Protective, anti-corrosion and adhesion-promoting element for bare protection or coating application

Abstract

The present invention relates to a protective, anti-corrosion and adhesion-promoting element for bare protection or the application of a coating comprising at least a first layer of a ferrous, non-ferrous, composite, glass or polymer metallic material, characterized in that the element further comprises at least a second layer formed by flame burning, based on a silica compound comprising one or more silicon-oxygen group(s), carried by a carrier gas of the oxygen or dioxygen type (O2).

Description

Title of the invention: Protective, anti-corrosion and adhesion-promoting element for bare protection or application of a coating

[0001] The present invention relates to a protective, anti-corrosion, and adhesion-promoting element for bare protection or the application of a coating comprising a layer based on a silica compound, as well as to a method for manufacturing said protective, anti-corrosion, and adhesion-promoting element.

[0002] It typically applies, but not exclusively, to the fields of aluminum painting in the automotive industry, such as roof bars on a vehicle.

[0003] Roof bars on a vehicle are used to allow the transport of items on the roof. This roof bar may have anti-corrosion properties, thanks in particular to an anodizing treatment and the application of a three-layer primer, base coat and varnish applied to the outer face of the roof bar.

[0004] However, chemical surface treatments such as anodizing use chemical compounds such as chromium VI which are prohibited from use because of the very significant risks of cancer without a threshold effect in humans.

[0005] The object of the present invention is to overcome the disadvantages of prior art techniques by proposing a protective, anti-corrosion and adhesion-promoting element for bare protection or the application of a coating while guaranteeing REACH standards.

[0006] The present invention relates to a protective, anti-corrosion and adhesion-promoting element for bare protection or the application of a coating comprising at least a first layer of a ferrous, non-ferrous, composite, glass or polymer material, characterized in that the element further comprises at least a second layer based on a silica compound comprising one or more silicon-oxygen group(s).

[0007] Thanks to the invention, the element ensures excellent anti-corrosion properties due to its function as a barrier against oxygen and moisture, as well as excellent adhesion-promoting properties, while avoiding the use of elements prohibited by REACH regulations. Furthermore, the element of the invention is easy to manufacture and ensures homogeneous properties across the entire surface treated by the second layer.

[0008] The second layer The element of the invention comprises at least a first layer of ferrous, non-ferrous, composite, glass or polymer material, and furthermore one or more second layer(s) based on a silica compound, said silica compound comprising one or more silicon-oxygen (Si-O) group(s).

[0009] In the present invention, the term "based on" layer means a layer comprising said silica compound.

[0010] Furthermore, a "silicon-oxygen" group means a group consisting of a silicon atom covalently bonded to an oxygen atom (Si-O).

[0011] The second layer of the invention may comprise at least 50% by weight of said silica compound, preferably at least 60% by weight of said silica compound, and particularly preferably at least 80% by weight of said silica compound, relative to the total weight of the second layer. In a particular embodiment, the second layer may comprise only one or more silica compound(s) according to the invention.

[0012] In the present invention, the second layer can be deposited directly onto the surface of the first layer. As such, the second layer is in direct physical contact with the first layer.

[0013] According to another embodiment, the second layer can be deposited indirectly on the surface of the first layer. In this respect, one or more additional layers can be intercalated between the first and second layers. Thus, the second layer is not in direct physical contact with the first layer.

[0014] The second layer can be a layer comprising different types of siliceous compounds.

[0015] According to a first variant, the second layer can be a silicate layer or an organosilicate layer.

[0016] The silicate or organosilicate layer can be obtained from a silane compound.

[0017] Said silane compound may be selected from a hydrocarbon silane, a fluorosilane, a silicate, an organosilicate, and a mixture thereof.

[0018] As a preferred example: - hydrocarbon silane can be tetramethysilane (TMS); - fluorosilane can be triethoxyfluorosilane (TEOF); - silicate is the compound SiO4; - the organosilicate can be chosen from tetraethoxysilane (TEOS), tetramethoxylsilane (TMOS), and one of their mixtures;

[0019] According to a second variant, the second layer can be a polysiloxane layer.

[0020] The polysiloxane layer can be obtained from a siloxane monomer or a silazane monomer.

[0021] As a preferred example: - the siloxane monomer can be chosen from hexamethyldisiloxane (HMDSO), tetramethyldisiloxane (TMDSO), octamethylcyclotetrasiloxane (OMCTSO), and one of their mixtures; - the silazane monomer can be hexamethyldisilazane (HMDSN).

[0022] In a particular embodiment, the second layer may comprise one or more layer(s), each of these layers being obtainable independently according to the first variant or according to the second variant.

[0023] The second layer according to the invention can have a thickness of at most 150 nm, and preferably a thickness ranging from 20 to 50 nm.

[0024] In a particularly preferred embodiment, the second layer can be a hydrophilic layer.

[0025] In the present invention, "hydrophilic" means a material or layer whose surface has a contact angle (or drop angle) strictly less than 80°, and preferably greater than or equal to 0°.

[0026] The contact angle measurement reflects the ability of a liquid to spread on a surface by wettability. The method consists of measuring the angle of the tangent of the profile of a drop deposited on the material or layer, with the surface of the material or layer.

[0027] This contact angle is typically measured using a goniometer, at 25°C, using distilled water.

[0028] The first layer The element of the invention comprises one or more first layer(s) made of a ferrous, non-ferrous, composite, glass or polymer material.

[0029] The first layer may comprise at least 50% by weight of material, preferably at least 60% by weight of material, and particularly preferably at least 80% by weight of material, relative to the total weight of the first layer.

[0030] In a particular embodiment, the first layer may comprise only said material.

[0031] The manufacturing process of the element Another object of the invention is a method for manufacturing the element.

[0032] The element of the invention is easy to manufacture and guarantees homogeneous properties over the entire surface treated by the second layer.

[0033] According to the embodiment specific to the invention, the second layer will be formed by flame treatment.

[0034] The flame treatment process consists of exposing the surface to be treated to a flame.

[0035] The flame of this process is typically a flame formed by the mixture of at least one fuel and at least one oxidizer (i.e. fuel / oxidizer mixture), this type of technique being well known to those skilled in the art.

[0036] The flame is conventionally formed at the outlet or end of a burner (i.e., the outlet orifice), also called the combustion zone, the flame being fed by the fuel / oxidizer mixture. The distance between the burner outlet and the surface to be treated can be at least 2 cm.

[0037] The burner can typically include a first supply for the fuel, and a second supply for the oxidizer.

[0038] In the present invention, the oxidant is preferably in the form of a gas at ambient temperature (25°C), and particularly preferably in the form of a gas at 10°C. It can be, for example, dioxygen or oxygen (O2).

[0039] The oxidizer can come from pure dioxygen or from a mixture of dioxygen with at least one other gas.

[0040] The fuel of the invention is preferably in the form of a gas at ambient temperature (25°C), and particularly preferably in the form of a gas at 10°C. It can, for example, be chosen from among the alkanes.

[0041] By way of example, the fuel can be chosen from methane, propane, butane, and a mixture thereof. The preferred gas is propane.

[0042] The fuel can come from a pure gas or a mixture of several gases. It can come from natural gas.

[0043] During combustion, the flame can reach 1800°C.

[0044] More particularly, flame treatment is used in the present invention as a Sionization process.

[0045] The flame of this process can advantageously be mixed with at least one silane compound as described in the present invention. In other words, the flame comprises a reaction precursor of the silane compound type.

[0046] By way of example, the concentration of the silane compound in the flame can be at most 0.15 mL / min per 100 L / min of fuel / oxidizer mixture.

[0047] The silane compound burns and transforms into silicate (SiOx) which is deposited on the surface to be treated in the form of a thin layer, which can be a few nanometers thick.

[0048] Operating conditions such as the nature and flow of the silane compound, the duration of the treatment, the pressure used, the nature of the flame, the distance of the burner from the part to be treated, can be easily adapted and selected by a person skilled in the art to obtain the desired properties.

[0049] In a particular embodiment, the first layer may undergo at least one surface oxidation step prior to the Sionization process. This Surface oxidation can be achieved without a silane-type reaction precursor, either by flame or by atmospheric pressure plasma. These can be referred to respectively as oxidizing flame and oxidizing plasma.

[0050] This preliminary step to the formation of the second layer by Sionization (i.e. flame with a precursor of the silane compound type) advantageously improves the adhesion between the first layer and the second layer.

[0051] Operating conditions such as plasma power and treatment duration can be easily adapted and selected by a person skilled in the art to obtain the desired properties.

[0052] Other features and advantages of the present invention will become apparent from the description of non-limiting examples.

[0053] Examples Manufacturing of an element according to the invention using the flame process The support used as the first layer is an aluminum sample, in the form of a rectangular plate with the following dimensions: 15 cm long, 5 cm wide, and 1.5 mm thick.

[0054] The process used to directly deposit a silica layer as a second layer is a flame-bonding process.

[0055] The flame treatment process is carried out using a device marketed by the company Arcotec GmbH under reference 61854.

[0056] This device is combined with a robot. The part to be processed is, in this example, the rectangular aluminum plate.

[0057] The following parameters were used: - Flame composed of a mixture of air and propane, with the following consumptions: 100 L / min of pure oxygen and 4.8 L / min of propane; - Oxygen supply: 5 - 8 bar; - Propane supply: 6 - 8 bar; - Silane compound used: hexamethyldisiloxane (HMDSO) - Consumption of the silane compound: 0.35 mL / min (i.e. 0.17 mL / min for 100 L / min of the oxygen and propane mixture); - Distance between the burner outlet and the surface of the rectangular plate to be treated: approximately 5-6 cm; - Flame height: approximately 8 cm; - Flame width: approximately 10 cm; - Robot speed: 300 mm / s.

[0058] Once the rectangular plate is positioned lengthwise on the robot's gripper, it passes through the flame across its entire width (in this example, the width of the flame is greater than the width of the rectangular plate to be treated). From this In fact, a single pass under the flame is sufficient to treat the entire surface of the plate exposed to the flame.

[0059] This gives us a first layer of aluminium comprising a second layer of silicate deposited directly on its surface, the second layer having a thickness of approximately 40 nm.

[0060] The treated plate is then painted with a robotic three-layer application: primer, base and varnish.

[0061] Various tests were carried out on the part thus treated and painted. These tests are summarized in the table below: [Tables 1] Test Name Operating Conditions Test Result Initial Adhesion Make a grid using a multi-blade cutter with 1.5 mm spacing. Apply a specific adhesive tape to the grid and tear it off sharply. There is no delamination. Pressure Washer Make a St. Andrew's cross on the plate and then apply the pressure washer jet of water to the center of the cross from a distance of 10 cm, for 1 minute at 60°C. There is no delamination. Humidity Resistance Place the sample in an environment with 95 ± 5% relative humidity at 48 ± 2°C for 240 hours. There is no bubbling, no degradation of the coating, and no loss of adhesion. Immersion resistance: Immerse the sample in a deionized water chamber with a resistivity greater than 200,000 Ω·cm, at a temperature of 32 ± 2°C for 240 hours. Then perform an initial adhesion test one hour after removing the sample. There is no bubbling or loss of adhesion.Salt spray resistance: Place the sample in an enclosure containing salt spray, a saline solution of 5 + 0.5% by mass of NaCl solution and 95% by mass of water. There is no blistering, oxidation, or loss of adhesion. demineralized water, at a temperature of 35±2°C for 500 hours. Then perform a scratch test on the samples.

Claims

Claims

1. An anti-corrosion and adhesion promoting element between a first layer and a top coating of paint type, characterized in that the element comprises a first layer formed by a ferrous, non-ferrous metallic material or glass and a second layer deposited based on a silicon compound comprising one or more silicon-oxygen group(s).

2. Element according to claim 1, characterized in that the second layer has a thickness of at most 150 nm.

3. Element according to claim 1 or 2, characterized in that the second layer is a hydrophilic layer.

4. Element according to any one of the preceding claims, characterized in that the second layer is in direct physical contact with the first layer.

5. Element according to any one of the preceding claims, characterized in that the second layer is a silicate layer or an organosilicate layer.

6. Element according to claim 5, characterized in that the silicate or organosilicate layer is obtained from a silane compound.

7. Element according to claim 6, characterized in that the silane compound is chosen from a hydrocarbon silane, a fluorosilane, a silicate, an organosilicate, and one of their mixtures.

8. Element according to claim 7, characterized in that the hydrocarbon silane is tetramethylsilane (TMS).

9. Element according to claim 7, characterized in that the fluorosilane is triethoxyfluorosilane (TEOF).

10. Element according to claim 7, characterized in that the organosilicate is chosen from tetraethoxysilane (TEOS), tetramethoxylsilane (TMOS), and one of their mixtures.

11. Element according to any one of claims 1 to 4, characterized in that the second layer is a layer of polysiloxane.

12. Element according to claim 11, characterized in that the polysiloxane layer is obtained from a siloxane monomer or a silazane monomer.

13. Element according to claim 12, characterized in that the siloxane monomer is chosen from hexamethyldisiloxane (HMDSO),

14.

15.

16.

17. tetramethyldisiloxane (TMDSO), octamethylcyclotetrasiloxane (OMCTSO), and a mixture thereof. Element according to claim 12, characterized in that the silazane monomer is hexamethyldisilazane (HMDSN). Element according to any one of the preceding claims, characterized in that the material is ferrous, non-ferrous metal, or glass. Method of manufacturing an element according to any one of the preceding claims; characterized in that the carrier gas of the silane compound is dioxygen or oxygen (O2). A method of manufacturing an element according to any one of the preceding claims; characterized in that the second layer is formed using flame treatment.