DE102009039860B4 - Process for the preparation of a composite component made of polyurethane sandwich materials with Class A covering layer and composite component produced by the process - Google Patents

Abstract

Method for producing a composite part (01), characterized in that the production takes place in the following process steps: (Aa) clamping a first fiber fabric (08a) next to a tool (10) required for the first process; (Ab) spraying the first fibrous web (08a) with a polyurethane preparation (07a); (Ac) inserting the polyurethane (07a) soaked first fibrous web (08a) into the tool (10); (Ad) inserting a paper honeycomb layer (04) in the tool on the first polyurethane (07a) soaked fiber fabrics (08a); (Ae) clamping a second fiber fabric (08b); (Af) spraying the second fibrous web (08b) with a polyurethane formulation (07b); (Ag) inserting the polyurethane (07b) soaked second fibrous web (08b) into the tool (10) onto the paper honeycomb layer (04); (Ah) closing the tool (10); (Ai) at least substantial curing of the polyurethane (07) at elevated pressure and / or elevated temperature to form a load-bearing layer sequence (06); (Aj) removal of the load-bearing layer sequence (06) from the first tool (10); either (Ba) inserting the load-bearing layer sequence (06) from the first process step into a second tool (13) for the second process step; (Bb) closing the second tool (13), wherein in the mold cavity of the second tool (13) a defined gap remains on one side of the second tool (13) and thus forms a cavity (16); (Bc) filling the cavity (16) with a polyurethane composition; or that the step (Bc) of filling with a polyurethane preparation before the step (Bb) of closing the second tool (13), as this is a polyurethane composition on the at least substantially cured bearing layer sequence (06) is applied and in the sequence the second tool (13) is closed; (Bd) curing the polyurethane (02) at elevated pressure and / or elevated temperature to form a Class A-grade topcoat; (Be) removal of the finished composite part (01).

Description

The invention relates to a method for producing a composite component of polyurethane sandwich materials with a Class A cover layer, which has a particularly high quality. Furthermore, the invention relates to a component produced by the method.

Various methods and structures for composite components are known from the prior art, which in turn consist primarily of PU sandwich materials. The common structure consists of a glass fiber reinforced polyurethane layer, followed by a paper honeycomb as an intermediate layer and another glass fiber reinforced polyurethane layer. This layer sequence has a very high strength and very low weight. A disadvantage of this design, however, is that the surface is not suitable to achieve a perfect surface by simply painting.

Particularly in the automotive industry there is a demand for Class A surfaces in the outdoor area, where Class A means a perfect, defect-free and homogeneous surface. This can be dyed already finished in the desired color as well as be painted or executed in such a way that the final color is produced by a painting. Occasionally it is the case that certain surface defects appear even more pronounced by painting than they would have been previously recognizable. In order to meet the demand from the automotive industry for Class A surfaces and at the same time to achieve a lightweight component, in a known manner, the composite component of polyurethane sandwich materials in a subsequent operation initially primed to finally be painted. It is thus easy to see that the process used in the multi-stage process leads to relatively high component costs.

If the multi-layered construction with a paper honeycomb is dispensed with, this can be done from the US 2002/0195742 A1 known methods are used. Here, a PU layer is first produced in a tool, wherein the setting of a suitable pressure and elevated temperatures enables a Class-A surface. Subsequently, a further fiber-reinforced PU layer is produced in the same tool on the back of the PU layer previously produced, while maintaining the Class-A quality. A single-layer fiber-reinforced construction with a Class-A surface is used in the US 5,391,344 A discloses wherein a fabric web is placed over the fiberglass mat to prevent the picking of glass fibers at the desired Class A surface in the tool.

In order to reduce the process costs, it is proposed, inter alia in the prior art, to bond the composite component made of PU sandwich materials with a film or a preformed final component. Sometimes this can be the final painting saved. However, the continuous thermal cycling can lead to permanent damage. Due to different expansion coefficients of the different materials, it comes in particular between the composite component and the cover layer to release phenomena and thus dents on the surface. Likewise, even with this structure, the resulting costs are not appreciably lower than in the priming and painting process.

To improve the previously indicated solution proposes the font DE 102 29 473 A1 To combine the surface with Class-A quality in one operation with the production of polyurethane composite body with this. For this purpose, deep-drawn sheets, preferably metal sheets, are used, which have the necessary component shape. These are inserted into the tool for producing the composite component and subsequently the layer sequence of fiber-reinforced polyurethane, paper honeycomb and in turn fiber-reinforced polyurethane is applied. As an alternative to the metal sheets, higher-strength plastic films may be considered, it being particularly true to maintain the Class A surface quality under the elevated reaction temperatures, whereby in particular the honeycomb structure presses into the inserted film due to the closing of the tool.

Although the proposed method simplifies and improves the bonding of the surface to the polyurethane composite, there remains a high manufacturing cost for thermoforming the films and the increased cost of the high strength thick Class A film.

The object of the invention is now to provide a composite component of PU sandwich materials, which has on one side a Class-A surface and thereby is inexpensive to produce.

It is another object of the invention to provide a corresponding method for producing that composite component.

To solve this problem, it is proposed to use a composite component of polyurethane sandwich materials, which consists of a fiber-reinforced polyurethane layer, a paper honeycomb intermediate layer and another fiber-reinforced polyurethane layer, on the Finally, in turn, a polyurethane layer is applied.

The fact that a polyurethane layer is chosen as the conclusion again, thus overcome two of the aforementioned disadvantages. On the one hand, all materials thus have approximately equal coefficients of expansion, and on the other hand is ensured by the polyurethane layer on the polyurethane-reinforced fiber layer that a solid bond is maintained, without causing peeling phenomena.

Furthermore, in the process according to the invention, the final layer is produced in one operation, the application of the polyurethane. By contrast, always two steps are necessary in the methods of the prior art, whereby the required saving effect is achieved.

The structure of the composite component initially consists of the classical materials, insofar as a fiber-reinforced layer, in this case preferably a glass fiber, is used, which is enclosed in a corresponding polyurethane matrix. According to the invention, the use of a paper honeycomb is provided as an intermediate layer. In this case, with a very low density of the material, the necessary distances between the fiber-reinforced layers can be produced. It is also possible to use a plastic foam layer. The second fiber-reinforced layer is substantially identical to the first fiber-reinforced layer and is preferably also made of glass fibers which are included in the polyurethane matrix.

The strength in the fiber-reinforced polyurethane layers and thus the supporting layer structure is largely determined by the fibers or glass fibers. Accordingly, it is advantageous to strive for the proportion in the layers to be as high as possible. This must be above 30% in any case, but should be advantageously about 60%.

In the production of the composite component, it is technically advantageous if the paper honeycomb layer extends over the entire component. Since the material is usually compressed locally to a minimum height in the circumferential region, the paper honeycomb layer is consequently likewise pressed. The same applies in functional areas where the space is insufficient and in the composite component a corresponding dent or the like must be introduced.

Since the paper honeycomb layer in itself has no supporting function and is only intended to produce the distance between the two supporting layers, it preferably has a minimum density, which is below 0.1 g / cm ³ for this purpose. When using a paper honeycomb as an intermediate layer according to the invention, this is achieved inter alia by the fact that the inside diameter (theoretical cylinder which can be inserted into the free space) of each honeycomb is selected to be large, ie over 2 mm, advantageously over 4 mm.

The paper honeycomb layer has its significance for producing a bending-resistant composite component as a spacer between the two load-bearing fiber-reinforced layers. According to the possibilities with regard to the available installation space in the later use, the paper honeycomb layer preferably has a large thickness. For this purpose, this is preferably over 5 mm.

In the case of substantially planar components, this embodiment is particularly advantageous, in which case component thicknesses of the composite between 5 and 20 mm are appropriate and advantageous for the purpose of use.

The surface of the composite component is produced by a second process. Here, a cover layer of polyurethane is applied on one side of the composite part. This additional polyurethane top layer creates the necessary surface quality in Class-A.

In this composite, the final polyurethane topcoat does not contribute to the load bearing capacity of the component. In this respect, it is advantageous if the layer thickness is kept as low as possible. For this purpose, preferably material thicknesses between 0.5 and 3 mm, advantageously below 1.5 mm used.

Preferably, such composite components find their use as part of a vehicle body, such. B. as part of the vehicle roof or the hood.

The common manufacturing methods of the prior art are not suitable for the advantageous embodiment. In particular, the honeycomb width when using a paper honeycomb as an intermediate layer leads to a problem with respect to the surface of the cover layer. In the conventional manufacturing process, a first glass fiber mat is inserted into a tool, whereupon a corresponding polyurethane compound is introduced. Subsequently, the paper honeycomb is placed and in the following the second glass fiber layer with the corresponding application of the second polyurethane preparation. Although, after closing the tool and curing the polyurethane composition, the honeycomb structure can not be recognized is, then the honeycomb structure on the surface is visible in subsequent polyurethane coating of the surface. In this respect, therefore, no Class A surface can be achieved.

Therefore, according to the invention, a new method for the production according to the composite component is used. From the basic concept, this corresponds to the known method of production, but in this case the fiber fabric, in particular the glass fiber fabric, is stretched next to the tool where it is already sprayed with the polyurethane preparation. This impregnates the fiberglass fabric and spreads it flat. The corresponding first polyurethane-impregnated glass fiber fabric is inserted into the tool. As a further step, as in the conventional method, the paper honeycomb layer is placed on the polyurethane-impregnated glass fiber layer. In the following, the first step is repeated insofar as a second fiber fabric or glass fiber fabric is clamped and this is sprayed with a corresponding polyurethane preparation. Likewise, the polyurethane completely soaks through the fiberglass fabric. The corresponding glass fiber fabric is then placed again in the tool on the paper honeycomb layer. As in the usual process now follows the closing of the tool with the curing of the polyurethane at elevated pressure and an elevated temperature. This first process creates the load-bearing layer sequence.

In a second process with a second tool, the corresponding polyurethane surface is produced. For this purpose, the tool has a cavity which is formed by a defined gap between the previously produced bearing layer sequence and the shape of the second tool half. In a method known from the injection molding process, after the second tool has been closed, the cavity is filled with a corresponding polyurethane preparation. The polyurethane cures at elevated pressure and temperature, as in the previous process. The inventive manufacturing process has succeeded in achieving a perfect Class A surface.

Alternatively, the step of filling with a polyurethane preparation but also before the step of closing the second tool can be done. For this purpose, a polyurethane preparation is applied to the at least largely cured bearing layer sequence and subsequently closed the second tool.

Based on the advantageous manufacturing method, it is also possible not to spray the two fiber-reinforced layers sequentially with the polyurethane preparation sequentially, but rather at the same time, the order of introduction into the tool remains unchanged.

As explained above, the inserted paper honeycomb layer is usually pressed flat in the edge region. However, it is necessary for the supporting function that the paper honeycomb layer largely retains its shape. Because only by the height of the paper honeycomb layer, the corresponding bending stiffness of the composite is achieved. Thus, it is obvious that the paper honeycomb layer in the majority of the composite component must retain their shape, which is made possible by a corresponding method.

It was executed that in the second process a second tool is required. On the one hand, this can consist of an independent second tool, wherein the bearing layer sequence is removed from the first tool and inserted into the second tool in alternation from the first process. However, it is also possible for the purpose of generating the second tool to use the tool half of the first tool for this purpose. In this case, the tool upper half of the first tool is removed and placed the tool half of the second tool. Consequently, the step of removing and inserting the load-bearing layer sequence is also eliminated.

Advantageously, the polyurethane preparation is filled into the closed mold in the manner of the injection molding process for the production of the cover layer. However, it is also conceivable to apply the polyurethane composition to the load-bearing layer sequence in the opened second tool and subsequently to close the tool so as to produce the corresponding uniform distribution of the polyurethane preparation.

The construction of the inventive composite component of polyurethane sandwich materials with Class A cover layer is sketchily shown in the figures. Likewise, the manufacturing process is shown schematically.

Show it:

1 schematically the layer structure of the inventive composite component;

2 schematically the second process step for producing the cover layer of the composite component;

3 schematically the first process step for producing the load-bearing layer sequence.

in the 1 is the load-bearing layer sequence 06 to recognize which from a glass fiber reinforced polyurethane layer 05 , an intermediate layer as a paper honeycomb 04 and another glass fiber reinforced polyurethane layer 03 consists. Finally, the polyurethane covering layer is located on the composite component according to the invention 02 ,

The 2 schematically outlines the second manufacturing process, in which in the type of injection molding process on the supporting layer 06 the polyurethane preparation through an opening 17 into the cavity 16 of the second tool 13 is filled. The cavity 16 is formed by the lower tool part 14 with superimposed bearing layer sequence 06 as a gap to the second tool half 15 ,

In 3 sketchy the first process is shown. This is on the clamped glass fiber mats 08a . 08b the polyurethane preparation 07a . 07b applied. The polyurethane-impregnated first glass fiber mat is prepared accordingly 03 on the lower tool part 11 of the first tool 10 hung up. The following is the paper honeycomb 04 placed as an intermediate layer and finally the second polyurethane-impregnated glass fiber layer 05 , By closing the tool 10 with pressing on the upper part of the tool 12 and applying an elevated temperature becomes the polyurethane 07a . 07b hardened.

Claims (15)

Method for producing a composite part ( 01 ), characterized in that the production takes place in the following process steps: (Aa) clamping a first fiber fabric ( 08a ) next to a tool required for the first process ( 10 ); (Ab) spraying the first fibrous tissue ( 08a ) with a polyurethane preparation ( 07a ); (Ac) Loading the polyurethane ( 07a ) -saturated first fibrous tissue ( 08a ) into the tool ( 10 ); (Ad) Inserting a paper honeycomb layer ( 04 ) into the mold on the first polyurethane ( 07a ) -saturated fiber fabrics ( 08a ); (Ae) stretching a second fiber fabric ( 08b ); (Af) spraying the second fibrous tissue ( 08b ) with a polyurethane preparation ( 07b ); (Ag) Loading the polyurethane ( 07b ) soaked second fiber web ( 08b ) into the tool ( 10 ) on the paper honeycomb layer ( 04 ); (Ah) closing the tool ( 10 ); (Ai) at least substantial curing of the polyurethane ( 07 ) at elevated pressure and / or elevated temperature to form a load-bearing layer sequence ( 06 ); (Aj) removal of the load-bearing layer sequence ( 06 ) from the first tool ( 10 ); either (Ba) inserting the bearing layer sequence ( 06 ) from the first process step into a second tool ( 13 ) for the second process step; (Bb) closing the second tool ( 13 ), wherein in the mold cavity of the second tool ( 13 ) a defined gap on one side of the second tool ( 13 ) and thus a cavity ( 16 ) forms; (Bc) filling the cavity ( 16 ) with a polyurethane preparation; or that the step (Bc) of filling with a polyurethane preparation prior to the step (Bb) of closing the second tool ( 13 ) is carried out as a polyurethane preparation on the at least largely cured bearing layer sequence ( 06 ) and subsequently the second tool ( 13 ) is closed; (Bd) Curing of the polyurethane ( 02 ) at elevated pressure and / or temperature, forming a topcoat of Class A quality; (Be) removal of the finished composite part ( 01 ). A method according to claim 1, characterized in that the steps (Ae) and (Af) take place parallel to (Aa) and (Ab). A method according to claim 1 or 2, characterized in that when closing the tool ( 10 ) in step (Ah) the fibrous tissue ( 08a . 08b ) is pressed flat, wherein in the edge region and / or in functional areas the paper honeycomb layer ( 04 ) is also pressed flat, the overwhelming part of the paper honeycomb layer ( 04 ) retains its shape. Method according to one of claims 1 to 3, characterized in that for the purpose of generating the mold cavity in the second tool ( 13 ) for the second process, the tool shell ( 12 ) of the first tool ( 10 ) against a second tool shell ( 15 ), and wherein the first tool lower part ( 11 ) at the same time the second tool lower part ( 14 ). Composite component ( 01 ) produced by a process according to the preceding claims 1 to 4, from PU sandwich materials with Class A covering layer ( 02 ), consisting of a load-bearing layer sequence ( 06 ) with a fiber-reinforced polyurethane layer ( 03 ) high strength, a paper honeycomb layer ( 04 ) and a fiber-reinforced polyurethane layer ( 05 ) of high strength, characterized in that on at least one side of the composite part a cover layer ( 02 ) is made of polyurethane, wherein the polyurethane cover layer ( 02 ) Has Class A quality. Composite component ( 01 ) according to claim 5, characterized in that the paper honeycomb layer ( 04 ) has a density of less than 0.1 g / cm ³ . Composite component according to claim 6, characterized in that the inside width of each honeycomb over 2 mm, in particular over 4 mm. Composite component ( 01 ) according to one of claims 5 to 7, characterized in that the fibers in the fiber-reinforced polyurethane layers ( 03 . 05 ) Are glass fibers. Composite part according to claim 8, characterized in that the glass fiber content in the two glass fiber reinforced polyurethane layers ( 03 . 05 ) is above 30%, in particular above 55%. Composite component ( 01 ) according to one of claims 5 to 9, characterized in that the paper honeycomb layer ( 04 ) over the entire extent of the component between the two fiber-reinforced polyurethane layers ( 03 . 05 ) is available. Composite component ( 01 ) according to claim 10, characterized in that the paper honeycomb layer ( 04 ) is permanently compressed in the peripheral region and / or in functional areas. Composite component ( 01 ) according to one of claims 5 to 11, characterized in that the paper honeycomb layer ( 04 ) has a thickness of between 2 mm and 20 mm, in particular a thickness of more than 5 mm. Composite component ( 01 ) according to one of claims 5 to 12, characterized in that the strength of the composite component ( 01 ) is between 5 mm and 20 mm. Composite component ( 01 ) according to one of claims 5 to 13, characterized in that the cover layer ( 02 ) has a thickness between 0.5 mm and 3 mm, in particular a thickness of less than 1.5 mm. Composite component ( 01 ) according to one of claims 5 to 14, characterized in that the composite component ( 01 ) Is part of a vehicle body.

Images