Low-temperature-resistant high-modulus carbon fiber prepreg and preparation method thereof

Abstract

The invention discloses a low-temperature-resistant high-modulus carbon fiber prepreg and a preparation method thereof, and relates to the field of composites.The preparation method comprises the steps that a temperature rise rheology curve of low-temperature-resistant resin is obtained, and the preheating temperature, the first rolling temperature, the second rolling temperature and the low-temperature-resistant resin adhesive film and high-modulus carbon fiber compounding temperature are obtained according to the temperature rise rheology curve; sequentially carrying out preheating, first rolling and second rolling on the low-temperature-resistant resin to obtain a low-temperature-resistant resin adhesive film; wherein the temperatures of preheating and multiple rolling in sequence are in a rising trend; and compounding the low-temperature-resistant resin adhesive film and the high-modulus carbon fiber. And the thickness uniformity control of the low-temperature-resistant resin film and the uniform impregnation of the high-modulus carbon fiber are realized. The method has the characteristics of high operability and stable product performance.

Description

Technical Field

[0001] The present invention belongs to the field of composite materials, and relates to a cryogenic-resistant high-modulus carbon fiber prepreg and a preparation method thereof. This forming method is mainly applied to the manufacture of cryogenic-resistant composite structural parts and has good application value in fields such as deep space exploration. Background Art

[0002] The development of payload lightweight in the field of deep space exploration urgently demands high-modulus carbon fiber resin-based composite structures for service in low-temperature environments. At low temperatures, the toughness of the resin matrix is poor, and the thermal stress concentration caused by the mismatch between its thermal expansion coefficient and that of high-modulus carbon fibers is an important factor for the failure of composite materials at low temperatures. The current cryogenic-resistant resin systems are mainly high-toughness epoxy resin systems. By multi-scale synergistic toughening modification, while improving the toughness of the resin matrix, the thermal expansion coefficient is reduced, which can effectively improve the cryogenic resistance of composite materials.

[0003] The application of cryogenic-resistant resins requires compounding with high-modulus carbon fibers to prepare prepregs. Usually, the two-step hot melting method is adopted. This method has high requirements for the resin film. The precise control of the resin film thickness and uniformity is very important for ensuring the performance of the prepreg such as the resin content and wetting uniformity. The unique toughening modification groups in the cryogenic-resistant resin system affect the molecular chain segment configuration and position in the resin system, causing changes in the steric hindrance effect and free volume of macromolecules, resulting in changes in the energy required for molecular chain and molecular network movement, thereby causing the film-forming ability of the resin matrix to vary according to the different chemical compositions of the system, significantly affecting the control of the rheological properties and film-forming properties of the resin, and further affecting the preparation quality of the resin film and its wettability to high-modulus carbon fibers. During the preparation of the resin film, in order to make the cryogenic-resistant resin form a uniform film, it is necessary to raise the temperature to reduce the resin viscosity, but at the same time, it will also cause a certain degree of pre-curing of the resin. The change in the resin viscosity leads to non-uniform film thickness, affecting the wetting of the resin to the fibers during the subsequent composite curing process and having an adverse impact on the performance of the composite material product.

[0004] Therefore, the preparation of cryogenic-resistant high-modulus carbon fiber prepregs is difficult and has high process technical requirements, and the domestic technology is not yet mature. Summary of the Invention

[0005] The technical problem solved by this application is: overcoming the deficiencies of the prior art, providing a cryogenic-resistant resin-based high-modulus carbon fiber prepreg and a preparation method thereof, and the prepared prepreg has a low degree of pre-curing and good film-forming properties.

[0006] This application also realizes the control of the thickness uniformity of the cryogenic-resistant resin film and the uniform impregnation of high-modulus carbon fibers. It has the characteristics of strong operability and stable product performance.

[0007] The technical solution provided by this application is as follows:

[0008] In a first aspect, a method for preparing a low-temperature resistant and high-modulus carbon fiber prepreg is provided, including:

[0009] Obtain the heating rheological curve of the low-temperature resistant resin, and obtain the temperatures for preheating, the first rolling, the second rolling, and the lamination of the low-temperature resistant resin film and the high-modulus carbon fiber according to the heating rheological curve;

[0010] Preheat, perform the first rolling, and then perform the second rolling on the low-temperature resistant resin in sequence to obtain a low-temperature resistant resin film; wherein the temperatures for the sequential preheating and multiple rollings show an upward trend;

[0011] Lay up the low-temperature resistant resin film and the high-modulus carbon fiber.

[0012] Further, the step of obtaining the temperatures for preheating, the first rolling, the second rolling, and the lamination of the low-temperature resistant resin film and the high-modulus carbon fiber according to the heating rheological curve includes:

[0013] The preheating and the first rolling correspond to the low-temperature resistant resin within a first viscosity range, the second rolling corresponds to the low-temperature resistant resin within a second viscosity range, and the lamination corresponds to the low-temperature resistant resin within a third viscosity range; obtain the temperature range corresponding to the first viscosity range as the temperature range for preheating and the first rolling according to the heating rheological curve; obtain the temperature range corresponding to the second viscosity range as the temperature range for the second rolling according to the heating rheological curve; obtain the temperature range corresponding to the third viscosity range as the temperature range for lamination according to the heating rheological curve.

[0014] Further, the first viscosity range > the second viscosity range > the third viscosity range.

[0015] Further, the first viscosity range is 50 - 150 Pa·s; the second viscosity range is 20 - 30 Pa·s; the third viscosity range is 5 - 10 Pa·s.

[0016] Further, the low-temperature resistant resin is an epoxy resin modified by multi-scale synergistic toughening. The multi-scale synergistic toughening is to modify the epoxy resin with a modifier, and the modifier is any one or more of nano-inorganic modification particles and micro-scale modification particles. The micro-scale modification particles are core-shell structure elastomers, thermoplastic microspheres, and / or elastomer particles.

[0017] The nano-inorganic modification particles are silica, carbon nanotubes, and / or graphene nanoparticles; the core-shell structure elastomer (such as polybutene), the thermoplastic microsphere (such as PEEK), and the elastomer particle (such as silicone rubber).

[0018] Further, the preheating temperature of the low-temperature resistant resin is 62°C to 72°C; the temperature of the first glue coating roller in the first rolling is 62°C to 72°C, and the temperature of the second glue coating roller in the second rolling is 75°C to 85°C.

[0019] Further, when the low-temperature resistant resin film and the high-modulus carbon fiber are compounded, the high-modulus carbon fiber is first unwound; the unwinding parameters of the high-modulus carbon fiber are: the temperature is 80°C to 90°C, the frequency of the unwinding roller is (6 - 10) Hz, and the amplitude is (4 - 6) mm.

[0020] Further, when the low-temperature resistant resin film and the high-modulus carbon fiber are compounded, the unwound high-modulus carbon fiber is laminated with the low-temperature resistant resin film to obtain a composite layer, and the composite layer is successively passed through multiple hot pressing rollers; the temperature of the hot pressing rollers is 90°C to 110°C.

[0021] Further, the temperature of the multiple hot pressing rollers increases step by step and the gap decreases step by step.

[0022] In a second aspect, a low-temperature resistant high-modulus carbon fiber prepreg is provided, which is obtained by the preparation method of the low-temperature resistant high-modulus carbon fiber prepreg according to any one of the above.

[0023] In summary, the present application at least includes the following beneficial technical effects:

[0024] The present invention provides a low-temperature resistant high-modulus carbon fiber prepreg and a preparation method thereof. By controlling the process parameters of film preparation and fiber / resin compounding, the thickness uniformity of the low-temperature resistant resin film is controlled and the high-modulus carbon fiber is uniformly impregnated. It has the characteristics of strong operability and stable product performance, filling the domestic gap in the low-temperature resistant high-modulus carbon fiber prepreg and its preparation method.

[0025] This method can be applied to the preparation of low-temperature resistant resin / high-modulus carbon fiber prepreg by a two-step hot melting method. The composite material made from it has good low-temperature mechanical properties, great lightweight potential, and a large degree of freedom in integrated structure and function design, and can provide strong technical support for the extreme environment service and high-reliability design of spacecraft composite structures. The product can also be extended to components such as aeroengines and ships, which can significantly improve the service life, service safety, and stability of key components, and has great practical value and economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the glue coating mechanism;

[0027] Figure 2 It is the heating and rheological curve of the 601 low-temperature resistant resin;

[0028] Figure 3 It is the DSC curve of the 601 low-temperature resistant resin and the low-temperature resistant resin film;

[0029] Figure 4 is the weight change curve of the 601 low-temperature resistant resin film;

[0030] Figure 5 is the appearance of the 601 low-temperature resistant resin / CCM40J-6K carbon fiber prepreg.

[0031] Figure 6 is the heating rheological curve of the BS8 low-temperature resistant resin;

[0032] Figure 7 is the DSC curve of the BS8 low-temperature resistant resin and the low-temperature resistant resin film;

[0033] Figure 8 is the weight change curve of the BS8 low-temperature resistant resin film;

[0034] Figure 9 is the appearance of the BS8 low-temperature resistant resin / CCM40J-6K carbon fiber prepreg. Specific Embodiments

[0035] To make the objectives, technical solutions and advantages of the present invention clearer, the following will further describe in detail the disclosed embodiments of the present invention in conjunction with the accompanying drawings.

[0036] The low-temperature resistant resin targeted by this application, such as an epoxy resin modified by multi-scale synergistic toughening.

[0037] The low-temperature resistant resin has a high viscosity. When preparing the low-temperature resistant resin into a film, it is necessary to heat up the low-temperature resistant resin to reduce its viscosity. However, long-term high-temperature heating will cause the low-temperature resistant resin to undergo a curing reaction and the viscosity of the low-temperature resistant resin will increase (i.e., the pre-curing degree of the low-temperature resistant resin is relatively large), which will affect the uniformity of the resin film and is not conducive to the resin fully impregnating the fibers and the properties of the composite material.

[0038] The embodiments of this application disclose a low-temperature resistant high-modulus carbon fiber prepreg and its preparation method, including the preparation of a low-temperature resistant resin film and the compounding of the low-temperature resistant resin / high-modulus carbon fiber in sequence.

[0039] The specific implementation steps are as follows:

[0040] Preparation of the low-temperature resistant resin film: Determine the film preparation temperature and the compounding temperature range according to the heating rheological curve of the low-temperature resistant resin; Set the gap parameters of two coating rollers according to the required film thickness, and gradually compress the resin to prepare a resin film with a required weight.

[0041] Compound the low-temperature resistant resin film / high-modulus carbon fiber: Set the yarn spreading parameters and the gap of the hot pressing roller, and make the high-modulus carbon fiber pass through the yarn spreading device to be evenly thinned and then compound with the resin film to obtain the low-temperature resistant resin / high-modulus carbon fiber prepreg.

[0042] The specific steps for preparing the low-temperature resistant resin film are as follows:

[0043] (1) Set the preheating temperature of the resin in the glue tank to 62°C - 72°C, the temperature of the first coating roller to 62°C - 72°C, and the gap between the coating rollers to 0.12 mm - 0.20 mm, so that the resin is pre-pressed to obtain a resin film with a grammage of (30 - 50) g / m 2 ².

[0044] (2) Set the temperature of the second coating roller to 75°C - 85°C, and the gap between the coating rollers to 0.03 mm - 0.08 mm, so that the grammage of the resin is reduced to (10 - 25) g / m 2 ².

[0045] (3) Carry out resin coating for 3 m - 10 m, stop the machine and measure the grammage of the film actually. If the measured value of the film grammage meets the requirements, start preparing the film; if not, adjust the gap between the coating rollers until the film grammage meets the requirements.

[0046] The specific steps for the composite of the low-temperature resistant resin film / high modulus carbon fiber are as follows:

[0047] (1) Set the temperature of the yarn spreading parameters to 80°C - 90°C, the frequency of the yarn spreading roller to (6 - 10) Hz, and the amplitude to (4 - 6) mm, and uniformly spread the high modulus carbon fiber.

[0048] (2) Set the temperature of the hot pressing roller of the composite system to 90°C - 100°C to make the low-temperature resistant resin have a certain fluidity;

[0049] (3) Set the gap between the hot pressing rollers of the composite system to 0.24 mm - 0.30 mm to make the low-temperature resistant resin fully impregnate the fibers under the action of pressure.

[0050] The low-temperature resistant resin refers to an epoxy resin modified by multi-scale synergistic toughening, which not only increases the toughness of the resin matrix but also reduces the coefficient of thermal expansion, making the resin have a good match with the high modulus carbon fiber. The tensile strength of the resin at room temperature ≥ 70 MPa; the elongation at break ≥ 6%; the elongation at break at 77 K ≥ 1.5%; the coefficient of thermal expansion ≤ 30×10 -6 ⁻⁶ / K.

[0051] The high modulus carbon fiber mentioned above refers to carbon fiber with higher modulus after high-temperature graphitization (M series, MJ series), which has the advantages of high specific strength, high specific stiffness, low coefficient of thermal expansion and good space environment stability, and is widely used in spacecraft structures. Common high modulus carbon fibers are shown in Table 1.

[0052] Table 1 Main parameters of high modulus carbon fiber

[0053] High modulus carbon fiber Tensile strength (MPa) Tensile modulus (GPa) M40 grade ≥2720 ≥390 M40J grade ≥4400 ≥370 M55J grade ≥4020 ≥540 M65J grade ≥3850 ≥630

[0054] The first glue - applying roller pre - presses the resin onto a resin film with a grammage of (30 - 50) g / m 2 , and the form can be but is not limited to Figure 1 the form of a round roller shown. The gap of the first roller is the gap between roller A and roller B, and the temperature is the temperature of roller A and the glue tank.

[0055] The second glue - applying roller further thins the resin to a resin film with a grammage of (10 - 25) g / m 2 , and the form can be but is not limited to Figure 1 the form of a round roller shown. The gap of the second roller is the gap between roller B and roller C, and the temperature is the temperature of roller B and roller C.

[0056] The temperature of the hot - pressing roller in the composite process is 90°C - 100°C, the gap of the hot - pressing roller is 0.24 mm - 0.30 mm, and 3 - 4 groups of hot - pressing rollers are used. The temperature increases step by step and the gap decreases step by step, so that the low - temperature - resistant resin can flow and impregnate the carbon fiber better, ensuring that the low - temperature - resistant resin uniformly and completely immerses into the carbon fiber and the resin does not cure.

[0057] In the preparation process of the low - temperature - resistant resin film of this application, multi - stage and step - by - step heating is adopted, so that the curing degree of the low - temperature - resistant resin in the film - preparation process is greatly reduced. And due to the reduction of the curing degree and the maintenance of a small viscosity in the film - preparation process, the uniformity of the prepared low - temperature - resistant resin film is improved.

[0058] Example 1

[0059] In this example, a low - temperature - resistant resin / high - modulus carbon fiber prepreg with a thickness of 0.06 mm (fiber areal density (64 ± 3) g / m 2 ) is prepared. The fiber used is high - modulus carbon fiber CCM40J - 6K produced by Weihai Tuozhan Co., Ltd., with a tensile strength of 4590 MPa and a tensile modulus of 372 GPa. The low - temperature - resistant epoxy resin used is 601 resin produced by Dalian University of Technology, with a room - temperature tensile strength of 85 MPa, an elongation at break of 8%; the elongation at break at 77K is 1.8%, and the coefficient of thermal expansion is 24×10 -6 / K. The heating - up rheological curve of the low - temperature - resistant epoxy resin is as Figure 2 shown.

[0060] According to Figure 2 the heating - up rheological curve of the 601 low - temperature - resistant epoxy resin and the set viscosity range, the temperature range for the first roller pressing is 67 - 75°C, the temperature range for the second roller pressing is 78 - 80°C, and the temperature range for the composite is 86 - 95°C.

[0061] The parameters of this embodiment are as follows: the temperature of the film pre-pressing (i.e., the first roller pressing) is 70°C, the pre-pressing gap is 0.16 mm, the temperature of the film preparation (i.e., the second roller pressing) is 79°C, and the gap is 0.05 mm; the temperature of the yarn spreading roller is set at 80°C, the frequency of the vibrating yarn spreading roller is 8 Hz, and the amplitude is 8 mm; the temperatures of the hot pressing rollers are set at 90°C, 93°C, and 95°C respectively, and the gaps of the hot pressing rollers are set at 0.30 mm, 0.27 mm, and 0.25 mm respectively.

[0062] The DSC test curves of the 601 low-temperature resistant resin and the low-temperature resistant resin film are as Figure 3 shown. The degree of curing of the low-temperature resistant resin film prepared by this method is very small, about 1.4%, and the resin has basically not reacted.

[0063] During the preparation of the 250 m long film, the gram weight of the film is tested every 50 m. The test results are as Figure 4 shown. It can be seen that the gram weight of the film changes, but it is within ±0.5 g / m 2 range, and the uniformity is good.

[0064] As Figure 5 is the apparent physical diagram of the prepreg.

[0065] Example 2

[0066] The difference from Example 1 is that the low-temperature resistant resin used is the BS8 resin produced by Beijing Satellite Manufacturing Factory Co., Ltd., with a room temperature tensile strength of 82 MPa and an elongation at break of 7%; the elongation at break at 77K is 1.5%, and the coefficient of thermal expansion is 28×10 -6 / K. The heating rheological curve of the BS8 low-temperature resistant epoxy resin is as Figure 6 shown.

[0067] According to Figure 6 the heating rheological curve of the BS8 low-temperature resistant epoxy resin and the set viscosity range, the temperature range of the first roller pressing is 65 - 75°C, the temperature range of the second roller pressing is 82 - 88°C, and the temperature range of the lamination is 99 - 120°C.

[0068] The parameters of this embodiment are as follows: the temperature of the film pre-pressing (i.e., the first roller pressing) is 70°C, the pre-pressing gap is 0.16 mm, the temperature of the film preparation (i.e., the second roller pressing) is 85°C, and the gap is 0.05 mm; the temperature of the yarn spreading roller is set at 80°C, the frequency of the vibrating yarn spreading roller is 8 Hz, and the amplitude is 8 mm; the temperatures of the hot pressing rollers are set at 100°C, 105°C, and 110°C respectively, and the gaps of the hot pressing rollers are set at 0.30 mm, 0.27 mm, and 0.25 mm respectively.

[0069] The DSC test curves of the BS8 low-temperature resistant resin and the low-temperature resistant resin film are as Figure 7As shown, the curing degree of the low-temperature resistant resin film prepared by this method is very small, about 1.2%, and the resin basically does not react.

[0070] During the preparation of the 250 m long adhesive film, the gram weight of the adhesive film was measured every 50 m. The test results are as Figure 8 shown. It can be seen that the gram weight of the adhesive film changes, but it is within ±0.5 g / m 2 range, and the uniformity is good.

[0071] As shown in Figure 9 is the apparent physical diagram of the prepreg.

[0072] Comparative Example 1

[0073] The difference from Example 1 is only that: the temperatures of the first rolling and the second rolling are both 79 °C.

[0074] The curing degree of the low-temperature resistant resin film prepared by this method is 3.6%.

[0075] During the preparation of the 250 m long adhesive film, the gram weight of the adhesive film was measured every 50 m. The gram weight of the adhesive film changes, and the change in gram weight reaches ±2.1 g / m 2 , and the uniformity decreases.

[0076] Comparative Example 2

[0077] The difference from Example 1 is only that: the temperature of the first rolling is 70 °C, and the temperature of the second rolling is 86 °C.

[0078] The curing degree of the low-temperature resistant resin film prepared by this method is 3.3%.

[0079] During the preparation of the 250 m long adhesive film, the gram weight of the adhesive film was measured every 50 m. The gram weight of the adhesive film changes, and the change in gram weight reaches ±2.0 g / m 2 , and the uniformity decreases.

[0080] The content not described in detail in the specification of this application belongs to the well-known technology of those skilled in the art.

[0081] The above has described this application in detail in combination with specific embodiments and exemplary examples, but these descriptions should not be construed as limiting this application. Those skilled in the art understand that without departing from the spirit and scope of this application, various equivalent replacements, modifications or improvements can be made to the technical solutions and their implementation manners of this application, and these all fall within the scope of this application. The protection scope of this application is subject to the appended claims.

Claims

1. A preparation method of a low-temperature resistant and high-modulus carbon fiber prepreg, characterized in that Including: Obtain the temperature-rising rheological curve of the low-temperature resistant resin, and obtain the preheating temperature, the temperature of the first rolling, the temperature of the second rolling, and the temperature of the composite of the low-temperature resistant resin film and the high-modulus carbon fiber according to the temperature-rising rheological curve; Preheat the low-temperature resistant resin successively, perform the first rolling and the second rolling to obtain a low-temperature resistant resin film; wherein the temperatures of the successive preheating and multi-pass rolling show an upward trend; Composite the low-temperature resistant resin film and the high-modulus carbon fiber.

2. The preparation method of a low-temperature resistant and high-modulus carbon fiber prepreg according to claim 1, wherein: The obtaining of the preheating temperature, the temperature of the first rolling, the temperature of the second rolling, and the temperature of the composite of the low-temperature resistant resin film and the high-modulus carbon fiber according to the temperature-rising rheological curve includes: Preheating and the first rolling correspond to the low-temperature resistant resin in the first viscosity range, the second rolling corresponds to the low-temperature resistant resin in the second viscosity range, and the composite corresponds to the low-temperature resistant resin in the third viscosity range; obtain the temperature range corresponding to the first viscosity range according to the temperature-rising rheological curve as the temperature range of preheating and the first rolling; obtain the temperature range corresponding to the second viscosity range according to the temperature-rising rheological curve as the temperature range of the second rolling; obtain the temperature range corresponding to the third viscosity range according to the temperature-rising rheological curve as the temperature range of the composite.

3. The preparation method of a low-temperature resistant and high-modulus carbon fiber prepreg according to claim 2, wherein: The first viscosity range > the second viscosity range > the third viscosity range.

4. The preparation method of a low-temperature resistant and high-modulus carbon fiber prepreg according to claim 2, wherein: The first viscosity range is 50 - 150 Pa·s; the second viscosity range is 20 - 30 Pa·s; the third viscosity range is 5 - 10 Pa·s.

5. The preparation method of a low-temperature resistant and high-modulus carbon fiber prepreg according to claim 1, characterized in that: The low-temperature resistant resin is an epoxy resin modified by multi-scale synergistic toughening. The multi-scale synergistic toughening modification is to modify the epoxy resin with a modifier, and the modifier is any one or more of nano-inorganic modification particles and micro-scale modification particles. The micro-scale modification particles are core-shell structure elastomers, thermoplastic microspheres, and / or elastomer particles.

6. The preparation method of a low-temperature resistant and high-modulus carbon fiber prepreg according to claim 5, characterized in that, The preheating temperature of the low-temperature resistant resin is 62°C to 72°C; the temperature of the first coating roller for the first rolling is 62°C to 72°C, and the temperature of the second coating roller for the second rolling is 75°C to 85°C.

7. The preparation method of a low-temperature resistant and high-modulus carbon fiber prepreg according to claim 1, characterized in that: When the low-temperature resistant resin film and the high-modulus carbon fiber are composite, first unfold the high-modulus carbon fiber; the spreading parameters of the high-modulus carbon fiber are: the temperature is 80°C to 90°C, the frequency of the spreading roller is (6 - 10) Hz, and the amplitude is (4 - 6) mm.

8. The preparation method of a low-temperature resistant and high-modulus carbon fiber prepreg according to claim 1, characterized in that: When the low-temperature resistant resin film and the high-modulus carbon fiber are composite, superpose the unfolded high-modulus carbon fiber and the low-temperature resistant resin film to obtain a composite layer, and pass the composite layer through multiple hot pressing rollers successively; the temperature of the hot pressing rollers is 90°C to 110°C.

9. The preparation method of a low-temperature resistant and high-modulus carbon fiber prepreg according to claim 8, characterized in that: The temperatures of the multiple hot pressing rollers increase step by step and the gaps decrease step by step.

10. A low-temperature resistant and high-modulus carbon fiber prepreg, characterized in that, Prepared by the preparation method of a low-temperature resistant and high-modulus carbon fiber prepreg according to any one of claims 1 - 9.

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