Flocking patch material in automobile industries, comprises a support on which a flocking fibers are deposited by an adhesive, where the support is formed from a flexible thermoplastic elastomer and a flexible adhesive

Part of flocked material, in particular for motor vehicles, and method for its manufacture

The invention relates to a part made of flocked material of the type comprising a support on which flocking fibers are bonded by means of an adhesive.

Various types of parts made of flocked material are already known, which comprise a support on which are bonded flocking fibers usually formed of natural, artificial or synthetic textile fibers of selected length. These fibers are bonded to the support by means of an adhesive while being oriented under the action of an electric field. This produces pieces that can have different appearances, for example velor, carpet, plush, suede, etc. The flocking process itself can be carried out on a wide variety of supports, for example plastic, paper, metal, etc.

The invention is more particularly, but not limited to, parts made of flocked material intended for the field of the automotive industry.

In this particular field, window cleaners or storage compartments are known in particular, window cleaners being parts used in doors and against which the windows slide during their upward or downward movement. These parts are usually formed from a flexible material made either of vulcanized rubber covered with a black flock, or of a thermoplastic rubber to which dark fibers are applied by bonding and surface treatment techniques. These parts can also be stiffened using a rigid core made of metal or plastic.

The parts thus obtained are generally rigid and most often dark in color, which limits their possibilities of application.

The object of the invention is in particular to overcome the aforementioned drawbacks.

Its main objective is to produce a part made of flocked material which differs from known parts by its highly flexible character.

The invention also aims to provide such a part made of flocked material which can be obtained with the most varied shapes, designs, decorations, colors depending on the desired applications.

It also aims to provide such a piece of flocked material which may have a translucent character allowing the transmission of light or be produced with light shades, for example pastel.

It is yet another object of the invention to provide such a part made of flocked material which has a soft appearance to the touch and offers retention and non-slip properties for objects capable of being placed on the part thus obtained. .

Yet another object of the invention is to provide a part made of flocked material which can be obtained afterwards by injection molding or else by cutting.

The invention provides for this purpose a part made of flocked material of the type defined above, in which the support is formed from a flexible thermoplastic elastomer of chosen composition, and in which the adhesive is a flexible adhesive chosen so as not to alter the flexibility of the support.

This flexible thermoplastic elastomer therefore differs from materials of the rubber type of the prior art, in particular by its properties of great flexibility.

The combination of such a flexible support with a flexible adhesive makes it possible to obtain a part which durably retains its flexibility properties, without the latter being able to be altered by 1 / adhesive.

For this purpose, the thermoplastic elastomer should be chosen. This is advantageously chosen from the elastomers of the Styrene Ethylene Butadiene Styrene (SEBS), Styrene Ethylene Butadiene Styrene / Polypropylene (SEBS / PP), Styrene Butadiene Styrene / Polypropylene (SBS / PP), Ethylene Propylene Diene Monomer / Polypropylene (EPDM) families / PP), more or less crosslinked, among the elastomers of the Polyurethane (PU) families, Thermoplastic Elastomers (TPE) and Partially Vulcanized Thermoplastic Rubbers (TPV) and also among combinations of the above elastomers with traditional plastic materials. These include in particular Polystyrene (PS), ABS (Acryl Butadiene Styrene), Polycarbonates (PC), Polypropylene (PP) and Polyethylene (PE), this list not being exhaustive.

These elastomers can be produced by mixing different components comprising base polymers, as well as different additives such as oils or plasticizers, mineral or organic fillers, protective agents, crosslinking agents, processing agents, etc.

In the invention, it will be necessary to ensure that these additives do not exude so as not to leave a fatty layer on the surface of the part after processing.

The support itself may be opaque, but the invention most particularly contemplates translucent supports or light-colored supports allowing transmission of light through the part thus produced. To allow such translucency, the thermoplastic elastomer should contain additives in a minimum amount, in particular as regards the fillers added to the base polymer.

The support can be produced by various techniques known per se, for example by transformation in mono, bi or tri-material mode, in single or expanded mode, by extrusion or calendering for cutting. The parts can also come from an overmolding operation on plastic, metal or any other compatible supports. The thermoplastic elastomer is preferably obtained by injecting hot material into a cold mold.

The choice of the adhesive is also decisive given that it must not only be flexible and keep its flexibility, but not alter the flexibility of the support, that is to say not be aggressive towards the support. .

Adhesives having high elongations at break are particularly contemplated, such as those selected from water-based adhesives in flexible polymerizable resin, or water-based adhesives with co-solvent, and water-based organic adhesives based on rubber polymer. synthetic optionally containing other adjuvants or cosolvents (for example glycols or vinyl or cellulosic adjuvants). More particularly, dispersions of polyurethane or of catalyzed acrylic resins or mixtures of the two will be used. It should be noted that such adhesives can also contain isocyanates.

The adhesive is generally applied by a technique known per se, for example by spraying with a gun, application by roller, brush or paintbrush, etc. Most often, a prior surface treatment of the support is necessary to allow good adhesion of the adhesive.

This surface treatment, if necessary, must be chosen so as not to alter the flexibility of the support. Generally, it is preferred to apply a bonding primer, that is to say a composition usually formed from one or more solvents. But plasma or corona type treatment techniques can also provide the expected results.

It is possible, by way of example, to use an adhesion primer chosen from solvents or mixtures of solvents which may contain resins (natural or synthetic) or else synthetic polymers of low molecular weight.

The flock fibers are those currently used and available commercially. They may be so-called long or very short fibers. Although the invention is not limited to a particular length of fibers, fibers of a length between 0.1 and 1 mm are however preferred in order to allow the part to be given a velvet-like appearance.

They may be fibers commonly used in flocking techniques, such as for example polyamide, polyester, viscose, cotton, etc.

As already indicated, the fibers can optionally be colored or printed to give them a particular coloring.

The flock fibers are bonded to the support by means of the adhesive on one face of the support which may have a chosen texture. The expression chosen texture is understood to mean that the face of the part is either smooth or provided with particular reliefs. It may in particular be a face having a grained appearance.

This texture is preferably imparted to the support before application of the adhesive and bonding of the fibers. It is possible, as a variant, to produce the texture after flocking, or else to perform a combination of such operations.

The support itself is advantageously obtained by injection or cutting.

The part made of flocked material of the invention has excellent mechanical strength. In particular, the flocking fibers withstand repeated cycles of twisting of at least 180 'on the part, without compromising the strength of the adhesive and of the fibers.

In another aspect, the invention relates to a method of manufacturing a part made of flocked material, as defined above, which comprises the following operations:

a) forming a support in a flexible thermoplastic elastomer of selected composition, by molding or cutting;

b) applying to one face of the support a flexible adhesive chosen so as not to alter the flexibility of the support;

c) applying flock fibers to the face of the support coated with adhesive, the fibers being oriented by an electric field; and

d) fix the adhesive and clean the fibers.

Operation b) advantageously comprises:

bl) the application of a layer of a bonding primer on the face of the support; and b2) applying a layer of the flexible adhesive to the layer of the bonding primer.

Operation c) is carried out by flocking techniques, known per se, using known equipment which allows the implantation of the fibers in the adhesive with a chosen orientation, generally perpendicular to the surface of the support. .

The fixing of the adhesive from operation d) consists in setting the adhesive, for example by polymerization or crosslinking, to ensure the maintenance of the flocking fibers on the support.

In the following description, given only by way of example, reference is made to the accompanying drawings, in which:

- Figure 1 is a perspective view of a part made of flocked material according to the invention;

- Figure 2 shows detail II of Figure 1; and

- Figure 3 is a sectional view on an enlarged scale of part of the part schematically showing the various components that constitute it.

FIG. 1 shows a part made of flocked material intended in the example for the automotive industry and which may in particular constitute a part of a dashboard or of a console, a door panel, etc. It is therefore a part of aspect

Figure 1 shows part 10 in its entirety, while figure 2 shows a detail of this part and figure 3 shows a sectional part, on an enlarged scale, of part 10.

As can be seen in FIG. 3, part 10 comprises a support 12 made of a flexible thermoplastic elastomer of chosen composition which has an exposed or upper face 14. In the example, the support is translucent and it has a thickness E of between 0.05 and 50 mm. The face 14 has a chosen structure. It can be smooth or grained or have another form of relief. Here, the face 14 comprises raised parts 16 in the form of elongated rods directed in two perpendicular directions (see also FIG. 2).

The support 12 is produced by injection or cutting according to techniques known per se.

On the face 14 is applied a layer of an adhesive 18, namely a flexible adhesive chosen so as not to alter the flexibility of the support. This adhesive is applied by techniques known per se, for example by spraying, application by roller, brush or paintbrush, etc.

Preferably, the application of the adhesive is carried out after surface treatment, typically after application of a bonding primer which facilitates the holding of the adhesive, without however affecting the flexibility of the support. However, other treatment techniques, for example of the plasma or corona type, can be envisaged.

To the adhesive are applied flock fibers 20 which are oriented by means of an electric field to form a selected angle with the surface, generally an angle of 90 °. The application of the fibers is carried out by techniques known per se by means of a known installation.

Generally, the length of the flock fibers is between 0.1 and 1 mm. These fibers can be chosen from natural, artificial or synthetic fibers.

The method therefore mainly comprises the following operations: application of the adhesive, implantation of the fibers under the action of an electric field, fixing of the adhesive (by polymerization or crosslinking), removal of the non-bonded fibers (generally by suction ) and possibly finishing. The latter operation can include, for example, a surface treatment, color printing, etc.

After manufacturing the part from flocked material, it is desirable to check its properties, in particular its hardness (for example Shore hardness) and the resistance of the flock (flocked fibers) by using known tests or tests specially designed for this effect.

It has been observed that the flock withstands repeated cycles of torsion carried out on a part made of flocked material according to the invention. In fact, when such a part is subjected to repeated twists at an angle of at least 180 ′, the flock remains integral with the support without the adhesive, and therefore the flocked fibers, separating from the support. This excellent mechanical strength comes from both the choice of the support and the choice of the adhesive, both of which retain their flexibility, while remaining mutually linked.

It should be noted that the application of the flocking fibers can be pneumatic or electro-pneumatic.

An embodiment of the invention will now be described.

EXAMPLE

A part of flocked material is produced in the form of a dashboard mat or a motor vehicle dashboard by injection of a material of the Styrene Ethylene Butadiene Styrene (SEBS) type having a hardness of 70 Shore A and exhibiting a grained honeycomb surface. On this surface is deposited a layer of a bonding primer, then a layer of a flexible adhesive formed here of a mixture of polyurethane (PU) dispersion and acrylic resin in the presence of an isocyanate. Pink fibers are then applied by a flocking process. The adhesive is fixed by crosslinking and the part is then cleaned.

The part obtained possesses and retains great flexibility and a soft feel, which makes it particularly suitable for constituting an appearance part for a motor vehicle.

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The invention finds a particular application in the field of the automotive industry, for example to form a component of a dashboard, a console, a door panel or any other part in the passenger compartment.

It makes it possible to produce flexible parts, which may optionally be translucent or have a light tint, and thus allow light to pass through, which may be advantageous when driving at night to view certain parts of the vehicle.

Depending on the nature and length of the flocking fibers, the piece can be given a soft feel of the velvet, suede, plush, fur, etc. type. This touch can be combined with a particular texture of the part such as, for example, a grained appearance.

The parts of the invention also have the advantage of having advantageous properties of thermal and sound insulation.

As already indicated, the fibers can optionally be produced with different colors or even undergo printing to produce particular decorations, pictograms, etc.

The invention also finds applications in fields other than the automobile industry, such as furniture, household appliances, decoration.