A chopped carbon fiber reinforced blended modified phenolphthalein polyarylether nitrile ketone resin composite material and preparation method thereof

Abstract

The present invention relates to a polymer synthesis process and a carbon fiber composite material preparation process, and in particular to a short-cut carbon fiber reinforced blended modified phenolphthalein polyarylether nitrile ketone resin composite material and a preparation method thereof. The technical points are as follows: a resin with excellent processing fluidity is synthesized as an auxiliary agent to reduce the melt viscosity of a matrix resin; a sizing agent resin with good film-forming properties and containing polar groups is synthesized for surface modification of carbon fibers; the modified carbon fibers and the matrix resin are melt-blended through a twin-screw extruder to prepare a composite material. The present invention provides a sizing short-cut carbon fiber reinforced blended modified phenolphthalein polyarylether nitrile resin composite material and a preparation method thereof, which imparts good processing fluidity to the matrix resin, strengthens the degree of impregnation between the fiber and the resin, and at the same time, the sizing agent enhances the interface strength between the fiber and the resin, and the mechanical properties are significantly improved. It can be widely used in the fields of transportation vehicles, sports equipment, etc.

Description

Technical Field

[0001] The invention relates to the technical field of polymer synthesis and blending modification, and in particular to a chopped carbon fiber reinforced blending modified phenolphthalein polyarylether nitrile ketone resin composite material and a preparation method thereof. Background Art

[0002] Amorphous poly(arylether nitrile ketone) (PEK-CN) resin is a ternary copolymer prepared by nucleophilic substitution polycondensation reaction of phenolphthalein, 2,6-dichlorobenzonitrile and 4,4'-difluorobenzophenone as raw materials. PEK-CN has excellent thermal and mechanical properties. g 230℃~255℃, thermal weight loss T 5％ At temperatures above 480°C, the tensile strength is above 80MPa. At the same time, due to the presence of the active group nitrile, PEK-CN resin becomes an ideal matrix material for preparing carbon fiber reinforced composite materials. However, due to the strong polarity and high molecular weight of PEK-CN resin, the melt viscosity is large and the processing fluidity is poor, which makes the resin poor in the wettability and coating of carbon fiber, and it is easy to produce defects at the interface. There are no polar groups on the surface of carbon fiber that can interact with PEK-CN resin, resulting in poor adhesion between carbon fiber and resin, affecting the transfer of load, and then leading to a decrease in mechanical properties.

[0003] In the prior art, there is no auxiliary agent and suitable sizing agent for PEK-CN resin for preparing carbon fiber composite materials. The present invention successfully reduces the melt viscosity and improves the carbon fiber wettability by adding a self-synthesized auxiliary resin to the modified PEK-CN resin; at the same time, the surface of the carbon fiber is modified by coating the sizing agent to improve the interface strength. This fills the gap of PEK-CN resin in the field of short-cut carbon fiber composite materials.

[0004] Polymer blending refers to the process of mixing two or more polymers into a macroscopically uniform material. Blending modification is the simplest and most effective method of polymer modification. Blending and modifying polymers with different properties can eliminate the weaknesses of a single polymer component, enable the blends to complement each other in performance, develop new materials with excellent comprehensive performance, and greatly improve the performance of polymers. For example, blending modification can improve the molding and processing properties of polymers, and provide a new way for the processing and molding of some polymers with high melting points and high melt viscosity, especially in the field of special engineering plastics. Most commercialized special engineering plastics are difficult to mold and process due to their high melting points, poor melt fluidity, and lack of suitable solvents, which can be easily achieved through blending.

[0005] Carbon fiber can be divided into polyacrylonitrile-based carbon fiber and asphalt-based carbon fiber according to the different precursor fibers, and the output ratio of the two is about 6:1. At present, short carbon fiber of about 5mm is often used to reinforce thermoplastic plastics in the market for carbon fiber reinforced thermoplastics. Due to the low density of carbon fiber itself and the few functional groups on the surface of carbon fiber, if the surface of carbon fiber is not sizing, a large amount of hair will be produced in the subsequent processing such as production and transportation, which will have a certain impact on the safety of production workshop staff and machine operation in the production workshop. At the same time, due to the low stacking density of short carbon fiber, short carbon fiber cannot be evenly fed in the feeder, and due to the few functional groups on the surface structure of carbon fiber, the bonding strength with thermoplastic plastic is poor. In order to avoid the above shortcomings, sizing the carbon fiber is the best treatment method.

[0006] One of the most mature surface treatment technologies for carbon fiber is to coat the surface of the carbon fiber with a sizing agent. This method is also a supporting surface treatment technology in the commercial carbon fiber production process. Sizing agents are usually divided into two types: solution type and emulsion type. Solution type sizing agents refer to epoxy resins, unsaturated polyesters, polyurethanes, polyaryletherketones, etc. dissolved in low-boiling point volatile solvents to form a dilute solution of a certain concentration. These resins have the same or similar structure as the matrix resin. The solution-type sizing agent can improve the compatibility between the fiber and the resin, improve the wettability of the carbon fiber, and avoid the brittle fracture of the carbon fiber. The solution-type carbon fiber sizing agent has the characteristics of simple formula, ready-to-use, low surface tension, strong penetration ability, and the ability to infiltrate the inside of the fiber bundle. Summary of the invention

[0007] In view of the problems of high melt viscosity and low interface strength between resin and fiber in the preparation of carbon fiber reinforced composite materials by phenolphthalein poly (arylether nitrile ketone) (PEK-CN) resin in the prior art, the purpose of the present invention is to provide a method for preparing a sizing short carbon fiber reinforced blended modified PEK-CN resin composite material. By synthesizing an auxiliary resin and blending it with PEK-CN, the processing fluidity of PEK-CN is improved, a sizing agent resin is synthesized, the interface bonding ability between the resin and the fiber is strengthened, and the mechanical strength of the composite material is improved.

[0008] To achieve the above object: the present invention provides a method for preparing a sizing chopped carbon fiber reinforced blended modified PEK-CN composite material, comprising the following steps:

[0009] S1. Preparation of sized carbon fiber: The continuous carbon fiber is slowly passed through a desizing tank filled with acetone to remove the original epoxy resin on the surface of the carbon fiber. The desizing carbon fiber is then passed through an impregnation tank filled with sizing liquid for sizing, and then passed through a high-temperature oven at 260°C to remove the solvent. After being chopped, the sized continuous carbon fiber is finally obtained.

[0010] S2. Fully mix the sizing chopped carbon fiber, phenolphthalein polyarylether nitrile ketone resin and auxiliary resin obtained in S1, add the blend into a twin-screw extruder, melt-blend and extrude granulate at 330° C. to 350° C. to obtain a sizing chopped carbon fiber reinforced blended modified phenolphthalein polyarylether nitrile ketone resin composite material.

[0011] Furthermore, the preparation steps of the auxiliary resin are as follows: adding biphenol, phenolphthalein, 4,4'-difluorobenzophenone and sodium carbonate into a container, adding sulfolane as a solvent and xylene as a water-carrying agent, introducing nitrogen, stirring at 190°C to 210°C for 2 to 3 hours, removing xylene after ensuring sufficient salt formation, heating to 220°C to 230°C and stirring for 2 to 3 hours, precipitating in a mixed solution of water and ethanol, crushing, boiling and washing, and vacuum drying to obtain auxiliary resin powder.

[0012] Furthermore, in the preparation of the auxiliary resin, the solid content of the reaction system is 20% to 25%; the molar ratio of biphenol, phenolphthalein, 4,4'-difluorobenzophenone and sodium carbonate is 0.5 to 0.7: 0.3-0.5: 1.01-1.06: 1.5 to 2; the volume ratio of xylene to cyclopentane sulfone is 1-3: 4; and the volume ratio of water to ethanol in the mixed solution of water and ethanol is 5-7: 3-5.

[0013] Furthermore, the preparation steps of the sizing agent solution are as follows: adding biphenol, 2,6-dichlorobenzonitrile, 4,4'-difluorobenzophenone and potassium carbonate into a container, adding N,N-dimethylpyrrolidone as a solvent and xylene as a water-carrying agent, introducing nitrogen, stirring at 160°C to 170°C for 2 to 3 hours, and removing xylene after ensuring sufficient salt formation; then heating to 180°C to 185°C and stirring for 2 to 3 hours, discharging the material in a mixed solution of water and ethanol to obtain a sizing agent resin; dissolving the sizing agent resin in N,N-dimethylpyrrolidone to prepare a sizing agent solution, wherein the solid content of the resin in the sizing agent solution is 0.5% to 10%, preferably 2-6%, for example 2%, 4%, 6%.

[0014] Furthermore, the auxiliary resin powder is blended with the PEK-CN resin powder by a mixer to obtain a uniformly dispersed blend. The sizing short-cut carbon fiber is mixed with the blend, and the carbon fiber is uniformly dispersed in the blended powder, and then the mixture of the three is added to a high-temperature twin-screw extruder for melt blending and extrusion to obtain a sizing short-cut carbon fiber reinforced blended modified PEK-CN resin composite material.

[0015] Further, the continuous carbon fiber is desized by passing through a desizing tank filled with acetone at a speed of 0.8 to 1 m / min, and the desized carbon fiber is sized by passing through an immersion tank filled with a sizing agent solution at a speed of 0.8 to 1 m / min at room temperature.

[0016] Furthermore, the sized continuous carbon fibers are cut into chopped carbon fibers of 3 to 5 mm.

[0017] Furthermore, the mass percentage of the chopped carbon fibers in the mixture is 3% to 15%, preferably 3-9%, for example 3%, 6%, 9%; the mass ratio of the phenolphthalein polyarylether nitrile ketone resin to the auxiliary resin is 8 to 5:2-5, for example 8:2, 7:3, 6:4, 5:5.

[0018] Furthermore, the parameters of the twin-screw extruder during extrusion are: filler zone temperature 250-270°C, zone 1 temperature 330-350°C, zone 2 temperature 330-350°C, die head temperature 330-350°C, and rotation speed 10-20r / min.

[0019] The present invention synthesizes a resin with excellent processing fluidity as an auxiliary agent for reducing the melt viscosity of a matrix resin; synthesizes a sizing agent resin with good film-forming property and containing polar groups for surface modification of carbon fibers; and then melt-blending the modified carbon fibers and the matrix resin through a twin-screw extruder to prepare a composite material.

[0020] Due to the adoption of the above technical scheme, compared with the prior art, the present invention has the following advantages: ① The addition of the auxiliary resin successfully improves the processing fluidity of the matrix resin PEK-CN, strengthens the degree of impregnation between the fiber and the resin, reduces the melt viscosity of the resin, and enables the resin to better coat the carbon fiber and increase the interface contact surface; ② The coating of the carbon fiber by the sizing agent improves the bundling of the carbon fiber, introduces the active group nitrile group on the surface of the carbon fiber, improves the interface ability between the carbon fiber and the matrix resin, and thus improves the mechanical strength of the composite material. It can be widely used in the fields of transportation, sports equipment, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The synthetic route of the auxiliary resin used in the present invention;

[0022] Figure 2 The synthetic route of the sizing agent resin used in the present invention;

[0023] Figure 3 This is the infrared spectrum of the synthesized auxiliary resin;

[0024] Figure 4 is the infrared spectrum of the synthesized sizing agent resin;

[0025] Figure 5 The picture is a microscopic morphology of the tensile section of the composite material (30% additive content) after the auxiliary resin and the modified PEK-CN are blended under a scanning electron microscope;

[0026] Figure 6The process flow chart of preparing sized carbon fiber in the present invention;

[0027] Figure 7 is the tensile strength of the sizing chopped carbon fiber modified blended modified PEK-CN resin composite material in the present invention;

[0028] Figure 8 This is a picture of the microscopic morphology of the tensile section of the modified blended PEK-CN resin composite material prepared in Example 1 of the present invention (the solid content of the sizing agent solution is 2%, and the carbon fiber content is 6%) under a scanning electron microscope. DETAILED DESCRIPTION

[0029] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, a sizing chopped carbon fiber reinforced blended modified PEK-CN resin composite material and a preparation method thereof proposed in accordance with the present invention, its specific implementation method, characteristics and effects are described in detail as follows.

[0030] The structure of the phenolphthalein polyarylether nitrile ketone resin in the following examples is as follows:

[0031]

[0032] , m:n=7:3, concentrated viscosity in DMAC 0.45, melt index of 5KG at 350°C 2.4g / min.

[0033] Example 1

[0034] A method for preparing a sizing chopped carbon fiber reinforced blended modified PEK-CN resin composite material comprises the following steps:

[0035] Step 1, synthesis of auxiliary resin: add 19.1g phenolphthalein, 16.76g biphenyl phenol, 34.69g 4,4'-difluorobenzophenone and 31.8g sodium carbonate into a three-necked flask, add 215g sulfolane as solvent and 70ml xylene as water-carrying agent. The molar ratio of phenolphthalein to biphenyl phenol is 4:6, and the solid content of the reaction system is 25%. Slowly heat to 190°C and keep for two hours, then heat to 220°C and keep for two hours. Pour the solution into a mixed solution of deionized water and ethanol (ethanol volume fraction 30%) and soak for 24 hours. After crushing the resin, boil and wash 8 times, and then dry it in a vacuum oven at 180°C for 24 hours.

[0036] Step 2, synthesis of sizing agent resin: 27.93g of biphenyl diphenol, 22.94g of 2,6-dichlorobenzonitrile, 7.07g of 4,4'-difluorobenzophenone and 24.88g of potassium carbonate are added to a three-necked flask, and then 150g of N,N-dimethylpyrrolidone is added as a solvent and 120ml of xylene is added as a water-carrying agent. The molar ratio of 2,6-dichlorobenzonitrile to 4,4'-difluorobenzophenone is 8:2, and the solid content of the reaction system is 25%. Slowly heat to 160°C and keep for two hours, and then heat to 180°C and keep for two hours. Pour the solution into a mixed solution of deionized water and ethanol (ethanol volume fraction 30%) and soak for 24 hours. After that, crush the resin and boil and wash it 8 times, and then dry it in a vacuum oven at 180°C for 24 hours.

[0037] Step 3, preparation of a solution-type sizing agent solution: dissolving the dried sizing agent resin powder in N,N-dimethylpyrrolidone to prepare sizing agent solutions with solid contents of 2%, 4% and 6% respectively.

[0038] Step 4: Carbon fiber sizing process: Continuous carbon fiber (from Japan Toray, model T700) first passes through two desizing tanks filled with acetone at a speed of 1m / min to remove the original epoxy resin on the surface of the carbon fiber. At room temperature, it passes through an immersion tank filled with the above sizing agent solution at a speed of 1m / min for sizing, and then passes through three high-temperature ovens at 260°C to remove N,N-dimethylpyrrolidone in the solution. Finally, the continuous carbon fiber is cut into 3-5mm short carbon fibers.

[0039] Step 5, mixing: PEK-CN resin powder, auxiliary resin and the above-mentioned short-cut carbon fiber are blended in a mixer to obtain a uniformly mixed blend, wherein the mass ratio of PEK-CN to the auxiliary is 7:3, the mass percentage of the short-cut carbon fiber is 6%, and the mass percentage of the total of PEK-CN and the auxiliary is 94%.

[0040] Step 6, preparation of composite materials: set the temperature of each zone of the twin-screw extruder as follows: 270°C for the filling zone; 330°C for the first zone, 330°C for the second zone, and 330°C for the die head, and keep the temperature for 30 minutes. Then add the above blend to the filling port, and set the speed to 10r / min. Obtain the melt-blended sizing short-cut carbon fiber reinforced blended modified PEK-CN resin composite material.

[0041] Example 2

[0042] The operation steps are the same as those of Example 1, except that the solid content of the sizing agent solution is 2%, and the mass ratios of PEK-CN to the auxiliary agent are 8:2 and 6:4, respectively.

[0043] The melt index of the PEK-CN resin prepared in Example 1 and Example 2 and the PEK-CN resin composite material prepared after blending and modification are shown in Table 1. It is observed that the addition of the auxiliary resin significantly improves the melt viscosity and processing fluidity of the matrix resin. The microscopic morphology of the tensile section of the sizing short carbon fiber reinforced blending and modification PEK-CN resin composite material under a scanning electron microscope is shown in Table 1. Figure 8 As shown in the figure, it is observed that the chopped carbon fibers are evenly dispersed in the resin, and the interface between the carbon fibers and the resin is tight and has strong coverage. The tensile strength of the matrix resin and the composite material is shown in Figure 7 As shown, it was observed that the mechanical strength of the blended modified composite material with the addition of sized carbon fiber increased by 105%. It can be seen that the sized short carbon fiber reinforced blended modified PEK-CN resin composite material provided by the present invention effectively improves the wettability of the resin to the carbon fiber, strengthens the interface strength between the resin and the carbon fiber, and thus improves the mechanical strength of the composite material.

[0044] Table 1

[0045]

[0046] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been shown as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with the profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a chopped carbon fiber reinforced blended modified phenolphthalein polyarylether nitrile ketone resin composite material, characterized in that: The steps include: S1, placing a continuous carbon fiber bundle in a sizing device, desizing it through a desizing tank filled with acetone, sizing the desizing carbon fiber through an impregnation tank filled with a sizing agent solution, and then drying it in a high-temperature oven at 240° C. to 280° C. to remove the solvent, and chopping it to obtain sizing short-cut carbon fiber; S2, fully mixing the sizing short-cut carbon fiber, phenolphthalein polyarylether nitrile ketone resin and auxiliary resin obtained in S1, adding the blend into a twin-screw extruder, and melt-blending and extruding granulation at 330° C. to 350° C. to obtain a sizing short-cut carbon fiber reinforced blended modified phenolphthalein polyarylether nitrile ketone resin composite material; The preparation steps of the auxiliary resin are as follows: Add biphenol, phenolphthalein, 4,4'-difluorobenzophenone and sodium carbonate into a container, add sulfolane as a solvent and xylene as a water-carrying agent, introduce nitrogen, stir at 190-210°C for 2-3 hours, then heat to 220-230°C and stir for 2-3 hours, precipitate in a mixed solution of water and ethanol to obtain an auxiliary resin; The preparation steps of the sizing agent solution are as follows: Add biphenol, 2,6-dichlorobenzonitrile, 4,4'-difluorobenzophenone and potassium carbonate into a container, add N,N-dimethylpyrrolidone as a solvent and xylene as a water-carrying agent, introduce nitrogen, stir at 160°C to 170°C for 2 to 3 hours; then heat to 180°C to 185°C and stir for 2 to 3 hours, precipitate in a mixed solution of water and ethanol to obtain a sizing agent resin; The sizing agent resin is dissolved in N,N-dimethylpyrrolidone to prepare a sizing agent solution with a solid content of 0.5% to 10%.

2. The preparation method according to claim 1, characterized in that: The sized chopped carbon fibers are carbon fiber bundles with a length of 3 to 5 mm; the mass percentage of the sized chopped carbon fibers in S2 is 3% to 15%; the mass ratio of the phenolphthalein polyarylether nitrile ketone resin to the auxiliary resin is 8 to 5:2-5.

3. The preparation method according to claim 1, characterized in that: The solid content of the reaction system is 20% to 25%; the molar ratio of biphenol, phenolphthalein, 4,4'-difluorobenzophenone and sodium carbonate is 0.5 to 0.7: 0.3 to 0.5: 1.01 to 1.06: 1.5 to 2; and the volume ratio of xylene to cyclopentane sulfone is 1-3:

4.

4. The preparation method according to claim 1, characterized in that: The solid content of the reaction system is 20% to 25%; the molar ratio of biphenyl diphenol, 2,6-dichlorobenzonitrile, 4,4'-difluorobenzophenone and potassium carbonate is 1.01 to 1.05: 0.8 to 0.6: 0.2 to 0.4: 1.2 to 1.5; and the volume ratio of xylene to cyclopentane sulfone is 1 to 4:

6.

5. The preparation method according to claim 1, characterized in that: The volume ratio of water to ethanol in the mixed solution of water and ethanol is 5-7:3-5.

6. The preparation method according to claim 1, characterized in that: The structure of the phenolphthalein polyarylether nitrile ketone resin is as follows: m:n=8~5:2~5.

7. The preparation method according to claim 1 or 6, characterized in that: The reduced viscosity of phenolphthalein polyarylether nitrile ketone resin is 0.40-0.50, and the melt index of 5KG at 350°C is 1.8-3g / min.

8. The chopped carbon fiber reinforced blended modified phenolphthalein polyarylether nitrile ketone resin composite material prepared by the method according to any one of claims 1 to 7.

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