NL1029469C2 - Producing shaped composite material articles, useful as construction elements, by bonding assembly of metal and thermoplastic layers using heated forming tool - Google Patents

Abstract

A stack of at least one metal layer (1) and at least one thermoplastic polymer layer (2') is heated to a first temperature and then shaped using a forming tool (7a, 7b) heated to a second temperature so that the metal and thermoplastic layers become bonded together. A method for producing a shaped article from a composite material comprising at least one metal layer and at least one thermoplastic polymer layer comprises the following steps: (A) forming a stack of at least one metal layer and at least one thermoplastic polymer layer; (B) heating the resulting assembly to a first temperature; and (C) shaping the assembly using a forming tool heated to a second temperature so that the metal and thermoplastic layers become bonded together. Independent claims are also included for the process apparatus, a partly consolidated laminate comprising at least one metal layer and at least one thermoplastic polymer layer and the use of this laminate for producing a shaped composite material article.

Description

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Method for manufacturing a molded part from a composite material

The invention relates to a method for manufacturing a molded part from a composite material, which comprises at least one metal layer and a thermoplastic plastic layer. The invention also relates to a device for manufacturing the molded part.

A method for manufacturing a molded part from a composite material 10 is known from EP-A-547664. Herein a molded part is obtained from an aluminum-polypropylene-aluminum laminate by pre-heating this laminate to a well-defined temperature and then forming it into a mold tool to the desired shape. In the known method, therefore, use is made of a material that has already been assembled prior to the production of the molded part. Such a generally plate-shaped semi-finished product is also referred to in the art by the general term plastic metal laminate. The known plastic metal laminate can be obtained by connecting two metal layers from, for example, aluminum, and an intermediate plastic layer from, for example, polypropylene by heating under pressure, and then cooling them to the storage temperature. A variant known in the art under the name fiber metal laminate is obtained in a similar manner, but the plastic layer is provided with fiber reinforcement, therefore consists of composite material.

In order to be able to obtain a molded part with good mechanical properties from the composite material described above, the use of plastic metal laminate considered necessary in the manufacture of the molded part.

For good mechanical properties, among other things, it is indeed desirable that the different layers of the composite material are mutually well connected in the molded part, in other words form a consolidated whole. This good bonding in the molded part is ensured by establishing the bonding between the different layers prior to the actual shaping, namely by consolidating the layers under pressure in the manufacture of the laminate, and subsequently using this laminate in the design. The above applies a fortiori to fiber metal laminates, in which, in addition to the desired consolidation of the 1029469-2 different layers, good impregnation of the reinforcement fibers with the thermoplastic plastic is also important.

The known method has the drawback that it is time-consuming, wherein the different steps of bonding the layers or of forming into a molded part are carried out at different locations with different equipment. Furthermore, it has proved difficult to obtain molded parts with the known method which exhibit good form stability.

The present invention has for its object to provide a simpler method for manufacturing a molded part from composite material, wherein the molded part exhibits good mechanical properties, and in particular mold stability.

To this end, the method according to the invention for manufacturing a molded part from a composite material is characterized in that the method comprises the steps of: a) stacking at least one metal layer and at least one thermoplastic plastic layer; B) bringing the assembly thus formed to a first temperature; c) deforming the assembly using a shaping tool brought to a second temperature, the at least one metal layer and the at least one thermoplastic plastic layer being interconnected.

According to the present invention, it is proposed in step c) to both deform and connect the various layers of the composite material under the influence of the shaping tool. It has been found that with this a molded part can be obtained with complex shape, wherein undesired effects such as, for example, cracking in the layers as a result of the strong distortion are reduced or avoided. The assembly thus comprises, prior to step c), a number of mutually substantially non-bonded layers. According to the invention, however, it is possible that after performing steps a) and b) the layers of the assembly are at least partially connected to each other. However, this bond does not correspond to the bond between the layers desired in the molding. In a preferred embodiment of the method according to the invention, the bond between the different layers in the assembly formed in steps a) and b) is such that the interlaminar shear strength (Interlaminar Shear Strength, ILSS) measured according to ASTM D2344 thereof is at most 60% of the ILSS of the fully consolidated laminate, more preferably at most 40%, even more preferably at most 20% By simultaneously joining and deforming the assembly of at least one metal layer and a thermoplastic plastic layer provides a simple method for manufacturing such a deformed assembly.The number of steps is limited, while moving between different machines is not necessary.

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When in this application there is a first and a second temperature, this means an average temperature. It will be clear that when, for example, reference is made to bringing the assembly thus formed to a first temperature in step b), this means that the assembly has assumed on average the first temperature, whereby local variations may occur. The same applies to step c) wherein the shaping tool is at a second temperature. Here too it is possible that a different temperature prevails locally, which, although not much different from the average second temperature.

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A possible embodiment of the method is to stack the right number of layers on top of each other in the right order, and to bring this stack to the first temperature. The height of the first temperature depends inter alia on the type of thermoplastic plastic, on the type of metal, but also, for example, on the shape of the molded part to be produced, and can vary from temperatures below room temperature to hundreds of ° C. A suitable method for bringing to the first temperature is, for example, to heat the stack with the aid of contact heat by placing it between hot plates. It is also possible to heat the assembly by means of radiant heat, for example infrared (IR).

Once heated, the assembly in step c) is placed, for example, in a press comprising a mold with the desired shape of the product to be manufactured. The mold here has a second temperature which is usually, but not necessarily, lower than the first temperature. By closing the press, the mold parts are pressed onto each other while the stack is deformed, whereby the at least one thermoplastic 10294 69-s

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4 plastic layer is connected to the at least one metal layer. Another possible embodiment is to stack the correct number of layers on top of each other in the correct order, and to bring this stack to the first temperature by placing the stack in a mold heated to the first temperature. The mold is then closed and cooled to the second temperature.

In a preferred embodiment of the method according to the invention, an adhesive layer is present at least between one metal layer and one thermoplastic plastic layer. Such an adhesive layer can be applied separately between the relevant layers, for example by means of a suitable coating device. Both adhesives based on thermosetting resins and adhesives based on thermoplastic plastics are in principle suitable. For example, it is possible that the thermoplastic plastic itself serves as an adhesive. However, most thermoplastic plastics do not adhere sufficiently to metal, and thus it is advantageous if a separate thermoreversible adhesive layer is used. Thermoreversible adhesives are known per se to the person skilled in the art and have the property that after being brought to temperature they can be melted at least once more, this in contrast to a thermosetting glue which after curing thereof is no longer meltable. Extremely suitable thermoreversible adhesives are commercially available, for example from CCT B.V. under the trade names AD 20 Adhesive R12 (based on polyester) and AD Adhesive R23 (based on modified polypropylene). In a preferred embodiment of the method, at least a portion of the surface of at least one metal layer is provided with a thermoreversible glue layer, so that the metal layer in question is at least partially already 'wetted' with the glue. This facilitates the positioning of the adhesive layer in the assembly. In another preferred embodiment, at least a portion of the surface of at least one thermoplastic plastic layer is provided with a thermoreversible adhesive layer. Suitable techniques for applying the thermoreversible glue to the metal layer include lamination, spraying, dipping, roller coating, strip coating and dipping. Suitable thermoreversible adhesives 30 are compatible with the metal and / or the thermoplastic plastic, and are furthermore fusible at least once. The glue is preferably chosen such that the glue layer applied as a result of the coating process is substantially dry (does not exhibit so-called "tack"), so that the pre-coated layers can easily be stacked and / or rolled up. The thermoreversible glue is pre-applied to the at least one 10294 69-

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If the metal layer and / or the at least one plastic layer are provided, the thickness is advantageously between 1 and 100 micrometres, more preferably between 5 and 30 micrometres. In another preferred embodiment, only in step a) is a thermoreversible adhesive film applied between at least one metal layer and a thermoplastic plastic layer.

If the thermoreversible glue is used as a separate film in the method according to the invention, the thickness is preferably between 1-100 micrometres, more preferably between 20 and 80 micrometres.

According to an embodiment of the invention, an assembly can be formed in step a) which essentially consists of a first and a second metal layer between which a thermoplastic plastic layer is situated. Thus, with the method, a sandwich can be obtained which consists of two outer metal layers, between which a thermoplastic plastic layer is included. If desired, this plastic layer can be applied in the form of a foam, but there is, however, the risk that the foam structure is destroyed during the shaping and connecting step. Also in these variants of the method according to the invention, a thermoreversible adhesive layer is preferably applied between the thermoplastic plastic layer and the second metal layer in step a), but more preferably this thermoreversible adhesive layer is applied on the surface of the second metal layer in advance.

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The at least one metal layer advantageously comprises a metal plate, or a continuously supplied metal strip and / or metal web. Usually, in the method according to the invention, the metal layer, at least at least the surface thereof to be connected to the thermoplastic plastic layer, will be pretreated in order to protect the metal, for example against corrosion, and to improve the adhesive capacity. Examples of such pretreatments include degreasing, chromatography, anodizing and applying a conversion coating, applying a primer and / or a normal conversion coating. A suitable agent of the latter type is, for example, the CCT B.V. (Cr (VI) containing or Cr (VI) free product available in the Netherlands under the trade name PrimeCoat. The nature of the metal is not critical to the process. Preferably the metal is selected from aluminum or (lightweight) alloys thereof , made of stainless steel, cold-formed steel, galvanized steel, magnesium, lithium, titanium, copper and / or alloys thereof Aluminum alloys are particularly preferred The thickness of the metal layer according to the invention is advantageously in accordance with the invention. range of 0.05 to 2 millimeters, more preferably between 0.1 and 1.2 mm, most preferably between 0.2 and 0.6 mm.

Although it is customary according to the invention to use the same metal in the at least one metal layer, it is advantageous to characterize the method in that in step a) an assembly is formed which comprises a first and at least a second metal layer, the second metal being different from the first. For example, it is advantageous if the molded article is used in a corrosive environment where at the same time a low weight is desired, the outer layers of the assembly can be made of stainless steel, and the inner layers can be made of a lightweight metal, for example aluminum. . An additional example of the method according to the invention is that it offers great flexibility because when assembling the assembly one is not bound to commercially available laminates.

15

Examples of thermoplastic plastics suitable for the process according to the invention are polyamides, polyimides, polyether sulfones, polyether ether ketone, polyurethanes, polyethylene, polypropylene, polyphenylene sulfides (PPS), polyamide-imides, acrylonitrile-butadiene-styrene (ABS), styrene / maleic anhydride (SMA) , Polycarbonate, polyphenylene oxide blend (PPO), thermoplastic polyesters such as polyethylene terephthalate, polybutylene terephthalate, as well as blends and copolymers of one or more of the aforementioned polymers. The method according to the invention is preferably characterized in that at least one of the thermoplastic plastic layers comprises a fiber-reinforced plastic. Suitable reinforcement fibers are, for example, glass fibers, carbon fibers, metal fibers, stretched thermoplastic synthetic fibers, such as, for example, aramid fibers and ultra-high molecular weight polyethylene or polypropylene fibers, as well as natural fibers such as, for example, flax, wood and hemp fibers. In another embodiment, the thermoplastic plastic layer comprises fabrics of pre-oriented thermoplastic polymers, such as, for example, polypropylene. Such products are commercially available from, among others, BP / Amoco under the trade name Curv, and from Lanckhorst under the trade name Pure. The thickness of the at least one thermoplastic plastic layer is preferably in the range of 0.1 to 10 mm, more preferably between 0.5 - 5.0 mm, most preferably between 0.2 - 3.0 mm. Although it is customary according to the invention to use the same thermoplastic plastic in the at least one thermoplastic plastic layer, it is advantageous to characterize the method in that an assembly is formed in step a) comprising a first and at least a second thermoplastic plastic layer wherein the second plastic differs from the first.

In a special embodiment of the method according to the invention, an assembly is formed in step a) which comprises at least one fiber layer. Such a dry fiber layer (not impregnated with a thermosetting or thermoplastic plastic) or partially impregnated fiber layer (semi-preg) has the advantage that it is relatively easy to deform. Moreover, its application increases the flexibility of the method. By deforming the at least one fiber layer in step c) together with the other plastic layers, a well-consolidated molded article is surprisingly obtained, wherein the wetting (impregnation) of the fibers with the plastic takes place during the forming process. It is also possible in such an embodiment! apply so-called commingled and / or intermingled rovings. Such rovings include a reinforcing fiber and a thermoplastic fiber in fiber form. It is also possible to use an already consolidated fiber-reinforced thermoplastic plate for the plastic layer. A suitable example of such a material is, for example, a consolidated thermoplastic polyurethane plate, which is reinforced with a fabric, and has a thickness between approximately 0.5 and 2 mm.

The fiber layer and / or the fiber-reinforced plastic layer preferably comprises substantially continuous fibers that extend in two substantially orthogonal directions (so-called isotropic fabric). In another preferred embodiment, the fiber layer and / or the fiber-reinforced plastic layer comprises substantially continuous fibers that extend substantially in one direction (so-called UD fabric). The specific choice of the type of fabric depends, among other things, on the desired mechanical properties and on the deformability of the fabric. The chosen embodiment of the method according to the invention can also be of importance here.

There are different variants for the implementation of partial aspects of the process steps. To be able to set the first temperature, the one or more metal layers and (fiber-reinforced) plastic layers can be preheated in a 1029439?

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8 separate oven. It is advantageous here to choose the first temperature higher than the glass transition temperature of the thermoplastic plastic or to choose higher than the lowest glass transition temperature in case several thermoplastic plastics are used. More preferably, the first temperature is higher than the melting temperature of the thermoplastic plastic or higher than the lowest melting temperature in case multiple thermoplastic plastics are used. If a thermoreversible glue is used, the melting temperature of the glue is also of particular importance. It has been found that the best results are achieved when the first temperature is higher than the melting temperature of the thermoreversible glue. In a further improved method according to the invention, the second temperature is chosen such that it is lower than the melting temperature of the thermoreversible glue. The melting temperature (or the melting temperature range) under which the thermoreversible glue is re-hardened after heating and thus under which the actual bonding is effected is known to the person skilled in the art, and can for instance be indicated by the supplier of the glue in question.

After preheating in step b), the stack is then transferred to the relevant forming device, which comprises at least one forming tool, and is at least partially at the second temperature. To facilitate the transfer, the stack may optionally be included in a clamping frame. An additional advantage of the use of a clamping frame or so-called "blank holder" is that this allows the metal to be deformed plastically immediately during shaping where the yield stress is achieved through deformation. This prevents the still stiff metal from sliding, springing up and / or springing up during closing of the mold. The clamping frame usually runs along the peripheral edges of the stack. Thus, according to the invention, the preheated assembly can for instance be mounted in an unheated shaping tool, which is located at room temperature or even below, and deformed and cooled by means of its closure. It is also possible to use a shaping tool with controlled heating. For example, in a suitable method, the assembly is preheated to 180 ° C and then transferred to a shaping tool that has been brought to a temperature of about 120 ° C. By closing it, the stack is then deformed and consolidated in one processing step, while furthermore the layers are mutually adhered. It will be clear that it is also possible to pre-heat the individual layers of the stack, and only then to establish the stack.

In another embodiment, the stack is heated by contact with a heated forming tool such as a press. The press is provided with a mold which is at least provided with cooling means. First, the stack, if desired under pressure, is preheated in the mold to the first temperature, after which it is cooled to the second temperature under pressure, optionally with further closure of the mold.

In yet another embodiment, the stack, if desired provided with a clamping frame, is placed between the mold halves of a press. A heating device, for example a number of infrared heaters, is then brought between the stack and at least one mold half to pre-heat the stack. After this pre-heating step (step b)) the heating device is removed from between the mold halves, after which the mold is closed to shape the stack and to consolidate.

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For forming into the desired molded part, the stacking can be done with the aid of a male mold mold made of metal or rubber (a rubber mold does not have to fit precisely here because it is generally pressed into the female mold relatively easily); be printed in a female mold. This distortion can happen without that a clamping frame is applied. During deformation by stretching, the edges I of the stack are at least partially clamped by the clamping frame and / or by mold parts provided for this purpose. Another possible deformation step is diaphragm shapes, wherein the stack is surrounded by foil layers, which are then clamped along the edges. This has the advantage that the stacking itself can shift relatively easily during shaping. The shaping is done by lowering or increasing the air pressure on one side of the stack. A variant is to use a liquid instead of air. The foil (the "diaphragm") can be made of plastic. It is also possible to use a thin metal foil for this.

A preferred method is performed according to the so-called roll-forming process. Hereby the at least one metal layer in the form of a continuous metal plate and / or band and / or strip, and the at least one thermoplastic plastic layer in the form of a continuous plastic plate and / or foil from stock rolls or reels supplied and stacked almost continuously at the first temperature, after which they are deformed with the aid of at least one forming roller brought to the second temperature. If desired, a plurality of rollers are used which may optionally have a different temperature than the second temperature.

By stacking at the first temperature is meant that the formed stack reaches approximately the first temperature at least somewhere in the roll-form line. In this preferred method, the throughput speed is preferably substantially constant and the at least one metal strip and / or the at least one thermoplastic plastic layer is preferably provided with thermoreversible glue. The stack is bent or otherwise deformed during movement by the forming rollers. In this case, the shape of each roller in the line can be adjusted, if desired, to allow for gradual deformation during the passage of the line, the temperature for instance always decreasing until it reaches approximately the second temperature. If desired, the layers of the stack can be supplied from an individual stock, or continuously from stock rolls or reels. As previously stated, for thermoplastic plastics that exhibit low adhesion to pretreated metal, a thermoreversible adhesive layer is advantageously placed between the thermoplastic plastic layer and the metal layer in step a). In this embodiment of the method according to the invention, the thermoreversible glue is applied as a separate layer between the metal layer and the thermoplastic plastic layer. As the temperature rises, the thermoreversible glue will adhere to both the surface of the metal layer and the surface of the thermoplastic plastic layer and will stick to it on cooling. In another more preferred embodiment, the thermoreversible adhesive layer 25 is pre-applied to the surface of the metal layer. The thermoplastic plastic layer is advantageously reinforced with fibers in this embodiment. Thermoplastic composite layers in the stack ensure increased rigidity of the stack when the line is run through. It will be clear that variants of the roll-forming process are also the object of the method according to the invention. For example, it is possible to advance the stack after step a) through a number of molds ("pultrusion"), which molds are adjusted to different temperatures if desired. It is essential for the method according to the invention that in the pultrusion line the stack must be brought to a first temperature, and that the final shaping and consolidation step must take place in a mold which is set at substantially the second temperature. . The pultrusion method is distinguished from the roll-forming method in that the molds surround the stack almost completely.

The invention is explained below with reference to the accompanying figures, in which:

FIG. 1 is a schematic representation of the starting materials as used in the method according to the invention;

FIG. 2 schematically shows the method steps of an embodiment of the invention; FIG. 3 schematically shows the method steps of another embodiment of the invention;

FIG. 4 schematically shows the method steps of yet another embodiment of the invention;

FIG. 5 schematically shows the method steps of yet another embodiment of the invention;

FIG. 6 schematically shows the method steps of yet another embodiment of the invention.

Figure 1a shows a stack 10, which comprises two outer metal plates 1, which are provided on the opposite sides with a thermoreversible adhesive layer 3. A fiber-reinforced plastic layer 2 is arranged between the plates 1. Furthermore, the metal plates 1 can be provided with a pre-treatment layer 5, which can comprise a conversion layer or a primer, and with a decorative and / or functional coating layer 4. Figure 1b shows a first variant in which a stack 10a of two with a thermoreversible is applied glue layer 3 'coated metal layers 1, and a fiber-reinforced plastic layer 2. Figure 1c shows a second variant in which a stack 10b of two metal layers 1, a fiber-reinforced plastic layer 2 is applied, and two thermoreversible glue films 3' arranged on either side thereof. Figure 1d shows a third variant in which a stack 10c is applied of two metal layers 1, provided on the outside with a decorative and / or functional coating layer 4, and on the inside with a pretreatment layer 5, and a fiber-reinforced plastic layer 2.

Figure 2a schematically shows a pre-heating oven 6, in which a stack 10 as described above is pre-heated for a suitable time to the first temperature. The stack 10 thus preheated is then placed in a mold 7, as indicated in Figure 2b. Mold 7 comprises at least one female mold part 7a and a male mold part 7b, which together define the deformation to be applied, in the case shown a recess. Mal 7 is in a suitable! 5 deforming tool such as, for example, a press (not shown). At least one mold part 7 and / or the press is optionally provided with a heating device, which is set to the second temperature. This temperature setting of the forming tool can be understood to mean that the press and / or the mold parts and / or only one mold part is set to the second temperature. For example, it is possible that only the female mold part 7a is brought to the second temperature.

The mold 7 is then closed by closing the press and kept under pressure for a short time, while simultaneously consolidating and bonding the layers of the assembly 10 (Figure 2c). The molded part 10 "thus formed is approximately at the second temperature, and can, if desired, be removed from the mold 7 and further cooled to the final molded part 10" (Fig. 2d).

In a preferred embodiment of the method, only a portion of the starting materials of the assembly are preheated or the starting materials are preheated at different temperatures. With reference to Fig. 3a, for example, a fiber-reinforced thermoplastic plastic 2 is preheated in a suitable preheating oven 6. A subassembly, in Fig. 3b consisting of two metal strips 1 with pretreatment layer 5, thermoreversible adhesive layer 3 'and decorative or functional coating 4, is already present in the mold 7. The preheated fiber-reinforced thermoplastic plastic layer 2 is then applied between the metal strips in the mold 7, as can be seen in figure 3c, wherein these strips 1 will at least partially assume the first temperature. The mold! is here at the second temperature. The further sub-steps in this embodiment are as indicated above.

In yet another embodiment, the pre-heating takes place in the deforming tool 7 itself. With reference to figure 4, the stack 10 is preheated by arranging it, at least partially included in a clamping frame 13, between the mold parts 7a, 7b of a mold 7. At least one mold part 7 and / or the press is optionally provided with a (schematically represented) heating device 14, 1029469-

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13 which is first set to the first temperature (Figure 4a). After sufficient preheating, the mold 7 is cooled by adjusting the heating device 14 to the second temperature and by closing the press, the mold 7 is closed and kept under pressure for a short time, while at the same time consolidation and adhesion of the layers of the assembly 10 takes place (figure 2b). In this variant, during pre-heating and / or pressing, the assembly is clampingly received in the clamping frame 13. As a result, on the one hand, the assembly is held together so that easy and, if desired, automatic transport of the assembly is made possible, and on the other hand, that the assembly can be tensioned be held during preheating and / or shaping, whereby the metal also deforms almost immediately during the closing of the molds.

In yet another preferred embodiment of the method, as shown in Figure 5, at least one metal layer in the form of a continuous metal plate 1 "and at least one thermoplastic plastic layer in the form of a continuous plastic plate 2" are continuously supplied in the direction of movement 20 from roll-off mechanisms or reels 15 by means of a pulling device (not shown). The pulling device can for instance comprise a heated conveyor belt. The metal plate 1 is preferably already coated with a thermoreversible adhesive layer 3, decorative or functional coating 4, and pre-treatment layer 5. The layers 1 "and 2" are brought together via guide rollers 16 in a substantially unconsolidated stack 10 and subsequently preheated in furnace device 6 at the first temperature, whereafter the stack 10 is deformed by means of at least one form roller 17 brought to the second temperature into a corrugated profile 18 as shown in figure 5a, and / or by means of at least one mold brought to the second temperature (7a, 7b) is distorted. In the latter variant, it is necessary to carry out the method semi-continuously, whereby the line speed is temporarily interrupted for pressing. It is also possible to cause the deforming tool 7 to move along in the direction of movement 20 during shaping. If desired, the device is also provided with a sawing or cutting machine 19 for bringing the formed profiles to the desired length. The indicated direction 21 here corresponds to the cutting or sawing direction.

1029469- * 1 14

In yet another preferred embodiment, the stack 10, formed as described above, is preheated in a furnace device 6 to the first temperature, whereafter the stack 10 is deformed or deformed by means of a roll forming machine 22, the wheels 23 of which are at least partially brought to the second temperature. bent to a profile 18 as shown in figure 6. If desired, the device is again provided with a sawing or cutting machine 19 for bringing the formed profiles to the desired length.

The invention will be further explained below with reference to the following examples.

Example 1

Aluminum plates (2024-T3) with a thickness of approximately 0.3 mm were pre-treated by degreasing them and providing them with a so-called no-conversion conversion coating (Primecoat A454 from the company CCT B.V. in the Netherlands). Subsequently, the pretreated plates were provided on a surface with a 15 micron thick thermoreversible polyester adhesive (AD Adhesive R-12, also available from the company CCT B.V. in the Netherlands) with the aid of coating rollers. The thermoplastic plastic layer used was a consolidated sheet of thermoplastic polyurethane reinforced with glass fiber cloth (twill weave 2 / 2,290 g / m2) with a total thickness of approximately 1.0 mm. The aluminum sheets and the thermoplastic plastic layer were stacked on top of each other to form a sandwich and preheated to an initial temperature of about 230 ° C in an infrared oven, and then transferred to a press.

The press had a lower pressing plate with a female mold made of aluminum (single curved rib) and a rubber male mold mounted on an upper pressing plate. The press was at room temperature (the second temperature). The preheated sandwich was placed on the lower pressing plate. The upper press plate was lowered to press the stacked plates and layer into the female mold. The deformed assembly was allowed to cool in the mold while the pressure was maintained, after which the molded part was removed from the mold.

Very good adhesion between the layers was obtained.

Example 2

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A sandwich of outer plates of aluminum alloy 3005 H14 with a thickness of approximately 0.6 mm, a middle sheet of pre-oriented polypropylene fibers with a thickness of approximately 1 mm and on either side thereof a glue sheet with a thickness of approximately 35 micrometres of modified polypropylene polymer was stacks 5. A press with a similar structure as in Example 1, except that the male mold was made of aluminum, was preheated to a first temperature of 170 ° C, after which the sandwich was placed therein and the edges of the sandwich clamped between the pressing plates. The upper press plate was lowered at high speed to deform the sandwich in the female mold. The deformed sandwich was allowed to cool in the mold by adjusting the heater present in the mold to substantially room temperature (the second temperature) while maintaining the pressure.

Example 3

The starting materials used were an approximately 0.4 mm thick non-consolidated polypropylene strip reinforced with unidirectional glass fibers (comingled roving), which was continuously unwound from a supply roll, as well as an approximately 0.5 mm thick aluminum foil (AA5050 H26) coated on a side with an adhesive layer of AD Adhesive R23 (approximately 10 micrometres thick) (based on modified polypropylene polymer), which was unwound from a supply roll at the same speed. Both strips of material were passed through an oven in which the metal strip was heated to approximately 200 ° C and the strip of thermoplastic material to approximately 180 ° C. The raw materials thus preheated were positioned on top of each other at a first temperature of about 190 ° C, and continuously passed through a set of shaping rollers and cooling rollers set to room temperature to provide simple bending. After cooling, the thus formed profile was cut to size.

Example 4

Two stainless steel plates (from 4016) with a thickness of approximately 0.2 mm were pre-treated by degreasing and providing a so-called no-chromium-free conversion coating (Primecoat NC from the firm CCT B.V. in the Netherlands). The pre-treated plates were not provided with an adhesive layer. The thermoplastic plastic layer used was a consolidated sheet of thermoplastic polyphenylene sulfide 1029469-16 (PPS) reinforced with fiberglass cloth (twill weave 2 / 2,290 g / m2) with a total thickness of approximately 1.0 mm. The steel plates and the thermoplastic plastic layer were stacked on top of each other to form a sandwich and preheated to an initial temperature of about 300 ° C in an infrared oven, and then transferred to a press. The 5 press was provided with two press plates with mold half, the two mold halves both being made of metal. The press was at a temperature of approximately 120 ° C. The preheated sandwich was placed on the lower pressing plate. The upper press plate was lowered to press the stacked plates and layer into the female mold. The deformed assembly was allowed to cool in the mold while the pressure was maintained, after which the molded part was removed from the mold at a temperature of about 120 ° C. Very good adhesion between the layers was obtained.

In addition to the good adhesion and consolidation of the various layers, the moldings obtained in the examples described above were found to retain their shape stability for a long time. They also showed a good surface finish. By being able to easily combine metal layers with reinforced plastic layers, a great freedom of choice with regard to the final product properties such as rigidity, tensile strength, surface finish, weight and price is obtained.

The molded parts obtained with the method according to the invention can be used as a lightweight structural element in industrial applications, such as, for example, in structures, buildings, vehicles, ships, wherein the decorative and / or protective properties of a metal outer surface are desired. A great advantage of the method according to the invention is that such molded parts can be manufactured in a simple manner, wherein the molded part has good mechanical properties, and in particular mold stability.

1029469-

Claims (23)

A method for manufacturing a molded part from a composite material, comprising at least one metal layer and a thermoplastic plastic layer, which method comprises the steps of a) stacking at least one metal layer and at least one thermoplastic plastic layer; b) bringing the assembly thus formed to a first temperature; C) deforming the assembly using a shaping tool brought to a second temperature, the at least one metal layer and the at least one thermoplastic plastic layer being interconnected. 2. Method as claimed in claim 1, characterized in that an adhesive layer is present at least between one metal layer and one thermoplastic plastic layer. Method according to claim 2, characterized in that the adhesive layer is a thermoreversible adhesive layer. 4. Method as claimed in any of the foregoing claims, characterized in that at least a part of the surface of at least one metal layer is provided with a thermoreversible glue layer. 5. Method as claimed in any of the foregoing claims, characterized in that at least a part of the surface of at least one thermoplastic plastic layer is provided with a thermoreversible adhesive layer. 6. A method according to any one of the preceding claims, characterized in that in step a) a thermoreversible glue foil is applied between at least one metal layer 30 and a thermoplastic plastic layer. Method according to one of the preceding claims, characterized in that the assembly formed in step a) consists essentially of a first and a second metal layer between which a thermoplastic plastic layer is present. 1029469- A method according to any one of the preceding claims, characterized in that an assembly is formed in step a) which comprises a first and at least a second metal layer, the second metal being different from the first. 5 A method according to any one of the preceding claims, characterized in that an assembly is formed in step a) which comprises a first and at least one second thermoplastic plastic layer, wherein the second plastic differs from the first. 10 A method according to any one of the preceding claims, characterized in that the first temperature is higher than the glass transition temperature of the thermoplastic plastic or higher than the lowest glass transition temperature in the case where several thermoplastic plastics are used. 15 A method according to any one of the preceding claims, characterized in that the first temperature is higher than the melting temperature of the thermoplastic plastic or higher than the lowest melting temperature in the case where several thermoplastic plastics are used. 20 A method according to any one of the preceding claims, characterized in that the first temperature is higher than the melting temperature of the thermoreversible glue. 13. A method according to any one of the preceding claims, characterized in that the second temperature is lower than the melting temperature of the thermoreversible glue. A method according to any one of the preceding claims, characterized in that at least one of the thermoplastic plastic layers comprises a fiber-reinforced plastic. 30 Method according to one of the preceding claims, characterized in that an assembly is formed in step a) which comprises at least one fiber layer. 1029469? % · I! A method according to claim 14 or 15, characterized in that the fiber layer and / or the fiber-reinforced plastic layer comprise substantially continuous fibers that extend in two substantially orthogonal directions. A method according to claim 14 or 15, characterized in that the fiber layer and / or the fiber-reinforced plastic layer comprise substantially continuous fibers that extend substantially in one direction. 18. Method as claimed in any of the foregoing claims, characterized in that the method is carried out according to the roll-forming process wherein the at least one metal layer in the form of a continuous metal plate and the at least one thermoplastic plastic layer in the form of a continuous plastic plate are continuous are supplied and stacked at the first temperature, whereafter they are deformed with the aid of at least one forming roller brought to the second temperature. 15 19. Device for manufacturing a molded part from a composite material, which comprises at least one metal layer and a thermoplastic plastic layer, which device comprises at least means for d) being able to stack at least one metal layer and at least one thermoplastic plastic layer; e) being able to bring the assembly thus formed to a first temperature; f) being able to deform the assembly using a shaping tool brought to a second temperature, the at least one metal layer and the at least one thermoplastic plastic layer being interconnected. 25 20. Device as claimed in claim 19, characterized in that the device comprises a pulling device for continuously supplying at least one metal layer in the form of a continuous metal plate and at least one thermoplastic plastic layer in the form of a continuous plastic plate, that they furthermore means for being able to continuously stack the layers at the first temperature, and that it comprises a deforming tool that can be brought to the second temperature in which the stack can be continuously deformed. 1029469 *; 21. Partially consolidated stacking of at least one metal layer and at least one thermoplastic plastic layer. Partially consolidated stack according to claim 21, characterized in that it has an ILSS measured according to ASTM D2344 of at most 60% of the ILSS of the molded part. 23. The use of the stack according to claims 21 and 22 for the manufacture of a molded part from a composite material, which comprises at least one metal layer and a thermoplastic plastic layer. 1029469s