FR3075686A1 - METHOD OF MANUFACTURING A RACKET, AND CORRESPONDING RACKET - Google Patents

Abstract

The present invention relates to a method (100) for manufacturing a racket for a ball game, in particular padel or beach tennis, comprising a frame with a head defining a striking surface of the ball, and a handle mounted in the extension. of the head outside the striking surface of the ball, the method comprising the following steps: a) forming (110) the head, and possibly the handle, the head, and possibly the handle, having an exposed surface comprising a composite material, or a thermoplastic or thermosetting material, and then b) a step of cooking the head, and optionally the handle, is carried out in which, between step a) and step b), applying (120) a silica-based film on at least a portion of the exposed surface of the head, and optionally the handle, the film being configured to be a decorative surface and / or to apply, preferably directly, the decoration of the racket. The present invention also relates to a corresponding decorated racket.

Description

Invention background

The present invention relates to the field of sports articles, and in particular sports accessories. In particular, the present invention relates to a method of manufacturing a racket for a game of balls, in particular padel or beach tennis, which is decorated, and the corresponding decorated racket.

On current rackets, and in particular on padel rackets, the decoration of the frame and / or the sieve is carried out manually, after the step of crosslinking the frame by baking which makes it possible to obtain the general shape of racket. However, before being able to decorate the frame, it is necessary to prepare the surface to be decorated, in order to guarantee good resistance of the decorations, which is conventionally carried out by successive sanding and puttying steps which are also carried out manually. .

Once the surface is properly prepared and ready, a layer of paint and / or decals are applied to it to obtain the desired decorations. Finally, a layer of varnish is applied to the whole to protect the decorations.

However, this decoration process is often tedious, in particular because of the often mediocre quality of the surface to be decorated after baking and because of the manual implementation of the puttying and sanding steps. Thus, it is often necessary to carry out several stages of puttying and sanding before obtaining a surface which can be decorated. Such steps of surface preparation thus increase the manufacturing time of the racket, and therefore its cost, and generally represent more than half of the manufacturing time of the racket. In particular, the addition of putty during the preparation of the surface to be decorated is generally followed by a firing step before the implementation of sanding. In addition, the addition of putty to the racket during the stages of preparation of the surface to be decorated, also results in an increase in the weight of the racket, which is not always distributed uniformly over the entire racket.

Furthermore, the decorated surfaces thus obtained are not always durable, in particular for the sieves of padel rackets or beach tennis. Indeed, the sieve is the part of the racket on which the ball hits, which creates strong localized stresses which can lead to cracks and / or delamination of the paint. In addition, it is also possible to observe cracks and / or detachments of the paint at the level of the frame: in fact, in the event of an impact on the frame, this results in vibrations propagating along the frame. and which could weaken the layer of paint applied to it.

Document FR 3 038 844 describes in particular a padel racket in which the decorations are positioned between a composite layer of the racket and a transparent or translucent protective layer, for example made of PU or ABS. According to the process, the decorations are applied to the frame, as well as the transparent or translucent protective layer, before the baking step. However, such a method does not guarantee that the decorations, and in particular their shape, will be kept after cooking, in the event of deformation of the frame during cooking.

Subject and summary of the invention

The present invention aims to solve the various technical problems stated above. In particular, the present invention aims to provide a method of manufacturing a racket, in particular padel or beach tennis, faster and making it possible to reduce the steps to be implemented, in particular the steps of puttying and sanding. Furthermore, the present invention aims to provide a method of decorating a racket making it possible to obtain a durable and qualitative decoration.

Thus, according to one aspect, a method of manufacturing a racket for a ball game, in particular padel or beach tennis, is proposed, comprising a frame with a head delimiting a hitting surface of the ball, and a handle mounted in the extension of the head outside the striking surface of the ball, the method comprising the following steps: a) forming the head, and optionally the handle, the head, and optionally the handle, having an exposed surface comprising a composite material, or a thermoplastic or thermosetting material, then b) a step of baking the head, and possibly the handle, is carried out in which, between step a) and step b), a film is applied to silica base on at least part of the exposed surface of the head, and possibly of the handle, the film being configured to be a decorative surface and / or to apply, preferably directly, the decoration of the racket.

Thus, the method comprises the application of a silica-based film on the material of the frame of the racket before cooking, making it possible, after cooking, to obtain a surface ready to decorate and no longer requiring multiple sanding steps. and puttying. In particular, during cooking, it appeared that the silica-based film adhered in particular to the material of the frame and more generally to the materials of the racket, and made it possible to have a smooth and solid surface which could be directly decorated after the cooking. The use of such a film then makes it possible to dispense with the long and costly stages of puttying and sanding, by making it possible to directly apply the paint and / or the decoration decals, then the varnish. A process is therefore obtained which is faster to implement, and therefore less costly. In addition, thanks to the absence of putty, we also obtain a lighter and better balanced racket.

Furthermore, the film being based on silica, it is resistant to high temperatures, in particular to the temperatures used for baking the frame, and is easily decoratable after baking, for example by offering a perfectly white surface as a background for the decorations.

Finally, the film has mechanical strength allowing it to have better grip on the head and possibly the handle of the racket, which allows for more durable decorations over time, limiting cracks and flaking. painting, for padel rackets in particular.

Preferably, the head, and possibly the handle, has an exposed surface comprising a composite material, for example made of glass and / or carbon fibers pre-impregnated with a thermosetting resin such as an epoxy resin.

These are the conventional materials used to form the racket frames: these are composite materials which are applied for example to a bladder then cooked under pressure to obtain a rigid and solid frame, while being light. In this embodiment, the silica-based film is applied in particular directly to the composite material before baking, on which it easily adheres, then is baked at the same time as the composite material, thus leading to an exposed surface of the frame formed by the baked film covering the baked composite material. It is then no longer sufficient to decorate the baked film with paint and decals to obtain a decorated racket more quickly.

Alternatively, the head, and possibly the handle, has an exposed surface comprising a thermoplastic or thermosetting material, for example polycarbonate or polyethylene. In this case, these are rackets formed from a core of deformable material surrounded by a layer of rigid coating. The rigid coating layer can then be formed by a thermoplastic or thermosetting material which is arranged around the core before being baked. In this case, the silica-based film is then applied directly to the rigid coating layer before baking, on which it adheres easily, then is baked at the same time as the rigid coating layer, thus leading to an exposed surface of the frame. formed by the baked film covering the baked coating layer. It is then no longer sufficient to decorate the baked film with paint and decals to obtain a decorated racket more quickly.

In particular, the method according to the present invention makes it possible to decorate easily and at a reduced cost the rigid coating layer, after baking, that is to say by eliminating any deformations of the rigid coating layer which may appear during cooking. Indeed, a rigid coating layer in ABS for example can prove to be complicated to decorate, in particular when it has a certain thickness, and can lead to a deformation of the decoration during cooking. Thanks to the method according to the present invention, the decoration by painting and / or decals is carried out in a conventional manner, after cooking, which makes it possible to overcome the structural modifications which may take place during cooking.

It should be noted that the rigid coating layer can also be formed by a composite material, in which case the silica-based film is directly applied to the composite material as described above.

Preferably, the racket head comprises a full screen, for example of deformable material, mounted in the frame of the racket, and the silica-based film is applied to the exposed surface of the racket head, that is to say say on at least part of the exposed surface of the frame and the screen. These are more specifically padel rackets for which the screen can be formed by a material different from that of the frame, and is mounted in the frame.

Preferably, the cooking of the head, and possibly of the handle, is carried out in a mold at a temperature between 150 ° C and 200 ° C and for a time between 15mn and 45mn.

Preferably, the film is microporous, for example comprises microbeads of silica in a polymer matrix, for example made of polyethylene. The choice of a microporous film, obtained in particular thanks to the silica microbeads, makes it possible to facilitate the encrustation of the paint therein, during the application of the decorations on the film, whether before or after cooking. The adhesion of the paint to the film is therefore increased, which limits the flaking phenomenon of the paint, and therefore makes it possible to obtain a more durable decoration over time.

Preferably, the film can comprise between 45% and 70% by mass of silica beads, preferably between 50% and 65% by mass.

The microporous film is therefore a highly loaded monolayer film.

Preferably, the film has a thickness, for example measured according to standard ASTM D374, of between 50pm and 500pm, preferably between 100prn and 300pm, and more preferably between 150pm and 250pm. Such a thickness makes it possible not to modify the mechanical behavior of the sieve of the racket, and to perfectly match the shape of the latter during the application of the film. Indeed, too thin a film can lead to the formation of folds, especially when applying it on the frame which would become difficult to achieve. Conversely, too large a thickness of the film leads to a weight and rigidity incompatible with the application of rackets for ball games. In addition, too thick a film would also lead to the creation of defects at the edges of the frame, where the radii of curvature imposed on the film are high.

Preferably, the film may have a smoothness value according to Sheffield (in English: "Sheffield smoothness"), for example measured according to the Tappi T-538 method, between 10 and 100 Sheffield units, preferably between 10 and 75 Sheffield units.

Preferably, the film is decorated, before step b) of baking, for example by printing on the film.

The film allows decoration, for example by printing, before the cooking step, which further reduces the decoration time of the racket: in fact, the film is directly printed with the desired decoration, then is positioned in particular on the racket frame before cooking. Once the cooking is done, the surface obtained is already smooth and decorated, and it is no longer necessary to carry out other subsequent steps.

Such a mode of implementation is particularly suitable for so-called heartless rackets, that is to say for rackets having no through opening between the handle and the sieve. In this case, the exposed surface of the frame on which the film is applied is relatively simple and not very complex, which makes decoration easier by providing it directly on the film.

Preferably, the manufacturing process is free of step after step b) of cooking.

Preferably, the film is united, preferably white, before step b) of baking. In this case, the decoration is intended to be applied after cooking, the plain film then forming a background not requiring an additional layer of paint. In other words, the film is similar to synthetic paper on which you can easily and correctly make the desired decorations, with the desired rendering.

Preferably, the film can have a whiteness index, or whiteness, measured for example according to standard ASTM E-313, greater than or equal to 60%, preferably greater than or equal to 75%.

Preferably, the method also comprises, after step b) of baking, a step c) of decorating the film, for example by affixing decals on the film and / or of painting, for example of polyurethane paint.

According to this mode of implementation, a layer of paint is then applied, then the decals, in a conventional manner.

Such an implementation mode is particularly suitable for rackets said to have a heart, that is to say for rackets having a through opening between the handle and the sieve. In this case, the exposed surface of the frame on which the film is applied is relatively complex, in particular at the level of the heart where the film can form folds or overlap. The decorations are then applied in the traditional way, after cooking, which facilitates their positioning and improves their rendering.

The paint that can be used on the film after curing can be a polyurethane paint. Indeed, polyurethane paint appeared to be particularly suitable for use on such a film.

Preferably, the film covers the striking surface of the ball. The film is therefore applied mainly where the decorations are most visible and the most fragile for traditional padel or beach tennis rackets.

Preferably, the frame comprises a bladder, and step b) of cooking also comprises pressurizing the bladder. This is a classic mode of implementation for rackets made of composite materials.

Preferably, the head, and possibly the handle, comprises two substantially parallel main surfaces separated by a peripheral edge, and a film is applied to the two main surfaces up to the peripheral edge, and an element is placed on the peripheral edge or on apply decorations to the peripheral edge.

In this embodiment, the film to be decorated is not applied to the entire edge of the racket. On the contrary, the method provides for the application of an added element covering the edge of the racket, and therefore the ends of the films to be decorated. A perfect finish is then obtained at the edges, on which the thicknesses linked to the films to be decorated are hidden by the added element.

Preferably, the process is free from the step of applying putty and / or sanding before applying the decoration on the film.

According to another aspect, a racket for ball games, in particular padel or beach tennis, is also proposed, comprising a frame with a head delimiting a striking surface for the ball, and a handle mounted in the extension of the head to the exterior of the striking surface of the ball, in which the head, and possibly the handle, comprises a composite material, for example made of glass and / or carbon fibers pre-impregnated with a thermosetting resin such as epoxy resin, or comprises a thermoplastic or thermosetting material, for example polycarbonate or polyethylene, covered at least in part by a film based on silica bonded to the material of the head, and possibly of the handle, and decorated or covered with decorations.

Brief description of the drawings The invention and its advantages will be better understood on reading the detailed description of a particular embodiment, taken by way of non-limiting example and illustrated by the appended drawings in which: - Figure 1 is a schematic representation of a padel racket according to the present invention, - Figure 2 is a flowchart of a first mode of implementation of the invention, and - Figure 3 is a flowchart of a second mode of implementation of the invention.

Detailed description of the invention

Figure 1 schematically illustrates a padel racket 1 according to the invention.

Conventionally, the racket 1 comprises a racket head 2 forming a striking surface, and a handle 3.

The handle 3 is mounted in the extension of the racket head 2, and comprises: a handle 4 and two branches 6, 8 connecting defining a hollow space 10, also called heart, allowing the passage of air.

The racket head 2 has two striking surfaces 12, 14 opposite and substantially parallel, and a song connecting peripherally the two striking surfaces 12, 14 and covered by a peripheral strip 18 providing an aesthetic finish to the song of the racket. The two striking surfaces 12, 14 are moreover decorated according to the method described below, and possibly have air passage holes 16.

In particular, the two faces of the frame of the racket 1 are each covered by a silica-based film 20, 22. Each silica-based film 20, 22 has an end edge 20a, 22a which is not visible on FIG. 1 that at the level of the handle 4 and of the hollowed-out space 10, the rest of the end edge being covered elsewhere by the peripheral strip 18.

The silica-based films 20, 22 can be used as a support for the decorations applied to the racket 1, in particular for a layer or more layers of paint and / or one or more decals, as described in more detail in the figure. 2.

Alternatively, the silica-based films 20, 22 can already be decorated, for example by printing, before their application to the frame of the racket 1, as described in more detail in FIG. 3.

According to a variant not shown, the handle 4 can be connected to the racket head 2 by a solid connection zone: in this case, we will then speak of a heartless racket.

FIG. 2 illustrates the various stages of a first mode of implementation of a method 100 for manufacturing a padel racket according to the present invention.

More particularly, the method 100 comprises a first step 110 of forming the frame of the racket with a material to be cooked. Thus, the frame can be formed in a conventional manner, with a frame made of composite material, for example made of glass and / or carbon fibers pre-impregnated with a thermosetting resin such as an epoxy resin. It is in particular possible to use a composite material comprising glass fibers pre-impregnated with a thermosetting resin, and free of carbon fiber. The composite material is placed on a bladder and is intended to be cooked under pressure to form the final frame.

Furthermore, the racket head can be completed with a full screen, formed for example by a deformable material capable of absorbing shocks, for example in foamed material, such as poly (ethylene vinyl acetate) (EVA) , poly (vinyl chloride) (PVC) or polyether urethane (PU), cork, rubber, or latex. Advantageously, the screen is formed in one piece, by molding, cutting or machining the deformable material. The block of deformable material thus obtained is then positioned in the frame, before cooking, to form a racket with a head having a full sieve.

Once the frame has been formed, during a step 120, the silica-based films 20, 22 are applied to at least part of the exposed surface of the frame and the screen, so as to cover it at least in part.

The silica-based film 20, 22 may be a film of the synthetic paper type, comprising for example silica beads in a polymer matrix, for example of polyethylene. The silica beads can for example represent 60% by mass of the film, and confer a microporous structure on the film.

An example of such a film is manufactured by the company PPG, under the name of Teslin®, for example the Teslin® SP800.

Such a film is preferably white, and has a thickness of, for example, between 150 μm and 250 μm.

Once the films 20, 22 have been applied, and in order to harden the frame, the frame and sieve assembly is positioned in a baking mold during a step 130, while the bladder is connected to a pump to be put under pressure. during cooking.

The frame and the sieve are then cooked, for example between 150 ° C and 200 ° C for a time between 15mn and 45mn.

A racket is then obtained with a full sieve, the exposed surface of which is ready to be decorated, and does not require a puttying and / or sanding step. Thus, during a step 140, paint and / or decals are applied to the films 20, 22 of the racket in order to decorate it, and possibly a strip attached to the edge of the frame so as to hide the ends of the films 20 , 22. We then obtain a racket 1 as shown in Figure 1 which will have required less manufacturing time than a standard racket, and whose decorations will be more durable over time than that of a standard racket.

Alternatively, the racket head, and possibly the handle, can be formed by a deformable core material, covered by a rigid coating layer forming a frame. The rigid covering layer can be formed from covering sheets, for example thermoplastic or thermosetting sheets such as thermoformed polycarbonate sheets, or else from sheets of composite material as described above. The polycarbonate sheets in particular have properties of high solidity, making the racket more robust, and can be previously decorated before their application on the core, which facilitates the decoration of the racket. The covering sheets can be placed on the deformable core material by application of a pressure difference (application under vacuum or with an overpressure) allowing to perfectly match the shape and contours of the deformable core material.

In this embodiment, the two faces of the deformable core material are each covered by a coating layer, in order to form the two striking surfaces. Thus, the silica-based films 20, 22 are in this case applied to the exposed surface of the coating layers, then the assembly is baked and finally decorated as described above.

Such a first mode of implementation is advantageously used to manufacture and decorate rackets comprising a heart, such as that illustrated in FIG. 1. Indeed, because of the worked shape of the heart, it is easier to apply the decorations on the racket after cooking, to guarantee their positioning, and also to obtain a correct finish at the edge of the heart.

FIG. 3 illustrates the different stages of a second embodiment of a method 200 for manufacturing a padel racket according to the present invention.

In the second mode of implementation, the first step 210 of forming the frame is identical to that 110 of the first mode of implementation.

On the other hand, in a second step 220, films based on silica are applied which are previously decorated, for example printed. In this case, after the step 230 of baking the frame with the films, the decorations are already finalized, and there is no additional step to be provided, except possibly adding the added element 18 on the peripheral song of the head.

Such a second embodiment is advantageously used to make and decorate heartless rackets. Indeed, the surface to be decorated being mainly flat, the positioning and application of decorated films based on silica can be done more easily and more precisely than on a racket with heart. In addition, there is no additional finish to be expected as is the case at the heart for rackets with heart.

Thus, thanks to the invention, it becomes possible to easily and quickly decorate a racket for a ball game. In particular, the method makes it possible to reduce the duration of implementation of the decoration steps, while making it possible to obtain decorations that are more durable over time.

Claims (11)

1. Method (100, 200) of manufacturing a racket for a ball game, in particular padel or beach tennis, comprising a frame with a head delimiting a hitting surface of the ball, and a handle mounted in the extension of the head outside the hitting surface of the ball, the method comprising the following steps: a) forming the head, and optionally the handle, the head, and optionally the handle, having a surface exposed comprising a composite material, for example glass and / or carbon fibers pre-impregnated with a thermosetting resin such as an epoxy resin, or a thermoplastic or thermosetting material, for example polycarbonate or polyethylene, then b) a baking step (130, 230) is carried out on the head, and optionally on the handle, for example in a mold at a temperature between 150 ° C and 200 ° C and for a period between 15 min and 45 min, characterized in that than, between step a) and step b), a film (20, 22) based on silica is applied (120, 220) to at least part of the exposed surface of the head, and possibly of the handle, film being configured to be a decorative surface or to apply, preferably directly, the decoration of the racket. 2. Method (106, 200) according to claim 1, in which the film is microporous, for example comprises microbeads of silica in a polymer matrix, for example made of polyethylene. 3. Method (100, 200) according to claim 1 or 2, wherein the film (20, 22) has a thickness between 50pm and 500pm, preferably between 100prn and 300pm. 4. Method (200) according to any one of the preceding claims, in which the film (20, 22) is decorated, before step b) of baking, for example by printing on the film. 5. Method (100, 200) according to any one of claims 1 to 3, wherein the film is united, preferably white, before step b) of baking. 6. Method (100) according to the preceding claim, also comprising, after step b) of baking, a step c) of decorating the film (140), for example by affixing decals on the film and / or of painting, for example polyurethane paint. 7. Method (100, 200) according to any one of the preceding claims, in which the film (22, 24) covers the striking surface of the ball. 8. Method (100, 200) according to any one of the preceding claims, in which the frame comprises a bladder, and in which step b) of cooking also comprises pressurizing the bladder. 9. Method (100, 200) according to any one of the preceding claims, in which the head, and optionally the handle, comprises two substantially parallel main surfaces separated by a peripheral edge, and in which a film is applied (22, 24 ) on the two main surfaces up to the peripheral edge, and there is an added element on the peripheral edge or decorations are applied to the peripheral edge. 10. Method (100, 200) according to any one of the preceding claims, free from the step of applying putty and sanding before applying the decoration to the film (22, 24). 11. Racket (1) for ball game, in particular padel or beach tennis, comprising a frame with a head (2) delimiting a striking surface of the ball, and a handle (3) mounted in the extension of the head (2) outside the striking surface of the ball, in which the head, and optionally the handle, comprises a composite material, for example made of glass and / or carbon fibers pre-impregnated with a thermosetting resin such as an epoxy resin, or a thermoplastic or thermosetting material, for example polycarbonate or polyethylene, covered at least in part by a film (22, 24) based on silica bonded to the material of the head, and possibly of the handle , and decorated or covered with decorations.