Acoustic building panel for installation as sound-absorbing ceiling panel and / or sound-absorbing wall panel

Abstract

The invention relates to Acoustic building panel (0) for installation as sound-absorbing ceiling panel and / or sound-absorbing wall panel, wherein said acoustic building panel (0) is provided by a method comprising the steps: A1) providing a first support material (20) and a first binding agent (30); A2) providing a first mixture (50) by mixing said first support material (20) and said first binding agent (30); A3) forming a first layer (10) from said first mixture (50); B1) providing a second support material (2), a second binding agent (3), and an air-entraining agent (4); B2) providing a second mixture (5) by mixing said second support material (2), said second binding agent (3), and said air-entraining agent (4); B3) forming a second layer (1) from said second mixture (5) arranged on said first layer (10); and C) solidifying said first binding agent (30) and said second binding agent (3).

Description

[0001] Acoustic building panel for installation as sound-absorbing ceiling panel and / or sound-absorbing wall panel

[0002] The invention refers to an acoustic building panel for installation as sound-absorbing ceiling panel and / or sound-absorbing wall panel.

[0003] The invention lies in the field of building panels that are installed in interior rooms to influence the room's acoustics.

[0004] To influence the room's acoustics building panels can be installed on the ceiling and walls of the room or suspended from the ceiling. Acoustic building panels are known that absorb sound in order to reduce the echo inside the room and thus create a more pleasant ambience in terms of the room acoustics, for example a more quiet room.

[0005] In addition to the purpose of influencing the acoustics in a room, such acoustic building panels can also influence the visual room design, in particular via their surface finish. It is particularly important that the surface of acoustic building panels for installation on the ceiling or walls suitably blends into the room. For this reason, acoustic building panels with a particularly fine surface structure and low roughness are known. However, this comes with the disadvantage that a finer surface structure has a detrimental effect on the acoustic building panel's ability to absorb sound. For such acoustic building panels, the finer the surface structure, the more sound is reflected.

[0006] A specific type of acoustic building panels, so called wood wool panels, are known and these wood wool panels offer the possibility to easily control their surface finish. Wood wool panels use wood chips (shavings) or wood fibres of various widths as support material. These wood chips or wood fibres are mixed an mineral binding agent such as caustic magnesite. The resulting mixture is shaped according to the required board dimensions into a layer with appropriate length, width and thickness. After solidifying the binding agent, which can comprise a baking at elevated temperatures with or without additional pressing, a solid wood wool panel is provided. The surface finish of a wood wool panel can be adjusted by adapting the size of the wood chips or wood fibres. However, the smaller the size of the wood chips or wood fibres and therefore the finer the finish of wood wool panel surface is, the less is the capability of such a wood wool panel for absorbing sound, i.e. its sound absorption coefficient and noise reduction coefficient are diminished.

[0007] It is the objective of the present invention to overcome the disadvantages of the prior art and, specifically, to provide an acoustic building panel for installation as sound-absorbing ceiling panel and / or sound-absorbing wall panel that is efficient in absorbing sound and provides a fine surface finish.

[0008] This objective is solved by an acoustic building panel for installation as sound-absorbing ceiling panel and / or sound-absorbing wall panel according to the independent claim. The dependent claims concern advantageous aspects of the invention.

[0009] The invention comprises an acoustic building panel for installation as sound-absorbing ceiling panel and / or sound-absorbing wall panel, wherein said acoustic building panel is provided by a method comprising the steps:

[0010] A1) providing a first support material and a first binding agent;

[0011] A2) providing a first mixture by mixing said first support material and said first binding agent;

[0012] A3) forming a first layer from said first mixture;

[0013] B1) providing a second support material, a second binding agent, and an air-entraining agent;

[0014] B2) providing a second mixture by mixing said second support material, said second binding agent, and said air-entraining agent;

[0015] B3) forming a second layer from said second mixture arranged on said first layer; and

[0016] C) solidifying said first binding agent and said second binding agent.

[0017] The first binding agent and the second binding agent can comprise caustic magnesite. Solidifying said first binding agent and said second binding agent can comprise drying and / or baking at elevated temperatures, e.g. 180°C. The air-entraining agent can comprise a surfactant and has the effect that the permeability to air of said second layer (and therefore also of said acoustic panel as a whole) is enhanced by reducing its airflow resistivity. The so reduced airflow resistivity also leads to the technical effect that the capability of the acoustic building panel to absorb sound is enhanced. The capability of the acoustic building panel to absorb sound can be measured by the (weighted) sound absorption coefficient defined and measured as in ISO 11654 in the version effective on the filing date of this application and / or the noise reduction coefficient defined and measured as in ASTM C423 in the version effective on the filing date of this application.

[0018] According to a preferred aspect, said first support material is composed of first fragments having a (average) length in a range between 1 cm and 35 cm, preferably between 3 cm and 30 cm, more preferably between 5 cm and 25 cm. Said first fragments have a (average) thickness of at least 1 mm, preferably of at least 2 mm, more preferably of at least 3 mm. In addition or alternatively, said second support material is composed of second fragments having a (average) length in a range between 0.2 mm and 4 mm, preferably between 0.3 mm and 3 mm, more preferably between 0.4 mm and 2 mm.

[0019] The acoustic building panel can be installed as sound-absorbing ceiling panel and / or soundabsorbing wall panel in such a way, that the surface of the first layer is facing the ceiling or wall and the surface of the second layer is facing the room. The (average) length of the second fragments can be chosen to provide a smooth and fine surface finish, while the (average) length and the (average) thickness of the first fragments can be chosen independently from the length of the second fragments. The (average) length and the (average) thickness of the first fragments affects the density of the first layer and can therefore be chosen to ensure that the acoustic building panel is stable and lightweight. The (average) length of the second fragments can be measured as the (average of the) largest diameters of circles around the second fragments.

[0020] According to another preferred aspect, said first fragments and said second fragments comprise synthetic and / or organic chips, and / or said first fragments and said second fragments comprise synthetic and / or organic fibres. Preferably said first fragments and said second fragments comprise wood chips and / or wood fibres. Wood chips and / or wood fibres as first fragments and second fragments can be used to provide an acoustic building panel in the form of a wood wool panel. Wood wool panels can also provide the preferable additional effect of good thermal insulation and low production cost. According to a particularly preferred aspect, said second fragments have a (average) width in a range between 0.5 to 1.0 times the (average) length of said second fragments, preferably between 0.7 to 1 .0 times the (average) length of said second fragments, more preferably between 0.9 to 1 .0 times the (average) length of said second fragments. The (average) width of the second fragments can be measured as the (average of the) smallest diameters of circles around the second fragments. In this way the (average) shape of the second fragments is grain-shaped. The closer the (average) width is to 1.0 times the (average) length, the more spherical the (average) shape of the second fragments becomes and it becomes easier to provide a smooth surface finish.

[0021] According to an advantageous aspect, said second layer has a thickness of at least 3 mm, preferably at least 5 mm, more preferably at least 10 mm. In addition or alternatively, said first layer has a thickness of at least 10 mm, preferably at least 20 mm, more preferably at least 30 mm.

[0022] According to another advantageous aspect, said second binding agent is provided with at least 50 wt.%, preferably with at least 60 wt.%, more preferably with at least 70 wt.% of the total amount of said second mixture. This can ensure sufficient binding after solidifying said second binding agent and leads to a robust acoustic building panel.

[0023] According to a particularly advantageous aspect, said air-entraining agent is provided in an amount in a range between 0.1 wt.% and 2.0 wt.%, preferably between 0.1 wt.% and 1.5 wt.%, more preferably between 0.2 wt.% and 1.0 wt.%, of the amount of said second binding agent. This allows to decrease the airflow resistance and enhance the (weighted) sound absorption coefficient by providing a larger amount of the air-entraining agent and at the same time the amount of the air-entraining agent is not too large to impede sufficient binding after solidifying said second binding agent. In this way an acoustic building panel, in particular an acoustic wood wool panel in case the support materials comprise wood, can be provided that has a (weighted) sound absorption coefficient of at least aw = 0.6.

[0024] According to a preferred aspect, the amount by wt.% of said air-entraining agent is chosen such that the airflow resistivity of the acoustic building panel is in the range of 160000 Pa*s / m2to 45000 Pa*s / m2, preferably smaller than 120000 Pa*s / m2, more preferably smaller than 90000 Pa*s / m2, most preferably smaller than 80000 Pa*s / m2. For special purposes, the amount by wt.% of said air-entraining agent is chosen such that the airflow resistivity of the acoustic building panel is even smaller than 45000 Pa*s / m2. Due to the nature of wood wool, the airflow resistivity values of identically produced products, as well as those of different locations of a single sample, may scatter over a certain range. Accordingly, numbers of airflow resistivity values given in this document are to be understood as average values, preferably average values of at least 5 identically produced samples or 5 locations of one sample, respectively.

[0025] According to another preferred aspect, the solidified second binding agent comprises enveloping sections that are in direct contact with said second fragments, and wherein the amount by wt.% of said air-entraining agent is chosen such that open and / or closed cavities are formed continuously distributed inside said enveloping section of the solidified second binding agent. In this way the second binding agent becomes porous while solidifying.

[0026] According to a particularly preferred aspect, said cavities have a size, shape and distribution to be formed permeably interconnected within said solidified second binding agent or to be formed separated within said solidified second binding agent.

[0027] In the following, the invention is described in connection to drawings, where:

[0028] Fig. 1 shows schematically the manufacturing of a preferred acoustic building panel provided by a preferred method;

[0029] Fig. 2 is a schematic front view of the acoustic building panel from Fig. 1 ;

[0030] Fig. 3 is a schematic cross sectional view through the first layer and the second layer of the acoustic building panel of Fig. 2;

[0031] Fig. 4 is a detailed schematic cross sectional view through the second layer of the acoustic building panel of Fig. 3;

[0032] Fig. 5 is a detailed schematic cross sectional view through a second fragment and solidified second binding agent of Fig. 4; and

[0033] Fig. 6 is a detailed schematic cross sectional view through the first layer of the acoustic building panel of Fig. 3. Fig. 1 shows schematically the manufacturing of a preferred acoustic building panel 0 for installation as sound-absorbing ceiling panel and / or sound-absorbing wall panel provided by a preferred method.

[0034] In step A1) of the method a first support material 20 composed of first fragments 20a made from wood fibres having an average length of 5 cm and a first binding agent 30 comprising caustic magnesite were provided. Moreover, in step B1) of the method a second support material 2 composed of second fragments 2a made from wood chips having an average length of 1 mm, a second binding agent 3 comprising caustic magnesite and an air-entraining agent 4, which is a surfactant, were provided. The average length of the second fragments 2a is measured as the average of the largest diameters of circles around the second fragments 2a. Said second fragments 2a have an average width that is 0.5 times the average length of said second fragments 2a, where the average width is measured as the average of the smallest diameters of circles around the second fragments 2a. In this way the average shape of the second fragments 2a is grain-shaped.

[0035] In step A2) said first support material 20 and said first binding agent 30 were mixed to provide a first mixture 50 containing the first binding agent 30 in an amount of 75 wt.% of the total amount of said first mixture 50 and said first support material 20 in an amount of 25 wt.% of the total amount of said first mixture 50. This ratio ensures sufficient binding after solidifying said first binding agent 30 and leads to a robust acoustic building panel 0.

[0036] In step B2) said second support material 2, said second binding agent 3 and said air-entraining agent 4 were mixed to provide a second mixture 5 containing the second binding agent 3 in an amount of 75 wt.% of the total amount of said second mixture 5, said second support material 2 in an amount of 24.5 wt.% of the total amount of said second mixture 5 and said air-entraining agent 4 in an amount of 0.5 wt.% of the total amount of said second mixture 5. This ratio ensures to decrease the airflow resistance and enhance the weighted sound absorption coefficient of the acoustic building panel 0, while at the same time the amount of the air-entraining agent 4 is not too large to impede sufficient binding after solidifying said second binding agent 3.

[0037] In step A3) of the method a first layer 10 with a thickness of 19 mm is formed from said first mixture 50. In the given example the first layer 10 forms while pressing said first mixture 50 between a first conveyor 100 and a second conveyor 101. A second layer 1 with a thickness of 6 mm is formed from said second mixture 5 by arranging said second mixture 5 on said first layer 10 in step B3) of the method. In the given example this is performed by distributing and pressing said second mixture 5 with the second conveyor 101 onto the first mixture 50.

[0038] In step C) of the method said first binding agent 30 and said second binding agent 3 are solidified by baking in an oven 102 at elevated temperatures of 180°C for 20 min.

[0039] The so provided continuous acoustic building panel 0 is cut with a saw 103 into smaller individual acoustic building panels 0. Since the resulting acoustic building panels 0 are made from wood chips and wood fibres, the so provided acoustic building panel 0 is a wood wool panel. The airflow resistivity of accordingly provided acoustic panels lies in a range of 46000 to 75000 Pa*s / m2. One representative, so provided acoustic building panel 0 has a weighted sound absorption coefficient of aw = 0.65, a noise reduction coefficient of NRC = 0.65, and an airflow resistivity of 74500 Pa*s / m2.

[0040] Fig. 2 and Fig. 3 are described together in the following. Fig. 2 is a schematic front view of the acoustic building panel 0 from Fig. 1. Fig. 3 is a schematic cross sectional view along a cut A (c.f. Fig. 2) through the first layer 10 and the second layer 1 of the acoustic building panel 0 of Fig. 2.

[0041] The acoustic building panel 0 can be installed as sound-absorbing ceiling panel and / or soundabsorbing wall panel in such a way, that the surface 0b of the first layer 10 is facing the ceiling or wall and the surface 0a of the second layer 1 is facing the room. The average length and average width of the second fragments 2a are chosen to provide a smooth and fine surface finish, while the average length of the first fragments 20a is chosen independently to ensure that the acoustic building panel 0 is stable and lightweight.

[0042] Fig. 4 - Fig. 6 are described together in the following. Fig. 4 shows a detailed schematic cross sectional view into section B (c.f. Fig. 3) of the second layer 1 of the acoustic building panel 0. Fig. 5 is a detailed schematic cross sectional view through a second fragment 2a coated with solidified second binding agent 3. Fig. 6 shows a detailed schematic cross sectional view into section C (c.f. Fig. 3) of the first layer 10.

[0043] The second support material 2 comprises second fragments 2a made from wood chips having an average length of 1 mm and an average width of 0.5 mm, whereby the average length of the second fragments 2a is measured as the average of the largest diameters of circles around the second fragments 2a and the average width of the second fragments 2a is measured as the average of the smallest diameters of circles around the second fragments 2a. The second fragments 2a are bonded together by the solidified second binding agent 3 that comprises caustic magnesite. Open and closed cavities 3a are formed continuously distributed with their cavity centres inside an enveloping section 3b of the solidified second binding agent 3, wherein said enveloping section 3b is enveloping the second fragment 2a and is in direct contact with the second fragment 2a. The void spaces 9 between the second fragments 2a are structurally different from the cavities 3a formed inside the enveloping section 3b of the solidified second binding agent 3. The first fragments 20a are bonded together by the solidified first binding agent 30 that also comprises caustic magnesite.

Claims

Claims1. Acoustic building panel (0) for installation as sound-absorbing ceiling panel and / or sound-absorbing wall panel, wherein said acoustic building panel (0) is provided by a method comprising the steps:A1) providing a first support material (20) and a first binding agent (30);A2) providing a first mixture (50) by mixing said first support material (20) and said first binding agent (30);A3) forming a first layer (10) from said first mixture (50);B1) providing a second support material (2), a second binding agent (3), and an airentraining agent (4);B2) providing a second mixture (5) by mixing said second support material (2), said second binding agent (3), and said air-entraining agent (4);B3) forming a second layer (1) from said second mixture (5) arranged on said first layer (10); andC) solidifying said first binding agent (30) and said second binding agent (3).

2. Acoustic building panel (0) according to claim 1 , wherein said first support material (20) is composed of first fragments (20a) having a length in a range between 1 cm and 35 cm, preferably between 3 cm and 30 cm, more preferably between 5 cm and 25 cm, and wherein said first fragments (20a) have a thickness of at least 1 mm, preferably of at least 2 mm, more preferably of at least 3 mm, and / or wherein said second support material (2) is composed of second fragments (2a) having a length in a range between 0.2 mm and 4 mm, preferably between 0.3 mm and 3 mm, more preferably between 0.4 mm and 2 mm.

3. Acoustic building panel (0) according to claim 2, wherein said first fragments (20a) and said second fragments (2a) comprise synthetic and / or organic chips, and / or said first fragments (20a) and said second fragments (2a) comprise synthetic and / or organic fibres, preferably wherein said first fragments (20a) and said second fragments (2a) comprise wood chips and / or wood fibres.

4. Acoustic building panel (0) according to anyone of the claims 2 or 3, wherein said second fragments (2a) have a width in a range between 0.5 to 1.0 times the length of said second fragments (2a), preferably between 0.7 to 1.0 times the length of said second fragments (2a), more preferably between 0.9 to 1.0 times the length of said second fragments (2a).

5. Acoustic building panel (0) according to anyone of the preceding claims, wherein said second layer (1) has a thickness of at least 3 mm, preferably at least 5 mm, more preferably at least 10 mm, and / or wherein said first layer (10) has a thickness of at least 10 mm, preferably at least 20 mm, more preferably at least 30 mm.

6. Acoustic building panel (0) according to anyone of the preceding claims, wherein said second binding agent (3) is provided with at least 50 wt.%, preferably with at least 60 wt.%, more preferably with at least 70 wt.% of the total amount of said second mixture (5).

7. Acoustic building panel (0) according to anyone of the preceding claims, wherein said air-entraining agent (4) is provided in an amount in a range between 0.1 wt.% and 2.0 wt.%, preferably between 0.1 wt.% and 1.5 wt.%, more preferably between 0.2 wt.% and 1.0 wt.%, of the amount of said second binding agent (3).

8. Acoustic building panel (0) according to claim 7, wherein the amount by wt.% of said air-entraining agent (4) is chosen such that the airflow resistivity of the acoustic building panel (0) is smaller than 160000 Pa*s / m2, preferably smaller than 120000 Pa*s / m2, more preferably smaller than 80000 Pa*s / m2.

9. Acoustic building panel (0) according to anyone of the claims 7 or 8, wherein the solidified second binding agent (3) comprises enveloping sections (3b) that are in direct contact with said second fragments (2a), and wherein the amount by wt.% of said airentraining agent (4) is chosen such that open and / or closed cavities (3a) are formed continuously distributed inside said enveloping section (3b) of the solidified second binding agent (3).

10. Acoustic building panel (0) according to claim 9, wherein said cavities (3a) have a size, shape and distribution to be formed permeably interconnected within said solidified second binding agent (3) or to be formed separated within said solidified second binding agent (3).

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