Method for forming a carbon fiber prepreg based on ethylene propylene diene terpolymer resin

Abstract

The application relates to the technical field of thermal insulation materials, and particularly discloses a forming method of a ternary ethylene-propylene resin-based carbon fiber prepreg, which comprises the following steps: S1, ternary ethylene-propylene rubber is dissolved with a solvent to prepare glue solution; S2, after the carbon fiber is cut and pre-baked, the carbon fiber is placed into a mold, the glue solution prepared in S1 is added to perform impregnation, and the mold is placed in a vacuum impregnation tank to perform protective atmosphere pressure impregnation; S3, after the impregnation is completed, the material is taken out, the glue solution on the surface is scraped off, and the material is horizontally placed to obtain ternary ethylene-propylene resin-based carbon fiber prepreg after the solvent is volatilized. According to the method, the interface bonding performance of the ternary ethylene-propylene resin-based carbon fiber prepreg and the ternary ethylene-propylene resin is improved by controlling the viscosity and dosage of the impregnation glue solution and adopting the glue solution scraping step.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid rocket engine heat-insulating ablation-resistant materials, and particularly relates to a forming method of ternary ethylene-propylene resin-based carbon fiber prepreg. BACKGROUND

[0002] The heat-insulating material of a solid rocket engine can effectively prevent high-temperature and high-pressure gas and flame generated by propellant from damaging the engine shell, and the performance and quality of the heat-insulating material are important factors affecting the working reliability of the solid rocket engine. Carbon fiber woven body reinforced composite material can significantly improve the ablation resistance and erosion resistance of the heat-insulating material due to its high strength, high impact resistance, and high temperature resistance, and is often used as a reinforcing layer of the heat-insulating layer at the tail of the straight cylinder section and the rear head of the shell.

[0003] At present, the main researches include a double-vacuum bag impregnation forming process and a vacuum pressure tank impregnation forming process. However, the ternary ethylene-propylene resin has a large polarity, the viscosity of the prepared impregnation glue solution is uneven, and the fluctuation is large. The vacuum action accelerates the separation of ternary ethylene-propylene and solvent in the impregnation glue solution, resulting in uneven distribution of the resin matrix. After pressure impregnation, the impregnation glue solution is easily attached to the surface of the carbon fiber woven body in an unimpregnated manner, which seriously affects the forming quality of the prepreg. SUMMARY

[0004] The present application provides a forming method of ternary ethylene-propylene resin-based carbon fiber prepreg, which can improve the forming stability and impregnation amount uniformity of the ternary ethylene-propylene resin-based carbon fiber prepreg.

[0005] The technical scheme of the present application is to provide a forming method of ternary ethylene-propylene resin-based carbon fiber prepreg, which comprises the following steps:

[0006] S1, ternary ethylene-propylene rubber is dissolved with a solvent to prepare a glue solution;

[0007] S2, after the carbon fiber is cut and pre-baked, the carbon fiber is placed in a mold, the glue solution prepared in S1 is added for impregnation, and the mold is placed in a vacuum impregnation tank for protection atmosphere pressure impregnation;

[0008] S3, after the impregnation is completed, the material is taken out, the glue solution on the surface is scraped off, and the material is horizontally placed until the solvent is volatilized to obtain ternary ethylene-propylene resin-based carbon fiber prepreg.

[0009] Optionally, the ternary ethylene-propylene rubber is dissolved with a solvent after being cut; and the viscosity of the glue solution is controlled to be 5-7 Pa·s.

[0010] Optionally, stirring is performed during the dissolving process, the stirring speed is controlled to be 2000-4000 r / min, and the time is controlled to be 20-45 min.

[0011] Optionally, the carbon fiber is T300 12K carbon fiber, which is cut into a square shape.

[0012] Optionally, the temperature of the carbon fiber pre-drying is 50-60℃, and the pre-drying time is 2-3h.

[0013] Optionally, the mold cavity is matched with the shape of the carbon fiber, and the size exceeds the corresponding size of the carbon fiber to be impregnated by 2-4cm; the height of the glue liquid surface is higher than the carbon fiber by 3-5mm during the glue liquid impregnation.

[0014] Optionally, during the vacuum impregnation, nitrogen is used for pressurization, the pressure is controlled at 2.0-2.5MPa, and the pressurization time is controlled at 30-45min.

[0015] Optionally, during the scraping of the surface glue liquid in S3, the impregnated carbon fiber material is horizontally pulled out from between two parallel clamping plates, and the spacing between the two clamping plates is higher than the thickness of the carbon fiber by 1-2mm.

[0016] Optionally, the carbon fiber is pulled out once for each side during the scraping of the surface glue liquid.

[0017] Optionally, the horizontal static time is 72-108h.

[0018] The present application has the following beneficial effects:

[0019] 1. The present application improves the impregnation stability by controlling the glue liquid viscosity and matching the impregnation mold and the addition amount of the glue liquid, and solves the material waste caused by the difficulty in quantifying the impregnation glue liquid.

[0020] 2. After the impregnation is completed, the glue liquid scraping operation is added, which solves the problems of excessive glue liquid on the surface of the EP resin-based carbon fiber prepreg and large difference in the impregnation amount of the same batch.

[0021] 3. The present application also effectively improves the forming stability of the EP resin-based carbon fiber prepreg by controlling the carbon fiber specification and pre-drying conditions, the impregnation tank impregnation pressure and time. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a top view and front view of the impregnation mold used in the present application.

[0023] Figure 2 It is a scraping tool used in the present application.

[0024] Figure 3 It is a photo of the EP resin-based carbon fiber prepreg, wherein A is prepared by the method of Example 1, and B is prepared by the preparation method of Comparative Example 1.

[0025] Figure 4 It is a six-point sampling schematic diagram for characterizing the uniformity of the carbon fiber impregnation. DETAILED DESCRIPTION

[0026] The present application will be described in detail below in conjunction with specific embodiments. The embodiments are implemented on the premise of the technical solutions of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following embodiments.

[0027] The experimental methods in the following embodiments are all conventional methods unless otherwise specified. The raw materials, reagents and materials used in the following embodiments are all commercially available products unless otherwise specified.

[0028] The present application provides a method for forming a carbon fiber prepreg based on a ternary ethylene-propylene resin, comprising the following steps:

[0029] S1, dissolving the ternary ethylene-propylene rubber with a solvent to prepare a glue solution;

[0030] S2, after the carbon fiber is cut and pre-baked, it is placed in a mold, the glue solution prepared in S1 is added for impregnation, and the mold is placed in a vacuum impregnation tank for protective atmosphere pressure impregnation;

[0031] S3, after impregnation, the material is taken out, the glue solution on the surface is scraped off, and the material is placed horizontally until the solvent volatilizes to obtain a ternary ethylene-propylene resin-based carbon fiber prepreg.

[0032] In some embodiments, the ternary ethylene-propylene rubber is dissolved with a solvent after being cut; preferably, it is cut into pieces with an area not higher than 1 cm 2 , so that it can be quickly dissolved. The viscosity of the glue solution is controlled at 5-7 Pa·s. In addition to the ternary ethylene-propylene rubber, the glue solution can also add an appropriate amount of phenolic resin and vulcanizing agent and other additives as needed.

[0033] In some embodiments, the carbon fiber is T300 12K carbon fiber, which is cut into a square shape. In the following embodiments, it is cut into a square shape of 19 cm*19 cm and placed in an oven for pre-baking at 50-60℃ for 2-3h.

[0034] In some embodiments, the mold cavity matches the shape of the carbon fiber, and the size exceeds the corresponding size of the carbon fiber to be impregnated by 2-4 cm; the height of the glue solution liquid surface during glue solution impregnation is higher than that of the carbon fiber by 3-5 mm. In the following embodiments, the mold is made of stainless steel, and its structure is as shown in Figure 1 , which is provided with a groove matching the shape of the carbon fiber, and the size of the groove is 22 cm*22 cm. During impregnation, the mold is placed in a tray and hung in a vacuum pressure impregnation tank, and the top cover is closed.

[0035] In some embodiments, during vacuum impregnation, nitrogen is used for pressurization, the pressure is controlled at 2.0-2.5 MPa, and the pressurization time is controlled at 30-45 min.

[0036] In some embodiments, the glue solution on the scraped surface in S3 is pulled horizontally out from between two parallel clamps, with a spacing of 1-2 mm higher than the thickness of the carbon fiber. The present application also provides a scraping tooling, which includes two parallel stainless steel plates arranged above and below, with a spacing adjusted by bolts, as shown in Figure 2 The two surfaces of the carbon fiber are each pulled out once.

[0037] In some embodiments, after the glue solution on the scraped surface, the material is ventilated and horizontally placed for 72-108 h.

[0038] The present application will be described in detail below with specific examples. The present embodiment is implemented on the premise of the technical solution of the present application, and gives detailed implementation modes and specific operation processes, but the protection scope of the present application is not limited to the following examples.

[0039] Example 1:

[0040] (1) Preparation of impregnation glue solution: cut the EPDM resin into pieces with an area less than 1 cm 2 , add solvent, and stir uniformly with a high-speed stirrer. The stirring speed is controlled at 2500 r / min, and the stirring time is controlled at 40 min. The uniformly mixed EPDM resin-based glue solution is sampled and tested for a glue viscosity of 6.5 Pa·s.

[0041] (2) Pretreatment of carbon fiber: select carbon fiber with a specification of T300 12K, cut into a square of 19 cm*19 cm, and put into an oven for pre-drying at 55°C for 2 h.

[0042] (3) Carbon fiber soaking: put the carbon fiber into a 22 cm*22 cm stainless steel mold, add an appropriate amount of impregnation glue solution to make the glue solution about 4 mm higher than the carbon fiber. Put the mold into a tray and hang it in a vacuum pressure impregnation tank, and close the top cover.

[0043] (4) Pressure impregnation: after removing the air in the tank, inject nitrogen. The pressure in the tank is controlled at 2.5 MPa for 30 min.

[0044] (5) Glue scraping: take out the prepreg, lay it into the scraping tooling, and pull it out horizontally from the other end of the tooling. Repeat the above operation after turning over the prepreg.

[0045] (6) Ventilation and drying: place the prepreg in a fume hood and horizontally place it for 72 h.

[0046] The related properties of the prepreg prepared in this test are shown in Table 1, and the actual photos are shown in Figure 3 A. Among them, when sampling the uniformity of the impregnated glue, the prepreg is ventilated to volatilize the solvent, and the prepreg is cut into a 1 cm 2 square for testing.Figure 4 The six points of the prepreg were cut to a diameter of 2 cm, weighed, and used to represent the uniformity of the carbon fiber impregnation. The reference standard for the interface performance was QJ 2038.1A-2004 “Solid Rocket Motor Combustion Chamber Interface Bonding Strength Test Method”.

[0047] Table 1

[0048]

[0049] Example 2:

[0050] (1) Preparation of impregnation glue solution: The EPDM rubber was cut into small pieces with an area of less than 1 cm 2 , and solvent was added, and stirred uniformly with a high-speed stirrer. The stirring speed was controlled at 3000 r / min, and the time was controlled at 35 min. The uniformly mixed EPDM resin-based glue solution was sampled and tested, and the glue solution viscosity was 7.0 Pa·s.

[0051] (2) Pretreatment of carbon fiber: The carbon fiber with a specification of T300 12K was cut into a square of 19 cm*19 cm, and placed in an oven for 2 h at 60°C.

[0052] (3) Carbon fiber soaking: The carbon fiber was placed in a 22 cm*22 cm stainless steel mold, and an appropriate amount of impregnation glue solution was added to the glue solution to be about 3 mm higher than the carbon fiber. The mold was placed in a tray and hung in a vacuum pressure impregnation tank, and the top cover was closed.

[0053] (4) Pressure impregnation: After removing the air in the tank, nitrogen was injected. The pressure in the tank was controlled at 2.4 MPa for 35 min.

[0054] (5) Glue solution scraping: The prepreg was taken out, laid and inserted into the scraping tool, and pulled out horizontally from the other end of the tool. After turning over the prepreg, the above action was repeated again.

[0055] (6) Ventilation and drying: The prepreg was placed in a fume hood and horizontally placed for 84 h.

[0056] The related properties of the prepreg prepared in this test are shown in Table 2.

[0057] Table 2

[0058]

[0059] Example 3:

[0060] (1) Preparation of impregnation glue solution: The EPDM rubber was cut into small pieces with an area of less than 1 cm 2The chunks were added into the solvent and stirred with a high-speed stirrer. The stirring speed was controlled at 4000 r / min and the stirring time was controlled at 20 min. The viscosity of the mixed EPDM-based sizing solution was 5.1 Pa·s.

[0061] (2) Pretreatment of carbon fibers: Carbon fibers with a specification of T300 12K were selected, cut into squares of 19 cm*19 cm, and placed in an oven for pre-drying at 50°C for 3 h.

[0062] (3) Carbon fiber soaking: The carbon fibers were placed in a 22 cm*22 cm stainless steel mold, and an appropriate amount of sizing solution was added until the sizing solution was about 5 mm higher than the carbon fibers. The mold was placed in a tray and hung in a vacuum pressure impregnation tank, and the top cover was closed.

[0063] (4) Pressure impregnation: After removing the air in the tank, nitrogen was injected. The pressure in the tank was controlled at 2.0 MPa for 45 min.

[0064] (5) Sizing solution scraping: The prepreg was taken out, laid into the scraping tool, and pulled out horizontally from the other end of the tool. The prepreg was turned over and the above operation was repeated again.

[0065] (6) Ventilation and drying: The prepreg was placed in a fume hood and horizontally placed for 108 h.

[0066] Table 3

[0067]

[0068] Comparative Example 1

[0069] (1) Preparation of sizing solution: The EPDM rubber was placed in a solvent and stirred. The stirring speed was controlled at 6000 r / min and the stirring time was controlled at 30 min.

[0070] (2) Pretreatment of carbon fibers: Carbon fibers with a specification of T300 12K were selected, cut into squares of 19 cm*19 cm, and placed in an oven for pre-drying at 50°C for 1 h.

[0071] (3) Carbon fiber soaking: The carbon fibers were placed in a container that could evenly spread, such as a stainless steel basin, and the sizing solution was added until the carbon fibers were completely immersed.

[0072] (4) Pressure impregnation: After removing the air in the tank, nitrogen was injected. The pressure in the tank was controlled at 2.0 MPa for 60 min.

[0073] (5) Ventilation and drying: The prepreg was placed in a fume hood and horizontally placed for 96 h.

[0074] The photos of the prepared prepreg are shown in Figure 3 B.

[0075] From Figure 3 It can be seen that the carbon fiber prepreg prepared by the conventional method in Comparative Example 1 has uneven resin distribution, the impregnation amount of the edge region is obviously lower than that of the middle region, and a large amount of unimpregnated resin exists on the surface of the carbon fiber in an attached manner. The carbon fiber prepreg prepared by the method of the present application has uniform impregnation amount in each region, and the impregnated resin attached on the surface has been completely scraped off.

[0076] Comparative Example 2

[0077] Based on Example 1, the only difference is that the amount of EPDM used is reduced and the amount of solvent is increased to control the viscosity of the sizing solution to 3.5 Pa•s.

[0078] The appearance of the prepared prepreg is shown in Figure 3 C, and the performance is shown in Table 4. There is no excess sizing solution on the surface, but it is difficult to impregnate and attach due to the too low viscosity of the sizing solution, the impregnation amount is much lower than the required value, and the interfacial performance is poor.

[0079] Table 4

[0080]

[0081] Comparative Example 3

[0082] Based on Example 1, the only difference is that the amount of EPDM used is increased and the amount of solvent is reduced to control the viscosity of the sizing solution to 7.8 Pa•s.

[0083] The appearance of the prepared prepreg is shown in Figure 3 D, and the performance is shown in Table 5. The sizing solution has a large viscosity, it is difficult to scrape off uniformly, resulting in sizing solution attached on the surface, the impregnation amount is high, and there is a problem of poor batch stability.

[0084] Table 5

[0085]

[0086] Comparative Example 4

[0087] The same as Example 1, the only difference is that the sizing solution is scraped off by a manual scraper in step (5).

[0088] The appearance of the prepared prepreg is shown in Figure 3 E, and the performance is shown in Table 6. The scraping effect of the manual scraper depends on the operator, there is instability and difference, resulting in poor uniformity of the sizing solution impregnation amount.

[0089] Table 6

[0090]

[0091] Comparative Example 5

[0092] The difference between the example 1 and the example 2 is that the liquid level of the glue solution is 1 cm higher than the carbon fiber during the carbon fiber soaking in step (3).

[0093] The appearance of the prepared prepreg is shown in Fig. F, and the performance is shown in Table 7. The impregnation amount is relatively uniform, and there is no obvious excess glue solution on the surface, but the impregnation amount is relatively high. Figure 3

[0094] Table 7

[0095]

[0096] The above examples describe the preferred embodiments of the present application, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other manner, and these simple modifications and combinations should also be considered as the disclosed content of the present application, and all belong to the protection scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.​

Claims

1. A method for forming an EPDM resin-based carbon fiber prepreg, characterized in that: The following steps are involved: S1, dissolving EPDM rubber with a solvent to prepare a glue solution; S2: After cutting, pre-dry the carbon fiber, place it in a mold, add the glue prepared in S1 for impregnation, and place the mold in a vacuum impregnation tank for pressure impregnation under protective atmosphere; S3. After the impregnation is completed, the material is taken out, the glue on the surface is scraped off, and the material is left to stand in a ventilated horizontal position until the solvent evaporates to obtain an EPDM resin-based carbon fiber prepreg.

2. The molding method according to claim 1, wherein: After cutting, the EPDM rubber is dissolved in a solvent; the viscosity of the rubber solution is controlled at 5-7 Pa•s.

3. The molding method according to claim 1, wherein: Stirring is performed during the dissolution process, with a stirring speed of 2000-4000 r / min and a time controllable within 20-45 min.

4. The molding method according to claim 1, wherein: The carbon fiber is T300 12K carbon fiber, which is cut into squares.

5. The molding method according to claim 1, wherein: The carbon fiber pre-baking temperature is 50-60°C and the pre-baking time is 2-3 hours.

6. The molding method according to claim 1, wherein: The mold cavity matches the shape of the carbon fiber, and its size exceeds the corresponding size of the carbon fiber to be impregnated by 2-4 cm; when the glue is impregnated, the height of the glue liquid level is 3-5 mm higher than the carbon fiber.

7. The molding method according to claim 1, wherein: During vacuum impregnation, nitrogen is used for pressurization, the pressure is controlled at 2.0-2.5 MPa, and the pressurization time is controlled at 30-45 minutes.

8. The molding method according to any one of claims 1 to 7, characterized in that: When scraping off the glue on the surface in S3, the impregnated carbon fiber material is pulled horizontally out from between two parallel plywood plates, and the distance between the two plywood plates is 1 to 2 mm higher than the thickness of the carbon fiber.

9. The molding method according to claim 8, characterized in that: When scraping off the glue on the surface, pull both sides of the carbon fiber upwards and do the operation once.

10. The molding method according to any one of claims 1 to 7, characterized in that: The horizontal standing time is 72-108h.

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