Infusion process for manufacturing a composite part comprising Anti-infrared pigments

Abstract

The invention relates to a process for manufacturing a moulded part, especially for a motor vehicle, the moulded part being produced using at least one textile part (1), the textile part comprising at least one fibre, especially a glass or carbon fibre, the process comprising: - a step of placing a thermal barrier (2) inside a mould (3), the thermal barrier comprising anti-infrared pigments, - a step of placing the at least one textile part (1) on the thermal barrier (2), - a step of placing an anti-adhesion means (4) on the at least one textile part (1), - a step of placing a drainage means (5) on the anti-adhesion means (4), - a step of injecting (Inj) a stiffening binder (6) into the mould such that the stiffening binder joins the thermal barrier to the at least one textile part, and - a step of achieving infusion by depressurisation (D) of the mould (3) such that all or some of the thermal barrier (2) migrates towards the stiffening binder (6) and / or towards the at least one textile part (1).

Description

[0001] DESCRIPTION

[0002] TITLE: Infusion process for the manufacture of a composite part containing anti-infrared pigments.

[0003] The invention relates to a method for manufacturing a composite part, in particular intended for a motor vehicle, in particular of the type of an appearance part, such as a body panel, comprising a thermal barrier.

[0004] It is known that parts of a motor vehicle, particularly body parts, have varying degrees of light reflection depending on their color. White gives a part greater reflection than dark colors, resulting in less heat transfer for light colors, and therefore a lower temperature inside the passenger compartment, for example.

[0005] Infrared-blocking pigments are known and even used in paints applied to the surface of a part. Due to the surface coating, the reflectivity of the paint layer containing the infrared-blocking pigments is low, particularly related to the thickness of the paint layer. The present invention stems from this observation. It is important and necessary to improve the current heat treatment methods for parts, especially composite parts intended for vehicles, by using a new process that reduces heat absorption by a part exposed to infrared radiation.

[0006] The object of the present invention relates to a method for manufacturing a molded part, particularly for a motor vehicle, the molded part being made from at least one textile piece, said textile piece comprising at least one fiber, in particular a carbon or glass fiber, the method comprising:

[0007] - a step involving the application of a thermal barrier inside a mold, the thermal barrier containing anti-infrared pigments,

[0008] - a step involving the placement of at least one piece of textile onto the thermal barrier,

[0009] - a step of applying an anti-adhesion agent to at least one textile part, said anti-adhesion agent being in particular of the peelable skin type,

[0010] - a step of depositing a drainage means onto said anti-adhesion means, the drainage means being notably made from a resin mesh,

[0011] - a step of injecting a stiffening binder inside the mold such that the stiffening binder connects the thermal barrier to at least one textile part, the stiffening binder being in particular of the epoxy resin type, and

[0012] - an infusion step by depressurizing the mold so that the thermal barrier migrates in whole or in part towards the stiffening binder and / or towards at least one textile part. The infusion effect aims to create an impression of the thermal barrier in the textile part and / or in the stiffening binder, so that a transfer of a quantity of the anti-infrared pigments previously present in the thermal barrier to the textile part and / or the stiffening binder takes place.

[0013] Depending on other specific characteristics, the manufacturing process may include the following features, taken separately or in combination:

[0014] - the thermal barrier application step consists of applying several passes of a liquid base containing anti-infrared pigments, each pass creating a layer with a thickness between 0.2 and 1 mm, preferably 0.5 mm thick; - the mold depressurization infusion step consists of applying an air vacuum of between 0.5 Bar and 2 Bar, preferably around 1 Bar;

[0015] - the thermal barrier is made from a liquid based on epoxy resin or unsaturated polyester with an anti-infrared pigment content of between 10% and 30% by mass, preferably 15% by mass;

[0016] - the stiffening binder includes anti-infrared pigments with a volume content of between 2% and 10%, preferably 5% by volume;

[0017] - at least one piece of textile has a density between 200g / m 2 and 630 g / m 2 ;

[0018] - the depressurization infusion stage is carried out according to a cooking cycle taking into account the temperature of the mold, so that at an ambient temperature between 15°C and 30°C, the cooking cycle lasts approximately 4 hours with a mold temperature of approximately 140°C, followed in particular by a post-cooking lasting approximately 1 hour with a mold temperature of approximately 180°C;

[0019] - it includes a step of applying an anti-adhesion agent to at least one piece of textile;

[0020] - the placement of said drainage means inside the mold is carried out in the upper part of the mold;

[0021] - it includes a step of depositing a sealing means inside the mold, in particular in the upper part of the mold.

[0022] The invention also relates to a part, in particular an appearance part made of a composite material, such as a textile part comprising at least one fiber, in particular a carbon or glass fiber, and a stiffening binder, in particular epoxy, the part being produced by implementing the aforementioned process, such that the part includes a thermal barrier comprising anti-infrared pigments, in particular infused wholly or partly into the textile part and / or into the stiffening binder. The drawing in [Fig. 1] represents, by way of example, the means of implementing the manufacturing process which will be described below.

[0023] The object of the invention relates to a method for manufacturing a part, in particular a part made from a resin, which could be intended for a vehicle, in particular an automobile.

[0024] The manufacturing process includes the steps that will be described below.

[0025] One of the steps involves the initial preparation of a liquid base, also known as a gelcoat, containing a transparent gel mixed with highly infrared-reflective pigments. For example, the pigments are iron and chromium oxide-based and represent approximately 10% to 30% by mass of the liquid base, preferably around 15%. The transparent gel itself, for instance, can be vinyl ester-based.

[0026] Due to its anti-infrared properties, the liquid base can also be described as a thermal barrier.

[0027] The resulting liquid base is an infrared-resistant pigmented base suitable for application to a substrate by spraying, particularly with an air pressure spray gun. Advantageously, using a spray gun allows for the application of a thin layer, or even several thin layers superimposed on one another.

[0028] One of the steps involves creating at least one textile component. Preferably, the textile component is made from a single fiber. Even more preferably, the process involves creating two textile components joined by layering one on top of the other. For example, one of the textile components could have fibers oriented in a different direction than the other textile layer. Each textile component is made from a fiber chosen from among others, such as carbon and glass.

[0029] According to one alternative embodiment, it might also be possible to create a stack of textile pieces made of different materials.

[0030] For example, the textile is made from carbon or glass fiber, using a weaving process. The textile has a density of between 200 g / m² 2 and 630 g / m 2 .

[0031] The manufacturing process requires, for its implementation, a mold equipped with a die and a punch, an impression having been made in the mold in a traditional manner, according to the shape of the part in its configuration after molding. Depending on the manufacturing process, the previously prepared liquid base is deposited by a spraying process inside a mold intended for the manufacture of a part obtained by a molding process of a composite material.

[0032] Preferably, the process is carried out in such a way that a thermal barrier is deposited inside the mold, in several successive passes. Each pass allows the deposition of a liquid base layer with a thickness between 0.2 mm and 1 mm.

[0033] Preferably, the thermal barrier is created by applying several successive passes of liquid base inside the mold, specifically four passes, in order to deposit a layer of liquid base approximately 0.5 mm thick with each pass. This allows for a homogeneous layer of liquid base on the mold cavity.

[0034] The manufacturing process then includes an operation of depositing at least one piece of pre-woven textile inside the mold, so that the piece of textile is positioned above the thermal barrier.

[0035] According to a preferred embodiment, two textile pieces are positioned one on top of the other, on the thermal barrier.

[0036] At this stage, a stack of a thermal barrier and at least one piece of textile is created.

[0037] The manufacturing process then consists of applying an anti-adhesion coating to the textile part. This anti-adhesion coating is also called a peelable skin because it can be easily removed from the molded part, as will be detailed below. The peelable skin can be made from a polyamide sheet with a thickness between 100 and 200 microns, preferably around 120 microns.

[0038] At this stage, a layer of a thermal barrier, at least one piece of textile and a peelable skin is created.

[0039] The process then consists of applying a drainage system, made from a resin mesh. This drainage system is designed to distribute the resin, which will be injected into the mold to create the molded infrared-blocking part, in a predetermined manner. Advantageously, this drainage system facilitates the flow of injected resin for impregnation of the textile.

[0040] In one embodiment, the anti-adhesion and drainage means form a single unit, thus reducing the manufacturing process by one deposition step. For example, the anti-adhesion means can be attached to the drainage means during the latter's manufacture. The anti-adhesion means can be bonded to one face of the drainage means.

[0041] The anti-adhesion device is a mesh made of resin, whose role is to guide the stiffening resin which will be injected inside the mold, in different areas of at least one textile piece.

[0042] The process then involves installing a sealing wall, typically made from a plastic material, designed to ensure airtightness. This sealing wall is positioned between the upper surface of the drainage system and the mold punch.

[0043] At this stage, a stack of a thermal barrier, at least one piece of textile, a peelable skin, a resin mesh and a sealing screen is created.

[0044] The mold can then be closed in such a way that the aforementioned stacking is achieved by shaping the textile piece according to the mold's imprint.

[0045] The manufacturing process then consists of injecting a stiffening binder, primarily made from epoxy resin, into the mold. This binder is initially placed between the textile component and the peelable skin, as well as between the textile component and the infrared barrier. The textile component is then coated from both the top and bottom with the injected stiffening binder, before gradually migrating by capillary action within the textile component. The stiffening resin acts as a binder, facilitating the aggregation of the elements previously positioned inside the mold. The textile component is immersed in the stiffening binder, which penetrates the fabric's structure.

[0046] The stiffening resin is injected under a pressure of 1 bar, preferably at ambient temperature. The temperature of the injected stiffening resin must be between 18°C ​​and 23.5°C, such that it can be heated or cooled according to ambient temperature to maintain the viscosity properties required for satisfactory impregnation of at least one textile component.

[0047] According to one embodiment, the stiffening resin is an epoxy resin.

[0048] Given that the thermal barrier is still in an aqueous state at the time of injection of the stiffening binder, the thermal barrier will gradually migrate towards the stiffening resin.

[0049] To homogenize the thermal barrier within the molded part, a mold depressurization step is performed. This tends to create an infusion effect of the thermal barrier into the stiffening binder, as well as into at least one textile component. For example, the depressurization is typically between 0.5 bar and 2 bar, preferably 1 bar. This improves the migration of the thermal barrier into the textile component, particularly through at least one of the stiffening binder layers.

[0050] Preferably, the depressurization takes place over a period of time between 1 and 5 hours. Even more preferably, the depressurization takes place at a temperature between 100°C and 200°C.

[0051] In particular, the depressurization step takes place in two successive stages, namely a cooking stage followed by a post-cooking stage.

[0052] The baking stage can last approximately 4 hours with the mold temperature raised to approximately 140°C, followed by a post-baking stage which can last approximately 1 hour under an increased mold temperature, for example approximately 180°C, particularly when the ambient temperature is between 15°C and 30°C.

[0053] Advantageously, the stiffening binder can include, before injection into the mold, a content of anti-infrared pigments, in particular identical to those of the thermal barrier, which represents a content of between 2% and 10% by volume, preferably 5% by volume.

[0054] Once the infusion cycle is complete, the anti-infrared composite part is demolded. The assembly, consisting of the peelable skin and the resin mesh forming the drainage system, is removed and discarded.

[0055] The part resulting from the manufacturing process detailed above can be a composite body panel. For example, it could be a structural part visible from the inside or outside of the vehicle that is likely to come into contact with infrared radiation. Advantageously, such a part does not diffuse the heat emitted by infrared radiation. In the context of application to an automotive body panel, it has been observed that the temperature inside the passenger compartment is lowered compared to a traditional body panel, such that the application of this process effectively creates a thermal barrier on parts made of composite material.

[0056] The use of this thermal barrier infusion process within the composite part is remarkable because the infrared-resistant pigments are present throughout the molded composite material. Because the thermal barrier is infused into the textile component, or at least into the stiffening binder, it is not a sacrificial layer that could be partially removed in the event of a scratch.

Claims

DEMANDS 1. A method for manufacturing a molded part, particularly for a motor vehicle, the molded part being made from at least one textile part (1), said textile part comprising at least one fiber, in particular a carbon or glass fiber, the method comprising: - a step of depositing a thermal barrier (2) inside a mold (3), the thermal barrier comprising anti-infrared pigments, - a step of depositing at least one textile piece (1) onto the thermal barrier (2), - a step of applying an anti-adhesion means (4) to at least one textile part (1), said anti-adhesion means being in particular of the peelable skin type, - a step of depositing a drainage means (5) on said anti-adhesion means (4), the drainage means being made in particular from a resin mesh, - a step of injecting (Inj) a stiffening binder (6) into the mold such that the stiffening binder connects the thermal barrier to at least one textile piece, the stiffening binder being in particular of the type of an epoxy resin, and - a step of infusing by depressurization (D) the mold (3) such that the thermal barrier (2) migrates in whole or in part towards the stiffening binder (6) and / or towards at least one textile piece (1).

2. A method according to the preceding claim, characterized in that the step of depositing the thermal barrier (2) consists of applying several passes of a liquid base comprising the anti-infrared pigments, each pass producing a layer of thickness between 0.2 and 1 mm, preferably of thickness 0.5 mm.

3. Method according to the preceding claim, characterized in that the depressurization infusion step (D) of the mold (3) consists of applying an air depression of between 0.5 Bar and 2 Bar, preferably about 1 Bar.

4. A method according to any one of the preceding claims, characterized in that the thermal barrier (2) is made from a liquid based on epoxy resin or unsaturated polyester having an anti-infrared pigment content of between 10% and 30% by mass, preferably 15% by mass.

5. A method according to any one of the preceding claims, characterized in that the stiffening binder (6) comprises anti-infrared pigments having a volume content of between 2% and 10%, preferably 5% by volume.

6. A method according to any one of the preceding claims, characterized in that at least one textile piece (1) has a density of between 200 g / m². 2 and 630 g / m2 .

7. A process according to any one of the preceding claims, characterized in that the depressurization infusion step (D) is carried out according to a cooking cycle taking into account the temperature of the mold, such that at an ambient temperature between 15°C and 30°C, the cooking cycle has a duration of approximately 4 hours with a mold temperature of approximately 140°C, followed in particular by a post-cooking of a duration of approximately 1 hour with a mold temperature of approximately 180°C.

8. A method according to any one of the preceding claims, characterized in that the deposition of said drainage means (5) inside the mold (3) is carried out in the upper part of the mold.

9. A method according to any one of the preceding claims, characterized in that it comprises a step of depositing a sealing means (7) inside the mold (3), in particular in the upper part of the mold.

10. Part, in particular an appearance part made of composite material, such as a textile part (1) comprising at least one fiber, in particular a carbon or glass fiber, and a stiffening binder (6), in particular epoxy, the part being made by implementing the process according to at least one of claims 1 to 9, such that the part includes a thermal barrier (2) comprising anti-infrared pigments in particular infused in whole or in part into the textile part (1) and / or into the stiffening binder (6).

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