Co-extrusion equipment and method for weather-resistant composite material profile

Abstract

The invention relates to the technical field of composite material manufacturing, in particular to co-extrusion equipment and method for a weather-proof composite material section, the equipment comprises a pultrusion die, the pultrusion die at least comprises three sections in the direction of an infiltration tank of the pultrusion die, and the temperatures of the three sections are controlled to be 50-100 DEG C, 140-200 DEG C and 160-200 DEG C respectively; wherein a second glue injection port communicated with the infiltration tank is arranged between the third section and the fourth section, the PVDF extruder is communicated with the second glue injection port, the temperature of the PVDF extruder is gradually increased from the far end of the PVDF extruder to the second glue injection port, and the temperature of the second glue injection port is controlled to be 180-200 DEG C. The pultrusion mold of the co-extrusion equipment is subjected to segmented temperature control, resin in a high-temperature viscous flow state and PVDF melt are subjected to mutual diffusion and reaction on a contact interface by means of high temperature and then are gradually cured and formed, the process of coating the PVDF film on the surface layer remarkably improves the weather resistance of the thermosetting composite material, the equipment cost is controllable, the production efficiency is improved, and the production cost is reduced. And the production cost is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of composite material manufacturing, and in particular to a co-extrusion device and method for weather-resistant composite material profiles. Background Art

[0002] Composite profiles are generally made of thermosetting resin and glass fiber yarn pultrusion. Composite profiles are widely used in chemical industry, wind power and other fields due to their advantages of light weight, high strength and corrosion resistance. Thermosetting resins mainly include polyurethane resin, unsaturated polyester resin, vinyl ester resin, epoxy resin, etc. When composite profiles are exposed to the outdoors for a long time, because the thermosetting resin body cannot meet the stringent weather resistance requirements of the components, it is necessary to coat a layer of weather-resistant material on the surface of the composite profile.

[0003] Regarding the weather resistance of composite material profiles, the method currently widely used in the industry is to coat the composite material profiles with protection through a spray production line process after the composite material profiles are formed. For example, the Chinese invention patent publication number is CN106903910B, and the name is: a coating method for polyurethane pultrusion composite materials. The method disclosed in the invention includes: a) preparing a polyurethane pultrusion composite material by a polyurethane pultrusion process, and the polyurethane pultrusion process includes the steps of: impregnating a fiber reinforcement material with a polyurethane resin, and then curing the impregnated fiber reinforcement material in a mold to provide a polyurethane pultrusion composite material; and b) pulling the polyurethane pultrusion composite material away from the mold, and then applying a water-based coating online to the part of the polyurethane pultrusion composite material with a temperature of 30°C to 90°C. This coating process generally has the disadvantages of high energy consumption, large floor space, long process, and low paint rate; and when the coating is a solvent-based product, it will also bring environmental problems.

[0004] In addition, there have also been reports of manufacturing processes that use pultrusion followed by bonding, covering or co-extrusion. For example, for example, the Chinese patent application publication number: CN114728478A, title: Multilayer pultruded structure with chemical resistance and weather resistance top layer, the patent application discloses that the structure includes from the inside to the outside: a) a pultruded structure containing a fiber-reinforced thermosetting or thermoplastic resin; b) one or more optional bonding layers, c) one or more thermoplastic cover layers, and d) a thin outermost chemical resistant layer; its manufacturing method is a) using a pultrusion molding process to form a fiber-reinforced structure, b) optionally applying one or more bonding layers to the pultruded structure, c) adhering one or more cover layers to the pultruded structure, d) adhering a chemical resistant layer to the pultruded structure; wherein the optional (one or more) bonding layers, cover layers and chemical resistant layers are co-extruded onto the pultruded structure. However, the above-mentioned manufacturing methods are either too complicated, or the produced profiles have various problems including unsightly and easy to peel, and are difficult to promote in industrial production. Summary of the invention

[0005] In view of the technical problems existing in the prior art, this application adopts a co-extrusion equipment and method for weather-resistant composite material profiles, which can directly produce composite materials with PVDF film on the surface. The equipment cost is controllable, the production efficiency and cost are greatly reduced, and the product has excellent weather resistance.

[0006] On the one hand, the present application proposes a co-extrusion device for weather-resistant composite material profiles, including a pultrusion die 3, wherein the pultrusion die 3 has an impregnation tank. Along the direction of the impregnation tank, the pultrusion die 3 includes at least three sections, which are respectively a third section 33, a fourth section 34 and a fifth section 35; the temperature of the third section 33 is controlled at 50°C to 100°C, the temperature of the fourth section 34 is controlled at 140°C to 200°C, and the temperature of the fifth section 35 is controlled at 160°C to 200°C; a second injection port 38 connected to the impregnation tank is provided between the third section 33 and the fourth section 34, the PVDF extruder 5 is connected to the second injection port 38, and the temperature of the second injection port 38 is controlled at 180°C to 200°C.

[0007] In particular, the longitudinal cross-sectional areas of the wetting grooves in the third section 33 , the fourth section 34 and the fifth section 35 do not change.

[0008] In particular, the pultrusion die 3 includes five sections, which are the first section 31, the second section 32, the third section 33, the fourth section 34 and the fifth section 35 respectively; the first section 31 is the yarn guide area at the die entrance, and the longitudinal cross-sectional area of ​​the wetting groove in this area remains unchanged and is not heated; the second section 32 is the fiber impregnation area, and the second section 32 is provided with a raw material injection port 4, and the longitudinal cross-sectional area of ​​the wetting groove in this area changes, and there are conical impregnation grooves before and after the raw material injection port 4, which are not heated.

[0009] In particular, the pultrusion die 3 includes four sections, namely the second section 32, the third section 33, the fourth section 34 and the fifth section 35; the wetting groove in the second section 32 is a trumpet-shaped flow channel and the cross-sectional area of ​​the flow channel gradually decreases to the same as the cross-sectional area of ​​the wetting groove in the third section 33.

[0010] Particularly, an isolation section 36 is provided between the second section 32 and the third section 33 .

[0011] Particularly, the PVDF extruder 5 is a single screw extruder, including three-zone heating, the temperature of the first zone 51 of the extruder is controlled at 150°C to 170°C, the temperature of the second zone 52 of the extruder is controlled at 180°C to 200°C, and the temperature of the third zone 53 of the extruder is controlled at 180°C to 200°C.

[0012] Particularly, the temperature of the first zone 51 of the extruder is controlled at 160°C, the temperature of the second zone 52 of the extruder is controlled at 190°C, the temperature of the third zone 53 of the extruder is controlled at 190°C, and the temperature of the second injection port 38 of the PVDF extruder 5 injected into the pultrusion die 3 is controlled at 190°C.

[0013] In particular, the equipment includes a preforming mold 2 and a pultrusion mold 3 connected in sequence, wherein the preforming mold 2 is composed of a group of yarn guide plates with multiple holes or grooves, which open holes or grooves on several metal plates according to the cross-sectional shape of the profile to guide the fiber-reinforced material to gradually form a preformed body with a shape and size similar to the molding cavity.

[0014] In particular, the device comprises an open impregnation tank 8 which is arranged upstream of the pultrusion die 3 .

[0015] On the other hand, the present application also proposes a co-extrusion method for a weather-resistant composite material profile, using the co-extrusion equipment as mentioned above, the fiber 1 is impregnated with the polyurethane prepolymer polyol and isocyanate, and then preheated in the third section 33, the raw material reaction is transformed into a gel-state resin, and at the same time, the polyvinylidene fluoride PVDF is melted by the PVDF extruder 5, and the PVDF melt temperature is between 180°C and 200°C. After metering, the PVDF melt is pumped into the wetting tank inside the pultrusion die 3 along the second glue injection port 38 to become the surface layer of the resin. The resin covering the PVDF is heated in the fourth section 34, the resin gradually solidifies and the surface is fully bonded to the PVDF, and finally enters the fifth section 35 to release the internal stress under high temperature for heat setting.

[0016] On the basis of conforming to the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present application.

[0017] The above technical solution has the following advantages or beneficial effects: the pultrusion die of the co-extrusion equipment of the present application is temperature-controlled in sections, and the resin in the high-temperature viscous flow state and the PVDF melt diffuse and react with each other at the contact interface with the help of high temperature, and then gradually solidify and form. This process of coating the surface with PVDF film significantly improves the weather resistance of thermosetting composite materials, the equipment cost is controllable, the production efficiency is improved, and the production cost is reduced. Of course, any technical solution of the present application does not necessarily achieve all the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art description. Obviously, for those skilled in the art, other drawings can be obtained based on the provided drawings without creative work.

[0019] Figure 1It is a schematic structural diagram of a co-extrusion device for a weather-resistant composite material profile according to an embodiment of the present application.

[0020] Figure 2 It is a schematic structural diagram of a closed-type dipping pultrusion die according to an embodiment of the present application.

[0021] Figure 3 It is a schematic structural diagram of another co-extrusion device for weather-resistant composite material profiles according to an embodiment of the present application.

[0022] Figure 4 It is a schematic structural diagram of an open-type dipping pultrusion die according to an embodiment of the present application.

[0023] Figure 5 It is a schematic structural diagram of a PVDF extruder according to an embodiment of the present application.

[0024] Figure 6 It is a schematic structural diagram of a weather-resistant composite material profile according to an embodiment of the present application.

[0025] Figure 7 It is a schematic diagram of the structure of a weather-resistant layer and a substrate according to an embodiment of the present application.

[0026] Figure 8 This is a microscopic picture (magnified 60 times) of the appearance of the weather-resistant layer side of the weather-resistant composite material profile after being torn open according to an embodiment of the present application.

[0027] Fig. 9 This is a microscopic picture (magnified 60 times) of the appearance of the substrate side of a weather-resistant composite material profile after being torn open according to an embodiment of the present application.

[0028] Among them, fiber 1, preforming mold 2, pultrusion mold 3, first section 31, second section 32, third section 33, fourth section 34, fifth section 35, isolation section 36, first glue injection port 37, second glue injection port 38, raw material injection device 4, PVDF extruder 5, first zone 51, second zone 52, third zone 53, traction machine 6, composite frame profile 7, dipping tank 8, first horizontal edge 91, first side edge 92 and second horizontal edge 93, first space 94, matrix 95, weather-resistant layer 96. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application are clearly and completely described below in conjunction with the drawings of the present application. Obviously, the described embodiments are only part of the embodiments of the present application and are intended to be used to explain the inventive concept. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application.

[0030] The orientation or position relationship indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential", etc. used in the description are based on the orientation or position relationship shown in the drawings and are only for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation.

[0031] The terms "first", "second", etc. used in the description are only used for descriptive purposes and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features specified as "first" or "second" may explicitly or implicitly include one or more of the features. The term "plurality" means two or more, unless otherwise clearly and specifically specified.

[0032] Unless otherwise clearly specified and limited, the terms "connected", "connected" and the like used in the description should be understood in a broad sense, for example, it can be fixedly connected, detachably connected, or integrated; it can be mechanically connected, electrically connected; it can be directly connected, indirectly connected through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments can be understood according to specific circumstances.

[0033] Unless otherwise clearly specified and limited, when a first feature is “above”, “below” or “above” a second feature, it may be that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is “above”, “above” or “above” a second feature, it may be that the first feature is directly above or obliquely above the second feature, or it may simply mean that the first feature is higher in level than the second feature. When a first feature is “below”, “below” or “below” a second feature, it may be that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is “below”, “below” or “below” a second feature, it may be that the first feature is directly below or obliquely below the second feature, or it may simply mean that the first feature is lower in level than the second feature.

[0034] The term "a specific embodiment" used in the description means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0035] refer to Figure 1 and Figure 2 A specific embodiment of the present application proposes a co-extrusion device for a weather-resistant composite material profile, including a preforming mold 2, a pultrusion mold 3, a raw material injection device 4 and a PVDF extruder 5, wherein the pultrusion mold 3 includes at least five sections, which are respectively a first section 31, a second section 32, a third section 33, a fourth section 34 and a fifth section 35.

[0036] The preforming mold 2 is composed of a group of yarn guide plates with multiple holes or grooves. The holes or grooves are opened on several metal plates according to the cross-sectional shape of the profile to guide the fiber-reinforced material to gradually form a preformed body with a shape and size similar to the molding cavity, and then enter the pultrusion mold 3, so as to ensure that the yarn content of the product cross section is uniform. The specific structure of the five sections of the pultrusion mold 3: the first section 31 is the yarn guide area at the mold entrance. The longitudinal cross-sectional area of ​​the impregnation groove in this area is unchanged, and it is not heated and kept at room temperature. The second section 32 is the fiber impregnation area. The second section 32 is provided with a raw material injection port 4. The longitudinal cross-sectional area of ​​the impregnation groove in this area changes. There are conical impregnation grooves before and after the raw material injection port 4. It is not heated and kept at room temperature. The function of this area is to allow the liquid mixture of polyol and isocyanate to impregnate the fiber 1. The lower the liquid viscosity, the better. The third section 33 is a preheating gel zone, which is provided with a temperature regulating device. The longitudinal cross-sectional area of ​​the wetting tank in this zone does not change. The temperature in this zone is controlled at 50°C to 100°C. The longitudinal cross-sectional area of ​​the wetting tank in this zone does not change. The liquid mixture of polyol and isocyanate in this zone begins to react, and the mixture changes from liquid to gel state. The fourth section 34 is a heating and curing zone. A PVDF extruder 5 is provided between the third section 33 and the fourth section 34. The PVDF extruder 5 extrude PVDF melt into the wetting tank and covers the surface of the polyurethane resin in gel state. The fourth section 34 is provided with a temperature regulating device. The longitudinal cross-sectional area of ​​the wetting tank in this zone does not change. The temperature in this zone is controlled at 140°C to 200°C. The liquid mixture of polyol and isocyanate in this zone reacts quickly from gel state to solid state. The fifth section 35 is a surface forming area, which is provided with a temperature regulating device. The longitudinal cross-sectional area of ​​the wetting tank in this area remains unchanged, and the temperature of this area is controlled at 160°C to 200°C. The function of this area is to make the PVDF surface smooth. In addition, this area also has the function of releasing internal stress and thermally setting under high temperature conditions, thereby obtaining a PVDF film layer with a smooth surface.

[0037] Preferably, in order to minimize the high-temperature heat conduction from the third section 33 to the second section 32, thereby causing the viscosity of the polyol and isocyanate to increase and resulting in a decrease in the wetting ability, an isolation section 36 is provided between the two sections. For example, cooling water can be introduced into the isolation section 36 to ensure that the temperature of the second section 32 is maintained at room temperature.

[0038] The operation method of the co-extrusion equipment of the present application is as follows: the fiber 1 enters the pultrusion die 3 along the guide device of the preforming die 2, and the polyurethane prepolymer polyol and isocyanate are metered and mixed in a static mixer and then injected into the wetting tank of the second section 32 by the raw material injection device 4 along the first injection port 37, and the mixture of polyol and isocyanate fully impregnates the fiber 1 in the second section 32; then, after preheating in the third section 33, the raw material reaction is transformed into a gel-state resin, and at the same time, after the polyvinylidene fluoride PVDF is melted by the PVDF extruder 5, the PVDF melt temperature is between 180°C and 200°C. After metering, the PVDF melt is pumped into the wetting tank inside the pultrusion die 3 along the second injection port 38 and then becomes the surface layer of the resin. At this time, the resin covered by the PVDF melt is still in a gel state and has not been completely solidified. The gel-state resin and the PVDF melt are both in a high-temperature viscous flow state, and the high temperature is used to diffuse and react with each other at the contact interface between the two. The resin covering the PVDF is heated in the fourth section 34, the resin is gradually solidified and the surface is fully bonded to the PVDF, and finally enters the fifth section 35 and releases the internal stress under high temperature for heat setting to obtain a PVDF film layer with a smooth surface. Finally, the composite frame profile 7 with a PVDF weather-resistant skin layer is pulled out of the pultrusion die 3 under the traction of the traction machine 6, and the weather-resistant composite material profile can be obtained by cutting with a cutting machine.

[0039] refer to Figure 3 and Figure 4 A specific embodiment of the present application proposes another co-extrusion device for weather-resistant composite material profiles, including a dipping tank 8, a pultrusion die 3, and a PVDF extruder 5. The main difference between this open dipping pultrusion process and the above-mentioned closed dipping pultrusion process is only the difference in the dipping method. The open dipping uses a dipping tank for dipping, and the closed dipping injects the raw materials into the impregnation tank by high pressure for dipping. In the open dipping, the fiber 1 enters the open dipping tank 8 through a yarn guide roller, and then enters the pultrusion die 3 through a yarn guide roller after dipping. In this process, the pultrusion die 3 does not need a yarn guide area, and the inlet of the pultrusion die 3 is a trumpet-shaped flow channel and the cross-sectional area of ​​the flow channel gradually decreases; because the fiber is impregnated in the open dipping tank 8, the oligomer polyol and isocyanate do not need to be injected into the mold under high pressure, so the injection port is also omitted, and the rest is the same as the above-mentioned closed dipping process.

[0040] refer to Figure 5A specific embodiment of the present application proposes another PVDF extruder 5 of a co-extrusion equipment for weather-resistant composite material profiles, which is a single-screw extruder with a diameter of 25 mm, which includes three-zone heating, the temperature of the first zone 51 of the extruder is controlled at 150℃~170℃, preferably 160℃, the temperature of the second zone 52 of the extruder is controlled at 180℃~200℃, preferably 190℃, the temperature of the third zone 53 of the extruder is controlled at 180℃~200℃, preferably 190℃, and the temperature of the second injection port 38 of the PVDF extruder 5 injected into the pultrusion die 3 is controlled at 180℃~200℃, preferably 190℃.

[0041] refer to Figure 6 and Figure 7 A specific embodiment of the present application proposes a weather-resistant composite material frame for photovoltaic cells manufactured using the above co-extrusion equipment. The weather-resistant composite material frame includes a first transverse side 91, a first side 92 and a second transverse side 93. The first transverse side 91, the first side 92 and the second transverse side 93 enclose a first slot-shaped space 94 with an open side. The edge of the crystalline silicon solar cell is plugged and fixed in the first space 94. The weather-resistant composite material includes a substrate 95 and a weather-resistant layer 96 located on the surface of the substrate 95. The substrate 95 is a fiber-reinforced thermosetting composite material. The thermosetting material is selected from polyurethane resin. The thickness of the substrate 95 is 1mm to 10mm; the weather-resistant layer 96 is a fluororesin material, preferably PVDF, and the thickness of the weather-resistant layer 96 is 2 microns to 300 microns. The substrate 95 and the weather-resistant layer 96 are prepared by the above co-extrusion process. The thickness of the weather-resistant layer 96 is 2 microns to 300 microns, preferably 30 to 150 microns.

[0042] The fiber is selected from one of glass fiber, basalt fiber, carbon fiber, polymer fiber, hemp fiber and bamboo fiber or a mixed fiber, and also includes fabrics such as cloth and felt of these fibers. The PVDF refers to pure PVDF or a mixture of PVDF and PMMA. The method is applicable to thermosetting materials such as polyurethane resin, unsaturated polyester resin, vinyl ester resin, epoxy resin, etc.

[0043] Example 1

[0044] Fiber reinforced polyurethane composite pultrusion process, using Figure 1 The device shown in the figure, wherein the isocyanate is Covestro Desmodur 1511L, the polyol is Covestro Baydur 18BD298, and 3% black color paste is used. The pultrusion line speed is 0.7 m / min, and the injection pressure is 1.2 MPa. The glass fiber yarn density is 4800 tex, and the fibers include glass fiber yarn and glass fiber cloth, and the total mass content is 77%. The temperature of the third section 33 is controlled at 80°C, the temperature of the fourth section 34 is controlled at 195°C, and the temperature of the fifth section 35 is controlled at 180°C.

[0045] PVDF single screw extrusion process, PVDF mixture includes 65% PVDF homopolymer with a melt index of 20, 18% acrylic material, 15% titanium dioxide, and 2% additives such as antioxidants and lubricants. The PVDF extruder 5 is a single screw extruder with a diameter of 25 mm. The single screw extruder includes 3-zone heating. The temperature of the first zone 51 of the extruder is set at 160°C, the temperature of the second zone 52 of the extruder is set at 190°C, and the temperature of the third zone of the extruder is set at 190°C. In addition, the temperature of the second injection port 38 of the PVDF extruder 5 injected into the pultrusion die 3 is controlled at 190°C. The screw speed of the single screw extruder is 5 rpm, and the thickness of the co-extruded PVDF skin layer is 0.1 mm.

[0046] The bonding force between the PVDF skin layer and the fiber-reinforced polyurethane matrix varies greatly with the different preheating gel zone temperature settings: when the preheating gel zone temperature is 80°C and 100°C, the bonding force between PVDF and the polyurethane pultrusion substrate is the best; when the preheating gel zone temperature rises to 120°C, the bonding force between PVDF and the polyurethane pultrusion substrate becomes worse; when the preheating gel zone temperature rises to above 140°C, the bonding force between PVDF and the polyurethane pultrusion substrate is as low as 3 to 5N / cm.

[0047]

[0048] Figure 8 is a microscopic photograph of the weather-resistant layer PVDF of the weather-resistant composite material profile prepared in Example 1, close to the substrate side. Fig. 9 This is a microscopic photograph of the fiber-reinforced polyurethane matrix close to the weather-resistant layer of the weather-resistant composite material profile prepared in Example 1. It can be seen that after the co-extruded weather-resistant layer PVDF is peeled off from the matrix, the white weather-resistant layer is bonded with multiple bright strips, which are the glass fibers in the fiber-reinforced polyurethane matrix; there is a lot of white PVDF residue on the bonding surface of the fiber-reinforced polyurethane black matrix; this shows that PVDF has good bonding with the substrate.

[0049] Although the embodiments of the present application have been shown and described above, it is to be understood that the above embodiments are exemplary and cannot be construed as limiting the present application. Without departing from the spirit and scope of the present application, the present application may also have various changes and improvements, which all fall within the scope of the present application to be protected.

Claims

1. A co-extrusion device for a weather-resistant composite material profile, comprising a pultrusion die (3), wherein the pultrusion die (3) has an impregnation tank, and is characterized in that: Along the direction of the impregnation tank, the pultrusion die (3) comprises at least three sections, which are respectively a third section (33), a fourth section (34) and a fifth section (35); the temperature of the third section (33) is controlled at 50°C to 100°C, the temperature of the fourth section (34) is controlled at 140°C to 200°C, and the temperature of the fifth section (35) is controlled at 160°C to 200°C; a second glue injection port (38) connected to the impregnation tank is provided between the third section (33) and the fourth section (34), the PVDF extruder (5) is connected to the second glue injection port (38), and the temperature of the second glue injection port (38) is controlled at 180°C to 200°C.

2. The co-extrusion equipment for weather-resistant composite material profiles according to claim 1, characterized in that: The longitudinal cross-sectional areas of the wetting grooves in the third section (33), the fourth section (34) and the fifth section (35) do not change.

3. The co-extrusion equipment for weather-resistant composite material profiles according to claim 1, characterized in that: The pultrusion die (3) comprises five sections, namely the first section (31), the second section (32), the third section (33), the fourth section (34) and the fifth section (35); the first section (31) is the yarn guide section at the die entrance, the longitudinal cross-sectional area of ​​the impregnation groove in this section remains unchanged and is not heated; the second section (32) is the fiber impregnation section, the second section (32) is provided with a raw material injection port (4), the longitudinal cross-sectional area of ​​the impregnation groove in this section changes, and there are conical impregnation grooves before and after the raw material injection port (4), which are not heated.

4. The co-extrusion device for weather-resistant composite material profiles according to claim 1, characterized in that: The pultrusion die (3) comprises four sections, namely a second section (32), a third section (33), a fourth section (34) and a fifth section (35); the wetting groove in the second section (32) is a trumpet-shaped flow channel and the cross-sectional area of ​​the flow channel gradually decreases to the same as the cross-sectional area of ​​the wetting groove in the third section (33).

5. A co-extrusion device for weather-resistant composite material profiles according to claim 3 or 4, characterized in that: An isolation section (36) is provided between the second section (32) and the third section (33).

6. The co-extrusion device for weather-resistant composite material profiles according to claim 1, characterized in that: The PVDF extruder (5) is a single-screw extruder, comprising three-zone heating, wherein the temperature of the first zone (51) of the extruder is controlled at 150°C to 170°C, the temperature of the second zone (52) of the extruder is controlled at 180°C to 200°C, and the temperature of the third zone (53) of the extruder is controlled at 180°C to 200°C.

7. The co-extrusion device for weather-resistant composite material profiles according to claim 6, characterized in that: The temperature of the first zone (51) of the extruder is controlled at 160°C, the temperature of the second zone (52) of the extruder is controlled at 190°C, the temperature of the third zone (53) of the extruder is controlled at 190°C, and the temperature of the second injection port (38) of the PVDF extruder (5) for injecting into the pultrusion die (3) is controlled at 190°C.

8. The co-extrusion device for weather-resistant composite material profiles according to claim 3, characterized in that: The device comprises a preforming die (2) and a pultrusion die (3) connected in sequence, wherein the preforming die (2) is composed of a group of yarn guide plates with multiple holes or grooves, which open holes or grooves on several metal plates according to the cross-sectional shape of the profile to guide the fiber-reinforced material to gradually form a preformed body with a shape and size similar to the molding cavity.

9. The co-extrusion device for weather-resistant composite material profiles according to claim 4, characterized in that: The device comprises an open-type dipping tank (8) which is arranged upstream of the pultrusion die (3).

10. A method for co-extrusion of a weather-resistant composite material profile, using the co-extrusion device as claimed in claim 1, characterized in that: The fiber (1) is impregnated with polyurethane prepolymer polyol and isocyanate, and then preheated in the third section (33). The raw materials react and transform into a resin in a gel state. At the same time, the polyvinylidene fluoride (PVDF) is melted by the PVDF extruder (5). The PVDF melt temperature is between 180°C and 200°C. After metering, the PVDF melt is pumped into the impregnation tank inside the pultrusion die (3) along the second injection port (38) to form the surface layer of the resin. The resin covering the PVDF is heated in the fourth section (34). The resin is gradually solidified and the surface is fully bonded to the PVDF. Finally, it enters the fifth section (35) to release the internal stress under high temperature and perform heat setting.

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