Patent Application
20250075379
This application claims the benefit of Korean Patent Application No. 10-2023-0118361, filed on Sep. 6, 2023, which application is hereby incorporated herein by reference.
The present invention relates to a method for manufacturing high-tensile carbon continuous fiber spun yarn using a recycled carbon fiber and the spun yarn.
Global carbon reduction policies and stricter fuel efficiency regulations have led to increases in the number of eco-vehicles, including electric vehicles (EVs) and hydrogen vehicles (FCEV: Fuel Cell Electric Vehicle), and increases in the demand for carbon fiber reinforced plastic (CFRP) to reduce weights of vehicle body components in view of fuel efficiency. In addition, the demand for CFRP is increasing in various industrial fields that require high strength and light weight, such as aircrafts, bicycles, missiles, ultra-light blades for wind power generation, and medical devices. The increase in demand for CFRP generates a large amount of wastes, along with an increase in the cost of carbon fiber.
In the past, CFRP waste was difficult to dispose of due to the persistent nature of a thermosetting resin, so it was dumped in landfills. However, dumping in landfills has been banned due to recent stricter environmental regulations, and waste carbon fiber is now recovered by thermal burning or chemical decomposition.
Accordingly, in the related art, the recovered waste carbon fiber (hereinafter, referred to as “recycled carbon fiber”) is reused by recycling it in the form of short fibers such as chops, pellets, or non-woven mats. However, the recycled carbon fiber of the related art can only produce carbon fiber in the form of short fibers, so it can be applied only to short fiber composite methods such as SMC and has limitations in being unable to be applied to high-performance components.
For example, automobile manufacturers use high-performance (high value-added) methods such as a CFRP winding (CFRP filament winding) method for manufacturing a high-pressure hydrogen tank for a hydrogen vehicle (FCEV) and a pultrusion method for manufacturing CFRP vehicle body components for an electric vehicle (EV) (for example, CFRP sheet cross member). For such a high-performance method, an expensive high-tensile carbon continuous fiber that satisfies high tensile strength (strength to resist tension) is necessarily required. However, the carbon fiber in the form of short fibers produced by the recycling method of the related art has a low tensile strength and thus cannot be applied to the high-performance method.
On the other hand, the carbon fiber has high brittleness and thus cannot be processed into a carbon fiber spun yarn. Therefore, a method is used in which a worsted spinning process is performed so that high-ductility short fiber-type flame-retardant fiber, which is an intermediate in the production of carbon fiber, is used to enable fibers to have a cohesive force, resulting in flame-retardant fiber spun yarn with discontinuity characteristics.
However, the high-ductility short fiber-type flame-retardant fiber has disadvantages in that its rigidity is greatly reduced during heat treatment, and its tensile strength is very low when manufactured in the form of continuous fiber spun yarn due to its low rigidity. As a result, there is a problem that the flame-retardant fiber cannot be used in the winding and pultrusion methods required to manufacture CFRP vehicle components such as the CFRP hydrogen tank and the CFRP sheet cross member.
In addition, the flame-retardant fiber has the disadvantage of increasing manufacturing equipment, costs, and complexity of the manufacturing process due to the additional process for heat treatment.
Therefore, a carbon fiber recycling method applicable to high-performance methods such as CFRP winding and CFRP pultrusion is urgently needed.
The matters described in the background section are prepared to enhance understanding of the background of embodiments of the invention and may include matters that are not already known.
The present invention relates to a method for manufacturing high-tensile carbon continuous fiber spun yarn using a recycled carbon fiber and the spun yarn. Particular embodiments relate to a method for manufacturing a high-tensile carbon continuous fiber spun yarn including a recycled carbon fiber (rCF) recovered from wastes.
An exemplary embodiment of the present invention provides a method for manufacturing a high-tensile continuous fiber spun yarn using a recycled carbon fiber, which can manufacture a high-tensile continuous fiber spun yarn with excellent tensile strength in a long length by using a recycled carbon fiber (rCF) raw material recovered from a composite material (CFRP) waste and is applicable to a high-performance/high value-added method such as CFRP winding and pultrusion, and the spun yarn.
According to an embodiment of the present invention, there is provided a method for manufacturing a high-tensile continuous fiber spun yarn using a recycled carbon fiber, the method including recovering a recycled carbon fiber (rCF) raw material from a waste composite material (CFRP) product, fabricating a recycled carbon fiber nonwoven fabric by using the recovered rCF raw material, producing slitter yarns cut into a long length and a predetermined narrow width by putting the rCF nonwoven fabric into a slitting process, fabricating a high-tensile continuous fiber spun yarn with a predetermined thickness by twisting at least one slitter yarn through a twisting process, and producing a spun yarn product by winding the high-tensile continuous fiber spun yarn on a bobbin.
In addition, the recovering the recycled carbon fiber raw material may include separating only a carbon fiber portion from a CFRP filament winding obtained by cutting the waste composite material product and recovering the recycled carbon fiber raw material in a form of short fibers by treating the separated carbon fiber along with a formic acid, a hydrogen peroxide, and a surfactant through a raw material recovery process.
In addition, the raw material recovery process may include performing a pretreatment by putting the separated carbon fiber into a pretreatment tank and reacting the same with the formic acid, the hydrogen peroxide, and the surfactant to penetrate and expand, performing a cleaning by putting the pretreated carbon fiber into a cleaning container and cleaning the same under constant normal pressure and low temperature conditions, and performing a main treatment by putting the cleaned carbon fiber into a main treatment tank and subjecting the same to a chemical reaction using the formic acid, the hydrogen peroxide, and the surfactant to recover the rCF raw material in the form of short fibers.
In addition, the fabricating the recycled carbon fiber nonwoven fabric may include performing a disintegration by putting the recovered rCF raw material into pulper equipment and mixing the recovered recycled carbon fiber with water to disintegrate the same, performing a beating by putting the rCF raw material subjected to the disintegration into refiner equipment and crushing the fiber with physical force to spread the crushed fibers in a unit of strand, performing a web forming by spraying the rCF raw material subjected to the beating onto a wire with finely sized meshes to remove part of the water and form a nonwoven fabric, an input amount of the raw material being adjusted to produce a rCF nonwoven fabric of predetermined thickness and basis weight, performing a dewatering by compressing the rCF nonwoven fabric subjected to the web forming to remove moisture, performing a drying process by removing all remaining moisture with dry air heated using a cylinder dryer device after the dewatering, and winding the dried rCF nonwoven fabric onto a spool.
In addition, the method may further include fabricating a roll-shaped carbon fiber nonwoven fabric product without a wrinkle through a rewinding process of rewinding the wound rCF nonwoven fabric through a plurality of rollers, after the winding.
In addition, in the disintegration, as a disintegration condition, 97.5% of water and 2.5% of the rCF raw material are mixed.
In addition, in the web forming, the rCF nonwoven fabric is subjected to a web forming process under conditions of a feed speed of 1.5 m/min and a raw material supply amount of 60 to 80 g per unit, which are set to increase a bonding force between short fibers and a rigidity.
In addition, in the winding, the dried rCF nonwoven fabric is continuously wound on the spool at a speed of 1.5 m/min, which is the same as the feed speed in the web forming process.
In addition, in the producing the slitter yarns, the slitter yarns are produced by evenly cutting the rCF nonwoven fabric under slitting conditions of a set width of 10 mm and a winding speed of 70 to 100 m/min.
In addition, in the producing the high-tensile continuous fiber spun yarn, the high-tensile continuous fiber spun yarn of which a thickness satisfies 0.7 mm is produced by twisting the slitter yarns into a predetermined pattern.
According to an embodiment of the present invention, there is provided a high-tensile continuous fiber spun yarn including a rCF, the high-tensile continuous fiber spun yarn being manufactured by a method including recovering a rCF raw material from a waste composite material (CFRP) product, fabricating a rCF nonwoven fabric by using the recovered rCF raw material, producing slitter yarns cut into a long length and a predetermined narrow width by putting the rCF nonwoven fabric into a slitting process, fabricating a high-tensile continuous fiber spun yarn with a predetermined thickness by twisting at least one slitter yarn through a twisting process, and producing a spun yarn product by winding the high-tensile continuous fiber spun yarn on a bobbin.
According to an exemplary embodiment of the present invention, a high-tensile continuous fiber spun yarn with excellent tensile strength in a continuous length is manufactured using a rCF as a raw material and applied to a high-performance method such as CFRP winding and pultrusion, making it possible to reduce the production cost of a CFRP product using an expensive natural carbon fiber as a raw material.
In addition, by recycling CFRP waste, which is difficult to dispose of due to its persistent nature, and manufacturing an expensive CFRP component by using a high-performance method, it is possible to achieve effects of reducing waste disposal costs and reducing vehicle manufacturing costs in an eco-friendly manner.
In the following detailed description, only certain exemplary embodiments of the present invention have been shown and described, simply by way of illustration.
The terminology used herein is for the purpose of describing specific exemplary embodiments only and is not intended to be limiting of the present invention. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in the present specification, specify the presence of stated features, integers, steps, operations, constitutional elements, and/or components, but they do not preclude the presence or addition of one or more other features, integers, steps, operations, constitutional elements, components, and/or groups thereof. As used herein, the term “and/or” includes any one or all combinations of the associated listed items.
Throughout the specification, terms such as first, second, A, B, (a), (b), etc. may be used to describe various constitutional elements, but the constitutional elements should not be limited by the terms. The terms are only used to distinguish the constitutional elements from other constitutional elements, and the nature, sequence, or order of the corresponding constitutional element is not limited by the term.
Throughout the specification, when it is mentioned that a certain constitutional element is “connected” or “coupled” to another constitutional element, it should be understood that the certain constitutional element may be directly connected or coupled to the other constitutional element or another intervening constitutional element may be present therebetween. Conversely, when it is mentioned that a certain constitutional element is “directly connected” or “directly coupled” to another constitutional element, it should be understood that there is no intervening constitutional element present therebetween.
The terms throughout the specification are merely used to describe specific exemplary embodiments of the present invention but are not intended to limit the present invention. The singular forms “a,” “an,” and “the” are intended to include plural forms as well, unless the context clearly indicates otherwise.
Additionally, it is understood that one or more of the methods or aspects thereof described below may be executed by at least one or more control units or controllers. The term “controller” may refer to a hardware device that includes a memory and a processor. The memory is configured to store program instructions and the processor is specially programmed to execute the program instructions so as to perform one or more processes described in more detail below. The controller, as described herein, may control operations of units, modules, components, devices, or the like. It is also understood that the methods below may be executed by a device that includes a control unit along with one or more other components, as will be appreciated by one skilled in the art.
Now, a method for manufacturing a high-tensile continuous fiber spun yarn using a recycled carbon fiber according to exemplary embodiments of the present invention will be described in detail with reference to the drawings.
Referring to
The waste composite material products includes a waste hydrogen tank, a waste CFRP vehicle body component including a waste CFRP sheet cross member, and a manufacturing waste generated during production of a CFRP product.
Hereinafter, steps of an embodiment method for manufacturing a high-tensile continuous fiber spun yarn will be described in detail through the drawings.
Referring to
Specifically, the method (S20) for recovering a recycled carbon fiber raw material includes cutting the waste composite material (CFRP) product through cutter equipment 140 (S21) and separating only carbon fiber portions from the cut CFRP filament winding through a separator 145 (S22). For example, after cutting a waste hydrogen tank for an FCEV (hydrogen electric vehicle) and separating it into a large amount of CFRP filament windings, the glass fiber on the outer surface thereof may be physically removed through the separator 145 to extract only the carbon fiber portion.
Then, through a raw material recovery process, the separated carbon fiber is chemically treated with a formic acid, hydrogen peroxide, and a surfactant to recover a recycled carbon fiber (rCF) raw material in the form of short fibers (S23).
In this case, the raw material recovery process (S23) may include a pretreatment step (S23-1) of putting the separated carbon fiber into a pretreatment tank 150 and reacting the same with the formic acid, the hydrogen peroxide, and the surfactant to penetrate and expand, a cleaning step (S23-2) of putting the pretreated carbon fiber into a cleaning container 160 and cleaning the same under constant normal pressure (1 atm) and low temperature (<100° C.) conditions (environments), and a main treatment step (S23-3) of putting the cleaned carbon fiber into a main treatment tank 170 and subjecting the same to a chemical reaction using the formic acid, the hydrogen peroxide, and the surfactant to recover the rCF raw material 11 in the form of short fibers (S24).
The raw material recovery process (S23) has process features of being carried out in the normal pressure and low temperature environments to reduce initial equipment and maintenance costs, and reducing pollutant emissions by using the formic acid and the hydrogen peroxide. In addition, the raw material recovery process has the feature of enabling upcycling by recovering an epoxy resin from a remaining waste solution residue after the rCF raw material 11 has been recovered.
Note that
Referring to
The method for fabricating the rCF nonwoven fabric 12 may be described as corresponding to the detailed process of step S30 in
Specifically, the method (S30) for manufacturing the rCF nonwoven fabric 12 includes a disintegration step (S31) of putting the rCF raw material 11 recovered in the preceding process into pulper equipment 180 and mixing the raw material with water to disintegrate the same, a beating step (S32) of putting the rCF raw material 11 subjected to the disintegration step into refiner equipment 190 and crushing the carbon fiber with physical force in the refiner equipment to spread the crushed fibers in a unit of strand, a raw material feeding step (S33) of feeding the rCF raw material 11 subjected to the beating step for fabricating a nonwoven fabric, a web forming step (S34) of spraying the fed rCF raw material 11 onto a wire 200 with finely sized meshes to remove part of the water and form a nonwoven fabric, in which an input amount of the raw material is adjusted to produce a rCF nonwoven fabric 12 of predetermined thickness and basis weight, a dewatering step (S35) of compressing the rCF nonwoven fabric 12 subjected to the web forming step to remove moisture by compression equipment 210, a drying step (S36) of removing all remaining moisture with dry air heated using a cylinder dryer device 220 after the dewatering, and a winding step (S37) of winding the dried rCF nonwoven fabric 12 onto a spool 230.
In addition, the method may further include a rewinding step (S38) of rewinding the wound rCF nonwoven fabric 12 through a plurality of rollers 240, after the winding step (S37), making it possible to produce a roll-shaped rCF nonwoven fabric product without a wrinkle.
Hereinafter, the description of steps of the method for fabricating the rCF nonwoven fabric 12 will be continued.
The disintegration step (S31) is a disintegration process of stirring and evenly dispersing the partially agglomerated rCF raw material 11 in pulper equipment 180. In this case, embodiments of the present invention include mixing 97.5% of water and 2.5% of rCF raw material as an optimal disintegration condition derived through repeated experiments. Considering the physical properties of the rCF raw material 11, unlike a wood pulp raw material for making traditional Korean paper, the rCF raw material is not hygroscopic and is stable as it is not affected by moisture. However, the rCF raw material has lower dispersibility when disintegrated, compared to the wood pulp raw material. Therefore, upon mixing, the proportion of water should be increased. Therefore, compared to the typical traditional Korean paper of 90% of water and 10% of wood pulp, the mixing may be performed under optimal values of 97.5% of water and 2.5% of rCF raw material as a disintegration condition.
In addition, the beating step (S32) is a beating process in which the rCF raw material 11 is made into short fibers and separated into individual fibers because each fiber strand has a different length. In general, a wood pulp raw material undergoes several beating processes (primary, secondary, etc.) due to the large length variation among fibers. On the other hand, the rCF raw material 11 of embodiments of the present invention has a smaller length deviation among fibers compared to the wood pulp raw material, which allows only a single beating process to be performed.
The disintegration process and the beating process may be collectively referred to as a blending process, which is a process of evenly blending raw materials before making a nonwoven fabric (traditional Korean paper). In general, a wood pulp raw material is mixed with an adhesive such as paper mulberry paste or paper mulberry glue to make traditional Korean paper after the beating process. However, the rCF raw material 11 is not mixed with an adhesive because it has the property that the bond between short fibers is weakened when mixed with an adhesive, resulting in lower rigidity.
In addition, a wood pulp raw material is treated with a wet strength agent and a fixative in order to improve the rigidity and bonding properties of fibers. However, for the rCF raw material 11 of embodiments of the present invention, the fiber itself has excellent rigidity and bonding strength between fibers, making it possible to omit the wet strength agent and fixative treatments.
In addition, the web forming step (S34) refers to a web forming process of determining a thickness of the rCF nonwoven fabric 12 by adjusting an input amount of the rCF raw material 11, and it is an important process for the quality and strength of the rCF nonwoven fabric 12.
In the case of a general wood pulp raw material, the web forming is performed under conditions of a feed speed of wood pulp of 100 m/min and a raw material supply amount of about 13 g per unit. However, in the case of the rCF raw material 11 of embodiments of the present invention, the feed speed should be lower because only the bonding force of short fibers is used without using an adhesive.
Accordingly, the rCF nonwoven fabric 12 according to an exemplary embodiment of the present invention is produced through the web forming process under the conditions of a feed speed of 1.5 m/min and a raw material supply amount of 60 to 80 g per unit, which are optimized through experimentation to increase the bonding force between short fibers and rigidity.
The winding step (S37) refers to a winding process of continuously winding the dried (finished) rCF nonwoven fabric 12 on a spool 230, and it includes winding the fabric at a speed of 1.5 m/min, which is the same as the feed speed in the web forming process.
Note that a method for manufacturing a substantial high-tensile continuous fiber spun yarn using the previously completed rCF nonwoven fabric 12 will be described in more detail.
The high-tensile continuous fiber spun yarn 14 manufactured according to an exemplary embodiment of the present invention means that short fibers are twisted to form a long continuous fiber while securing bonding strength between short fibers. The rCF nonwoven fabric 12 fabricated for manufacturing the high-tensile continuous fiber spun yarn 14 has already been given bonding strength through the fabricating process thereof. Therefore, the high-tensile continuous fiber spun yarn 14 is produced in the form of a long yarn with a twist pattern through a twisting process using the traditional Korean paper yarn manufacturing method, thereby having a quality that can be applied to a high-performance method.
For example, in the step (S40) of generating the slitter yarn 13 through the slitting process of
Here, the characteristics required to be satisfied as conditions for applying a rCF spun yarn to a high-performance (high value-added) method according to embodiments of the present invention include thin thickness, high rigidity, and high resin impregnation. If the rCF spun yarn is thick (for example, 15 mm or greater), a space between the spun yarns becomes large, which may reduce resin impregnation and rigidity when molded using a high-performance method. Therefore, as a result of repeated experiments, a result (data) was derived that cutting the width of the slitter yarn 13 to 10 mm is most suitable for securing rigidity and making thin spun yarn.
In addition, in the step (S50) of fabricating the high-tensile continuous fiber spun yarn 14 of
Note that
Referring to
According to an exemplary embodiment of the present invention, a high-tensile continuous fiber spun yarn with excellent tensile strength in a continuous length is manufactured using a rCF as a raw material and applied to a high-performance method such as a CFRP winding and a pultrusion, making it possible to reduce the production cost of a CFRP product using an expensive natural carbon fiber as a raw material.
In addition, by recycling CFRP waste, which is difficult to dispose of due to the persistent nature, and by manufacturing an expensive CFRP component by using a high-performance method, it is possible to achieve effects of reducing waste disposal costs and reducing vehicle manufacturing costs in an eco-friendly manner.
The exemplary embodiments of the present invention are not implemented only through the devices and/or methods described above, but they may also be implemented through a program for realizing functions corresponding to the configuration of the exemplary embodiments of the present invention, a recording medium on which the program is recorded, and the like. Such implementation can be easily realized by one skilled in the art to which the present invention belongs, based on the exemplary embodiments described above.
Although the exemplary embodiments of the present invention have been described in detail, the scope of the present invention is not limited thereto, and various modifications and improvements made by one skilled in the art by using the basic concepts of the embodiments of the present invention defined in the following claims also fall within in the scope of the present invention.
The following reference identifiers may be used in connection with the figures to describe various features of embodiments of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2023-0118361 | Sep 2023 | KR | national |
