layer being designed to interpose a sound-absorbing effect the microperforation of the cover layer and openings of the carrier layer to create a communicating connection. FIG. 5 shows the sound absorption factor a _s as a function of the frequency f. The area of the test material is 1 2 m ² . The volume of the reverberation room is 21 2 m ³ . When the reverberation chamber is empty and the test material is located in the reverberation room, ie when the sound absorbing element is arranged, the relative humidity is 66%, the temperature is 9 ° C and the air pressure is 1 04.5kPa. The sound absorption factor a _s indicates how large the absorbed portion of the total incident sound is. a _s = 0 means that there is no absorption, the entire incident sound is reflected. At a _s = 0.5, 50% of the sound energy is absorbed and 50% reflected. At ct _s = 1, the entire incident sound is absorbed, ie reflection no longer takes place. As can be seen from FIG. 5, the sound absorption coefficient ct _s in the range from approximately 200 Hz to 1000 Hz is greater than approximately 0.75. Thus, the sound-absorbing effect of the sound-absorbing element in this area is particularly high.

The length-related flow resistance is given in kPa s / m ² , whereby the thickness of the sound-absorbing element is not taken into account. The length-related flow resistance influences the sound absorption and can be specified in particular for optimized sound-absorbing elements. Typically, values of 30 to 300 kPa s / m ^{2 are} to be expected. According to a further aspect, the invention relates to sound-absorbing elements in the form of microperforated sound absorbers having at least one intermediate layer formed by sound-permeable spacer between a microperforated cover layer and a perforated or slotted carrier layer, preferably in the form of a carrier plate. The cover layers can be arranged on both sides or on one side of the carrier layer. In the latter case, preferably a fleece and / or mineral fiber on the back, that is arranged on the side without a cover layer.

These embodiments of the invention enable a modular and further simplified production of the sound absorber with maximum sound-active perforation surface and maximum stability of the elements. By the spacer between the thin cover layer and perforated or slotted support plate as in the aforementioned intermediate layers for disturbing the viewer from the outside visible optical markings of the openings in the carrier layer can be avoided.

The new microperforated sound absorber functions as a microabsorber via the thin microperforated cover layer and the spacer to form a partially reverberant rear wall. These sound absorbers act in the unilateral embodiment also in combination with the deposited mineral fiber and / or the deposited nonwoven on the back of the sound absorber by a communicating connection of the perforations or slits in the support plate with the microperforations in the cover layer. The term micro-perforated sound absorbers in the prior art mostly bivalve components consisting of a perforated, grooved or slotted plate made of solid material such as wood, compressed wood, pressed board, metal, plastic or gypsum, in which on the view and or on the back microperforated films or thin sheets of laminate, wood, metal or plastic are arranged. A corresponding principle is described in European patent EP201 5291 and in published patent application DE 1 98 39 973 A1. In the case of microperforated absorbers with carrier plates of solid, solid material, a considerable proportion of the microholes has hitherto been covered by the closed surface of the carrier plate. The covered microperforations are lost for the absorber performance. As a result, the sound in this area is not absorbed but reflected. The effect of sound absorption in such micro-perforated sound absorbers is limited accordingly. In addition, in the production of such known sound absorbers, the microperforated cover layers and the perforated or slotted support plates are to be matched with regard to the above-described "loss ^" of microperforations in terms of open effective area.

The new microperforated cover layers are therefore connected to the intermediate layer, for example with the spacer, and the perforated, grooved or slotted carrier layer or plate in such a way that on the one hand the majority of the microholes can actively - not concealed - absorb the sound and On the other hand, the front and / or back cover layers plan, flat and pressure resistant can be used as an architectural design element. In the case of microabsorbers, a resonance room must be provided on the backside of the microperforated cover layer for the purpose of sound absorption. In the case of a multilayer absorber, moreover, the first and the following microperforated cover layers must be in contact with each other in terms of sound pressure through the support plate. Since the sound pressure, respectively the sound traverses the absorber in an undirected way, passages of cover layers and carrier plate can be displaced when using a spacers which are permeable on all sides. An important requirement for the microperforated sound absorber is the stability which is given by the solid support plate only if this support plate is only partially and preferably evenly distributed perforated, grooved or slotted. The architecture requires jointless large-sized sound absorbers. Stiffness suffers from delicate materials such as gypsum and intensively processed backing plates, resulting in a format limitation. The novel novel intermediate layers, for example in the form of the Abstanzhalter, and the full use of the microperforated cover layers maximum absorption while maximum stability of the sound absorber can be achieved. In terms of manufacturing technology, the microperforated cover layers and modularly processed carrier plates can be produced independently of one another. The intermediate layers, for example in the form of the spacers, are advantageously joined in a first operation with the microperforated cover layer, or according to a further embodiment intermediate layers, for example in the form of the spacers, are connected in a first step to the support plate. Subsequently, cover layer with intermediate layer / spacers are connected to the carrier plate or the intermediate layers previously connected to the carrier plate, for example in the form of the spacers, are connected to the cover layer. For architectural reasons, materials and surface treatment are preferably selected so as to avoid light reflections between the microholes of the cover layer and the processed support plate.

In order to achieve high sound absorption in all frequency ranges, the sound must be able to penetrate the absorber in a high proportion and be converted into heat in the small holes or slots by friction. By the today's processing of the solid carrier plates in form of holes, grooves or slits become too many micro holes covered by the closed part of the carrier plate and therefore inactive. To counteract this disadvantage, the support plate must be worked more intensively. As a result, however, the stability of the entire sound absorber is greatly reduced, the absorber is expensive due to the complex processing and a subsequent format change is difficult to impossible. A direct bond, for example by a direct bonding, including resonance space between a thin microperforated cover plate and a coarsely perforated or slotted support plate requires a coordination between the open hole surfaces, this makes impossible a modular structure of microperforated cover layer and machined support plate. The direct connection of cover layer and support plate with different perforations (micro perforation in the cover layer and large-format perforation, grooving or slitting) also causes disturbing light reflections on the visible side of the absorber, especially in the case of colored surfaces.

The intermediate layer, for example in the form of a spacer, between microperforated cover layers and solid support bodies offers significantly more open microholes for sound absorption and transmission. The sound pressure is less reflected by the increased open area of the top layer surface and absorbed by the micro perforation to a greater extent. For optimal dissipation of the sound level, ie the conversion of sound energy into heat energy, the length-related flow resistance can be optimized by the open effective area in the support plate. Experiments have shown that with less open effective area in the support plate and corresponding maximum effective area, ie by the micro perforation generated open area in the microperforated cover layer with these new sound absorbers with intermediate layer, preferably with spacer, good absorption values be achieved. Furthermore, the flow resistance can be optimized by the incorporation of sound-absorbing material.

The installation of a sound-permeable spacer reduces the number and open area of the openings in the substrates, thus improving stability, especially for delicate materials with low intrinsic stability such as gypsum. As a result, even relatively large sound absorbers can be manufactured and installed quickly and inexpensively with less effort. A direct coordination between cover layers and carrier plates with respect to the positioning of the openings to achieve a continuous open hole area is no longer required by the spacer. Support plates made of different materials can be produced modularly and independently of the cover layer and connected together in a temporally and if necessary axially spaced step.

Furthermore, a stable uniform structure is achieved by the intermediate layer, in particular by the spacer between the microperforated cover layers and the carrier surface, and the desired distance between the two layers is set, thereby on the one hand on the back of the microperforated cover layer of the required for sound absorption cavity space provided and In addition, disturbing optical light reflections are avoided. The intermediate layer, for example in the form of a spacer, may also include additional functions such as heat absorption with energetic storage.

Material selection for spacers and construction variants According to preferred embodiments of the present invention, spacers are arranged directly between the microperforated cover layers and the carrier layer, which can be penetrated unhindered by the sound pressure. The preferred spacers are sturdy and designed to be flat on the front and back. Suitable are all types of spacers which are connected to the microperforated cover layer and with the support plate, preferably glued, can be. A suitable spacer is thicker than 0.8 mm, preferably between 1 .00 to 3 .00 mm, advantageously 1 .5 to 2 .00 mm thick, and is made of durable and durable material. The following materials may be used for the spacers: a) 3 D textiles such as woven, braided, knitted, laid, knotted fibers, in glass, carbon fiber materials and aramids; b) open porous foams of glass, metal or ceramic; c) stamped dimpled, square, route, pyramid, groove embossing of metal or plastic.

According to further embodiments of the invention, the following materials are suitable for the spacers: d) honeycomb discs - preferably cut - of paper, cardboard, aluminum or aramid. According to preferred embodiments, the microperforated absorbers according to the invention have the following structure. A spacer is adhered to the underside of a microperforated cover layer or else to an upper and / or underside of the carrier layer, preferably a carrier plate.

In a separate step, the carrier plate is perforated or slotted according to a modular grid so as to achieve an open area of 26% to 40% in the carrier plate. It is clear to the person skilled in the art that this processing of the carrier plate takes place before the intermediate layer, for example in the form of a spacer, is glued onto the carrier plate. The cover layer is preferably perforated in a first step and then connected to the spacer, preferably by means of gluing, with a glue layer preferably applied to the spacer.

While a microperforated cover layer is always arranged on the visible side of the sound-absorbing elements or absorbers according to the invention, a second microperforated cover layer can be applied on a second spacer or another intermediate layer or a sound-absorbing nonwoven and / or mineral fiber plate on the reverse side, depending on the intended use become.

According to preferred embodiments, the spacers according to the invention are preferably produced from honeycomb materials. The difference between honeycomb material and the aforementioned materials for creating the intermediate layer such as knobs is very low in terms of function. The free communicating connection between the microperforated cover layer and the back absorption through a microperforated covering layer, nonwoven or mineral fiber via the openings in the carrier layer is determined by the intermediate layers according to the invention approximately for all openings. achieved in the cover layer. In the embodiments with spacers, for example in the form of a honeycomb material, this advantage continues to exist, even if here no longer any opening in the covering layer is in communicating connection with each opening in the carrier layer, for example the carrier plate. For the most part, the sound pressure seeks the path with the least resistance, and therefore for the most part, the communicating connection between micro perforation openings and openings directly beneath it in the support plate, and only to a small extent a further path in the longitudinal and transverse direction within the intermediate layer. Although the sound in the honeycomb spacers according to certain embodiments is not available in the longitudinal and transverse directions within the intermediate layer, for a sufficient portion of the microperforation apertures in the cover layer, a communicating connection is made through the apertures in the backing layer to the back side of the cover layer Absorbers provided. The spacers also ensure that almost all of the microperforation apertures in the cover layer are open and the resonant cavity necessary for sound absorption is available on the back side of the microperforated cover layer. A very good sound absorption is achieved with absorbers with intermediate layer, for example with spacers, if: i) the open hole area in the carrier plate is 20% to 40%, preferably 30%, ii) the height of the spacers, preferably the honeycomb structure as spacer 1 .0 mm to 3.0 mm, preferably 2.0 mm, and iii) the cell width of the honeycomb is 3.0 mm to 1 0.0 mm, preferably 3.4 mm to 4.8 mm, this cell width being dependent on whether the cover layer material is soft or hard. The absorption performance is also influenced by the design of the open area in the carrier layer, for example the diameter and the arrangement of the perforation in the carrier plate. Preferably, an open hole area of 26 to 40%, more preferably of 30% is selected. Preferred materials for making honeycomb spacers are: paper, cardboard, aramid (Nomex aramid), aluminum. A preferred honeycomb form is the hexagonal, although rectangular, square, round and any other types of honeycomb can be used.

FIG. 6 schematically shows the construction of a sound-absorbing element according to the invention with a honeycomb-shaped spacer 33. The visible side of the absorbent element is formed by a micro-perforated cover layer 2. This is glued to the honeycomb spacer 33, which keeps them stable and exactly plane-parallel to the surface of the support plate 1 2 at a distance of 2 mm. The honeycomb structure ensures that in each case a multiplicity of microperforation openings in the cover layer are in communicating connection with the bores 13 in the support plate and thus with the acoustical nonwoven 5 on the back side of the support plate. For the microperforation openings in the cover layer, which have no direct connection to a 1 3 in the support plate, the honeycomb structure forms the necessary for sound absorption resonance space on the back of the microperforated cover layer. In the figures 7, 8 and 9 concrete examples (masstabgetreu with Vermassung) of further embodiments of sound-absorbing elements are shown with honeycomb spacers. The essential mass of the perforation of the carrier plate are each indicated in the figure. According to an embodiment not shown in the figures, the cover layer is a 0.8 mm thick wood veneer with microholes of 0.5 mm diameter. More than 300,000 micro holes per square meter result in an open area of 6%. The spacer is an aramid reinforced paper honeycomb disk with a height of 1 .5 mm and a cell width of 3.2 mm with a density of 48 or up to 64 Kp / m ³ . The support plate made of MDF gypsum is provided with grid holes with 8.0 or 1 0.0mm hole diameter, resulting in a passage area of 30 or 40%.

According to another embodiment, not shown in the figures, the cover layer is a 0.8 mm thick wood veneer with microholes with a diameter of 0.2 mm. These microholes have been incorporated with a needle method in the preferably previously varnished veneer. More than 30000 micro holes per square meter result in an open area of about 1%. The spacer is an aramid reinforced paper honeycomb disk with a height of 1 .5 mm and a cell width of 3.2 mm with a density of 48 or up to 64 Kp / m ³ . The support plate made of MDF gypsum is provided with grid holes with 8.0 or 1 0.0mm hole diameter, resulting in a passage area of 30 or 40%.

Optionally, the back of the element may be provided with a second cover layer or a cushioning nonwoven material.

According to a further preferred embodiment, not shown in the figures, the carrier layer of the sound-absorbing element comprises a sandwich of a 1 6 - 20 mm thick gypsum fiber board and a silicate board glued to a composite or sandwich with a thickness of 1 .9 mm. The material of the silicate plate is, for example, palusol from BASF. The carrier layer is glued after bonding with a 1 6 mm to 1 6 mm holes with 1 0mm diameter. Subsequently, either a honeycomb structure made of aluminum or a glass nonwoven grid is adhered as an intermediate layer to which in turn a cover layer of microperforated (grid 1 .8 X 0.9 mm, hole diameter 0.5 mm) wood veneer or laminated fiber material is glued. Alternatively, a sandwich of cover layer and intermediate layer can be produced beforehand, which is then adhered to the perforated support layer.

In this embodiment, carrier layer materials and intermediate layer have a calorific value of 0 MJ / m ² , so that even in combination with a combustible top layer of less than 1 mm thickness in the finished product no substantial combustible layers are present. The silicate layer puffs up at temperatures as low as 200 ° C and acts as a shield to the fire or a heat source.

REFERENCE NUMBERS

1 0 sound-absorbing element

1 carrier layer

1 1 openings of the carrier layer

1 2 support plate

1 3 holes in the support plate

2, 2.2 cover layer

21 microperforation of the topcoat

3, 3.2 Interlayer

31 pimples of the intermediate layer

32 base layer of the intermediate layer

33 honeycomb spacer

4 sound waves

41 reflections of sound waves

42 penetrations of sound waves

5 Acoustic fleece a Micro-perforation hole spacing b Micro-perforation hole diameter d Sound-proof back panel thickness t Microperforated sheet absorber thickness

Claims

A sound absorbing member (10) comprising a resonator having a cover layer (2, 2.2) with a microperforation (21); a carrier layer (1) with a plurality of through openings (1 1) such as in particular holes or slits; and an intermediate layer (3, 3.

2), which keeps the cover layer (2) spaced from the carrier layer (1), wherein the intermediate layer (3,

3.2) is designed to create communicating connections for generating a sound-absorbing effect between the micro-perforation (21) of the cover layer (2) and openings (1 1) of the carrier layer (1).

The sound absorbing member (10) according to claim 1, wherein the cover layer (2, 2.2) comprises one or more of: a wood veneer, a wood material, a synthetic resin veneer, a plastic, a multi-layer resin impregnated paper, a metal foil, a metal plate.

The sound absorbing member (10) according to claim 1 or 2, wherein the support layer (1) comprises one or more of: a wood, a wood material, a chipboard, an Oriented Strand Board (OSB), a medium density fiberboard (MDF board), a high-density fiberboard (HDF board), a hardboard, a plywood board, an organically bonded particular cementitious chipboard, a gypsum board, a plasterboard, a honeycomb panel, a light metal plate, a plastic plate, resin, gypsum or plasterboard , Silicate or glass foam.

4. The sound absorbing member (1 0) according to any one of claims 1 to 3, wherein the intermediate layer (3, 3.2) comprises one or more of the following materials: a textile, in particular a three-dimensionally shaped textile such as a woven, braided, knitted fabric , Clutch; a textile made of knobs and fibers; a fiberglass material; a carbon fiber material; an aramid; a porous foam, in particular of glass, metal, ceramic; a stamped profile of metal or plastic with an embossment such as knobs, diamonds, pyramid, grooves or a honeycomb material of paper, cardboard, aramid, aluminum; Honeycomb discs - preferably cut - soaked in polyamide, paper, cardboard, aluminum and / or the aforementioned materials or impregnated with aramid.

5. The sound absorbing member (1 0) according to any one of claims 1 to 4, wherein the carrier layer (1) is plate-shaped.

6. The sound absorbing member (1 0) according to any one of claims 1 to 5, wherein the micro perforation (21) of the cover layer (2, 2.2) has holes with a diameter of 0.2 to 1 mm, preferably 0.5 mm and a mutual distance of 10 mm or less and / or the open area in the cover layer formed by the microperforation is 1 to 7%, preferably 6%.

7. The sound absorbing member (1 0) according to any one of claims 1 to 6, wherein the carrier layer (1) has through openings (1 1) having a diameter of 4mm or more, preferably from 8mm to 1 0 mm and a mutual distance of 2mm or more, preferably from 2 to 4mm.

8. The sound-absorbing element (1 0) according to any one of claims 1 to 7, wherein on two opposite sides of the carrier layer (1) each have an intermediate layer (2, 2.2) are provided, each having a cover layer (2, 2.2) spaced on the Carrier layer (1) stops.

9. The sound-absorbing element (1 0) according to any one of claims 1 to 4, wherein the carrier layer (1) has two opposite sides and the intermediate layer (3, 3.2), which the cover layer (2, 2.2) spaced on the carrier layer (1 ) is provided on one of the sides of the carrier layer (1) and on the other side of the carrier layer (1) one or more of the following materials is attached: a nonwoven, a glass fiber mat, a foam, a filler, an insulating material.

10. The sound absorbing member (1 0) according to any one of claims 1 to 9, wherein the intermediate layer has a thickness of between 1 mm and 5 mm, preferably 1 mm to 3 mm and preferably 1 .5 to 2 mm.

1 1. The sound-absorbing element according to one of claims 1 to 1 0, characterized in that between the intermediate layer and the cover layer, a flame retardant layer is arranged.

12. The sound-absorbing element according to claim 11, characterized in that the flameproofing layer is arranged on the rear side of the cover layer and the microperforation is mounted in the composite of flameproofing layer and covering layer, or in that the flameproofing layer is arranged on the backside of the covering layer and comprises a fleece ,

13. The sound-absorbing element according to one of claims 4 to 1 0, characterized in that the intermediate layer comprises a honeycomb material, which is made of flame retardant material, flame retardant material comprises or the honeycombs are filled with sound-transmitting flame retardant material.

14. A composite of a cover layer (2, 2.2) with a microperforation (21) and an intermediate layer (3, 3.2), which is connected to the cover layer (2, 2.2), wherein the intermediate layer (3, 3.2) for the communicating Connection with an openings (1 1) having carrier layer (1) is formed, wherein the cover layer (2, 2.2) is arranged to produce a sound-absorbing effect of one of the cover layer (2, 2.2), the intermediate layer (3, 3.2) and the carrier layer (1) formed sound-absorbing element (1 0) between the micro-perforation (21) of the cover layer (2, 2.2) and openings (1 1) of the carrier layer (1) to create a communicating connection.

The composite of claim 14, wherein the cover layer (2, 2.2) comprises one or more of the following materials: a wood veneer, a wood material, a synthetic resin veneer, a plastic, a multi-layer resin impregnated paper.

16. The composite according to claim 1 4 or 1 5, wherein the intermediate layer (3, 3.2) comprises one or more of the following materials: a textile, in particular a three-dimensionally shaped textile such as a woven fabric, mesh, knitted fabric, scrim; a textile made of knobs and fibers; a fiberglass material; a carbon fiber material; an aramid; a porous foam, in particular of glass, metal, ceramic; a stamped profile of metal or plastic with an embossing like for example, pimples, diamonds, pyramids, grooves; Honeycomb discs - preferably cut - made of paper, cardboard, aluminum and / or aramid.

The composite according to one of claims 14 to 16, characterized in that the cover layer and / or the intermediate layer comprises a flame retardant material or that a flame retardant layer is arranged between the cover layer and the intermediate layer.

Method for producing a sound-absorbing element (10), wherein a cover layer (2, 2.2) having a microperforation (21), a carrier layer (1) having a plurality of through openings (11) such as in particular bores or slits and an intermediate layer (3, 3.2) , which holds the cover layer (2, 2.2) at a distance from the carrier layer (1), the intermediate layer (3, 3.2) being designed to generate a sound-absorbing effect between the microperforation (21) of the cover layer (2, 2.2 ) and openings (11) of the carrier layer (1) to create a communicating connection.