Wiper blade with dual coating

Abstract

The invention relates to a wiper blade for a windscreen wiper, comprising a body made of an elastomer-based material, the body having a first external surface opposite a second external surface, wherein said first and second external surfaces are at least partly covered with a coating, and wherein the coating on the first external surface is at least partly different from the coating on the second external surface and / or wherein at least one of said first and second external surfaces has been subjected to a treatment while the at least one other first or second external surface has undergone an at least partly different treatment. Method for producing the wiper blade.

Description

Dual-coating wiper blade

[0001] The invention relates to windshield wiper blades having a coating on their external surfaces with improved properties, as well as their preparation method

[0002] Motor vehicles are commonly equipped with windshield wiper systems to wash and / or wipe the windshield and prevent the driver's view of their surroundings from being obstructed. The wiper blades in such a system are typically driven by arms that move back and forth. These blades rub against the outer surface of the glass, such as the windshield, and remove water, carrying it out of the driver's field of vision. In a conventional design, the wiper blades are made of articulated arms that hold the blade at several points. In a more recent design called "flat blade," the wipers are made of a semi-rigid assembly that supports the blade along its entire length.

[0003] Generally, a wiping blade is made of an elastically deformable material based on an elastomer, supplemented with additives, notably to improve its mechanical properties, elasticity, wear resistance, resistance to external aggressions, or to facilitate the manufacturing process. These additives may include, for example, reinforcing fillers, plasticizers, vulcanizing agents, and agents that protect against UV radiation, oxidation, ozone, and / or wear.

[0004] In the case of wiper blades for automotive windshields, these blades must have characteristics that allow for effective wiping of the windshield they move across while also providing a quiet environment for the vehicle's occupants, meaning they must avoid generating sound waves or noise. However, during windshield wiper use, the constant friction of the blade against the windshield causes premature wear, resulting not only in reduced wiping performance but also in noise.

[0005] It is known to coat wiping blades with a coating composition to improve their properties. These coating compositions can, in particular, improve resistance to wear and / or abrasion, enhance wiping performance, and adapt the blades to the weather environment (ice, dust, high temperatures, for example).

[0006] To increase its durability, meaning to ensure effective wiping over the long term, it is known to coat a wiper blade with a relatively hard coating, or one containing hard fillers (which do not alter the overall rigidity of the coating). To limit noise when the wiper blade is moved across the windshield, especially when it is only slightly wet, it is known to add lubricating fillers to the coating to reduce the coefficient of friction. Another issue is preventing delamination of this coating during use.

[0007] However, it is sometimes desirable to have a coating with several of these properties. However, adding different components to a coating composition to achieve these properties can lead to an overall loss of effectiveness if the compatibility between the elements is not verified and if one property inhibits another. In other words, introducing these properties into a composition does not result in an additive effect.

[0008] Furthermore, it may be desirable to have a windshield wiper blade that can be used in different conditions, for example in winter and summer weather.

[0009] Patent EP 3078554 proposed using three stacked coating layers to achieve good hardness and sliding properties on the windshield.

[0010] FR2969078 describes a windshield wiper blade whose coating has increased cross-linking on part of the external surface.

[0011] However, there is still a need for wiping blades that combine certain properties with a simple process for preparing them.

[0012] Within the framework of the present invention, it has been demonstrated that it is possible to obtain wiping blades whose coating combines several properties that are generally difficult to reconcile in the same coating.

[0013] Therefore, the present invention relates to a windshield wiper blade comprising a body made of an elastomer-based material, the body having a first external surface opposed to a second external surface, characterized in that said first and second external surfaces are covered at least in part with a coating and in that the coating of the first external surface is at least in part different from the coating of the second external surface and / or in that at least one of said first and second external surfaces has been subjected to a treatment, the other at least of said first or second external surfaces having not undergone any treatment or having undergone at least a different treatment.

[0014] In particular, the present invention relates to a windshield wiper blade comprising a body made of an elastomer-based material, the body having a first external surface opposed to a second external surface, characterized in that said first and second external surfaces are covered at least in part with a coating and in that the coating of the first external surface is at least in part different from the coating of the second external surface and / or in that at least one of said first and second external surfaces has been subjected to a treatment, at least the other of said first or second external surfaces having undergone at least in part a different treatment.

[0015] The invention also relates to a method for preparing a windshield wiper blade, comprising the steps of

[0016] a) Prepare a body made of elastomer-based material comprising a first external surface opposite a second external surface,

[0017] b) deposit a first coating on at least part of a first external surface of the body made of elastomer-based material,

[0018] c) deposit a second coating on at least part of a second external surface of the body made of elastomeric-based material,

[0019] the composition and / or thickness of the first coating being at least partly different from the composition and / or thickness of the second coating,

[0020] d) recover the body made of elastomer-based material, the first and second external surfaces of which are at least partially covered with a coating.

[0021] According to one variant, the process for preparing wiping blades includes the steps of

[0022] a) prepare a body made of elastomer-based material comprising a first external surface opposite a second external surface,

[0023] b) treat at least a part of at least one of said external surfaces by a technique chosen from ion bombardment, halogenation or plasma,

[0024] c) deposit a first coating on at least part of a first external surface of the body made of elastomer-based material,

[0025] d) deposit a second coating on at least part of a second external surface of the body made of elastomeric-based material,

[0026] By "material based on", we mean a material comprising at least 10% elastomer(s), preferably at least 20%, more preferably at least 35%.

[0027] The term "elastomer(s)" refers to a polymer exhibiting "hyperelastic" properties, obtained after cross-linking the polymer. These elastomers include natural or synthetic elastomers, alone or in mixtures, particularly those selected from the group consisting of natural rubbers (NR), polychloroprenes (CR), ethylene propylene diene monomers (EPDM), nitrile rubbers (NBR, HNBR, XNBR), polybutadienes (BR), butyl rubbers, epichlorohydrins (ECO / GECO), ethylene acrylate copolymers (VAMAC type), polyurethanes (PU), fluorinated elastomers, and silicone elastomers (VMQ / FMQ). These elastomers can be used alone or in mixtures. Examples include NR / EPDM, NR / CR, EPDM / PP, and other mixtures known to those skilled in the art.

[0028] Preferably, the elastomers are chosen from the group consisting of NR, EPDM, CR and mixtures based on these elastomers.

[0029] Indeed, the material comprises at least one basic elastomer, synthetic or natural, as well as various fillers and / or additives, notably to improve its mechanical properties, elasticity, wear resistance, resistance to external aggressions, or to facilitate the manufacturing process. These may include, for example, reinforcing fillers, plasticizers, vulcanizing agents, and agents that protect against UV radiation, oxidation, ozone, and / or wear.

[0030] Advantageously, the composition of the coating on the first external surface is at least partly different from the composition of the coating on the second external surface.

[0031] Conventionally, the wiping blade 1 of a wiper blade according to the invention has an elongated shape and is designed to be supported by a body of the wiper blade (not shown). The blade 1 comprises a lip 3 and a heel 5 which are connected by a hinge 7. The assembly of lip 3, heel 5, and hinge 7 forms a basic body of the blade 1.

[0032] The heel 5 allows the blade 1 to be hooked into the body of the wiper. The lip 3 is designed to come into contact with the outer surface of a window such as a windshield for wiping.

[0033] The hinge 7 is formed by a thin strip of material which gives the blade a certain flexibility and allows it to tilt when changing the direction of movement of the brush, in other words a front-to-back tilting movement of the lip.

[0034] Advantageously, at least a portion of the blade 1 is coated with a coating composition, in particular the basic body of the blade is coated with this composition. Embodiments can thus be envisaged in which, for example:

[0035] - only lip 3 is coated with the composition,

[0036] - the entire blade 1 is coated with the composition.

[0037] The lip of the wiping blade has two main opposite faces designated by A and B in what follows, and a narrower face opposite the heel (3a).

[0038] The first surface (A) can thus be covered with a first coating, and the second surface (B) is covered with a second coating, the composition of the first coating being at least partly different from the composition of the second coating.

[0039] The surface at the end opposite the hinge may be left uncoated to allow for proper windshield wiping. In one variation, it may be at least partially covered with the first or second coating; optionally, it may be covered with a third coating, for example, graphite.

[0040] According to one variant of the invention, the thickness of the coating on the first external surface of the body made of elastomer-based material is at least partly different from the thickness of the coating on the second external surface.

[0041] The difference in thickness can be related to the amount of coating compound applied per unit area of ​​the elastomer-based material body; it can also be related to the addition of one or more layers to the first external surface compared to the second external surface. Specifically, the coating of the first external surface may consist of one or more layers, and the coating of the second external surface may have a different number of layers than the first external surface. The coating layers may consist of a wiper blade coating and / or a graphite deposit on top, to improve the blade's glide.

[0042] This embodiment can be carried out alone. It can also be carried out in combination with the embodiment in which the composition of the coating of the first external surface is at least partly different from the composition of the coating of the second external surface.

[0043] According to one embodiment of the invention, the first and second external surfaces of the elastomer-based body have been subjected to a surface treatment, identical or different for each surface. This embodiment can be carried out alone, or in combination with at least one of the other embodiments presented in the description.

[0044] The treatment of one of the first and second external surfaces of the elastomeric-based body may be carried out before applying a coating to the elastomeric-based body. This coating may be identical on the first and second external surfaces of the elastomeric-based body.

[0045] In one embodiment, the treatment is performed on a body made of an elastomer-based material in which the coating of the first external surface is at least partially different from the coating of the second external surface. The difference may lie in the composition and / or thickness of the respective coatings of said first and second external surfaces, as indicated above.

[0046] Advantageously, the coating of at least one of said first and second external surfaces is in the form of a dry film containing at least one resin (or binder) and fillers, the fillers being chosen from reinforcing fillers, abrasive fillers and lubricating fillers.

[0047] It is also advantageous that the coating of one of the said first and second external surfaces is in the form of a dry film containing at least one resin (or binder) and fillers, the fillers being chosen from among reinforcing fillers, abrasive fillers and lubricating fillers and that the coating of the other of the said first and second external surfaces is in the form of a dry film containing at least one resin (or binder) and / or fillers, the fillers being chosen from among reinforcing fillers, abrasive fillers and lubricating fillers.

[0048] Advantageously, the filler / binder ratio of the coating of one of said first and second external surfaces is different from the filler / binder ratio of the coating of the surface opposite it.

[0049] Advantageously, the coating, more advantageously of the said first and second external surfaces, is in the form of a dry film containing at least one resin (or binder) and fillers, the fillers being chosen from among reinforcing fillers, abrasive fillers and lubricating fillers.

[0050] The respective compositions of the coating of the first and of the coating of the second external surface of the body in elastomer-based material may, for example, contain at least one different charge and / or at least one different concentration of at least one charge contained in said composition.

[0051] According to one embodiment of the invention, the filler-to-binder ratio of the coating on one of said first and second external surfaces is different from the filler-to-binder ratio of the coating on the opposite surface. This embodiment can be implemented alone or in combination with the preceding ones.

[0052] Advantageously, the wiper blade of the present invention comprises a body made of an elastomer-based material, the body having a first external surface opposed to a second external surface, the blade being characterized in that

[0053] said first and second external surfaces are covered at least in part with a coating, and in that the coating of the first external surface is at least in part different from the coating of the second external surface, and / or in that at least one of said first and second external surfaces has been subjected to a treatment, the other at least one of said first or second external surfaces having undergone a treatment that is at least in part different; and in that

[0054] the coating, more advantageously of said first and second external surfaces, is in the form of a dry film containing at least one resin (or binder) and fillers, the fillers being chosen from reinforcing fillers, abrasive fillers and lubricating fillers, where the filler / binder ratio of the coating of one of said first and second external surfaces is different from the filler / binder ratio of the coating of the surface opposite it.

[0055] The resins (or polymeric binders) used have particle diameters ranging from 0.01 to 1 micron. The particles can be solid or have a core-shell structure.

[0056] Among the various polymeric binders, we find polyurethanes, polyacrylates, polycarbonates, polyimides, silicones, nitriles, polyacrylonitril, epoxies, polyamides, polyamines, polyolefins, vinyls, styrenics, polyesters, aminoplasts, phenoplasts, polyacetals, chlorinated or fluorinated polymers (PVC, PTFE, PVF, for example), polyetheretherketone (PEEK) or their mixtures, as well as their derivatives. Binders can be derived from synthetic components or bio-based elements.

[0057] Advantageously, the resin may be, in particular, an aqueous-phase resin comprising at least one aqueous-phase polymer of the acrylic, vinyl, styrenic, or urethane type. The polymer may be a homopolymer or a copolymer. These polymers may be used alone or in mixtures depending on their compatibility or the desired final properties. Advantageously, the resin contains at least one acrylic polymer.

[0058] Fillers include reinforcing, abrasive, and functional fillers. These fillers can be minerals in general, such as silica (in all its forms: colloidal, pyrogenated, powdered, etc.), alumina, zirconium oxide, as well as fibers (carbon, wood, metallic, polymer, or mixtures thereof), glass (powder, beads, fiber), graphene, carbonates (calcium, magnesium, etc.), nitrates, organic beads (silicone, polyethylene, polycarbonate, polyurethane, polyacrylate, etc.), and / or cellulose and its derivatives. Fillers can be microscopic or nanoscopic in size and in various chemical forms.

[0059] Advantageously, the coating composition contains lubricating fillers, which are solid lubricating agents.

[0060] The solid lubricant can be chosen from lubricants known to those skilled in the art. These include natural lubricants such as graphite and molybdenum disulfide, as well as synthetic lubricants such as graphite fluoride, tungsten disulfide, boron nitride, tungsten, molybdenum niobium biselenide, titanium iodide and titanium disulfide, and mixtures thereof in all proportions. In particular, at least one solid lubricant is chosen from graphite, boron nitride, molybdenum disulfide, polytetrafluoroethylene (PTFE), and clays, and mixtures thereof in all proportions. The solid lubricant is generally in the form of particles, preferably with an average diameter of 1 to 20 µm, advantageously 2 to 8 µm.

[0061] The composition of the coating of the aforementioned first and second external surfaces of the body, made of elastomeric material, may further include one or more additives. The additive may be selected from among thickening agents, spreading agents, dispersing agents, and UV-protective agents.

[0062] UV protective agents include UV stabilizing agents and UV inhibiting agents.

[0063] Thickeners are preferably chosen from modified celluloses, modified urethane polymers and different types of stearates (magnesium, sodium, zinc, calcium for example).

[0064] The spreading agent reduces the surface energy of the composition. It can be chosen from silicone surfactants, such as modified dimethylsiloxane polyethers.

[0065] Dispersing agents are designed to ensure better dispersion of particles, such as solid lubricant particles. The dispersing agent is typically a water-soluble polymeric agent; preferably, the polymeric dispersing agent comprises an ionic form of the polymer or copolymer used as the resin. For example, a polyacrylate is preferred when the resin is a polyacrylic resin.

[0066] The composition of each coating, in the form of an aqueous dispersion, can, for example, be applied directly to the wiping blade or to a profiled rubber strip, which is then cut into two or three parts to obtain the wiping blade. The coating composition is applied by spraying it onto the wiping blade or profiled rubber strip, or by coating the wiping blade or profiled rubber strip with the composition; it can also be applied with a brush or by curtain application. The wiping blade or profiled rubber strip is then dried. In the case of the rubber strip, it is finally cut into two or three parts to obtain the wiping blades.

[0067] The application stage may be preceded by a preheating stage and a coating baking stage; the coating baking stage may be carried out in particular in an infrared oven or a convection oven.

[0068] More specifically, a first coating composition made of elastomer-based material can be applied to a first surface (A) of the body. This application can be carried out by spraying, using a curtain technique, or with a brush.

[0069] The elastomeric body is then inverted, and a second coating composition is applied to a second surface (B) of the elastomeric body, opposite the first surface. Application can be carried out by spraying, curtain application, or brushing. The second composition is at least partially different from the first composition and / or the thickness of the second composition on the second face is at least partially different from the thickness of the first composition on the first face; the difference in thickness is related, in particular, to the amount of coating composition applied per unit area of ​​the elastomeric body.

[0070] The application of the first and second coatings respectively must avoid any overlap between said coatings.

[0071] The production system has two separate systems to prevent the two coatings from mixing. Therefore, the containers holding the coatings, the tubes, the spray gun (in the case of spray application), and the curtain must be kept separate.

[0072] Optionally, a drying or baking step is carried out between application to the first surface and application to the second surface.

[0073] A drying or baking step is carried out after the application of the coating compositions to the said first external surface and second external surface of the body in elastomer-based material.

[0074] According to one embodiment of the invention, the coating on the first external surface is an ice-resistant coating that offers advantageous properties in winter weather due to its high hydrophobicity; such coatings are described, for example, in FR2925507. The coating on the second external surface is a high-performance coating for the other three seasons, notably due to its low friction, but it is not ice-resistant. A wiper blade equipped with such a wiping blade will ensure good wiping quality at all times and will withstand various weather conditions.

[0075] The high-performance winter coating, due to its resistance to ice, should be positioned on the windshield side when the wiper is stopped, on cars that allow it.

[0076] According to other embodiments of wiping blades according to the invention, which may be taken together or separately

[0077] - A primary abrasive surface "scrapes" impurities from the windshield. This function can be achieved through surface nanostructure on the elastomer-based matrix or via abrasive inorganic fillers with a hardness greater than that of glass, such as alumina or silica, contained in the coating of the primary surface; the coating of the secondary outer surface does not contain any abrasive filler. The polymer matrix, additives, and other mineral and organic fillers may be the same or different.

[0078] The coating of a first surface (A) contains organic or inorganic fillers; the coating of the second surface (B) is either unfilled or contains different fillers than surface A. The fillers can be reinforcing, abrasive, or functional. Such fillers can include minerals in general, such as silica (in all its forms: colloidal, pyrogenated, powdered, etc.), alumina, zirconium oxide, but also fibers (carbon, wood, metallic, polymer, or mixtures thereof), glass (powder, beads, fiber), graphene, carbonates (calcium, magnesium, etc.), nitrates, organic beads (silicone, polyethylene, polycarbonate, polyurethane, polyacrylate, etc.), and / or cellulose and its derivatives. The fillers can be microscopic or nanoscopic in size and in various chemical forms.

[0079] - A first surface allows for the application of a hydrophobic coating to the windshield, and the coating on the second surface can be either hydrophobic or hydrophilic without depositing on the glass. The hydrophobic or hydrophilic component can originate from a hydrophobic or hydrophilic polymer matrix, a hydrophobic or hydrophilic filler (organic or inorganic), or hydrophobic or hydrophilic additives.

[0080] - One surface has a hydrophobic coating and the second surface has a hydrophilic coating. The hydrophobic or hydrophilic part can come from a hydrophobic or hydrophilic polymer matrix or from a hydrophobic or hydrophilic filler (organic or inorganic) or from hydrophobic or hydrophilic additives.

[0081] - The respective coatings of the first external surface and the second external surface give them different coefficients of friction.

[0082] - The respective coatings of the first external surface and the second external surface contain lubricating fillers with different lubricating particle sizes, thus providing different slipperiness and / or different chemical natures.

[0083] - The respective coatings of the first external surface and the second external surface have different properties, such as better adhesion, better abrasion resistance, better frost resistance, better UV resistance, better slip resistance, different rigidity. Brief description of the figures

[0084] Figure 1 is a schematic cross-sectional view of a wiper blade of a windshield wiper according to the invention. The blade 1 is obtained by a conventional manufacturing process known to those skilled in the art.

[0085] Example

[0086] The study is based on two coatings with different powder-to-binder ratios (P / L ratio). Coating A has a ratio greater than 1.5, and coating B has a ratio less than 1.5. Coating A was applied to face A, and coating B to face B. The slide with both coatings is referred to as "slide A / B." Having a different P / L ratio can, for example, allow for a higher lubricant content and thus reduce friction.

[0087] Reference A Reference B Styrene acrylic resin 2024.5 Graphite (lubricating filler) 5534.1 Polymethylsilsesquioxane particles - 3.3 Additive(s) 0.51.3 Solvent(s) 24.536.8

[0088] Depending on whether the wiper blade is moving upwards or downwards, lower friction helps reduce chatter and system instabilities that can lead to engine seizures. Blade A / B was compared to a reference blade to confirm the feasibility of applying two different coatings to the same blade. The reference blade has coating A on both sides.

[0089] Laboratory tests and functional tests were carried out and are summarized in the following table.

[0090] Reference Blade A / B Adhesion Test Compliant: rating 1 Compliant: rating 1 Average Wiping Qualities 7.0 / 10 7.2 / 10 Dry Abrasion Compliant Compliant

[0091] Dry abrasion test: wear resistance performance is measured by a dry abrasion test with different coating compositions.

[0092] Coated blades are positioned to slide across a smooth glass surface subjected to a compressive load (here 15 N / m) for a given number of cycles (here 43,200 cycles). After this number of cycles, the rubber deposit on the glass and the blade wear are assessed.

[0093] Adhesion test: the adhesion of different coating formulations to rubber is evaluated. The adhesion test consists of making back-and-forth movements on the coated wiper blade using a paper soaked in alcohol-based windshield washer fluid, then observing and rating the surface of the coating using an internal grid from 1 to 5, with rating 1 corresponding to no change (Rating 2-3: slight delamination; Rating 4-5: Coating detachment).

[0094] The wiping quality is assessed under real-world conditions, i.e., on a vehicle windshield. A rating scale from 1 to 10, with 10 being the best, allows the blade to be categorized according to the presence of defects such as streaks, persistent or absent haze, and noise.

[0095] The A / B blade complies with the tests and wipes similarly to the reference.

Claims

Wiper blade comprising a body made of an elastomer-based material, the body having a first external surface opposed to a second external surface, characterized in that said first and second external surfaces are covered at least in part with a coating and in that the coating of the first external surface is at least in part different from the coating of the second external surface and / or in that at least one of said first and second external surfaces has been subjected to a treatment, at least the other of said first or second external surfaces having undergone at least in part a different treatment. Wiper blade according to claim 1, characterized in that the composition of the coating of the first external surface is at least partly different from the composition of the coating of the second external surface. Wiper blade of windshield wiper according to any one of claims 1 or 2, characterized in that the thickness of the coating of the first external surface is at least partly different from the thickness of the coating of the second external surface. Wiper blade according to any one of claims 1 to 3, characterized in that one of said first and second external surfaces has been subjected to a surface treatment and in that the other of said first and second external surfaces has not been subjected to a surface treatment. Wiper blade of windshield wiper according to any one of claims 1 to 4, characterized in that the surface treatment is carried out before the application of the coating on said first and second external surfaces. Wiper blade according to any one of claims 1 to 5, characterized in that the coating of at least one of said first and second external surfaces is in the form of a dry film containing at least one resin (or binder) and fillers, the fillers being chosen from reinforcing fillers, abrasive fillers and lubricating fillers. Wiper blade according to claim 6, characterized in that the coating of said first and second external surfaces is in the form of a dry film containing at least one resin (or binder) and fillers, the fillers being chosen from reinforcing fillers, abrasive fillers and lubricating fillers. Wiper blade according to claim 6 or 7, characterized in that the filler / binder ratio of the coating of one of said first surface and second external surface is different from the filler / binder ratio of the coating of the surface opposite it. Wiper blade according to any one of claims 6 to 8, characterized in that the charges present in the coating of one of said first and second external surfaces are at least partly different from the charges present in the coating of the first or second external surface opposite it. Wiper blade according to any one of claims 6 to 9, characterized in that the coating of one of said first external surface and second external surface comprises hydrophobic fillers, and in that the coating of the first or second surface opposite it does not contain hydrophobic filler and / or contains hydrophilic fillers. A method for preparing a windshield wiper blade according to any one of the preceding claims, characterized in that it comprises the steps of a) Preparing a body made of elastomeric material having a first external surface opposite a second external surface, b) depositing a first coating on at least a part of a first external surface of the body made of elastomeric material, c) depositing a second coating on at least a part of a second external surface of the body made of elastomeric material, the composition and / or thickness of the first coating being at least partly different from the composition and / or thickness of the second coating, d) recovering the body made of elastomeric material, the first and second external surfaces of which are at least partly covered with a coating.

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