METHOD FOR PRODUCING A SOUND ABSORBING PANEL

Abstract

Method for producing a sound absorbing panel including the step of providing a predetermined amount of cellulose fibres. Cellulose fibres have an average length between 0.5 mm and 5 mm, preferably between 1.3 mm and 2.5 mm. The method further includes a step of soaking the cellulose fibres in a water basin to form a pulp and a step of depositing the pulp on a moulding die. The method further includes a step of pressing said the pulp in order to cause at least a partial removal of the water contained making a fibre mat. The method also includes a step of drying the fibre mat so as to cause evaporation of the water remained in the fibre mat making the sound absorbing panel.

Claims

1. Method for producing a sound absorbing panel, the method comprising the steps of: providing a predetermined amount of cellulose fibres, said cellulose fibres having an average length comprised between 0.5 mm and 5-mm, preferably said average length being comprised between 1.3 mm and 2.5 mm; soaking the cellulose fibres in a water basin to form a pulp; depositing said pulp on a moulding die; pressing said pulp in order to cause at least a partial removal of the water contained in the pulp making a fibre mat; drying said fibre mat so as to cause evaporation of the water remained in the fibre mat making said sound absorbing panel.

2. Method according to claim 1, comprising a step of adding at least one dye to the water basin so as to give a predetermined colouring to the pulp, said at least one dye being a natural dye.

3. Method according to claim 2, wherein said dye is a powder dye, preferably the dye having a particle size comprised between 20 ?m and 80 ?m.

4. Method according to claim 1, further comprising the steps of: collecting the water removed from the pulp during said pressing step; introducing the collected water into said basin.

5. Method according to claim 4, wherein, before the introduction step, the method comprises a step of purifying said collected water so as to remove said at least one dye.

6. Method according to claim 1, wherein said drying step takes place at a temperature comprised between 30? C. and 45? C.

7. Method according to claim 1, comprising, subsequent to said drying step, a step of applying, on at least one surface of said sound absorbing panel, an aqueous solution comprising a waterproofing element, preferably said waterproofing element being an acrylic product.

8. Sound absorbing panel made in accordance with the method claimed in claim 1, presenting a density value comprised between 100 Kg/m.sup.3 and 700 Kg/m.sup.3, preferably the density value being comprised between 150 Kg/m.sup.3 and 350 Kg/m.sup.3.

9. Sound absorbing panel according to claim 8, presenting a sound absorbing value comprised between 0.4 and 1 ?w.

Description

[0032] Such a description will be set forth herein below with reference to the accompanying drawing, provided for merely indicative and therefore non-limiting purposes, wherein:

[0033] FIG. 1 shows a diagram of the method according to the present invention.

[0034] The method for producing a sound absorbing panel F, according to the present invention, comprises a step of providing a predetermined amount of cellulose fibres.

[0035] According to an aspect of the invention, cellulose fibres have a length comprised between 0.5 mm and 5 mm.

[0036] Preferably, the average length of the cellulose fibres is comprised between 1.3 mm and 2.5 mm.

[0037] Advantageously, the length of the cellulose fibres used in the method according to the present invention makes the cellulose more easily processable.

[0038] Furthermore, the length of the cellulose fibres makes the sound absorbing panel F sufficiently rigid without the need to add binders and without the presence of lignin as is the case in the prior art.

[0039] Advantageously, the length of the cellulose fibres used in the method according to the present invention allows less water to be consumed in its processing, as will be described below.

[0040] Advantageously, the length of the cellulose fibres used in the method according to the present invention reduces the costs associated with the entire process because the cellulose is readily available.

[0041] The method further comprises a step of soaking the cellulose fibres in a water basin 100 to form a pulp P.

[0042] In this situation, the cellulose fibres are dispersed in water to form the pulp P.

[0043] According to a possible embodiment, the method comprises a step of adding at least one dye C to the water in order to give the pulp P a predetermined colouring.

[0044] In other words, if it is intended to give the final sound absorbing panel F a predetermined colouring, a dye C is added to the water basin 100 in which the cellulose fibres are soaked to form the pulp P so that the latter absorbs the dye C.

[0045] Preferably, the dye used is a natural type of dye, e.g. a mineral dye.

[0046] Preferably, the dye C is a powder dye with a particle size, for example, comprised between 20 ?m and 80 ?m.

[0047] Preferably, the dye C consists of kaolin and at least one additional component.

[0048] For example, iron oxide and manganese oxide can be mixed with the kaolin to give the kaolin a Sienna, i.e. red, colouring.

[0049] By way of example, calcium, manganese and iron carbonates can be mixed with the kaolin to give the kaolin a black colouring.

[0050] Advantageously, the use of natural dyes enables the production of coloured and, at the same time, safe sound absorbing panels F. In particular, natural dyes eliminate the problems resulting from possible harmful inhalation from formaldehyde-based resins used in the prior art.

[0051] In addition, the use of natural dyes lowers the environmental impact of the whole process of making the sound absorbing panels F as they are easy to dispose of and non-toxic.

[0052] The pulp P obtained from soaking the cellulose fibres in water is subsequently deposited on a moulding die 200.

[0053] Preferably, the moulding die 200 has a cross-section having the shape intended to be given to the final sound absorbing panel F.

[0054] Following the distribution step, the method comprises a pressing step of the pulp P such as to cause at least partial removal of the water contained therein and to create a fibre mat T.

[0055] In other words, during the pressing step, the pulp P is crushed and squeezed in such a way as to remove the water incorporated therein and in such a way as to give the pulp P the shape desired for the final sound absorbing panel F.

[0056] By way of example, FIG. 1 shows a press in which the lower half-mould is the moulding die 200 and in which an upper half-mould is moved closer to the lower half-mould to press the pulp P and make the fibre mat T.

[0057] According to a possible embodiment, the method comprises a step of collecting the water from the pressing step.

[0058] In more detail, during the pressing step, when the water contained in the pulp P is expelled, it is collected, e.g. in a receptacle 300. In this situation, the method comprises a step whereby the collected water is fed into the basin 100 for making a further sound absorbing panel F.

[0059] In other words, the water from the pressing step is collected and used again as water for soaking the cellulose fibres to make a further sound absorbing panel F.

[0060] Advantageously, through the collection and intake step, 90% of the water used for making a sound absorbing panel F can be recovered.

[0061] In the event that during the soaking step a dye C was added, the water resulting from the pressing step also contains therein part of the dye C. In this situation, the method comprises, prior to the intake step, a step of purifying the water collected in order to remove the dye C contained therein.

[0062] Advantageously, the use of natural dye C, and in particular powder dye, allows the water resulting from pressing to be re-used even if it had been coloured in the soaking step.

[0063] Moreover, even if the water was not reused, its disposal would be easy (through a simple decanting process) and not harmful to the environment as the dye C is natural.

[0064] Following the pressing step, the pulp P is squeezed to remove the water and deformed to form a fibre mat T.

[0065] In this situation, the method includes a step of drying the fibre mat T in such a way as to cause evaporation of the water remaining in the fibre mat T itself by making the sound absorbing panel F.

[0066] Preferably, the drying step takes place at a temperature comprised between 30? C. and 45? C.

[0067] Advantageously, drying the fibre mat T at such temperatures avoids the use of drying ovens and the like, significantly reducing the associated energy consumption.

[0068] At the end of the drying step, according to an embodiment of the method, the method comprises a step of applying an aqueous solution containing a waterproofing element to at least one surface of the sound absorbing panel F.

[0069] Preferably, the waterproofing element is an acrylic product.

[0070] According to a possible embodiment, this waterproofing element is coloured.

[0071] The aqueous solution may also contain other elements that can guarantee particular technical performance to the panel F, such as, for example, water-soluble fireproofing elements.

[0072] Advantageously, the application of the aqueous solution prevents the sound absorbing panel F from being damaged if placed in contact with water or moisture.

[0073] A sound absorbing panel F made in accordance with the method described above is also the subject matter of the present invention.

[0074] The sound absorbing panel F thus produced has a density value comprised between 100 Kg/m.sup.3 and 700 Kg/m.sup.3, preferably comprised between 150 Kg/m.sup.3 and 350 Kg/m.sup.3.

[0075] The resulting sound absorbing panel F has a sound absorbing value comprised between 0.4 and 1 aw.

[0076] Advantageously, the sound absorbing panel F made using the method described above is entirely recyclable as it does not contain any glues, solvents, resins or any other non-natural and toxic materials/substances.

[0077] In other words, the sound-absorbing panel F made by the method described above can, if for example damaged, be soaked again in water to form a new pulp P in order to repeat the steps of the method until a new sound absorbing panel F is formed.

[0078] The present invention achieves the intended purposes overcoming the drawbacks of the prior art.

[0079] The use of cellulose fibres with a length in accordance with the above allows the use of less water than known methods and facilitates the distribution of the pulp P on the moulding die 200.

[0080] Advantageously, the fact that no glues and/or synthetic dyes are used makes it possible to reuse the water resulting from the pressing of the pulp P, reducing waste and the associated cost.

[0081] Furthermore, the fact that no adhesives and/or chemical dyes are used makes both the manufacturing process and the use of the sound absorbing panel F safe for health.

[0082] The method also reduces the energy consumption of the entire process for making the sound absorbing panel F. In particular, drying the sound absorbing panel F at the claimed temperatures avoids the use of energy-intensive kilns and dryers.