HYGIENE ABSORBENT AND USE OF A PLASTIC FOIL IN THE ABSORBENT

Abstract: A hygiene absorbent, i.e. a substantially liquid and gas tight sound absorbent, including an underabsorbent (11), a tight foil (13) and gas-filled blisters (15) located therebetween. Preferably a supporting layer (16) is located outside the under-absorbent to support the blisters (15).

Description: HYGIENE ABSORBENT AND USE OF A PLASTIC FOIL IN THE ABSORBENT' The present invention concerns a hygiene absorbent. Thereby is meant a substantially liquid and gas tight sound absorbent. For reduction of airborne disturbing noise in premises, free hard surfaces are generally provided with a suitable sound absorbent. In most cases an air-permeable absorbent of e.g. mineral wool is used. A great variety of such con¬ ventional absorbents having good acoustical absorption abi¬ lity is commercially available. They can at need be provided with a protective surface layer of air-permeable material, e.g. staple fibres, woven material, perforated sheet metal etc., without the sound absorbing ability being appreciably varied. In those cases where there is a requirement to e.g. fluch water in order to clean a room, e.g. premises for handling food products, absorbents must be provided with a tight facing layer, e.g. of plastic or aluminum foil, which should have a smooth surface in order to reduce the risk of hiding- places for dirt and microbes and in order to be readily cleanable. Such a facing layer, however, causes a substan- tial declination of the absorption ability of the absorbent. This is true within the whole frequency range from 100 Hz to 4000 Hz. Especially in the lower frequency range, i.e. fre¬ quencies below 500 Hz, the absorption ability becomes insig¬ nificant. An absorbent with a facing layer of the kind stated furthermore provides poor resistance against mechanical in¬ fluence. The demand for hygiene absorbents is great on the market. This is especially the case in the food products field, such as dairies, catering kitchens, dining halls etc., but also in other fields where the hygiene requirements are not the essential. This can be the case in premises with high air humidity, e.g. turbine halls in power stations and the like, or premises where grease and dust rapidly clog mine¬ ral wool absorbents, e.g. at cleaning of machine parts with hot water or cOmpressed air. The object of the present invention is to provide a so OMPI called hygiene absorbent which has a high absorption abil within a wide frequency range and is provided with a tigh preferably water-proof, facing lyaer. The hygiene absorbe ability according to the invention shall have high absorp tion ability within the frequency range from 100 Hz - 400 be readily cleanable by e.g. flushing, have good mechanic resistance and be free from cavities (risk of colony of b teria) . These objects are achieved in that the hygiene absorb according to the present invention has been given the cha teristics of the annexed claims. The invention will now be described under reference t the accompanying drawings, wherein Fig. 1 is a perspectiv view showing a cut-out portion of a hygiene absorbent acc ding to the invention, Fig. 2 shows at a larger scale a cross-section through a preferred embodiment of the hygie absorbent according to the invention, Fig. 3 shows an exa le of a facing or covering layer. Fig. 4 shows a corner o a room provided with hygiene absorbents according to the vention and Fig. 5 shows a diagram from which the absorpt of the hygiene absorbent according to the invention appea in comparison with known absorbents. A hygiene absorbent according to the invention compri at least one under-absorbent 11.and a tight surface layer 12 resting on the under-absorbent 11 by means of gas-fill cushions or blisters 15 (Fig. 1) . The under-absorbent 11, which may be a conventional mineral wool absorbent or the like, shall have such firm surface that the cushions 15 without appreciably sinking into the absorbent rest again said surface. Ordinary absorbents generally have no such surface, and, therefore, according to the preferred embod ment of the invention shown in Fig. 2, a supporting layer is disposed on the under-absorbent 11 such that it suppor the surface layer 12. The supporting layer 16 is over sub stantially its entire area provided with bores 17 or is i any other way perforated, e.g. by comprising a net of sui OMPI able material or expanded metal. The distribution of the bores 17 or other perforations may be arbitrary, but is suitably - especially for manufacturing reasons - regular. The surface layer 12 suitably consists of a plastic foil 13 which at its under-side is connected to another plastic foil 14 such that distributed blisters 15 are formed. The whole aggregate 13, 14 may be of the known type used for packing fragile objects. As examples of configurations of the aggregate 13, 14 which haveturned out operating satisfacto- rily, such can be mentioned where the blisters had circular shape, their diameters were about 9-10 mm and about 25 mm, respectively, their centers were located at the angles of equilateral triangles having 11 mm and 28 mm side-length, respectively, and their heights (thicknesses) were 3 mm and 12 mm, respectively. The larger blisters were effective within a lower frequency range than the smaller ones. As an alternative to circular shape the blisters may be oval. Blisters having different diameters may alternatingly exist on one and the same surface layer 12. In such case, however, the height (thickness) of all blisters is suitably equal. The foil thickness is preferably 0.025 - 0.03 mm. The surface layer 12 may either lie loose against the supporting layer or be glued to same. As an alternative to the embodiment of the surface layer 12 shown and described a surface layer could be contemplated comprising the tight foil 13 and separate blisters or cushions, which are glued or otherwise attached to the foil 13. Such blisters do not either have to have equal size (have equal volume) , but the size may vary. As to some extent appears from Fig. 2 the perforation of the supporting layer does not have to correspond with the location of the blisters 15 or the spaces therebetween, but these relations may be entirely at random. The blisters may not, however, sink into the perforations, but must be supported by the supporting layer 16. The perforations, e.g. the bores 17, thus, may not have such wide openings that the OMPI Λ, WIPO . blisters 15 can be accomodated therein. The thickness of the supporting layer - and expecially the height of the bores 17 or corresponding openings in for instance a net shall not exceed 1 mm. The supporting layer 16, which may be of sheet metal or other suitable material, is integral with, or, attache to the walls 18 and bottom 19 of a box-like coffer 20, in which the under-absorbent 11 is accomodated and which for instance may have the shapes that appear from Fig. 4, wherein several hygiene absorbents according to the inven tion are adapted onto two walls of a room. In this case the joints between the individual coffers 20 are sealed by e.g. tapeing or sealing strips. For free suspension from a ceiling a coffer is suitab on both sides provided with a perforated supporting layer 16 and a superposed surface layer 12. As appears from the diagram of Fig. 5, the hygiene ab sorbent according to the present invention provides consi rably better absorption than a commercially available hyg absorbent, and substantially as good absorption (not audi differences) as a pure mineral absorbent. OM

Claims: C L A I M S 1. A hygiene absorbent, including a sound absorbing ma¬ terial (11) and a tight surface layer (12) , c h a r a c ¬ te r e d n .that between the tight surface layer (12) and the absorbing material (11) are located a great number of spaced gas-filled cushions or blisters (15) . 2. Absorbent according to claim 1, c h a r a c t e ¬ r i z e d i that between the absorbing material (11) and the blisters (15) is located a perforated supporting layer (16) against which the blisters (15) rest. 3. Absorbent according to claim 2, c h a r a c t e ¬ r i z e d i n that the supporting layer (16) constitutes a wall of a coffer (20) , in which the absorbing material is accomodated. 4. Absorbent according to any of the preceding claims, c h a r a c t e r i z e d i n that the surface layer (12) comprises a tight foil (13) and adhering to the under-side thereof a foil (14) which forms the walls of the blisters (15) , 5. The use of a plastic foil product known per se, comp¬ rising a smooth foil (13) and a blistered foil (14) , which between the blisters (15) is tightly attached to the smooth foil, in a hygiene absorbent according to any of the preceding claims.

Inventors: HAGBJER GUNNAR, HAGBJER G
Applicants: HAGBJER G, IFM AKUSTIKBYRAN AB
Application year: 1980
Main classification: E04B1
IPC codes: E04B1, G10K11