WO2004104133A1

WO2004104133A1 - Method for production of a sealing joint gasket

Info

Publication number: WO2004104133A1
Application number: PCT/EP2004/005335
Authority: WO
Inventors: Laurent Jeanmart; Yves Lehmann; Dimitri Leroy
Original assignee: Saint-Gobain Performance Plastics Chaineux S.A.
Priority date: 2003-05-22
Filing date: 2004-05-18
Publication date: 2004-12-02
Also published as: KR20060025530A; FR2855230B1; JP2007502354A; EP1646699A1; FR2855230A1

Abstract

According to the invention, the method for production in situ of a sealing joint gasket between a first element and a second element, is characterised in that one element selected from a first and a second element is provided with a sealing joint gasket (4) with a given form and section. Said sealing gasket is characterised by a high flexibility and a strongly hydrophobic, but non-siliconised surface, giving the piece excellent water-tightness.

Description

METHOD FOR MANUFACTURING A SEAL CORD

The present invention relates to a method of manufacturing a sealing bead, suitable for assembling a modular element and ready to be secured to a frame or other surface. The current trend, particularly in the field of motor vehicles, is to facilitate the mounting of the vehicle by reducing the number of assembly operations on an assembly line, equipment and / or accessories integral with the modular element having been pre-assembled in a separate workshop or unit. Thus, there are known modular elements for vehicle door, which are generally in the form of cover flange which are adapted to come to cooperate at the internal face of the vehicle door, in order to hide and protect for example the door closing mechanisms and / or the mechanisms ensuring the movement of the side panes within the door.

The modular element is generally fixed to a door element by screwing, or by means of interlocking and it is necessary, that at the interface between the modular element and the door element, to interpose a seal in order to preserve the volume located inside said door, from environmental damage (humidity, dust, vibration, etc.).

To this end, it is known to interpose, as a seal, at the interface between the two elements to be joined, a bead of foamed polymer seal.

Although this foamed seal best fulfills its sealing function when the door element and the modular element cooperate perfectly with each other, it sometimes happens that, despite an optimal connection between the two opposite elements, the bead of joint is not sufficiently compressed over its entire periphery and a breach is opened, creating a possible passage to environmental aggressions. This is usually consecutive to variations in the dimensional tolerances of manufacture of the door element and / or of the modular element, these tolerances being able to be minimal simultaneously.

In order to remedy this lack of tightness, in particular with regard to liquids such as water, it is customary to compress the foam seal with a compression ratio greater than at least 30% and to use seals with high deflection which maintain intimate contact between the door element and the modular element.

However, these compression ratios, following the tightening of the elements, and these relatively high deflections due to the material, can lead to surface deformations, or appearance defects, at the opposite zones.

In order to allow the shortest possible mounting time for these modular elements, it appears desirable to pre-equip them with sealing means on line in a limited time.

The object of the present invention is to propose a method of preparing modular elements provided with sealing means, capable of being stored for a certain period, in order to be able to be mounted directly on a frame or any other receiving surface, in particular an element of door with a limited number of operations.

The sealing means should be as effective as possible to guarantee a tightness, at low compression force, in particular with regard to liquids between the modular element and the opposite receiving surface.

"^' This object, as well as others which will appear subsequently, has been achieved with a process for producing a seal bead between a first element and a second element, characterized in that it is provided an element chosen from the first and second elements of a sealing bead of defined shape and section, obtained by the mixture of a polyol compound and an isocyanate compound, comprising a flexible elastic part, said a sealing bead with a hydrophobic skin.

Thanks to the manufacture of a flexible and hydrophobic sealing bead, it is possible to guarantee a perfect seal between the two elements even with a reduced assembly force.

In preferred embodiments of the invention, it is possible optionally to have recourse to one and / or the other of the following arrangements: - the skin consists of a layer attached to the elastic part,

- the skin came from production with the elastic part,

the seal bead is formed by extrusion of a single-component product, the seal bead is formed by co-extrusion of the elastic part and of the skin,

the sealing bead is formed in an extrusion head by the reaction of at least two components brought separately within said extrusion head, the skin is based on hydrophobic polyol,

the hydrophobic polyol comprises hydrocarbon chains such as fatty acids,

the skin is formed from a thermoactivable, photoactivable or chemoactivatable compound, the elastic part (5) has a relative density of less than 0.5, in particular of the order of 0.1 to 0.4,

- The sealing bead has a compression force of the order of 0.3 to 2 N per cm, preferably between 0.5 to 1.5 N per cm.

According to another aspect of the invention, the latter also relates to an element, such as in particular a motor vehicle door module, ready to be secured to a frame or other surface, which is characterized in that the element is provided of a sealing bead of determined shape and section, said of a sealing bead comprising at least one part a flexible elastic part obtained by the mixture of a hydrophobic polyol compound and an isocyanate . The sealing bead can fulfill a damping function, vis-à-vis the sounds contributing to the soundproofing of the assembly or vis-à-vis shocks or stresses by absorbing shocks or possible mechanical deformations. It can also catch up with tolerances on the dimensions of a bodywork. As a variant, a protective film, even if it is not compulsory, can be applied to avoid soiling the external surface of the seal bead with dust which could damage the seal.

As a film, use may be made of a plastic film, in particular of polyethylene, polyester, polyvinyl chloride or vinylidene, polyamide, coated or not with a layer of silicone. According to another variant of the invention, the external part of the sealing bead can have an adhesive power on the surface.

The connection between the first and second elements is carried out as follows: After having developed the sealing bead according to the invention by a manufacturing process which will be explained in more detail below, the external surface is made to cooperate of the sealing bead at one of the facing faces belonging to the first or second element, the elastic part of the sealing bead then being stressed or mechanically deformed (for example in compression, in extension, in shear) between the two elements which are brought together and immobilized by any means (screws, "clipping", fitting).

The method according to the invention makes it possible to conform a joint bead., Sealing making it possible to reproduce a sealing pattern between two elements, advantageously when this pattern is a closed curve which notably follows at least part of the periphery of the modular element. The method also makes it possible to also conform the section of the sealing bead so that it adapts perfectly in the space reserved for it in the final assembly, taking into account its capacities to deform. According to one embodiment, the seal bead is formed directly on one of the first or second elements.

Using an extrusion process, a single-component or multi-component product is deposited, this product having to form the elastic part of the sealing bead. In the case of a product with several components, the seal can be formed, in an extrusion head, by reaction of at least two components brought separately within said extrusion head.

When the elastic part of the sealing bead has formed, that it has reached its desired section and its mechanical characteristics in terms in particular of flexibility, surface condition, hardness, compression ratio, it has then a bonding surface. This connecting surface is intended to cooperate at the level of a contact zone of the other modular element (the first or the second). The cooperation takes place by mutual approximation of the facing surfaces of each of the elements, taking care to compress the elastic part of the joint so as to seal the assembly, which is then made integral by any known means (screws for example).

According to another embodiment different from the previous embodiments, the seal bead can be formed by depositing a moldable product on the layer forming the elastic part in the mold cavity. Depending on the method of obtaining the modular element used, we can then:

- Either form the sealing bead in one piece with one of the modular elements, it is therefore possible to mold the modular element (or at least a portion of the latter) directly on the sealing bead so as to simultaneously realize the modular element (or the modular element portion) and the composite sealing bead.

- Either form the cord of the modular element separately, one can either transfer the composite cord to a prefabricated modular element, or mold .. the modular element in contact with the sealing bead in said cavity. The moldable product can be placed in a closed mold by injection of a liquid. It is also possible to proceed in a mold cavity by extrusion (or other suitable method of distribution) of a viscous or pasty material, using mobile distributing means the mold being fixed, or else fixed distributing means the mold then being mobile. In the case where the elastic part of the sealing bead is protected by a peelable film, the moldable material is chosen from those whose modulus of elasticity in the uncrosslinked state is sufficient to allow the peeling of the film without tearing of the elastic part of the sealing bead. Such materials include in particular moisture-crosslinkable systems capable of being protected by an anti-humidity barrier film, in particular systems of the mono-component polyurethane type, preferably thermoplastic, optionally modified with an elastomer. Such a system is a polyurethane pre-polymer with a backbone of polyester, polyether or polyolefin type, obtained for example from a polyol and a hydrophobic isocyanate, at least one of which comprises a polymer or oligomer backbone such as supra.

As a variant, the composite sealing bead can be formed by depositing in the mold cavity the elastic part of the sealing bead sealing previously formed, in particular molded, the superposition of the two parts in another mold allowing the precise shape of the sealing bead to be controlled. In this variant, the elastic part of the previously formed seal bead can be an integral part of a modular element (or a portion of the latter) produced by molding.

Such a seal bead can be manufactured in particular by co-extruding a skin if necessary on at least one of the faces of the elastic part of the seal bead, the co-extrusion product being able to be deposited. in a mold cavity to take its final shape. By co-extrusion is understood here as well the formation of the elastic part of the sealing bead simultaneously with the deposition of a skin forming a tight surface around the body formed by the elastic part by means of a head. extrusion supplied with at least two extrudable materials, the application of at least one material forming the skin in an extrusion head through which the elastic part of the previously formed seal bead passes, particularly by extrusion.

A manufacturing process consists in depositing for example in a mold cavity a moldable material constituting the elastic part of the sealing bead, (this elastic part possibly being covered by an envelope forming a skin) and then pressing the one of the first or second elements against the elastic part of the sealing bead to errlprisoner the sealing bead on said modular element. Then, it is optionally possible to at least partially harden the elastic part of the seal bead in this mold thus closed by the modular element, before removing said modular element on which the composite seal bead is fixed. The curing of the sealing bead can be carried out or completed outside the mold by cooling or by reaction with air humidity.

The method according to the invention allows the mass production of modular elements ready to be mounted, this manufacture can be automated. The final assembly of these modular elements is very rapid and responds to the need to reduce the assembly time of assemblies such as motor vehicles.

Other details and advantageous characteristics will emerge below in the reading of the description of illustrative, but nonlimiting examples of the invention, made with reference to the appended drawings in which:

- Figure 1 shows a perspective view of the assembly of a door module on a car door; - Figure 2 shows a sectional view of the border area of the door module equipped with a seal bead according to a first embodiment;

- Figure 3 shows a sectional view of the border area of the door module equipped with a seal bead according to a second embodiment;

- Figure 4 shows a sectional view of the border area of the door module equipped with a seal bead according to a third embodiment;

- Figure 5 illustrates the evolution of the compressive force as a function of the compression ratio for 2 sealing beads.

First of all, it should be pointed out that for the sake of clarity the relative proportions between the different elements represented are not respected.

FIG. 1 shows a perspective view of a first element in particular a door 1 of a motor vehicle equipped with a second element in particular a door module 2 attached to a surface 3 or frame belonging to said door 1.

The door module 2 is shown in the unassembled position to make visible its face which is directed towards the surface 3 of the door 1 of the vehicle. To simplify the reading of the figure, no accessory or equipment is shown on the door module, but it goes without saying that all the usual equipment such as a pocket, etc. can be integrated into this module.

The door module 2 is mounted on the surface 3 of the door 1 by interposing between the internal face of the door module 2 and the surface 3 of the door 1 a bead of flexible sealing gasket 4. In this case the seal pattern is in the form of a closed frame running along the periphery of the door module. The gasket bead 4 must seal, in particular with liquid, between the door module 2 and the door 1 and can also exert other functions such as absorption of vibrations between the interior space and the external space delimited by these two parts as well as the fixing between the two elements.

The structure of the seal bead 4 is according to the invention and can be seen in FIG. 2 which also shows the structure of the module 2. In this figure, the module is shown as it is before mounting on the vehicle.

The seal bead 4 is formed of an elastic part 5 linked to one of the first or second elements. This elastic part 5 is very flexible. The sealing bead 4 has a section calibrated as a function of the authorized spacing between the first and second elements. Here the section is shown to be substantially square but may be quite different. To fulfill the sealing function, and to compensate for the manufacturing tolerances of the bodywork, the elastic part 5 of the sealing bead 4 is made of a viscoelastic material.

This visco-elastic part has a preferred composition which is as follows (all the proportions are expressed by weight):

According to a first composition, hereinafter called composition 1, the part 5 of the seal bead 4 can be based

- Hydrophobic polyol based on fatty acid (MM: 1700) (g): 50

- Polyetherpolyol (MM: 4000) (g): 20 - Polyetherpolyol (MM: 8000) (g): 25

- Polyetherpolyol (MM: 480) (g): 5 ^" - Distilled water (g): 1

- Silicone surfactant (g): 1

- Triethylene diamine (catalyst) (g): 0.6 - Carbon black / diisodecylphthalate DIDP (20/80) (g): 2

- polymer diphenylmethane diisocyanate (MDI) (g): 31

This joint has the following properties:

- Density (Kg / m ³ ): 200

- Hardness (Shore 00): 20

- Compressive strength (30%) (N / cm): 0.6 Pa.s

The elastic part of the sealing bead has a density of less than 0.5, in particular of the order of 0.1 to 0.4. The elastic part has a compression force of about 0.3 to 2 N / cm, preferably between 0.5 to 1.5 N / cm.

According to an alternative embodiment shown in Figure 3, the elastic part

5 of the joint bead has a central part 5a or core and a skin 5b. This part 5b is strongly hydrophobic. It may also be that the skin 5b

(cf. composition 3 below) covers a core 5a which is produced from an intrinsically hydrophobic composition (cf. composition 2 below).

Thus, according to a second composition hereinafter called composition 2, the core 5a is based on - Polyetherpolyol (g): 50

- Polyetherpolyol (MM: 4000) (g): 50

- Polyetherpolyol (MM: 480) (g): 12.8

- Distilled water (g): 2

- Silicone surfactant (g): 1 - Triethylene diamine (catalyst) (g): 0.6

- Carbon black / DIDP (20/80) (g): 2

- Polymeric MDI (g): 50.1

and has the following properties:

- Density (Kg / m ³ ): 125

- Hardness (Shore 00): 26

- Compressive strength (30%) (N / cm): 0.8 Pa.s

According to yet another composition hereinafter called composition 3

The skin 5b is based on

- Hydrophobic Polyol (MM: 1700) (g): 100

- Silicone surfactant (g): 0.5 - Triethylene diamine (catalyst) (g): 0.3

- Carbon black / DIDP (20/80) (g): 2

- Polymeric MDI (g): 16.8

And has the following properties

- Density (Kg / m ³ ): -1050

- Water absorption: <0.1% These compositions 1 and 2 and 3 are to be compared with the composition called 4 and which relates to a bead of seal according to the prior art. This composition 4 is based on Dynafoam 512G sold by the applicant company. This composition 4 has the following properties:

Density: 340 Kg / m ³

Hardness (shore 00): 45

Compressive strength (30%) (N / cm): 2.1

If leak tightness tests are carried out according to the U-test standard (Ford WSB-M3G102-B) for the various compositions 1, 2, 3 and 4, we find:

All the sealing cords included in the various examples pass PU-test with the exception of composition 2, the polyols of which are 100% polyetherpolyols.

On the other hand, when this product (composition 2) is coextruded with another product composed of 100% hydrophobic polyol so as to form a hydrophobic skin (composition 3), the flexible sealing bead thus formed passes the U- test. Consequently, the addition of a hydrophobic skin makes it possible to impart tightness to this cord.

It can also be seen that the sealing cords formed from examples 1 and 3 are much more flexible than the Dynafoam 512G and are waterproof at an identical compression rate (30%) which means that the effort to compress these cords sealing will be significantly less. We can refer to this effect in Figure 5.

Since these 2 products are waterproof to 30% compression (pass PU-test), the effort to compress the flexible sealing bead (according to composition 1) will be significantly less than for the Dynafoam 512G. For the graph in Figure 5, the compression speed of the joint is

2mm / min.

In the exemplary embodiment shown in FIG. 4, the elastic part 5 (more precisely its skin 5b) is protected by a film 6, allowing very long-term storage with placement on the receiving part. The purpose of the film 6 is generally to prevent, during the storage period at the module manufacturer or at the automobile manufacturer, that dust comes to contaminate the sealing bead and to avoid any contact with a surface other than the final assembly surface which would cause JJΠ damage to the elastic part 5. It also has the function of protecting the elastic part against external conditions, in particular humidity, light, oxygen.

The manufacture of the sealing bead can be obtained for example as follows:

In the cavity of a mold, there is a film 6 whose face in contact with the mold (which will be the external face of the film, once the cord 4 is finished) can be made of polyethylene to act as a release agent for the molded material. According to a variant not shown in the figures, the film 6 is deposited by spraying. On the internal face of the film 6, the material of the elastic part 5 of the sealing bead is deposited, for example by means of an extrusion nozzle which is moved along the cavity in a closed circuit. (provision can also be made for the extrusion nozzle to remain stationary and for the mold to move relative to the nozzle). In this way, a bead 4 can be formed in the form of a frame without discontinuity, therefore causing no leakage. The nozzle may have a section calibrated to give a preliminary shape to the material of the elastic part 5 of the bead 4, which ends up being shaped in the mold cavity.

As soon as the material of the elastic part 5 of the seal bead 4 is removed, the composite seal bead can be installed on the door module, by transfer onto the latter: the module of door against the external surface of the cord 4 not yet hardened and the material spontaneously adheres to the surface of the module. As a variant, it is possible to apply to the external surface of the elastic part 5 of the gasket bead 4 whether or not hardened (if the material of the bead 4 does not spontaneously adhere to the material of the module 2) a layer of adhesive, optionally .

After a longer or shorter exposure time depending on the materials used, the door module 2 can be removed from the surface of the mold with the composite bead 4 linked to its surface. The film 6, if it exists, is also extracted from the mold cavity and remains attached to the elastic part 5 or to its skin 5b which it immediately protects from dust and / or moisture.

The module 2 thus equipped with the sealing bead 4 can be maintained for a time sufficient for hardening or the acquisition of the structural properties of the bead 4, then stored while awaiting its use for mounting on a vehicle. The assembly is carried out simply by removing the protective film 6, after which the cord 4 is placed in contact with the door of the motor vehicle.

Alternatively, the seal bead 4 is formed directly on one of the first or second elements.

To this end, a mono-component or multi-component product is deposited directly on one of the faces of said element and according to the desired sealing pattern, this product having to form the elastic part 5 (5a and 5b) of the bead of seal 4. In the case of a product with several components, the seal 4 can be formed, in an extrusion head, by reaction of at least two components brought separately within said extrusion head. The door module 2 has a structure identical to that of the module in FIGS. 2, 3, 4. It is provided with an elastic part 5 disposed at the periphery of the module on or next to the covering.

The elastic part 5 is linked on a first face to the module 2 and is possibly protected on another face by a film 6. The film 6 has a moisture barrier function, and is made for example of polyethylene.

The manufacture of the elastic part 5 of the seal bead 4 takes place in a manner almost similar to that described above (with reference to the manufacture in the cavity of a mold), except as regards the deposition phase which takes place directly on the surface of one of the first or second elements, without passing through a transfer mold.

Furthermore, the application of the bead 4 on the second element (or on the first element) can take place by pressing the first element (or second element), the gasket bead still having an active upper face for the connection. with said element (first or second), the hardening or setting of the material of the core of the sealing bead can be obtained by keeping the first and second elements pressed against each other.

The invention has been described in the particular case of the manufacture of a door module ready for mounting on a motor vehicle door frame but applies to the production of any other modular element, in particular window modules which can be used in the automotive industry or in building construction (greenhouse, verandas, etc.)

Claims

1- Method for producing in situ a bead of seal between a first element and a second element, characterized in that an element chosen from the first and second elements is provided with a bead of seal sealing (4) of determined shape and section, said of a sealing bead comprising a flexible elastic part (5) obtained by the mixture of a polyol compound and a polyisocyanate compound, the elastic part (5 ) of the sealing bead (4) having on its peripheral surface a hydrophobic skin (5b) forming a sealed envelope.

2- Method according to claim 1, characterized in that the skin (5b) consists of a layer attached to the elastic part (5).

3- A method according to claim 1, characterized in that the skin (5b) came from manufacturing with the elastic part (5).

4- A method according to any one of claims 1 to 3, characterized in that the sealing bead (4) is formed by extrusion of a single-component product.

5- Method according to any one of claims 1 to 3, characterized in that the seal bead (4) is formed by co-extrusion of the elastic part (5) and the skin (5b). -6- A method according to any one of claims 1 to 3, characterized in that the seal bead (4) is formed in an extrusion head (12), by reaction of at least two components supplied separately within said extrusion head.

7- sealing bead (4) obtained by the method according to any one of claims 1 to 6, characterized in that the skin (5b) is based on hydrophobic polyol.

8- sealing bead (4) according to claim 6 characterized in that the hydrophobic polyol comprises hydrocarbon chains such as fatty acids.

9- sealing bead according to one of claims 7 or 8 characterized in that the skin (5b) is formed from a thermoactivable, photoactivable or chemoactivable compound. -Joint cord according to one of claims 6 to 9, characterized in that the elastic part (5) has a relative density of less than 0.5, in particular of the order of 0.1 to 0.4. -Joint cord according to one of claims 7 to 11, characterized in that the sealing bead has a compression force of the order of 0.3 to

2 N per cm, preferably between 0.5 to 1.5 N per cm - Element, such as in particular a door module (2) of a motor vehicle, ready to be secured to a frame or other surface, characterized in that that the element is provided with a gasket bead of defined shape and section, said gasket bead comprising at least one flexible elastic part obtained by the mixture of a compound comprising a polyol hydrophobic and an isocyanate and having a compression force of the order of 0.3 to 2 N per crn, preferably between 0.5 to 1.5 N per cm.