The present invention relates to a soundproofing or sound-absorbing material of an essentially flat structure exhibiting microslits therein. Said material is designed for manufacturing soundproofing or sound-absorbing objects or their precursors. The invention furthermore relates to a preferred method of manufacturing such materials.
Soundproofing or sound-absorbing structures, referred to in the following as “sound absorbers” for short, are used in many different fields to minimize disruptive noises. Sound absorbers have become necessary because human hearing is sensitive and can be damaged by excessively strong sound pressure or even by certain sound frequencies; loud noises or sounds at certain frequencies, even far below the damage threshold, are perceived as disturbing and impair the quality of life.
Sound absorbers as such are already known in the most diverse embodiments. For example, they can be a structure made from fibers, open-cell polymer foams, glass fiber mats, or sprayed-on layers (usually of polyurethane foam) or acoustic tiles. The noise-reducing effect of fibrous sound absorbers is based on a frictional distribution of the sound energy, which is in turn based on air pressure variations within the fibrous structure. Despite the advantages of broadband absorption of sound by these fibrous or foam structures, they also exhibit unpleasant disadvantages, namely the dislodging of particles which have broken off and the atmospheric pollution resulting therefrom. Therefore, the use of such sound absorbers is often very limited.
In recent years, another type of sound absorber has become known, namely perforated solid panels. These sound absorbers usually exhibit relatively thick perforated substrates, for example of metal, and the perforations consist of relatively large holes; i.e. with a diameter greater than 1 mm. Two types of these panel-like sound absorbers are generally used, namely those comprising a sound-reflecting surface and absorbing a narrow sound frequency band in the audible range, and others as mechanical and absorbent support for a fibrous sound absorber over a wide frequency spectrum. In this case, the perforated panels serve as a support structure and the fibrous materials function as sound absorbers.
Microperforated structures have also already been proposed as sound absorbers. Such structures (see the U.S. Pat. No. 6,194,052 B1 and WO 2006/101403 A1 documents) take the form of perforated or slit panels, are relatively thick (for example thicker than 2 mm), and provided with mechanisms (reinforcements, beads, etc.) to prevent vibrations from the acoustic waves. A microperforation in the sense of present-day technical practice refers to the diameter or width of the perforation being within a range of 0.05 to 0.5 mm (iVT International 2005, p. 105-107 and WO 2006/101403 A1; 0.01 to 0.8 mm according to U.S. Pat. No. 6,194,052 B1).
For example, the U.S. Pat. No. 5,700,527 patent specification describes a sound-absorbing component made of glass or synthetic glass having a thickness of 0.2 to 30 mm and perforations having a diameter of 0.1 to 2.0 mm arranged at a 2 to 20 mm spacing from one another. These panels are to be disposed on the walls, ceilings or doors of buildings to serve as sound absorbers.
It has now been found that the manufacture of microperforated structures to act as sound absorbers is difficult and costly. In the U.S. Pat. No. 6,194,052 document, the individual perforations are not punched out as microslits but instead pressed out of the material using press tools, which leaves behind edges. The sound-absorbing panels according to the WO 2006/101403 document are cut out using a laser tool; this method is however limited to specific materials (metals, etc.). It is alternatively proposed to adjacently arrange a plurality of very narrow panels at a distance corresponding to the width of the microslits; this option is of course excluded in practice.
Important during manufacture is producing holes having smooth edges; when the edges are not smooth, as can be observed for example in the case of perforating metal or plastic sheets, the sound-absorbing effect suffers. A special machine is also required to perform the perforating, which increases the manufacturing costs. Nor is it possible to provide microperforations in fibrous structures as already being used as sound absorbers.
The invention is based on the task of overcoming the disadvantages of known microperforated structures, regardless of whether they are panels or films of any of the most diverse materials, and providing a new, economically-produced and highly sound-absorbing material which can be used as such or, after the appropriate configuring, as a sound absorber.
The inventive material is defined in the first independent claim and a preferred method for its manufacture forms the object of the second independent claim. Preferred or specific embodiments are set forth in the dependent claims.
The term “essentially flat structure” as used in this document refers to a two-dimensional expansion, as present for example in most textile materials, but which can also be undulating and exhibit peaks and valleys without losing its overall impression of flatness.
The term “inhomogeneous” as used in this document refers to a structure composed of at least two different source materials or having different visual and/or structural properties in the longitudinal and transverse directions and in particular differing from film or panels.
The inventive sound-absorbing material is a textile, a mesh or any other material consisting of at least two different source materials. The difference can be based on the material itself and/or its dimensions and/or forms. It has been found that sound-absorbing effect increases with increasing hardness to the components of the inventive material. For example, glass fibers or metal fibers are well suited as source materials. But all source materials which are in the form of filaments or fibers, or which can be brought into such form, and made from all suitable natural or synthetic materials including metals, a listing of which would be far too exhaustive here, can be used.
The inventive material is generally manufactured by weaving or interlacing, wherein the source material is to be selected on the one hand such that the desired microslits form in the course of the manufacturing process and, on the other, other unwanted perforations are either not produced or can be eliminated. This approach calls for suitably selecting the source materials. In the process, the invention excludes using the same source materials; thus no inventive materials can be obtained by normal weaving using identical warp and weft fibers since no microslits can be formed in this way, rather either no through-holes whatsoever form in tightly-meshed textiles or quasi-square holes form in normal or loosely-meshed materials.
For example, flat filaments of relatively low flexibility can be used as warp threads and coalesced into textile surface structures by means of thin, flexible fibers or filaments serving as weft and incorporated at a distance from one another. The horizontal spacing of the warp filaments, which at the same time define the width of the microslits, is determined by the thickness of the weft fibers or filaments, and the spacing between two successive weft fibers or filaments then corresponds to the length of the microslits. Devices for manufacturing such mesh-like structures are known; machines already in use could easily be adapted to the requirements of manufacturing the new material.
The above remarks clearly indicate that the inventive material is extremely simple and economical to manufacture compared to the prior art methods.
If desired, the inventive material can undergo processing prior to, during or subsequent to manufacture. This would include finishing same so as to increase the sound-absorbing effect, fire-retardant finishings, preservative agents, dyes, anti-corrosive agents for metallic materials, light stabilizers, curing agents for setting the material structure and many others known to experts in this field. Of course deforming the flat material manufactured is also among the possibilities, for example into sound-absorbing molded parts for automobiles, airplanes, ships, etc. or into other three-dimensional structures such as corrugated matting, reed matting, etc.
Most of the dimensions of the new material can vary over a wide range. The length and width of the inventive structure are only limited by the possibilities afforded by the respective manufacturing equipment. The thickness of the material is regulated by the required stability. When preferably rigid, break/tear-resistant lead fibers or filaments are to be employed, as is preferred for the better soundproofing of such materials, one obtains a quite thin but yet firm structure, generally having a thickness amounting to between 1 and 10 mm, preferably 1 to 5 mm. It is however thoroughly conceivable to also manufacture thinner materials.
When necessary, thin inventive materials can be affixed or mounted to supporting structures. The dimensions of the inventive material's microslits are between 1 and 20 mm in length and between 0.01 and 0.4 mm in width, whereby occasionally exceeding these values is also within the inventive scope.
In terms of a structure which is also mechanically resistant, the longitudinally-extending components should be as rigid as possible and barely undulated, while the transverse components are thinner and more flexible and wrap around the longitudinal components. That means that the microslits are to run as linearly as possible. Yet the microslits can of course also run in any desired direction such that the present invention is by no means limited to just linear microslits. To this end, at least a 5:1 thickness ratio of longitudinal to transverse components is preferred, more preferable is (5-10):1.
When manufacturing the new material, unwanted openings or holes can occur, as usually do in loosely-woven textiles, should the source materials allow it. These holes are called parasitic holes. They interfere with the absorption of sound and are generally eliminated by simply pressing the material between pressure rollers, the surface of which can also be structured. A condition here is compressibility of the fibers or threads used; if the new materials are to be produced with correspondingly-adapted profiled fibers or filaments, no parasitic gaps will develop.
The invention will now be described in greater detail using embodiments referencing the drawings.
The drawings show:
For example, the width 14 of filaments 12 amounts to 5 to 10 mm and the interspacing 16 between two consecutive filaments is likewise 5 to 10 mm. However, completely different dimensions are also possible in conjunction hereto. The material of profiled rod 10 can be a thermoplastic material and the filaments 12 can be composed of glass fibers.
The microslits 22 are distributed evenly and throughout the depicted areal mesh. However, other embodiments seeking a non-uniform distribution of the microslits across the mesh are also conceivable.
The structure according to
Finally,
The inventive material can be directly used, e.g. to manufacture sound-absorbing curtains, etc. Moreover, a high absorption of sound can be ensured with a very thin layer; in contrast hereto, the general rule with conventional acoustic insulating elements is the thicker, the better.
The embodiments of the invention discussed and depicted are only examples serving for a better understanding and do not limit the invention which is solely defined by the scope of the claims. Many improvements and further developments are possible and readily lend themselves to one skilled in the art. It is thus evident that using different materials in the manufacture will enable different dimensions and different profiles to the rods, filaments and fibers and enable other parameters to be appropriately selected so as to adapt the inventive materials and structures to many applications, a listing of which would be far too exhaustive here. The invention can be used wherever it is desired or necessary to diminish existing or expected noise emissions or reduce them to an inaudible level.
Number | Date | Country | Kind |
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09161567.4 | May 2009 | EP | regional |