EP0811401A1 - Complex covering for snowboards - Google Patents

Abstract

Complex for covering (1) mechanical structure of ski plate comprises at least one primary protective plastic layer (10) which makes up the external face of the ski which contains a secondary fabric layer of dry crosscut fibres (11). Secondary layer is stuck to primary layer and tertiary layer (12) which provides mechanical barrier between secondary layer and reinforcing resin of mechanical structure. Also claimed is plate coated with claimed complex.

Description

The present invention relates to a covering complex intended to complete the mechanical reinforcement structure of a gliding board. It relates more particularly to articles in the form of laminates comprising different composite materials such as skis in general, snowboards, monoskis and other similar objects.

In most cases, a gliding board is made up of a mechanical assembly grouping together the essential elements to resist the various stresses in bending, torsion and lateral deformations undergone by the board. These elements are generally reinforcing elements made of composite or metallic materials and filling elements serving as a core to keep the reinforcing elements at a distance.

In order to protect this set from external aggressions and to make the product more attractive, the upper surface and the edges of the board are covered with a protective and decorative top generally consisting of one or more layers of plastic material, decorated or not. However, the role of this upper sub-assembly is limited to protection against scratching, edge blows, UV, cleaning solvents, etc .; but it does not bring any particular improvement in the behavior of the ski.

The object of the present invention is to propose an improvement in the production of a top of a gliding board which has, in addition to its usual role, a damping role, by participating in the attenuation of the vibrations which disturb the driving of the board.

In particular, one of the advantages of the invention is to improve the vibratory behavior of the board by predominantly torsional damping. Most add-on or integrated damping devices especially dampen the energy of the flexural deformations of the board; which is not enough to keep a powerful, precise and regular contact on snow. Thus, it has been found that the damping must be greater in torsion than in pure bending to obtain better contact of the ends of the board on snow. The invention makes it possible to obtain a torsion / bending damping ratio greater than traditional gliding board structures.

For this, the invention relates to a covering complex of a mechanical structure of a gliding board which comprises at least a first protective plastic layer intended to constitute the external face of the gliding board, and a second fabric layer. dry cross fibers; said second layer being bonded to said first protective plastic layer and finally a third barrier layer connected to the second layer by bonding and intended to constitute a mechanical barrier between said second layer and the resin reinforcements of said mechanical structure.

Surprisingly, it has been possible to demonstrate that the second layer of fiber fabric was able to dissipate energy by the friction caused by the fibers crossed between them, during deformations of the board; especially in torsion. The fiber is protected from the outside by the first plastic layer which covers it. On the other side, the third layer constitutes a sealing barrier which allows the woven fiber of the second layer to remain dry at the time of the final assembly of the complex with the rest of the structure of the board, and in particular upon contact with the thermofluidable resin of the structural reinforcement elements.

In addition to its cushioning role, the fiber fabric layer contributes to the exterior decorative rendering of the complex.

According to another characteristic of the invention, the third layer is formed by at least one nonwoven textile web whose face, intended to be connected to the mechanical structure of the board, is impregnated with a low-viscosity hot-melt polymer and low melting point. The polymer in the molten state fills the interstices of the nonwoven layer and makes the assembly waterproof to the thermofluable resin of the reinforcements. The non-woven layer has the advantage of clearly improving the bonding value between the complex and the rest of the structure. gliding board.

According to an additional characteristic, the complex comprises a hot-melt adhesive film between the first protective plastic layer and the second layer of dry fiber fabric and another hot-melt adhesive film between said second layer and the third barrier layer. The presence of the films allows the bonding between the layers and thus offers a wider choice of materials forming the respective layers.

• la figure 1 montre une vue en coupe du complexe selon l'invention avant assemblage avec le reste de la structure de la planche,
• la figure 2 montre une vue écorchée de dessus du complexe en mettant en évidence les différentes couches le constituant,
• les figures 3 à 5 montrent un mode de réalisation du complexe selon l'invention,
• la figure 6 montre une planche de glisse recouvert d'un complexe selon l'invention,
• la figure 7 est une vue en coupe selon A-A de la figure 6,
• la figure 8 est une variante de la planche de glisse de la figure 6.

Other objects, characteristics and advantages of the invention will emerge from the following description of the particular modes, made in relation to the attached figures, among which:

• FIG. 1 shows a sectional view of the complex according to the invention before assembly with the rest of the structure of the board,
• FIG. 2 shows a cutaway view from above of the complex, highlighting the different layers making it up,
• FIGS. 3 to 5 show an embodiment of the complex according to the invention,
• FIG. 6 shows a sliding board covered with a complex according to the invention,
• FIG. 7 is a sectional view along AA of FIG. 6,
• FIG. 8 is a variant of the gliding board of FIG. 6.

Figures 1 and 2 show a complex 1 according to the invention intended to be attached to a mechanical structure 2 of a gliding board.

In this example, the complex 1 is represented in the form of a strip composed of a plurality of layers joined together.

On the external side (EXT) is placed the first protective layer 10 intended to constitute the external face of the complex. This layer is made of plastic and preferably of thermoplastic material.

Preferably, it is a transparent sheet of thermoplastic material chosen from the group consisting of polyamides, polycarbonates, ABS, polyethylene terephthalates (PET), polystyrenes. The diaper can wear a decorative pattern, for example a pattern produced by means of sublimated inks 100 through the external surface of the layer 10.

This first layer must have a sufficient thickness to protect the rest of the complex and absorb the heat diffusion of the inks in depth. It must be greater than or equal to 0.3 mm; preferably of the order of 0.7 mm. Other decorating techniques can be used to replace sublimation. Examples include the use of screen printing, pad printing, hot stamping, etc.

Of course, it is conceivable that the complex comprises several protective layers. In this case, the layers can be assembled together beforehand by coextrusion or by any other means.

According to the invention, the second layer 11 of the complex is a dry fiber fabric. The fabric is preferably a textile of weft and warp thread crossed with crossing angles of 90 degrees or less than 90 degrees (multidirectional fabrics).

The fabric contains no impregnation resin, at least at the core, so as to promote friction between the wires or strands.

The thickness of this second layer can be between 0.2 and 0.7 mm. The grammage of the fabric can be between 200 and 1000 g.m -2.

This second layer may consist of a fabric of synthetic fibers chosen from glass, carbon, para-aramid, polyester or a mixture of these fibers.

The third layer 12 is a barrier layer, the role of which is both to promote the bonding of the complex to the reinforcing structure and to prevent the impregnation of the second layer by the thermofluidable resin of the reinforcing layer 20 during final assembly.

This layer 12 is therefore preferably formed by a nonwoven textile web 120 whose face intended to be connected to the mechanical structure of the board is impregnated with a hot-melt polymer 121 with low viscosity and low melting point. The polymer can fill the interstices of the nonwoven web and make it waterproof to the resin reinforcements.

Among the polymers capable of being suitable, it will be preferred to choose them from ionomers; in particular, those with an MFI (Melt Flow Index) value less than or equal to 7 and a melting point less than or equal to 110 degrees Celcius. The nonwoven textile web also has the advantage of being folded and stretched easily and without breaking.

The nonwoven textile layer associated with the impregnation polymer also constitutes an opaque background revealing the decoration of the complex.

To achieve the cohesion of the complex, a hot-melt adhesive film 130 is interposed between the first protective plastic layer 10 and the second layer 11 of dry fiber fabric and another hot-melt adhesive film 131 between said second layer 11 and the third layer barrier 12.

The bonding films 130, 131 are preferably based on polymer or copolymer grafted by the action of carboxylic acid, anhydrous carboxylic acid or ester of carboxylic acid.

The film can advantageously be made of grafted polyethylene, and more precisely, of polyethylene grafted with maleic anhydride.

Thanks to the choice of the nonwoven textile web and by associating with it a hot-melt film of the type of that designated, we obtain bonding values much higher than those which can be obtained with any other substrate, such as a plastic layer for example. .

The bonding resistance at the interface between the second layer 11 and the reinforcement structure 20 is of the order of 20 N in the presence of the nonwoven layer 120. The resistance is only 4 N without the layer nonwoven, however retaining the sole presence of films 131 and 121 (and zero resistance after aging in an aqueous medium).

The bonding resistance at the interface between the second layer 11 and the first plastic layer 10 is of the order of approximately 12 N with the presence of the bonding film 130.

In addition to its role as a barrier layer, the third layer 12 prevents the chemical modification of the bonding film 131 by the resin of the reinforcements when the film is in particular an ionomer which can react with the epoxides.

Figures 3 to 5 illustrate, by way of example, a method of manufacturing the complex 1 described above. According to FIG. 3, a decoration is firstly printed by hot transfer of sublimable dyes contained in a sheet of support paper 3. The sheet is applied in contact with the surface of the plastic layer 10 and , in a manner known per se, heat and pressure are applied to obtain the diffusion of the dyes through the layer 10. The operating conditions of the decoration cycle are for example 165 ° C. for 2 min at 2 bars.

The next step is to stack the complex; respectively, of the first plastic layer 10 thus decorated, of the bonding film 130, of the second fabric layer 11, then of the other bonding film 131, of the third layer formed of the nonwoven textile web 120 and of the hot melt polymer film 121.

A press cycle is then applied by applying a pressure of the order of 2 to 4 bars and at a temperature of 150 to 165 degrees for approximately 1 to 2 minutes.

A variant consists in carrying out the pre-assembly of part of the complex by hot calendering. For example, the subassembly formed by the film 130, the second layer 11, the film 131, the third layer 12 can be calendered hot at first, then assembled to the plastic layer by pressing in a second step.

The complex thus formed is thus ready for use for the final assembly with the rest of the structure of the gliding board which in particular comprises the reinforcement elements in prepregs.

The final assembly is an operation which consists in molding the structure to the desired shape while obtaining the adhesion of all the constituents between them. The operation is done in a mold of a shape suitable for the desired final shape which is heated to a temperature sufficient to obtain the cooking of the elements. reinforcement in prepregs.

During baking in the mold, the resin of the prepreg reinforcements reaches a temperature of the order of 150 ° C. and becomes fluid. Due to the pressure exerted in the mold, of the order of 7-10 bars, the resin tends to creep in the spaces and interstices left free. This creep is stopped in the direction of the complex thanks to the barrier layer 12. The resins most often used for prepregs in the field of manufacturing skis and snowboards are thermosetting resins of the epoxy type.

The invention also relates to the gliding board provided with a complex as described above. In the case of FIGS. 6 and 7, the gliding board is provided over its entire length with the complex 1 which covers the mechanical structure 2.

This structure 2 comprises an upper reinforcement element or layer 20, a central core 21, a lower reinforcement element or layer 22, lateral metal edges 230, 231 and a sliding sole 24, generally made of polyethylene. The elements 20, 22 are advantageously based on reinforcing fibers and on epoxy thermosetting resin.

The core is made of a material of low density but resistant to compression such as foam, wood or honeycomb.

According to the invention, the complex is assembled on the structure 2 so that the third layer 12 constituting the mechanical barrier is connected by bonding in contact with the reinforcing layer 20 based on fibers impregnated with a hot-meltable resin belonging to mechanical structure 2.

In the example of FIG. 6, the fibers or threads of the fabric layer occupying the entire length of the board are oriented and crossed substantially in a direction inclined at + and - 45 degrees relative to the longitudinal direction II 'of the board.

Damping measurement tests have shown that the ratio between the first torsion and the third flexion in the corresponding frequency range, of the order of 200 Hertz, is greater for gliding boards using the complex of the invention only for boards of traditional structure. We measure that this ratio is in any case greater than 1 and of the order of 1.05 for a ski with a box structure with all-fiber reinforcements and of the order of 1.42 for a ski with a fiber-box structure. metal. For a traditional structure, the ratio is of the order of 0.75 for a ski of the type with any fiber reinforcement and of the order of 0.70 for a ski with fibro-metal reinforcement. We note that these skis which have a ratio greater than 1 have a behavior on snow that can be described as softer thanks to better contact surface glide / snow.

In the example of FIG. 8, the gliding board shown is a ski which has a central portion 30 corresponding to the area for mounting the bindings, a front area 31 extending between the front limit of the central portion 30 and the tip and a rear zone 32 extending between the rear limit of the central portion 30 and the ski heel.

In this case, provision is made for the second layer of dry fibers 11 to be present only in the front region 31 and the rear region 32 to provide predominantly torsional damping in these regions which are particularly stressed and more than the central portion. In the central portion, the layer 11 can be replaced by an additional plastic layer of the same thickness in the complex for example. Alternatively, layer 11 may also not be replaced by an additional layer.

Of course, the invention is not limited to the embodiments thus described and includes all the technical equivalents which may fall within the scope of the claims which follow.

Claims (11)

Covering complex (1) of a mechanical structure (2) of a gliding board comprising at least a first protective plastic layer (10) intended to constitute the external face of the gliding board, characterized in that it comprises a second layer of crossed dry fiber fabric (11); said second layer being bonded to said first protective plastic layer (10) and a third barrier layer (12) connected to the second layer (11) by bonding and intended to constitute a mechanical barrier between said second layer (11) and the resin of the reinforcements of said mechanical structure. Covering complex according to claim 1, characterized in that the third layer (12) is formed by at least one nonwoven textile web (120) whose face intended to be connected to the mechanical structure of the board is impregnated with a hot melt polymer (121) with low viscosity and low melting point. Covering complex according to claim 2, characterized in that the hot-melt polymer (121) is chosen from ionomers. Covering complex according to claim 1, 2 or 3, characterized in that it comprises a hot-melt adhesive film (130) between the first protective plastic layer (10) and the second layer of dry fiber fabric (11) and another hot-melt adhesive film (131) between said second layer (11) and the third barrier layer (12). Covering complex according to claim 4, characterized in that the bonding films (130, 131) are based on polymer or copolymer grafted by the action of carboxylic acid, carboxylic acid anhydride or acid ester carboxylic. Covering complex according to any one of the preceding claims, characterized in that the first layer (10) is a transparent sheet of thermoplastic material chosen from the group consisting of: polyamides, polycarbonates, ABS, polystyrenes, polyethylene terephthalates (PET). Covering complex according to any one of the preceding claims, characterized in that the second layer (11) consists of a fabric of synthetic fibers chosen from glass, carbon, para-aramid, polyester or a mixture of these fibers. Gliding board comprising a mechanical reinforcement structure (2) based on hot-melt resin, characterized in that it is provided over at least part of its length with a covering complex (1) according to any one previous claims; the third layer (12) constituting the mechanical barrier being connected by bonding in contact with a reinforcing layer (20) based on fibers impregnated with a hot-meltable resin belonging to the mechanical structure (2). Gliding board according to claim 8, characterized in that the fibers of the second layer (10) are oriented and crossed substantially in a direction inclined at + and - 45 degrees relative to the longitudinal direction of the board. Gliding board according to claim 9, characterized in that the second layer of dry fiber fabric (11) is present in the complex over only part of the length of the board. Gliding board according to claim 10, characterized in that the second layer of dry fiber (11) is present in the front zone (31) and the rear zone (32) outside the central portion (30) corresponding to the zone mounting fixings.

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