KR102358401B1 - Coating agents for carbon fibers and carbon fiber reinforced composites using the same - Google Patents

Abstract

The present invention includes an epoxy resin containing ethylene oxide and an additive having a functional group that reacts with ethylene oxide, and Fourier transform infrared spectroscopy (FT-IR) measurement results of 3,420 cm ^-1 after heat treatment at 230 ° C. or higher, 30 minutes or longer A carbon having a peak increase rate of 2.5 to 5 times, a peak increase rate near 1,730 cm ^-1 of 2.3 to 5 times, a peak increase rate near 1,000 cm ^-1 of 1.1 to 2.1 times, and a peak increase rate near 940 cm ^-1 of 1.2 to 3 times. It relates to a fiber coating agent and a carbon fiber reinforced composite material manufactured using the same.

Description

Carbon fiber coating agent and carbon fiber reinforced composite material using the same

The present invention relates to a carbon fiber reinforced composite material with improved impact strength, and more particularly, to a carbon fiber coating agent for improving impact strength and a carbon fiber reinforced composite material in which the carbon fiber coating agent is treated on the surface of the carbon fiber.

Conventionally, carbon fiber is used as a high-performance material in various industrial fields because of its excellent strength, heat resistance, impact resistance and chemical resistance. Excellent mechanical like this. Carbon fibers with chemical properties are used by themselves, but are generally used as carbon fiber reinforced composites (CFRP) by impregnating a matrix resin. Carbon fiber reinforced composite materials are light in weight and have very high mechanical strength such as strength and modulus of elasticity. It is used as a substitute for a new material, used for special purposes or expensive products, but its use continues to expand recently. In particular, in fields that require both light weight and rigidity, such as automobiles and airplanes, the demand for CFRP is increasing.

However, the carbon fiber-reinforced composite material has a disadvantage in that it is relatively weak in brittleness compared to metal or aramid, glass fiber and high-density polyethylene fiber-reinforced composite material. Accordingly, when applied to the purpose of absorbing or alleviating impact, such as an actual helmet, carbon fiber is not used alone, but is used together with aramid fiber, glass fiber, and high-density polyethylene fiber, which are high-performance fibers with excellent impact strength, or carbon fiber reinforced composite material. Instead, metal or other plastic materials are often used. In addition, in the case of low-cost carbon fiber-reinforced composite material, thermoplastic pellets have excellent properties such as tensile strength and flexural modulus, but have low impact strength. Physical properties other than strength greatly exceed the standard value.

On the other hand, as a method for improving the physical properties of CFRP, there is a method for improving the physical properties of CFRP by sizing using a chemically similar component to a specific matrix resin when producing carbon fibers, or a surface treatment method for chemically or physically treating the surface of carbon fiber. have. Among these surface treatment methods, there are methods such as anodization, plasma treatment, and ozone treatment, but all of these methods remove the sizing agent from the carbon fiber, so they are vulnerable to troubles during the process, and some surface treatment methods lose their effectiveness quickly. Post-processing requirements follow.

Republic of Korea Patent Publication No. 10-2004-0021649

The present invention has been devised to solve the above problems, and an object of the present invention is to minimize carbon fiber damage during the carbon fiber reinforced composite material molding process and improve compatibility with matrix resin, and a carbon fiber coating agent using the same To provide a carbon fiber reinforced composite material.

In addition, another object of the present invention is to provide a carbon fiber coating agent with improved impact strength through a coating agent that enhances adhesion between carbon fibers and a matrix resin, and a carbon fiber reinforced composite material using the same.

In addition, another object of the present invention is a carbon fiber coating agent capable of compensating for the disadvantages of the mechanical properties of the existing CFRP through a composite material with improved impact strength, and reducing the amount of carbon fiber used to lower the manufacturing cost of the carbon fiber reinforced composite material. And to provide a carbon fiber reinforced composite material using the same.

These and other objects and advantages of the present invention will become apparent from the following description of preferred embodiments.

The above object is achieved by a carbon fiber coating agent comprising an epoxy resin containing ethylene oxide and an additive having a functional group that reacts with ethylene oxide.

Preferably, the carbon fiber coating agent has a Fourier transform infrared spectroscopy (FT-IR) measurement result after heat treatment at 230 ° C. or higher for 30 minutes or more, and the peak increase rate near 3,420 cm ^-1 is 2.5 to 5 times, and the peak near 1,730 cm ^-1 The increase rate may be 2.3 to 5 times, the peak increase rate near 1,000 cm ⁻¹ may be 1.1 to 2.1 times, and the peak increase rate near 940 cm ⁻¹ may be 1.2 to 3 times.

Preferably, the additive may further include a fatty acid that is combined with the matrix resin when the carbon fiber reinforced composite material is molded.

Preferably, 1 to 7 parts by weight of the additive may be included with respect to 100 parts by weight of the solid content of the epoxy resin.

In addition, the above object is a carbon fiber reinforced composite material comprising an epoxy resin containing ethylene oxide and a carbon fiber coated with a carbon fiber coating agent containing an additive having a functional group reacting with ethylene oxide and a matrix resin impregnated in the carbon fiber. achieved by

Preferably, the carbon fiber coating agent has a Fourier transform infrared spectroscopy (FT-IR) measurement result after heat treatment at 230 ° C. or higher for 30 minutes or more, and the peak increase rate near 3,420 cm ^-1 is 2.5 to 5 times, and the peak near 1,730 cm ^-1 The increase rate may be 2.3 to 5 times, the peak increase rate near 1,000 cm ⁻¹ may be 1.1 to 2.1 times, and the peak increase rate near 940 cm ⁻¹ may be 1.2 to 3 times.

Preferably, the carbon fiber coating agent may include 1 to 7 parts by weight of the additive based on 100 parts by weight of the solid content of the epoxy resin.

Preferably, the additive may further include a fatty acid that is combined with the matrix resin when the carbon fiber reinforced composite material is molded.

Preferably, 50 to 900 parts by weight of the matrix resin may be included with respect to 100 parts by weight of the carbon fiber.

Preferably, the carbon fiber coated with the carbon fiber coating agent may be coated with 0.9 to 1.2 wt % of the carbon fiber coating agent.

Preferably, the matrix resin may include at least one of polyamide 6, polyamide 6,6, polyamide 6,10, polyamide 11, polyamide 12 and polyamide 4,6.

Preferably, the matrix resin is polyamide 6, polyamide 6,6, polyamide 6,10, polyamide 11, polyamide 12 and polyamide 4,6 in 100 parts by weight of polyamide resin comprising at least one of polyamide 4,6. 5 to 30 parts by weight of an acrylonitrile-butadiene-styrene (ABS) resin may be mixed.

Preferably, when the carbon fiber reinforced composite material is in the form of long fiber reinforced pellets, the impact strength of the carbon fiber reinforced composite material measured by the IZOD impact test based on ASTM D 235 is a carbon fiber without a carbon fiber coating agent. It may be improved by 4.6 to 13% compared to the manufactured carbon fiber reinforced composite material of the same type.

Preferably, when the carbon fiber reinforced composite material is in the form of a unidirectional prepreg, the impact strength of the carbon fiber reinforced composite material measured by the IZOD impact test based on ASTM D 235 is made of carbon fiber that is not coated with a carbon fiber coating agent It may be improved by 8 to 24.5% compared to the carbon fiber reinforced composite material of the same type.

Preferably, the specific gravity of the carbon fiber may be 1.7 to 1.9.

In addition, the above object is to prepare a carbon fiber coating agent by mixing an epoxy resin containing ethylene oxide and an additive having a functional group that reacts with ethylene oxide; It is achieved by a method for producing a carbon fiber-reinforced composite material comprising the step of, drying the coated carbon fiber, and impregnating the dried carbon fiber in a matrix resin to prepare a carbon fiber-reinforced composite material.

Preferably, in the water-dispersed coating solution, the solid content of the epoxy resin may be 1 to 5 wt% of the total water-dispersed coating solution.

Preferably, the drying step includes a primary drying step of drying at a temperature of 100° C. to 180° C. for 2 to 5 minutes and a secondary drying step of drying at a temperature of 200° C. to 260° C. for 1 to 2 minutes. it could be

More preferably, the primary drying step may be a step of drying at a temperature of 105° C. to 150° C. for 2 to 5 minutes, and the secondary drying step may be a step of drying at 220° C. to 240° C. in less than 100 seconds.

The carbon fiber coating agent and the carbon fiber reinforced composite material using the same according to an embodiment of the present invention minimize carbon fiber damage during the composite material molding process, improve compatibility with the matrix resin, and compare with the conventional carbon fiber reinforced composite material. Impact strength can be improved.

In addition, the carbon fiber coating agent and the carbon fiber reinforced composite material using the same according to an embodiment of the present invention compensate for the disadvantages of the mechanical properties of the existing CFRP through the composite material with improved impact strength, and the amount of carbon fiber used as needed is reduced. can reduce manufacturing cost.

However, the effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.

1 is a flowchart illustrating a method of manufacturing a carbon fiber reinforced composite material according to another aspect of the present invention.
2 is a comparison result of FT-IR before and after the reaction of the carbon fiber coating agent according to Example 1.
3 is a comparison result of FT-IR before and after the reaction of the carbon fiber coating agent according to Example 3.
4 is a comparison result of FT-IR before and after the reaction of the carbon fiber coating agent according to Example 5.
5 is a result of comparing the FT-IR change according to the heat treatment time of Examples 1, 3, and 5.

With reference to the accompanying drawings, the embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein.

In order to clearly express various layers and regions in the drawings, the thicknesses are enlarged. Throughout the specification, like reference numerals are assigned to similar parts. When a part, such as a layer, film, region, plate, etc., is “on” another part, it includes not only cases where it is “directly on” another part, but also cases where there is another part in between. Conversely, when we say that a part is "just above" another part, we mean that there is no other part in the middle.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control. Also, although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described herein.

The carbon fiber coating agent (or coating composition) according to an aspect of the present invention may include an epoxy resin containing ethylene oxide and an additive having a functional group reacting with ethylene oxide. Here, the epoxy resin is preferably a water-based epoxy.

In one embodiment, the additive included in the carbon fiber coating agent may have excellent compatibility with ethylene oxide of the epoxy resin or a functional group capable of reacting. If the ethylene oxide group has excellent compatibility or does not react as a functional group of an additive capable of reacting, the degree of freedom of the additive increases, which is advantageous for the binder function between carbon fiber and matrix resin, so a hydroxyl group (-OH) with relatively low reactivity is preferable

In one embodiment, the additive may further include a fatty acid functional group, and the fatty acid functional group induces binding with the matrix resin when the carbon fiber-reinforced composite material is molded by impregnating the carbon fiber coated with the carbon fiber coating agent into the matrix resin. .

In one embodiment, the carbon fiber coating agent is preferably 1 to 7 parts by weight of the additive based on 100 parts by weight of the solid content of the epoxy resin, more preferably 3 to 5 parts by weight. When the additive is less than 1 part by weight, it is difficult to improve the physical properties due to insufficient binder material between the carbon fiber and the matrix resin. For example, when the additive is more than 7 parts by weight, the carbon fiber has a hard property after curing, so that the friction resistance of the carbon fiber is lowered or the degree of freedom of the additive is low, so it is difficult to expect a binder role between the carbon fiber and the matrix resin. On the other hand, when the additive is 1 to 7 parts by weight, the liquid is maintained even after heat treatment without a special reaction, so that damage to the fibers due to contamination of equipment or lumps does not occur during heat treatment.

In one embodiment, the carbon fiber coating agent has a Fourier transform infrared spectroscopy (FT-IR) measurement result after heat treatment at 230 ° C. or more, 30 minutes or more, and the peak increase rate in the vicinity of 3,420 cm ^-1 is 2.5 to 5 times, and 1,730 cm ^-1 in the vicinity of It is preferable that the peak increase rate is 2.3 to 5 times, the peak increase rate near 1,000 cm ^-1 is 1.1 to 2.1 times, and the peak increase rate near 940 cm ^-1 is 1.2 to 3 times. Here, as a result of FR-IR measurement of the carbon fiber coating agent, that is, if the FT-IR peak growth is smaller than the above value, there are too few functional groups capable of binding, so there is little effect of improving physical properties. As a side effect, there is a problem of process contamination and fiber damage due to the hardened core.

More specifically, when the peak growth according to the Fourier transform infrared spectroscopy (FT-IR) measurement result is less than the above range, the improvement of the physical properties of CFRP is low due to insufficient additives, and when the peak growth exceeds the above range, the reactivity is large. Excessive reaction between the materials (water-based epoxy and additives) is induced, and the orientation freedom of the additives is lowered, the improvement of the physical properties of CFRP is low, and the reactive materials may act as impurities.

The above-mentioned carbon fiber coating agent is impregnated in carbon fiber and coated on the carbon fiber surface when molding the carbon fiber reinforced composite material, thereby increasing the bonding force between the carbon fiber and the matrix resin to improve the impact strength of the carbon fiber reinforced composite material.

At this time, the general carbon fiber is impregnated with a sizing agent of an epoxy-based material, and when an epoxy resin is used as the base resin of the carbon fiber coating agent, it has high compatibility with the sizing agent, so the carbon fiber coating agent is impregnated in the carbon fiber. It is preferable to directly coat without removing the sizing agent.

In addition, in order to induce an even coating on the carbon fiber surface, it is preferable to use an epoxy resin diluted in a solvent as the epoxy resin included in the carbon fiber coating agent, and to prevent fire and odor problems in the drying step of the manufacturing method In order to do so, it is more preferable that it is a water-based epoxy resin.

Carbon fiber reinforced composite material (CFRP) according to another aspect of the present invention is impregnated with carbon fibers and carbon fibers coated with a carbon fiber coating agent containing an additive having a functional group reacting with the epoxy resin and ethylene oxide including the above-mentioned ethylene oxide. and matrix resin.

At this time, the carbon fiber coating agent is impregnated in the form of a coating solution dispersed in water by mixing with water when impregnating the carbon fiber, and the carbon fiber bundle is immersed in the coating solution formed by mixing the carbon fiber coating agent with water (distilled water) to coat. have. At this time, in the water-dispersed coating solution in which the carbon fiber coating agent and water are mixed, the solid content of the epoxy resin is preferably 1 to 5 wt% of the total water-dispersed coating solution, and more preferably 2 to 4 wt%. When the solid content of the epoxy resin in the water-dispersed coating solution is less than 1 wt%, the amount of coating on the carbon fiber is very small, so the binder function between the carbon fiber-matrix resin is weakened, and when it exceeds 5 wt%, the carbon fiber coating agent is a carbon fiber Rather than being coated on the surface, a separate third layer is formed between the carbon fiber and the matrix resin, and there is a fear that it may act as a foreign material rather than a binder that bonds the carbon fiber and the matrix resin. At this time, water in the aqueous dispersion coating solution is evaporated through a drying process during the manufacturing method, so that the carbon fiber coating agent is coated on the carbon fiber.

In addition, the carbon fiber coated with the carbon fiber coating agent is preferably 0.9 to 1.2 wt% of the carbon fiber coating agent. When the carbon fiber coating agent is less than 0.9 wt%, the amount of carbon fiber coated is very small, so the binder function between carbon fiber-matrix resin is weakened, and when it exceeds 1.2 wt%, the carbon fiber coating agent is coated on the coating on the carbon fiber surface. Rather than a level, a separate third layer is formed between the carbon fiber and the matrix resin, and there is a fear that it may act as a foreign material rather than a binder for bonding the carbon fiber and the matrix resin.

In one embodiment, the matrix resin constituting the carbon fiber reinforced composite material may be any kind of thermosetting resin and thermoplastic resin, but polyamide resin, polyamide resin and ABS resin, polyethylene resin, polypropylene resin, and polyphenyl It is preferable that at least one or a mixture of two or more of the lensulfide resins is used, and in particular, it is more preferable to use a polyamide resin alone or a mixture of a polyamide resin and an ABS resin in consideration of the melting point. In this case, the polyamide resin further preferably includes at least one of polyamide 6, polyamide 6,6, polyamide 6,10, polyamide 11, polyamide 12, and polyamide 4,6.

In one embodiment, when the mattress resin is a mixture of polyamide resin and ABS resin, at least one of polyamide 6, polyamide 6,6, polyamide 6,10, polyamide 11, polyamide 12 and polyamide 4,6 It is preferable that 5 to 30 parts by weight of the polyacrylonitrile-butadiene-styrene (ABS) resin is mixed with 100 parts by weight of the polyamide resin composed of the above.

In one embodiment, the carbon fiber-reinforced composite material preferably includes 50 to 900 parts by weight of the matrix resin based on 100 parts by weight of the carbon fiber. When the content of the matrix resin is less than 50 parts by weight, there is a disadvantage that the strength expression rate of the composite material is lowered due to insufficient resin impregnation, and when it exceeds 900 parts by weight, the strength reinforcement effect due to carbon fibers is low.

The carbon fibers constituting the carbon fiber-reinforced composite material preferably include at least one of PAN-based carbon fibers, pitch-based carbon fibers, and rayon-based carbon fibers. In addition, the carbon fiber is more preferably a PAN-based carbon fiber having a specific gravity of 1.7 to 1.9. Pitch-based carbon fibers are more complicated and expensive to manufacture than PAN-based carbon fibers, and rayon-based carbon fibers have lower physical properties than pitch-based or PAN-based carbon fibers, so a PAN-based carbon fiber that satisfies both mass productivity and physical properties is preferable.

In addition, the carbon fiber preferably has a specific gravity of 1.7 to 1.9. More preferably, the specific gravity of the carbon fiber is preferably 1.75 to 1.85. When the specific gravity of the carbon fiber is lower than 1.7, there are many voids in the carbon fiber filaments forming the carbon fiber tow, or the compactness of the carbon filament is lowered, and accordingly, the carbon fiber tow consisting of a plurality of these carbon fiber filaments When using the carbon fiber composite material to be molded, it has low compressive strength. In addition, when the specific gravity of the carbon fiber is higher than 1.9, the effect of reducing the weight of the carbon fiber composite material is lowered.

In addition, the number of filaments per tow of the carbon fiber tow is preferably 1,000 to 50,000. When the number of filaments is less than 1,000, there is a disadvantage in that the area ratio per volume is low when manufacturing a large-area carbon fiber composite material and the manufacturing cost increases. There is a disadvantage in that the tensile strength and/or compressive strength of the carbon fiber reinforced composite material is lowered.

The carbon fiber-reinforced composite material according to an embodiment of the present invention is not particularly limited in its form, but when a polyamide resin or a mixture of polyamide resin and ABS resin is used as the matrix resin, the fiber chop is in the matrix resin. It is preferable to apply in the form of dispersed short fiber reinforced plastics or long fiber reinforced pellets for injection such as LFT (Long Fiber Reinforced Thermoplastics), or unidirectional (UD) or fabric prepreg. It is more suitable to form intermediate substrates or composites in the form of fiber-reinforced pellets or unidirectional prepregs (UD tapes). In this way, the carbon fiber reinforced composite material prepared in the form of long fiber reinforced pellets or unidirectional prepreg has excellent mechanical properties, and in particular, compared to the carbon fiber reinforced composite material of the same type to which carbon fiber not coated with a carbon fiber coating agent is applied. Impact strength is improved.

In one embodiment, when the carbon fiber reinforced composite material is in the form of long fiber reinforced pellets, the impact strength of the carbon fiber reinforced composite material measured by the IZOD impact test based on ASTM D 235 is the carbon fiber not coated with the carbon fiber coating agent. It is improved by 4.6 to 13% compared to the carbon fiber reinforced composite material of the same type made with

In one embodiment, when the carbon fiber reinforced composite material is in the form of a unidirectional prepreg, the impact strength of the carbon fiber reinforced composite material measured by the IZOD impact test based on ASTM D 235 is a carbon fiber that is not coated with a carbon fiber coating agent. It is improved by 8 to 24.5% compared to the manufactured carbon fiber reinforced composite material of the same type.

1 is a flowchart illustrating a method of manufacturing a carbon fiber reinforced composite material according to another aspect of the present invention.

Referring to Figure 1, the method of manufacturing a carbon fiber reinforced composite material according to an embodiment of the present invention comprises the steps of preparing a carbon fiber coating agent by mixing an epoxy resin containing ethylene oxide and an additive having a functional group reacting with ethylene oxide ( S101), coating the carbon fiber by immersing the carbon fiber in an aqueous dispersion containing a carbon fiber coating agent (S102), drying the coated carbon fiber (S103), and impregnating the dried carbon fiber in a matrix resin to carbon fiber It includes a step (S104) of manufacturing a reinforced composite material.

In the step of preparing a carbon fiber coating agent by mixing an epoxy resin containing ethylene oxide and an additive having a functional group that reacts with ethylene oxide (S101), the carbon fiber coating agent is prepared by mixing an epoxy resin and a predetermined additive. At this time, the epoxy resin included in the carbon fiber coating agent is preferably a water-based epoxy containing ethylene oxide, and the additive has a fatty acid functional group on one side, and excellent compatibility with or reacts with the ethylene oxide group of the epoxy resin on the other side. It is preferable to have a functional group. In addition, the carbon fiber coating agent is preferably 1 to 7 parts by weight, more preferably 3 to 5 parts by weight, based on 100 parts by weight of the epoxy resin solid content.

Next, in the step (S102) of coating the carbon fiber by immersing the carbon fiber in the water-dispersed coating solution containing the coating agent, the carbon fiber coating solution prepared in step S101 is coated on the carbon fiber. At this time, it is preferable to coat the carbon fiber coating agent by immersing the carbon fiber in the form of a coating solution dispersed in water by mixing the carbon fiber coating agent with water so that the carbon fiber coating agent can be uniformly dispersed and coated on the surface of the carbon fiber. In addition, in the water-dispersed coating solution in which the carbon fiber coating agent and water are mixed, the solid content of the epoxy resin is preferably 1 to 5 wt% of the total water-dispersed coating solution, more preferably 2 to 4 wt%

Next, in the step of drying the coated carbon fiber ( S103 ), moisture is dried in the water-dispersed coating solution immersed in the carbon fiber so that only the carbon fiber coating agent is coated on the carbon fiber. In this case, the drying step is preferably carried out by dividing the second.

The primary drying is preferably performed at 100° C. to 180° C., more preferably at 105° C. to 150° C. for 2 minutes to 5 minutes. If the temperature of the primary drying is less than 100 ℃, moisture removal is impossible, and if it is more than 180 ℃, there is a disadvantage in that the coating solution is scattered and a uniform coating cannot be performed.

The secondary drying is preferably performed for 1 minute to 2 minutes at a temperature of 200°C to 260°C, and more preferably less than 100 seconds at 220°C to 240°C. When the secondary drying temperature is less than 200℃, it is difficult to expect the carbon fiber coating agent to function as a binder of the carbon fiber reinforced composite material because thermal fusion between the sizing agent and the coating agent base resin is impossible. Since a reaction between the epoxy and the additive is induced, and the additive with a relatively low molecular weight is bonded to the epoxy with a high molecular weight, the functional groups are not oriented in the correct direction, and the degree of freedom of the additive may be reduced. In addition, if the drying step is not divided into primary drying and secondary drying, problems due to scattering of the coating solution may occur as described above.

Next, in the step (S104) of manufacturing the carbon fiber reinforced composite material by impregnating the dried carbon fiber in the matrix resin, the carbon fiber, which is dried in step S103 and coated with the carbon fiber coating agent, is impregnated in the matrix resin to make the carbon fiber reinforced composite material. is a manufacturing step. At this time, the matrix resin may be any kind of thermosetting resin and thermoplastic resin, but in the present invention, polyamide resin or a mixture of polyamide resin and ABS resin, polyethylene resin, polypropylene resin, polyphenylene sulfide resin, etc. is suitable In addition, polyamide resin alone or a mixture of polyamide resin and ABS resin is more suitable in consideration of the melting point.

In the method for manufacturing a carbon fiber reinforced composite material according to another aspect of the present invention described with reference to FIG. 1, the content overlapping with the carbon fiber reinforced composite material described above was not described as overlapping, but the configuration of the carbon fiber reinforced composite material described above is Of course, it can also be applied to the manufacturing method of the carbon fiber reinforced composite material.

Hereinafter, the configuration of the present invention and its effects will be described in more detail through Examples and Comparative Examples. However, these examples are for explaining the present invention in more detail, and the scope of the present invention is not limited to these examples.

[Example]

[Example 1]

1-1. Manufacture of carbon fiber coating agent and water-dispersed coating solution

First, a carbon fiber coating agent and a coating solution dispersed in water using the same were prepared in the following order.

For the base resin, 100 parts by weight of KWER-828 (Kumho P&B Chemical), a water-based epoxy, is applied, and 5 parts by weight of an adhesion enhancer having a fatty acid as an additive (BYK-4510, BYK Korea) based on 100 parts by weight of the water-based epoxy solid content is added. to prepare a carbon fiber coating agent.

Next, in order to match the amount of carbon fiber coating agent to be coated on carbon fiber, distilled water was added so that the solid content of water-based epoxy was 3 wt%, and stirred at room temperature for 12 hours using a magnetic stirrer to prepare 5 L of a water-dispersed coating solution.

1-2. coating process

The water-dispersed coating solution prepared in step 1-1 was put into the impregnation tank, and the sand road (running conditions of fibers in the process) was configured so that carbon fibers (T700SC-50C-24k of Toray Advanced Materials) were immersed in the impregnation tank. The carbon fiber was immersed through an impregnation roll with a diameter of 260 mm, and the impregnation roll was maintained to be immersed in the coating solution by 100 mm or more from the bottom at all times. After passing through the impregnation tank, the carbon fibers were first dried at 130° C. for 2 minutes to evaporate most of the moisture. Thereafter, the secondary drying was performed by staying in an oven heated to 230° C. for 90 seconds. Next, the carbon fiber after the coating process was wound with a winder for carbon fiber to prepare a carbon fiber coated with a carbon fiber coating agent.

1-3. Manufacture of carbon fiber reinforced composites

A carbon fiber-reinforced composite material was prepared by passing one bundle of carbon fibers obtained through 1-2 through an impregnation tank in which the matrix resin was melted. The matrix resin used at this time was polyamide 6 (Kolon Plastics), and the matrix resin was made to contain 900 parts by weight based on 100 parts by weight of carbon fibers, and the temperature was maintained at 270° C. to prepare a carbon fiber reinforced composite material. At this time, two different types of carbon fiber reinforced composite materials, LFT (long fiber reinforced pellet) and UD tape (unidirectional prepreg), respectively, depending on the mold through which the carbon fiber impregnated with the matrix resin exits from the impregnation tank prepared.

For LFT, a mold having a diameter of 3.5 mm was applied, and the resin content (RC) was 80% by weight with respect to one bundle of 24k carbon fibers, and then processed into pellets of 12 mm in length.

In addition, for the UD tape, a slit-shaped mold with a width of 22 mm and a thickness of 0.5 mm was applied, and the resin content (RC) was set to 50% by weight.

[Example 2]

A carbon fiber reinforced composite material was prepared in the same manner as in Example 1, except that KWER-834 (Kumho P&B Chemical) was applied as a water-based epoxy.

[Example 3]

A carbon fiber reinforced composite material was prepared in the same manner as in Example 1, except that a wetting and dispersing agent (DISPERBYK-192, BYK Korea) having a fatty acid as an additive was applied.

[Example 4]

A carbon fiber reinforced composite material was prepared in the same manner as in Example 3, except that KWER-834 (Kumho P&B Chemical) was applied as a water-based epoxy.

[Example 5]

A carbon fiber reinforced composite material was prepared in the same manner as in Example 1, except that a wetting and dispersing agent (DISPERBYK-2096, BYK Korea) having a fatty acid as an additive was applied.

[Example 6]

A carbon fiber reinforced composite material was prepared in the same manner as in Example 5, except that KWER-834 (Kumho P&B Chemical) was applied as a water-based epoxy.

[Example 7]

A carbon fiber-reinforced composite material was prepared in the same manner as in Example 1, except that 2 parts by weight of an adhesion promoter (BYK-4510) having a fatty acid as an additive and 3 parts by weight of a wetting and dispersing agent (DISPERBYK-192) having a fatty acid were added.

[Example 8]

A carbon fiber-reinforced composite material was prepared in the same manner as in Example 1, except that 3 parts by weight of an adhesion promoter (BYK-4510) having a fatty acid as an additive and 2 parts by weight of a wetting and dispersing agent (DISPERBYK-192) having a fatty acid were added.

[Example 9]

A carbon fiber-reinforced composite material was prepared in the same manner as in Example 1, except that 2 parts by weight of an adhesion promoter (BYK-4510) having a fatty acid as an additive and 3 parts by weight of a wetting and dispersing agent (DISPERBYK-2096) having a fatty acid were added.

[Example 10]

A carbon fiber-reinforced composite material was prepared in the same manner as in Example 1, except that 3 parts by weight of an adhesion promoter (BYK-4510) having a fatty acid as an additive and 2 parts by weight of a wetting and dispersing agent (DISPERBYK-2096) having a fatty acid were added.

[Example 11]

A carbon fiber reinforced composite material was prepared in the same manner as in Example 1, except that 2 parts by weight of a wetting and dispersing agent having a fatty acid (DISPERBYK-192) and 3 parts by weight of a wetting and dispersing agent having a fatty acid (DISPERBYK-2096) were added as additives.

[Example 12]

A carbon fiber reinforced composite material was prepared in the same manner as in Example 1, except that 3 parts by weight of a wetting and dispersing agent having a fatty acid (DISPERBYK-192) and 2 parts by weight of a wetting and dispersing agent having a fatty acid (DISPERBYK-2096) were added as additives.

[Example 13]

A carbon fiber-reinforced composite material was prepared in the same manner as in Example 1, except that 1 part by weight of an adhesion promoter (BYK-4510) having a fatty acid as an additive was added with respect to 100 parts by weight of a water-based epoxy solid content.

[Example 14]

A carbon fiber-reinforced composite material was prepared in the same manner as in Example 1, except that 7 parts by weight of an adhesion promoter (BYK-4510) having a fatty acid as an additive was added based on 100 parts by weight of a water-based epoxy solid content.

[Comparative example]

[Comparative Example 1]

Carbon fiber-reinforced composite material of the same specification as Example 1 without a coating process of carbon fiber coating agent using T700-50C-24k carbon fiber produced by Toray Advanced Materials was prepared.

[Comparative Example 2]

A carbon fiber-reinforced composite material was prepared in the same manner as in Example 1, except that no additives were applied.

[Comparative Example 3]

A carbon fiber reinforced composite material was prepared in the same manner as in Example 2, except that no additives were applied.

[Comparative Example 4]

A carbon fiber-reinforced composite material was prepared in the same manner as in Example 1, except that 0.5 parts by weight of an adhesion promoter (BYK-4510) having a fatty acid as an additive was added based on 100 parts by weight of a water-based epoxy solid content.

[Comparative Example 5]

A carbon fiber-reinforced composite material was prepared in the same manner as in Example 1, except that 8 parts by weight of an adhesion promoter (BYK-4510) having a fatty acid as an additive was added based on 100 parts by weight of a water-based epoxy solid content.

[Comparative Example 6]

A carbon fiber-reinforced composite material was prepared in the same manner as in Example 1 except that a silane-based adhesion enhancer (BYK C8000) was used as an additive.

The physical properties of the carbon fiber coating agents prepared in Examples 1 to 14 and Comparative Examples 1 to 6 according to the present invention and the carbon fiber coating agent adhesion amount after the coating process are shown in Table 1, and the physical properties of CFRPs prepared according to Examples and Comparative Examples is shown in Table 2.

[Experimental example]

(1) Measurement of solid content of water-dispersed coating solution

50 g each of the dispersed coating solution was placed in three vials, and after the moisture was completely dried, the solid content was measured through Equation 1 below. The number of measurements was 5 times, and the average value was determined as the solid content of the water-dispersed coating solution.

(Equation 1)

: 빈 바이알의 질량

: mass of empty vial

: 수분산된 코팅액을 포함한 바이알의 질량

: The mass of the vial including the water-dispersed coating solution

: 수분 증발 후 바이알의 질량

: Mass of vial after water evaporation

: 수분산된 코팅액의 고형분 함량

: Solid content of water-dispersed coating solution

(2) Measurement of sizing agent and carbon fiber coating agent content

The carbon fibers used in Examples and Comparative Examples were put into an electric furnace heated to 450° C. and heat-treated for 15 minutes to remove the sizing agent and coating agent components except for the carbon fibers. At this time, the carbon fiber was prepared at a level of 2 to 3 g, and the number of specimens was 20 per condition. The inside of the electric furnace was purged with nitrogen (N ₂ ) atmosphere, and the amount of sizing agent and carbon fiber coating agent attached was calculated through Equation 2 below.

(Equation 2)

: 열처리 전, 사이징제 및 코팅제를 포함하는 탄소섬유의 질량

: Weight of carbon fiber including sizing agent and coating agent before heat treatment

: 열처리 후, 사이징제 및 코팅제가 제거된 탄소섬유의 질량

: Weight of carbon fiber from which sizing agent and coating agent are removed after heat treatment

: 탄소섬유의 사이징제 및 코팅제 부착량

: Amount of carbon fiber sizing agent and coating agent

In addition, the content of the carbon fiber coating agent by subtracting the sizing agent adhesion amount of T700SC-24k-50C of Toray Advanced Materials calculated in Comparative Example 1 from the sizing agent and coating agent adhesion amount (Sz (%)) of the carbon fiber calculated through Equation 2 was measured.

(3) FT-IR analysis of carbon fiber coatings

In order to confirm the characteristics of the carbon fiber coating agent, FT-IR analysis was performed before and after the reaction of the coating agent. The FT-IR instrument was equipped with Bruker's equipment. The sample before the reaction was obtained by freeze-drying the aqueous dispersion coating solution used in Examples and Comparative Examples, and the sample after the reaction was prepared by heat-treating the freeze-dried sample in an oven at 230° C. for 30 minutes. When measuring FT-IR, the increase rate of the peak near 3,420 cm ^-1 , 1,730 cm ^-1 , 1,000 cm ^-1 ,940 cm ^-1 where the reaction between the water-based epoxy and the additive is expected before and after heat treatment was confirmed.

(4) Evaluation of physical properties of LFT form

The carbon fiber reinforced composite materials obtained in Examples 1 to 14 and Comparative Examples 1 to 6 were injection molded to evaluate tensile, flexural and impact resistance properties of the carbon fiber reinforced composite material specimens.

Tensile properties were evaluated according to ASTM D 638 using Instron Model 5985 UTM and a load cell with a maximum load of 100 kN, and for flexural properties, INSTRON Model 5965 UTM and a load cell with a maximum load of 5 kN according to ASTM D 790 were evaluated. was evaluated, and the impact resistance was evaluated using a CEAST MODEL 6898 impact strength tester and a 0.5J hammer according to ASTM D 256 standard.

In addition, the carbon fiber content of the specimen was measured for normalization after evaluation, and the specimen was burned in an electric furnace heated to 500° C. for 50 minutes, and the carbon fiber content in the specimen was measured through Equation 3 below.

(Equation 3)

: 측정에 사용한 도가니

: Crucible used for measurement

: 연소 전, 탄소섬유 강화 복합재료를 포함한 도가니

: Before combustion, crucible containing carbon fiber reinforced composite material

: 연소 후 잔여물을 포함한 도가니

: Crucible containing residues after combustion

: 탄소섬유 강화 복합재료에 포함된 탄소섬유의 함유량

: Content of carbon fiber in carbon fiber reinforced composite material

(5) Evaluation of physical properties in the form of UD tape

The tensile, flexural, and impact resistance properties of the carbon fiber reinforced composite materials in the form of UD tapes (unidirectional prepregs) obtained in Examples 1 to 14 and Comparative Examples 1 to 6 were evaluated.

Tensile properties were evaluated according to ASTM D 3039 using Instron Model 5985 UTM and a load cell with a maximum load of 100 kN, and flexural properties were evaluated using an INSTRON Model 5965 UTM with a load cell with a maximum load of 5 kN according to ASTM D 790 standards. was evaluated, and the impact resistance was evaluated using a CEAST MODEL 6898 impact strength tester and a 22.6 J hammer according to ASTM D 256 standard.

In addition, the carbon fiber content of the specimen was measured for normalization after evaluation, and the carbon fiber content in the specimen was measured by burning the specimen in an electric furnace heated to 500° C. for 50 minutes. Tests and calculations were performed in the same manner as in Experimental Example 4 described above.

Coating composition components (solids weight ratio) coating solution
solid content
Concentration (wt%) FT-IR peak increase before and after reaction (before/after) after coating
Coating content
(wt%) water based epoxy additive KWER-828 KWER-834 BYK-4510 DISPERBYK-192 DISPERBYK-2096 3420 cm ^-1 1730 cm ^-1 1000 cm ^-1 940 cm ^-1 Example 1 100 - 5 - - 2.9 4.1 2.6 2.1 2.5 1.2 Example 2 - 100 5 - - 3.0 4.0 2.6 2.1 2.4 1.1 Example 3 100 - - 5 - 3.0 2.9 2.7 1.2 1.4 1.1 Example 4 - 100 - 5 - 3.1 3.0 2.6 1.2 1.4 1.0 Example 5 100 - - - 5 3.0 4.8 4.2 2.0 2.5 0.9 Example 6 - 100 - - 5 3.0 4.9 4.1 2.1 2.3 1.2 Example 7 100 - 2 3 - 3.2 3.3 2.6 2.0 2.0 0.9 Example 8 100 - 3 2 - 3.0 3.5 2.5 1.6 2.0 1.0 Example 9 100 - 2 - 3 3.0 4.3 3.3 2.0 2.4 1.1 Example 10 100 - 3 - 2 3.0 4.7 3.8 2.0 2.4 1.0 Example 11 100 - - 2 3 3.2 4.2 3.1 1.7 2.1 1.2 Example 12 100 - - 3 2 3.2 4.0 3.1 1.7 2.0 1.2 Example 13 100 - One - - 3.0 3.6 2.3 1.1 1.3 1.1 Example 14 100 - 7 - - 3.0 4.2 2.7 2.1 2.7 1.2 Comparative Example 1 - - - - - - - - - - - Comparative Example 2 100 - - - - 2.9 - - - - 0.7 Comparative Example 3 - 100 - - - 2.9 - - - - 0.8 Comparative Example 4 100 - 0.5 - - 2.8 3.4 2.1 1.9 2.3 1.0 Comparative Example 5 100 - 8 - - 3.0 4.4 2.9 2.4 3.1 1.0 Comparative Example 6 100 BYK-C8000 5 parts by weight 3.0 5.6 2.5 2.4 3.8 1.8

As can be seen from Table 1 above, in the case of the carbon fiber coating agents of Examples 1 to 14, it can be confirmed that the content of the coating agent is slightly higher than that of Comparative Examples 2 and 3, which is because the wettability is increased due to the additive. .

It was confirmed that the carbon fiber coating agents obtained from Examples 1 to 14 had a reaction between the water-based epoxy and the additive during heat treatment at 230° C. for 30 minutes in common, which was confirmed as a result of FT-IR analysis.

In Examples 1 to 14, the peak increase rate in the vicinity of 3,420 cm ^-1 is 2.5 to 5 times, the peak increase rate in the vicinity of 1,730 cm ^-1 is 2.3 to 5 times, and the peak in the vicinity of 1,000 cm ^-1 is 230 ° C., when heat treatment for 30 minutes or more. It was confirmed that the increase rate was 1.1 to 2.1 times, and the peak increase rate near 940 cm ^-1 was 1.2 to 3 times. you will know

In the present specification, some of the results of comparing the FT-IR before and after the reaction of the carbon fiber coating agent according to Examples 1 to 14 are attached. For example, FIG. 2 is a comparison result of FT-IR before and after the reaction of the carbon fiber coating agent according to Example 1, and FIG. 3 is a comparison result of FT-IR before and after the reaction of the carbon fiber coating agent according to Example 3 and FIG. 4 is a comparison result of FT-IR before and after the reaction of the carbon fiber coating agent according to Example 5. Here, the FT-IR result is a characteristic of the carbon fiber coating agent itself.

As can be seen from this, it can be seen that the additives used in Examples 1 and 5 have a relatively slow reaction with the water-based epoxy, but the additive used in Example 3 has a fast reaction rate with the water-based epoxy. However, since the reaction between the additive and the water-based epoxy may occur when the heat treatment time is prolonged, in the present invention, it is preferable to limit the heat treatment time at 200° C. or more to less than 120 seconds in order to suppress the reaction between the additive and the water-based epoxy as much as possible. In particular, as shown in FIG. 5 , when the heat treatment time is 2 minutes (120 seconds) or more, it can be confirmed that it is preferable to set the heat treatment time to less than 120 seconds through peak growth compared to the case where the heat treatment time is less than 120 seconds.

In addition, Comparative Example 4 using a small amount of additives has a slight problem in that the effect of increasing the physical properties of the composite material is insignificant, and in Comparative Example 5 using an excessive amount of additives, the FT-IR measurement result is out of the range limited by the present invention, and between the water-based epoxy and the additive. Since the reaction is easy, this also has a problem of inhibiting the increase of the physical properties of the composite material.

In addition, in Comparative Example 6 using a silane-based additive rather than a fatty acid, the FT-IR measurement result was outside the range limited in the present invention, which means that the reaction between the water-based epoxy and the additive was easily made, thereby lowering the water dispersion stability of the coating solution have the problem of making Accordingly, the reactivity between the silane-based additive and the water-based epoxy is high, which leads to a problem that the reactants of the two materials are precipitated in the form of lumps as time goes by, so there is a problem that a uniform coating process is impossible. In addition, when the reactant is attached to the surface of the carbon fiber, it may act as a defect that reduces the physical properties of the composite material.

Long Fiber Reinforced CFRP (LFT) UD Tape Tensile strength (MPa) Seal
Modulus of elasticity (GPa) Flexural strength (MPa) curve
Modulus of elasticity (GPa) Impact strength (kJ/m ² ) Tensile strength (MPa) Seal
Modulus of elasticity (GPa) Flexural strength (MPa) curve
Modulus of elasticity (GPa) Impact strength (kJ/m ² ) Example 1 195.2 15.4 285.6 12.4 13.5 1730.9 88.3 935.8 76.1 282.4 Example 2 195.5 15.4 290.0 12.8 13.6 1730.1 88.3 930.2 78.1 288.1 Example 3 205.8 15.2 288.3 12.2 14.0 1464.7 85.1 1019.7 77.4 296.4 Example 4 206.1 15.3 290.3 12.8 14.5 1484.4 86.2 1022.2 77.9 300.1 Example 5 190.2 15.4 295.0 12.5 14.1 1446.7 82.4 1110.0 77.9 260.2 Example 6 190.2 15.5 299.1 12.6 14.4 1470.1 83.0 1121.2 78.3 271.1 Example 7 201.3 15.3 286.3 12.3 13.7 1610.1 86.4 1004.8 77.1 290.5 Example 8 200.9 15.3 285.3 12.4 13.7 1611.9 86.4 1004.0 77.5 291.1 Example 9 194.8 15.3 290.1 12.4 13.8 1605.5 85.9 1005.5 77.5 274.9 Example 10 195.0 15.2 292.3 12.5 13.7 1604.8 85.5 1010.0 77.9 276.1 Example 11 199.4 15.4 293.3 12.6 14.5 1466.4 83.5 1109.6 78.0 296.1 Example 12 199.4 15.5 293.1 12.6 14.1 1458.8 83.7 1118.1 78.1 299.5 Example 13 192.2 15.4 285.5 12.3 13.4 1725.5 88.3 935.9 77.1 268.2 Example 14 195.2 15.4 289.1 12.4 13.5 1730.1 88.3 934.4 76.2 267.9 Comparative Example 1 206.0 14.7 293.2 12.1 12.8 1400.2 79.5 925.7 66.5 240.9 Comparative Example 2 179.4 13.3 287.7 10.6 10.5 1377.7 73.7 900.1 64.4 233.3 Comparative Example 3 181.1 13.4 291.0 11.0 10.3 1401.1 79.5 915.4 64.9 231.7 Comparative Example 4 182.2 14.4 296.5 11.1 12.9 1650.0 87.7 920.1 75.9 259.2 Comparative Example 5 183.2 14.4 289.8 11.2 12.7 1655.0 88.2 922.2 76.1 255.9 Comparative Example 6 172.1 15.6 266.1 13.5 10.2 1369.9 90.1 814.4 80.1 228.8

As can be seen from Table 1 above, Examples 1 to 14 each applied different water-based epoxies and additives, and it can be confirmed that tensile strength, tensile modulus, flexural strength, and flexural modulus tend to be expressed at equal or higher levels. .

In particular, it can be seen that in all Examples of Examples 1 to 14, the impact strength was improved compared to Comparative Example 1 in which the carbon fiber coating agent was not used. At this time, as compared to Comparative Example 1 in which the carbon fiber coating agent is not used, it can be seen that the increase in the impact strength of Examples 1 to 14 is 4.6 to 13% for LFT, and 8 to 24.5% for UD tape. Therefore, it can be confirmed that the carbon fiber-reinforced composite material according to the present invention has improved interfacial bonding strength between the matrix resin and the carbon fiber. In addition, compared to Comparative Example 6 without a fatty acid by using an additive having a silane-based functional group, the impact strength increase in Examples 1 to 14 was 31 to 42% in the case of LFT, and 13 to 31% in the case of UD tape. it can be confirmed that

On the other hand, Comparative Examples 2 and 3 were coated with only a water-based epoxy without using an additive, and both impact strength and other physical properties were measured to be the same or lower than those of Comparative Example 1.

In addition, it can be seen that Comparative Example 4 using a small amount of additives lacks a binder material between the carbon fiber and the matrix resin, and thus the impact strength is lower than those of Examples 1 to 14.

In addition, in Comparative Example 5 using excessive additives, it was confirmed that the FT-IR peak fluctuation range was larger than that of Examples 1 to 14, indicating that the reaction between the water-based epoxy and the additive was easily made, thereby increasing the physical properties of the composite material. have a hindrance problem.

In addition, in Comparative Example 6 using the additive having a silane-based functional group, the reaction between the water-based epoxy and the additive is easily made, and it can be seen that the impact strength is lower than that of Examples 1 to 14.

The result of measuring the physical properties of the carbon fiber reinforced composite material well indicates that the interfacial bonding force between the matrix resin and the carbon fiber is improved by coating the carbon fiber with the carbon fiber coating agent according to an embodiment of the present invention.

Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims are also provided. is within the scope of the

Claims (19)

an epoxy resin comprising ethylene oxide; and
an additive having a functional group that reacts with the ethylene oxide;
includes,
Fourier transform infrared spectroscopy (FT-IR) measurement results after heat treatment at 230 ° C. or higher for 30 minutes or more show that the peak increase rate near 3,420 cm ^-1 is 2.5 to 5 times, and the peak increase rate near 1,730 cm ^-1 is 2.3 to 5 times, and 1,000 The peak increase rate in the vicinity of cm ^-1 is 1.1 to 2.1 times, and the peak increase rate in the vicinity of 940 cm ^-1 is 1.2 to 3 times, the carbon fiber coating agent. delete According to claim 1,
The additive further comprises a fatty acid that is combined with the matrix resin when molding the carbon fiber reinforced composite material, carbon fiber coating agent. According to claim 1,
A carbon fiber coating agent comprising 1 to 7 parts by weight of the additive based on 100 parts by weight of the solid content of the epoxy resin. Carbon fibers coated with a carbon fiber coating agent comprising an epoxy resin containing ethylene oxide and an additive having a functional group reacting with the ethylene oxide; and
a matrix resin impregnated in the carbon fiber;
includes,
The carbon fiber coating agent has a Fourier Transform Infrared Spectroscopy (FT-IR) measurement result after heat treatment at 230 ° C. or higher for 30 minutes or more, and the peak increase rate in the vicinity of 3,420 cm ^-1 is 2.5 to 5 times, and the peak increase rate in the vicinity of 1,730 cm ^-1 is 2.3. to 5 times, and the peak increase rate in the vicinity of 1,000 cm ^-1 is 1.1 to 2.1 times, and the peak increase rate in the vicinity of 940 cm ^-1 is 1.2 to 3 times, the carbon fiber reinforced composite material. delete 6. The method of claim 5,
The carbon fiber coating agent comprising 1 to 7 parts by weight of the additive based on 100 parts by weight of the solid content of the epoxy resin, carbon fiber reinforced composite material. 6. The method of claim 5,
The additive further comprises a fatty acid combined with the matrix resin when molding the composite material, carbon fiber reinforced composite material. 6. The method of claim 5,
A carbon fiber reinforced composite material comprising 50 to 900 parts by weight of the matrix resin with respect to 100 parts by weight of the carbon fiber. 6. The method of claim 5,
The carbon fiber coated with the carbon fiber coating agent is a carbon fiber reinforced composite material coated with 0.9 to 1.2 wt% of the carbon fiber coating agent. 6. The method of claim 5,
wherein the matrix resin comprises at least one of polyamide 6, polyamide 6,6, polyamide 6,10, polyamide 11, polyamide 12 and polyamide 4,6. 6. The method of claim 5,
The matrix resin is polyacrylonitrile in 100 parts by weight of a polyamide resin including at least one of polyamide 6, polyamide 6,6, polyamide 6,10, polyamide 11, polyamide 12 and polyamide 4,6 -Butadiene-styrene (ABS) resin 5 to 30 parts by weight is mixed, carbon fiber reinforced composite material. 6. The method of claim 5,
When the carbon fiber reinforced composite material is in the form of long fiber reinforced pellets, the impact strength of the carbon fiber reinforced composite material measured by the IZOD impact test based on ASTM D 235 is made of carbon fiber that is not coated with the carbon fiber coating agent A carbon fiber reinforced composite material, which is improved by 4.6 to 13% compared to a carbon fiber reinforced composite material of the same type. 6. The method of claim 5,
When the carbon fiber-reinforced composite material is in the form of a unidirectional prepreg, the impact strength of the carbon fiber-reinforced composite material measured by the IZOD impact test based on ASTM D 235 is made of carbon fiber that is not coated with the carbon fiber coating agent A carbon fiber reinforced composite material, which is improved by 8 to 24.5% compared to the carbon fiber reinforced composite material of the same type. 6. The method of claim 5,
The specific gravity of the carbon fiber is 1.7 to 1.9, carbon fiber reinforced composite material. Preparing a carbon fiber coating agent by mixing an epoxy resin containing ethylene oxide and an additive having a functional group that reacts with ethylene oxide;
coating the carbon fiber by immersing the carbon fiber in the water-dispersed coating solution containing the carbon fiber coating agent;
drying the coated carbon fiber; and
preparing a carbon fiber reinforced composite material by impregnating the dried carbon fiber into a matrix resin;
includes,
The carbon fiber coating agent has a Fourier Transform Infrared Spectroscopy (FT-IR) measurement result after heat treatment at 230 ° C. or higher for 30 minutes or more, and the peak increase rate in the vicinity of 3,420 cm ^-1 is 2.5 to 5 times, and the peak increase rate in the vicinity of 1,730 cm ^-1 is 2.3. to 5 times, the peak increase rate in the vicinity of 1,000 cm ^-1 is 1.1 to 2.1 times, and the peak increase rate in the vicinity of 940 cm ^-1 is 1.2 to 3 times, the method for producing a carbon fiber reinforced composite material. 17. The method of claim 16,
The method for producing a carbon fiber reinforced composite material, wherein the water-dispersed coating solution is 1 to 5% by weight of the total water-dispersed coating solution in the solid content of the epoxy resin. 17. The method of claim 16,
The drying step is
A primary drying step of drying for 2 to 5 minutes at a temperature of 100 ℃ to 180 ℃; and
a secondary drying step of drying at a temperature of 200° C. to 260° C. for 1 to 2 minutes;
A method for producing a carbon fiber reinforced composite material comprising a. 19. The method of claim 18,
The first drying step is a step of drying at a temperature of 105 ° C. to 150 ° C. for 2 to 5 minutes,
The secondary drying step is a step of drying at 220 ° C. to 240 ° C. for less than 100 seconds, a method for producing a carbon fiber reinforced composite material.

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