Infusion process for the manufacture of a composite part comprising anti-infrared pigments.

Abstract

The invention relates to a method for manufacturing a molded part, in particular for a motor vehicle, the molded part being produced 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 the at least one textile part (1) on the thermal barrier (2), - a step of depositing an anti-adhesion means (4) on the at least one textile part (1), - a step of depositing a drainage means (5) on said anti-adhesion means (4), - a step of injecting (Inj) a stiffening binder (6) inside the mold so that the stiffening binder connects the thermal barrier to the at least one textile part,and - a step of infusion by depressurization (D) of the mold (3) such that the thermal barrier (2) migrates in whole or in part towards the stiffening binder (6) and / or towards the at least one textile piece (1). Figure for the abstract: [Fig.1],

Description

Title of the invention: Infusion method for manufacturing a composite part comprising anti-infrared pigments.

[0001] 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 bodywork panel, comprising a thermal barrier.

[0002] It is known that parts, in particular those of a motor vehicle, and more particularly bodywork parts, have a variable degree of reflection of light rays depending on the color of the part. A white color gives this part a higher reflection than a dark color, which results in less heat transfer for light colors, and therefore a lower temperature inside the passenger compartment, for example.

[0003] Anti-infrared pigments are known, and are even used in paints that are applied to the surface of a part. Due to a surface coating, the reflection capacity of the paint layer comprising the anti-infrared pigments is low, in particular is linked to the thickness of the paint layer. It is from this observation that the present invention arises. It is important and necessary to improve the current solution for heat treatment of parts, in particular composite parts intended for a vehicle, by a new process which makes it possible to reduce the absorption of heat by a part subjected to infrared rays.

[0004] The subject of the present invention relates to a method for manufacturing a molded part, in particular for a motor vehicle, the molded part being produced from at least one textile part, 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 inside a mold, the thermal barrier comprising anti-infrared pigments, - a step of depositing at least one textile piece on the thermal barrier, - a step of depositing an anti-adhesion means on the at least one textile piece, said anti-adhesion means is in particular of the peelable skin type, - a step of depositing a drainage means on said anti-adhesion means, the drainage means being notably produced from a resin mesh, - a step of injecting a stiffening binder inside the mold such that the stiffening binder connects the thermal barrier to the at least one textile part, the stiffening binder being in particular of the epoxy resin type, and - 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 piece.

[0005] The infusion effect aims to create an impression of the thermal barrier in the textile piece and / or in the stiffening binder, such that a transfer of a quantity of the anti-infrared pigments previously present in the thermal barrier takes place towards the textile piece and / or the stiffening binder.

[0006] According to other particularities, the manufacturing method may comprise the following characteristics taken separately or in combination with each other: - the step of depositing the thermal barrier consists of the application of several passes of a liquid base comprising the anti-infrared pigments, each pass producing a layer with a thickness of between 0.2 and 1 mm, preferably with a thickness of 0.5 mm; - the infusion step by depressurization of the mold consists of applying an air depression of between 0.5 Bar and 2 Bar, preferably around 1 Bar; - the thermal barrier is made from a liquid based on epoxy or unsaturated polyester resin with an anti-infrared pigment content of between 10% and 30% by mass, preferably 15% by mass; - the stiffening binder comprises anti-infrared pigments whose volume content is between 2% and 10%, preferably 5% by volume; - at least one textile piece has a density between 200g / m2 and 630g / m2; - the depressurization infusion step is carried out according to a cooking cycle taking into account the temperature of the mold, such that at room temperature between 15°C and 30°C, the cooking cycle has a duration of approximately 4 hours with the mold heating to approximately 140°C, followed in particular by post-cooking lasting approximately 1 hour with the mold heating to approximately 180°C; - it comprises a step of depositing an anti-adhesion means on the at least one textile piece; - it comprises a step of depositing a drainage means and / or a sealing means inside the mold, in particular in the upper part of the mold.

[0007] The invention also relates to a part, in particular an appearance part made of 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 method, such that the part comprises a thermal barrier comprising anti-infrared pigments in particular infused in whole or in part in the textile part and / or in the stiffening binder.

[0008] The drawing in [Fig.l] represents, by way of example, the means of implementing the manufacturing method which will be described below.

[0009] The subject 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.

[0010] The manufacturing method comprises the steps which will be described in the following. One of the steps consists first of all in the preparation of a liquid base, also known by the English terminology "gelcoat", containing a transparent gel which is mixed with pigments highly reflective to infrared. For example, the pigments are based on iron and chromium oxide, and represent approximately between 10% and 30% by mass of the liquid base, preferably of the order of 15%. For example, the transparent gel can be based on vinylester resin. Due to its anti-infrared properties, the liquid base can also be described as a thermal barrier. The liquid base thus produced is an anti-infrared pigmented base which can be intended for application on a support by spraying, in particular by an air pressure spray gun. Advantageously, the use of a spray gun allows the production of a thin layer, or even several thin layers superimposed on each other.

[0011] One of the steps consists of producing at least one textile piece. Preferably, the textile piece is produced from a fiber. Preferably again, the method consists of producing two textile pieces assembled by superimposing one on the other. For example, one of the textile pieces could have a fiber orientation in a direction that is different from the fiber orientation of the other of the textile layers. Each textile piece is produced from a fiber chosen in particular from carbon and glass.

[0012] According to an alternative embodiment, it could also be possible to create a stack of textile pieces of different materials.

[0013] For example, the textile is made from a carbon or glass fiber, using a weaving process. The textile has a density that is between 200 g / m2 and 630 g / m2.

[0014] The manufacturing process requires for its implementation, a mold provided with a matrix 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.

[0015] According to the manufacturing method, the previously prepared liquid base is deposited by a spraying process inside a mold intended for the manufacture of a part obtained by a process of molding a composite material. 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 deposit of a liquid base layer with a thickness of between 0.2 mm and 1 mm. Preferably, the thermal barrier is produced by applying several successive passes of liquid base inside the mold, in particular four passes, in order to deposit, at each pass, a thickness of liquid base which is of the order of 0.5 mm. This makes it possible to produce a layer of homogeneous thickness of liquid base on the mold impression.

[0016] The manufacturing method then comprises an operation of depositing at least one previously woven textile piece inside the mold, such that the textile piece is positioned above the thermal barrier.

[0017] According to a preferred embodiment, two textile pieces are positioned one on top of the other, on the thermal barrier.

[0018] At this stage, a stack of a thermal barrier and at least one textile piece is created.

[0019] The manufacturing method then consists of depositing an anti-adhesion means on the textile part. Said anti-adhesion means is also referred to as 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 whose thickness is between 100 and 200 microns, preferably around 120 microns. At this stage, a stack of a thermal barrier, at least one textile part and a peelable skin is created.

[0020] The method then consists of depositing a drainage means, made from a resin mesh. The drainage means is intended to distribute in a predetermined manner the resin which will be injected into the mold to produce the molded anti-infrared part. Advantageously, said drainage means promotes the flow of injected resin for impregnating the textile.

[0021] According to an alternative embodiment, the anti-adhesion and drainage means form a single part so that the manufacturing method contains one less removal step. For example, the anti-adhesion means can be attached against the drainage means during the manufacturing of the latter. The anti-adhesion means can be fixed in an adhesive manner on one face of the drainage means.

[0022] The anti-adhesion means is a mesh made of resin, the role of which is to guide the stiffening resin which will be injected inside the mold, in different areas of the at least one textile piece.

[0023] The method then consists of the removal of a sealing wall, in particular made from a plastic material, which aims to guarantee sealing in particular at air. The sealing wall is intended to be inserted between an upper face of the drainage means and the punch of the mold. At this stage, a stack of a thermal barrier, at least one textile piece, a peelable skin, a resin mesh and a sealing screen is created.

[0024] The mold can then be closed so that the aforementioned stacking is achieved by shaping the textile piece according to the mold imprint.

[0025] The manufacturing method then consists of injecting a stiffening binder, made mainly from an epoxy resin, inside the mold which will first be inserted between the at least one textile piece and the peelable skin, as well as between the textile piece and the anti-infrared barrier. The at least one textile piece is then covered from above and below with the injected stiffening binder, before gradually migrating by capillarity within the at least one textile piece. The stiffening resin is a binder which will allow the aggregation of the elements previously positioned inside the mold. The at least one textile is immersed in the stiffening binder which penetrates into the mesh of the at least one textile piece.

[0026] The amount of stiffening resin is injected under a pressure of 1 Bar, preferably at room temperature. The temperature of the stiffening resin to be injected must be between 18°C and 23.5°C degrees, so that it could be heated or cooled depending on the room temperature in order to maintain the viscosity properties required for satisfactory impregnation of the at least one textile piece. According to one embodiment, the stiffening resin is an epoxy resin.

[0027] Given that the thermal barrier is still in the aqueous state at the time of injection of the stiffening binder, the thermal barrier will gradually migrate towards the stiffening resin.

[0028] To homogenize the thermal barrier in the molded part, a step of depressurizing the mold is carried out, which tends to create an infusion effect of the thermal barrier towards the stiffening binder, but also towards the at least one textile part. For example, the depressurization is between 0.5 Bar and 2 Bar, preferably 1 Bar. This improves the migration of the thermal barrier in the textile part, in particular via at least one of the layers of stiffening binder.

[0029] Preferably, the depressurization takes place over a period of time between 1 hour and 5 hours. Preferably again, the depressurization takes place at a temperature between 100°C and 200°C degrees.

[0030] In particular, the depressurization step is carried out in two successive steps, namely a cooking step followed by a post-cooking step. The curing step may last approximately 4 hours with a mold temperature raised to approximately 140°C, followed by a post-curing step which may last approximately 1 hour under an increased mold temperature, for example approximately 180°C, especially when the ambient temperature is between 15°C and 30°C.

[0031] Advantageously, the stiffening binder may comprise, 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.

[0032] 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 said drainage means is removed and then discarded.

[0033] The part resulting from the implementation of the manufacturing method detailed above may be a composite bodywork part. For example, it could be a structural part visible from the inside or outside of the vehicle, which is likely to be in contact with infrared rays. Advantageously, such a part does not diffuse the heat emitted by the infrared rays. In a situation of application to an automobile bodywork part, it has been noted that the temperature inside the passenger compartment is lowered, compared to a traditional bodywork, such that the application of such a method makes it possible to effectively create a thermal barrier on parts made of composite material.

[0034] The use of this method of infusing the thermal barrier into the composite part is remarkable in that the anti-infrared pigments are present in the mass of the molded composite part. Due to the infusion of the thermal barrier towards the textile part, or at least towards the stiffening binder, the thermal barrier is thus not a sacrificial layer which could be partly removed in the case of a scratch.

Claims

Claims

1. A method of manufacturing a molded part, in particular 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 the at least one textile part (1) on the thermal barrier (2), - a step of depositing an anti-adhesion means (4) on the 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 in particular made from a resin mesh,- a step of injecting (Inj) a stiffening binder (6) inside the mold such that the stiffening binder connects the thermal barrier to the at least one textile piece, the stiffening binder being in particular of the epoxy resin type, and - a step of infusion by depressurization (D) of the mold (3) such that the thermal barrier (2) migrates in whole or in part towards the stiffening binder (6) and / or towards the at least one textile piece (1).,

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

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

4. 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 whose anti-infrared pigment content is between 10% and 30% by mass, preferably 15% by mass.

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

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

7. Method 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 room 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 lasting approximately 1 hour with a mold temperature of approximately 180°C.

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

9. 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 top 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 produced by implementing the method according to at least one of claims 1 to 9, such that the part comprises a thermal barrier (2) comprising anti-infrared pigments in particular infused in whole or in part in the textile part (1) and / or in the stiffening binder (6).

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