KR102439573B1 - Manufacturing method of carbon fiber-reinforced Acrylonitrile-Butadiene-Styrene composite by LFT process and long-fiber reinforced Acrylonitrile-Butadiene-Styrene composite manufactured thereby - Google Patents

Abstract

The present invention relates to a manufacturing method of a carbon fiber-reinforced acrylonitrile-butadiene-styrene (ABS) composite by an LFT process, which impregnates carbon fibers with a molten ABS resin through the LFT process by supplying and filling the molten ABS resin from an extruder into a die for resin impregnation, and then supplying the carbon fibers to the die, thereby improving the impregnability between the carbon fibers and the ABS resin and physical properties of the carbon fiber-reinforced ABS composite manufactured by the method.

Description

Manufacturing method of carbon fiber-reinforced ABS composite by LFT process and carbon fiber-reinforced ABS composite manufactured accordingly manufactured thereby}

The present invention relates to a method for manufacturing a carbon fiber reinforced ABS composite material by an LFT process, and by controlling the shape of a die for resin impregnation during the LFT process, the impregnation property of ABS to carbon fiber and interfacial adhesion properties between carbon fiber and ABS resin It relates to a method of manufacturing a carbon fiber reinforced ABS composite by the LFT process to improve the physical properties of the carbon fiber reinforced ABS composite by improving the carbon fiber reinforced ABS composite material.

Carbon fiber reinforced composites (CFRC) are a combination of high-strength carbon fibers as reinforcing fibers in a thermosetting or thermoplastic polymer matrix. It has been widely used as a lightweight material in various fields such as civil engineering/construction, wind turbine blades, military and defense industries, and thermosetting resins have been used for a long time as a matrix resin for carbon fiber reinforced composite materials.

Thermosetting resins not only have excellent mechanical and thermal properties after curing, but also have a very low viscosity before curing and have high impregnation properties for reinforcing fibers. Various types of fibers can be used.

However, since thermosetting resins require a curing reaction, the molding cycle time increases, productivity decreases, and recycling is impossible, so it is difficult to apply them to various material fields.

Therefore, recently, there is no need for curing reaction, so the molding cycle time can be shortened, the productivity is high, and technology development using a recyclable thermoplastic resin is in progress. For example, in the case of ABS resin, which is one of the thermoplastic resins, by varying the chemical composition ratio of acrylonitrile, butadiene, and styrene constituting the ABS resin, thermal stability, chemical resistance, rigidity, aging resistance, toughness, and impact resistance As a material having excellent physical properties such as , low temperature resistance and processibility, it can be used as a matrix of a carbon fiber reinforced composite material. However, this ABS resin has a high melt viscosity and low miscibility with carbon fibers and low impregnation properties for carbon fibers, so carbon fiber-reinforced thermoplastic composites prepared by using them as a matrix are mainly melted and compounded using short fibers or chopped fibers. It was manufactured through extrusion and injection molding processes that go through a compounding step.

However, when a carbon fiber reinforced composite is manufactured by extrusion or injection molding process, the carbon fiber is broken due to the screw action in the extruder, and the length of the carbon fiber is greatly reduced, resulting in a low fiber aspect ratio. In the case of manufacturing, it is difficult to realize high physical properties.

Therefore, long fiber reinforced thermoplastic (LFT) process technology is applied to increase the fiber aspect ratio by preventing the breakage of carbon fibers and to manufacture a fiber-reinforced thermoplastic composite with improved physical properties by compensating for the shortcomings of the thermoplastic resin matrix. do.

The LFT process is a thermoplastic composite material molding technology that uses long fibers (3mm to 25mm) and thermoplastic resin, and combines pultrusion and extrusion technology. The fibers are not damaged, cut, or pulverized during the process, and a relatively long reinforcing fiber state is maintained, thereby increasing the aspect ratio, and thus, the composite material prepared therefrom can exhibit significant improvement in physical properties.

U.S. Patent Publication No. 2013-0113133 (published on May 9, 2013) relates to a method for manufacturing a hybrid structure composite material reinforced with long fibers, wherein a resin for impregnation is injected into a passage through which fiber filaments pass, and long fibers It discloses manufacturing a composite material reinforced with a hybrid structure, and discloses PA, ABS, etc. as the impregnating resin, and discloses carbon fiber as a fiber filament.

However, in the case of the prior literature, the impregnating resin is supplied from a portion away from the fiber filament inlet, and is supplied at an angle of less than 90° with respect to the direction of movement of the filament, so that the resin such as PA or ABS is incomplete in the carbon fiber. There is a limit to being impregnated.

In addition, Korean Patent Application Laid-Open No. 1996-0033683 (published on October 22, 1996) relates to a method for manufacturing a long fiber reinforced thermoplastic composite material, wherein a molten resin is supplied from an extruder to a crosshead, and reinforcing fibers are used as the crosshead. After passing the roving to coat the fiber roving with a resin, moving it to an impregnation die to impregnate the resin applied to the roving between the fibers of the roving, manufacturing a long fiber reinforced thermoplastic composite material. have.

However, in the case of the prior literature, the reinforcing fiber roving supplied to the crosshead must be preheated before feeding to the crosshead, and furthermore, the reinforcing fiber roving is not impregnated with the molten resin in the crosshead, but is primarily reinforced at the crosshead. After the resin is coated on the fiber roving, it is moved to an impregnation die, and the resin applied to the roving in the impregnation die is impregnated between the fibers of the roving, thereby reducing process efficiency and productivity.

Long fiber reinforced thermoplastic composites using this LFT process affect not only the fiber composition, fiber length, fiber orientation, and matrix properties, but also the interfacial adhesion between the fibers and the matrix, and physical properties depending on the manufacturing method.

As an example, in pultrusion molding of fiber-reinforced thermoplastic prepreg materials (Composites Part B 89 / p.328-339 (2016), Daekyung Seo), a cross-head extrusion die is used when manufacturing a thermoplastic matrix prepreg product, but the cross - Disclosed is the production of prepregs by feeding the resin in a direction perpendicular to the fibers passing through the head extrusion die.

However, when the prepreg is manufactured by extruding the resin in a direction perpendicular to the fiber in the cross-head die, the permeability of the resin to the fiber is insufficient, so there is a limit in improving the physical properties of the composite material.

Therefore, the present invention is to improve the problems of the conventional carbon fiber reinforced composite material manufacturing by LFT, to prevent damage to the fiber, and to significantly improve the impregnation property of the resin to the fiber, carbon fiber reinforced by LFT to improve the physical properties of the composite material However, an invention in which an ABS resin impregnation method for carbon fiber during the LFT process is different is provided for preparing an ABS composite material.

US Patent Publication No. 2013-0113133 (published date: 2013.05.09) Korean Patent Publication No. 1996-0033683 (published date: October 22, 1996)

Pultrusion molding of fiber-reinforced thermoplastic prepreg materials (Composites Part B 89 / p.328-339 (2016), Daekyung Seo)

The present invention improves the impregnation property of the ABS resin to the carbon fiber by controlling the shape of the die for resin impregnation of the LFT process in the production of the carbon fiber reinforced ABS composite material by the LFT process, and through this, the carbon fiber and the ABS resin The first task is to provide a method for manufacturing a carbon fiber reinforced ABS composite material by the LFT process that improves physical properties such as interfacial adhesive properties, tensile strength, flexural modulus, and impact strength.

In addition, the present invention makes a second solution to provide a carbon fiber reinforced ABS composite material manufactured by the manufacturing method of the carbon fiber reinforced ABS composite material by the LFT process.

The present invention in order to solve the above problems, in the manufacturing method of the carbon fiber reinforced ABS composite material by the LFT process, (a) by extruding the molten ABS resin from the extruder to a resin impregnation die, inside the resin impregnation die Filling the with molten ABS resin; (b) drawing carbon fibers from one end of the resin impregnation die filled with the molten ABS resin to the other end to prepare a towpreg impregnated with the molten ABS resin; and (c) cooling the towpreg impregnated with the molten ABS resin to prepare a solid towpreg;

In one embodiment, before cooling the towpreg impregnated with the ABS resin melted in step (c), the method may further include pressing.

In one embodiment, the resin impregnation die may be a crosshead-die in which the molten ABS resin and the carbon fiber move together in the same horizontal direction and the carbon fiber is impregnated with the molten ABS resin. have.

The present invention provides a carbon fiber-reinforced ABS composite manufactured by a method for manufacturing a carbon fiber-reinforced ABS composite by the LFT process in order to solve the other problems described above.

In one embodiment, the carbon fiber reinforced ABS composite material includes carbon fiber and ABS (Acrylonitrile-Butadiene-Styrene copolymer) resin, the tensile strength is 60 to 80 MPa, the tensile modulus is 9.0 to 15 GPa, and the flexural strength is 100 to 130 MPa, and may have a flexural modulus of 17.5 to 30 GPa.

After filling the molten ABS resin in the resin impregnation die according to the present invention, when carbon fibers are passed through the resin impregnation die to produce a carbon fiber reinforced ABS composite, the carbon fibers are evenly distributed between the ABS resin matrix As a result, interfacial adhesion properties are improved, and there is no resin-impregnated carbon area or the range of the area is significantly reduced, so physical properties such as tensile strength, flexural strength, and flexural modulus are improved.

Figure 1 (a) shows a T-type type of resin impregnation die of the LFT process according to an embodiment of the present invention and a towpreg manufacturing process according thereto, Figure 1 (b) is an embodiment of the present invention It shows a die for resin impregnation of the I-type type of the LFT process and the towpreg manufacturing process accordingly.
Figure 2 (a) shows the manufacturing of the towpreg according to the T-type resin impregnation die of the LFT process according to an embodiment of the present invention and a process for pressing the same, and Figure 2 (b) is the present invention. It shows the manufacturing of the towpreg according to the I-type resin impregnation die of the LFT process according to an embodiment and the process of pressing the same.
3 is a view showing an injection molding process according to an embodiment of the present invention.
4 is a graph showing (a) tensile strength and (b) tensile modulus of carbon fiber/ABS composite material injection-molded according to an embodiment of the present invention.
5 is a graph showing (a) flexural strength and (b) flexural modulus of an injection-molded carbon fiber/ABS composite material according to an embodiment of the present invention.

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 general, the nomenclature used herein is those well known and commonly used in the art.

In the present specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

1 (b) is a view showing the shape of the resin impregnation die of the LFT process according to an embodiment of the present invention and the manufacturing process of the carbon fiber reinforced ABS composite material according thereto, and the present invention will be described in detail with reference to this.

In one aspect, the present invention, in a method for manufacturing a carbon fiber reinforced ABS composite by an LFT process, (a) extruding the molten ABS resin from the extruder to a resin impregnation die, and the inside of the resin impregnation die is molten ABS filling with resin; (b) drawing carbon fibers from one end of the resin impregnation die filled with the molten ABS resin to the other end to prepare a towpreg impregnated with the molten ABS resin; and (c) cooling the towpreg impregnated with the molten ABS resin to prepare a solid towpreg;

In the present invention, in the step (a), the ABS resin is put into the hopper of the extruder and melted, and then the molten ABS resin is supplied to the resin impregnation die connected to the extruder head to measure the entire inner length of the resin impregnation die. It is a step of filling with the molten ABS resin.

The ABS resin is a polymer in which three components of acrylonitrile (A), butadiene (B) and styrene (S) are connected as repeating units. It has a chain-grafted terpolymer structure, and can generally be prepared through bulk polymerization, emulsion polymerization, or bulk-suspension polymerization.

The properties of the ABS resin may vary depending on the chemical composition ratio of acrylonitrile, butadiene, and styrene constituting the ABS resin. That is, acrylonitrile is composed of a vinyl group to which nitrile is bonded, and has properties such as thermal stability, chemical resistance, rigidity, and aging resistance. is connected to each other by a single bond to form a repeating unit, so it has toughness, impact resistance, and low-temperature resistance. processibility), in the case of ABS resins in which they are combined, properties may vary depending on their chemical composition ratio.

Therefore, the ABS may vary the content of each of the components according to the use and required characteristics, and preferably contains about 15 to 35% of acrylonitrile, about 5 to 30% of butadiene, and about 40 to 60% of styrene can do.

In the present invention, the step (b) is a step of manufacturing a towpreg impregnated with the molten ABS resin by drawing carbon fibers from one end to the other end of the resin impregnation die filled with the molten ABS resin.

Specifically, in step (b), the carbon fiber is supplied to one end of the resin impregnation die filled with the molten ABS resin, so that the carbon fiber is in contact with the molten ABS resin over the entire section of the resin impregnation die. It moves so that it is drawn to the other end of the resin impregnation die. Accordingly, the contact time and contact area between the carbon fiber and the molten ABS resin in the resin impregnation die are increased, so that the environment in which the molten ABS resin can penetrate the carbon fiber continues for a long time, and the molten ABS A towpreg with improved resin impregnation property is prepared.

This resin impregnation die is a crosshead-die mounted vertically with respect to the extruder, and the directions of the inlet and outlet of the molten ABS resin into the resin impregnation die are different, but the resin impregnation The direction of movement toward the discharge part of the molten ABS resin in the die and the carbon fiber passing through it is the same.

Specifically, as shown in FIG. 1(b), the molten ABS resin is supplied to a resin impregnation die connected to an extruder, that is, a crosshead-die, and the entire length of the crosshead-die is molten ABS resin and the carbon fiber enters the resin impregnation die filled with the molten ABS resin and is drawn toward the discharge part together in the same horizontal direction as the molten ABS resin, so that the ABS resin molten in the carbon fiber is The impregnated and impregnated, towpregs are prepared.

The _towpreg produced by the above process and discharged from the resin impregnation die is in a somewhat flexible state, and as shown in FIG. It is possible to further improve the impregnability and interfacial adhesion properties of the molten ABS resin to the fiber.

In step (b), the carbon fibers are continuously supplied to the resin impregnation die and are tows made of untwisted continuous filament bundles. The tow size is not limited, but may be 1K to 60K, preferably 1K to 24K, where 'K' represents the number of filaments in the carbon fiber tow, and 1K tow is made of 1,000 thin fiber filaments. it means.

In addition, the carbon fiber may be a PAN (polyacrylonitrile)-based, pitch-based or rayon-based carbon fiber, preferably a PAN-based carbon fiber.

In the present invention, step (c) is a step of preparing a solid towpreg by cooling the towpreg impregnated with the molten ABS resin. Since the above process is carried out by the generally known LFT process, it is not specifically described, and the LFT series of processes (a) to (c) are for continuous supply of carbon fiber and molten ABS resin by extrusion and drawing. The tow pregs produced in this way may be stored in a bobbin so as not to be entangled with each other, or may be cut and manufactured in the form of pellets.

The pellets prepared according to the present invention contain 20 to 45% by weight of carbon fibers based on the total weight of the pellets. When the carbon fiber content is less than 20% by weight, it cannot be expected to sufficiently improve the properties of the carbon fiber-reinforced ABS composite material. Alternatively, it may act as an impurity to impair the physical properties of the carbon fiber reinforced ABS composite. Therefore, in the pellet, the carbon fiber is included in an amount of 20 to 45% by weight, preferably 25 to 35% by weight.

In addition, the aspect ratio of the pellets is 3 to 20. When the aspect ratio of the pellets is less than 3, the length of the pellets is too short, so it is difficult to effectively increase the mechanical properties in the composite. There may be problems limiting the effectiveness.

Therefore, preferably, the aspect ratio of the pellets is 5 to 15.

In addition, the pellet may be molded by injection molding or compression, and the towpreg cutting, pellet manufacturing, injection molding or compression may be performed by a generally known process, so the process is not specifically described.

The carbon fiber-reinforced ABS composite material prepared according to this method includes carbon fiber and ABS (Acrylonitrile-Butadiene-Styrene copolymer) resin, and has a tensile strength of 60 to 80 MPa, a tensile modulus of 9.0 to 15 GPa, and a flexural strength is 100 to 130 MPa, and may have a flexural modulus of 17.5 to 30 GPa.

The carbon fiber-reinforced ABS composite material is prepared by using a crosshead-die in the LFT process according to the above method to prepare a resin-impregnated towpreg, but the crosshead-die is first filled with a molten ABS resin, and then the crosshead -A tow preg is produced by passing carbon fibers through a die, improving the impregnation property of ABS resin to carbon fibers.

Accordingly, the carbon fiber-reinforced ABS composite material does not have a carbon region that is not impregnated with ABS resin or has a small region range, and carbon fibers are evenly distributed between the ABS resin matrix, thereby interfacial adhesion of carbon fibers and ABS resin. characteristics are improved. Therefore, when a load is applied from the outside, the carbon fiber-reinforced ABS composite material receives a relatively smaller load than the initially applied load as the load is uniformly transmitted to the neighboring carbon fiber and the resin matrix, resulting in tensile strength, tensile modulus of elasticity, flexural strength , the flexural modulus is improved.

Hereinafter, the present invention will be described in more detail by way of Examples, but the present invention is not limited by the Examples.

<Example>

ingredient

(1) carbon fiber

The PAN-based carbon fiber (carbon fiber, 12K, T700 grade) used as the reinforcing fiber of the carbon fiber-reinforced ABS composite is manufactured by Toray Advanced Materials (Korea), and has a density of 1.8 g/cm ³ , The tensile strength was about 4,900 MPa and the tensile modulus was about 230 GPa, and it was supplied in the form of a continuous fiber wound on a cylindrical bobbin for the LFT process.

(2) Matrix resin - ABS resin

The ABS resin used as the matrix of the carbon fiber-reinforced ABS composite material is a pellet-shaped ABS780F model purchased from Kumho Petrochemical (Korea) and has ultra-high flow properties, and the ABS780F has 20-30% acrylonitrile, 10-30% butadiene. % and 50 to 65% of styrene. In addition, the density of ABS780F is 1.04 g/cm ³ , the melt flow index (270℃, 5 kg) is 72.5 g/10 min, the tensile strength is about 42 MPa, the flexural strength is about 60 MPa, The flexural modulus is about 2,100 MPa, the Izod impact strength is about 15 kJ/m ² , and the heat deflection temperature (HDT) is about 82°C.

LFT pellet manufacturing

A lab-scale LFT device that combines a single-screw extruder (Ø20) and a pulling machine manufactured by Bautek (Korea) was used to manufacture the resin-impregnated carbon fiber towpreg. LFT pellet production using this is carried out by the following LFT pellet manufacturing method, I-type, MI-type, T according to the resin type impregnated in the carbon fiber according to the die shape through which the carbon fiber tow passes. -type and MT-type were prepared, respectively.

(LFT pellet manufacturing method)

In LFT pellet manufacturing, a continuous carbon fiber tow in the form of a bobbin passes through a die connected to the extruder head according to the LFT process, and the ABS pellets fed through the hopper of the extruder are melted inside the extruder and the die connected to the extruder by screw rotation The molten resin was impregnated into a continuous carbon fiber tow that was extruded into a furnace and passed through a die connected to the extruder head.

The resin-impregnated towpreg was cooled through a water bath while being pulled by a drawing machine. The towpreg thus prepared was wound and stored on a cylindrical bobbin so as not to become entangled with each other.

The towpreg was cut to a length of 12 mm using a pelletizer developed by ACE C&TECH (Korea) to prepare LFT pellets.

The carbon fiber content compared to the resin was calculated by dividing the weight of the carbon fiber tow of 10 cm length by the weight of the carbon fiber of the same length impregnated with the resin and then multiplying by 100%.

In addition, in order to remove the effect of moisture in the LFT pellet manufacturing process, ABS pellets and carbon fiber bobbins dried for 12 hours in a drying oven at 80 ° C were used respectively, and the screw rotation speed of the extruder and the speed of the drawing machine were adjusted by controlling the LFT Pellets were prepared.

(1) I-type and MI-type LFT pellets

However, in the process of impregnating the molten resin in the continuous carbon fiber tow, as shown in FIG. 1(b), the LFT pellets are prepared according to the LFT process, after filling with the molten ABS resin extruded by the cross-die , By supplying continuous carbon fiber to the cross-die, the carbon fiber and the molten ABS resin in the cross-die horizontally moved in the same direction to produce a towpreg impregnated with the molten ABS resin in the carbon fiber tow. , the pellets thus prepared were named I-type.

In addition, as shown in FIG. 2(b), the LFT pellets prepared by further including the step of pressing the prepared towpreg before cooling were named MI-type.

(2) T-type

According to the LFT process, LFT pellets are prepared, but as shown in FIG. 1(a), the molten resin is passed through an extruder head connected to a cross-die, perpendicular to the carbon fiber tow passing through the cross-die. A towpreg was prepared in which the carbon fiber tow was impregnated with a molten resin by extruding it in a round shape in the phosphor direction. The pellets thus prepared were named T-type.

In addition, the pellets prepared by pressing the prepared towpreg as shown in FIG. 2(a) before entering the cooling water bath were named MT-type.

In the preparation of the T-type and I-type LFT pellets, the LFT process conditions and the carbon fiber content of the LFT pellets prepared accordingly are shown in Table 1 below.

Barrel Temperature (℃) Thermoplastic Resin Zone 1 Zone 2 Head Die ABS 160 210 270 270 Thermoplastic Resin Cross-die type screw speed
(rpm) pulling speed
(rpm) carbon fiber
(wt%) ABS T-type 7.0 4.1 30-33 I-type 5.2 3.8

Manufacture of injection molded carbon fiber/ABS composite material

The carbon fiber/ABS LFT pellets of each pellet type (T-type, I-type, MT-type and MI-type) prepared above were subjected to an injection molding process to prepare a carbon fiber/ABS composite material according to each pellet type. .

Before performing the injection molding process, each type of LFT pellets were dried in a drying oven at 80° C. for 12 hours to remove the effect of moisture. The injection molding process was performed using an injection molding machine (PRO-WD 80) manufactured by Dongshin Hydraulics (Korea), and injection molding was performed according to the conditions shown in FIG. 3 and Table 2 below.

In addition, the composite material according to each pellet type manufactured by the injection molding process was prepared in the form of a specimen for performing the following characteristic analysis.

Table 2 below shows the injection molding conditions of the carbon fiber/ABS composite material by the carbon fiber/ABS LFT pellet, and was made by the injection molding machine of FIG.

Barrel Temperature (℃) Mold Temperature (℃) Cooling time (s) zone 1 zone 2 zone 3 Nozzle 80 20 270 260 250 270 Molding Process conditions Parameter Injection 1 Injection 2 Injection 3 Injection 4 Injection 5 holding
Pressure1 holding
Pressure2 holding
Pressure3 Pressure
(kg/cm2) 28 28 30 38 38 20 20 20 Speed (%) 35 30 30 30 30 25 Time(s) 2.0 2.0 2.0 4.0 4.0 5.0 3.0 1.0 Position
(mm) 48.0 38.0 23.0 21.0 18.0

Characterization

(1) Tensile test

4 shows the results of (a) tensile strength and (b) tensile modulus of carbon fiber/ABS composite material manufactured through the injection molding process. The tensile strength and tensile modulus were tested by the following method.

(Tensile strength and tensile modulus test method)

The tensile test of the composite material was performed using a universal testing machine (UTM, AG-50kNX) of Shimadzu JP (Japan). According to ASTM-D638, the length is about 165 mm, the width is about 12.5 mm, and the thickness is about 3 mm. A specimen having a dog-bone shape was used. The load cell used was 50 kN, the crosshead speed was 5 mm/min, and the gauge length was 100 mm. Tensile strength and tensile modulus were obtained from the average values of 10 specimens per composite material.

In the case of the carbon fiber / ABS composite material of Fig. 4, the tensile strength in T-type, MT-type, I-type, and MI-type is about 51, 59, 62, 69 MPa (Fig. 4(a)), respectively, The tensile modulus of elasticity is about 8.1, 8.5, 9.6, and 9.9 GPa (Fig. 4(b)), respectively, and the tensile strength and tensile modulus are T-type, MT-type, I according to the degree of resin impregnation for carbon fibers in LFT pellets. -type, and the composite material manufactured with MI-type LFT was improved in order.

In the T-type carbon fiber/ABS composite material and the MT-type carbon fiber/ABS composite material, there was a region of carbon fiber that was not properly impregnated with resin, and the dispersibility of the carbon fiber was not good. As such, when the carbon fibers in the composite material are not evenly distributed in the resin matrix, the load applied from the outside is not evenly transmitted between the resin matrix and the carbon fibers constituting the composite material, thereby providing a cause of lowering the resistance to load. In addition, microdefects such as voids and defects may exist around carbon fibers that are not impregnated with resin. At this time, the discontinuity between the carbon fiber and the resin matrix causes failure, and consequently reduces the tensile strength and tensile modulus of the composite material.

On the other hand, in the composite material, carbon fibers are evenly dispersed and there is no area of carbon fiber impregnated with resin, or the area is relatively small between I-type carbon fiber/ABS composite material and MI-type carbon fiber/ABS composite material. In this case, when an external load is applied, the load is efficiently transferred between the adjacent carbon fiber and the resin matrix, and the tensile strength and tensile modulus of the composite material are improved as the load is relatively smaller than the initially applied load.

(2) Flexural test

5 shows (a) flexural strength and (b) flexural modulus of each type of carbon fiber/ABS composite manufactured by injection molding each type of LFT pellets. Flexural strength and flexural modulus were measured by the following method.

(Measurement of flexural strength and flexural modulus)

A three-point bending test of the composite material was performed using a universal testing machine (UTM, AG-50kNX) of Shimadzu JP (Japan). According to ASTM-D790, a specimen having a bar shape having a length of about 125 mm, a width of about 12.5 mm, and a thickness of about 3 mm was used. The load cell used was 50 kN, the crosshead speed was 5.1 mm/min, the span-to-depth ratio was 32:1, and the support span was 96 mm. Flexural strength and flexural modulus were obtained from the average values of 10 specimens per composite material.

In the case of the carbon fiber / ABS composite material of Figure 5, the flexural strength of T-type, MT-type, I-type and MI-type is about 98.7, 104.4, 107.7, 108.1 MPa (Fig. 6(a)), respectively, The flexural modulus is about 15.4, 17.0, 19.8, and 22.5 GPa (Fig. 6(b)), respectively, in the order of T-type, MT-type, I-type, and MI-type composite materials according to the degree of resin impregnation in LFT pellets. As a result, flexural strength and flexural modulus were improved.

In general, in fiber-reinforced composite materials, the interfacial properties between the reinforcing fibers and the polymer matrix play a very important role in the flexural strength and flexural modulus of the composite material. In the T-type and MT-type carbon fiber/ABS composite materials, there were carbon fiber bundles in which no interfacial bond was formed with the resin. The carbon fiber regions not impregnated with these resins act as voids and defects, and a stress concentration region is formed to lower the flexural strength and flexural modulus of the composite material. In addition, the carbon fibers are not well dispersed in the resin matrix, and the resin matrix existing between the carbon fibers is formed too thick or thin, so that the load cannot be evenly distributed, resulting in fracture of the composite material.

On the other hand, in the I-type and MI-type carbon fiber/ABS composite materials, the carbon fibers are evenly distributed between the resin matrix, so that the load applied from the outside is effectively transmitted to the neighboring carbon fibers and matrix, and the load is dispersed, resulting in the flexural strength of the composite material. and flexural modulus were improved.

Claims (5)

In the manufacturing method of the carbon fiber reinforced ABS composite material by the LFT process,
(a) extruding the molten ABS resin from the extruder into a resin impregnation die, and filling the inside of the resin impregnation die with the molten ABS resin;
(b) drawing carbon fibers from one end of a die for resin impregnation already filled with the molten ABS resin to the other end to prepare a towpreg impregnated with the molten ABS resin; and
(c) manufacturing a solid towpreg by cooling the towpreg impregnated with the molten ABS resin;
The method of claim 1,
Before cooling the towpreg impregnated with the molten ABS resin in step (c), the method for producing a carbon fiber reinforced ABS composite by the LFT process, characterized in that it further comprises the step of pressing.
The method of claim 1,
The resin impregnation die is a crosshead-die in which the molten ABS resin and the carbon fiber move together in the same horizontal direction and the carbon fiber is impregnated with the molten ABS resin, LFT A method of manufacturing a carbon fiber reinforced ABS composite material by the process.
A carbon fiber-reinforced ABS composite material prepared by any one of the methods selected from claims 1 to 3.
5. The method of claim 4,
The carbon fiber reinforced ABS composite material includes carbon fiber and ABS (Acrylonitrile-Butadiene-Styrene copolymer) resin, and has a tensile strength of 60 to 80 MPa, a tensile modulus of 9.0 to 15 GPa, and a flexural strength of 100 to 130 MPa, and , The carbon fiber reinforced ABS composite material, characterized in that the flexural modulus is 17.5 to 30 GPa.

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