Stock material or miscellaneous articles – Structurally defined web or sheet – Nonplanar uniform thickness material
Patent
1980-12-31
1984-05-22
Epstein, Henry F.
Stock material or miscellaneous articles
Structurally defined web or sheet
Nonplanar uniform thickness material
181288, 428138, B32B 312
Patent
active
044501951
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a hygienic 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 conventional absorbents having good acoustical absorption ability 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. flush 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 substantial 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. frequencies below 500 Hz, the absorption ability becomes insignificant. An absorbent with a facing layer of the kind stated furthermore provides poor resistance against mechanical influence.
The demand for hygienic 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 that 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 mineral 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 called hygienic absorbent which has a high absorption ability with a wide frequency range and is provided with a tight, preferably water-proof, facing layer. The hygienic absorbent ability according to the invention shall have high absorption ability within the frequency range from 100 Hz-4000 Hz, be readily cleanable by e.g. flushing, have good mechanical resistance and be free from cavities (and the risk of colonies of bacteria).
These objects are achieved in that the hygienic absorbent according to the present invention has been given the characteristics of the annexed claims .
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described under reference to the accompanying drawings, wherein:
FIG. 1 is a perspective view showing a cut-out portion of a hygienic absorbent according to the invention,
FIG. 2 shows at a larger scale a cross-section through a preferred embodiment of the hygienic absorbent according to the invention,
FIG. 3 shows an example of a facing or covering layer,
FIG. 4 shows a corner of a room provided with hygienic absorbents according to the invention, and
FIG. 5 shows a diagram from which the absorption of the hygienic absorbent according to the invention appears in comparison with known absorbents.
A hygienic absorbent according to the invention comprises at least one under-absorbent 11 and a tight surface layer 12 resting on the under-absorbent 11 by means of gas-filled 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 against said surface. Ordinary absorbents generally have no such surface, and, therefore, according to the preferred embodiment of the invention shown in FIG. 2, a supporting layer 16 is disposed on the under-absorbent 11 such that it supports the surface layer 12. The supporting layer 16 is over substantially its entire area provided with bores 17 or is in any other way perforated, e.g. by comprising a net of suitable material or expand
REFERENCES:
patent: 798804 (1905-09-01), Kunz
patent: 3384199 (1968-05-01), Eckel
patent: 3415711 (1968-12-01), Chavannes
patent: 3812001 (1974-05-01), Ryan
patent: 3887031 (1975-06-01), Wirt
patent: 3948347 (1976-04-01), Rutledge
patent: 4076872 (1978-02-01), Lewicki
patent: 4356642 (1982-11-01), Herman
Epstein Henry F.
IFM Akustikbyran AB
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