Preparation method of carbon fiber felt reinforced composite material

Abstract

The present invention relates to the technical field of composite materials, and particularly relates to a preparation method of a carbon fiber felt reinforced composite material, comprising the following steps: S1. Surface ion etching treatment is respectively carried out on thermoplastic material fiber filaments and sized continuous carbon fiber yarns, and the treated thermoplastic material fiber filaments and the sized continuous carbon fiber yarns are woven to obtain a mixed woven plain fabric; S2. Using the mixed woven plain fabric as a base layer and carbon fiber pre-oxidized short fibers as fillers, a carbon fiber reinforced thermoplastic material composite felt sheet is obtained through needling treatment; S3. After the carbon fiber reinforced thermoplastic material composite felt sheet and a thermoplastic material film are alternately laminated and laid, hot pressing is carried out to form a carbon fiber felt reinforced composite material; The carbon fiber felt reinforced thermoplastic composite material prepared by the method of the present invention has high toughness and interfacial strength.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and particularly relates to a preparation method of a carbon fiber felt reinforced composite material. Background Art

[0002] The carbon fiber modified reinforced composite material is a new type of material with light weight and high strength. It combines the excellent properties of carbon fiber felt with the processing properties of thermoplastic resin, and has characteristics such as high strength, high modulus, low density, corrosion resistance, wear resistance, fatigue resistance, electrical conductivity, and thermal conductivity. This composite material is widely used in the fields of aerospace, automotive, sports goods, building materials, etc. In recent years, the manufacturing of carbon fiber composite materials has provided harder and lighter alternatives to traditional metal components. In the automotive industry, the application of carbon fiber reinforced composite materials is becoming more and more extensive.

[0003] Traditional preparation methods of felt composite materials mainly include melt mixing method, solution mixing method, powder mixing method, etc. The melt mixing method is to mix carbon fiber felt and thermoplastic resin at high temperature, and then form them through processes such as extrusion, injection or pressing. The solution mixing method is to soak carbon fiber felt in a solution containing thermoplastic resin, and then remove the solvent through processes such as evaporation and drying to prepare a composite material. The powder mixing method is to mix carbon fiber felt with thermoplastic resin powder, and then prepare a composite material through processes such as heating and pressing. Most of these methods have defects such as uneven resin distribution, poor pre-impregnation effect, and weak interfacial bonding force, which greatly affect the performance of the material. Summary of the Invention

[0004] In order to solve the technical problems of uneven resin dispersion, poor pre-impregnation effect, and weak interfacial bonding force existing in the preparation process of the composite material in the prior art, a preparation method of a carbon fiber felt reinforced composite material is provided. The composite material obtained by the method of the present invention has a relatively high interfacial strength and good overall mechanical properties.

[0005] In order to achieve the above object, the present invention is realized through the following technical solutions:

[0006] A preparation method of a carbon fiber felt reinforced composite material, comprising the following steps:

[0007] S1. Respectively perform surface ion etching treatment on thermoplastic material filaments and sizeless continuous carbon fiber yarns, and braid the treated thermoplastic material filaments and the sizeless continuous carbon fiber yarns to obtain a mixed woven plain fabric;

[0008] S2. Using the mixed woven plain fabric as a base layer and carbon fiber pre-oxidized fiber short fibers as fillers, obtain a carbon fiber reinforced thermoplastic material composite felt sheet through needling treatment;

[0009] S3. After interleaving and laminating the carbon fiber reinforced thermoplastic composite felt sheet and the thermoplastic material film, hot press molding is carried out to obtain a carbon fiber felt reinforced composite material.

[0010] Further, the thermoplastic material fiber filaments are selected from one or more of PAEK fibers, PPS fibers, TPI fibers, PEI fibers, and PPSU fibers; the PAEK fibers are selected from one or more of PEEK fibers, PEK fibers, PEKK fibers, PEEKK fibers, and PEKEKK fibers; the diameter range of the fiber filaments is between 0.2 and 0.8 mm.

[0011] The size of the sized carbon fiber yarn is 1K to 6K, and the width is at least 1 mm.

[0012] The thermoplastic material film is selected from one or more of PAEK films, PPS films, TPI films, PEI films, and PPSU films; the PAEK films are selected from one or more of PEEK films, PEK films, PEKK films, PEEKK films, and PEKEKK films; the film thickness range is between 0.05 and 0.2 mm.

[0013] The sized continuous carbon fiber yarn is a carbonized continuous carbon fiber yarn that has not been treated with a sizing agent, especially not treated with a thermosetting sizing agent. Using unsized carbon fiber can eliminate the influence of high-temperature desizing oxidation on the strength of the continuous carbon fiber yarn, eliminate the waste of energy due to high-temperature heating, eliminate the environmental pollution caused by the volatilization of gas tar formed by high-temperature pyrolysis, and eliminate the influence of incomplete treatment on the mechanical properties and quality of the composite material. The more the residual amount of the thermosetting sizing agent, the more serious the influence on the performance and quality, and the mechanical strength shows a downward trend.

[0014] Further, the weaving is a plain weave with the sized continuous carbon fiber yarn as the weft and thermoplastic fibers and sized continuous carbon fibers arranged evenly at intervals as the warp. In the warp, the number ratio of thermoplastic fibers to sized continuous carbon fibers is 1:1 - 2, and the number ratio of the weft to the warp is 2 - 5:1.

[0015] Or the thermoplastic material fiber filaments and the continuous carbon fiber yarn are combined into strands in proportion and then used as single yarns for plain weaving.

[0016] The proportion of continuous carbon fibers in the mixed plain weave fabric is 50 - 80 wt%. A rapier loom can be used for weaving. The thermoplastic material fiber filaments in the weft direction can supplement the total amount of resin in the subsequent pre-impregnation, improve the pre-impregnation effect of the thermoplastic material on the carbon fiber, and reduce the influence of poor pre-impregnation quality and low mechanical properties caused by the ineffective penetration of the additional layer of resin material. The continuous carbon fiber yarn in the warp direction can endow the felt reinforced composite material with a higher unidirectional load-bearing capacity and better mechanical properties.

[0017] Furthermore, the surface ion etching treatment is carried out by using a vacuum plasma device. The internal plasma nozzle is 5-8 mm away from the material surface, the plasma excitation frequency is 25 KHz, the power during treatment is 500-3000 W, the gas used during treatment is nitrogen or helium, the gas flow rate during treatment is 50-200 L / min, and the treatment time is 1-10 min. For thermoplastic material fibers, the ion etching treatment causes the chemical bonds in the molecular chain segments on the material surface to break through high-speed charged ions, and reacts with plasma free radicals, thereby improving the surface activity of carbon fibers; at the same time, it has an etching effect, forming many fine pits and grooves on the surface of carbon fibers, increasing the specific surface area of the carbon fiber surface, improving the composite pre-impregnation effect and quality with thermoplastic materials, and thus improving the interfacial performance and comprehensive mechanical properties.

[0018] Still further, the surface ion etching treatment is a continuous treatment, including the processes of unwinding, ion etching, cleaning, drying, and winding. Unwinding and winding are carried out simultaneously for multiple bundles of thermoplastic material fibers and continuous carbon fiber yarns. They pass through multiple tension rollers at different heights, and the width of each bundle of yarns is expanded and the surface tension is evenly adjusted to lay a foundation for subsequent uniform treatment; the unwinding speed is 1-10 m / min; the material after ion etching treatment enters the solution tank evenly for continuous cleaning treatment, which is carried out by soaking in an ethanol solution, and can remove the material foam generated by the ion etching treatment, eliminating the adverse effects on the composite pre-impregnation effect and surface quality; drying is carried out by a semi-closed drying tunnel type high-temperature heating furnace. The total length of the heating furnace is 1 m, and the set temperature is 120 °C, which can effectively remove the residual ethanol solution in the material.

[0019] Furthermore, the thermoplastic material film is a film obtained by stretching after melt extrusion. The processing temperature range for melt extrusion is between 300-420 °C, and it is longitudinally stretched with a stretching ratio of 1.1-1.8 times, and the processing temperature during stretching is 240-320 °C;

[0020] Further, the steps of the hot pressing and forming are as follows: on the cavity sealing plate of the mold and the PI isolation film, first coat the high-temperature release agent 2-3 times, with an interval of 5-8 minutes between each coating, to prepare for mold loading; stack the carbon fiber reinforced thermoplastic composite felt sheet and the thermoplastic film in an alternating manner, and place the coated PI isolation film on the upper and lower outer surfaces of the stacked materials, and then move them into the mold together; close the mold on the hot pressing equipment, maintain it at a cold pressure of 3 MPa for 20 minutes, adjust to 1 MPa for pre-pressing, then heat up to 260-330 °C, keep the temperature for 20-40 minutes after reaching the temperature, then heat up to 320-400 °C, stop heating after reaching the temperature, then pressurize to 4-8 MPa at a rate of increasing 1 MPa every 8 minutes, and then pressurize to 12-20 MPa at a rate of increasing 1 MPa every 5 minutes. After the displayed temperature naturally cools to 220-260 °C, quickly cool it down through an external cooling device, with a cooling rate of about 3-6 °C / min. After the temperature drops below 140 °C, demold to obtain the product.After the coated high-temperature release agent dries, an anti-sticking layer will be formed on the surface of the cavity sealing plate and the PI isolation film. Coating at intervals of 5-8 minutes is to ensure that the high-temperature release agent dries completely. Coating 2-3 times is to form multiple anti-sticking layers to prevent the adhesion of excess overflowing TPI resin in places where the coating is not in place. The coating of the cavity sealing plate is to prevent the adhesion of excess TPI resin, and the PI isolation film is used to isolate the cavity sealing plate from the product, which can prevent the abnormal defects on the surface of the cavity sealing plate from affecting the quality of the product plate surface. At the same time, the coating of the PI isolation film is easy to separate from the plate; maintaining at 3 MPa cold pressure for 20 minutes is to discharge the air between the laminates; a pre-pressure of 1 MPa can make the stacked materials more dense and the heat transfer efficiency higher; heating in the 260-330 °C section first can improve the uniformity of the mold temperature, thereby improving the overall melting effect of the thermoplastic material, so that the temperature of each part of the mold can reach the composite temperature of 320-400 °C evenly and quickly in the subsequent 320-400 °C section; after stopping heating, natural cooling and pressurization start. The pressurization in the first stage is carried out at a rate of 1 MPa / 8 minutes each time. Multiple small pressures can weaken the high-speed impact of the TPI resin melt on the modified carbon fiber fabric, reduce the tension between carbon fiber bundles, and the probability of carbon fiber slippage and wrinkling. At the same time, multiple pressurizations can make the TPI melt fully infiltrate the modified carbon fiber and improve the infiltration quality; the pressurization in the second stage is carried out at a rate of 1 MPa / 5 minutes each time. Using high pressure makes the composite material more dense and the internal voids lower, and the interfacial bonding strength between the TPI resin and the modified carbon fiber fabric increases significantly; after the subsequent pressure reaches 12-20 MPa, heating is stopped and it is allowed to cool naturally (maintaining the natural cooling state). When the temperature drops to 220-260 °C, which is significantly lower than the heat distortion temperature of the thermoplastic material, the composite material gradually becomes stable inside, and subsequent rapid cooling to below 140 °C for demolding all restrict the movement of resin molecular chains, reduce the occurrence of defects such as deformation and warping, and at the same time can also reduce the internal stress generated due to the inconsistent shrinkage of carbon fiber and resin materials, improving the overall mechanical properties of the composite material.

[0021] Further, the carbon fiber felt-reinforced composite material, calculated according to 100% by weight, includes: continuous carbon fiber accounting for 35-50 wt%, carbon fiber pre-oxidized staple fiber accounting for 10-18%, and the balance being thermoplastic material. The source of the thermoplastic material is thermoplastic material fiber filaments and thermoplastic material films; the pre-oxidized staple fiber has good toughness, has an obvious effect on improving the overall mechanical properties of the composite material, and at the same time imparts good flame retardancy, heat insulation, and high-temperature resistance characteristics to the composite material.

[0022] Beneficial technical effects:

[0023] The present invention uses surface ion etching treatment to trigger the breakage of chemical bonds in the molecular chain segments on the surfaces of thermoplastic material fibers and continuous carbon fibers, generating free radical active sites, thereby improving the adhesion strength between the thermoplastic material and the carbon fibers, improving the surface properties of the material while enhancing the bonding force between the thermoplastic material matrix and the carbon fibers;

[0024] The use of sized continuous carbon fiber yarns in the present invention can avoid the influence of high-temperature desizing oxidation on the strength of continuous carbon fiber yarns, reduce energy waste, reduce environmental pollution, and improve the mechanical properties of composite materials. Mixing and weaving them with thermoplastic material fibers to form a plain weave fabric, and the plain weave structure helps to improve the impregnation effect of the thermoplastic material on continuous carbon fibers, making the carbon fiber distribution uniform and stable, thereby improving the mechanical properties of the composite material; In addition, using chopped carbon fiber pre-oxidized filaments to needle-fill the gaps of the mixed plain weave fabric enhances the interfacial strength of the composite material and improves the overall mechanical properties;

[0025] The present invention adopts precise hot pressing forming control technology, and elaborates on the pressure and temperature control strategies during the hot pressing forming process, including key steps such as cold pressure pre-compaction, staged pressure increase, and rapid cooling and temperature reduction, ensuring the uniformity of the internal structure of the composite material and the maximization of the interfacial bonding strength;

[0026] Through the comprehensive application of the above innovation points, the carbon fiber felt reinforced thermoplastic composite material prepared by the inventive method has higher mechanical properties, including tensile strength, impact resistance, and high-temperature resistance, etc. Detailed Description of the Invention

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way restricts the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0028] Unless otherwise specifically stated, the numerical values set forth in these embodiments do not limit the scope of the present invention. Technologies and methods known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the said technologies and methods should be regarded as part of the specification. In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0029] In the following examples, the experimental methods without specific conditions are usually determined according to national standards; if there is no corresponding national standard, they are carried out according to general standard requirements or general methods.

[0030] Preparation Example 1

[0031] This example is for the preparation of a mixed plain weave fabric:

[0032] The PEEK fibers (continuous filaments, monofilament diameter 0.5 mm, provided by Junhua Co., Ltd.) are subjected to continuous surface ion etching treatment. The specific process is unwinding (speed 4 m / min), ion etching, cleaning, drying, and winding. Among them, ion etching is carried out using a vacuum plasma device. The internal plasma nozzle is 20 mm away from the material surface, the plasma excitation frequency is 25 KHz, the power during treatment is 2000 W, the gas used during treatment is nitrogen, the gas flow rate during treatment is 180 L / min, and the treatment time is 2 min. The material after ion etching uniformly enters a solution tank containing ethanol for continuous cleaning treatment, and then undergoes treatment in a semi-closed tunnel-type high-temperature heating furnace. The total length of the heating furnace is 1 m, and the set temperature is 120 °C for drying.

[0033] The non-sized continuous carbon fiber yarns (continuous filaments, monofilament width 3 mm, provided by Jiangsu Hengshen Co., Ltd.) are subjected to continuous surface ion etching treatment. The specific process is unwinding at a speed of 2 m / min, ion etching, cleaning, drying, and winding. Among them, ion etching is carried out using a vacuum plasma device. The internal plasma nozzle is 8 mm away from the material surface, the plasma excitation frequency is 25 KHz, the power during treatment is 3000 W, the gas used during treatment is nitrogen, the gas flow rate during treatment is 260 L / min, and the treatment time is 2 min. The material after ion etching uniformly enters a solution tank containing ethanol for continuous cleaning treatment, and then undergoes treatment in a semi-closed tunnel-type high-temperature heating furnace. The total length of the heating furnace is 1 m, and the set temperature is 120 °C for drying.

[0034] After the above surface ion etching treatment, 180 PEEK fibers and 180 non-sized continuous carbon fiber yarns are selected and evenly distributed at intervals as warp threads, and 1500 non-sized continuous carbon fiber yarns are used as weft threads for plain weaving. After weaving, a CCF / PEEK mixed plain weave fabric (size 5 m * 600 mm * 0.5 mm) is obtained, and the CCF content in the fabric is 78 wt%.

[0035] Preparation Example 2

[0036] The PPSU fiber (continuous filament, monofilament diameter 0.25 mm, provided by Junhua Co., Ltd.) is subjected to continuous surface ion etching treatment. The specific process is unwinding (speed 6 mm / min), ion etching, cleaning, drying, and winding. Among them, ion etching is carried out using a vacuum plasma device. The internal plasma nozzle is 10 mm away from the material surface, the plasma excitation frequency is 25 KHz, the power during treatment is 1200 W, the gas used during treatment is nitrogen, the gas flow rate during treatment is 180 L / min, and the treatment time is 3 min. The material after ion etching uniformly enters a solution tank containing ethanol for continuous cleaning treatment, and then undergoes treatment in a semi-closed drying oven type high-temperature heating furnace. The total length of the heating furnace is 1 m, and the set temperature is 120 °C for drying.

[0037] The non-sized continuous carbon fiber yarn (continuous filament, monofilament width 5 mm, provided by Jiangsu Hengshen Co., Ltd.) is subjected to continuous surface ion etching treatment. The specific process is unwinding (speed 4 mm / min), ion etching, cleaning, drying, and winding. Among them, ion etching is carried out using a vacuum plasma device. The internal plasma nozzle is 8 mm away from the material surface, the plasma excitation frequency is 25 KHz, the power during treatment is 2300 W, the gas used during treatment is nitrogen, the gas flow rate during treatment is 250 L / min, and the treatment time is 3 min. The material after ion etching uniformly enters a solution tank containing ethanol for continuous cleaning treatment, and then undergoes treatment in a semi-closed drying oven type high-temperature heating furnace. The total length of the heating furnace is 1 m, and the set temperature is 120 °C for drying.

[0038] After the above surface ion etching treatment, 160 PEEK fibers and 150 non-sized continuous carbon fiber yarns are evenly spaced and distributed as the warp, and 1500 non-sized continuous carbon fiber yarns are used as the weft for plain weaving. After weaving, a CCF / PPSU mixed plain fabric (size 5 m * 600 mm * 0.5 mm) is obtained, and the CCF content in the fabric is 74 wt%.

[0039] Preparation Example 3

[0040] The PPS fiber (continuous filament, monofilament diameter 0.5 mm, provided by Junhua Co., Ltd.) is subjected to continuous surface ion etching treatment. The specific process is unwinding (speed 4 m / min), ion etching, cleaning, drying, and winding. Among them, ion etching is carried out using a vacuum plasma device. The internal plasma nozzle is 15 mm away from the material surface, the plasma excitation frequency is 25 KHz, the power during treatment is 2200 W, the gas used during treatment is nitrogen, the gas flow rate during treatment is 220 L / min, and the treatment time is 2 min. The material after ion etching uniformly enters a solution tank containing ethanol for continuous cleaning treatment, and then undergoes treatment in a semi-closed drying oven type high-temperature heating furnace. The total length of the heating furnace is 1 m, and the set temperature is 120 °C for drying.

[0041] The continuous surface ion etching treatment was carried out on the sized continuous carbon fiber yarn (continuous filament, monofilament width 3 mm, provided by Jiangsu Hengshen Co., Ltd.). The specific process steps were unwinding (speed 2 m / min), ion etching, cleaning, drying, and winding. Among them, ion etching was carried out using a vacuum plasma device. The distance between the internal plasma nozzle and the material surface was 8 mm, the plasma excitation frequency was 25 KHz, the power during treatment was 3000 W, the gas used during treatment was nitrogen, the gas flow rate during treatment was 260 L / min, and the treatment time was 2 min. After ion etching, the material was evenly fed into a solution tank containing ethanol for continuous cleaning treatment, and then passed through a semi-closed tunnel-type high-temperature heating furnace for drying. The total length of the heating furnace was 1 m, and the set temperature was 120 °C for drying.

[0042] After the above surface ion etching treatment, 180 PEEK fibers and 180 sized continuous carbon fiber yarns were evenly distributed as warp threads, and 1500 sized continuous carbon fiber yarns were used as weft threads for plain weaving. After weaving, a CCF / PPS mixed plain fabric (size 5 m * 600 mm * 0.5 mm) was obtained, and the CCF content in the fabric was 78 wt%.

[0043] Preparation Example 4

[0044] The continuous surface ion etching treatment was carried out on PPS fibers (continuous filament, monofilament diameter 0.5 mm, provided by Junhua Co., Ltd.). The specific process steps were unwinding (speed 4 m / min), ion etching, cleaning, drying, and winding. Among them, ion etching was carried out using a vacuum plasma device. The distance between the internal plasma nozzle and the material surface was 15 mm, the plasma excitation frequency was 25 KHz, the power during treatment was 2200 W, the gas used during treatment was nitrogen, the gas flow rate during treatment was 220 L / min, and the treatment time was 2 min. After ion etching, the material was evenly fed into a solution tank containing ethanol for continuous cleaning treatment, and then passed through a semi-closed tunnel-type high-temperature heating furnace for drying. The total length of the heating furnace was 1 m, and the set temperature was 120 °C for drying.

[0045] The continuous surface ion etching treatment is carried out on the sizeless continuous carbon fiber yarn (continuous filament, single filament width 3 mm, produced by Weihai Guangwei Composite Materials Co., Ltd.). The specific process is unwinding (speed 4 m / min), ion etching, cleaning, drying, and winding. Among them, ion etching is carried out by using a vacuum plasma device. The internal plasma nozzle is 10 mm away from the material surface, the plasma excitation frequency is 25 KHz, the power during treatment is 2700 W, the gas used during treatment is nitrogen, the gas flow rate during treatment is 270 L / min, and the treatment time is 3 min. After ion etching, the material uniformly enters the solution tank containing ethanol for continuous cleaning treatment, and then passes through a semi-closed drying furnace for high-temperature heating treatment. The total length of the drying furnace is 1 m, and the set temperature is 120 °C for drying.

[0046] After the above surface ion etching treatment, 260 PPS fibers and 260 sizeless continuous carbon fiber yarns are combined into one strand of mixed yarn, and plain weaving is carried out with the single-strand mixed yarn as the weft and warp. After weaving, a CCF / PPS mixed plain fabric (size 5 m * 500 mm * 0.7 mm) is obtained, where the proportion of CCF in the fabric is 82 wt%.

[0047] Example 1

[0048] A preparation method of a carbon fiber felt reinforced composite material includes the following steps:

[0049] S1. Prepare the CCF / PEEK mixed plain fabric of Preparation Example 1;

[0050] S2. Using the CCF / PEEK mixed plain fabric as the base layer and carbon fiber pre-oxidized staple fibers (diameter 1 mm, aspect ratio 20) as the filler, through needle punching treatment, a carbon fiber reinforced thermoplastic composite felt sheet (thickness 0.7 mm) is obtained, where the weight proportion of the carbon fiber pre-oxidized staple fibers in the composite felt sheet is 10 wt%;

[0051] S3. Prepare a PEEK film. Melt the PEEK pure resin at a processing temperature of 350 - 390 °C, extrude and cast, and conduct longitudinal stretching with a stretching ratio of 1.3. The temperature of the rollers passed through during stretching is 200 - 280 °C to obtain a PEEK film with a thickness of 0.1 mm;

[0052] Hot pressing and forming: On the cavity sealing plate and PI isolation film of the mold, first coat 2 - 3 times of high-temperature release agent, with an interval of 5 - 8 min for each coating, to carry out the preparatory work before mold loading;

[0053] Stack the carbon fiber reinforced thermoplastic composite felt sheet and the PEEK film alternately in layers (a total of 41 layers, 20 layers of composite felt sheet and 21 layers of PEEK film), and place the coated PI isolation film on the upper and lower outer surfaces of the stacked materials, and move them into the mold together;

[0054] Close the mold on the hot pressing equipment, maintain it under a cold pressure of 3 MPa for 20 min, adjust it to 1 MPa for pre-pressing, then raise the temperature to 320 °C, keep the temperature for 30 min after reaching the temperature, raise the temperature to 380 °C again, stop heating after reaching the temperature, then pressurize it to 6 MPa at an increase of 1 MPa every 8 min, and then pressurize it to 18 MPa at an increase of 1 MPa every 5 min. After the displayed temperature naturally cools to 250 °C, rapidly cool it down through an external cooling device at a cooling rate of about 5 °C / min. After the temperature drops below 140 °C, demold to obtain a carbon fiber felt reinforced composite material product.

[0055] In the product of this case: the proportion of continuous carbon fiber is 42 wt%, the proportion of carbon fiber pre-oxidized short fiber is 10 wt%, and the proportion of PEEK is 48 wt%.

[0056] Example 2

[0057] A preparation method of a carbon fiber felt reinforced composite material, comprising the following steps:

[0058] S1. Prepare the CCF / PPSU woven plain fabric of Preparation Example 2;

[0059] S2. Use the CCF / PPSU woven plain fabric as the base layer and carbon fiber pre-oxidized short fibers (diameter 3 mm, aspect ratio 10) as the filler, and obtain a carbon fiber reinforced thermoplastic composite felt sheet (thickness 0.6 mm) through needling treatment, wherein the weight proportion of the carbon fiber pre-oxidized short fibers in the composite felt sheet is 14 wt%;

[0060] S3. Prepare a PPSU film, melt the PPSU pure resin at a processing temperature of 330 - 370 °C, extrude and cast and perform longitudinal stretching with a stretching ratio of 1.5, and the temperature of the rollers passed through during stretching is 200 - 260 °C to obtain a PPSU film with a thickness of 0.12 mm;

[0061] Hot pressing and forming: On the cavity sealing plate and PI isolation film of the mold, first coat the high-temperature release agent 2 - 3 times with an interval of 5 - 8 min each time to prepare for mold loading;

[0062] Stack the carbon fiber reinforced thermoplastic composite felt sheet and the PPSU film in an alternating layer-by-layer manner (a total of 43 layers, 21 layers of composite felt sheet and 22 layers of PPSU film), and place the coated PI isolation film on the upper and lower outer surfaces of the stacked materials, and move them into the mold together;

[0063] Close the mold on the hot pressing equipment, maintain at a cold pressure of 3 MPa for 20 min, adjust to 1 MPa for pre-pressing, then heat up to 280 °C, keep the temperature for 20 min after reaching the temperature, then heat up to 360 °C, stop heating after reaching the temperature, and then press at a rate of increasing 1 MPa every 8 min until 8 MPa, and then press at a rate of increasing 1 MPa every 5 min until 16 MPa. After the displayed temperature naturally cools to 280 °C, rapidly cool it down through an external cooling device, with a cooling rate of about 8 °C / min. After the temperature drops below 200 °C, demold to obtain a carbon fiber felt reinforced composite material product.

[0064] In the product of this case: the proportion of continuous carbon fiber is 44 wt%, the proportion of carbon fiber pre-oxidized short fiber is 13 wt%, and the proportion of PPSU is 43 wt%.

[0065] Example 3

[0066] A preparation method of a carbon fiber felt reinforced composite material, comprising the following steps:

[0067] S1. Prepare the CCF / PPS woven plain fabric of Preparation Example 3;

[0068] S2. Using the CCF / PPS woven plain fabric as the base layer and carbon fiber pre-oxidized short fibers (diameter 3 mm, aspect ratio 15) as the filler, obtain a carbon fiber reinforced thermoplastic composite felt sheet (thickness 0.6 mm) through needling treatment, wherein the weight proportion of the carbon fiber pre-oxidized short fibers in the composite felt sheet is 12 wt%;

[0069] S3. Prepare a PPS film, melt the PPS pure resin at a processing temperature of 330 - 370 °C, extrude and cast and conduct longitudinal stretching, with a stretching ratio of 1.2, and the temperature of the rollers passed through during stretching is 200 - 260 °C, to obtain a PPS film with a thickness of 0.08 mm;

[0070] Hot pressing and forming: On the cavity sealing plate and PI isolation film of the mold, first coat the high-temperature mold release agent 2 - 3 times, with an interval of 5 - 8 min for each coating, and conduct the pre-molding preparation work;

[0071] Stack the carbon fiber reinforced thermoplastic composite felt sheet and the PPS film alternately in layers (a total of 45 layers, 22 layers of composite felt sheet and 23 layers of PPS film), place the coated PI isolation film on the upper and lower outer surfaces of the laminated materials, and move them into the mold together;

[0072] Close the mold on the hot pressing equipment, maintain it under a cold pressure of 3 MPa for 20 min, adjust to 1 MPa for pre-pressing, raise the temperature to 320 °C, stop heating after reaching the temperature, then increase the pressure by 1 MPa every 8 min until 4 MPa, and then increase the pressure by 1 MPa every 5 min until 12 MPa. After the displayed temperature naturally cools to 240 °C, rapidly cool it down through an external cooling device at a cooling rate of about 5 °C / min. After the temperature drops below 140 °C, demold to obtain a carbon fiber felt-reinforced composite material product.

[0073] In the product of this case: the proportion of continuous carbon fiber is 50 wt%, the proportion of carbon fiber pre-oxidized short fiber is 12 wt%, and the proportion of PPS is 38 wt%.

[0074] Example 4

[0075] A preparation method of a carbon fiber felt-reinforced composite material, comprising the following steps:

[0076] S1. Prepare the CCF / PPS woven plain fabric of Preparation Example 4;

[0077] S2. Use the CCF / PPS woven plain fabric as the base layer and carbon fiber pre-oxidized short fibers (diameter 5 mm, aspect ratio 20) as the filler, and obtain a carbon fiber-reinforced thermoplastic composite felt sheet (thickness 0.7 mm) through needling treatment, wherein the weight proportion of the carbon fiber pre-oxidized short fibers in the composite felt sheet is 17 wt%;

[0078] S3. Prepare a PEI film, melt the pure PEI resin at a processing temperature of 300 - 350 °C, extrude and cast and conduct longitudinal stretching with a stretching ratio of 1.6, and the temperature of the rollers passed through during stretching is 200 - 260 °C to obtain a PEI film with a thickness of 0.15 mm;

[0079] Hot pressing and forming: On the cavity sealing plate and PI isolation film of the mold, first coat the high-temperature release agent 2 - 3 times with an interval of 5 - 8 min between each coating to prepare for mold loading;

[0080] Stack the carbon fiber-reinforced thermoplastic composite felt sheet and the PEI film alternately in layers (a total of 43 layers, 21 layers of composite felt sheet and 22 layers of PEI film), place the coated PI isolation film on the upper and lower outer surfaces of the stacked materials, and move them into the mold together;

[0081] Close the mold on the hot pressing equipment, maintain it at a cold pressure of 3 MPa for 20 min, adjust to 1 MPa for pre-pressing, then heat up to 240 °C, keep the temperature for 20 min after reaching the temperature, then heat up to 330 °C, stop heating after reaching the temperature, and then increase the pressure by 1 MPa every 8 min until 6 MPa, and then increase the pressure by 1 MPa every 5 min until 14 MPa. After the displayed temperature naturally cools to 220 °C, quickly cool it down through an external cooling device, with a cooling rate of about 6 °C / min. After the temperature drops below 140 °C, demold to obtain a carbon fiber felt reinforced composite product.

[0082] In the product of this case: the proportion of continuous carbon fiber is 38 wt%, the proportion of carbon fiber pre-oxidized silk staple fiber is 16 wt%, the proportion of PPS is 12 wt%, and the proportion of PEI is 34 wt%.

[0083] Comparative Example 1

[0084] Melt-blend and granulate PEEK resin and chopped carbon fiber (with the same diameter and aspect ratio as the pre-oxidized silk parameters in Example 1) at a processing temperature of 360 °C, and then make it into sheets; after the carbon fiber cloth is desized at a high temperature of 400 °C, perform surface ion etching treatment (etching parameters are the same as those in Preparation Example 1), and perform hot pressing after laminating (hot pressing parameters are the same as those in Example 1), and control the proportions of PEEK, chopped carbon fiber, and continuous carbon fiber to be the same as those in the product of Example 1.

[0085] Perform performance tests on Examples 1-4 and Comparative Example 1, and the test results are shown in Table 1.

[0086] Table 1 Performance of Examples 1-4 and Comparative Example 1

[0087]

[0088] As can be seen from Table 1, the interlaminar shear strength of the laminated product prepared by the conventional method (Comparative Example 1) is relatively low, while the laminated product obtained by the method of the present invention has better tensile strength and interlaminar shear strength.

[0089] As described above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a carbon fiber felt reinforced composite material, characterized in that: The steps include: S1, performing surface ion etching treatment on the thermoplastic fiber filaments and the slurry-free continuous carbon fiber yarn respectively, and weaving the treated thermoplastic fiber filaments and the slurry-free continuous carbon fiber yarn to obtain a mixed plain fabric; The thermoplastic fiber filament is selected from one or more of PAEK fiber, PPS fiber, TPI fiber, PEI fiber, and PPSU fiber; The weaving is performed by using the pulp-free continuous carbon fiber yarn as the weft and thermoplastic fibers and pulp-free continuous carbon fibers arranged evenly at intervals as the warp to perform plain weaving; or thermoplastic fiber filaments and continuous carbon fiber yarns are ply-plied in proportion and then used as single yarns to perform plain weaving; The surface ion etching treatment is carried out by using a vacuum plasma device, the internal plasma nozzle is 5-8 mm away from the material surface, the plasma excitation frequency is 25 KHz, the power during treatment is 500-3000 W, the gas used during treatment is nitrogen or helium, the gas flow rate during treatment is 50-200 L / min, and the treatment time is 1-10 min; S2, using the mixed plain fabric as the base layer and the carbon fiber preoxidized short fibers as the filler, and subjecting the mixture to a needle punching treatment to obtain a carbon fiber reinforced thermoplastic material composite felt sheet; S3, stacking the carbon fiber reinforced thermoplastic composite felt sheet and the thermoplastic film in an alternating manner, and then hot pressing to obtain a carbon fiber felt reinforced composite material; The thermoplastic material film is selected from one or more of PAEK film, PPS film, TPI film, PEI film, and PPSU film fiber; The mold is closed on the hot pressing equipment, and the cold pressure of 3MPa is maintained for 20 minutes, and then adjusted to 1MPa for pre-pressing, and then the temperature is raised to 260-330℃, and the temperature is kept for 20-40 minutes after reaching the temperature, and then the temperature is raised to 320-400℃, and the heating is stopped after reaching the temperature, and then the pressure is increased by 1MPa every 8 minutes to 4-8MPa, and then the pressure is increased by 1MPa every 5 minutes to 12-20MPa, and after the displayed temperature is naturally cooled to 220-260℃, the temperature is quickly cooled by an external cooling device, and the cooling rate is 3-6℃ / min. After the temperature drops below 140℃, the product is demoulded to obtain the product; The carbon fiber felt reinforced composite material comprises, calculated based on 100% weight percentage, 35-50wt% of continuous carbon fiber, 10-18% of carbon fiber preoxidized short fibers, and the remainder being thermoplastic material.

2. The method for preparing a carbon fiber felt reinforced composite material according to claim 1, characterized in that: The PAEK fiber is selected from one or more of PEEK fiber, PEK fiber, PEKK fiber, PEEKK fiber, and PEKEKK fiber; the fiber diameter ranges from 0.2 to 0.8 mm; The size of the slurry-free continuous carbon fiber yarn is 1K to 6K, and the width is at least 1mm; The PAEK film is selected from one or more of PEEK film, PEK film, PEKK film, PEEKK film, and PEKEKK film, and the film thickness ranges from 0.05 to 0.2 mm.

3. The method for preparing a carbon fiber felt reinforced composite material according to claim 1, characterized in that: The ratio of the number of thermoplastic fibers to the number of pulp-free continuous carbon fiber yarns in the warp is 1:1-2, and the ratio of the number of weft fibers to the number of warp fibers is 2-5:1; The continuous carbon fibers account for 50-80 wt % of the mixed plain fabric.

4. The method for preparing a carbon fiber felt reinforced composite material according to claim 1, characterized in that: The surface ion etching treatment is a continuous treatment, which includes unwinding, ion etching, cleaning, drying and winding steps; the unwinding speed is 1-10 m / min; the material after ion etching is uniformly placed in a solution tank for continuous cleaning treatment, using ethanol solution for immersion cleaning.

5. The method for preparing a carbon fiber felt reinforced composite material according to claim 1, characterized in that: The thermoplastic material film is a film stretched after melt extrusion, the processing temperature range of melt extrusion is between 300-420°C, it is longitudinally stretched, the stretching ratio is 1.1-1.8 times, and the processing temperature during stretching is 240-320°C.

6. The method for preparing a carbon fiber felt reinforced composite material according to claim 1, characterized in that: The hot pressing molding: first apply a high-temperature release agent 2-3 times on the cavity sealing plate and PI isolation film of the mold, with an interval of 5-8 minutes between each application, to prepare for mold installation; The carbon fiber reinforced thermoplastic composite felt sheet and the thermoplastic film are stacked alternately in sequence, and the coated PI isolation film is placed on the upper and lower outer surfaces of the stacked materials, and moved into the mold together.

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