Preparation method of composite material frame based on in-situ polymerization

Abstract

The invention discloses a preparation method of a composite material frame based on in-situ polymerization, which comprises the following steps: modifying a resin matrix and a fiber reinforced material, pretreating graphene oxide powder added into caprolactam, adding the graphene oxide powder in the process, performing thermal reduction in the subsequent process, and synchronously performing the PA6 polymerization process. The PA6 is uniformly dispersed in a matrix, so that the polymerization reaction of the PA6 is facilitated, and the binding force of the matrix and an interface is also facilitated; znO (at) rGO is doped in the modified glass fiber, one of the ZnO (at) rGO can serve as a coupling agent for surface activation and can promote combination between a matrix and a reinforcement interface, and due to the existence of ZnO particles, the ultraviolet aging resistance of the composite material is enhanced, and expansion of microcracks of the material can be reduced. A synergistic enhancement effect is also achieved between the base body and the reinforcement body, and besides a mutual bridging and interlocking effect between functional groups, a micron-level mechanical interlocking effect is also achieved in the wrinkle morphology, so that the combination between the base body and the reinforcement body is firmer.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic module composite materials, and particularly relates to a preparation method and a preparation method of an in-situ polymerization composite material frame. Background Art

[0002] With the increasing improvement of people's environmental protection awareness and the implementation of policies restricting the emission of fossil energy combustion gases in many countries, renewable energy represented by solar power generation has developed rapidly. Especially in recent years, the rapid development of the photovoltaic industry in China has made solar power generation more and more well-known to the public.

[0003] The wide application of photovoltaic power generation technology not only significantly reduces the dependence on fossil fuels but also provides key technical support for achieving the global carbon neutrality goal. The importance of photovoltaic power generation is reflected in many aspects: (1) Photovoltaic power generation can greatly reduce greenhouse gas emissions; (2) The distributed characteristics of photovoltaic power generation enable it to reduce the dependence on centralized fossil fuel power generation systems and improve the security and flexibility of energy supply; (3) The photovoltaic industry has a significant promoting effect on economic development, driving the prosperity of photovoltaic manufacturing, installation and related upstream and downstream industries; (4) With the progress of photovoltaic technology and the improvement of the industrial chain, the levelized cost of electricity (LCOE) of photovoltaic power generation continues to decline. The IRENA report shows that the average levelized cost of electricity of global photovoltaic power generation projects has decreased by more than 80% cumulatively in the past decade, which makes photovoltaic power generation competitive with traditional fossil energy power generation methods and becomes one of the preferred options for newly built power installations globally. In China, the importance of photovoltaic power generation is particularly significant. As the world's largest photovoltaic manufacturing and application market, China occupies a dominant position in all links of the photovoltaic industrial chain.

[0004] In the cost composition of photovoltaic modules, the aluminum frame accounts for about 13%, which is the component with the highest cost proportion except for the battery. The technical route of the composite material frame is mainly to compound thermosetting resin (such as polyurethane) with glass fiber and prepare it through the pultrusion process. Limited by the reaction speed of thermosetting resin, the pultrusion production speed generally does not exceed 0.8 meters per minute. Using a composite material frame can reduce the cost per watt of the module by about 2 cents, save about 20 million yuan per GW, and it is expected that the entire photovoltaic module industry can save up to 10 billion yuan in costs. Therefore, promoting the composite material frame has important economic and social value.

[0005] To further improve the production efficiency of composite material frames and accelerate the industrialization and large-scale application and popularization speed of composite material frames, the present invention proposes a preparation method for composite material frames based on in-situ polymerization. Specifically, caprolactam is used to impregnate glass fibers, and PA6 / glass fiber composite materials are produced by in-situ polymerization in a mold. Through the continuous traction of a pultrusion machine, the polymerization reaction continuously proceeds in the mold, realizing the batch preparation of composite material frames. The preparation method of the present invention can enable the production speed of composite material frames to reach (3 - 10) meters per minute. Moreover, since the synthesized product PA6 of caprolactam has thermoplasticity, the prepared composite material frames can be recycled and crushed into glass fiber-reinforced plastic particles for reuse. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a preparation method for composite material frames based on in-situ polymerization.

[0007] To achieve the above purpose, the present invention proposes the following technical solutions:

[0008] A preparation method for composite material frames based on in-situ polymerization, wherein the composite material frames are cut from glass fiber-reinforced nylon 6 composite materials. The characteristics of the preparation method include the following steps:

[0009] 1) Store the pretreated caprolactam after water removal and caprolactam in storage tanks A and B respectively; add the pretreated caprolactam and the catalyst sodium caprolactam to transfer tank A in proportion and mix evenly in transfer tank A. Add caprolactam and the initiator bisacylated lactam - 1,6 - hexanediamine to transfer tank B and mix evenly in transfer tank B. Add the mixtures in transfer tanks A and B to a twin-screw extruder at a mass ratio of 1:(1 - 1.2) at the same flow rate, and uniformly mix and extrude the mixed melt into a composite mold through the twin-screw extruder;

[0010] The composite mold includes an impregnation section, a reaction section, and a cooling section, and a heat insulation layer is provided between the impregnation section and the reaction section; the mixed melt enters the impregnation section of the composite mold from the twin-screw extruder;

[0011] 2) Traction the modified glass fibers into the impregnation section of the composite mold and impregnate them in the mixed melt;

[0012] 3) Heat the modified glass fibers treated in step 2) to initiate the in-situ polymerization reaction of caprolactam adsorbed on the modified glass fibers, and then obtain the glass fiber-reinforced nylon 6 composite materials through rolling and cooling.

[0013] (4) Under the action of the traction mechanism, the modified glass fiber-reinforced nylon 6 composite material is continuously pulled out from the composite mold, cut into the required length, collected and packaged, and finally assembled to obtain the composite material frame;

[0014] Among them, the preparation method of the modified glass fiber includes the following steps:

[0015] (1) Ultrasonic impurity removal

[0016] Place the glass fiber in acetone and ultrasonicate for 30 min, then immerse it for 4 - 6 h, and then wash it with deionized water;

[0017] (2) Surface activation

[0018] Immerse the glass fiber after ultrasonic impurity removal in step (1) above in the active impregnating solution for 6 - 8 h, then perform two dips and two rolls, and then dry it at 100 °C to obtain the modified glass fiber; among them, the active impregnating solution is uniformly mixed by deionized water, absolute ethanol, and ZnO@rGO in a mass ratio of 85:9:6.

[0019] On the basis of the above solution and as a preferred solution of the above solution, the composition of caprolactam and sodium caprolactamate in step 1) is pretreated, where the molar concentration of sodium caprolactamate is 1% - 3%; the composition of caprolactam and bisacylated lactam - 1,6 - hexanediamine in step 1), where the molar concentration of bisacylated lactam - 1,6 - hexanediamine is 1% - 2.5%.

[0020] On the basis of the above solution and as a preferred solution of the above solution, the pretreatment of caprolactam includes the following treatment steps:

[0021] Add caprolactam and deionized water to the reaction kettle at a mass ratio of 100:30, stir evenly at a speed of 200 - 500 rpm, and then add 0.5 - 1.5 parts of graphene oxide powder based on the weight of caprolactam. After stirring for 15 - 20 min, evacuate for 15 min and introduce nitrogen for 15 min in turn, and cycle at least three times; heat up to 80 °C and continue stirring until the substances in the reaction kettle are completely melted. After stabilizing for 15 min, heat up to 200 °C, evacuate for 15 min and introduce nitrogen for 15 min again, and continue stirring for 6 - 8 h; after the reaction kettle system returns to normal pressure, open the reaction kettle, take out the mixture, cool it, dry it, cut it into pieces, and pulverize it to obtain the pretreated caprolactam.

[0022] On the basis of the above solution and as a preferred solution of the above solution, the graphene oxide powder is obtained by drying the graphene oxide solution, followed by grinding and screening, and its screening size is 3 um - 53 um.

[0023] Based on the above - mentioned solution and as a preferred solution of the above - mentioned solution, the glass fiber is an alkali - free glass fiber with a linear density of 4800 Tex.

[0024] Based on the above - mentioned solution and as a preferred solution of the above - mentioned solution, the temperatures of storage tank A and storage tank B are maintained at 110°C - 120°C, and the temperatures of transition tank A and transition tank B are maintained at 80°C - 100°C.

[0025] Based on the above - mentioned solution and as a preferred solution of the above - mentioned solution, the length of the impregnation section of the composite die is 200 mm - 400 mm; the length of the reaction section is 500 mm - 1000 mm; the length of the cooling section is 300 mm - 500 mm.

[0026] Based on the above - mentioned solution and as a preferred solution of the above - mentioned solution, the temperature of the impregnation section is 80°C - 110°C; the temperature of the reaction section is 200°C - 260°C.

[0027] Compared with the prior art, the technical solution of the present invention has obtained the following beneficial effects:

[0028] The present invention discloses a preparation method of an in - situ polymerization composite material frame, including the modification operations of the resin matrix and the fiber - reinforced material, pre - treating the graphene oxide powder added to caprolactam, adding the graphene oxide powder during the process, and performing thermal reduction in the subsequent process, and the PA6 polymerization process is carried out synchronously and is evenly dispersed in the matrix, which not only helps the polymerization reaction of PA6 but also helps the interfacial bonding force between the matrix and the interface; ZnO@rGO is doped in the modified glass fiber, which can act as a coupling agent for surface activation and can also promote the bonding between the matrix and the interface of the reinforcing body. Due to the presence of ZnO particles, the anti - ultraviolet aging performance of the composite material is enhanced, and the expansion of material micro - cracks can also be reduced. There is also a synergistic strengthening effect between the two. In addition to the mutual bridging and interlocking effect between functional groups, there is also a micron - level mechanical interlocking effect in the wrinkled morphology, making the bonding between the matrix and the reinforcing body more firm.

[0029] It should be understood that all combinations of the foregoing concepts and additional concepts described in more detail below can be regarded as part of the disclosure of the subject matter of the present invention as long as such concepts do not contradict each other.

[0030] The foregoing and other aspects, embodiments, and features of the teachings of the present invention can be more fully understood from the following description. Other additional aspects of the present invention, such as the features and / or beneficial effects of the exemplary embodiments, will be apparent in the following description or will be learned through the practice of the specific embodiments according to the teachings of the present invention. Brief Description of the Drawings

[0031] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, wherein:

[0032] Figure 1 is the process flow chart of the present invention;

[0033] Figure 2 is the schematic diagram of the composite mold of the present invention;

[0034] Figure 3 is the scanning electron microscope image of the materials of the present invention: (a) ZnO@rGO; (b) modified glass fiber;

[0035] Figure 4 is the scanning electron microscope image of the materials of the present invention: (a) SEM cross-sectional morphology of the composite material of Comparative Example 3; (b) SEM cross-sectional morphology of the composite material of Comparative Example 4; (c) SEM cross-sectional morphology of the composite material of Comparative Example 5; (d) SEM cross-sectional morphology of the composite material of Example 1. Detailed Embodiments

[0036] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein shall have the ordinary meanings as understood by those of ordinary skill in the art to which the present invention pertains.

[0037] The "first", "second" and similar terms used in the specification and claims of this patent application of the present invention do not denote any order, quantity or importance, but are only used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "a", "an" or "the" and similar terms do not denote a limitation of quantity, but mean that there is at least one. The terms such as "including" or "comprising" mean that the elements or objects appearing before "including" or "comprising" cover the features, wholes, steps, operations, elements and / or components listed after "including" or "comprising", and do not exclude the existence or addition of one or more other features, wholes, steps, operations, elements, components and / or their combinations. The terms such as "upper", "lower", "left" and "right" are only used to represent relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0038] In the present invention, commercially available caprolactam is selected for water treatment and stored in a storage tank. In the preparation process of the present invention, the storage tank used can store raw materials for a long time and has functions such as waterproof, moisture-proof and heat preservation to ensure the quality and stability of the raw materials. The storage tank needs to be moisture-proof and dehumidified, so its temperature is above the boiling point of water; for the transition tank, it only needs to be maintained above the melting point of the components, so that the reaction in the mixing tank is as slow as possible, and then it is reheated in the mold for rapid reaction.

[0039] Further, the pretreated caprolactam includes graphene oxide powder. During the preparation of the pretreated caprolactam, three main reactions occur: one is the hydrolysis polymerization of PA6. Under the control of nitrogen atmosphere and vacuum degree, part of the caprolactam undergoes hydrolysis polymerization to form a PA6 prepolymer, which is uniformly mixed with caprolactam in a molten state; the second is the thermal reduction of graphene oxide. In this system, the graphene oxide powder is uniformly dispersed in the molten mixture of caprolactam by stirring. After the temperature exceeds 120 °C, the graphene oxide undergoes a thermal reduction reaction to form a monolayer structure with good transparency and typical wrinkled morphology; the third is that during the synchronous process of the two parts of the reaction, a PA6 composite material in-situ polymerized with graphene oxide powder occurs. The reason for such operation is that the cost of graphene oxide powder with a multi-layer structure is much lower than that of single-layer graphene oxide and single-layer graphene. Moreover, in the in-situ polymerization reaction, small molecule structures in the system can react between the graphene oxide sheets, and there is also a certain intercalation and exfoliation effect. Preferably, calculated by weight parts of caprolactam, the added graphene oxide powder is 0.5 - 3.5 parts.

[0040] In the prior art, acetone solution is mostly used for ultrasonic treatment, soaking, washing, etc. of fibers. One is to remove the sizing agent on the surface of glass fibers, and deionized water is used to wash the glass fibers. The other is to remove the residues on the surface of glass fibers. The active impregnating solution in the preparation process of the modified glass fibers of the present invention is uniformly mixed by deionized water, absolute ethanol, and ZnO@rGO in a mass ratio of 85:9:6.

[0041] The preparation method of the ZnO@rGO is as follows:

[0042] Take graphene oxide (GO) from Nanjing Xianfeng Nano Material Technology Co., Ltd., configure it into an alcohol solution of 0.2 mg / mL, after ultrasonic treatment, stir at a speed of 500 - 700 r / min, and drop APTES according to 1% of the volume of the graphene oxide alcohol solution, and stir for 30 min at the same stirring speed to obtain a mixed liquid A.

[0043] Secondly, prepare a homogeneous solution of zinc acetate in dimethyl sulfoxide with a concentration of 2 mol / L. At the same time, prepare a sodium hydroxide ethanol solution with the same concentration. Then, dropwise add the homogeneous solution of zinc acetate in dimethyl sulfoxide into the mixed liquid A at a dropping rate of 1.5 mL / min, stir evenly at the same stirring speed, and maintain for 30 min to obtain the mixed liquid B. Then, dropwise add the sodium hydroxide ethanol solution into the mixed liquid B. After the dropping is completed, stir at a stirring speed of 700 - 900 r / min for 1 h. Finally, place the mixed solution in a reaction kettle, react at 100 °C for 2 h, and then cool naturally. Wash the product with ethanol, let it stand, and wash it repeatedly with deionized water 3 - 5 times to obtain the ZnO@rGO aqueous solution. Then, calculate the solid content of this batch of products and label them. Among them, the mass ratio of zinc acetate to sodium hydroxide used is 11:5.

[0044] During the preparation of ZnO@rGO, GO has a large specific surface area, and its surface is rich in functional groups such as carboxyl, hydroxyl, and epoxy groups. Coupled with its unique wrinkled morphology, it provides binding sites for the growth of ZnO particles. When directly using the dimethyl sulfoxide solution of zinc acetate and the sodium hydroxide ethanol solution to prepare nano-ZnO particles, due to the lack of matrix attachments, and when the zinc source in the solution system is excessive, due to the electrostatic attraction of Zn 2+ , the ZnO particles grow and continuously aggregate while growing. GO, as the growth site of ZnO particles, can reduce the possibility of particle aggregation. In addition, in the system, APTES can chemically bond with the surface of zinc oxide particles to form a stable encapsulation layer, improving its dispersibility and stability in GO; the aminopropyl functional group of APTES can introduce other functional groups or functional groups to regulate the surface properties of ZnO particles. Further, after the uniformly stirred solution is subjected to a hydrothermal reaction kettle reaction, GO is partially reduced, and the obtained ZnO@rGO has more stable properties and does not affect the stable structure of hydrogen bonds formed between the functional groups in the subsequent system and the surface of the modified glass fiber. The morphology and structure of ZnO@rGO can be observed by scanning electron microscopy, and the results are as Figure 3 (a) shown.

[0045] The active impregnating solution is composed of deionized water, absolute ethanol, and ZnO@rGO mixed according to a mass ratio of 85:9:6. According to the preparation method of ZnO@rGO, not only GO with high surface activity and capable of bridging exists in this active impregnating solution, but also active functional groups of APTES exist in this system. In an aqueous solution, APTES that has not participated in the ZnO@rGO reaction can be hydrolyzed into small molecular structures with hydroxyl and amino groups. The surface of the glass fiber is smooth and has many hydroxyl groups. The surface of the glass fiber after being treated with the active impregnating solution is as Figure 3 (b) shown, and the morphological changes on the surface of the glass fiber can be clearly observed.

[0046] Example 1

[0047] A preparation method of a composite material frame based on in-situ polymerization, wherein the composite material frame is cut from a glass fiber reinforced nylon 6 composite material. The preparation method includes the following steps:

[0048] 1) Store the pre-treated caprolactam after water removal and caprolactam in storage tanks A and B respectively;

[0049] Add the pre-treated caprolactam and the catalyst sodium caprolactam to transfer tank A in proportion and mix evenly in transfer tank A. Add caprolactam and the initiator bis-acylated lactam-1,6-hexanediamine to transfer tank B and mix evenly in transfer tank B. Add the mixtures in transfer tanks A and B to the twin-screw extruder at a mass ratio of 1:1.05 and the same flow rate, and uniformly mix and extrude the mixed melt into a composite die through the twin-screw extruder;

[0050] The composite die includes an impregnation section, a reaction section, and a cooling section, and a heat insulation layer is provided between the impregnation section and the reaction section; the mixed melt enters the impregnation section of the composite die from the twin-screw extruder;

[0051] 2) Pull the modified glass fiber into the impregnation section of the composite die and impregnate it in the mixed melt;

[0052] 3) Heat the modified glass fiber processed in step 2) to initiate the in-situ polymerization reaction of caprolactam adsorbed on the modified glass fiber, and then roll and cool it to obtain the glass fiber reinforced nylon 6 composite material;

[0053] 4) Continuously pull out the modified glass fiber reinforced nylon 6 composite material from the composite die under the action of a traction mechanism, cut it into the required length, collect and package it, and finally assemble it to obtain the composite material frame;

[0054] Among them, the preparation method of the modified glass fiber includes the following steps:

[0055] (1) Ultrasonic impurity removal

[0056] Place the glass fiber in acetone and ultrasonicate for 30 min, then impregnate for 4 h, and then wash with deionized water;

[0057] (2) Surface activation

[0058] Immerse the glass fiber after ultrasonic impurity removal in step (1) in the active impregnating solution for 6 h, then perform two dips and two rolls, and then dry at 100 °C to obtain the modified glass fiber; among them, the active impregnating solution is uniformly mixed by deionized water, anhydrous ethanol, and ZnO@rGO in a mass ratio of 85:9:6.

[0059] Further, the pre-treated caprolactam includes the following treatment steps:

[0060] Add caprolactam and deionized water into the reaction kettle at a mass ratio of 100:30, stir evenly at a speed of 200 - 500 rpm. Based on the weight parts of caprolactam, then add 0.5 part of graphene oxide powder. After stirring for 15 min, evacuate for 15 min and then introduce nitrogen for 15 min, and repeat the cycle at least three times; heat up to 80 °C and continue stirring until the substances in the reaction kettle are completely melted. After stabilizing for 15 min, heat up to 200 °C, evacuate for 15 min again, introduce nitrogen for 15 min, and continue stirring for 7 h; after the reaction, restore the pressure in the reaction kettle system to normal pressure. Open the reaction kettle, take out the mixture, cool it, dry it, cut it into pieces, and pulverize it to obtain the pre-treated caprolactam.

[0061] Further, the size of the graphene oxide powder is 3 μm.

[0062] Further, the glass fiber is an E-glass fiber with a linear density of 4800 Tex.

[0063] Further, the temperatures of the storage tank A and the storage tank B are maintained at 110 °C, and the temperatures of the transition tank A and the transition tank B are maintained at 80 °C.

[0064] Further, the parameters of the composite mold in this embodiment are: the impregnation section length is 300 mm, and the temperature is 100 °C; the reaction section length is 900 mm, and the temperature is 250 °C; the cooling section length is 500 mm, and the temperature is 40 °C.

[0065] Still further, in the composition of the pre-treated caprolactam and sodium caprolactamate in step 1), the molar concentration of sodium caprolactamate is 2%; in the composition of caprolactam and bisacylated lactam - 1,6 - hexanediamine in step 1), the molar concentration of bisacylated lactam - 1,6 - hexanediamine is 2.5%.

[0066] In summary, in this embodiment, 50 parts of pre-treated caprolactam and 50 parts of caprolactam are weighed. The usage amount of the catalyst sodium caprolactamate is 1 part, and the usage amount of bisacylated lactam - 1,6 - hexanediamine is 1.25 parts. In the prepared glass fiber reinforced nylon 6 composite material, according to the test method of resin content in GB / T 2577 - 2005 "Test Method for Resin Content of Glass Fiber Reinforced Plastics", the resin content is tested, and then the weight content of the glass fiber is obtained as 60%.

[0067] Example 2

[0068] Different from the above-mentioned Embodiment 1, a preparation method of a composite material frame based on in-situ polymerization, the composite material frame is cut from a glass fiber-reinforced nylon 6 composite material, and the preparation method includes the following steps:

[0069] 1) Store the pretreated caprolactam and caprolactam after water removal in storage tanks A and B respectively;

[0070] Add the pretreated caprolactam and caprolactam sodium catalyst to transfer tank A in proportion and mix evenly in transfer tank A. Add caprolactam and initiator bis-acylated lactam-1,6-hexanediamine to transfer tank B and mix evenly in transfer tank B. Add the mixtures in transfer tanks A and B to the twin-screw extruder at a mass ratio of 1:1 and the same flow rate, and uniformly mix and extrude the mixed melt into the composite mold through the twin-screw extruder;

[0071] The composite mold includes an impregnation section, a reaction section, and a cooling section, and a heat insulation layer is provided between the impregnation section and the reaction section; the mixed melt enters the impregnation section of the composite mold from the twin-screw extruder;

[0072] 2) Draw the modified glass fiber into the impregnation section of the composite mold and impregnate it in the mixed melt;

[0073] 3) Heat the modified glass fiber treated in step 2) to initiate the in-situ polymerization reaction of caprolactam adsorbed on the glass fiber, and then roll and cool to obtain the glass fiber-reinforced nylon 6 composite material;

[0074] 4) Continuously draw out the glass fiber-reinforced nylon 6 composite material from the composite mold under the action of the traction mechanism, cut it into the required length, collect and package it, and finally assemble to obtain the composite material frame;

[0075] Among them, the fiber-reinforced material is modified glass fiber, and the preparation method of the modified glass fiber includes the following steps:

[0076] (1) Ultrasonic impurity removal

[0077] Place the glass fiber in acetone and ultrasonicate for 30 min, then impregnate for 4 h, and then wash with deionized water;

[0078] (2) Surface activation

[0079] Immerse the glass fiber after ultrasonic impurity removal in step (1) in the active impregnating solution for 6 h, then perform two dips and two rolls, and then dry at 100 °C to obtain the modified glass fiber; among them, the active impregnating solution is uniformly mixed by deionized water, absolute ethanol, and ZnO@rGO in a mass ratio of 85:9:6.

[0080] Further, in step 1), the composition of caprolactam and sodium caprolactamate is pretreated, wherein the molar concentration of sodium caprolactamate is 1%; in step 1), the composition of caprolactam and bisacylated lactam-1,6-hexanediamine, wherein the molar concentration of bisacylated lactam-1,6-hexanediamine is 1%.

[0081] Further, the pretreatment of caprolactam includes the following treatment steps:

[0082] Caprolactam and deionized water are added to the reaction kettle in a mass ratio of 100:30, stirred evenly at a speed of 200 rpm. Based on the weight parts of caprolactam, 0.5 part of graphene oxide powder is then added. After stirring for 20 min, vacuum is pumped for 15 min and nitrogen is introduced for 15 min, and this cycle is repeated at least three times; the temperature is raised to 80 °C and stirring continues until the substances in the reaction kettle are completely melted. After stabilizing for 15 min, the temperature is raised to 200 °C, vacuum is pumped again for 15 min and nitrogen is introduced for 15 min, and stirring continues for 8 h; after the reaction, the pressure in the reaction kettle system returns to normal pressure. After opening the reaction kettle, the mixture is taken out, cooled, dried, cut into pieces, and pulverized to obtain pretreated caprolactam.

[0083] Further, the graphene oxide powder is formed by drying the graphene oxide solution, followed by grinding and screening, and its screening size is 33 um.

[0084] Further, the glass fiber is an alkali-free glass fiber with a linear density of 1200 Tex.

[0085] Further, the temperatures of storage tank A and storage tank B are maintained at 110 °C, and the temperatures of transition tank A and transition tank B are maintained at 80 °C.

[0086] In summary, in this example, 50 parts of pretreated caprolactam and 50 parts of caprolactam are weighed. The usage amount of the catalyst sodium caprolactamate is 0.5 part, and the usage amount of bisacylated lactam-1,6-hexanediamine is 0.5 part. Similarly, in the prepared glass fiber reinforced nylon 6 composite material, the weight content of glass fiber is 63%.

[0087] Example 3

[0088] Different from the above Example 1, a preparation method of an in-situ polymerization composite material frame, the composite material frame is cut from a glass fiber reinforced nylon 6 composite material, and this preparation method includes the following steps:

[0089] 1) Store the dehydrated pretreated caprolactam and caprolactam in storage tank A and storage tank B respectively;

[0090] Pre-treated caprolactam and sodium caprolactamate catalyst are added to transition tank A in proportion and mixed evenly therein. Caprolactam and the initiator bisacylated lactam - 1,6 - hexanediamine are added to transition tank B and mixed evenly therein. The mixtures in transition tank A and transition tank B are added to a twin - screw extruder at the same flow rate according to a mass ratio of 1:1, and are evenly mixed by the twin - screw extruder and extruded into a composite die as a mixed melt;

[0091] The composite die includes an impregnation section, a reaction section, and a cooling section. A heat - insulating layer is provided between the impregnation section and the reaction section; The mixed melt enters the impregnation section of the composite die from the twin - screw extruder;

[0092] 2) Traction - modified glass fiber enters the impregnation section of the composite die and is impregnated in the mixed melt;

[0093] 3) Heat the modified glass fiber processed in step 2) to initiate an in - situ polymerization reaction of caprolactam adsorbed on the glass fiber, and then through rolling and cooling, the glass fiber reinforced nylon 6 composite material is obtained;

[0094] 4) Under the action of a traction mechanism, the glass fiber reinforced nylon 6 composite material is continuously pulled out from the composite die, cut into required lengths and collected and packaged, and finally assembled to obtain the composite material frame;

[0095] Among them, the fiber - reinforced material is modified glass fiber, and the preparation method of the modified glass fiber includes the following steps:

[0096] (1) Ultrasonic impurity removal

[0097] The glass fiber is placed in acetone and ultrasonicated for 30 min, then impregnated for 6 h, and then washed with deionized water;

[0098] (2) Surface activation

[0099] The glass fiber after ultrasonic impurity removal in the above step (1) is immersed in an active impregnating solution for 8 h, then subjected to two - dip and two - roll, and then dried at 100 °C to obtain the modified glass fiber; Among them, the active impregnating solution is uniformly mixed by deionized water, absolute ethanol, and ZnO@rGO according to a mass ratio of 85:9:6.

[0100] Furthermore, in step 1), the composition of pre - treated caprolactam and sodium caprolactamate, where the molar concentration of sodium caprolactamate is 3%; In step 1), the composition of caprolactam and bisacylated lactam - 1,6 - hexanediamine, where the molar concentration of bisacylated lactam - 1,6 - hexanediamine is 2.5%.

[0101] Furthermore, the pre - treated caprolactam includes the following treatment steps:

[0102] Caprolactam and deionized water were added to the reaction kettle in a mass ratio of 100:30, and stirred evenly at a speed of 500 rpm. Based on the weight parts of caprolactam, 1.5 parts of graphene oxide powder were then added. After stirring for 15 min, vacuum was pumped for 15 min and nitrogen was introduced for 15 min, and this cycle was repeated at least three times. The temperature was raised to 80 °C and stirring continued until the substances in the reaction kettle were completely melted. After stabilizing for 15 min, the temperature was raised to 200 °C, and vacuum was pumped again for 15 min and nitrogen was introduced for 15 min, and stirring continued for 7 h. After the reaction, the pressure of the reaction kettle system returned to normal pressure. After opening the reaction kettle, the mixture was taken out, cooled, dried, cut into pieces, and pulverized to obtain pretreated caprolactam.

[0103] Further, the graphene oxide powder was obtained by drying the graphene oxide solution, followed by grinding and screening, and its screening size was 53 μm.

[0104] Further, the glass fiber was an alkali-free glass fiber with a linear density of 9600 Tex.

[0105] Further, the temperatures of storage tank A and storage tank B were maintained at 120 °C, and the temperatures of transfer tank A and transfer tank B were maintained at 100 °C.

[0106] In summary, in this example, 50 parts of pretreated caprolactam and 50 parts of caprolactam were weighed. The usage amount of the catalyst sodium caprolactam was 1.5 parts, and the usage amount of bisacylated lactam-1,6-hexanediamine was 0.5 parts. Similarly, in the prepared glass fiber reinforced nylon 6 composite material, the weight content of the glass fiber was 62%.

[0107] Comparative Example 1

[0108] Different from Example 1 above, caprolactam and the catalyst sodium caprolactam were added to transfer tank A and mixed evenly therein; caprolactam and the initiator bisacylated lactam-1,6-hexanediamine were added to transfer tank B and mixed evenly therein. The mixtures in transfer tank A and transfer tank B were added to the twin-screw extruder at the same flow rate, and evenly mixed by the twin-screw extruder and the mixed melt was extruded into the injection molding machine. The parameters were set according to the temperatures and pressures of the reaction section and the cooling section of the composite mold, and a test standard sample was obtained after cooling and molding.

[0109] Other processes and parameters refer to Example 1.

[0110] Comparative Example 2

[0111] Different from the above-mentioned Example 1, the pretreated caprolactam and the catalyst sodium caprolactam are added to the transition tank A in proportion and mixed evenly in the transition tank A; caprolactam and the initiator bisacylated lactam-1,6-hexanediamine are added to the transition tank B and mixed evenly in the transition tank B. The mixtures in the transition tank A and the transition tank B are added to the twin-screw extruder at the same flow rate, and are evenly mixed by the twin-screw extruder and extruded into a mixed melt into the injection molding machine. The parameters are set according to the temperature and pressure of the reaction section and the cooling section of the composite mold, and a test standard sample is obtained after cooling and forming.

[0112] For other processes and parameters, refer to Example 1.

[0113] Comparative Example 3

[0114] Different from the above-mentioned Example 1, a preparation method of an in-situ polymerization composite material frame, the composite material frame is cut from a glass fiber reinforced nylon 6 composite material, and the preparation method includes the following steps:

[0115] 1) The dehydrated caprolactam is stored in the storage tank A and the storage tank B respectively;

[0116] Caprolactam and the catalyst sodium caprolactam are added to the transition tank A in proportion and mixed evenly in the transition tank A. Caprolactam and the initiator bisacylated lactam-1,6-hexanediamine are added to the transition tank B and mixed evenly in the transition tank B. The mixtures in the transition tank A and the transition tank B are added to the twin-screw extruder at the same flow rate according to the mass ratio of 1:1, and are evenly mixed by the twin-screw extruder and extruded into a mixed melt into the composite mold;

[0117] The composite mold includes an impregnation section, a reaction section, and a cooling section, and a heat insulation layer is provided between the impregnation section and the reaction section; the mixed melt goes from the twin-screw extruder to the impregnation section of the composite mold;

[0118] 2) Pull the glass fiber into the impregnation section of the composite mold and impregnate it in the mixed melt;

[0119] 3) Heat the glass fiber treated in step 2) to initiate the in-situ polymerization reaction of caprolactam adsorbed on the glass fiber, and then roll and cool to obtain the glass fiber reinforced nylon 6 composite material;

[0120] 4) Under the action of the traction mechanism, continuously pull out the glass fiber reinforced nylon 6 composite material from the composite mold, cut it into the required length and collect and package it, and finally assemble it to obtain the composite material frame;

[0121] For other processes and parameters, refer to Example 1. Similarly, in the prepared glass fiber reinforced nylon 6 composite material, the weight content of the glass fiber is 60%.

[0122] Comparative Example 4

[0123] Different from the above-mentioned Example 1, a preparation method of a composite material frame based on in-situ polymerization, the composite material frame is cut from a glass fiber reinforced nylon 6 composite material, and this preparation method includes the following steps:

[0124] 1) Store the dehydrated pre-treated caprolactam and caprolactam in storage tanks A and B respectively;

[0125] Add the pre-treated caprolactam and the catalyst sodium caprolactam to transfer tank A in proportion and mix evenly in transfer tank A. Add caprolactam and the initiator bis-acylated lactam-1,6-hexanediamine to transfer tank B and mix evenly in transfer tank B. Add the mixtures in transfer tanks A and B to the twin-screw extruder at a mass ratio of 1:1 and the same flow rate, and uniformly mix and extrude the mixed melt into the composite die through the twin-screw extruder;

[0126] The composite die includes an impregnation section, a reaction section, and a cooling section, and a heat insulation layer is provided between the impregnation section and the reaction section; the mixed melt enters the impregnation section of the composite die from the twin-screw extruder;

[0127] 2) Draw glass fiber into the impregnation section of the composite die and impregnate it in the mixed melt;

[0128] 3) Heat the glass fiber processed in step 2) to initiate the in-situ polymerization reaction of caprolactam adsorbed on the glass fiber, and then through rolling and cooling, the glass fiber reinforced nylon 6 composite material is obtained;

[0129] 4) Continuously pull out the glass fiber reinforced nylon 6 composite material from the composite die under the action of the traction mechanism, cut it into the required length, collect and package it, and finally assemble it to obtain the composite material frame;

[0130] Other processes and parameters refer to Example 1. Similarly, in the prepared glass fiber reinforced nylon 6 composite material, the weight content of the glass fiber is 60%.

[0131] Comparative Example 5

[0132] Different from the above-mentioned Example 1, a preparation method of a composite material frame based on in-situ polymerization, the composite material frame is cut from a glass fiber reinforced nylon 6 composite material, and this preparation method includes the following steps:

[0133] 1) Store the dehydrated pre-treated caprolactam and caprolactam in storage tanks A and B respectively;

[0134] Pre-treated caprolactam and sodium caprolactamate as a catalyst are added to transition tank A in proportion and mixed evenly therein. Caprolactam and bisacylated lactam-1,6-hexanediamine as an initiator are added to transition tank B and mixed evenly therein. The mixtures in transition tank A and transition tank B are added to a twin-screw extruder at the same flow rate according to a mass ratio of 1:1, and are evenly mixed by the twin-screw extruder and extruded into a composite die as a mixed melt;

[0135] The composite die includes an impregnation section, a reaction section, and a cooling section, and a heat insulation layer is provided between the impregnation section and the reaction section; the mixed melt enters the impregnation section of the composite die from the twin-screw extruder;

[0136] 2) Traction-modified glass fibers are introduced into the impregnation section of the composite die and impregnated in the mixed melt;

[0137] 3) The modified glass fibers processed in step 2) are heated to initiate an in-situ polymerization reaction of caprolactam adsorbed on the modified glass fibers, and then are roll-pressed and cooled to obtain the glass fiber reinforced nylon 6 composite material;

[0138] 4) Under the action of a traction mechanism, the glass fiber reinforced nylon 6 composite material is continuously pulled out from the composite die, cut into required lengths, collected and packaged, and finally assembled to obtain the composite material frame;

[0139] Among them, the preparation method of the modified glass fibers includes the following steps:

[0140] (1) Ultrasonic impurity removal

[0141] The glass fibers are placed in acetone and ultrasonicated for 30 min, then impregnated for 4 h, and then washed with deionized water;

[0142] (2) Surface activation

[0143] The glass fibers after ultrasonic impurity removal in the above step (1) are immersed in an active impregnating solution for 6 h, then subjected to two-dip and two-roll, and then dried at 100 °C to obtain the modified glass fibers; among them, the active impregnating solution is uniformly mixed by deionized water, absolute ethanol, and KH550 according to a mass ratio of 85:9:6.

[0144] Other processes and parameters refer to Example 1. Similarly, in the prepared glass fiber reinforced nylon 6 composite material, the weight content of the glass fibers is 60%.

[0145] Performance testing

[0146] 1. Mechanical property testing

[0147] According to the national standard GB / T1447-2005, the tensile properties of the samples were tested using the Instron 5982 universal material testing system (USA). The samples should be dumbbell-shaped, with a sample size of 180 mm × 10 mm, and stretched at a rate of 2 mm / min.

[0148] According to the national standard GB / T1451-2005, the samples were impact tested and the relevant mechanical properties were tested using the ZBC-1151-1 impact testing machine (Shenzhen Xinsansi Material Testing Co., Ltd.). The unnotched impact strength test was performed using a 120 mm × 10 mm sample.

[0149] Each of the above samples shall be tested in at least 5 groups.

[0150] 2. Deformation temperature

[0151] According to the IOS 75 standard, the deformation temperature test of the composite material was carried out at 1.8 MPa.

[0152] 3. Water absorption and molding shrinkage

[0153] In order to ensure the normal use of composite materials, the water absorption of the materials is also one of the reference standards. For this reason, we tested the water absorption rate of the materials according to the IOS 62 standard. At the same time, in order to test the molding stability of composite materials, the test samples were prepared according to the standard requirements, and the molding shrinkage of the materials was tested according to the IOS 294 standard.

[0154] 4. Corrosion resistance

[0155] In order to ensure that the composite materials are more suitable for use in photovoltaic modules, we also tested their corrosion resistance. According to ASTM D543-95 "Standard Test Method for Resistance of Plastics to Chemical Reagents", we conducted Practice A test, immersed the samples in a chemical medium of specified concentration, photographed the sample morphology before and after immersion, and observed whether its physical appearance changed.

[0156] 5. Anti-ultraviolet aging performance

[0157] In order to ensure that the composite material has anti-ultraviolet aging properties, we placed the material under ultraviolet light for 800 hours and then conducted mechanical property tests.

[0158] According to the above test standards and requirements, test samples of Examples 1-3 and Comparative Examples 1-5 were prepared, and then relevant performance tests were performed. The test comparison results are shown in Table 1.

[0159] Table 1 Performance test comparison results

[0160] As can be seen from the test data in Table 1, the mechanical properties of the PA6 resin obtained by direct polymerization of caprolactam using the present invention are poor. This is mainly because in the initial stage of hydrolysis polymerization of PA6, the more water there is, the more favorable it is for the ring-opening reaction of caprolactam. However, in the later stage, the more water there is, the lower the molecular weight of the product. After adding graphene oxide powder, there is competition between caprolactam and graphene oxide powder in the system. Under the condition of fixed water content, caprolactam can only satisfy partial polymerization at the same time and temperature; moreover, in the later stage, the water generated by the pre-polymerization of PA6 is discharged out of the system due to the rise in temperature, vacuum pumping, and nitrogen atmosphere. Therefore, the polymer prepared by pretreating caprolactam has more excellent mechanical properties than the PA6 resin obtained by direct polymerization of caprolactam.

[0161] In Comparative Example 3, due to the addition of glass fiber reinforcements, during the testing process of the composite material, the stress is transferred from the matrix resin to the high-strength glass fibers, thereby increasing its mechanical properties. However, due to the smooth surface of the untreated glass fibers, the interfacial bonding with the matrix is poor, as shown in Figure 4 (a), which affects the further development and use of the material. Therefore, we carried out surface modification on both the matrix and the glass fiber reinforcements respectively. In Comparative Example 4, as can be observed from the scanning electron microscope results, the use of pretreated caprolactam improved the interfacial bonding between the matrix and the reinforcements, but there was still fiber pull-out between the glass fibers and the matrix, as shown in Figure 4 (b). In the prior art, silane coupling agents are mostly used for fiber surface treatment. On this basis, combined with our matrix modification, in Comparative Example 5, we prepared an in-situ polymerization composite material with KH550 coupling agent-modified glass fibers, and its mechanical properties increased slightly. From the perspective of interfacial bonding analysis, the interface between the two was significantly improved, as shown in Figure 4 (c). However, the degree of improvement is not as excellent as that of the composite material prepared by the preparation method of the present invention, as shown in Figure 4 (d). Further, in the modified glass fibers of the present invention, the modified glass fibers are obtained by impregnation treatment with the active impregnating solution, and the active impregnating solution is uniformly mixed by deionized water, absolute ethanol, and ZnO@rGO in a mass ratio of 85:9:6. The treatment principle of the active impregnating solution on the glass fibers is similar to that of the silane coupling agent, both of which can activate the glass fiber surface and promote the interfacial bonding force between the matrix and the reinforcements; further, due to the presence of ZnO particles in ZnO@rGO, the anti-ultraviolet aging performance of the composite material is enhanced, and the ZnO particles are evenly dispersed on the surface of GO.

[0162] In summary, compared with PA6 and glass fiber reinforced PA6 composites, the properties of the in-situ polymerized modified glass fiber composites of the present invention have been improved to a greater extent: in the modification of the PA6 matrix, graphene oxide powder is added and thermally reduced in the subsequent process, and the PA6 polymerization process is carried out synchronously. Generally, the addition of graphene will cause a significant decrease in the impact strength and elongation at break of the composite material, and the toughness of the material will decrease. However, the preparation method of the present invention can avoid this problem because the consumption of water by graphene oxide and thermal reduction are carried out synchronously during the hydrolysis polymerization process of PA6. After further reinforcing and modifying PA6 with glass fiber, the impact strength is greatly improved. The decrease in the elongation at break of the composite material is due to the relatively high content of the reinforcing fiber. The reason for these effects is that after the graphene oxide powder dispersed in the PA6 matrix is thermally reduced, a synergistic reinforcement effect is generated with the glass fiber. The addition of graphene oxide powder improves the performance of the PA6 resin matrix, is beneficial to the polymerization of PA6, improves the interfacial bonding force between the glass fiber and PA6, and improves the stress transfer efficiency between the glass fiber and the matrix resin, thereby greatly improving the strength of the composite material. The glass fiber treated with the coupling agent has a more significant effect on enhancing the interfacial bonding. Another advantage of the in-situ polymerized composite material of the present invention is that the rGO on the surface of the glass fiber still has a typical wrinkled morphology. In addition to the mutual bridging and interlocking effect between functional groups, there is also a micron-scale mechanical interlocking effect in the wrinkled morphology between the graphene oxide components in the matrix, making the combination between the matrix and the reinforcing body more firm. Such a combined structure can also better prevent the corrosion of small molecules and improve the anti-corrosion performance of the material.

[0163] Regarding the heat distortion temperature, since the glass fiber has a higher heat resistance than the matrix, the addition of the glass fiber will increase the heat distortion temperature of the composite material. Moreover, ZnO@rGO is attached and modified on the surface of the glass fiber, and graphene oxide and the glass fiber synergistically enhance the heat distortion temperature of the material.

[0164] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Those with ordinary knowledge in the technical field to which the present invention pertains can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the scope defined in the claims.

Claims

1. A preparation method of a composite material frame based on in-situ polymerization, wherein the composite material frame is cut from a glass fiber reinforced nylon 6 composite material, and is characterized in that, The preparation method comprises the following steps: 1) Store the pretreated caprolactam after water removal and caprolactam in storage tanks A and B respectively; add the pretreated caprolactam and the catalyst sodium caprolactam into transfer tank A in proportion and mix evenly in transfer tank A, add caprolactam and the initiator bisacylated lactam-1,6-hexanediamine into transfer tank B and mix evenly in transfer tank B, and add the mixtures in transfer tanks A and B into a twin-screw extruder at a mass ratio of 1: (1 - 1.2) and at the same flow rate, and uniformly mix and extrude the mixed melt into a composite die through the twin-screw extruder; The composite die comprises an impregnation section, a reaction section, and a cooling section, and a heat insulation layer is arranged between the impregnation section and the reaction section; the mixed melt enters the impregnation section of the composite die from the twin-screw extruder; 2) Draw the modified glass fiber into the impregnation section of the composite die and impregnate it in the mixed melt; 3) Heat the modified glass fiber treated in step 2) to initiate in-situ polymerization of caprolactam adsorbed on the modified glass fiber, and then through rolling and cooling, the glass fiber reinforced nylon 6 composite material is obtained; 4) Continuously draw out the glass fiber reinforced nylon 6 composite material from the composite die under the action of a traction mechanism, cut it into required lengths, collect and package it, and finally assemble it to obtain the composite material frame; Among them, the preparation method of the modified glass fiber comprises the following steps: (1) Ultrasonic impurity removal Place the glass fiber in acetone and ultrasonicate for 30 min, then impregnate for 4 - 6 h, and then wash with deionized water; (2) Surface activation Immerse the glass fiber after ultrasonic impurity removal in step (1) above in an active impregnating solution for 6 - 8 h, then perform two immersions and two rolls, and then dry at 100 °C to obtain the modified glass fiber; among them, the active impregnating solution is prepared by uniformly mixing deionized water, absolute ethanol, and ZnO@rGO in a mass ratio of 85:9:

6.

2. The preparation method of a composite material frame based on in-situ polymerization according to claim 1, characterized in that, In step 1), the composition of the pretreated caprolactam and sodium caprolactam, wherein the molar concentration of sodium caprolactam is 1% - 3%; in step 1), the composition of caprolactam and bisacylated lactam-1,6-hexanediamine, wherein the molar concentration of bisacylated lactam-1,6-hexanediamine is 1% - 2.5%.

3. A preparation method of an in-situ polymerization composite material frame according to claim 2, characterized in that, The pretreated caprolactam comprises the following treatment steps: Add caprolactam and deionized water into a reaction kettle at a mass ratio of 100:30, stir evenly at a rotation speed of 200 - 500 rpm, and then add 0.5 - 3.5 parts of graphene oxide powder based on the weight parts of caprolactam, stir for 15 - 20 min, then evacuate for 15 min and introduce nitrogen for 15 min, and cycle at least three times; raise the temperature to 80 °C, continue stirring until the substances in the reaction kettle are completely melted, stabilize for 15 min, then raise the temperature to 200 °C, evacuate again for 15 min and introduce nitrogen for 15 min, and continue stirring for 6 - 8 h; after completion, the reaction kettle system returns to normal pressure, open the reaction kettle, take out the mixture, cool, dry, cut into pieces, and pulverize to obtain the pretreated caprolactam.

4. A method for preparing a composite material frame based on in-situ polymerization according to claim 3, characterized in that, The graphene oxide powder is formed by drying the graphene oxide solution, followed by grinding and screening, and its screening size ranges from 3 um to 53 um.

5. A preparation method of an in-situ polymerization composite material frame according to claim 1, characterized in that, The glass fiber is an alkali-free glass fiber with a linear density of 1200 - 9600 Tex.

6. The preparation method of a composite material frame based on in-situ polymerization according to claim 1, characterized in that, The temperatures of storage tank A and storage tank B are maintained at 110°C - 120°C, and the temperatures of transition tank A and transition tank B are maintained at 80°C - 100°C.

7. A preparation method of an in-situ polymerization composite material frame according to claim 1, characterized in that, The length of the impregnation section of the composite mold is 200 mm - 400 mm; the length of the reaction section is 500 mm - 1000 mm; the length of the cooling section is 300 mm - 500 mm.

8. A preparation method of an in-situ polymerization composite material frame according to claim 7, characterized in that, The temperature of the impregnation section is 80°C - 110°C; the temperature of the reaction section is 200°C - 260°C.

Images