Online treatment method for improving wettability of large-tow carbon fibers in pultrusion process

Abstract

An online treatment method for improving wettability of large-tow carbon fibers in a pultrusion process specifically comprises the steps that after large-tow carbon fibers or fabric is unwound through an unwinding device, large-tow carbon fiber bundles become fluffy through a vibration rod, and the distance between the fibers becomes large; carrying out surface modification treatment on the large-tow carbon fibers by adopting a double-sided nozzle plasma treatment process, so that chemical bonds on the surfaces of the carbon fibers are broken and recombined; and after being subjected to plasma surface treatment, the large-tow carbon fibers are led into the impregnation device to be combined with resin by the guide roller, and are led into the next pultrusion mold by the guide roller to be heated, cured and molded. According to the method, the large-tow carbon fibers are subjected to surface treatment through an online treatment process, so that the wettability of the large-tow carbon fibers in the pultrusion process and the binding property of the large-tow carbon fibers and resin are improved, and the advantage of continuous production of the pultrusion process is fully exerted; the wettability of the large-tow carbon fibers is improved, so that the mechanical property of the pultrusion composite material is further improved.

Description

Technical Field

[0001] The invention belongs to the field of fiber modification and composite material manufacturing, and in particular relates to an online processing method for improving the wettability of large-tow carbon fibers in a pultrusion molding process. Background Art

[0002] Carbon fiber is a fiber material with a carbon content of more than 95%, and has the advantages of high strength, high modulus, high temperature resistance and light weight. Usually, we call the carbon fiber bundle with a single fiber number greater than 24K "large tow carbon fiber".

[0003] Carbon fiber is usually combined with resin to prepare composite materials. Common composite material molding processes include autoclave molding, hand lay-up molding, resin transfer molding, pultrusion, etc. Among them, the pultrusion molding process has developed rapidly and achieved industrial application in recent years due to its simple operation, short process flow, high fiber utilization, high production efficiency and continuous production.

[0004] Pultruded carbon fiber composites are widely used in rail transit, wind turbine blades, sports facilities and other fields. In addition, in order to promote the development of carbon fiber composites in the civilian field, large-tow carbon fiber has attracted widespread attention due to its high cost-effectiveness. However, the lack of polar groups on the surface of carbon fiber, low surface energy, and chemical inertness lead to poor bonding with resins. In addition, large-tow carbon fiber contains more single fibers and thicker fiber bundles, making it difficult to achieve efficient and uniform impregnation of resins, which to some extent affects the rapid development of large-tow carbon fiber composites in related application fields. Therefore, various methods of carbon fiber surface treatment have been studied in recent years, including chemical grafting, surface oxidation, plasma treatment, cryogenic treatment, etc., by adding active functional groups on the surface of carbon fiber or increasing the surface roughness of carbon fiber to improve the wettability and surface binding ability of resin.

[0005] Among them, the plasma treatment method refers to the use of high-energy plasma to impact the surface of carbon fiber, break and reorganize the chemical bonds on the surface of carbon fiber, generate polar groups on the surface of carbon fiber and increase the surface roughness of carbon fiber. It is a fiber surface treatment method with simple operation, high efficiency and environmental friendliness.

[0006] Therefore, a simple and feasible method is needed to combine the characteristics of the pultrusion process and apply plasma to treat large-tow carbon fiber or large-tow carbon fiber fabric to achieve online improvement of the wettability of large-tow carbon fiber. Summary of the invention

[0007] The main problem to be solved by the present invention is to provide a method for improving the wettability of large-tow carbon fibers that is simple, feasible, efficient, environmentally friendly, and can be implemented in conjunction with a pultrusion process. The present invention can improve the resin wettability of large-tow carbon fibers in the pultrusion process, improve the surface bonding ability of large-tow carbon fibers with resins, and improve the comprehensive performance of their composite materials.

[0008] In order to solve the above problems, the present invention adopts the following solutions:

[0009] An online processing method for improving the wettability of large-tow carbon fiber in a pultrusion process comprises the following steps:

[0010] Step S1: The large-tow carbon fiber unwound by the unwinding mechanism generates high-frequency vibration through a high-frequency vibrating vibrating rod, so that the spacing between the fibers of the large-tow carbon fiber bundle increases during the vibration process, and the fiber bundle becomes fluffy;

[0011] Step S2: using a double-sided nozzle to perform surface plasma treatment on the large-tow carbon fiber or large-tow carbon fiber fabric, so that the surface of the large-tow carbon fiber undergoes chemical oxidation and physical etching, the chemical bonds on the surface of the large-tow carbon fiber are broken and reorganized, and the surface becomes rough; combined with the vibration of the vibration rod in step S1, the surface of the large-tow carbon fiber or large-tow carbon fiber fabric is treated evenly;

[0012] Step S3: the large-tow carbon fiber or large-tow carbon fiber fabric treated with surface plasma enters a dipping device through a guide roller to be combined with resin;

[0013] Step S4: The large-tow carbon fiber or large-tow carbon fiber fabric fully impregnated with resin enters the molding mold under the action of the guide roller, and the cured carbon fiber composite material is pulled out of the mold by the pulling device.

[0014] Preferably, the large-tow carbon fiber or large-tow carbon fiber fabric impregnated with resin according to the present invention is solidified and formed through three steps of impregnation, molding, and curing / cooling under a certain tensile force.

[0015] Preferably, the large-tow carbon fiber of the present invention refers to a carbon fiber bundle with a tow number greater than 24K, and the large-tow carbon fiber fabric refers to an orthogonal fabric or multi-axial warp knitted fabric prepared using large-tow carbon fiber as raw material.

[0016] Preferably, the vibration rod of the present invention realizes displacement change by up and down movement, and the vibration frequency of the vibration rod is 1-100 Hz and the vibration amplitude is 10-25 mm.

[0017] Preferably, the double-sided nozzle of the present invention is placed on the upper and lower surfaces of the large-tow carbon fiber or large-tow carbon fiber fabric at an angle of 0 to 90 degrees, and the upper and lower surfaces of the large-tow carbon fiber or large-tow carbon fiber fabric are treated at the same time to improve the surface treatment efficiency and effect; the double-sided nozzle is connected to the plasma generator through an air pipe respectively.

[0018] Preferably, the plasma treatment gas of the present invention includes at least one of air, oxygen, argon, ozone, nitrogen, hydrogen or a mixed gas, the plasma treatment rate is 100-500 mm / min, and the power is 200-400 W / 10 min.

[0019] Preferably, the resin of the present invention is a thermosetting resin, including at least one of epoxy resin, polyurethane resin, bismaleimide resin, vinyl resin and corresponding modified resins.

[0020] Preferably, the large-tow carbon fiber or large-tow carbon fiber fabric impregnated with resin of the present invention enters a molding mold for heating and curing, wherein the molding mold is heated in three zones and is pulled out of the mold by traction devices located on both sides of the composite material, and the forward speed of the traction device is 100-500mm / min.

[0021] In summary, the present invention uses plasma surface treatment of large-tow carbon fiber or large-tow carbon fiber fabric, improves the resin wettability of large-tow carbon fiber or large-tow carbon fiber fabric in the pultrusion process, and improves the surface bonding ability of large-tow carbon fiber and resin, thereby improving the comprehensive performance of pultruded large-tow carbon fiber composite materials. The method is simple to operate, highly feasible, has good surface treatment uniformity, high efficiency, and is pollution-free. It has significant economic and social benefits and is of great significance for promoting the application of large-tow carbon fiber composite materials.

[0022] Compared with the prior art, the technical solution of the present invention has the following innovative features and beneficial effects:

[0023] 1. The present invention controls the vibration frequency and amplitude of the vibration rod so that the large-tow carbon fiber fabric generates high-frequency vibration under the action of the vibration rod, and the spacing between the fibers of the large-tow carbon fiber bundle increases during the vibration process, and the fiber bundle becomes fluffy.

[0024] 2. The plasma treatment system of the present invention adopts a double-sided nozzle to perform surface treatment on the upper and lower surfaces of large-tow carbon fiber or large-tow carbon fiber fabric at the same time, thereby improving the surface treatment efficiency and combining the high-frequency vibration effect of the previous vibration rod to improve the uniformity of plasma treatment.

[0025] 3. The vibration rod and plasma treatment system of the present invention are combined with the pultrusion process, giving full play to the continuous production characteristics of the pultrusion process and realizing the surface treatment of large-tow carbon fibers online.

[0026] 4. The surface-treated large-tow carbon fiber or large-tow carbon fiber fabric of the present invention realizes efficient impregnation of the large-tow carbon fiber or fabric in the dipping device, and improves the surface bonding ability of the large-tow carbon fiber and the resin and the comprehensive performance of the pultruded composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of an online processing method for improving the wettability of large-tow carbon fibers in a pultrusion process according to the present invention.

[0028] Figure numerals: 1. large-tow carbon fiber unwinding system, 2. large-tow carbon fiber or large-tow carbon fiber fabric, 3. vibration rod, 4. first plasma generator 1, 5. first air pipe 1, 6. first plasma nozzle 1, 7. second plasma generator 2, 8. second air pipe 2, 9. second plasma nozzle 2, 10. glue injection machine, 11. glue injection pipeline, 12. glue injection head, 13. glue injection mold, 14. glue dipping tank, 15. molding mold, 16. traction device, 17. large-tow carbon fiber pultruded composite material. DETAILED DESCRIPTION

[0029] In order to make the features and technical solutions of the present invention more clearly understood, the present invention is further described below in conjunction with specific embodiments, and it should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

[0030] An online processing method for improving the wettability of large-tow carbon fiber in a pultrusion process comprises the following steps:

[0031] Step S1: The large-tow carbon fiber unwound by the unwinding mechanism generates high-frequency vibration through a high-frequency vibrating vibrating rod, so that the spacing between the fibers of the large-tow carbon fiber bundle increases during the vibration process, and the fiber bundle becomes fluffy;

[0032] Step S2: using a double-sided nozzle to perform surface plasma treatment on the large-tow carbon fiber or large-tow carbon fiber fabric, so that the surface of the large-tow carbon fiber undergoes chemical oxidation and physical etching, the chemical bonds on the surface of the large-tow carbon fiber are broken and reorganized, and the surface becomes rough; combined with the vibration of the vibration rod in step S1, the surface of the large-tow carbon fiber or large-tow carbon fiber fabric is treated evenly;

[0033] Step S3: the large-tow carbon fiber or large-tow carbon fiber fabric treated with surface plasma enters a dipping device through a guide roller to be combined with resin;

[0034] Step S4: The large-tow carbon fiber or large-tow carbon fiber fabric fully impregnated with resin enters the molding mold under the action of the guide roller, and the cured carbon fiber composite material is pulled out of the mold by the pulling device.

[0035] The pultrusion process of the present invention is a method for preparing a fiber-reinforced composite material, that is, large-tow carbon fiber or large-tow carbon fiber fabric impregnated with resin is solidified and formed through three steps of impregnation, molding, and curing / cooling under a certain tensile force.

[0036] The large-tow carbon fiber of the present invention refers to a carbon fiber bundle with a tow number greater than 24K, and the large-tow carbon fiber fabric refers to an orthogonal fabric or multi-axial warp knitted fabric prepared using large-tow carbon fiber as raw material.

[0037] The vibration rod of the present invention realizes displacement change by moving up and down, and the vibration frequency of the vibration rod is 1-100 Hz and the vibration amplitude is 10-25 mm.

[0038] The double-sided nozzle of the present invention is placed on the upper and lower surfaces of large-tow carbon fiber or large-tow carbon fiber fabric at an angle of 0 to 90 degrees, and simultaneously treats the upper and lower surfaces of the large-tow carbon fiber or large-tow carbon fiber fabric, thereby improving the surface treatment efficiency and effect; the double-sided nozzle is connected to the plasma generator through an air pipe respectively.

[0039] The plasma treatment gas of the present invention includes at least one of air, oxygen, argon, ozone, nitrogen, hydrogen or a mixed gas, and the large tow carbon fiber is surface treated by high-speed impact of plasma. These gases are non-toxic and harmless, and are environmentally friendly, so they belong to the category of green manufacturing technology. The plasma treatment rate is 100-500mm / min, and the power is 200-400W / 10min.

[0040] The resin of the present invention is a thermosetting resin, including at least one of epoxy resin, polyurethane resin, bismaleimide resin, vinyl resin and corresponding modified resins.

[0041] The resin-impregnated large-tow carbon fiber or large-tow carbon fiber fabric of the present invention enters a molding die for heating and curing, wherein the molding die is heated in three zones and is pulled out of the mold by pulling devices located on both sides of the composite material, and the forward speed of the pulling device is 100-500mm / min.

[0042] like Figure 1 As shown, the present application provides an online processing method for improving the wettability of large-tow carbon fiber in a pultrusion process, which is carried out in the following steps:

[0043] Step S1: After the large-tow carbon fiber or fabric 2 is unwound by the unwinding device 1 under constant tension conditions, the large-tow carbon fiber or fabric generates high-frequency vibration by the vibration rod 3 that vibrates up and down at high frequency, and the spacing between the fibers of the large-tow carbon fiber bundle becomes larger and fluffy during the vibration process, wherein the vibration frequency of the vibration rod is 1-100 Hz, and the vibration amplitude is 10-25 mm.

[0044] Step S2: Use a double-sided first plasma nozzle 6 and a second plasma nozzle 9 to simultaneously perform surface modification on large-tow carbon fiber or large-tow carbon fiber fabric, wherein the plasma nozzles are placed at a certain angle on the upper and lower sides of the large-tow carbon fiber, and the plasma is transported to the nozzles by the first plasma generator 4 and the second plasma generator 7 via the first air pipe 5 and the second air pipe 8. The gas in the plasma generator includes air, oxygen, argon, ozone, nitrogen, hydrogen or a mixed gas; the plasma treatment rate is 100-500mm / min, and the power is 200-400W / 10min; the high-frequency vibration of the front-end vibration device is combined to achieve the uniformity of the surface treatment of the large-tow carbon fiber.

[0045] Step S3: The large tow carbon fiber or large tow carbon fiber fabric after surface treatment enters the dipping system, which can be a closed mold injection mold 13 or a dipping tank 14, wherein the closed mold injection mold refers to a resin injection machine 10 that delivers the mixed resin to the injection head 12 through the injection pipe 11, and injects the resin under high pressure. The resin used to impregnate the large tow carbon fiber includes thermosetting resins such as epoxy resin, polyurethane resin, bismaleimide resin, vinyl resin and corresponding modified resins.

[0046] Step S4: The large-tow carbon fiber or large-tow carbon fiber fabric that has been fully impregnated with the resin enters the molding mold 15 for heating and curing, wherein the molding mold is heated in three zones, and then the prepared large-tow carbon fiber pultrusion molding composite material 17 is pulled out of the molding mold by the traction device 16, wherein the traction device is located on both sides of the composite material, clamps the composite material and pulls the molded composite material out of the molding mold under a certain pulling force, and the forward speed of the traction device is 100-500mm / min.

[0047] Example 1 Preparation of large tow carbon fiber pultruded composite material

[0048] The large-tow carbon fiber bundle on the unwinding rack is passed through the pultrusion die through a traction device, and the process parameters such as the vibration frequency and vibration amplitude of the vibration rod, the angle of the plasma nozzle, the plasma pretreatment rate, the curing mold temperature, and the traction speed are set. The polyurethane resin is injected using a closed mold injection process to prepare a large-tow carbon fiber pultrusion composite material.

[0049] Table 1 Related process parameters

[0050]

[0051] After plasma treatment, the wettability of large tow carbon fiber is improved, thereby improving the interface performance of pultruded composite materials. Therefore, the shear performance test of the prepared large tow carbon fiber pultruded composite material was carried out. After treatment, the interlaminar shear strength of the large tow carbon fiber pultruded composite material was 73.54MPa, and the interlaminar shear strength of the untreated large tow carbon fiber pultruded composite material was 59.23MPa, which was increased by 24.16%.

[0052] Example 2 Preparation of large-tow carbon fiber two-dimensional woven fabric pultrusion composite material

[0053] The large-tow carbon fiber two-dimensional woven fabric on the unwinding rack is passed through the pultrusion die through a traction device, and the process parameters such as the vibration frequency and vibration amplitude of the vibration rod, the angle of the plasma nozzle, the plasma pretreatment rate, the curing mold temperature, and the traction speed are set. The polyurethane resin is injected using the closed mold injection process to prepare the large-tow carbon fiber two-dimensional woven fabric pultrusion molding composite material.

[0054] Table 2 Related process parameters

[0055]

[0056] After plasma treatment, the wettability of large tow carbon fiber is improved, thereby improving the interface performance of pultruded composite materials. Therefore, the shear performance test of the prepared large tow carbon fiber two-dimensional woven fabric pultruded composite material was carried out. After treatment, the interlaminar shear strength of the large tow carbon fiber two-dimensional woven fabric pultruded composite material was 56.36MPa, and the interlaminar shear strength of the untreated large tow carbon fiber two-dimensional woven fabric pultruded composite material was 48.37MPa, which was increased by 16.52%.

[0057] Example 3 Preparation of large-tow carbon fiber multi-axial warp knitted fabric pultruded composite material

[0058] The large-tow carbon fiber multi-axial warp knitted fabric on the unwinding stand is passed through the pultrusion die through a traction device, and the process parameters such as the vibration frequency and vibration amplitude of the vibration rod, the angle of the plasma nozzle, the plasma pretreatment rate, the curing mold temperature, and the traction speed are set. The polyurethane resin is injected using the closed mold injection process to prepare the large-tow carbon fiber multi-axial warp knitted fabric pultrusion molding composite material.

[0059] Table 3 Related process parameters

[0060]

[0061] After plasma treatment, the wettability of large tow carbon fiber is improved, thereby improving the interface performance of pultruded composite materials. Therefore, the shear performance test of the prepared large tow carbon fiber multi-axial warp knitted fabric pultruded composite material was carried out. After treatment, the interlaminar shear strength of the large tow carbon fiber multi-axial warp knitted fabric pultruded composite material was 73.22MPa, and the interlaminar shear strength of the untreated large tow carbon fiber multi-axial warp knitted fabric pultruded composite material was 63.41MPa, which was increased by 15.47%.

[0062] The above embodiments are only preferred embodiments of the present invention and are not any formal or substantial limitations of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the present invention, and these improvements and supplements should also be regarded as the scope of protection of the present invention.

Claims

1. An online processing method for improving the wettability of large-tow carbon fiber in pultrusion process, characterized in that The following steps are involved: Step S1: The large-tow carbon fiber unwound by the unwinding mechanism generates high-frequency vibration through a high-frequency vibrating vibrating rod, so that the spacing between the fibers of the large-tow carbon fiber bundle increases during the vibration process, and the fiber bundle becomes fluffy; Step S2: using a double-sided nozzle to perform surface plasma treatment on the large-tow carbon fiber or large-tow carbon fiber fabric, so that the surface of the large-tow carbon fiber undergoes chemical oxidation and physical etching, the chemical bonds on the surface of the large-tow carbon fiber are broken and reorganized, and the surface becomes rough; combined with the vibration of the vibration rod in step S1, the surface of the large-tow carbon fiber or large-tow carbon fiber fabric is treated evenly; Step S3: the large-tow carbon fiber or large-tow carbon fiber fabric treated with surface plasma enters a dipping device through a guide roller to be combined with resin; Step S4: The large-tow carbon fiber or large-tow carbon fiber fabric fully impregnated with resin enters the molding mold under the action of the guide roller, and the cured carbon fiber composite material is pulled out of the mold by the pulling device.

2. The online processing method for improving the wettability of large-tow carbon fiber in pultrusion process according to claim 1, characterized in that: The large-tow carbon fiber or large-tow carbon fiber fabric impregnated with resin is solidified and formed through three steps of impregnation, molding, and curing / cooling under a certain tensile force.

3. The online processing method for improving the wettability of large-tow carbon fiber in pultrusion process according to claim 1, characterized in that: The large-tow carbon fiber refers to a carbon fiber bundle with a tow number greater than 24K, and the large-tow carbon fiber fabric refers to an orthogonal fabric or multi-axial warp knitted fabric prepared using large-tow carbon fiber as raw material.

4. The online processing method for improving the wettability of large-tow carbon fiber in pultrusion process according to claim 1, characterized in that: The vibration rod realizes displacement change by moving up and down, and the vibration frequency of the vibration rod is 1-100 Hz and the vibration amplitude is 10-25 mm.

5. The online processing method for improving the wettability of large-tow carbon fiber in pultrusion process according to claim 1, characterized in that: The double-sided nozzle is placed on the upper and lower surfaces of the large-tow carbon fiber or large-tow carbon fiber fabric at an angle of 0 to 90 degrees, and the upper and lower surfaces of the large-tow carbon fiber or large-tow carbon fiber fabric are treated at the same time to improve the surface treatment efficiency and effect; the double-sided nozzle is connected to the plasma generator through an air pipe respectively.

6. The online processing method for improving the wettability of large-tow carbon fiber in pultrusion process according to claim 1, characterized in that: The plasma treatment gas includes at least one of air, oxygen, argon, ozone, nitrogen, hydrogen or a mixed gas, the plasma treatment rate is 100-500 mm / min, and the power is 200-400 W / 10 min.

7. The online processing method for improving the wettability of large-tow carbon fiber in pultrusion process according to claim 1, characterized in that: The resin is a thermosetting resin, including at least one of epoxy resin, polyurethane resin, bismaleimide resin, vinyl resin and corresponding modified resins.

8. The online processing method for improving the wettability of large-tow carbon fiber in pultrusion process according to claim 1, characterized in that: The resin-impregnated large-tow carbon fiber or large-tow carbon fiber fabric enters a molding mold for heating and curing, wherein the molding mold is heated in three zones and is pulled out of the mold by pulling devices located on both sides of the composite material, and the forward speed of the pulling device is 100-500mm / min.

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