METHOD FOR PRODUCING A FIBER-REINFORCED POLYMER CONTINUOUS PROFILE

Description

[0001] The invention relates to a method for producing a fiber-reinforced polymer end-iso profile.

[0002] Such a method is known, for example, from EP 2 528 723 B1 or DE 10 2016 119766 A1. For hollow chamber profiles used to frame glass panes in windows and doors, there is a fundamental need to achieve the best possible thermal insulation while simultaneously requiring sufficient mechanical stability. Therefore, if such a hollow chamber profile is manufactured by extrusion from unreinforced thermoplastic material, such as polyvinyl chloride (PVC), the insertion of a metallic reinforcing profile into at least one of the hollow chambers is generally necessary for structural reasons. While this significantly improves mechanical stability, this advantage comes at the cost of considerably poorer thermal insulation properties due to the metallic reinforcing profile simultaneously acting as a thermal bridge.

[0003] To counteract this disadvantage, fiber-reinforced PVC profiles have been established in the market for some time. For example, EP 2 191 090 B1 describes the incorporation of short glass fibers into the PVC matrix, which eliminates the need for metal reinforcement in many applications.

[0004] To increase the length of the reinforcing fibers incorporated into the final product during extrusion, EP 2 953 775 A1 proposes coating the corresponding reinforcing fibers with a PVC coating as granules before they are introduced into the extrusion process. This coating provides a degree of protection against the high mechanical stress placed on the fibers during extrusion. This ensures a greater fiber length in the final product and thus higher mechanical stiffness.

[0005] Further improvements in mechanical properties, combined with good thermal insulation, are achieved by incorporating non-metallic reinforcing strips, such as organosheets, into the hollow chamber profile. Such a method is described in EP 2 493 673 A1. These organosheets typically have continuous fibers and can therefore significantly increase the mechanical strength of the profile.

[0006] The measures described above can achieve a significant increase in stiffness compared to an unreinforced PVC profile. However, this is still insufficient for many applications. For this reason, aluminum profiles, which possess outstanding mechanical strength, are still frequently used for door or window frames with very large glazed areas spanning several square meters. The obvious disadvantage of these profiles is their poor thermal insulation, which is why such profiles must be equipped with comparatively complex thermal break constructions. Another disadvantage of aluminum profiles is their relatively high weight and high cost.

[0007] Processes with the characteristics described above are known, for example, from EP 2 528 723 B1 and WO 2018 / 072878 A1. The pultrusion processes disclosed therein allow the production of continuous profiles with very high stiffness. However, these processes generally have the disadvantage that, compared to extrusion processes, they can only be operated at comparatively low production speeds, since full-surface impregnation of the reinforcing fibers with the matrix material is essential for the mechanical performance of the produced continuous profiles.

[0008] Against this background, the invention is based on the objective of specifying a method with the features described above that allows for an increased production speed.

[0009] According to the invention, this problem is solved by curing the core profile using a dual-cure process. Dual-cure processes are generally known in practice, for example, for curing thermoset materials, and more generally refer to the combination of two different curing mechanisms, such as irradiation with light waves on the one hand and with long-wave thermal radiation on the other. Conventional pultrusion with thermal curing is slow and often uneconomical. Electron beam curing or curing with UV radiation allows for significantly shorter curing times and higher production speeds. However, a disadvantage of pure radiation curing is the limited penetration depth of the radiation, meaning that only near-surface areas of the pultruded profile can be cured.By employing a dual-cure process according to the invention, the advantages of the individual curing mechanisms can be combined, and complete curing of the continuous profile can be achieved even at high throughput speeds. In this context, it is particularly advantageous if the feed material for the pultrusion matrix is ​​low-viscosity to facilitate wetting of the reinforcing fibers with this material. Therefore, the feed material for producing the polymeric matrix preferably has a dynamic viscosity of 100–10,000 MPas at 20 °C, preferably 500–1,000 MPas. The weight fraction of the reinforcing fibers in the core profile is expediently 50–85%. The wall thickness of the core profile can, for example, be in the range of 1–8 mm.

[0010] For example, the core profile material contains at least two components that can be cured using different curing processes. A first component, for instance, can be UV-reactive (e.g., an acrylate and / or methacrylate with isocyanate-reactive groups) and combined with a second component containing functional groups for a different curing mechanism, such as thermal or microwave curing. This second component can, for example, contain an XH-terminated component, such as OH-, NH-, or SH-. In general, the core profile matrix material can also contain pigments, such as color pigments, flame retardants (e.g., aluminum trihydrate), UV stabilizers, anti-adhesion additives (e.g., siloxane, fluorine), and / or surfactant additives.In a preferred embodiment of the invention, the core material for producing the core profile comprises polythiols, methyl methacrylates, lactams, or stabilized single-component systems, in particular stabilized thiols. The aforementioned materials are advantageously characterized by their free-flowing nature, thus allowing for high-speed impregnation of the reinforcing fibers. These materials can be combined, for example, with isocyanates, epoxy resins, acrylates, or polysulfides.

[0011] The continuous strand of reinforcing fibers can contain continuous reinforcing fibers oriented unidirectionally in the profile direction. However, it is also within the scope of the invention that this reinforcing strand contains at least one roving, at least one woven fabric, at least one nonwoven fabric, or at least one tape of reinforcing fibers. The reinforcing fibers themselves are preferably made of glass and / or carbon fibers and / or mineral and / or polymer and / or natural fibers.

[0012] According to the invention, the dual-cure process comprises UV curing and thermal curing. In particular, the thermal curing can be performed downstream of the UV curing. Naturally, it is also within the scope of the invention to employ more than two curing processes, i.e., to supplement the dual-cure process according to the invention with at least one further curing process. Furthermore, it is within the scope of the invention to combine thermal curing at significantly elevated temperatures, e.g., above 100 °C, with a second curing process that takes place at room temperature. Of course, the individual curing processes mentioned above can also be combined with one another in any order to form a dual-cure process, e.g., UV curing with subsequent curing at room temperature, UV curing with subsequent electron beam curing, or vice versa, etc.

[0013] To improve the surface quality of the continuous profile or to color it, the core profile is expediently provided with an extruded outer thermoplastic coating immediately after its forming – analogous to the procedure in co-extrusion. This coating is preferably unreinforced, i.e., free of reinforcing fibers. It is advantageous if the coating is made of a polymer that adheres to the core profile, in particular a polyacrylate, a polyester, or a polyamide. Furthermore, the invention allows for the addition of color pigments to the coating material before its application to the core profile.

[0014] According to a preferred embodiment of the invention, the second curing process of the dual-cure process is a thermal curing process, wherein the heat input required for this is achieved by applying the hot extrusion melt of the coating to the core profile. This means that the process step of thermal curing the core profile is combined with the application of the coating, which simplifies the process technology and reduces the energy required for profile production.

[0015] The disclosure further relates to a continuous profile produced using the inventive method described above. In particular, the continuous profile can be configured as a frame or sash profile for a window or door. However, it is also within the scope of the invention, for example, that the continuous profile is configured as a rail profile, preferably symmetrical in cross-section, for a sliding lid of a freezer. In this case, an arc shape is advantageously embossed onto the continuous profile in the axial direction during or after pultrusion. Other uses of the continuous profile produced according to the invention are not excluded by this. The inventive method can be operated at production speeds of at least 2 m / min, e.g., 2–20 m / min, and in particular 3–8 m / min.

[0016] The invention will now be explained in detail with reference to a drawing that illustrates only one embodiment. The drawing schematically shows: Fig. 1 shows a method according to the invention for producing a window hollow chamber profile; Figs. 2a-c show, for example, a method according to the invention. Fig.1 Manufactured hollow chamber profiles in a cross-sectional view, Fig. 3a, further embodiments of the invention

[0017] The Fig. 1 Figure 1 shows a method according to the invention for producing an endless fiber-reinforced polymer window hollow chamber profile 1. The hollow chamber profile 1 has a core profile 10 with several hollow chambers 2, 2' (cf. Figure 1). Fig. 2a-c ) which is produced using a pultrusion process 3 at 80 to 240 °C, preferably 120 to 200 °C. During this pultrusion process 3, continuous reinforcing glass fibers 5 are integrated into the polymer matrix 4 of the core profile 10. These fibers are first unwound from rolls 6 and preheated in a preheating station 7. Using a drawing die 8, the freshly produced core profile 10 is drawn out of the heated pultrusion die 9 over the continuous reinforcing fibers 5 in the production direction x. The polymer matrix 4 of this core profile 10 is produced from low-viscosity components K1 and K2, which are cured using two different curing mechanisms in a dual-cure process. Components K1 and K2 for the production of the polymeric matrix 4 have a dynamic viscosity of 500 - 1000 MPas at 20 °C and contain, for example, polythiols, methyl methacrylates, lactams or stabilized thiols.

[0018] According to the invention, the dual-cure process comprises UV curing of component K1 and thermal curing of component K2, with the thermal curing being performed downstream of the UV curing. Thus, immediately after the impregnation of the reinforcing fibers 5 with components K1 and K2, component K1 is UV cured by appropriate irradiation 70, for example using a mercury vapor lamp or LEDs.

[0019] To improve the surface quality of the hollow chamber profile 1, the core profile 10 produced by pultrusion 3 is provided, after its forming at a temperature of 160–300 °C, preferably 200–260 °C, with an extruded outer coating 12 made of an unreinforced polymer 15, e.g., a polyacrylate, a polyester, or a polyamide, which adheres to the core profile 10, by means of a co-extrusion 11. In the embodiment according to Fig. 1 This coextrusion 11 takes place by means of an extruder 16 immediately following the pultrusion 3 without intermediate cooling. The coextrusion die 13 is arranged directly behind the exit of the die 9 for the pultrusion 3 and encases the core profile 10 in real time. According to the invention, the second curing process of the dual-cure process for curing component K2 is a thermal curing process, whereby the heat input required for this is achieved by applying the hot extrusion melt of the coating 12 to the core profile 10. Consequently, in the exemplary embodiment, the second step of the dual-cure process for curing component K2 and the coextrusion 11 of the coating 12 are combined into a single process step. Only then is the coextruded hollow chamber profile 1 cooled in a cooling device 14, e.g., a water bath.The production speed v for manufacturing the hollow chamber profile 1 is at least 2 m / min, e.g. 2 - 10 m / min.

[0020] The Fig. 2a bis 2c show manufactured hollow chamber window profiles 1, which are, for example, combined with the in Fig. 1 described methods can be produced. The enlarged section of the Fig. 2a shows the thermoplastic matrix 4 of the (in Fig. 2a bis 2c The black-colored core profile 10 contains embedded reinforcing fibers 5 and a coating 12 made of coating material 15, which is shown here in an exaggeratedly thick form. The coating 12 has a layer thickness s of 0.1 to 1 mm, preferably 0.2 to 0.5 mm. In this embodiment, the weight fraction of the reinforcing fibers 5 in the core profile 10 is more than 80%. In this embodiment, Fig. 2a Two further hollow chambers 2' are formed jointly by the core profile 10, which has several hollow chambers 2, and the coating 12. Accordingly, in this embodiment, the coating 12 is only applied to the outer surface of the core profile 10 in certain areas; the outer surface of the core profile 10 is not coated in the connection areas 17 of the hollow chambers 2' formed jointly by the core profile 10 and the coating 12, since these connection areas 17 are not visible from the outside. The hollow chamber profiles 1 also comprise, in all embodiments according to the Fig. 2a bis 2c Functional elements 18, 18' in the form of receiving grooves for (not shown) sealing elements or locking elements, wherein the receiving grooves 18 are located in the Fig. 2a und 2b each is formed solely from the material 15 of the coating 12 - i.e., without core profile 10. In Fig. 2c In contrast, the functional elements 18 are each formed by a coated cross-sectional area of ​​the core profile 10; that is, the core profile 10 contributes significantly to the shape of the functional elements. In the Fig. 2a bis 2c The window hollow chamber profile 1 is designed as a sash frame profile. Accordingly, the core profile 10 has a rebate base 19 for receiving at least one (not shown) pane of glass. In the Fig. 2b und 2c The coating 12 is applied almost completely to the outer surface of the core profile 10. Only the groove base of the respective right-hand receiving groove 18' is formed solely by the core profile 10, and this also applies to the embodiment according to Fig. 2a This applies. Furthermore, in all three embodiments, according to... Fig. 2a bis 2c only formed by the coating 12 projections 20 of a Euro groove 21 of the hollow chamber profile 1 for receiving (not shown) locking elements.

[0021] The in Fig. 2a bis 2c The hollow chamber profiles 1 shown can be colored accordingly by adding color pigments 22 to the material 15 of the coating 12 before application to the core profile 10. In addition to the use of classic white pigments 22, e.g., titanium dioxide, color pigments 22 can also be used, in particular, which give the coating 12 a "real" color and result, for example, in a red, green, blue, gray, yellow, or even black coloration of the hollow chamber profile 1. Not shown in the exemplary embodiments, but also possible within the scope of the invention, is that the outer coating is applied to the core profile 10 as a liquid and / or powder and then cured to form a lacquer layer.

[0022] In the exemplary embodiment according to Fig. 3a The window hollow chamber profile 1 is designed as the core element, which is provided with a sheathing 30, 30' on both the inside and outside. These sheathing 30, 30' can be made of aluminum, wood, or plastic and define the design of the overall profile composed of the elements 1, 30, 30'. When forming a door or window frame with, for example, four corners, the corner joints between the sheathing 30, 30' can be omitted, as the corner joints of the entire frame are created by corresponding corner welds of the mitered window hollow chamber profiles 1 (here, the core elements).

[0023] In the exemplary embodiment according to Fig. 3bA rectangular hollow chamber frame 100 of a window or door profile is formed by first cutting a hollow chamber profile 1 according to the invention at each of the corners 50 at a corresponding miter, so that only the outer wall 60 remains. The hollow chamber frame 100 is then formed by folding the remaining outer wall 60 at each corner 50. Thus, the entire hollow chamber frame 100 (usually composed of four profiles) consists here of a single hollow chamber profile 1, which is connected to itself at one of the corners to form a closed frame 100, preferably by welding. An advantage of this is that the reinforcing fibers 5 completely encircle the outer wall 60 and thus contribute to very high stability.

Claims

1. Method for producing a fibre-reinforced polymer continuous profile (1), - wherein the continuous profile (1) having at least one hollow chamber (2, 2') comprises a core profile (10) which is produced by means of a pultrusion process, and - wherein, during the pultrusion process, at least one continuous strand with reinforcing fibres (5) is integrated into the polymer matrix (4) of the core profile (10), characterised in that curing of the core profile (10) is carried out by means of a dual-cure process and in that the dual-cure process consists of UV curing and thermal curing.

2. Method according to claim 1, characterised in that the feed material (K1, K2) for producing the polymer matrix (4) has a dynamic viscosity of 100-10,000 mPa·s at 20 °C, preferably 500-1,000 mPa·s.

3. Method according to claim 1 or 2, characterised in that the feed material (K1, K2) for producing the core profile (10) contains polythiols, methyl methacrylates, lactams or stabilised one-component systems, in particular stabilised thiols.

4. Method according to one of claims 1 to 3, characterised in that the thermal curing is subsequent to the UV curing.

5. Method according to one of claims 1 to 4, characterised in that the core profile (10) is provided, immediately after its forming, with an extruded outer thermoplastic coating (12).

6. Method according to claim 5, characterised in that the coating (12) is produced from a polymer (15) adhering to the core profile (10), in particular a polyacrylate, a polyester or a polyamide.

7. Method according to claim 5 or 6, characterised in that colour pigments (22) are added to the material (15) of the coating (12) before application to the core profile (10).

8. Method according to one of claims 5 to 7, characterised in that the second curing operation of the dual-cure process is thermal curing, wherein the heat input required for this is provided by applying the hot extrusion melt of the coating (12) to the core profile (10).