Chopped fiber reinforced resin-based composite material and preparation method thereof

Abstract

The invention belongs to the field of composite material manufacturing, and particularly relates to a chopped fiber reinforced resin-based composite material and a preparation method thereof.The resin-based composite material is prepared from, by mass, 10-20 parts of chopped fibers, 80-90 parts of a resin matrix and 0.2-1 part of a modifier; the preparation method comprises the following steps: S1, drying polyimide resin of the resin matrix; s2, the chopped fibers are subjected to ultrasonic cleaning with heated deionized water, the cleaned chopped fibers are dried in a low-temperature drying oven, the dried chopped fibers are subjected to ultrasonic soaking in a modifier, then the dried chopped fibers are dried through a high-temperature drying oven, and modified chopped fibers are obtained; s3, feeding the polyimide resin in the S1 and the modified chopped fibers in the S2 according to a proportion, and uniformly mixing through stirring equipment to obtain a mold pressing material; and S4, carrying out hot compression molding on the molded material in the S3 through a hot molding press. The resin-based composite material has the characteristics of light weight, high strength and electrical insulation, and the preparation process is simple and easy to operate.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of composite material manufacturing, and particularly relates to the application in the fields of aero-engine parts, satellite structures, electronics, etc., and specifically relates to a short-cut fiber reinforced resin matrix composite material and a preparation method thereof. BACKGROUND

[0002] The resin matrix composite material is widely used in industrial fields due to its light weight, high strength, corrosion resistance, etc., and the short-cut fiber reinforced resin matrix composite material has the advantages of low cost and easy processing, etc., but the initial short-cut fiber reinforced resin matrix composite material has the problems of uneven dispersion and weak interface bonding; with the development of research, a coupling agent is selected for fiber surface treatment at the interface to enhance the interface bonding strength. Specifically, the fiber modification effect of the coupling agent in the low-temperature and medium-temperature resin matrix composite material system such as epoxy and phenolic is good, but in the high-temperature resin such as the polyimide resin matrix composite material system, the high temperature required for resin curing makes the conventional coupling agent ineffective.

[0003] The polyimide resin has the advantages of extremely high temperature resistance (long-term use temperature > 250℃), excellent corrosion resistance, excellent electrical insulation performance, etc.; however, the pure polyimide resin is brittle and needs to be reinforced by fibers to improve the toughness. When the fiber reinforced polyimide resin is prepared by the traditional method, the problems easily occur, such as incomplete solvent volatilization, uneven fiber distribution, and poor interface bonding between the fiber and the resin, which further affect the mechanical strength and toughness of the composite material.

[0004] Therefore, the present application is provided. SUMMARY

[0005] The present application aims to overcome the above-mentioned shortcomings of the prior art, and provides a short-cut fiber reinforced resin matrix composite material and a preparation method thereof. The present application can improve the mechanical strength and toughness of the material while maintaining excellent electrical insulation performance and high temperature resistance of the composite material.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions: On the one hand, the present application provides a short-cut fiber reinforced resin matrix composite material, which comprises the following components by mass fraction: short-cut fiber 10-20 parts, resin matrix 80-90 parts, and modifier 0.2-1 part. The modifier is compounded by ester type impregnant, flexible polyimide and solvent.

[0007] Further, the resin matrix is a polyimide resin, and the polyimide resin is an acetylene end group polyimide resin or an ether anhydride type polyimide resin.

[0008] Further, the short-cut fiber is glass fiber, and the fiber length is 2-10 mm.

[0009] Further, the mass ratio of the ester type infiltrant to the flexible polyimide is 6:1, and the solvent is N-methyl pyrrolidone; The mass fraction of the ester type infiltrant and the flexible polyimide in the modifier is 20% to 40%.

[0010] In another aspect, the present application provides a preparation method of a short fiber reinforced resin matrix composite material, based on the short fiber reinforced resin matrix composite material as described above, comprising the following steps: S1, drying treatment of the polyimide resin of the resin matrix; S2, ultrasonic cleaning of the short fiber with heated deionized water to clean the water-based epoxy sizing agent remaining on the surface of the short fiber, drying in a low-temperature oven after cleaning, and then ultrasonic soaking of the dried short fiber in a modifier, followed by drying in a high-temperature oven to obtain modified short fiber; S3, proportioning of the polyimide resin in S1 and the modified short fiber in S2, uniform mixing by a stirring device to obtain a molding material; S4, hot molding of the molding material in S3 by a hot molding machine.

[0011] Further, in S1, when the polyimide resin is acetylene-terminated polyimide resin, S101 is performed, and when the polyimide resin is ether anhydride type polyimide resin, S102 is performed; specifically: S101, placing the acetylene-terminated polyimide resin into an oven, heating to 270 to 330℃, and holding for 105 to 135 min; S102, placing the ether anhydride type polyimide resin into an oven, heating to 200 to 260℃, and holding for 105 to 135 min.

[0012] Further, in S2, the temperature of the heated deionized water is 80 to 100℃, and the ultrasonic cleaning time is 30 to 60 min; the drying temperature of the low-temperature oven is 90 to 100℃, and the drying time is 240 to 360 min; The ultrasonic soaking time is 5 to 10 min, and the soaking temperature is 80 to 100℃; The drying temperature of the high-temperature oven is 280 to 320℃, and the drying time is 20 to 30 min.

[0013] Further, in S3, the mass ratio of the polyimide resin to the modified short fiber is (4 to 9):1, the stirring device rotation speed is 24000 to 26000 rpm, the stirring time each time is 40 to 80 s, and the interval time between each stirring is 15 to 20 min.

[0014] Specifically, the multiple interval stirring is arranged because a large amount of heat is generated in a short time when the device is operated at a high rotating speed, and the stirring is completed in multiple times to cool the device, and the device cooling can be natural cooling or water cooling.

[0015] Further, in S4, before using the hot molding machine, the surface of the molding die is cleaned and a release agent is applied, wherein the application condition of the release agent is room temperature. The release agent is a mixed release agent, and the surface of the molding die is first coated with a silicone release agent, and after the silicone release agent is dried, graphite powder is uniformly applied on the surface of the silicone release agent.

[0016] Specifically, the commonly used silicone oil release agent for molding is prone to failure in the curing process of the powder polyimide resin, so a layer of graphite powder is applied after the commonly used silicone oil release agent is applied to ensure smooth demolding of the formed composite material.

[0017] Further, in S4, during the hot molding process, when the polyimide resin is an acetylene-terminated polyimide resin, S401 is performed; when the polyimide resin is an ether anhydride type polyimide resin, S402 is performed; specifically: S401, the curing temperature of the acetylene-terminated polyimide resin is 370-400℃, the curing time is 110-130min, and the molding pressure is 140-160MPa; S402, the curing temperature of the ether anhydride type polyimide resin is 340-395℃, the curing time is 15-45min, and the molding pressure is 15-35MPa.

[0018] Compared with the prior art, the present application has the following beneficial effects: (1) The short fiber reinforced resin matrix composite material provided by the present application has the characteristics of light weight, high strength and electrical insulation. According to test verification, the density of the short fiber reinforced resin matrix composite material is less than 1.5g / cm 3 , the room temperature bending strength can reach 180MPa according to GB / T 9341 test, the compression strength can reach 420MPa according to GB / T 1041 test, and the dielectric constant at 50Hz frequency is less than 4 and the dielectric loss tangent value is less than 0.003 according to GB / T 1409 test.

[0019] (2) The application provides a preparation method of a short-cut fiber reinforced resin-based composite material, a modifier solution is used to perform surface modification on the short-cut fiber, high-temperature-resistant polyimide layers are formed on the surface of the short-cut fiber while filling the surface defects of the fiber (namely modified short-cut fiber), in the process of reinforcing the polyimide resin, the modified short-cut fiber is combined with the polyimide resin as a matrix to form a chemical bond, the combination of the short-cut fiber and the matrix resin is enhanced, and the problems of low strength and poor toughness of pure polyimide resin are greatly improved.

[0020] (3) The application provides a preparation method of a short-cut fiber reinforced resin-based composite material, the resin is solid polyimide resin, and the polyimide resin is pretreated (dried treatment in an oven after water washing) before mixing, so that water contained in the resin is removed and most of the imidization process of the resin is completed, and the cyclic water and other small molecules possibly generated in the curing process are reduced; in addition, the polyimide resin and the modified short-cut fiber are dispersed at a high speed, so that the problems of uneven solvent volatilization and uneven fiber distribution in the traditional mixing process are avoided. In addition, the acetylene-terminated polyimide resin or the ether anhydride type polyimide resin has excellent thermal stability, can withstand a relatively high temperature without degradation or deformation in the hot molding process, and is beneficial to maintaining the performance of the resin. Secondly, due to the existence of acetylene end groups in the acetylene-terminated polyimide resin and the existence of ether anhydride in the ether anhydride type polyimide resin, the acetylene-terminated polyimide resin and the ether anhydride type polyimide resin have relatively high reactivity in the hot molding process, and the curing reaction can be completed in a relatively short time, so that the production efficiency is greatly improved. Finally, the acetylene-terminated polyimide resin and the ether anhydride type polyimide resin have good compatibility with the modified short-cut fiber in the hot molding process, so that a strong interfacial bonding force is formed between the resin matrix and the fiber, and the mechanical properties of the composite material are improved.

[0021] (4) The application provides a preparation method of a short-cut fiber reinforced resin-based composite material, a hot molding technology with high maturity is adopted, the composite material has good molding effect, the product thickness can be controlled according to the feeding amount, and the preparation process is simple and easy to operate. BRIEF DESCRIPTION OF DRAWINGS

[0022] The drawings incorporated into the specification and constituting a part of the specification are used together with the specification to explain the principles of the application.

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows, and obviously, other drawings can be obtained by those skilled in the art without any creative labor.

[0024] Figure 1The internal structure diagram of the resin-based composite material of the embodiment 1 of the present application; Figure 2 The flowchart of the preparation method of the present application. DETAILED DESCRIPTION

[0025] The exemplary embodiments will be described in detail herein below, and the embodiments described in the following exemplary embodiments do not represent all the embodiments consistent with the present application. Rather, they are merely examples consistent with some aspects of the present application as detailed in the appended claims.

[0026] Embodiment 1 The present application provides a short fiber reinforced resin-based composite material, comprising the following components by mass fraction: glass fiber with a length of 3 mm: 19 parts, acetylene end group polyimide resin: 80 parts, modifier: 1 part. The modifier is compounded by ester type infiltrant, flexible polyimide and solvent.

[0027] Specifically, the mass ratio of the ester type infiltrant to the flexible polyimide is 6:1, the solvent is N-methyl pyrrolidone, and the mass fraction of the ester type infiltrant and the flexible polyimide in the modifier is 40%.

[0028] On the other hand, referring to Figure 2 The present embodiment provides a preparation method of a short fiber reinforced resin-based composite material, based on the short fiber reinforced resin-based composite material as described above, comprising the following steps: S1, placing the acetylene end group polyimide resin in an oven for drying treatment, specifically, heating to 300℃ with the furnace, and keeping for 120 min; S2, ultrasonic cleaning the glass fiber with deionized water heated to 80℃, the cleaning time is 30 min, cleaning the water-based epoxy sizing agent remaining on the surface of the glass fiber, after cleaning, drying in a low temperature oven at 100℃ for 360 min, then ultrasonic modification of the dried glass fiber in a modifier solution with a mass fraction of 40% (i.e. modifier) for 10 min, the temperature of the modifier solution is 100℃, and then drying in a high temperature oven at 300℃ for 30 min, to obtain modified short fibers; S3, mixing the acetylene end group polyimide resin in S1 and the modified short fibers in S2 in a high-speed pulverizer according to a mass ratio of 4:1, setting the rotation speed to 25000 rpm, the stirring time is 60 s, the equipment stops cooling for 15 min, and repeating 3 times, to obtain a mold pressing material; S4, the surface of the mold pressing mold is cleaned, after cleaning the mold, first coating 2 times of silicone release agent on the surface of the mold at room temperature, each interval is 15 min, 2 times of coating is completed and is placed for 30 min; in order to prevent the failure of silicone release agent, after the surface drying of the release agent, evenly coating a layer of 1000 mesh graphite powder; then the mold pressing material in S3 is put into the mold to carry out mold pressing forming.

[0029] Specifically, in the hot mold pressing forming process, the curing temperature of the acetylene end group polyimide resin is 390 DEG C, the curing time is 120 min, and the forming pressure is 150 MPa.

[0030] Example 2 The application provides a short fiber reinforced resin-based composite material, which comprises the following components by mass: 10.5 parts of glass fiber with a length of 5 mm, 89 parts of acetylene end group polyimide resin, and 0.5 parts of modifier. The modifier is composed of ester type impregnating agent, flexible polyimide and solvent.

[0031] Specifically, the mass ratio of the ester type impregnating agent to the flexible polyimide is 6:1, the solvent is N-methyl pyrrolidone, and the mass fraction of the ester type impregnating agent and the flexible polyimide in the modifier is 30%.

[0032] On the other hand, the application provides a preparation method of a short fiber reinforced resin-based composite material, which is based on the short fiber reinforced resin-based composite material as described above and comprises the following steps: S1, acetylene end group polyimide resin is placed in an oven for drying treatment, specifically, the oven is heated to 270 DEG C, and the temperature is kept for 135 min; S2, the glass fiber is ultrasonically cleaned with deionized water heated to 90 DEG C, the cleaning time is 45 min, after cleaning, the glass fiber is dried in a low-temperature oven at 95 DEG C for 300 min, then the dried glass fiber is ultrasonically modified in a modifier solution for 8 min, the temperature of the modifier solution is 90 DEG C, and then the glass fiber is dried in a high-temperature oven at 280 DEG C for 20 min, to obtain modified short fibers; S3, the acetylene end group polyimide resin in S1 and the modified short fibers in S2 are mixed in a high-speed pulverizer according to a mass ratio of 9:1, the rotating speed is set to 24000 rpm, the stirring time is 80 s, the equipment is stopped and cooled for 18 min, and the operation is repeated for 3 times, to obtain mold pressing material; S4, the surface of the mold pressing mold is cleaned, after cleaning the mold, first coating 2 times of silicone release agent on the surface of the mold at room temperature, each interval is 15 min, 2 times of coating is completed and is placed for 30 min; in order to prevent the failure of silicone release agent, after the surface drying of the release agent, evenly coating a layer of 1000 mesh graphite powder; then the mold pressing material in S3 is put into the mold to carry out mold pressing forming.

[0033] In the hot molding process, the curing temperature of the acetylene-terminated polyimide resin is 370℃, the curing time is 130 min, and the molding pressure is 140 MPa.

[0034] Embodiment 3 In one aspect, the present application provides a short fiber reinforced resin-based composite material, comprising the following components by mass fraction: glass fiber with a length of 2 mm: 15 parts, acetylene-terminated polyimide resin: 84.8 parts, modifier: 0.2 parts. The modifier is compounded by an ester type infiltrant, a flexible polyimide and a solvent.

[0035] Specifically, the mass ratio of the ester type infiltrant to the flexible polyimide is 6:1, the solvent is N-methyl pyrrolidone, and the mass fraction of the ester type infiltrant and the flexible polyimide in the modifier is 20%.

[0036] In another aspect, the present embodiment provides a preparation method of a short fiber reinforced resin-based composite material, based on the short fiber reinforced resin-based composite material as described above, comprising the following steps: S1, placing the acetylene-terminated polyimide resin in an oven for drying treatment, specifically, heating to 300℃, and keeping for 120 min; S2, ultrasonic cleaning the glass fiber with deionized water heated to 100℃, cleaning time is 60 min, after cleaning, drying in a low temperature oven at 90℃ for 240 min, then ultrasonic modification in a modifier solution for 5 min, the temperature of the modifier solution is 80℃, then drying in a high temperature oven at 320℃ for 25 min, to obtain modified short fibers; S3, feeding the acetylene-terminated polyimide resin in S1 and the modified short fibers in S2 into a high-speed pulverizer according to a mass ratio of 7:1, setting the rotation speed to 26000 rpm, stirring time is 40 s, stopping the equipment and cooling for 20 min, repeating 3 times, to obtain a molding material; S4, cleaning the surface of the molding mold, after cleaning the mold, first applying silicone release agent on the surface of the mold at room temperature for 2 times, each time interval is 15 min, 3 times of application is completed, and then standing for 30 min; after the surface of the release agent is dry, evenly applying 1000 mesh graphite powder; then feeding the molding material in S3 into the mold for molding.

[0037] Specifically, in the hot molding process, the curing temperature of the acetylene-terminated polyimide resin is 400℃, the curing time is 130 min, and the molding pressure is 160 MPa.

[0038] Embodiment 4 The difference between the present embodiment and embodiment 1 is: (1) The resin-based composite material comprises the following components by mass: glass fiber with a length of 10 mm: 19 parts, ether anhydride type polyimide resin: 80 parts, modifier: 1 part; (2) S1, the ether anhydride type polyimide resin is placed in an oven for drying treatment, specifically, the oven is heated to 230°C, and kept for 120 minutes; S3, the ether anhydride type polyimide resin in S1 and the modified short-cut fiber in S2 are mixed in a high-speed pulverizer according to a mass ratio of 4:1; Specifically, in the hot mold pressing forming process, the curing temperature of the ether anhydride type polyimide resin is 365°C, the curing time is 30 minutes, and the forming pressure is 25 MPa.

[0039] Example 5 The difference between this embodiment and Example 2 is: (1) The resin-based composite material comprises the following components by mass: glass fiber with a length of 5 mm: 10.5 parts, ether anhydride type polyimide resin: 89 parts, modifier: 0.5 part; (2) S1, the ether anhydride type polyimide resin is placed in an oven for drying treatment, specifically, the oven is heated to 200°C, and kept for 135 minutes; S3, the ether anhydride type polyimide resin in S1 and the modified short-cut fiber in S2 are mixed in a high-speed pulverizer according to a mass ratio of 4:1; Specifically, in the hot mold pressing forming process, the curing temperature of the ether anhydride type polyimide resin is 340°C, the curing time is 45 minutes, and the forming pressure is 15 MPa.

[0040] Example 6 The difference between this embodiment and Example 3 is: (1) The resin-based composite material comprises the following components by mass: glass fiber with a length of 2 mm: 14.8 parts, ether anhydride type polyimide resin: 85 parts, modifier: 0.2 part; (2) S1, the ether anhydride type polyimide resin is placed in an oven for drying treatment, specifically, the oven is heated to 260°C, and kept for 105 minutes; S3, the ether anhydride type polyimide resin in S1 and the modified short-cut fiber in S2 are mixed in a high-speed pulverizer according to a mass ratio of 7:1; Specifically, in the hot mold pressing forming process, the curing temperature of the ether anhydride type polyimide resin is 370°C, the curing time is 15 minutes, and the forming pressure is 35 MPa.

[0041] In order to prove the efficacy of the present application, the mechanical properties and medium dielectric constant of Examples 1-6 were tested at room temperature, the room temperature bending strength was tested according to GB / T 9341, the compression strength was tested according to GB / T 1041, and the 50Hz frequency dielectric constant and dielectric loss tangent were tested according to GB / T 1409. The test results are shown in Tables 1 and 2.

[0042] Table 1 Room temperature mechanical properties Table 2 50Hz frequency dielectric constant and dielectric loss tangent As can be seen from Tables 1 and 2, the short fiber reinforced polyimide resin composite material developed in the present application has good mechanical properties and insulation performance.

[0043] The above description is merely a specific implementation of the present application, enabling a person skilled in the art to understand or implement the present application. Various modifications to these examples will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other examples without departing from the spirit or scope of the present application.

[0044] It should be understood that the present application is not limited to the above-described and that various modifications and changes can be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A short fiber-reinforced resin matrix composite, characterized by, The short-cut fiber reinforced resin matrix composite material comprises the following components in parts by mass: 10-20 parts of short-cut fiber, 80-90 parts of resin matrix, and 0.2-1 part of modifier. The modifier is compounded from ester type impregnant, flexible polyimide and solvent.

2. The short-cut fiber reinforced resin-based composite material of claim 1, wherein, The resin matrix is polyimide resin, and the polyimide resin is acetylene end group polyimide resin or ether anhydride type polyimide resin.

3. The short-cut fiber reinforced resin-based composite of claim 1, wherein, The short-cut fiber is glass fiber, and the fiber length is 2-10 mm.

4. The short-cut fiber reinforced resin-based composite of claim 1, wherein, The mass ratio of the ester type impregnant to the flexible polyimide is 6:1, and the solvent is N-methyl pyrrolidone. The mass fraction of the ester type impregnant and the flexible polyimide in the modifier is 20%-40%.

5. A method of producing a short fiber-reinforced resin matrix composite material, characterized by, The short-cut fiber reinforced resin matrix composite material based on any one of claims 1-4 comprises the following steps: S1, drying treatment of the polyimide resin of the resin matrix; S2, ultrasonic cleaning of the short-cut fiber with heated deionized water to clean the water-based epoxy sizing agent remaining on the surface of the short-cut fiber, drying in a low-temperature oven after cleaning, ultrasonic soaking of the dried short-cut fiber in the modifier, and then drying through a high-temperature oven to obtain modified short-cut fiber; S3, proportioning of the polyimide resin in S1 and the modified short-cut fiber in S2, uniform mixing through a stirring device to obtain a molding material; S4, hot molding of the molding material in S3 through a hot molding machine.

6. The production method according to claim 5, wherein In S1, when the polyimide resin is acetylene end group polyimide resin, S101 is performed, and when the polyimide resin is ether anhydride type polyimide resin, S102 is performed; specifically: S101, placing the acetylene end group polyimide resin into an oven, heating to 270-330℃, and keeping the temperature for 105-135 min; S102, placing the ether anhydride type polyimide resin into an oven, heating to 200-260℃, and keeping the temperature for 105-135 min.

7. The preparation method according to claim 5, characterized in that, In S2, the temperature of the heated deionized water is 80-100℃, and the ultrasonic cleaning time is 30-60 min; the drying temperature of the low-temperature oven is 90-100℃, and the drying time is 240-360 min; The ultrasonic soaking time is 5-10 min, and the soaking temperature is 80-100℃; The drying temperature of the high-temperature oven is 280-320℃, and the drying time is 20-30 min.

8. The preparation method according to claim 5, characterized in that, In S3, the mass ratio of the polyimide resin to the modified short-cut fiber is (4-9):1, the stirring device rotation speed is 24,000-26,000 rpm, the stirring time is 40-80 s each time, and the interval time is 15-20 min.

9. The preparation method according to claim 5, characterized in that, In S4, before using the hot molding machine, the surface of the molding die is cleaned and lubricant is applied, and the application conditions of the lubricant are room temperature; The lubricant is a mixed lubricant, and the surface of the molding die is first coated with silicone lubricant, and then graphite powder is uniformly coated on the surface after the silicone lubricant is dry.

10. The method of claim 5, wherein, In S4, during the hot molding process, when the polyimide resin is acetylene end group polyimide resin, S401 is performed; when the polyimide resin is ether anhydride type polyimide resin, S402 is performed; specifically: S401、acetylene end-capped polyimide resin curing temperature is 370~400℃, curing time is 110~130min, molding pressure is 140~160MPa; S402、ether anhydride type polyimide resin curing temperature is 340~395℃, curing time is 15~45min, molding pressure is 15~35MPa.

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