FR2843120A1 - Polymer foam panel for sealing/soundproofing motor vehicles has thermoformed cavities filled with synthetic foam - Google Patents

Abstract

The panel (11) is made from a complex adhesive material comprising a layer of a polyolefin foam, preferably 2 - 4 mm thick, covered on at least part of one surface with a pressure-sensitive adhesive, and has thermoformed cavities (12a, 12b, 12c) filled with a synthetic foam. The pressure-sensitive adhesive is highly cohesive and is applied in a 50 - 150 mcm layer or as a bead, and the majority of the thermoformed cavities are conical in shape.

Description

The present invention relates to a flexible adhesive complex intended to insulate

  humidity and noise in compartments, especially in cars.

  PRIOR ART Various devices are already known, the function of which is to create a seal in the doors of automobiles so as to avoid infiltration of water or dust into the interior of the vehicle. Such devices are for example described in the documents US 5,595,415, US 6,197,403, US 6,412,852, EP 816,174. Devices are also known which combine films and foams in order to produce complexes which combine the properties film sealing and foam damper. For example, US Pat. No. 3,655,840 describes a process making it possible to obtain such an assembly, while document GB 2,002,673 describes a sound-absorbing complex based on foam.

polyurethane.

  FIELD OF THE INVENTION The invention relates to an adhesive complex of a new design, which can be fixed by gluing to walls or in boxes so as to obtain a water tightness and a soundproofing. This complex finds particular application for sealing car doors, but it can also be used to protect and soundproof other walls of vehicles, for example the

  engine compartment, trunk or even the roof pavilion.

  OBJECT OF THE INVENTION According to the invention, there is provided a new complex adhesive element consisting of a sheet of polyolefin foam with closed cells, thermoformed, covered on at least part of one of its faces with a layer of pressure-sensitive adhesive mass comprising cavities obtained by thermoforming in the

  foam sheets, and filled with synthetic foam material.

  According to a particular characteristic of the invention, the aforementioned polyolefin foam sheet is a sheet of non-crosslinked polypropylene foam with

closed cells.

  According to another particular characteristic of the invention, the aforementioned synthetic foam material filling the cavities is a polyurethane foam. According to a preferred embodiment of the invention, the pressure-sensitive adhesive mass is strongly cohesive and is in the form of a

  layer thickness between 50 and 150 µm.

  According to another embodiment of the invention, the pressure-sensitive adhesive mass is in the form of an advantageously foamed bead, deposited

  essentially on the periphery of the foam sheet.

  The invention also relates to a door sealing panel for an automobile produced using the aforementioned complex and its use to prevent infiltration of water and dust as well as to reduce incoming noise or

  reflected inside the cabin.

detailed description

  The production of the adhesive complex element according to the invention essentially calls for the assembly of 3 main constituents which are - a polyolefin foam sheet - a pressure-sensitive adhesive mass - a synthetic foam The polyolefin foam sheet must be thermoformable and waterproof. For this purpose, a closed cell foam sheet is preferably chosen, at least one of the faces of which has the appearance of skin. The material of this sheet is for example a non-crosslinked polypropylene, which has good thermoforming and mechanical strength characteristics. If necessary, the sheet material can be treated to be flame retardant, in applications

  particular requiring this property.

  The thickness of the polyolefin foam sheet is generally included

  between 1 to 8 mm, preferably between 2 and 4 mm.

  The pressure-sensitive adhesive material is, for example, an adhesive in the solvent phase in the case where it is desired to carry out a coating in a thin layer, or else an adhesive of the "hot melt" type, coated or deposited hot, without solvent. . In the case of adhesives in the solvent phase, use will preferably be made of adhesives of the acrylic type, having high cohesion. In the case of hot melt type adhesives, use will preferably be made of crosslinkable formulations in order to obtain significant cohesion of the adhesive mass. The adhesive material can be deposited by coating the molten mass using a nozzle, so as to obtain a layer of regular thickness, deposited directly on the foam sheet, or in the form of a foamed bead deposited by a nozzle by means of a robot on the periphery of the foam sheet. In the case of a thin layer coating, the adhesive mass is coated on the sheet prior to the thermoforming operation whereas in the case of a deposit in the form of a

  cord, this is made after the thermoforming operation.

  The synthetic foam used to fill at least part of the cavities created by thermoforming in the foam sheet is preferably a polyurethane foam which is generated by reaction, after injection, of the

  polyisocyanate and polyol precursors.

  For this purpose, components marketed and known to those skilled in the art will be used to form foams with open or semi-open cells, of low density and very flexible. The foaming reaction is carried out in a mold containing the thermoformed sheet, the mixture of components being prepared extemporaneously and injected into each of the cavities for example

by means of a robotic dispenser.

  The characteristics of the foam material can be improved by inclusion or mixture of additives such as for example a fungicide, a dye, a

  filler or a compound capable of generating or capturing odors.

  The manufacturing process of the complex adhesive elements according to the invention depends on the nature of the adhesive used. In the case of a coated adhesive mass, the method consists in previously coating the sheet of polyolefin foam on one of its faces with a layer of adhesive mass. When using an adhesive mass in the solvent phase, the coating can be carried out either directly (the adhesive mass solution is deposited with an even thickness directly on the sheet, then is dried by passage through a tunnel) or by transfer (the adhesive mass solution is coated on a temporary non-stick support, dried and then transferred to the foam sheet). In the case of an adhesive mass of the hot melt type, it is possible to proceed in a similar manner, but it is generally preferred to carry out a direct coating which makes it possible to obtain a stronger bond between the adhesive layer and the foam sheet due to the training

  a heat seal between the layers.

  Prior to coating the adhesive layer, it is advantageous to treat the foam sheet according to the CORONA process so as to improve the

  cohesion of Ilnterface sheet-adhesive.

  After coating, the adhesive-coated foam sheet is thermoformed on a vacuum mold, so as to give the sheet a third dimension and to form on the one hand, the abovementioned cavities and on the other hand, the shapes which will allow the object to adapt to its support. In order to create a wall capable of improving the acoustics of a vehicle, cavities are advantageously formed in the form of cones about 1 to 2 cm deep and 2 to 3 cm in diameter at the base. One can also form grooves which, after filling

  with the foam material, will increase the stiffness of the sheet.

  The thermoformed and adhesive-coated foam sheet is then placed in a mold adapted to its shape, then the mixture of the precursor constituents of the foam is injected into the above-mentioned cavities. The mold is closed by applying a counterform for the time necessary for the development of the foam. The part is then removed from the mold, then cut, if necessary, to give it its

final form.

  The choice of adhesives with strong cohesion is advantageous in that it allows a storage of the stacked parts without it being necessary to interpose between them

  an intermediate non-stick sheet.

  In the case of the use of an adhesive in the form of a foamed bead, the bead is deposited by means of a robot after the operations of

  thermoforming and filling of the foam material in the cavities.

  The complex adhesive elements according to the invention thus obtained can be used in particular as a sealing panel in the doors of motor vehicles. The addition of synthetic foam blocks in the cavities significantly improves the acoustic performance compared to

  previously used panels and locally increase the stiffness of the sheet.

  It is also possible, according to the same principle, to thermoformed and adhesive parts, intended to be integrated into stationary or mobile machines in order to dampen or filter noise. For example, such parts find their use in the construction of public works machines, agricultural machines, compressors, generators and in household appliances. The embodiments described below as well as the accompanying drawings, which should not be considered as limiting, will allow better

understand the subject of the invention.

  FIG. 1 represents a sectional view of part of an adhesive element (1) according to the invention, where there is a sheet of polyolefin foam (2) coated with a layer of adhesive mass (3) and thermoformed to form a

  conical cavity filled with synthetic foam material (4).

  FIG. 2 represents a top view of a sealing panel, for example for a car door, cut and thermoformed so as to obtain conical cavities (12a), or of various shapes (12b) or grooves (12c ). Figure 3a shows a sectional view along line BB 'of Figure 2 of the previous panel consisting of the sheet of thermoformed polyolefin foam (2), the foam material filling the cavities (4) and a layer adhesive mass (3) coated on the face opposite to that receiving the

foam material (4).

  3b shows a sectional view identical to Figure 3a of another embodiment showing a layer of adhesive mass (3) disposed on the face of the sheet receiving the foam material (4); FIG. 3c represents a sectional view identical to the previous ones, of yet another embodiment, in which the panel is adhesive-coated by means of strips (5) of adhesive material arranged essentially at the periphery

  of the panel and around the various openings made in the panel.

  FIG. 4 represents a sectional view along line CC ′ of the panel represented in FIG. 2 of an embodiment of the invention, in which a bead of adhesive material is placed on the top of a stiffening groove ( 12c).

Example 1

  A sheet of non-crosslinked polypropylene foam with a thickness of 2.2 mm and a density equal to 45 kg / m3 is used (ref. 530 supplied by the company PACTIV SENTINEL). This foam sheet is treated by the CORONA process on one of its faces then coated by transfer over the entire surface of the CORONA treated face with an adhesive mass sensitive to pressure of acrylic type in solvent phase (ref. XPE 376 supplied by the AV CHEMIE). The coating is adjusted to obtain a deposit of approximately 40 g / m2 of adhesive mass. The foam sheet thus adhered is then thermoformed on a vacuum mold so as to obtain, in addition to a shape adaptable to the structure of the door, semi-cylindrical, conical and parallelepipedal cavities regularly distributed on the sheet. The shaped sheet is then placed in a mold and a mixture of polyols (Lupranol supplied by the company BASF) and prepolymers of MDI (4,4′-methylenebis (phenylisocyanate)) is injected into each cavity (Lupranat supplied by BASF). The reaction between these two components produces a polyurethane foam in the shape of the mold. After demolding, the adhesive panel is obtained according to

  the invention, which is used for sealing a car door.

Example 2

  A sheet of non-crosslinked polypropylene foam is used, with a density equal to approximately 45 kg / m 3, with a thickness of approximately 3 mm, treated to be

  self-extinguishing (ref. PROXIL 45 low L 35H630 obtained from the company PROXITAL).

  This foam sheet is coated directly by means of a nozzle with an adhesive of the hot melt type crosslinkable under Ultra Violet radiation (reference adhesive Ac Resin A258 UV supplied by the company BASF). The adhesive-coated sheet is then thermoformed so as to obtain conical cavities which are then filled with polyurethane foam in a similar manner to that described in

Example 1.

Example 3

  This example is analogous to Example 1, except that the polyolefin foam sheet is here a crosslinked polyethylene foam sheet 2 mm thick and with a density equal to about 50 kg / M3, treated for be self-extinguishing.

Example 4

  According to this example, a polypropylene foam sheet similar to that used in Example 2 is used. This sheet is thermoformed to obtain conical cavities or of various shapes (in particular pyramidal trunks) then the cavities are filled with a foam of polyurethane according to a process analogous to that described in the previous examples. The sheet is then cut to obtain panels and then a foamed bead of hot melt adhesive mass is deposited on the peripheral parts of the panel and of certain cavities using a robot. The adhesive used is for example obtained from the company TIVOLI under the reference Tivomelt 9249/10. The panel thus obtained can be fixed to the walls of the engine compartment to protect and improve the general acoustics of a motor vehicle. These examples are described for applications in the field of automobile construction, but panels according to the invention can also be used in all cases where it is necessary to protect from humidity or to reduce noise in motorized vehicles. or in household appliances. The choice of polyurethane foams according to their flexibility and density also makes it possible to increase the rigidity of the panels without significantly increasing the weight and to create volumes capable of absorbing shocks and thus contributing to the protection of the occupants.

of the vehicle.

Claims (6)

  1) Adhesive complex element consisting of a sheet of polyolefin foam with closed cells, thermoformed, covered on at least part of one of its faces with a layer of adhesive mass sensitive to pressure characterized in that it includes cavities formed by thermoforming and   filled with synthetic foam material.   2) adhesive element according to claim 1, characterized in that the aforementioned polyolefin foam sheet is a polypropylene foam sheet not crosslinked.   3) adhesive element according to one of claims 1 or 2, characterized in that   the aforementioned synthetic foam material filling the cavities is a polyurethane foam.   4) adhesive element according to one of claims 1 to 3, characterized in that   the aforementioned pressure-sensitive adhesive mass is strongly cohesive and   in a layer thickness between 50 and 150pum.   ) Adhesive element according to one of claims 1 to 3, characterized in that   the aforementioned pressure-sensitive adhesive mass is in the form a cord.   6) adhesive element according to one of claims 1 to 5, characterized in that   that a majority of the thermoformed cavities are in the form of cones.   7) Use of an adhesive element according to any one of claims 1   to 6 for the manufacture of a sealing and / or soundproofing panel in motor vehicles.