Continuous fiber grid structure composite material and preparation method thereof

Abstract

The invention discloses a continuous fiber grid structure composite material and a preparation method thereof. The continuous fiber grid structure composite material is prepared by compounding silicon carbide fiber fabric and epoxy resin. The preparation method comprises the following steps: firstly, designing a spinning pattern using silicon carbide fibers and hot melting lines, heating the fiber cloth to melt the hot melting line grids, putting the fabric into a mold to be compounded with epoxy resin, sealing, injecting glue, curing and demolding to obtain the silicon carbide fiber composite material. Finally, the fiber grid composite material is prepared. According to the preparation method, the use amount of the silicon carbide fiber is reduced, and meanwhile, the prepared composite material has the characteristic of light weight, is excellent in mechanical property, has excellent properties such as wear resistance, corrosion resistance, oxidation resistance, high elastic modulus, high hardness and high-temperature strength, and can be applied to the fields of unmanned aerial vehicle main body component structures and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of composite materials, and in particular relates to a continuous fiber lattice structure composite material and a preparation method thereof. Background Art

[0002] As an important trend of current and future development, lightweight materials have attracted more and more attention and research from designers. Among them, an important way to lightweight UAVs is to use lightweight materials and optimize the design of lightweight materials. The original design resulted in excessive weight of aircraft components, resulting in a very low utilization rate of structural materials, so most of them have a large room for optimization and improvement. The unique physical and chemical properties of silicon carbide materials give it excellent properties such as wear resistance, corrosion resistance, oxidation resistance, high elastic modulus, high hardness and high temperature strength, and gradually replace metal as an important material for pressure sensors. However, the price of silicon carbide materials is still very expensive. If plate composite materials are used, the cost will be greatly increased, and it will bring unnecessary waste of resources.

[0003] In order to achieve the goal of lightweight while achieving high performance, the existing technology generally tends to use laser cutting technology to process flat composite materials. This technology can ensure the smoothness and precision of the cutting edge, reduce material waste, and optimize the structural layout of the material by finely controlling the cutting path and shape, thereby effectively reducing the weight of the composite material while maintaining or improving the overall performance. During the laser cutting process, the laser beam works in a non-contact manner, avoiding the heat-affected zone and mechanical stress that may be caused by traditional mechanical cutting, and ensuring the integrity of the internal structure of the composite material and the stability of its performance. However, the laser energy during laser cutting of flat composite materials will cause local heating of the material, forming a heat-affected zone, which will cause a decrease in material performance, such as reduced strength, weakened bonding between the fiber and the matrix, fiber breakage, resin loss, etc., and harmful gases such as carbon monoxide and carbon dioxide will also be produced during the laser cutting process, causing environmental pollution. Summary of the invention

[0004] The present invention is based on the inventor's discovery and understanding of the following facts and problems: using laser to cut a flat composite material to make it lightweight will cause the fiber of the flat composite material to break and the resin to be lost, resulting in a decrease in the mechanical properties of the lightweight composite fiber material.

[0005] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the present invention provides a continuous fiber grid structure composite material and a preparation method thereof. The present invention designs a continuous weaving method of a fiber grid fabric, which has evenly arranged grids after heating and curing, and does not need to use a laser to cut the flat composite material, thereby achieving the purpose of lightweight design.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The first object of the present invention is to provide a method for preparing a continuous fiber lattice structure composite material, which specifically comprises the following steps: Step 1, using yarn and hot melt thread to weave the grid fabric in an alternating cycle; Step 2, heating the grid fabric to melt the hot melt line, and then using a curing material to cure the grid fabric, thereby obtaining the continuous fiber grid structure composite material; Preferably, the yarns are silicon carbide fibers or carbon fibers.

[0007] Compared with the traditional method of preparing lightweight flat composite materials by laser cutting flat composite materials, the present invention designs a fabric weaving method that combines fabric fibers and hot melt lines, and realizes the purpose of adding through holes on the flat fabric to achieve lightweight materials during the fabric curing process. The method proposed by the present invention does not require the use of an additional laser cutter to cut flat composite materials, and will not cause the problems of large heat-affected zone, harmful gas emissions, and poor cutting effect caused by high material reflectivity caused by traditional laser cutting of flat composite materials. It also does not require additional laser cutters, which can reduce related preparation costs.

[0008] Preferably, step 1 includes the following steps: 1) First, use the yarn to continuously thread the reed to form a width of a The yarn is passed through the warp for weaving, and the hot melt wire is continuously inserted into the adjacent reeds, and then the hot melt wire is continued to be used to reed to form a width of b The hot-melt thread is woven through the warp, and then the yarn is continuously inserted into the reed adjacent to the hot-melt thread and the yarn is continuously reeded until a width of a The yarn is drawn through the warp to form a drawing-in and weaving cycle, and the drawing-in and weaving cycle is repeated several times; 2) First, use the yarn to insert and beat up the weft to form a width of c The yarn is woven through the harness, and then the hot melt thread is used to continuously insert and beat the weft to form a width of d The hot-melt thread is drawn through the harness to form a weaving cycle. The weaving of the fiber checkered fabric is completed by repeating the weaving cycle several times.

[0009] Preferably, the width of the yarn weaving c Drawing in the yarn for weaving a Twice the width of the hot melt thread weaving b Width of weaving with hot melt thread d equal.

[0010] Preferably, in step 2, curing the grid fabric is performed by the following method: heating the grid fabric to melt the hot melt line to form through holes, then laying it flat in a mold, injecting curing material, sealing, heating, and keeping warm before demoulding.

[0011] The curing material includes epoxy resin, polyester resin, phenolic resin or silicone resin.

[0012] Preferably, the curing material is a mixture of epoxy resin and curing agent, and the mass ratio of epoxy resin main agent to modified amine curing agent is 1:0.85. The modified amine curing agent comprises modified methyltetrahydrophthalic anhydride and tertiary amine. Before use, the epoxy resin and curing agent are first fully mixed, heated and kept warm, and then degassed in a vacuum low-pressure environment before being compounded with the grid fabric.

[0013] More preferably, the curing temperature is 90-110° C. and the curing time is 1-2 hours.

[0014] The second object of the present invention is to provide a continuous fiber lattice structure composite material, which is prepared by the above preparation method and has lattice holes, and the yarn has no breaks on the four sides of the lattice holes.

[0015] Preferably, the unit weight of the continuous fiber lattice structure composite material is 0.01-0.02 g / m 2 .

[0016] Preferably, the square holes are square, and the side length of the square holes is b , the distance between the near edges of two adjacent square holes is 2 a , b :2 a It is 10:9.

[0017] Specifically, in some embodiments of the present invention, the side length of the square holes is 2 cm, and the distance between the near sides of two adjacent square holes is 1.8 cm. This ratio balances the requirements of lightweight and mechanical properties of the composite material, and has the best mechanical properties and use effect.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for preparing a continuous fiber grid composite material, in which yarn and hot-melt wire are alternately woven in a circular manner to form a hot-melt wire grid, and evenly arranged grid holes are formed on the fiber fabric after heating. By adjusting the size and number of cycles of the warp and heddle drawing, grid fabrics with different parameters can be designed, which has good designability. At the same time, the grid four sides of the woven grid fabric do not have structural defects such as fiber fractures, and have excellent mechanical properties.

[0019] The continuous fiber lattice composite material prepared by the preparation method proposed in the present invention is formed by compounding the grid fabric with the polymer to form a continuous fiber lattice composite material with uniform lattice holes. Compared with the lattice hole edge formed by cutting, which produces a large number of broken fibers and forms structural defects, the lattice hole edge of the continuous fiber lattice composite material proposed in the present invention does not have fiber fractures, is a continuous fiber, has no defects, and has better mechanical properties. The present invention uses silicon carbide fiber or carbon fiber yarn to weave the continuous fiber lattice composite material, and the prepared continuous fiber lattice composite material has the characteristics of excellent mechanical properties, chemical stability and high temperature tolerance. In particular, silicon carbide fiber is a good conductive material that can absorb and transmit electromagnetic radiation. The continuous fiber lattice composite material prepared by silicon carbide fiber has more excellent high temperature resistance, corrosion resistance, strength, hardness and other mechanical properties. At the same time, the continuous fiber lattice composite material proposed in the present invention has a low density, which can realize its application in the field of lightweight, especially in the field of lightweight unmanned aerial vehicles. It has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of reed threading; Figure 2 It is a weaving schematic diagram; Figure 3 A schematic diagram of a mold for fixing the bottom of the grille fabric; Figure 4 It is a schematic diagram of a mold for fixing the shape of the grid; Figure 5 This is a schematic diagram of RTM curing; Among them: 1-1 is 60# reed, 1-2 is hot-melt wire, 1-3 is silicon carbide fiber; 2-1 is 60# reed tooth, 2-2 is weaving shaft, 2-3 is heald on the second heald frame, 2-4 is heald on the first heald frame; 5-1 is feed barrel, 5-2 is injection pipe, 5-3 is curing mold, 5-4 is discharge pipe, 5-5 is waste liquid collection barrel, 5-6 is vacuum pump interface. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0022] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0023] In the following examples, silicon carbide fiber was purchased from Zeralon RAF of Hunan Ze Rui New Materials Co., Ltd., with a length of 500m and a weight of 50g; JC-02A and JC-02B mixed epoxy resins were purchased from Changshu Jiafa Chemical Co., Ltd., JC-02A was the resin, and JC-02B was the curing agent (components were modified methyltetrahydrophthalic anhydride and tertiary amine); the hot melt thread was 150D nylon hot melt adhesive thread with a melting point of 85°C from Liuqing Sewing Thread Changshu Store; the remaining chemical reagents were all commercial reagents, analytically pure 99.9%, and were not further processed.

[0024] The present invention is further described in detail below in conjunction with the accompanying drawings: Example 1 See also Figure 1 In this embodiment, a continuous fiber lattice structure composite material is prepared by the following steps: Step 1, weaving the grille fabric: The reeding design is: use 60# reed teeth 1-1 for reeding, design fabric, reeding diagram Figure 1 , 11 silicon carbide yarns 1-3 are continuously inserted to reach the required weaving width of 0.9 cm, and the reeds of adjacent silicon carbide yarns are continuously inserted with hot melt wires, the purpose is to bind and fix the continuous silicon carbide fabric; the hot melt wires 1-2 are continuously inserted every two reeds, and the hot melt wires are repeatedly inserted 9 times, so that the grid part in the middle grid fabric reaches 2 cm, forming a weaving cycle of the grid fabric. After repeating 8 cycles, 22 silicon carbide fibers 1-3 are finally inserted to end the warp drawing process.

[0025] The drawing-in design is as follows: the healds of the front and rear heald frames 2-3 and 2-4 are used for drawing-in. The healds on one heald frame 2-3 and the healds on one heald frame 2-4 are grouped together, and the drawing-in is performed according to the group rule. Figure 2As shown, the healds on the first heald frame 2-3 are lifted up, and the healds on the second heald frame 2-4 are moved downward to form an opening. After the weft yarn is introduced for beating, the motor causes the healds on the first heald frame 2-3 to fall, and the healds on the second heald frame 2-4 are lifted up. After the opening is formed, the weft yarn is introduced to complete the interweaving process between the warp and weft yarns.

[0026] The weft insertion design is as follows: first, silicon carbide fiber is used for weft insertion and beating. Interweaving, the weft density is controlled to be 10 threads / cm, and the weft is beaten 18 times continuously. After the width reaches 1.8cm, hot melt thread is used for beating. Four weft hot melt threads are beaten first to fix the silicon carbide fiber. Using the machine's warp winding tool, after the heald frame moves forward 1cm, four weft hot melt threads are beaten continuously; after the heald frame moves forward 6mm, four weft hot melt threads are beaten to complete the weft yarn weaving of the grid part of the grid fabric.

[0027] The combination of silicon carbide fiber and hot melt wire constitutes a weaving cycle of the grid fabric. After 9 consecutive weaving cycles, the fabric reaches 30cm×30cm, completing the weaving process of the fabric. The woven fabric is as follows Figure 3 shown.

[0028] Step 2, curing mold pretreatment: like Figure 4 As shown, the curing mold has 64 small square iron blocks of 20mm×20mm×9.7mm and a set of 320mm×320mm×5.0mm upper grid mold and lower grid mold, and the upper grid mold and the lower grid mold can be buckled and fixed.

[0029] Wipe the surface of the solidified mold with a release agent for more than three times in one direction, with an interval of 15-20 minutes each time, then soak the solidified mold in an aliphatic hydrocarbon release agent for 2-3 minutes, take it out and dry it for easy demoulding. Apply a thin layer of 3M epoxy structural adhesive DP460 on a square surface of the small square iron block and fix it to the surface of the lower mold of the grid.

[0030] Step 3, Curing the Grid Fabric: Fabric laying: put the grid fabric into the oven and heat it at 60℃ for 10 minutes to completely melt the hot melt line. Then, according to the placement of the small squares, place the melted grid fabric flatly in the mold cavity, so that the small squares pass through the grid fabric without wrinkles, and trim off the excess scraps; Resin pretreatment: After fully mixing the resin main agent JC-02A and the curing agent JC-02B at a mass ratio of 1:0.85, heat them in an oven at 60°C for 30 minutes to remove large bubbles first, and then put them in a vacuum drying oven at 60°C and 0.1Mpa for degassing for 2 hours.

[0031] Mould closing: Figure 5As shown, the feed barrel 5-1 is connected to the curing mold 5-3 by using an injection pipe 5-2, and the outlet of the curing mold is connected to the waste liquid collection barrel 5-5 through the exhaust pipe 5-4, and the waste liquid collection barrel 5-5 is connected to the vacuum pump interface 5-6. Add the treated JC-02A epoxy resin and curing agent mixture into the feed barrel 5-1; Resin injection: Then inject it from the resin injection port of the curing mold, and control the injection pressure at about 0.1Mpa until there is no bubble flowing out of the outlet, and then stop injecting; Curing: Place the mold in a large oven for temperature-controlled curing at 90°C for 2 hours; Demoulding: Separate the upper grid mould and the lower grid mould, and remove the grid fabric from the mould to obtain a fiber grid structure composite material.

[0032] Example 2 Step 1, weaving the grille fabric: The grid fabric is woven using carbon fiber and hot-melt yarn, and the weaving process is the same as that of Example 1.

[0033] Step 2, mold pretreatment: The processing process is the same as in Example 1.

[0034] Step 3, curing the woven fabric: 1) Put the grid fabric into the oven and heat it at 60℃ for 10 minutes to completely melt the hot melt line. Then, according to the placement of the small squares, place the melted grid fabric flatly in the mold cavity, so that the small squares pass through the grid fabric without wrinkles, and trim off the excess scraps; 2) After fully mixing the resin main agent JC-02A and the curing agent JC-02B at a mass ratio of 1:0.85, heat them in an oven at 60°C for 30 minutes to remove large bubbles first, and then put them in a vacuum drying oven at 60°C and 0.1Mpa for degassing for 2 hours; 3) If Figure 5 As shown, the feed barrel 5-1 is connected to the curing mold 5-3 using an injection pipe 5-2, and the outlet of the curing mold is connected to the waste liquid collection barrel 5-5 through the exhaust pipe 5-4, and the waste liquid collection barrel 5-5 is connected to the vacuum pump interface 5-6, and the treated mixed liquid of JC-02A epoxy resin and curing agent is added to the feed barrel 5-1. The mixed liquid of JC-02A epoxy resin and curing agent is injected from the resin injection port of the curing mold, and the injection pressure is controlled at about 0.1Mpa until no bubbles flow out of the outlet, and the injection is stopped; 4) Place the mold in a large oven for temperature-controlled curing at 110°C for 1 hour; 5) Separating the upper grid mold and the lower grid mold, removing the grid fabric from the mold, and removing excess resin film to obtain a fiber grid structure composite material.

[0035] The unit mass of the continuous fiber lattice structure composite material prepared in Example 1 and Example 2 is 0.01-0.02 g / m 2 .

[0036] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a continuous fiber lattice structure composite material, characterized in that: The following steps are involved: Step 1, using yarn and hot melt thread to weave the grid fabric in an alternating cycle; Step 2, heating the grid fabric to melt the hot melt line, and then using a curing material to cure the grid fabric, so as to obtain the continuous fiber grid structure composite material.

2. The method for preparing the continuous fiber lattice structure composite material according to claim 1, characterized in that: The yarn is silicon carbide fiber or carbon fiber.

3. The method for preparing the continuous fiber lattice structure composite material according to claim 1 or 2, characterized in that: In step 1: 1) First, use the yarn to continuously thread the reed to form a width of a The yarn is passed through the warp for weaving, and the hot melt wire is continuously inserted into the adjacent reeds, and then the hot melt wire is continued to be used to reed to form a width of b The hot-melt thread is woven through the warp, and then the yarn is continuously inserted into the reed adjacent to the hot-melt thread and the yarn is continuously reeded until a width of a The yarn is drawn through the warp to form a drawing-in and weaving cycle, and the drawing-in and weaving cycle is repeated several times; 2) Use yarn for weft insertion and beating to form a width of c The yarn is woven through the harness, and then the hot melt thread is used to continuously insert and beat the weft to form a width of d The hot-melt thread is drawn through the harness for weaving, which is a drawing-in weaving cycle. The drawing-in weaving cycle is repeated several times to complete the weaving of the fiber checkered fabric.

4. The method for preparing the continuous fiber lattice structure composite material according to claim 3, characterized in that: Width of yarn drawn into weaving c Threading the yarn for weaving a Twice the width of the hot melt thread weaving b Width of weaving with hot melt thread d equal.

5. The method for preparing the continuous fiber lattice structure composite material according to claim 1, characterized in that: In the step 2, the grid fabric is heated to melt the hot melt lines to form through holes, and then laid flat in a mold and injected with curing material, and then sealed, heated, and kept warm before demoulding to obtain the fiber grid composite material.

6. The method for preparing the continuous fiber lattice structure composite material according to claim 5, characterized in that: The curing temperature is 90-110° C., and the curing time is 1-2 hours.

7. The method for preparing a continuous fiber lattice structure composite material according to claim 1, characterized in that: The curing material comprises epoxy resin, polyester resin, phenolic resin or silicone resin.

8. A continuous fiber lattice structure composite material obtained by the preparation method according to any one of claims 1 to 7, characterized in that: The invention has square through holes, and the yarn has no breaks on the four sides of the square through holes.

9. The continuous fiber lattice structure composite material according to claim 8, characterized in that: Unit weight is 0.01~0.02g / m 2 .

10. The continuous fiber lattice structure composite material according to claim 8, characterized in that: The ratio of the side length of the square through holes to the distance between the near sides of two adjacent square through holes is 10:9.

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