FR2654643A1 - METHOD FOR MANUFACTURING A GLUE SKI, AND SKI STRUCTURE OBTAINED BY THIS METHOD. - Google Patents

Abstract

The process for producing a ski with a composite structure according to the invention comprises a stage of assembling at least a first (1) and a second (2) element by the action of a layer of adhesive (5). A film (6) in the solid state is interposed between the said layer of adhesive (5) and the junction surface (3) of the said first element (1), the said film comprising at least one layer based on polymers, such as a grafted polyethylene, permitting the adhesion of the adhesive (5) on the assembly formed by the element (1) and the film (6).

Description

The present invention relates to the manufacture of the skis used

  in winter sports, and intended to slide on snow and ice.

  Current skis generally have a composite structure in which different materials are combined so that each of them intervenes optimally, taking into account the distribution of mechanical stresses. Thus, the structure generally comprises peripheral protective elements, forming the upper face. and the side faces of the ski, internal resistance elements or resistance blades, made of a material having a high resistance and a high stiffness The structure also comprises filling elements such as a core in honeycomb structure, and a sole of slip forming the underside of the ski and ensuring good

sliding on snow.

  To obtain the appropriate physical characteristics, the manufacture of modern skis therefore uses very diverse materials: the gliding soles are generally made of polyethylene; the alveolar cores are made of wood or synthetic foam; the edges arranged on the lower edges of the ski are made of steel; reinforcements are often provided in aluminum alloy; the upper surfaces of the

  skis are made of thermoplastic sheet.

  The composite nature of such a ski structure leads to skiing by assembling several elements previously coated or impregnated with an adhesive. Naturally, the adhesive must be

  compatible with all the elements to be assembled.

  In the classic manufacture of a ski, the two binders

  mainly used are epoxies and polyurethanes.

  These binders are not sufficient to easily adhere all the materials which one wishes to use in the composition of a modern ski. To obtain adhesion on certain materials, one must have recourse to surface treatments or coatings of primers,

to promote adhesions.

  Primary coatings have many disadvantages.

  In particular, the primers are initially in solution in solvents: the solvents react on the substrates to which the primer is applied, causing risks of embrittlement; in addition, during their evaporation, they are aggressive towards users, they risk causing accidents, and cause harmful pollution. The application of primers must also be

  done with great regularity, to obtain a thick layer

  constant, which leads to complex and difficult operations. The primer, once applied to a substrate, requires using the substrate relatively quickly for the manufacture of the ski, excluding a

long-term storage.

  Surface treatments entail costly operations

  his, painful manipulations and significant investments.

  The object of the present invention is in particular to avoid the drawbacks of known methods, by proposing a new method and a manufacturing and a new ski structure allowing bonding on practically all surfaces of the components of the ski, without

  require surface treatments or primers.

  In particular, the invention allows the bonding of a polyamide sheet.

  as an upper ski surface, by gluing with an adhesive

  epoxy, polyester glue, or vinyl ester glue.

  To achieve these and other objects, the method of manufacturing a ski according to the present invention comprises a step of assembling at least two elements by the action of a layer of adhesive between the joining surfaces of the two elements. ; according to the invention, there is interposed between the adhesive layer and the junction surface of at least one of the elements a film in the solid state comprising at least one layer based on grafted polymer or copolymer giving the film properties of compatibility with glue The film will be called by the

  continued in the text "compatibilizing" film.

  According to one embodiment, the film is advantageously based on a polymer or copolymer grafted by the action of carboxylic acid,

  carboxylic acid anhydride or carboxylic acid ester.

  A polymer can usefully be grafted by the action of acrylic acid, methacrylic acid, or maleic anhydride, or by a

  combination of two or three of these products.

  The grafted polymer can be a polyethylene.

  Alternatively, the grafted polymer can be a copolymer

  ethylene and vinyl acetate (EVA).

  According to one embodiment, after grafting with an acid, it can be neutralized with metal ions of the sodium, zinc or other type.

  to obtain an ionomer-based film.

  According to the invention, it is possible in particular to use an epoxy adhesive or a polyester adhesive to assemble by bonding, with the interposition of such a film based on grafted polyethylene, a first element consisting of one of the following materials: polyamide, non-polyethylene

  treated, polyethylene terephthalate, polybutadiene terephthalate, polypro-

  pylene, aluminum alloy, treated aluminum or steel.

  Other objects, features and advantages of this

  The invention will emerge from the following description of embodiments.

  tion particular, made in connection with the accompanying figures, among which: Figures 1 to 4 illustrate a bonding method according to a first embodiment of the invention; Figures 5 and 6 illustrate a method of assembly by gluing according to a second embodiment of the invention; and FIG. 7 illustrates a method of assembly by gluing according to a

  third embodiment of the invention.

  In the embodiment shown in Figures 1 to 4, the method of the invention allows the assembly of a first element 1 and a second element 2, according to their respective joining surfaces 3 and 4, by means of 'a layer of glue 5 interposed between said junction surfaces 3 and 4 The second element 2 is assumed to be compatible with the glue 5, that is to say that the glue 5 has good adhesion on the second element 2 On the other hand , the first element 1 is made of a material which may not have good compatibility with the adhesive, that is to say that the adhesive 5 does not have good adhesion

  on the junction surface 3 of the first element 1.

  To allow the assembly of the first element 1 with the second element 2, the first element 1 not having a good adhesion power with the adhesive 5, one interposes between the layer of adhesive 5 and the junction surface 3 of the first element 1 a film 6 known as "compatibilizer" comprising at least one layer based on grafted polymer or copolymer giving film 6 compatibility properties with the adhesive 5 Le

film 6 is hot melt.

  The film 6 must have a bonding face, or face oriented towards the adhesive 5, in a material such that the adhesive 5 has good adhesive power on the film 6. The film must also comprise an assembly face, or oriented face. towards the junction surface 3 of the first element 1, in a material allowing it to be joined to said

  junction surface 3 of the first element 1.

  As regards the connection of film 6 to the first element 1, the connection between the film 6 and the first element 1 can be ensured by a chemical or physico-chemical bond or by interdiffusion of the

  polymer chains, or by mechanical anchoring, or by welding.

  As regards the presence of the adhesive 5, a first possibility, represented in FIGS. 1 to 4, consists in coating the joining surface 4 of the second element 2 with an adhesive 5, as shown in FIG. 3, before assembly by pressing the adhesive layer 5 against the film 6 and obtaining the assembly shown in the

figure 4.

  A second way of ensuring the joining between the film and the second element 2 can be provided in the case where the second element 2 comprises a junction surface 4 based on polyester resin not entirely crosslinked. It is then possible to apply the junction surface 4. of the second element 2 directly against the film 6, and, by heating, the not entirely crosslinked resin of the second element 2 itself ensures the bonding function, the adhesion being obtained by complementing

crosslinking of said resin.

  In the case of a metallic reinforcement, the film 6 can advantageously

  This must be done by an electrostatic powdering process.

  In all cases, a very thin film 6 can be used, of thickness advantageously between a few microns and a few

  tenths of a millimeter: a thickness of a few microns may be sufficient.

  One can advantageously use a film 6 based on polymer or copolymer grafted by the action of carboxylic acid or carboxylic acid anhydride, for example by acrylic acid, by acid

  methacrylic, or by maleic anhydride.

  Such a film 6 can in particular be made of grafted polyethylene, for example of polyethylene grafted with maleic anhydride. This embodiment makes it possible, for example, to ensure the bonding by an epoxy adhesive or a polyester adhesive of a first element 1 the joint surface of which is made of one of the following materials:

  polyamide, untreated polyethylene, polyethylene terephthalate, polybuta-

  diene terephthalate, polypropylene, treated aluminum, aluminum alloy

or steel.

  The film 6 can consist of a copolymer of ethylene and vinyl acetate (EVA), grafted by the action of carboxylic acid or carboxylic acid anhydride. According to another embodiment, after grafting with an acid, neutralization is carried out with metal ions of sodium, zinc or other type to obtain a film based on an ionomer. Such an ionomer film can advantageously be used for bonding with an epoxy adhesive or a polyester adhesive of a first element 1, the joining surface of which is made of one of the following materials: untreated polyethylene,

  aluminum alloy, treated aluminum or steel.

  For example, the use of a compatibilizing film 6 of polyethylene grafted with maleic anhydride allows the bonding of a first element 1 of polyamide by an adhesive 5 of epoxy resin. According to the invention, the adhesion of the film 6 on the first element 1 by chemical reaction between the maleic anhydride groups grafted to

  the surface of the polyethylene and the end groups of the polyamide.

  These groups exist in low concentration in the material, but have the particularity of migrating to the extreme surface during the extrusion of the polyamide sheet and are therefore available for the reaction. The reaction leads to the substitution of the atom. oxygen of the maleic cycle by the nitrogen atom of the amine end group of the polyamide and formation of a water molecule It is necessary to bring the substrates to temperatures above 115 C to trigger the reaction We can therefore hot plate , by calendering or pressing, the film 6 against the first element 1 to ensure their joining together

to the other.

  * Film 6 can be of the monolayer type, as shown

Figures 1 to 4.

  Alternatively, the film 6 can be of the multilayer type, as shown in FIG. 7, comprising at least a first layer 61 forming an adhesive face compatible with the adhesive 5, and a second layer 62 forming an assembly face compatible with the first element 1. In the embodiment shown in FIGS. 1 to 4, the assembly is carried out in successive stages: during a first stage illustrated in FIGS. 1 and 2, the film is assembled by calendering or hot pressing 6 says "compatibilizer" on the junction surface 3 of the first element 1 having a lack of adhesion with the adhesive 5; the temperature should be raised to the softening point of the film; during a second step, the adhesive 5 is applied to the junction surface 4 of the second element 2, as shown in Figure 3; during a third step, the layers formed by the adhesive 5 and the film are applied against each other

  6, performing the assembly as shown in FIG. 4.

  In the embodiment shown in FIGS. 5 and 6, all the elements are placed in a mold, that is to say, in order: the first element 1, the film 6, the layer of adhesive 5, the second element 2; by hot pressing, all the elements are applied one on the other, and the assembly is carried out in one step The temperature of

  the assembly must also be raised to the softening point

of the film.

  It will be understood that the method of the invention makes it possible to obtain a ski with a composite structure, comprising at least a first element 1 and a second element 2 secured to one another by an adhesive 5 placed between the two joining surfaces elements, a so-called "compatibilizing" film being placed between the adhesive and the first element 1, said film allowing the elements to be joined by bonding to one another. In such a ski structure, the presence of 'a so-called "compatibilizing" film of polymer comprising at least

  minus one layer consisting of grafted polymers or copolymers.

  The present invention is not limited to the embodiments.

  which have been explicitly described, but it includes the various

  variants and generalizations contained in the field of claims

the following;

Claims (13)

  1 Method for manufacturing a ski with a composite structure, comprising a step of assembling at least a first element (1) and a second element (2) by the action of a layer of adhesive (5) between the joining surfaces (3, 4) of the two elements, characterized in that a film (6) is interposed between the adhesive layer (5) and the joining surface (3) of the first element (1) solid comprising at least one layer based on grafted polymer or copolymer giving the film (6) compatibility properties with the glue (5).   2 Method according to claim 1, characterized in that the film (6) is based on polymer or copolymer grafted by the action of carboxylic acid, carboxylic acid anhydride or carboxylic acid ester. 3 Method according to claim 2, characterized in that the film is based on polymer or copolymer grafted by the action of acrylic acid. 4 Method according to claim 2, characterized in that the film is based on polymer or copolymer grafted by the action of acid methacrylic.   Method according to claim 2, characterized in that the film is based on polymer or copolymer grafted by the action of maleic anhydride.   6 Method according to claim 2, characterized in that the film is based on polymer or copolymer grafted by a combination   acrylic acid and / or methacrylic acid and / or maleic anhydride than.   7 Method according to any one of claims 2 to 6,   characterized in that the polymer is a polyethylene.   8 Method according to any one of claims 2 to 6,   characterized in that the polymer is a copolymer of ethylene and vinyl acetate (EVA).   9 Method according to claim 7, characterized in that, after grafting with an acid, neutralized with a metal ion to   obtain an ionomer-based film.   Method according to claim 7, characterized in that the adhesive (5) is an epoxy adhesive or a polyester adhesive, the first element (1) has a joining surface (3) made of one of the following materials: polyamide, polyethylene untreated, polyethylene terephthalate, polybutadiene terephthalate, polypropylene,   aluminum alloy, treated aluminum or steel.   11 Method according to claim 9, characterized in that the adhesive (5) is an epoxy adhesive or a polyester adhesive, the first element (1) has a joining surface (3) made of one of the following materials: non-polyethylene treated, alloy   aluminum, treated aluminum or steel.   12 Method according to any one of claims 1 to 11,   characterized in that the film (6) is of the monolayer type.   13 Method according to any one of claims 1 to 11,   characterized in that the film (6) is of the multilayer type, comprising at least a first layer (61) forming an adhesive face compatible with the adhesive (5), and a second layer (62) forming an assembly face   compatible with the first element (1).   14 Ski with composite structure, comprising at least a first (1) and a second (2) elements secured to one another by an adhesive (5) disposed between the junction surfaces (3, 4) of said elements (1 , 2), characterized in that a film (6) of grafted polymer or copolymer is disposed between the adhesive (5) and the first element (1), said film allowing the elements (1, 2) to be joined together by gluing 'one by compared to each other.   15 Ski according to claim 14, characterized in that the   film (6) of grafted polymer or copolymer is made of grafted polyethylene.   16 Ski according to claim 14, characterized in that the film (6) is based on a copolymer of ethylene and vinyl acetate (EVA).   17 Ski according to claim 14, characterized in that the film (6) is based on ionomer.