KR102483485B1 - Long fiber reinforced thermoplastics and molded article fabricated by the same - Google Patents

Abstract

The present invention is a long fiber-reinforced thermoplastic, wherein a cross section of the long-fiber-reinforced thermoplastic includes at least two carbon fiber regions and at least two glass fiber regions in a thermoplastic resin matrix, and the at least two carbon fiber regions and The at least two glass fiber regions are arranged alternately with each other, and relates to a long fiber-reinforced thermoplastic and a molded article manufactured using the same.

Description

Long fiber-reinforced thermoplastics and molded products manufactured using them

The present invention relates to a long fiber-reinforced thermoplastic and a molded article manufactured using the same. Specifically, the present invention relates to a long-fiber-reinforced thermoplastic that simultaneously includes carbon fibers and glass fibers, and a molded product manufactured using the same.

Fiber-reinforced composites are composite materials composed of a resin matrix and fibers that function to mechanically improve the strength and elasticity of the resin matrix material. Such fiber-reinforced composites may have mechanical strength comparable to that of metal materials, and exhibit lighter properties than metal materials.

Long fiber reinforced thermoplastics (LFT), which is a type of fiber-reinforced composite material, is manufactured using a fiber-reinforced material and a thermoplastic resin. The difference between LFT and conventional short fiber reinforced composites lies in the length of the fibers. The fiber length in LFT is equal to the length of unit composites such as pellets. That is, the fibers in the LFT are provided continuously in the longitudinal direction without being cut. In LFT manufacture, continuous strands of fiber rovings are drawn through a die, coated and impregnated with a thermoplastic resin. This continuous rod of reinforced plastic is then cut and pelletized.

As the fiber reinforcement of the LFT, glass fibers and carbon fibers may be used. In the case of glass fiber-based LFT, it does not shrink or elongate according to changing environmental conditions, so it has excellent dimensional stability, and further has high tensile strength, heat resistance, corrosion resistance and impact resistance. However, glass fibers have limitations in further improving mechanical properties such as tensile strength and stiffness, and also have limitations in further reducing weight. In the case of carbon fiber-based LFT, it has excellent strength and stiffness and excellent electrical properties, but the carbon fiber processing process is very difficult and very expensive (about 12 times more expensive than glass fiber-based LFT). There is a problem with

Korean Registration Publication No. 10-1790577 discloses manufacturing a resin molded article by mixing fiber-reinforced plastic pellets, that is, glass-fiber-based fiber-reinforced plastics and carbon-fiber-based fiber-reinforced plastics each containing fiber reinforcements of different materials, there is. However, as proposed in Korean Registration Publication No. 10-1790577, when a resin molded product is manufactured using pellets of different materials, the quality uniformity problem of the molded product due to the decrease in kneading due to the difference in specific gravity between the pellets of different materials, or Overall physical property degradation due to non-uniform mixing may also be a problem. Therefore, there is a need for research into a method that can more easily combine the advantages of glass fiber-based fiber-reinforced plastics and carbon fiber-based fiber-reinforced plastics.

The present invention is to provide a long fiber-reinforced thermoplastic and a molded article manufactured using the same. Specifically, the present invention is to provide a molded article with excellent physical properties by providing a long fiber-reinforced thermoplastic that can easily solve the problem of non-uniformity in the case of manufacturing a molded article using pellets of different materials.

In one embodiment of the present invention, in the long fiber-reinforced thermoplastic, a cross section of the long-fiber-reinforced thermoplastic includes at least two carbon fiber regions and at least two glass fiber regions in a thermoplastic resin matrix, and the at least two The two carbon fiber regions and the at least two glass fiber regions are alternately arranged, and the long fiber-reinforced thermoplastic is provided.

Another embodiment of the present invention provides a molded article manufactured using the long fiber-reinforced thermoplastic.

The long fiber-reinforced plastic according to the present invention has the advantage of easily solving the non-uniformity problem in the case of manufacturing a molded product by mixing each of the carbon fiber-based long-fiber-reinforced plastic and the glass-fiber-based long-fiber reinforced plastic. That is, in the case of manufacturing a molded product using the long fiber-reinforced plastic according to the present invention, the kneading property between the carbon fibers and the glass fibers can be maximized even if the kneading process for homogeneous mixing is omitted. Through this, the molded article manufactured using the long-fiber-reinforced plastic according to the present invention can secure homogeneous physical properties as well as high appearance characteristics and impact strength.

1 and 2 are diagrams of a cross-sectional shape of a long fiber-reinforced plastic according to an exemplary embodiment of the present invention.
3 is an OM (optical microscope) image of the surface of an injection-molded article manufactured using long-fiber-reinforced plastic pellets according to Comparative Example 1.
4 is an OM (optical microscope) image of the surface of an injection-molded article manufactured using long-fiber-reinforced plastic pellets according to Comparative Example 2.
5 is an OM (optical microscope) image of the surface of an injection-molded article manufactured using the long-fiber-reinforced plastic pellets according to Example 1.

In this specification, when a part is said to "include" a certain component, it means that it may further include other components without excluding other components unless otherwise stated.

In the present specification, the unit "wt%" may mean the ratio of the weight of each component to the total component. Further, the wt% of carbon fiber and glass fiber in the long fiber-reinforced thermoplastic can be determined by using an ash measurement method in which the weight of the remaining fiber is measured after heat treatment of the resin in a nitrogen atmosphere.

The inventors of the present invention, as a result of research on manufacturing a molded product using carbon fiber-based long fiber-reinforced plastic pellets and glass-fiber-based long-fiber reinforced plastic pellets together, the kneading property due to the difference in specific gravity between the pellets of different materials is poor, resulting in a molded product It has been recognized that the quality is not uniform and, accordingly, the degradation of physical properties also occurs. In this regard, as a result of continuing research on uniformly mixing the carbon fiber-based long fiber-reinforced plastic pellets and the glass-fiber-based long fiber-reinforced plastic pellets, the present invention has been completed. Specifically, the inventors of the present invention contain carbon fibers and glass fibers together in a single long-fiber reinforced plastic, but when they are arranged in a specific position, the kneading property of carbon fibers and glass fibers in a molded article to be manufactured is maximized, and the existing dissimilar materials It has been found that there is no need to perform a separate process for homogeneous mixing of the pellets.

Hereinafter, the present invention will be described in detail.

In one embodiment of the present invention, in the long fiber-reinforced thermoplastic, a cross section of the long-fiber-reinforced thermoplastic includes at least two carbon fiber regions and at least two glass fiber regions in a thermoplastic resin matrix, and the at least two The two carbon fiber regions and the at least two glass fiber regions are alternately arranged, and the long fiber-reinforced thermoplastic is provided.

The long fiber-reinforced thermoplastic according to the present invention includes carbon fiber (CF) and glass fiber (GF) at the same time, and they are composed of a single strand impregnated with a thermoplastic resin. Furthermore, the carbon fibers and glass fibers in the long-fiber-reinforced thermoplastic according to the present invention are continuous fibers, respectively, and are arranged in the longitudinal direction of the long-fiber-reinforced thermoplastic, and may have the same length as the long-fiber-reinforced thermoplastic. For example, when the long fiber-reinforced thermoplastic is manufactured in the form of a pellet, the carbon fiber and the glass fiber may have the same length as the length of the pellet.

In the cross section of the long fiber-reinforced thermoplastic according to the present invention, at least two carbon fiber regions and the at least two glass fiber regions may be alternately arranged.

1 and 2 are diagrams of a cross-sectional shape of a long fiber-reinforced plastic according to an exemplary embodiment of the present invention. Specifically, according to FIGS. 1 and 2, in the cross section of the long fiber-reinforced thermoplastic according to the present invention, two or more carbon fiber regions 20 and two or more glass fiber regions 30 provided in the thermoplastic resin matrix 10 ) is provided, indicating that the arrangement direction of the carbon fiber regions 20 and the arrangement direction of the glass fiber regions 30 cross each other.

A carbon fiber region in the present specification may mean a region in which a plurality of carbon fibers are densely arranged in bundles. Similarly, the glass fiber region in the present specification may mean a region in which a plurality of glass fibers are densely arranged in bundles. Specifically, referring to FIGS. 1 and 2 , each carbon fiber region 20 is a region in which carbon fibers are densely provided, and each glass fiber region 30 means a region in which glass fibers are densely provided. can do.

According to one embodiment of the present invention, in each carbon fiber region, the carbon fiber may have a fiber density of 6 K or more and 24 K or less. Specifically, within each carbon fiber region, the carbon fibers may have a fiber density of 12 K or more and 24 K or less. Here, the fiber density unit K may mean “the number of filaments (×10 ³ )/fiber bundle”.

According to one embodiment of the present invention, in each glass fiber area, the glass fiber may have a fiber density of 300 TEX or more and 2,400 TEX or less. Specifically, in each glass fiber region, the glass fibers may have a fiber density of 1,200 TEX or more and 2,400 TEX or less. Here, the fiber density unit TEX may mean "number of grams/1 km of fiber".

When the fiber density of the carbon fibers in the carbon fiber region and the fiber density of the glass fibers in the glass fiber region are within the above ranges, too many strands of fibers are included in the long fiber-reinforced thermoplastic to be manufactured, so that the thermoplastic resin is not sufficiently impregnated. can be prevented, and the curing time of the impregnated thermoplastic resin can be controlled so that it is not too long. Furthermore, by including an appropriate number of fiber strands in the manufactured long-fiber-reinforced thermoplastic, the thickness of the long-fiber-reinforced thermoplastic is prevented from being enlarged, and convenience of use can be improved when pelletized and used.

According to an exemplary embodiment of the present invention, the total content of carbon fibers and glass fibers in the long fiber-reinforced thermoplastic may be 20 wt% or more and 60 wt% or less. If the total content of the fibers exceeds 60 wt%, the volume of the thermoplastic resin matrix in the long fiber-reinforced thermoplastic cannot be sufficiently secured, and thus manufacturing is impossible or problems such as breakage after manufacturing may occur. In addition, when the total content of the fibers is less than 20 wt%, the content of the reinforcing material in the long fiber-reinforced thermoplastic is not sufficiently secured, making it difficult to secure sufficient physical properties.

According to an exemplary embodiment of the present invention, the weight ratio of carbon fibers and glass fibers in the long fiber-reinforced thermoplastic may be 1:1 to 1:3.

According to one embodiment of the present invention, the long fiber-reinforced thermoplastic may be pelletized. Specifically, the long fiber-reinforced thermoplastic may be pelletized by being cut to a length of 9 mm or more and 13 mm or less.

The thermoplastic resin matrix may be a cured material of a thermoplastic resin into which the carbon fibers and the glass fibers are impregnated. Specifically, the thermoplastic resin matrix is selected from polyester resins, vinyl ester resins, phenolic resins, epoxy resins, polyamide resins, polyimide resins, polypropylene resins, polyethylene resins, polycarbonate resins, polyvinyl chloride resins and styrene resins. It may be derived from a thermoplastic resin containing one or more species that are. However, it is not limited thereto, and resins for impregnation commonly used in the art may be applied without limitation.

As the glass fiber, glass fibers commonly used in the art may be used without limitation. For example, the glass fibers include A-type glass fibers, C-type glass fibers, G-type glass fibers, E-type glass fibers, S-type glass fibers, E-CR-type glass fibers, R-type glass fibers, wool glass fibers, and biomaterials. At least one type of glass fiber selected from soluble glass fibers may be included.

As the carbon fiber, carbon fibers commonly used in the art may be used without limitation. For example, the carbon fibers may be PAN-based carbon fibers, pitch-based carbon fibers, rayon-based carbon fibers, or lignin-based fibers, depending on the precursor used, and have a turbostatic structure ( turbostratic structure) and/or graphitic structure.

The glass fibers and/or the carbon fibers may be coated with a sizing composition during or after the fiber forming process. As the sizing composition, sizing compositions commonly used in the art may be used without limitation, and sizing may also be performed by a method known in the art.

In the long fiber-reinforced plastic according to an exemplary embodiment of the present invention, carbon fiber bundles (ie, carbon fiber regions) and glass fiber bundles (ie, glass fiber regions) provided therein are provided alternately with each other, so that When an injection or extrusion molded product is manufactured by using the carbon fiber and glass fiber, it is possible to significantly improve the physical properties of the molded product by maintaining a high kneading property of the carbon fiber and the glass fiber without a separate mixing process.

Another embodiment of the present invention provides a molded article manufactured using the long fiber-reinforced thermoplastic.

According to an exemplary embodiment of the present invention, the molded article may be an injection molded article or an extrusion molded article manufactured using the long fiber-reinforced thermoplastic.

According to an exemplary embodiment of the present invention, the molded article may be manufactured through injection molding or extrusion molding using the pelletized long fiber-reinforced thermoplastic.

According to one embodiment of the present invention, the bending strength of the molded article may be at least 170 MPa, and the impact strength may be at least 180 J/m.

Hereinafter, examples will be described in detail to explain the present invention in detail. However, embodiments according to the present invention can be modified in many different forms, and the scope of the present invention is not construed as being limited to the embodiments described below. The embodiments herein are provided to more completely explain the present invention to those skilled in the art.

[ Example One]

After preparing two glass fiber bundles having a fiber density of 1200 TEX and two carbon fiber bundles having a fiber density of 12 K, each of them is passed through an individual die and released, and the two carbon fiber regions and the at least two glass fibers are separated. Plied and drawn in a single batch so that the regions are alternated with each other. Further, the fibers to be pulled out were passed through an impregnation unit into which the thermoplastic resin was injected, and then cured to prepare a single-stranded long-fiber-reinforced thermoplastic containing heterogeneous fibers. Furthermore, the long fiber-reinforced thermoplastics thus prepared were cut and pelletized. Furthermore, the manufactured pellets were supplied to an injection molding machine to manufacture an injection molded product.

[ comparative example One]

After preparing one glass fiber bundle having a fiber density of 2400 TEX and one carbon fiber bundle having a fiber density of 24 K, releasing them respectively and drawing them out so that the glass fiber bundle and the carbon fiber bundle are arranged side by side. , Long fiber-reinforced thermoplastics and injection molded products were prepared in the same manner as in Example 1.

[ comparative example 2]

After preparing two glass fiber bundles with a fiber density of 1200 TEX and two carbon fiber bundles with a fiber density of 12 K, release them respectively and arrange the two carbon fiber bundles and the two glass fiber bundles side by side with each other. A long-fiber-reinforced thermoplastic and an injection-molded article were prepared in the same manner as in Example 1, except that they were drawn out.

[ comparative example 3]

Using only one glass fiber bundle having a fiber density of 2400 TEX, a long fiber-reinforced thermoplastic and an injection-molded product were manufactured in the same manner as in Example 1.

[ comparative example 4]

A long fiber-reinforced thermoplastic and an injection-molded product were manufactured in the same manner as in Example 1, using only one carbon fiber bundle having a fiber density of 12 K.

[ comparative example 5]

The injection-molded product of Example 1 was obtained by dry mixing the glass fiber-based long-fiber-reinforced thermoplastic pellets according to Comparative Example 3 and the carbon-fiber-based long-fiber-reinforced thermoplastic pellets according to Comparative Example 4 at a weight ratio of 5:3. was manufactured.

The long fiber-reinforced thermoplastic pellets prepared according to Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 5 are shown in Table 1 below.

Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 5

heterogeneous fibers
arranged alternately heterogeneous fibers
arranged in parallel heterogeneous fibers
arranged in parallel Heterogeneous Pellets
dry mixed

Furthermore, a schematic view of the glass fiber region and the carbon fiber region in the cross section of the long fiber reinforced thermoplastic (LFT) pellets prepared according to Example 1 and Comparative Examples 1 to 5, the density of the long fiber reinforced thermoplastic and the use thereof Table 2 shows the physical properties of the injection-molded product manufactured by the above.

<How to measure physical properties>

- Flexural strength: The flexural strength of the injection-molded article manufactured using INSTRON4466 (INSTRON Co.) was measured in a room temperature atmosphere in accordance with ASTM D790.

-Impact strength: In a method according to ASTM D256, the impact strength of the injection-molded article made of the notched specimen was measured using Impact Tester IT (TOYOSEIKI Co., Ltd.) in a room temperature atmosphere.

<evaluation>

According to the results of Table 2, the injection-molded article according to Example 1 using long-fiber-reinforced plastic pellets in which heterogeneous fibers are alternately arranged is Comparative Example 1 and Comparative Example 2 using long-fiber-reinforced plastic pellets in which heterogeneous fibers are arranged in parallel In comparison, both the flexural strength and impact strength were excellent.

In addition, it was confirmed that the injection-molded product according to Comparative Example 3 using long-fiber-reinforced plastic pellets containing only glass fibers had significantly low flexural strength, and the injection-molded product according to Comparative Example 4 using long-fiber-reinforced plastic pellets containing only carbon fibers Although the flexural strength was excellent, it was confirmed that the impact strength was lower than that of Example 1.

Furthermore, it was confirmed that the injection-molded product according to Comparative Example 5, in which long-fiber-reinforced plastic pellets containing only glass fibers and long-fiber-reinforced plastic pellets containing only carbon fibers were dry-mixed, exhibited lower flexural strength and impact strength than those of Example 1. .

3 is an OM (optical microscope) image of the surface of an injection-molded article manufactured using long-fiber-reinforced plastic pellets according to Comparative Example 1. According to FIG. 3, fiber agglomeration was easily observed on the surface of the injection-molded product according to Comparative Example 1, and the surface level difference was very large.

4 is an OM (optical microscope) image of the surface of an injection-molded article manufactured using long-fiber-reinforced plastic pellets according to Comparative Example 2. According to FIG. 4, as in Comparative Example 1, carbon fiber bundles and glass fiber bundles are arranged side by side, but in Comparative Example 2, in which two carbon fiber bundles and two glass fiber bundles are applied, respectively, compared to Comparative Example 1, the aggregation of the fibers is slightly It was confirmed that the improvement was confirmed, and the surface step was also slightly reduced.

5 is an OM (optical microscope) image of the surface of an injection-molded article manufactured using the long-fiber-reinforced plastic pellets according to Example 1. According to FIG. 5, it was confirmed that the injection-molded product manufactured according to Example 1 had significantly reduced fiber aggregation compared to Comparative Examples 1 and 2, and almost no surface step was found.

According to the results of Table 2 and FIGS. 3 to 5, when using the long fiber-reinforced plastic pellets according to Example 1, an injection-molded article having a very good fiber kneading degree was manufactured without a separate mixing process in Comparative Example 5. Able to know. In addition, as can be seen from the results according to Example 1, Comparative Example 1 and Comparative Example 2, the physical properties of the manufactured injection-molded article can vary greatly depending on the arrangement of carbon fibers and glass fibers in the single-stranded long-fiber-reinforced plastic. Able to know. That is, when the glass fiber bundle and the carbon fiber bundle are alternately arranged as in Example 1, it was confirmed that very excellent physical properties can be implemented.

10: thermoplastic resin matrix
20: carbon fiber area
30: glass fiber area

Claims (5)

In the long fiber reinforced thermoplastic,
The cross section of the long fiber-reinforced thermoplastic includes at least two carbon fiber regions and at least two glass fiber regions in a thermoplastic resin matrix, and the at least two carbon fiber regions and the at least two glass fiber regions are alternately Arranged, a long fiber reinforced thermoplastic. The method of claim 1,
Within each carbon fiber region, the carbon fibers have a fiber density of 6 K or more and 24 K or less,
A long fiber-reinforced thermoplastic, characterized in that, in each glass fiber region, the glass fibers have a fiber density of 300 TEX or more and 2,400 TEX or less. The method of claim 1,
In the long fiber-reinforced thermoplastic, the total content of carbon fibers and glass fibers is 20 wt% or more and 60 wt% or less, characterized in that, long fiber-reinforced thermoplastics. The method of claim 1,
In the long fiber-reinforced thermoplastic, the weight ratio of carbon fibers and glass fibers is 1: 1 to 1: 3, characterized in that, the long fiber-reinforced thermoplastic. The method of claim 1,
The long fiber-reinforced thermoplastic is characterized in that the pelletized, long fiber-reinforced thermoplastic.

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