Device and forming method for ultrasonic-assisted fiber-reinforced pultrusion thermosetting composite material

Abstract

The invention relates to the technical field of reinforced plastic pultrusion, in particular to an ultrasonic-assisted fiber reinforced pultrusion thermosetting composite material device and a forming method. The device comprises a pre-forming die and a pultrusion die which are sequentially connected, the pultrusion die at least comprises five sections, the second section is provided with a raw material injection port and ultrasonic transducers, the ultrasonic transducers are distributed on at least one wall face in the circumferential direction of the second section, the longitudinal cross section area of an infiltration groove in the second section is changed, and the thickness of the infiltration groove in the second section is smaller than that of the raw material injection port. Conical infiltration tanks are arranged in front of and behind the raw material injection port; the temperature of the third section is controlled to be 25-100 DEG C, the temperature of the fourth section is controlled to be 140-200 DEG C, and the temperature of the fifth section is controlled to be 160-200 DEG C. According to the pultrusion device and method, the pultrusion linear speed of the fiber-reinforced thermosetting composite material is increased, and the mechanical property of the thermosetting composite material is improved.

Description

Technical Field

[0001] The present application relates to the technical field of reinforced plastic pultrusion molding, and in particular to a device and molding method for ultrasonic-assisted fiber-reinforced pultruded thermosetting composite materials. Background Art

[0002] Fiber reinforced polymer (FRP) is a high-strength, high-modulus, high-toughness composite material formed by reinforcing fiber materials, such as glass fiber, carbon fiber, aramid fiber, etc., and matrix materials through pultrusion and other molding processes. Fiber reinforced composite materials are widely used in transportation, power generation, chemical industry and other fields due to their excellent mechanical properties, corrosion resistance, insulation, and aging resistance.

[0003] Pultrusion is a common method for preparing fiber-reinforced composites, among which the impregnation problem is a common problem in the preparation of fiber-reinforced composites by pultrusion. Poor impregnation will result in the mechanical properties of the continuous reinforcement material not being fully exerted. Therefore, the industry has made a lot of efforts to improve the impregnation problem of the reinforcement material.

[0004] For example, the Chinese patent application publication number: CN111409293A, title: Ultrasonic enhanced long fiber reinforced polymer composite material impregnation method and ultrasonic enhanced long fiber reinforced polymer composite material, which discloses that long fibers are introduced into a fiber pre-dispersion device, heated and pre-dispersed to obtain pre-dispersed long fibers; the pre-dispersed long fibers are subjected to ultrasonic vibration treatment to obtain ultrasonic treated fibers; polymer melt is mixed with ultrasonic treated fibers, melt impregnation treatment is performed to obtain a mixture of polymer and long glass fibers; the mixture of polymer and long glass fibers is cooled and rolled up to obtain ultrasonic enhanced long fiber reinforced polymer composite materials. Although it improves the fiber surface structure through ultrasonic vibration to promote the interface bonding between long fibers and polymer melt, the impregnation problem is still an obstacle to increasing the linear speed of fiber reinforced composite materials or solving defects such as pores, especially for thermosetting composite materials. Summary of the invention

[0005] In view of the technical problems existing in the prior art, the present application proposes an apparatus and a molding method for ultrasonically assisted fiber-reinforced pultruded thermosetting composite materials.

[0006] On the one hand, the present application proposes an ultrasonically assisted fiber-reinforced pultruded thermosetting composite material device, comprising a preforming mold 2 and a pultrusion mold 3 connected in sequence, wherein the pultrusion mold 3 includes at least five sections, and the five sections are respectively a first section 31, a second section 32, a third section 33, a fourth section 34 and a fifth section 35; the second section 32 is provided with a raw material injection port 4 and an ultrasonic transducer 5, and the ultrasonic transducer 5 is arranged on at least one circumferential wall of the second section 32, and the cross-sectional area of ​​the wetting groove in the second section 32 varies along the longitudinal direction, and the raw material injection port 4 is a conical wetting groove before and after; the temperature of the third section 33 is controlled at 25°C-100°C, the temperature of the fourth section 34 is controlled at 140°C-200°C, and the temperature of the fifth section 35 is controlled at 160°C-200°C.

[0007] Particularly, the longitudinal cross-sectional area of ​​the wetting groove in the first section 31 remains unchanged and is maintained at room temperature.

[0008] Particularly, a single wall surface of the second section 32 is provided with 2-6 ultrasonic transducers 5 .

[0009] 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.

[0010] Particularly, the temperature of the third section 33 is controlled at 80°C, the temperature of the fourth section 34 is controlled at 165°C, and the temperature of the fifth section 35 is controlled at 190°C.

[0011] Particularly, the preforming mold 2 is composed of a group of yarn guide plates with multiple holes or slots.

[0012] Particularly, the fibers account for 30%-85% of the total mass of the profile; the thermosetting composite material includes polyurethane resin, unsaturated polyester resin, vinyl ester resin, and epoxy resin.

[0013] Particularly, a cooling water hole is provided between the second section 32 and the third section 33 for introducing cooling water.

[0014] On the other hand, the present application also proposes a method for forming an ultrasonically assisted fiber-reinforced pultruded thermosetting composite material. Using the above-mentioned device, the fiber 1 enters the pultrusion die 3 along the guidance of the preforming die 2, and the resin raw material enters the second section 32 of the pultrusion die 3 along the raw material injection port 4 after being metered and mixed in the static mixer. The resin raw material infiltrates the fiber 1 in the mold; the ultrasonic transducer installed in the second section 32 applies lateral vibration to accelerate the infiltration of the resin raw material into the fiber 1; after the mold is heated, the resin raw material reacts and solidifies; the composite material profile 7 is pulled out of the pultrusion die 3 under the traction action of the traction machine 6; wherein the frequency of the ultrasonic transducer 5 is 20kHz-75kHz, and the pultrusion line speed is 0.3-1.5 m / min.

[0015] Particularly, the frequency of the ultrasonic transducer 5 is 28kHz-40kHz, and a pulse mode is used.

[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 present application is temperature-controlled in sections, and an ultrasonic device is provided in the infiltration zone at the injection port to assist infiltration, thereby increasing the pultrusion line speed of the fiber-reinforced thermosetting composite material and improving the mechanical properties of the thermosetting composite material. Of course, any technical solution of the present application does not necessarily achieve all of the above advantages 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 1 is a schematic structural diagram of a device for ultrasonically assisted fiber-reinforced pultruded thermosetting composite material according to an embodiment of the present application;

[0020] Figure 2 is a schematic diagram of a cross-sectional structure of a pultrusion die according to an embodiment of the present application;

[0021] Figure 3 It is a schematic cross-sectional view of a pultruded profile according to an embodiment of the present application.

[0022] 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; raw material injection port 4; ultrasonic transducer 5; traction machine 6; thermosetting composite material profile 7. DETAILED DESCRIPTION

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] refer to Figure 1 and Figure 2 A specific embodiment of the present application provides an ultrasonic-assisted fiber-reinforced pultruded thermosetting composite material device, comprising a preforming die 2 and a pultrusion die 3 connected in sequence. The pultrusion die 3 comprises 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.

[0029] 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, and then enter the pultrusion mold 3, thereby ensuring that the yarn content in the cross section of the product is uniform.

[0030] The specific structure of the five sections of the pultrusion die 3 is as follows: the first section 31 is the yarn guide section at the die entrance, and the longitudinal cross-sectional area of ​​the impregnation tank in this section remains unchanged, is not heated, and is kept at room temperature. The second section 32 is the fiber impregnation zone, and the second section 32 is provided with a raw material injection port 4 and an ultrasonic transducer 5; the ultrasonic transducers are arranged on a wall surface or several circumferential walls of the second section; each wall surface preferably has 2-6; the frequency of a single ultrasonic transducer 5 is 20-75kHz, preferably 28-40kHz; preferably a pulse mode is used; the longitudinal cross-sectional area of ​​the impregnation tank in this zone changes, and there are conical impregnation tanks before and after the raw material injection port 4, which are not heated and kept at room temperature. The function of this zone is to allow the liquid mixture of polyol and isocyanate to impregnate the fiber 1. The third section 33 is a preheating zone, which has a heater. The longitudinal cross-sectional area of ​​the impregnation tank in this zone does not change. The temperature of this zone is controlled at 25℃-100℃. When the temperature is 25℃, it means that the heater in this zone can be kept at room temperature without turning on. The function of this zone is to further impregnate the fiber. In addition, it serves as a buffer to reduce the influence of the heat conduction of the fourth section 34 on the temperature of the second section 32. The fourth section 34 is a heating gel zone, which has a heater. The longitudinal cross-sectional area of ​​the impregnation tank in this zone does not change. The temperature of this zone is controlled at 140℃-200℃. The liquid mixture of polyol and isocyanate in this zone begins to react rapidly, and the mixture changes from liquid to gel. The fifth section 35 is a heating curing zone, which has a heater. The longitudinal cross-sectional area of ​​the impregnation tank in this zone does not change. The temperature of this zone is controlled at 160℃-200℃. The function of this zone is to change the resin from gel to solid. In addition, this zone also has the function of releasing internal stress.

[0031] The present invention discloses a method for forming an ultrasonic-assisted fiber-reinforced pultruded thermosetting composite material as follows: using the above-mentioned device, the fiber 1 includes glass fiber, basalt fiber, carbon fiber, polymer fiber, hemp fiber, bamboo fiber, and may also be glass fiber cloth and / or glass fiber composite felt, etc. The fiber 1 enters the pultrusion die 3 along the guidance of the preforming die 2, and the polymer polyol and isocyanate enter the second section 32 of the pultrusion die 3 along the raw material injection port 4 after being metered and mixed in the static mixer, and the mixture of polyol and isocyanate infiltrates the fiber 1 in the die; the ultrasonic transducer installed in the second section 32 applies lateral vibration (perpendicular to the fiber direction), thereby accelerating the infiltration of the mixture of polyol and isocyanate into the fiber 1. After the mold is heated, the mixture of polyol and isocyanate reacts and solidifies. Finally, the composite material profile 7 is pulled out of the mold under the traction of the tractor 6 and sent to the cutting machine for cutting.

[0032] In order to minimize the decrease in wetting ability caused by the increase in viscosity of polyol and isocyanate due to heat conduction from the high temperature of the fourth section 34 to the second section 32, a third section 33 with a temperature of 25°C-100°C is provided between the two sections. In addition, a cooling water hole can be opened between the second section 32 and the third section 33 to allow cooling water to pass through, thereby ensuring that the temperature of the second section 32 is maintained at room temperature.

[0033] The fiber accounts for 30%-85% of the total mass of the profile. The molding method is applicable to thermosetting materials such as polyurethane resin, unsaturated polyester resin, vinyl ester resin, epoxy resin, etc. The pultrusion line speed is 0.3-1.5 m / min.

[0034] Example 1

[0035] Isocyanate is Covestro Desmodur 1511L, and polyol is Covestro Baydur 18BD298. The density of glass fiber yarn is 4800tex; the total mass content of glass fiber yarn and glass fiber cloth is 77%. The pultrusion mold is a photovoltaic frame mold, and the cross-section of the pultruded profile is as follows: Figure 3 shown.

[0036] The glass fiber yarn and glass fiber composite felt are introduced into the pultrusion die 3 along the guide device of the preforming die 2. The polymer polyol and isocyanate are mixed through metering and static mixer and then enter the pultrusion die 3 along the raw material injection port 4. The mixture of polyol and isocyanate infiltrates the glass fiber yarn and glass fiber composite felt in the die. Three ultrasonic transducers are arranged in the second section 32 of the pultrusion die 3. The ultrasonic transducer frequency is 40kHz and the pulse mode is used. The ultrasonic transducer applies lateral vibration (perpendicular to the direction of the continuous fiber) to accelerate the infiltration of the fiber reinforcement material by the liquid mixture of polyol and isocyanate. The injection pressure of polyol and isocyanate is 1.2MPa. After the mold is heated, the mixture of polyol and isocyanate reacts and solidifies. The mold is heated in three zones. The temperature of the third section 33 is set to 80°C, the temperature of the fourth section 34 is set to 165°C, and the temperature of the fifth section 35 is set to 190°C. Finally, the composite material profile 7 is pulled out of the mold by the traction of the traction machine 6 and sent to the cutting machine for cutting. The pultrusion line speed is 0.7 m / min.

[0037] Comparative Example 1

[0038] The same as embodiment 1, but the ultrasonic transducer is not started.

[0039] The composite material profiles of Example 1 and Comparative Example 1 were sampled and tested for performance. The weight per gram of Example 1 was 485.92 g / m, while that of Comparative Example 1 was 482.27 g / m, with a weight increase of 0.76%, indicating that the profiles were more compact and dense after ultrasonic vibration.

[0040] The density and bending performance test results are as follows:

[0041]

[0042] It is found that the composite material profile of the embodiment is improved in density, bending strength and bending modulus compared with the comparative example, which are increased by 0.55%, 6.65% and 5.46% respectively. It is also found that the standard deviation of density, bending strength and bending modulus of the embodiment is smaller, which means that the difference between the samples of the embodiment is smaller and the profile is more uniform.

[0043] 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. An apparatus for ultrasonically assisted fiber-reinforced pultruded thermosetting composite material, comprising a preforming die (2) and a pultrusion die (3) connected in sequence, characterized in that: The pultrusion die (3) comprises 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); the second section (32) is provided with a raw material injection port (4) and an ultrasonic transducer (5), the ultrasonic transducer (5) being arranged on at least one circumferential wall surface of the second section (32); the cross-sectional area of ​​the wetting groove in the second section (32) varies along the longitudinal direction, and the sections before and after the raw material injection port (4) are conical wetting grooves; the temperature of the third section (33) is controlled at 25°C-100°C, the temperature of the fourth section (34) is controlled at 140°C-200°C, and the temperature of the fifth section (35) is controlled at 160°C-200°C.

2. The device for ultrasonically assisted fiber-reinforced pultruded thermosetting composite material according to claim 1, characterized in that: The longitudinal cross-sectional area of ​​the infiltration groove in the first section (31) remains unchanged and is maintained at room temperature.

3. The device for ultrasonically assisted fiber-reinforced pultruded thermosetting composite material according to claim 1, characterized in that: A single wall surface of the second section (32) is provided with 2 to 6 ultrasonic transducers (5).

4. The device for ultrasonically assisted fiber-reinforced pultruded thermosetting composite material 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.

5. The device for ultrasonically assisted fiber-reinforced pultruded thermosetting composite material according to claim 1, characterized in that: The temperature of the third section (33) is controlled at 80°C, the temperature of the fourth section (34) is controlled at 165°C, and the temperature of the fifth section (35) is controlled at 190°C.

6. The device for ultrasonically assisted fiber-reinforced pultruded thermosetting composite material according to claim 1, characterized in that: The preforming mold (2) is composed of a group of yarn guide plates with multiple holes or grooves.

7. The device for ultrasonically assisted fiber-reinforced pultruded thermosetting composite material according to claim 1, characterized in that: The fibers account for 30%-85% of the total mass of the profile; the thermosetting composite material includes polyurethane resin, unsaturated polyester resin, vinyl ester resin, and epoxy resin.

8. The device for ultrasonically assisted fiber-reinforced pultruded thermosetting composite material according to claim 1, characterized in that: A cooling water hole is also provided between the second section (32) and the third section (33) for passing cooling water.

9. A method for forming an ultrasonically assisted fiber-reinforced pultruded thermosetting composite material, using the device according to any one of claims 1 to 8, characterized in that: The fiber (1) is guided by the preforming die (2) and then enters the pultrusion die (3). The resin raw material is metered and mixed in a static mixer and then enters the second section (32) of the pultrusion die (3) along the raw material injection port (4). The resin raw material infiltrates the fiber (1) in the die. An ultrasonic transducer installed in the second section (32) applies lateral vibration, thereby accelerating the infiltration of the fiber (1) by the resin raw material. After the die is heated, the resin raw material reacts and solidifies. The composite material profile (7) is pulled out of the pultrusion die (3) under the pulling action of a pulling machine (6). The frequency of the ultrasonic transducer (5) is 20 kHz-75 kHz, and the pultrusion line speed is 0.3-1.5 m / min.

10. The method for forming an ultrasonically assisted fiber-reinforced pultruded thermosetting composite material according to claim 9, characterized in that: The frequency of the ultrasonic transducer (5) is 28 kHz-40 kHz, and a pulse mode is used.

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