EP1180186B2 - Flexible polymer material sheet for stretched constructions and false ceiling comprising this sheet - Google Patents

Abstract

A flexible sheet material of thickness less than half a millimeter for making tensioned structures such as false ceilings, in particular, the material including microprojections formed by displacing the material from which it is made, said material presenting an acoustic absorption coefficient which is higher than that of the same material without said projections.

Description

The invention relates to the technical field of relatively thin sheet materials, typically less than half a millimeter, used for the realization of ceilings, false ceilings, false walls, wall coverings, by powering these materials in sheet.

In the prior art, a large number of embodiments of such materials, as well as their use in suspended ceilings, are already known.

By way of example, reference can be made to the French patent applications published under the following numbers: 2 767 851, 2 751 682, 2 734 296, 2 712 006, 2 707 708, 2 703 711, 2 699 211 , 2,699,209, 2,695,670, 2,691,193, 2,685,036, 2,645,135, 2,630,476, 2,627,207, 2,624,167, 2,623,540, 2,619,531, 2,597,906, 2,611,779, 2, 592,416, 2,587,447, 2,561,690, 2,587,392, 2,552,473, 2,537,112, 2,531,012, 2,524,922, 2,475,093, 2,486,127, 2,523,622, 2,310,450.2, 270,407. , 2 202 997, 2 175 854, 2 145 147, 2 106 407, 2 002 261, 1 475 446, 1 303 930, 1 287 077. Reference may also be made, by way of example, to the following documents: US-A-5,058,340 , US-A-4,083,157 , EP-A-643,180 , EP-A-652,339 , EP-A-588 748 , EP-A-504,530 , EP-A-338 925 , EP-A-281,468 , EP-A-215,715 , EP-A-089 905 , EP-A-043 466 , WO-A-94/12741 , WO-A-92/18722 . Reference may also be made to the following French patent applications issued by the Applicant: 2,736,615, 2,756,600, 2,727,711, 2,712,325, 2,699,613, 2,695,670, 2,692,302 and 2,658,849.

The materials known in the prior art for the production of false ceilings or tight false walls are most often polymeric materials provided with many qualities such as: fire resistance, airtightness as well as dust or humidity, ease of maintenance.

False ceilings obtained using such materials may incorporate thermal insulators, spotlights or various lighting, as well as ventilation or ventilation openings or sprinklers. Removable, they allow, if necessary, an intervention in the plenum.

The polymeric materials for stretch ceilings known in the prior art, translucent or opaque, dyed or not in the mass, matt, lacquered, marbled, suede or satin, can thus be used both in industrial and hospital environments, for community amenities, laboratories or homes.

The lacquered finish allows a mirror effect often used in shopping centers, a matte finish rather close to a plaster aspect being more usual to traditional decorations.

Despite their numerous advantages that have led to their increasing use in various environments, the false ceilings and false walls in tensioned polymer fabric of the prior art have the major disadvantage of presenting poor acoustic properties, the reverberation of sounds on such ceilings. tense being particularly high.

The attenuation of sound reverberation on walls and ceilings is a technical problem that has been known for a long time.

Several technical solutions could be envisaged.

According to a first technique, soundproofing panels comprise a perforated plate made of metal or plastic fixed on a mineral wool type support or polyurethane foam. For this first technique of passive sound absorption by fibrous or porous materials, reference may be made, for example, to the following documents: EP-A-013 513 , EP-A-023 618 , EP-A-246 464 , EP-A-524,566 , EP-A-605,784 , EP-A-652 331 , FR-A-2 405 818 , FR-A-2,536,444 , FR-A-2,544,358 , FR-A-2,549,112 , FR-A-2,611,776 , FR-A-2,611,777 , FR-A-2,732,381 , US-A-4,441,580 , US-A-3,948,347 . This technique leads to an assembly in which the phonetically absorbing counter-parison is integral with an apparent perforated facing. The perforations are intended to allow attenuation of the waves by the acoustic absorbent material, the latter can not be left visible because too fragile, sometimes messy surface and unsightly gross appearance.

According to a second technique, the panels forming the walls such as for example suspended ceilings are provided with cavities whose volume is calculated to tune them on certain frequency ranges, these cavities being protected by a porous facing. For this second type of technique, using Helmholtz resonators, reference may be made, for example, to the documents DE-PS-36 43 481 , FR-A-2,463,235 .

According to a third technique, used in the field of suspended ceilings, the apparent surface of the ceiling panels is embossed or provided with grooves or deep cavities. For example, we can refer to documents FR-A-2,381,142 , FR-A-2,523,621 , FR-A-2,573,798 , WO-A-80 / 01,183 , WO-A-94/24382 .

According to a fourth technique, honeycomb webs form absorbent membranes. This technique, expensive, is sometimes used in recording studios.

The document US 3,782,495 describes acoustical suspended suspended ceiling tiles comprising a perforated sheet metal or plastic sheet, sheet adhered to a frame beneath a block of sound insulating glass wool, the plastic sheet being heat-treated, coated, printed, hue or color to obtain a decorative effect.

The document EP 0 816 583 discloses a device for reducing acoustic levels in buildings, comprising acoustic attenuation elements formed of several leaves located at a distance from each other and parallel to each other, suspended vertically, these sheets being made of rigid polymer material such as polycarbonate or polyethylene, these sheets can be wound on a storage cylinder.

The document EP 0 399 935 describes an air distribution device for heating, ventilation or air-conditioning purposes, the walls of the air distribution network being constituted by false ceilings made of fabric stretched at least partly permeable to the air for a loss load of about 1Pa for a nominal flow rate of 10 m ³ per hour per m ² of permeable surface.

The document DE 197 54 107C discloses acoustic panels of polyester or metal such as steel or aluminum, placed parallel to each other in suspension.

None of the technical solutions known in the prior art for improving the sound properties of walls or suspended ceilings is adapted to the particular technique of ceilings or walls stretched.

A first object of the invention is to provide a flexible polymeric material, in sheet, suitable for use in tension structures for decoration, masking or display, such as in particular false ceilings, false walls, this material having acoustic properties greatly improved.

A second object of the invention is to provide a material as above, the visual appearance of which remains perfectly adapted to its use, both in industrial and hospital environments, as well as for public facilities or modern living quarters. or historical.

For these purposes, the invention relates, in a first aspect, to a flexible sheet material (1) having a thickness (e1) of less than half a millimeter, for the production of tensile structures such as, in particular, false ceilings, characterized in that it comprises micro-reliefs extending over a height (h) of a few microns to 100 microns, micro-reliefs (2) formed by embossing the constituent material of the material (1) which thus presents a higher sound absorption coefficient than the same material without said reliefs, the microreliefs being obtained by a needling step, locally pushing the constituent material of the sheet, in a predetermined pattern, to its micro-perforation, the step needling being conducted while the sheet of material is placed under a voltage of the order of that of its final use in a tensile structure.

• la hauteur des micro-reliefs, mesurée suivant une direction perpendiculaire au plan de ladite feuille au droit de ces micro-reliefs est inférieure à trois fois l'épaisseur de ladite feuille ;
• ses micro-reliefs forment des saillies sur une seule face de ladite feuille ;
• chacun de ses micro-reliefs est disposé suivant tes noeuds d'un motif régulier ;
• tous ses micro-reliefs sont disposés suivant les noeuds d'un seul motif, par exemple à maille carrée ;
• le matériau est pourvu de micro perforations, d'ouverture inférieure à quatre dixièmes de millimètre ;
• les micro perforations sont disposées suivant les noeuds d'un motif ;
• le matériau est choisi parmi le groupe comprenant les chlorures de polyvinyle plastifiés, chlorure de vinylidène et copolymères chlorure de vinyle / chlorure de vinylidène ;
• la surface occupée par les micro-reliefs est comprise entre 0,5% et 10% de la surface de ladite feuille ;
• la densité de micro-perforations est comprise entre 2 et 60 par centimètre carré, de préférence 15 à 35 par centimètre carré, et plus particulièrement entre 20 et 30 par centimètre carré.

According to various embodiments, this material also has the following characters, possibly combined:

• the height of the micro-reliefs, measured in a direction perpendicular to the plane of said sheet at the right of these micro-reliefs is less than three times the thickness of said sheet;
• its micro-reliefs project on one side of said sheet;
• each of its micro-reliefs is arranged according to your knots of a regular pattern;
• all its micro-reliefs are arranged according to the nodes of a single pattern, for example square mesh;
• the material is provided with micro perforations, opening less than four tenths of a millimeter;
• the micro-perforations are arranged according to the nodes of a pattern;
• the material is selected from the group consisting of plasticized polyvinyl chlorides, vinylidene chloride and vinyl chloride / vinylidene chloride copolymers;
• the surface occupied by the micro-reliefs is between 0.5% and 10% of the surface of said sheet;
• the micro-perforation density is between 2 and 60 per square centimeter, preferably 15 to 35 per square centimeter, and more particularly between 20 and 30 per square centimeter.

The method of producing a sheet of material as presented above, comprises a needling step, locally pushing the constituent material of the sheet to its micro perforation, in a predetermined pattern. The needling step is performed without the sheet undergoes a removal of material. The needles used in the needling process have an extreme diameter less than one tenth of a millimeter, for example of the order of four hundredths of a millimeter. The needling step is conducted while the sheet of material is placed under a voltage of the order of that of its end use in a tensile structure.

According to a second aspect, the invention relates to a false ceiling, characterized in that it comprises a sheet of a material as presented above, energized with respect to support means.

• les figures 1a, 1b et 1c illustrent différents modes de réalisations d'un matériau pour toile tendue selon l'invention ;
• la figure 2 est un graphe représentant les valeurs de coefficient d'absorption acoustique mesurées, en fonction de la fréquence moyenne tiers d'octave dans quatre conditions expérimentales 1b,2b,3 et 4, ainsi que pour un échantillon de référence étalon ;
• la figure 3 est un graphe analogue à celui de la figure 2, pour les conditions expérimentales 5, 6 et 7 ;
• la figure 4 est un graphe analogue à celui de la figure 3, pour les conditions expérimentales 8, 8b, 9, les résultats obtenus pour les conditions 1b, 2b étant reportées sur le graphe de cette figure 4 afin de comparaison ;
• la figure 5 est un graphe analogue à celui de la figure 2, pour la condition expérimentale 10, les résultats obtenus pour les essais 3, 6 étant reportés sur ce graphe de la figure 5, afin de comparaison ;
• la figure 6 est un graphe analogue à celui de la figure 2, pour la condition expérimentale 11, les résultats obtenus pour les conditions 4 et 5 étant reportés sur ce graphe de la figure 6, afin de comparaison ;
• la figure 7 est un graphe analogue à celui de la figure 2, pour les conditions expérimentales 12, 13 et 14 ;
• la figure 8 est un histogramme des valeurs de coefficient d'absorption sonore en fonction de la valeur de fréquence tiers d'octave, pour les conditions expérimentales A ;
• la figure 9 est un histogramme analogue à celui de la figure 8, pour les conditions expérimentales B ;
• la figure 10 est un histogramme analogue à celui de la figure 8, pour les conditions expérimentales C.

Other objects and advantages of the invention will become apparent from the following description of embodiments, which description will be made with reference to the accompanying drawings in which:

• the Figures 1a, 1b and 1c illustrate different embodiments of a stretched canvas material according to the invention;
• the figure 2 is a graph representing the measured sound absorption coefficient values, as a function of the average third octave frequency in four experimental conditions 1b, 2b, 3 and 4, as well as for a reference standard sample;
• FIG. 3 is a graph similar to that of FIG. figure 2 for experimental conditions 5, 6 and 7;
• the figure 4 is a graph similar to that of FIG. 3, for the experimental conditions 8, 8b, 9, the results obtained for the conditions 1b, 2b being plotted on the graph of this figure 4 for comparison;
• the figure 5 is a graph similar to that of the figure 2 for the experimental condition 10, the results obtained for the tests 3, 6 being plotted on this graph of the figure 5 , for comparison;
• the figure 6 is a graph similar to that of the figure 2 , for the experimental condition 11, the results obtained for the conditions 4 and 5 being plotted on this graph of the figure 6 , for comparison;
• the figure 7 is a graph similar to that of the figure 2 for experimental conditions 12, 13 and 14;
• the figure 8 is a histogram of the sound absorption coefficient values as a function of the third octave frequency value, for the experimental conditions A;
• the figure 9 is a histogram similar to that of the figure 8 for experimental conditions B;
• the figure 10 is a histogram similar to that of the figure 8 , for experimental conditions C.

We first refer to the figure 1 .

The figure 1a is a front view of a material 1 thickness of the order of one tenth of a millimeter, provided with substantially identical micro-reliefs 2 regularly distributed over a square mesh network. On the figure 1b is shown in greatly enlarged view the shape of these reliefs 2, when seen in section perpendicular to the plane of the figure 1 . The dimensions of the micro reliefs are such that they appear almost punctual on the figure 1 . These reliefs 2 are, in the embodiment considered here, in the form of cups substantially of revolution shape about an axis 3 perpendicular to the mean plane of the sheet of material 1 laid flat. These reliefs extend over a small height h, of the order of a few microns to a few tens of microns, and have an apparent opening of the order of two tenths of a millimeter.

In the embodiment shown, these micro reliefs are provided with a perforated bottom wall 4. These through holes 19 are derived from a needling needles whose tips have a diameter of the order of a few hundredths of a millimeter, for example 4 hundredths of a millimeter.

This needling is performed while the sheet of material 1 is placed under tension. This voltage is of the order of that experienced by the sheet at its place of use, for example in a suspended false ceiling.

The through holes 19, of diameter of the order of a few hundredths of a millimeter, are obtained without removal of material.

The bottom wall 4 of the micro-perforated reliefs 2 is connected to the edge of the cuvettes by an annular wall 5 of revolution about the axis 3. Where appropriate, this wall 5 may have a thickness e5 less than that e1 measured between the reliefs for the sheet of material 1. This difference in thickness will be all the more marked as the height h of the micro-reliefs 2 is large, thickness e1 given.

• pas p entre les micro-reliefs : 1 mm ;
• densité de micro-reliefs, par centimètre carré : 25 ;
• hauteur des reliefs : de quelques microns à 100 microns.

By way of example, the following values can be implemented:

• not p between micro-reliefs: 1 mm;
• density of micro-reliefs, per square centimeter: 25;
• height of the reliefs: from a few microns to 100 microns.

Other embodiments may be envisaged.

According to a first type of embodiment variant, the reliefs are not all identical, two or more populations of reliefs that can be distinguished, these reliefs being of different shapes.

According to a second type of embodiment variant, possibly combined with the first type above, the reliefs are not all substantially punctual, but extend in at least one direction to form micro grooves and micro grooves.

According to a third type of variant, possibly combined with one or both of the above types, all the reliefs are not symmetrical of revolution with respect to an axis substantially perpendicular to the mean plane of the sheet of material 1.

Thus, for example, the bowl bottoms, when viewed in plan, may be square, rectangular, oval, regular polygon-shaped or not. The mesh of the network of micro-reliefs is square, in the embodiment of the figure 1 . In other embodiments, this mesh is not square but rectangular.

In some embodiments, at least two different micro-relief, mesh and / or p1, p2, p'2 arrays are arranged on the sheet of material 1, as shown in FIG. figure 1c .

Depending on the density of micro-reliefs, the pattern of their distribution, their height, the inventors found that the visual impact of the placement of these reliefs is more or less marked, as well as the impact on the acoustic properties of the sheet of material 1, a dramatic improvement of the acoustic properties that can be achieved however without significant visual impact, the realization of micro-reliefs micro perforated proving particularly at once effective in terms of acoustics and almost undetectable to the look. While keeping a conventional aspect of stretched canvas, thus clearly out of perforated suspended ceilings or mesh, the invention allows in particular to achieve acoustic properties similar to those of suspended ceilings noise.

When a sheet of material provided with micro-perforations is seen according to the arrow F of the figure 1b micro-perforations 19 do not substantially alter its visual appearance. The inventors have notably found that the production of micro perforations 19 as represented in FIG. figure 1b is almost undetectable when combined with a matte finish for the visible face 20 of the sheet of material 1. The improved acoustic properties for the material can avoid the introduction of fibrous insulation, which can generate dust and microfibers whose impact on health could be discussed.

The improvement of the acoustic properties of the sheets of material, by placing micro-perforated micro-reliefs will now be illustrated with the aid of some experimental results. Before presenting these results, the following elements of acoustics must be recalled, insofar as these elements are not within the domain of those skilled in the art of ceilings and walls in stretched cloths.

The sound waves are derived from the propagation of pressure variations in the elastic media, by wave fronts, at a rate depending in the solids, of the modulus of elasticity and the density of the solid (of the order of 500 m / s in a cork and 3100 m / s in a common concrete for example). The spectrum audible by the human ear is formed by the frequencies of the vibrations of the sounds between 16 Hertz and 20 000 Hertz, when these sounds are emitted beyond a certain acoustic pressure (threshold of audibility equal to four phones). The frequency domain of the speech is between 10 and 10 kHz approximately, understandable speech being focused on frequencies between 300 Hz and 3 kHz. The domain of musical frequencies is between about 16Hz and 16kHz, an octave corresponding to a doubling of frequency. Instrument or voice Low frequency (Hz) High frequency (Hz) Violin 200 3000 Piano 30 4000 Flute 250 2500 Cello 70 800 Bass 40 300 Tuba 50 400 Trumpet 200 1000 Organ 16 1600 Low 100 350 Baritone 150 400 Tenor 150 500 Alto 200 800 Soprano 250 1200

• les matériaux poreux rigides, tels que bétons poreux et mousses rigides, dans lesquels les réseaux de capillaires forment résistance acoustiques ;
• les matériaux poreux élastiques tels que laines minérales, feutres, polystyrènes, dans lesquels l'énergie acoustique est dissipée par friction solide ;
• les matériaux à résonance acoustique, agissant selon le principe des résonateurs d'Helmholtz, tels que panneaux perforés ;
• les matériaux à résonance mécanique, fonctionnant sur la base de l'oscillateur amorti.

The sound absorption can be obtained by converting acoustic energy into deformation work or internal friction in a porous absorbent material of low acoustic impedance, or by means of dissipating resonator, in the form of heat by internal friction, the acoustic energy of the sounds of frequencies close to the eigenfrequencies of the resonator. In a conventional manner, there are four types of phonic insulators:

• rigid porous materials, such as porous concretes and rigid foams, in which the capillary networks form acoustic resistance;
• elastic porous materials such as mineral wools, felts, polystyrenes, in which acoustic energy is dissipated by solid friction;
• acoustic resonance materials, acting on the principle of Helmholtz resonators, such as perforated panels;
• mechanical resonance materials, operating on the basis of the damped oscillator.

An absorption index of sounds α (without units) is defined, this index α being the normalized difference of the incident and reflected acoustic energy. This index depends on the frequency of the incident sounds. As the sound attenuation in air is a function of temperature, pressure and relative humidity, the measurements of the absorption index must be carried out at known temperature, pressure and humidity (see French standard NF S 30,009). With regard to the measurement standards of this index, reference may be made, for example, to the following documents: international standard ISO 354, French standard NF EN 20354, NF S 31 065, standard ASTM C423 of the United States of America. The table below gives some values of this sound absorption index α. α
for 125 Hz α
for 500 Hz α
for 2000 Hz Rough on masonry 0.02 0.02 0.03 Crimped with lime 0.03 0.03 0.04 Lightweight concrete 0.07 0.22 0.10 Mortar 0.03 0.03 0.07 Acoustic plate thickness 2.5 cm with 3 cm of air 0.25 0.23 0.74 drawn on a wall 0.15 0.23 0.73 Insulating panels thickness 2 cm applied on a wall 0.13 0.19 0.24 with 3 cm of air 0.15 0.23 0.23 with 3 cm of glass wool 0.33 0.44 0.37 wood door 0.14 0.06 0.10 parquet 0.05 0.06 0.10 plywood 3mm air 2cm 0.07 0.22 0.10 plywood 3 mm on a wall 0.07 0.05 0.10

Similarly, a reflection index of the sounds p, a sound dissipation index δ and a sound transmission index are defined.

At the interface between two environments, the principle of conservation of acoustic energy implies that: ρ + τ + δ = 1, ρ + α = 1.

The greater the acoustic energy dissipated by an acoustic insulation, the lower the reflected acoustic energy will be, reducing the echo effect.

The echo or reverberation due to the reflection of sounds on an obstacle generates interference that can greatly increase the sound level in a room and make conversations difficult to follow.

où V est le volume de !'espace libre ; A est la surface absorbante ; α est l'indice d'absorption défini ci dessus.For this reverb, we define a reverberation time T, according to Sabine's formula $$\mathrm{T}\mathrm{=}\mathrm{0163}\mathrm{V}\mathrm{/}\mathrm{\alpha A}$$

where V is the volume of the free space; A is the absorbent surface; α is the absorption index defined above.

This formula of Sabine is established from the assumption of a perfectly homogeneous distribution of the reverberated field. The reverberation time is the time at which the acoustic energy has decreased by 60 dB, ie 1 ppm from its initial value.

These notions of acoustics having been recalled, will be presented below some experimental results obtained under standardized conditions.

In a first series of tests, twelve strips of material were subjected to sound absorption tests.

The sheets of material, of dimensions 9'x8 'were fixed on the surface of a parallelepiped box of glass wool, wall thickness 3/4', dimensions 9'x8'x4 ', the box being placed on a corrugated steel plate.

The glass wool box was removed from the reverberation chamber for measurements in an empty chamber. The results of the tests are given in Table I below.

The frequencies mentioned in Table I are the center frequencies of the normalized third octave bands. Table I- First series of tests Frequencies (Hz) Test 1b Test 2b Test 3 Test 4 Test 5 Test 6 Test 7 Test 8 Test 9 Test 10 Test 11 Test 8b 125 0.43 0.71 0.77 0.77 0.37 0.43 0.47 0.80 0.46 0.33 0.42 0.90 160 0.31 0.70 0.68 0.60 0.43 0.45 0.49 0.97 0.59 0.61 0.59 1.01 200 0.18 0.69 0.69 0.66 0.41 0.41 0.40 0.89 0.42 0.49 0.55 0.93 250 0.21 0.63 0.73 0.72 0.49 0.51 0.43 0.88 0.51 0.63 0.61 0.97 315 0.29 0.79 0.87 0.88 0.68 0.73 0.65 0.90 0.70 0.79 0.75 0.94 400 0.39 0.87 1.00 1.03 0.81 0.83 0.70 0.82 0.76 0.83 0.83 0.76 500 0.41 0.82 1.02 1.03 0.82 0.85 0.70 0.75 0.74 0.92 0.93 0.69 630 0.39 0.73 0.98 0.99 0.87 0.87 0.68 0.69 0.69 0.91 0.90 0.65 800 0.37 0.69 1.00 1.00 0.93 0.93 0.67 0.68 0.68 0.94 0.93 0.67 1000 0.34 0.61 1.01 1.00 0.97 0.99 0.61 0.63 0.60 0.95 0.93 0.67 1250 0.35 0.58 1.06 1.06 1.02 1.04 0.59 0.61 0.57 1.01 1.00 0.62 1600 0.37 0.56 1.09 1.09 1.05 1.07 0.54 0.57 0.53 1.02 1.00 0.59 2000 0.35 0.48 1.08 1.04 1.07 1.07 0.50 0.50 0.44 0.97 0.97 0.52 2500 0.34 0.43 1.07 1.01 1.07 1.07 0.44 0.43 0.34 0.91 0.88 0.49 3150 0.30 0.36 1.01 0.91 1.01 1.01 0.38 0.36 0.24 0.76 0.70 0.45 4000 0.27 0.32 0.93 0.78 0.97 0.98 0.37 0.33 0.10 0.57 0.46 0.43 CAA 0.35 0.65 0.95 0.95 0.85 0.85 0.55 0.70 0.55 0.85 0.85 0.70

The conditions of these tests are presented in Table II. Table II- Experimental conditions for the first series of tests Test number Sheet type support Sona Spray Acoustical Finish coating from K13 Spray-On Systems Fiberglass from Owens Coming on steel plate 1b Smooth Steel plate No No 2b Smooth Steel plate No 6 "R19 3 Perforated NLM41 Steel plate No 6 "R19 4 Perforated NL601 Steel plate No 6 "R19 5 Perforated NL601 Steel plate 1 " No 6 Perforated NLM41 Steel plate 1 " No 7 Smooth Steel plate 1 " No 8 Smooth - No 6 "R19, 3" from the sheet 8b Smooth - No 3-7 / 8 "RA24 (1.5 #) to 5.75" from the sheet 9 Smooth Steel plate 2.25 " No 10 Perforated NLM41 Steel plate 2.25 " No 11 Perforated NL601 Steel plate 2.25 " No

The so-called "perforated NLM41" sheets are of the type sold by the applicant under the reference NewLine NLM41. These sheets are provided with large perforations (circular holes of diameter four millimeters), obtained by removal of material, the hole density being less than one per square centimeter. These circular holes are intended to allow ventilation of the plenum and possible smoke extraction: this range of products NLM41 is classified M1 / B1 / Fire 1.

The sheets called "perforated NL601" are of the type sold by the applicant under the reference NewLine NL601. These sheets are also provided with large perforations (circular holes of diameter one millimeter), perforations obtained by removal of material. These circular holes are intended, like those of NLM41 sheets, to allow ventilation of the plenum and possible smoke extraction, this range of products NL601 being classified M1 / B1 / Fire 1.

• la figure 2 donne les résultats pour les essais 1b, 2b, 3, 4, par rapport à cinq valeurs obtenues pour un étalon de référence ;
• la figure 3 donne les résultats pour les essais 5, 6, 7, par rapport audit étalon de référence ;
• la figure 4 est un graphe rassemblant les résultats des essais 8, 8b et 9, comparés à ceux obtenus pour les essais 1b, 2b, et 7 ;
• la figure 5 est un graphe représentant les résultats obtenus pour l'essai 10, comparés à ceux des essais 3 et 6 ;
• la figure 6 est un graphe représentant les résultats obtenus pour l'essai 11, comparés à ceux obtenus pour les essais 4 et 5.

The curves corresponding to these results are given in Figures 2 to 7 :

• the figure 2 gives the results for tests 1b, 2b, 3, 4, compared to five values obtained for a reference standard;
• Figure 3 gives the results for tests 5, 6, 7, with respect to said reference standard;
• the figure 4 is a graph summarizing the results of tests 8, 8b and 9, compared to those obtained for tests 1b, 2b, and 7;
• the figure 5 is a graph representing the results obtained for test 10, compared to those of tests 3 and 6;
• the figure 6 is a graph representing the results obtained for test 11, compared to those obtained for tests 4 and 5.

The comparison of the curves 1b and 2b shows the impact of the implementation of a conventional fibrous sound insulation, as it can be done in the plenum.

ce panneau se comportant comme un ensemble de résonateurs d'Helmholtz, sa valeur maximale d'absorption acoustique restant tributaire de la valeur du coefficient d'amortissement et du taux de perforation. Ce type de mécanisme est mis en oeuvre dans les plafonds suspendus perforés.The comparison of the curves 3 and 4 on the one hand with the curves 1b 2b on the other hand shows that the placement of perforations on the stretched sheet makes it possible to increase the sound absorption properties, in particular at the high frequencies, the domain in which the introduction of the fibrous insulation is not very effective. The inventors have sought an explanation for this observation. It turns out that, in the field of acoustics, it is known that a rigid perforated panel of thickness h situated at a distance e from a wall and comprising a number n of cylindrical perforations of radius a, this panel being supported by four orthogonal cleats, has a maximum efficiency pulse of $$\mathrm{\omega }=\mathrm{vs}{\left(\mathrm{n\pi }/{\mathrm{at}}^2\mathrm{e}\left(\mathrm{h}+8\mathrm{at}/3\mathrm{<figure-callout\; id="1"\; label="\pi "\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">\pi </figure-callout>}\right)\right)}^{1/2}$$

this panel behaves as a set of Helmholtz resonators, its maximum sound absorption value remaining dependent on the value of the damping coefficient and the perforation rate. This type of mechanism is implemented in perforated suspended ceilings.

In the case of the stretched fabrics considered here, the sheets of stretched materials are likely to vibrate and are not rigid and dimensionally stable, the thicknesses h are very low compared to sound insulating panels, so that the model presented above can not be used. Other models, known in the field of acoustics, are intended to predict the behavior of perforated diaphragm panels, taking into account the inherent stiffness of the panel and the air compression in the rear part of the panel, as well as its flow through the perforations, which can play a dissipative role.

These very complex models could possibly be invoked with respect to the results obtained during the trials 3,4,5,6,10,11.

Curves 5, 6 and 7 illustrate the impact of placing an acoustic spray coating on the stretched sheets. The effect of this coating is especially marked in high frequencies. Conversely, as shown in figure 4 , for a smooth tensioned sheet, the placement of fibrous insulation (tests 2b, 8, 8b) or the placement of an acoustic spray coating (tests 7 and 9) gives, for frequencies above 400 Hz , results lower than those obtained with perforated sheets with or without spray acoustic coating. In all the cases presented by the tests 1b, 2b, 3,4,5,6,7,8,8b, 9,10 and 11, the acoustic attenuation properties had a large dissymmetry between low and high frequencies.

The inventors have found that, unexpectedly, and without a simple explanation being able to be invoked, the production of micro-reliefs and micro-perforations led to results as favorable as the production of large perforations. The results obtained with micro-perforations are even better in the field of high frequencies, compared to those obtained by large perforations.

Essays 12, 13 and 14 illustrate these amazing results. The conditions of these tests were as follows: temperature = 70F (about 21.2 ° C.), humidity = 64%, atmospheric pressure. A sheet of micro-perforated material of 9'x8 'was tested in an assembly type E 1219. By "micro-perforated" is meant here, with reference to tests 12, 13 and 14, a sheet of PVC material of 17 hundredths of a millimeter of thickness, provided with micro perforations formed by needling, without removal of material, the needles used having an end diameter of the order of 4 hundredths of a millimeter, the density of micro perforations obtained being of the order of three per square centimeter, the perforations being distributed over a mesh as represented in figure 1 at. The sheet was stretched on the upper face of a parallelepiped box unpainted glass fiber wall thickness of 3/4 ", with a volume equal to 10154.72 cu.ft. The results said to" empty chamber "were obtained without placing the box, the sheet of material being placed on a steel plate For these empty chamber tests, the T60 values correspond to the average reverberation times The Acoustic Absorption Coefficient (CAA) and the accuracies The values of NRC and AAC were obtained according to ASTM C423, while for test 12 a 6 "thick layer of polyester wool was obtained in accordance with ASTM C423-90a. The Owens Coming R19 glass was suspended in the box at 3.75 "from the sheet of tensioned material For Test 13, a 1" thick layer of RA24 fiberglass from Owens Corning was suspended in the box at 8.75 "from the sheet of material t For test 14, no material was placed in the box. Table III- Tests N ° 12 13 and 14.
Sound absorption measurements using a reverberation chamber Freq. (Hz) Empty room T60 (s) Incert. % Test 14 T60 (s) Incert. % CAA Prev. Sabins / sq.ft Test 13 T60 (s) Incert% CAA Prec Sabins / Sq.ft Test 12 T60 (s) Incert. % CAA Prev. Sabins / Sq.ft 50 1.63 5 1.31 3.23 0.76 0.26 1.37 2.59 0.52 0.26 1.88 15.29 0.84 0.61 63 1.37 7.56 0.96 4.48 2.15 0.50 0.90 3.25 2.59 0.46 1.01 4.61 1.80 0.50 80 1.60 5.44 1.17 14.97 1.61 0.92 1.12 6.42 1.88 0.48 1.15 4.52 1.71 0.36 100 2.40 5.74 2.21 6.64 0.24 0.32 1.96 9.18 0.64 0.36 1.70 2.44 1.17 0.19 125 3.16 2.37 2.81 3.90 0.27 0.11 2.57 3.86 0.51 0.12 2.37 2.67 0.73 0.09 160 3.56 3.22 3.06 1.99 0.32 0.08 2.63 1.95 0.69 0.08 2.56 4.01 0.76 0.13 200 4.01 2.53 3.55 2.31 0.22 0.06 2.94 2.38 0.63 0.07 2.58 2.07 0.96 0.07 250 5.62 1.34 4.37 2.16 0.35 0.04 3.45 2.53 0.77 0.05 3.18 2.06 0.94 0.05 315 6.67 1.77 5.02 1.43 0.34 0.03 3.81 1.58 0.78 0.03 3.54 1.19 0.91 0.03 400 6.25 0.90 4.53 1.65 0.42 0.03 3.64 1.62 0.80 0.03 3.39 1.77 0.93 0.04 500 7.05 0.62 4.82 1.08 0.45 0.03 3.93 1.28 0.78 0.02 3.85 1.43 0.81 0.03 630 7.23 0.73 4.85 1.29 0.47 0.02 3.99 1.44 0.78 0.03 3.95 1.43 0.79 0.03 800 7.23 0.41 4.65 1.01 0.53 0.02 3.89 0.71 0.82 0.01 3.87 0.84 0.83 0.02 1000 7.17 0.45 4.47 1.06 0.58 0.02 3.85 0.59 0.83 0.01 3.88 0.93 0.82 0.02 1250 6.92 0.45 4.17 0.55 0.66 0.01 3.72 0.51 0.86 0.01 3.70 0.52 0.87 0.01 1600 6.25 0.34 3.83 0.61 0.70 0.01 3.50 0.49 0.87 0.01 3.49 0.61 0.88 0.01 2000 5.29 0.43 3.45 0.73 0.70 0.02 3.21 0.47 0.85 0.01 3.21 0.52 0.85 0.01 2500 4.06 0.49 2.90 0.41 0.68 0.01 2.76 0.42 0.80 0.01 2.76 0.59 0.81 0.02 3150 3.37 0.57 2.54 0.59 0.57 0.02 2.45 0.40 0.78 0.02 2.44 0.48 0.78 0.02 4000 2.80 0.48 2.23 0.46 0.63 0.02 2.17 0.36 0.72 0.02 2.17 0.48 0.72 0.02 5000 2.20 0.55 1.85 0.50 0.59 0.03 1.82 0.40 0.66 0.02 1.80 0.48 0.69 0.03 6300 1.67 0.38 1.48 0.44 0.54 0.03 1.45 0.39 0.62 0.02 1.43 0.44 0.68 0.03 8000 1.21 0.53 1.11 0.50 0.50 0.04 1.09 0.68 0.58 0.05 1.08 0.60 0.65 0.05 10000 0.89 0.78 0.83 0.85 0.51 0.09 0.83 0.61 0.58 0.08 0.82 0.64 0.70 0.08

The values of AAC and NRC obtained are given in Table IV below: Table IV- Tests N ° 12 13 and 14, NRC and AAC values obtained NRC AAC Trial 12 0.85 0.87 Trial 13 0.8 0.8 Trial 14 0.5 0.51

The sound absorption values obtained during tests 12, 13 and 14 are plotted on the graph of the figure 7 , only the frequencies between 125 and 4000 Hz being taken into account, in order to homogeneity of presentation with the graphs of the Figures 2 to 6 .

The combination of a micro-perforated membrane with a fibrous insulation placed at a distance from the rigid wall makes it possible to obtain a homogeneous acoustic attenuation over the entire frequency range considered.

The tests carried out for the first and second series mentioned above involved an acoustic chamber with glass fiber walls, which does not correspond to the actual arrangement of the stretch ceilings.

In order to better evaluate the impact of the presence of the stretched sheet support on the overall acoustic attenuation properties, a third series of tests was carried out under the following conditions.

Test A:

8 'x 9' fiberglass panels with a total weight of 0.25psf, 1 "thick (density 3 Ib / cu.ft) surrounded by a tubular metal frame 4" high and 1- 1/2 "nominal thickness were attached directly to the base wall of the reverberation chamber (ASTM E 795 mounting A).

These frames formed a support for PVC strips of smooth material stretched

Test B:

8 'x 9' panels of smooth PVC (5mil) were placed using a harpoon / rail assembly at 4 "from the bottom wall of the reverberation chamber (ASTM E 795 E90 fitting) .

The support frame for smooth PVC panels is made of metal tubes with a height of 4 "and a nominal thickness of 1-1 / 2".

This frame is fixed externally to the base wall of the reverberation chamber.

A 2 "thick fiberglass board (density 3 Ib / cu.ft) is placed directly on the bottom wall of this chamber.

The total weight of this fiberglass board is 0.49 psf, the PVC band weighing 0.05 psf.

Test C:

8 'x 9' panels of smooth PVC (5mil) were placed using a harpoon / rail assembly at 4 "from the bottom wall of the reverberation chamber (ASTM E 795 E90 fitting) .

The support frame for smooth PVC panels is made of metal tubes with a height of 4 "and a nominal thickness of 1-1 / 2".

This frame is fixed externally to the base wall of the reverberation chamber.

A 1 "thick fiberglass board (density 3 lb / cu.ft) is placed directly on the bottom wall of this chamber.

The total weight of this fiberglass board is 0.25 psf, the PVC band weighing 0.05 psf.

The results obtained are shown in Table V below. Table V- Results obtained for tests AB and C. Sound absorption coefficient Sabins Trial A Sound absorption coefficient Test B Sabins Trial B Sound absorption coefficient Test C Sabins Test C 100 0.05 3.6 0.17 12.5 0.09 6.6 125 0.07 5.3 0.28 20.0 0.14 9.8 160 0.12 8.3 0.47 33.8 0.24 17.2 200 0.21 15.3 0.75 54.3 0.34 24.7 250 0.30 21.6 1.02 73.5 0.52 37.1 315 0.45 32.6 1.11 80.0 0.70 50.3 400 0.66 47.5 1.08 77.9 0.87 62.5 500 0.69 49.6 0.84 60.7 0.69 50.0 630 0.71 50.9 0.66 47.3 0.52 37.1 800 0.72 52.0 0.52 37.3 0.39 27.9 1000 0.74 53.3 0.42 29.9 0.30 21.3 1250 0.78 56.4 0.34 24.8 0.25 18.2 1600 0.83 60.1 0.30 21.3 0.28 19.9 2000 0.87 62.6 0.25 18.2 0.31 22.4 2500 0.92 65.9 0.22 15.7 0.25 17.9 3150 0.94 67.7 0.18 13.2 0.21 14.8 4000 0.98 70.2 0.15 11.0 0.18 13.3 5000 1.01 72.5 0.13 9.3 0.18 13.0

The average NRC and NRC values obtained for these AB and C tests are specified below in Table VI. Table VI- NRC values obtained for tests AB and C. Test A Test B Test C NRC Medium 0.65 0633 0455 NRC 0.65 0.65 0.45

The values of the sound absorption coefficients were obtained according to the terms of ASTM C 423-90a, by a Bruel Kjaer type 2133 analyzer.

The histograms of figures 8 , 9 and 10 represent the evolutions of the sound absorption coefficients for frequencies between 100 and 5000 Hertz, for tests A, B and C.

The flexible polymeric sheet material with improved acoustic properties which has just been described is suitable for use in tensioned structures for decoration or masking such as, in particular, false ceilings and false walls.

This material can also be used for billboards, of fixed or scroll type, the attenuation of the reverberation to reduce the noise generated by these panels.

As the visual aspect of the material is not substantially modified by the production of these micro-reliefs, this material remains perfectly adapted to use both in industrial and hospital environments, as well as for public facilities or modern living quarters. or historical.

The acoustic properties obtained using these materials are quite comparable to those of ceilings as shown in the table below, given as an indication. Table VII- Comparison of the acoustic properties of a micro-perforated sheet according to the invention and conventional ceiling plates. Product 125Hz 250Hz 500Hz 1000Hz 2000Hz 4000Hz CAA Suspended ceiling plate (Armstrong) 0.23 0.32 0.40 0.87 0.74 0.83 0.55 Suspended ceiling plate b (Armstrong) 0.34 0.32 0.40 0.64 0.71 0.76 0.55 Suspended ceiling plate c (Armstrong) 0.33 0.31 0.53 0.68 0.62 0.52 0.55 New Matte micro-perforated stretch fabric (assai 14) 0.27 0.35 0.45 0.58 0.70 0.63 0.50

Claims (9)

1. Polymer material (1) in a flexible sheet of a thickness (e1) of less than a half-millimetre, for the production of stretched constructions such as in particular suspended ceilings, characterised in that it comprises micro-reliefs extending over a height (h) from a few microns to 100 microns, micro-reliefs (2) formed by embossing the constituent matter of the material (1) which thus has a higher co-efficient of acoustic absorption than the same material without said reliefs, the microreliefs being obtained by a needling stage, locally embossing the constituent material of the sheet in a predetermined pattern until its microperforation, the needling stage being carried out when the material sheet is placed under a tension of the order of that of its final use in a stretched construction.
2. Material according to claim 1, characterised in that the height (h) of the micro-reliefs (2) measured in a direction perpendicular to the plane of the said sheet at the level of these micro-reliefs (2) is less than three times the thickness (e1) of said sheet.
3. Material according to claim 1 or 2, characterised in that the micro-reliefs (2) form projections on a single face of said sheet.
4. Material according to claim 3, characterised in that all these micro-reliefs (2) are arranged following the nodal points of a single pattern.
5. Material according to claim 4, characterised in that the pattern has a square mesh.
6. Material according to any of claims 1 to 5, characterised in that the density of the micro-perforations is between 2 and 60 per square centimetre.
7. Material according to any of claims 1 to 6, characterised in that it is selected from the group comprising plasticized polyvinyl chloride, vinylidene chloride and vinyl chloride/vinylidene chloride copolymers.
8. Material according to any of claims 1 to 7, characterised in that the area occupied by the micro-reliefs (2) is between 0.5% and 10% of the total area of said sheet.
9. Suspended ceiling, characterised in that it comprises a sheet of material as presented in any of claims 1 to 8, tensioned in relation to the support means.

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