FR3020782A1 - ACOUSTIC INSULATION PANEL - Google Patents

Abstract

The present invention relates to an acoustic insulation panel comprising at least two superimposed layers. Said panel is characterized in that the first layer is composed of a fiber mat and the second layer is composed of a needle-punched nonwoven fabric, said second layer comprising an outer face and an inner face in contact with said first layer said inner face having a plurality of points of powdered thermoplastic glue so as to bond the first layer to the second layer. The invention also relates to a method for obtaining such an acoustic insulation panel. Said panel provides optimum acoustic insulation, and is intended for an application in particular in the transport sector, particularly automotive.

Description

The present invention relates to the field of insulation, in particular acoustic insulation. The present invention will find its application mainly in the sector of the transport industry, in particular automobile, without being limited thereto. Indeed, the invention may also find application in the aviation or rail transport sector. The invention more particularly relates to a panel 10 of sound insulation. Traditionally, in the automotive sector, the acoustic insulation panels that are used are composed, on the one hand, of a bag made of a plastic material, such as polyurethane for example, containing hollow fibers, in 15 particular type of wadding. Thus, patent document EP 0 607 946 discloses a panel comprising an acoustic insulation material and used in the field of the transport industry, in particular the automobile. More particularly, it is a panel of non-woven acoustic insulation material, especially a nonwoven fabric comprising thermoplastic fibers, and allowing attenuation of sounds. The acoustic insulation panel may further include a second layer formed by a laminated metal sheet. However, the insulation panel thus obtained is difficult to hang in the vehicle because it has too much flexibility. In addition, the "mattress" of fibers is likely to move and settle in a corner, resulting in non-homogeneous sound insulation on the entire panel. In addition, the bag, or panel, is obtained from petroleum. Therefore, it releases formaldehyde. For safety reasons, it can not therefore be placed inside the passenger compartment, for example the vehicle.

Another disadvantage of the panel described in this document lies in the fact that it is likely to make noise when it is positioned near a sheet and that it comes into contact with it, for example by friction.

The invention offers the possibility of mitigating, at least in part, the various disadvantages of the state of the art by proposing an acoustic insulation panel which notably allows an improved attenuation of the sounds compared to existing panels in the state of the art. the technique.

In addition, the acoustic insulation panel according to the invention responds, particularly advantageously, to other important technical considerations. Thus, said panel has in particular: interesting mechanical characteristics; - homogeneous acoustic insulation; - no release of harmful products such as formaldehyde; - satisfactory fire resistance; - good hydrophobicity, particularly interesting when used in wet conditions; - optimum resistance to high temperatures, up to at least 215 ° C. Said panel also has excellent flexibility, due to a suitable compromise between rigidity and flexibility, allowing adaptation of said panel to three-dimensional shapes. In addition, the panel according to the invention is entirely recyclable. Also, interestingly, the acoustic insulation panel according to the invention is more economical to produce than the traditional panels of the state of the art consisting of bagged fibers. Thus, the present invention relates to an acoustic insulation panel comprising at least two superimposed layers 35.

Said panel is more particularly characterized in that the first layer is composed of a fiber mat and the second layer is composed of a needle-punched nonwoven fabric, said second layer comprising an outer face and an inner face in contact with said first layer, said inner face having a plurality of points of powdered thermoplastic glue so as to bond the first layer to the second layer. According to other optional features of the invention: the fiber mat of the first layer is composed of polyester, preferably polyethylene terephthalate; the first layer has a basis weight of between 350 and 450 g / m2, preferably equal to 400 g / m2; the first layer has a thickness of between 15 and 30 mm, preferably between 19 and 25 mm, preferably equal to 22 mm; the flammability of the first layer is less than or equal to 120 mm / min, preferably less than or equal to 100 mm / min; the needled nonwoven fabric of the second layer is composed of polyester; the second layer has a grammage of between 50 and 150 g / m 2, preferably between 90 and 110 g / m 2, preferably equal to 100 g / m 2; the second layer has a thickness of between 0.50 and 1.0 mm, preferably equal to 0.60 mm; the second layer has a tensile strength in the longitudinal direction greater than or equal to 70 N / 5 cm, preferably greater than or equal to 90 N / 5 cm and a breaking strength in the width direction greater than or equal to 100N / 5cm, preferably greater than or equal to 120N / 5cm, said second layer further having an elongation at break in the length direction greater than or equal to 35%, preferably greater than or equal to 45% and an elongation at break in the width direction greater than or equal to 45%, preferably greater than or equal to 55%; - The edges of the first layer and the second layer are welded over the entire outer periphery of said panel. The invention also relates to a method for obtaining an acoustic insulation panel, said method comprising the following steps: - the first layer composed of a fiber mat is superimposed and the second layer composed of a nonwoven fabric needled and whose inner face has a plurality of points of thermoplastic powder glue; these layers are positioned at a shaped punch corresponding to the shape of the acoustic insulation panel that is to be obtained; the die as well as the first layer and the second layer are deposited on a tray held at a high temperature; the layers are cut and the edges of said layers are welded simultaneously by hot compression. Other characteristics and advantages of the invention will emerge from the following detailed description of non-limiting embodiments of the invention, with reference to the appended figures in which: FIG. 1A illustrates a particular embodiment of FIG. a front view of the outer face of the first fiber mat layer of the insulation board according to the invention and FIG. 1B illustrates a particular embodiment of a front view of the outer face of the second layer. insulation board made of needle-punched nonwoven fabric; FIG. 2 schematically represents a cross-sectional view of the acoustic insulation panel 35 according to the invention, on which are visible the first layer and the second layer of said panel, as well as the internal and external faces of each said layers, the inner face of the second layer having a plurality of points of glue so as to allow a connection between the two layers of the panel; FIG. 3 corresponds to a graph illustrating the alpha absorption coefficient of an insulation panel according to the invention (curve No. 1), in comparison with five other insulation panels existing in the state of the art ( curves # 2 to # 6). The absorption coefficient of the panels, in percentage, is represented here according to the frequency of the sound waves passing through said panels. As shown in Figures 1A and 1B, the present invention relates to an acoustic insulation panel 1 comprising at least two layers, a first layer 2 shown in light color in Figure lA and a second layer 3 shown in Figure 1B. More particularly, in these figures 1A and 1B, they are in dark color on the represented the outer faces 21 and 31 respectively of the first layer 2 and the second layer 3. The edges 23 and 33 of the layers 2 and 3 respectively, are also visible in Figures 1A and 1B. The first layer 2 preferably consists of polyester and advantageously consists of a textile fiber mat. Preferably, the first layer 2 is composed of PET, or poly (ethylene terephatalate), which consists of a saturated polyester type plastic. PET can in particular be obtained by polycondensation of terephthalic acid with ethylene glycol. According to an interesting embodiment, the first layer 2 of the insulation panel 1 has a basis weight of between 350 and 450 g / m 2. More preferably still, the basis weight of said first layer is substantially equal to 400 g / m 2. The thickness of the first layer 2 of textile fibers is preferably between 15 and 30 mm, more preferably between 19 and 25 mm, and more preferably, the thickness of said layer 2 is substantially equal to 22 mm. Advantageously, the flammability of the first layer 2 of the panel 1 is less than or equal to 120 mm / min, and more advantageously still less than or equal to 100 mm / min. Such technical characteristics advantageously contribute to reinforcing the acoustic insulation permitted by the insulating panel 1 according to the invention, as well as certain of its mechanical characteristics. Finally, said first layer 2 is preferably light in color, for example white in color, as illustrated in FIG. 1A, while the second layer 3 advantageously has, for its part, a darker color, for example black, as can be seen in FIG. 1B. With regard to the second layer 3, this is also advantageously made of polyester, and more particularly of needle-punched nonwoven polyester fabric. Non-woven textile is a textile whose fibers are held randomly. More particularly, a nonwoven fabric is defined as a manufactured product consisting of a web, a web, or a fiber mat, whether these are distributed directionally or by chance. The internal cohesion of the nonwoven fabric is ensured by various methods, these being either mechanical or chemical, but excluding weaving and knitting. Thus, in particular, the needling technique is used to allow the mechanical consolidation of a nonwoven fabric. This technique aims to create vertical fiber bridges between the different plies to hold them together. For this reason, needling can only be applied to fibers having a length greater than 40mm.

As regards the thickness of the second layer 3 of the insulating panel 1, it is preferably between 0.50 and 1.0 mm, and more preferably substantially equal to 0.60 mm.

In a particular embodiment, the weight of said second layer 3 is between 50 and 150 g / m 2, preferably between 90 and 110 g / m 2 and, more preferably, said basis weight is substantially equal to 100 g / m 2. With regard to the technical specificities of the second layer 3 of the panel, this advantageously has: - a breaking strength in the length direction greater than or equal to 70N / 5cm, preferably greater than or equal to 90N / 5cm; a breaking strength in the width direction greater than or equal to 100 N / 5 cm, preferably greater than or equal to 120 N / 5 cm; an elongation at break in the length direction greater than or equal to 35%, preferably greater than or equal to 45%; An elongation at break in the width direction greater than or equal to 45%, preferably greater than or equal to 55%. In particular, the second layer 3 of needle-punched nonwoven fabric of panel 1 may be advantageously sprinkled with polyester. Returning now to the acoustic insulation panel 1 as such, the second layer 3 of said panel 1 is in contact with the first layer 2 via the inner face 32 of said second layer 3. The face internal 32 of the second layer 3, as well as the inner face 22 of the first layer 2, are shown in Figure 2 attached. In this same figure, it is visible that the first layer 2 and the second layer 3 of the acoustic insulation panel 1 according to the invention are in contact at their respective inner faces 22, 32.

The layers 2 and 3 of the insulation panel 1 are bonded by means of a plurality of points of powdered thermoplastic glue 4, said points 4 being distributed at the inner face 32 of the second layer 3 of needle-punched nonwoven fabric . The points of thermoplastic powder glue 4 are distributed indifferently at the inner face 32 of the second layer 3 of the panel 1. Thus, said points 4 can be evenly or randomly distributed over said inner face 32. preferably, the points of thermoplastic powder glue 4 are distributed, regularly or randomly, over the entire surface of the inner face 32 of the second layer 3 of nonwoven needle-punched fabric. The use, for the realization of the acoustic insulation panel 1 according to the invention, of a needle-bonded nonwoven fabric associated with a thermoplastic binder in powder form, distributed in the form of points 4, advantageously makes it possible to avoid an effect " on the said panel 1. As a result, the insulation board 1 remains air permeable, which allows the sound to penetrate into the fibers of said panel 1, especially the textile fibers of the mattress of the first layer 2 and the fibers of the needled nonwoven fabric of the second layer 2, thereby generating effective sound attenuation. This prevents the sounds "slip" on the panel 1 without penetrating, which does not allow a satisfactory sound insulation, and accordingly allows a satisfactory absorption of sounds by said acoustic insulation panel 1. The Sound absorption refers to the ability of a material to absorb incident sound waves, while transmission loss relates to the ability of a material to reflect incident sound waves.

High sound absorption is considered interesting for the sound insulation of a panel, as well as a significant loss of transmission. The attached figure 3 corresponds to a graph representing the absorption coefficient of the sound waves (in ordinates, expressed in percentages) according to the frequency of the latter (in abscissas, expressed in hertz - Hz), and this for different acoustic insulation panels, including panel 1 according to the invention, on curve No. 1.

Curve No. 2 illustrates the results obtained for a panel whose properties are considered to be very satisfactory for an acoustic insulation of vehicles. Finally, the curves numbered from 3 to 6 represent the sound absorption for various other acoustic insulation panels conventionally used by automobile manufacturers. The graph of this FIG. 3 clearly shows that the insulating panel 1 according to the invention has a substantially improved sound absorption compared with panels Nos. 3, 4, 5 and 6 known from the state of the art, particularly when the sound waves have a frequency higher than 1250Hz. In addition, said insulation panel 1 also has acoustic properties similar to those of acoustic panel No. 2 considered to be the reference on the market, up to a frequency of sound waves of the order of 4000 Hz. Above 4000 Hz, the acoustic panel 1 according to the invention shows a better sound absorption compared to the reference panel No. 2. However, in addition to optimal sound absorption, the acoustic insulation panel 1 according to the invention also makes it possible to respond to other important technical considerations, which makes it all the more interesting for many applications. Thus, the acoustic insulation panel 1 according to the invention has no risk of release of harmful products, such as formaldehyde, no smell, and is little or not subject to phenomena of fogging (low fogging) , which advantageously allows to avoid the presence of steam in the passenger compartment of the vehicle. All of these characteristics confer on said panel 1 a particular interest for an application inside the passenger compartment of a vehicle, in particular a car. The panel 1 also shows optimum hydrophobic properties. Therefore, said panel 1 can be used in a wet area, for example the outer side of the passenger compartment of the vehicle. Also, the acoustic insulation panel 1 according to the invention has optimum resistance to high temperatures, up to at least 215 ° C. In comparison, the insulation panels known in the state of the art have satisfactory behavior up to a temperature of the order of 140 ° C. As a result, unlike the existing panels, the acoustic insulation panel 1 according to the invention can be used to allow insulation in places where the temperature is particularly high, for example near the engine of a vehicle. . Interestingly, the edges 23, 33 respectively of the first layer 2 and the second layer 3 of the panel 1 are welded to the entire outer periphery of said panel 1, as shown in Figures 1A and 1B. This advantageously makes it possible to prevent the fibers of the first layer 2 from coming out of the insulating panel 1 according to the invention. In other words, it avoids the risk of pollution by the fibers. In addition, the welding of the edges 23, 33 gives said panel 30 1 a rigidity on the whole of its outer periphery, which leads to an improvement in mounting said panel 1 inside the passenger compartment of a vehicle. The present invention also relates to a method for obtaining an acoustic insulation panel 1 according to the invention.

In this process, the following steps are carried out: - the two layers 2, 3 of the insulation panel are superimposed, namely the first layer 2 composed of a fiber mat and the second layer 3 of nonwoven needle-punched fabric , the latter having, at its inner face 32, a plurality of points of thermoplastic glue powder 4; positioning said layers 2.3 superimposed at the level of a cutting tool, for example a die-cutting tool; the latter advantageously has a shape corresponding to that of the panel 1 that it is desired to obtain; said die incorporating the superimposed layers 2, 3 is deposited on a tray held at a high temperature; - The first layer 2 and the second layer 3 which are superimposed in the punch are cut and the edges of said layers 2, 3 are welded; the cutting of the layers 2, 3 and the welding of their edges are carried out simultaneously by the hot compression technique. Preferably, said plate, on which is deposited the die containing the layers 2, 3, is maintained at a temperature between 100 and 200 ° C, and more preferably between 120 and 130 ° C. The method according to the invention advantageously makes it possible to obtain an insulating panel 1 whose edges are rigid, which consequently makes it possible to stiffen the whole of said panel 1, while the inner surface of the layers 2, 3 remains flexible. Thanks to this optimal compromise between rigidity and flexibility, the acoustic insulation panel 1 according to the invention can be easily adapted to three-dimensional shapes. Indeed, the inner flexibility of said panel 1 gives it an interesting ability to match the unevenness of the supports at which it must be positioned in the vehicle. In addition, it is also conceivable to "partition" the panel 1 according to the invention, by performing a welding step at least a portion of the inner surface of the layers 2, 3, and this in order to For example, form a right angle. Of course, the invention is not limited to the examples illustrated and described above which may have variants and modifications without departing from the scope of the invention.

In particular, it may be possible to envisage an acoustic insulation panel 1 comprising, in addition to the first layer 2 of fiber mat and the second layer 3 of nonwoven fabric, at least one third layer.

Claims (12)

REVENDICATIONS1. Acoustic insulation panel (1) comprising at least two superposed layers (2,3), characterized in that the first layer (2) is composed of a fiber mat and the second layer (3) is composed of a needle-punched nonwoven fabric, said second layer (3) comprising an outer face (31) and an inner face (32) in contact with said first layer (2), said inner face (32) having a plurality of points of thermoplastic glue in powder (4) so as to bond the first layer (2) with the second layer (3). Soundproofing panel (1) according to claim 1, characterized in that the fiber mat of the first layer (2) is composed of polyester. 3. acoustic insulation panel (1) according to the preceding claim characterized in that the fiber mat of the first layer (2) is composed of poly (ethylene terephatalate). 4. acoustic insulation panel (1) according to any one of the preceding claims characterized in that the first layer (2) has a basis weight between 350 and 450g / m2, preferably equal to 400g / m2. 5. acoustic insulation panel (1) according to any one of the preceding claims characterized in that the first layer (2) has a thickness between 15 and 30mm, preferably between 19 and 25mm, preferably equal to 22mm. Soundproofing panel (1) according to any one of the preceding claims, characterized in that the flammability of the first layer (2) is less than or equal to 120 mm / min, preferably less than or equal to 100mm / min. Soundproofing panel (1) according to any one of the preceding claims, characterized in that the needle-punched nonwoven fabric of the second layer (3) is composed of polyester. Soundproofing panel (1) according to any one of the preceding claims, characterized in that the second layer (3) has a grammage of between 50 and 150 g / m 2, preferably between 90 and 110 g / m 2, preferably equal to 100g / m2. 9. acoustic insulation panel (1) according to any one of the preceding claims characterized in that the second layer (3) has a thickness between 0.50 and 1, mm, preferably equal to 0.60 mm. 10.An acoustic insulation board (1) according to any preceding claim characterized in that the second layer (3) has a breaking strength in the length direction greater than or equal to 70N / 5cm, preferably greater than or equal to 90N / 5cm and a breaking strength in the direction of the width greater than or equal to 100N / 5cm, preferably greater than or equal to 120N / 5cm, said second layer (3) further having an elongation at the lengthwise breaking greater than or equal to 35%, preferably greater than or equal to 45% and elongation at break in the width direction greater than or equal to 45%, preferably greater than or equal to 55%. Soundproofing panel (1) according to one of the preceding claims, characterized in that the edges (23,33) of the first layer (2) and the second layer (3) are welded to one another. the entire outer periphery of said panel (1). 12.Procédé to obtain an acoustic insulation panel (1) according to any one of the preceding claims characterized in that it comprises the following steps: the first layer (2) is composed of a mattress of fibers and the second layer (3) composed of a needle-punched nonwoven fabric and whose inner face (32) comprises a plurality of points of thermoplastic powder glue (4); said layers (2, 3) are positioned at a shaped punch corresponding to the shape of the acoustic insulation panel (1) that is to be obtained; the die as well as the first layer (2) and the second layer (3) are deposited on a tray held at a high temperature; the layers (2, 3) are cut and the edges of said layers (2, 3) are welded simultaneously by hot pressing.