The present application is a U.S. National Stage application under 35 USC 371 of PCT Application Serial No. PCT/EP2016/071378, filed on 9 Sep. 2016; which claims priority from EP Patent Application No. 15020158.0, filed 11 Sep. 2015, the entirety of both of which are incorporated herein by reference.
The invention relates to acoustic panels, grids for acoustic panels, suspended ceiling systems and a method for producing an acoustic panel, especially a man-made vitreous fibre (MMVF) panel, having a first major face and an opposite second major face, with the first major face comprising a facing with a surface coating.
Acoustic correction is an important part of creating good indoor environments, and this is of increasing concern, e.g. in open plan offices, schools and hospitals. Noise is a disturbing factor, which may have a negative influence on health and productivity. Acoustic panels can be used to achieve high level of acoustical comfort.
However in some cases acoustic panels are left out of consideration because the present panels have a surface, which is less than optimum in terms of light reflection.
US2007/0277948 A1 discloses an acoustical tile that includes a core and a surface treatment.
US3908059 discloses a ceiling tile that has a decorative face produced by applying a binder and a vast plurality of minute expandable plastic particles to patterned areas of the tile face and then applying heat to expand the particles and/or dry the binder.
According to a first aspect of the present invention it is an object to provide an acoustic panel with a high light reflection and still having acoustic performance.
This object is achieved by the surface coating comprising microspheres.
The microspheres may be made of silica, ceramics or glass. Choice of material for the microspheres may be influenced by cost, demand for strength or processing equipment.
The diameter of the microspheres may be chosen to fit the purpose, depending on the demands on e.g. acoustics, ease of cleaning, cost, whiteness, processing equipment etc. As an example the average diameter may be in the interval 10-200 μm, for example 10-120 μm, such as 15-70 μm. Generally a lower average diameter may give a more smooth texture, whereas a higher average diameter may reduce gloss. Microspheres with a relatively high average diameter may be more fragile and put constraints on the process equipment.
The microspheres provide high light reflection. The effect is comparable with a “bath foam effect”; although the bubbles are colourless, the surface curvature assures a white appearance. In some embodiments the effect may be further enhanced by adding pigment to the microspheres. Alternatively or supplementary the microspheres may have a surface coating or surface treatment.
A further advantage is that the microspheres hide the structure of the surface. Often front facings are directional in that e.g. fibres of the facing are predominantly directed in one direction, and this can often be seen in prior art panels. This means that the installer installing the panels must be careful to align all panels making up e.g. a suspended ceiling in the same direction. This is time consuming, and hence adds to the cost of the final ceiling. If adjacent panels are not aligned to have the same direction, it may have a negative effect on the aesthetics of the room.
Furthermore the microspheres are found to make the surface coating of the surface more robust, thereby making the surface coating more easy to clean.
According to an embodiment, the facing is a non-woven or a felt having an air permeability of 400-900 I/m2/s. Air permeability in this range is found to provide a good compromise between a closed surface with optimum visual quality in terms of smoothness, light reflection etc and an open surface to provide acoustic performance, in particular sound absorption. The facing may be based on glass fibres, which have a favourable reaction to fire, whereas in other cases the facing may be based on for example plastic fibres to provide a softer facing, or a combination of plastic fibres and glass fibres. The facing may include a pigment or dye to provide the colour wanted, e.g. to provide a white facing with an L-value of at least 95.
An aspect of the invention relates to a suspended ceiling grid comprising a surface coating on surfaces visible in the installed state of the suspended ceiling. The surface coating comprises microspheres, which have the effect that the light reflection of the grid surfaces is comparable with the light reflection of the panels. Further it is found that the microspheres make the coated surface more robust and thus easier to clean.
A further aspect of the invention relates to a suspended ceiling system comprising an acoustic panel as defined above and a grid as outlined above.
Another aspect of the invention relates to a method for producing an acoustic panel comprising the steps of providing an acoustic panel, especially a MMVF panel, attaching a front facing to a first major face of the panel, applying a surface coating on the front facing, the surface coating comprises microspheres, and that prior to applying the surface coating, the surface coating is conditioned to have a viscosity of 20-40 s DIN CUP4.
This specific viscosity range is found to provide a suitable compromise of ease of application of the surface coating, good coverage of the surface, while providing a coating, which will not be too detrimental on the acoustic properties of the panels, especially with regard to sound absorption. In some cases a more narrow range of 28-38 s DIN CUP4 may be appropriate.
The microspheres are typically balls of ceramics, glass or silica with vacuum or air filled, and hence the microspheres are relatively light (generally e.g. 0.2 kg/dm3). Due to the light weight of such microspheres, there is a tendency that the microspheres will migrate to the top of a tank containing the coating. Hence the surface coating is conditioned e.g. by mixing or stirring to have a homogeneous viscosity in tank, e.g. with a maximum variation in viscosity of 10% in the coating.
According to an embodiment the surface coating is applied using a low viscosity coating technique, such as using rollers, brushes, spray nozzles or curtain coating.
The invention will be described in the following by way of example with reference to the drawings in which:
In the sketch of
Microspheres (3) of the coating can be seen in the close-up photo of
In the sketch of
A test to determine wet-scrub resistance of coated ceiling panels was carried out. Test samples were 430×110×6 mm panels of MMVF with a facing and coating including microspheres. The test was performed on an Erichsen scrub resistance tester in compliance with PN-EN ISO 11998:2007 requirements, however a soft PU sponge and not a brush, was used as a scrub body. The appearance of the coatings was assessed after 100, 200 and 500 cycles. Rating scale 1-5 was used to describe test results (1=Best, 5=Worst):
As can be seen in the table below the sample showed excellent scrub resistance.
A sample measuring 1200×600×20 mm was tested for sound absorption according to BS EN ISO 354:2003 with very favourable results. Sound absorption coefficient of αw=1.00 was reached (Class A), calculated to EN ISO 11654:1997 and NRC 0.95 calculated to ASTM C 423-01.
Measurement of light reflection of a sample of a panel provided with a coating with microspheres was performed. Spectral reflection was measured using a Perkin-Elmer Lambda 900 spectrophotometer equipped with an integrating sphere, geometry 8°/d. Reflection values, including and excluding specular components, was measured in steps of 5 nm from 380 up to and including 780 nm. From the results the X, Y, Z, x, y and L*, a* and b* coordinates were derived for a light source D65 and an observer of 10° (ISO 7724).
Additionally diffusivity measurements were executed with calibration in “including specular component” modus, while the actual measurement were executed in the “excluding specular components” modus. By doing so the amount of diffuse reflected light compared to the total amount of reflected light is measured.
Gloss was measured using a BYK-trigloss multiangle gloss measuring device. This device projects a light beam onto the sample's surface and measures the intensity of the specular reflected light. The angle can be chosen 20°, 60° or 85°. The intensity of the reflected light beam is expressed in gloss units.
Diffusivity is very high, and the very high diffusivity is confirmed by the results of the gloss measurements, which show extremely low values.
With the high light reflection and low gloss the panels provide more light in a room equipped with the panels, and thereby the cost of lighting may be reduced, and further the living conditions are improved with a positive influence on the mood and productivity of people in the room.
Number | Date | Country | Kind |
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15020158 | Sep 2015 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2016/071378 | 9/9/2016 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2017/042372 | 3/16/2017 | WO | A |
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Number | Date | Country | |
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20180251976 A1 | Sep 2018 | US |