KR20110035217A - Uni-directional sheet and hybrid composite using the same - Google Patents

Abstract

PURPOSE: A uni-directional sheet and a hybrid composite obtained using the same are provided to improve tensile strength and impact strength. CONSTITUTION: A uni-directional sheet contains 20-80 weight% of carbon fiber(1) and reinforcing fiber(2). The reinforcing fiber contains at least one fiber among aramid fiber and ultrahigh molecular polyethylene fiber. The carbon fibers and reinforcing fibers form bundles. The carbon fiber and reinforcing fiber contains impregnated resin(3).

Description

Uni-directional sheet and Hybrid composite using the same}

The present invention relates to a unidirectional sheet and a hybrid composite material prepared using the same, and more particularly, to a unidirectional sheet used in sports, aircraft, construction and civil engineering, and a hybrid composite material prepared using the same.

Currently, composite materials used in fields such as sports, aircraft, vehicles, construction, and civil engineering require high impact strength as well as high tensile strength and modulus.

Carbon fibers being used as reinforcing materials for such composites generally include PAN-based carbon fibers made from polyacrylonitrile and pitch-based carbon fibers made from pitch. Such carbon fibers are used in fields requiring form stability because they are lightweight and have high tensile strength and elastic modulus.

However, as carbon fibers are expensive and their impact strength is low, they have been limited to use in applications requiring high impact resistance and broadness.

The aramid fibers include para-aramid fibers having a structure in which benzene rings are linearly connected through an amide group, and meta-aramid fibers having a bent structure. Among them, para-aramid fibers have high strength, high elasticity, high heat resistance, and the like, and thus are used in body armor and protective clothing.

However, aramid fiber has better impact strength than carbon fiber but has low tensile strength and modulus of elasticity and thus cannot be used in fields such as aircraft, automobiles, and sports that require high strength.

Ultra high molecular weight polyethylene fibers have low specific gravity and high tensile strength, and are used in applications requiring light weight and high strength.

However, the ultra high molecular weight polyethylene fibers are not used in the fields of aircraft, automobiles, sports, etc., which require low heat resistance and low elastic modulus and high heat resistance and form stability.

Accordingly, the present invention relates to a unidirectional sheet and a hybrid composite prepared using the same, which can prevent problems caused by the above limitations and disadvantages of the related art.

An advantage of the present invention is to provide a unidirectional sheet and hybrid composite material capable of satisfying both tensile strength and impact strength by hybridizing reinforcing fibers including carbon fibers and aramid fibers or ultra high molecular weight polyethylene fibers in an optimal form.

In order to achieve the above advantages, and in accordance with the object of the present invention, carbon fibers; And reinforcing fibers comprising at least one of aramid fibers and ultra high molecular weight polyethylene fibers, wherein the carbon fibers and reinforcing fibers are arranged in one direction and alternately disposed.

In another aspect of the present invention, there is provided a hybrid composite material, which is molded by laminating and curing the one-way sheets.

It is to be understood that both the foregoing general description and the following detailed description are intended to illustrate or explain the invention, and to provide a more detailed description of the invention in the claims.

Unlike the conventional method of using only carbon fiber to manufacture a composite material, the present invention solves the conventional problem of lowering the impact strength of the composite material by alternately arranging reinforcing fibers such as carbon fibers and aramid fibers. There is.

Therefore, the hybrid composite material of the present invention can be used in a variety of fields such as aviation, automobiles, sports, civil engineering and construction, as well as having excellent tensile strength and elastic modulus, as well as good impact strength.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Accordingly, the invention includes all modifications and variations that fall within the scope of the invention as set forth in the claims and their equivalents.

As used herein, the term 'reinforcement fiber' refers to a reinforcement used to improve the impact strength of the composite material.

Hereinafter, with reference to the accompanying drawings will be described in detail specific embodiments of the one-way sheet 10 and the hybrid composite material according to the present invention.

1 is a view schematically showing a cross section of a one-way sheet 10 according to an embodiment of the present invention.

As shown in FIG. 1, the unidirectional sheet 10 of the present invention includes carbon fibers 1, aramid fibers and ultra high molecular weight polyethylene fibers (UHMWPE, Ultra High Molecular Weight Polyethylene) alternately arranged on the carbon fibers 1. Reinforcing fibers (2) comprising at least one of the fibers, and the resin (3) impregnated with the carbon fibers (1) and reinforcing fibers (2).

The carbon fiber 1 and the reinforcing fibers 2 constituting the unidirectional sheet 10 are arranged in an alternating form, which corresponds to the essential contents of the present invention. The carbon fiber 1 is excellent in tensile strength and elastic modulus but inferior in impact strength. However, the reinforcing fibers 2 are relatively inferior in tensile strength and modulus of elasticity but excellent in impact strength. By arranging the reinforcing fibers 2 excellent in such impact strength alternately between the carbon fibers 1, the tensile strength and modulus of elasticity of the one-way sheet 10 are not significantly reduced, and the impact strength can be improved.

The one-way sheet 10 may be changed in various materials and structures according to the use. That is, in the case of products requiring heat resistance, the carbon fiber 1 and the aramid fibers are alternately arranged to produce the unidirectional sheet 10, and in the case of products requiring high light weight and high strength, the carbon fiber 1 and the ultra high molecular weight polyethylene The fibers are arranged alternately to produce a unidirectional sheet 10.

In addition, as shown in (a) of Fig. 1, one strand of reinforcing fibers (2) is also called a tow (tow), which is usually composed of 1,000 to 100,000 filaments, often 'K' in thousand units. That is, the one-way sheet 10 can be manufactured by alternately arranging one strand of 1,000 filaments called 1K tow.

As another example, as illustrated in FIG. 1B, the unidirectional sheet 10 may be manufactured by alternately arranging the bundle of carbon fibers 1 and the bundle of reinforcing fibers 2. The number of fiber strands contained in the fiber bundle can be appropriately adjusted according to the use, because when the number of fiber strands is too large, the external impact cannot be properly distributed. Such a structure can be effective for large structures.

As another example, as shown in FIG. 1C, the unidirectional sheet 10 may be manufactured by varying the number of bundles of the carbon fiber 1 and the reinforcing fiber 2. That is, in the case of a product requiring high tensile strength and elastic modulus, the content of the carbon fiber 1 may be increased, and in the case of a product requiring impact strength, the content of the reinforcing fiber 2 may be increased.

Accordingly, the content of the carbon fiber (1) of the present invention may be preferably 20 to 80% by weight relative to the total fiber. If the content of the carbon fiber (1) is less than 20% by weight, composite materials having high strength and high modulus cannot be obtained. If the content of the carbon fiber (1) is more than 80% by weight, the composite material has excellent impact strength. Can't get it.

The present invention includes a unidirectional sheet 10 having a multilayer structure as shown in FIG. As described above, each of the layers of the multilayer structure is alternately arranged with the carbon fibers 1 and the reinforcing fibers 2 comprising at least one of aramid fibers and ultra high molecular weight polyethylene fibers. The fibers located on the upper and lower sides with respect to each contact surface are arranged so that the different kinds of fibers are shifted based on the upper and lower layers so that the different types of fibers contact each other. That is, when the carbon fiber 1 is located in the lower layer, the reinforcing fiber 2 is located in the upper layer in contact with the carbon fiber 1. On the contrary, when the reinforcing fiber 2 is located in the lower layer, the carbon fiber 1 is located in the upper layer in contact with the reinforcing fiber 2.

Therefore, the dissimilar fibers are arranged zigzag on the top and bottom, so that the impact from the outside can be quickly dispersed throughout the composite material, thereby further improving the impact strength of the composite material.

On the other hand, although the areas where the different types of fibers are not in contact with each other based on the contact surface of the multi-layer may include a portion less than 30% is preferred. If the area where the heterogeneous fibers do not contact is 30% or more, the tensile strength and the impact strength may not be greatly improved since the impact from the outside may not be smoothly dispersed.

As shown in FIG. 3, the unidirectional sheet 10 of the present invention has a form in which the carbon fibers 1 and the reinforcing fibers 2 are arranged in a uni-directional manner. If the fibers of the one-way sheet 10 are arranged in the form of a fabric, since bending is formed at the intersection of the weft and the warp yarn, the tensile strength and the elastic modulus are lowered and the impact strength is not significantly improved.

The unidirectional sheet 10 of the present invention may include a resin 3 impregnated in the carbon fiber 1 and the reinforcing fiber 2. The resin (3) serves to protect the reinforcement such as carbon fiber (1) from external friction, to maintain the shape, to uniformly distribute the external force and to improve the formability. The resin (3) may be used as a thermosetting resin such as epoxy, phenol, unsaturated polyester resin, and thermoplastic resin such as polyether ether ketone (PEEK), polyether sulfone (PES), polyphenylene sulfide (PPS) resin and the like. It is not necessarily limited thereto.

One-way sheet 10 according to the present invention can be used for various purposes. That is, the one-way sheet 10 described above may be laminated in various layers according to a use, and then cured to manufacture a composite material having various molded articles. Such a molded article can be used in various fields such as helmets, knee protectors, sports goods such as shoes, vehicles such as automobiles and aircrafts, construction and civil engineering of building reinforcement materials, and the like.

Next, the manufacturing method of the one-way sheet 10 of this invention is demonstrated. 4 is a view schematically showing a manufacturing process of the one-way sheet 10 according to an embodiment of the present invention.

According to one embodiment of the present invention, a method of manufacturing a unidirectional sheet 10 includes a carbon fiber 1 as a reinforcing material and a reinforcing fiber 2 including at least one fiber of aramid fiber and ultra high molecular weight polyethylene fiber in one direction. It comprises a process of making a sheet by arranging, adhering the resin 3 to the sheet, impregnating the resin 3 in the sheet, and winding the sheet impregnated with the resin 3.

In the process of making the sheet, first, as shown in FIG. 4, the carbon fibers 1 and the reinforcing fibers 2 are placed on the stand 21 and 22 at appropriate positions in the krill portion 20 according to the use. To place. Thereafter, the carbon fibers 1 and the reinforcing fibers 2 inserted into the stands 21 and 22 of the krill portion 20 are unwound and inserted into a comb 23 having a plurality of grooves divided into predetermined widths. Arrange to make a single layer sheet.

The process of attaching the resin 3 to the sheet consists of attaching the resin coating film 4 to both surfaces of the sheet in which the carbon fibers and the reinforcing fibers 2 are arranged in one direction. The resin coating film 4 is composed of a resin film 3a and a release paper 5 that is easily attached and detached and a resin film 3a attached to one surface of the release paper 5. At this time, the resin coating film 4 is supplied such that the direction in which the resin 3 is attached is directed toward the sheet surface so that the surface of the sheet and the resin film 3a can contact each other. The resin coating film 4 is supplied to both surfaces of the sheet by the resin coating film supply rollers 30 respectively installed on the upper and lower portions of the sheet.

The process of impregnating the resin (3) in the sheet is made through the process of passing the sheet with the resin coating film (4) through the hot roller (40). The hot roller 40 is maintained at a predetermined temperature and pressure. Therefore, when the sheet to which the resin coating film 4 is attached passes through the hot roller 40 which maintains a predetermined temperature and pressure, the resin of the resin coating film can be easily moved by the high temperature, Thereby impregnating the resin into the carbon fibers and the reinforcing fibers 2.

The process of winding the sheet impregnated with the resin 3 may include recovering the release paper 5 from one surface of the sheet, attaching the release film 6 to both surfaces of the one-way sheet 10, and the release film ( It consists of a process of winding the one-way sheet 10 attached 6) to the winding roller 50.

In the process of recovering the release paper 5 from one surface of the sheet, the release paper 5 attached to both surfaces of the sheet passing through the hot roller 40 is wound by using a release paper collection roller 31 provided on the upper and lower portions thereof. Is performed. The release paper 5 thus recovered can be reused to produce the resin coated film 4.

In the process of attaching the release film 6 to both surfaces of the one-way sheet 10, the release film is supplied by a release film supply roller 60 installed at upper and lower sides, and the release film 6 is the one-way sheet. It is attached to both surfaces of (10). Therefore, since the release film 6 is attached to both surfaces of the one-way sheet 10 wound on the winding roller 50, the one-way sheets 10 do not stick together even if they are left for a long time.

Next, the method of manufacturing the multilayer one-way sheet 10 is demonstrated. As an example, a method of manufacturing the two-layered one-way sheet 10 will be described.

In order to manufacture the two-layered one-way sheet 10 as shown in Fig. 2, it is possible to modify the process of making the sheet by arranging the carbon fibers 1 and the reinforcing fibers 2, which are the reinforcing materials described above, in one direction. That is, the carbon fibers 1 and the reinforcing fibers 2 are installed so that the combs 23 are respectively provided on the upper and lower portions, and the corresponding fibers in the vertical direction of each of the upper combs 23 and the lower combs 23 are different fibers. ).

On the other hand, the resin film 3a used is twice as thick as the resin film 3a used to produce the single direction sheet 10 of a single layer. That is, as the thickness of the multilayer increases, it is preferable to also increase the thickness of the resin film 3a. In addition, as the thickness of the multilayer increases, it is preferable that the temperature and pressure of the hot roller 40 be set somewhat higher correspondingly.

In addition, the manufacturing method of the one-way sheet 10 is not limited to what was mentioned above. That is, as long as it enables the process which arrange | positions the carbon fiber 1 and the reinforcement fiber 2 in one direction, and impregnates the resin 3, any may be sufficient. For example, the process of making the sheet by arranging the carbon fibers and the reinforcing fibers 2 in one direction may be performed by using a drum in which the carbon fibers and the reinforcing fibers 2 are wound in a predetermined form without using the above-described krill portion 20. You can also use In addition, the process of impregnating the resin (3) in the sheet, instead of the process of using the resin coating film (4), carbon sheets and reinforcing fibers (2) are mixed and immersed in a resin solution, the sheet is immersed in a resin solution to dry the resin ( It may also be carried out using a wet process that impregnates 3).

Next, the method of manufacturing a composite material using the above-mentioned one-way sheet 10 is demonstrated.

Various composite materials may be manufactured by forming the above-described one-way sheets 10 by stacking and curing the layers in various layers. That is, the one-way sheet 10 is cut to a predetermined size, laminated at a predetermined orientation angle, and then molded into various shapes by heating and compressing the laminate using an autoclave or a hot press roll to manufacture a composite material. Can be.

Hereinafter, the present invention will be described in detail through Examples and Comparative Examples. However, the following examples are only intended to help the understanding of the present invention, and the scope of the present invention should not be limited.

Sample Preparation

(1) carbon fiber

'Toreca T700SC-3K-50C' (trade name) having a tensile strength of 4900 MPa, a tensile modulus of 235 GPa, and a fiber specific weight of 1.80 g / cm ³ was used.

(2) aramid fiber

Tensile strength 2900 MPa, Tensile modulus 95 GPa, and fiber specific gravity 1.44 g / cm ³ 'Heracron HF200' (trade name, manufactured by Kolon Corporation) was used.

(3) ultra high molecular weight polyethylene fiber

A tensile strength of 2700 MPa, a tensile modulus of 89 GPa, a fiber specific weight of 0.97 g / cm ³ , and 'Dyneema SK60' (Dyneema, manufactured by Toyobo Co., Ltd.) having a fineness of 1,500 deniers were used.

Example  One

One-way sheet 10 was manufactured using the same process as in FIG. 4. First, aramid fiber is used as the carbon fiber 1 and the reinforcing fiber 2, and the carbon fiber 1 and the aramid fiber are alternately inserted into the stands 21 and 22 of the krill part 20, and the krill part ( In the stand 21 and 22 of 20), the carbon fiber 1 and the aramid fiber are respectively unwound and inserted into the comb 23 so that one strand of carbon fiber 1 and one strand of aramid fiber are alternately arranged in one direction. Made. Thereafter, the resin coating film 4 is supplied to the upper and lower surfaces of the sheet through the resin coating film supply rollers 30 installed on the upper and lower portions of the sheet, respectively, thereby providing the resin coating film 4 with the amount of the sheet. After adhering to the surface, the hot roller 40 was passed through to impregnate the resin 3 in the sheet. At this time, the hot roller 40 was maintained at a temperature of 120 ° C and a line pressure of 8 kg / cm. Thereafter, the release paper 5 attached on the sheet and the lower part is wound and collected on the release paper collecting roller 31, and the release film 6 is one-way sheet by the release film supply roller 60 installed on the sheet and the lower part. It is supplied to both surfaces of (10). Thereafter, the one-way sheet 10 having the release film 6 attached to both surfaces thereof was obtained by winding the winding roller 50. At this time, the one-way sheet 10 from which the release film 6 was removed from both surfaces contained 35% by weight of the resin 3. A composite composite material having a thickness of 1 mm by stacking the unidirectional sheet 10 manufactured in this way in multiple layers in the same direction and pressing for 2 hours using an autoclave maintained at a temperature of 130 ° C. and a pressure of 0.3 MPa. Was prepared.

Comparative example  One

In Example 1 described above, a hybrid composite material was prepared in the same manner as in Example 1 except that the composite material was manufactured using only the carbon fiber 1 instead of the carbon fiber 1 and the aramid fiber.

Example  2

In Example 1 described above, a hybrid composite material was prepared in the same manner as in Example 1, except that ultrahigh molecular weight polyethylene (UHMWPE) fibers were used instead of the aramid fibers, which are the reinforcing fibers (2).

Example  3

In Example 1 described above, except that the carbon fibers (1) and aramid fibers are properly disposed so that three strands of aramid fibers are alternately arranged in three directions of the carbon fibers (1) so as to be arranged in one direction. Hybrid composite materials were prepared.

Example  4

In Example 1 described above, the same method as in Example 1 except that the carbon fibers (1) and the aramid fibers are properly disposed so that two strands of aramid fibers are alternately arranged in three directions of the carbon fibers (1). Hybrid composite material was prepared.

Example  5

In Example 1 described above, except that the carbon fibers 1 and the aramid fibers are appropriately arranged so that one strand of aramid fibers is alternately arranged on three strands of the carbon fibers 1 so as to be arranged in one direction. Hybrid composite materials were prepared.

Example  6

In Example 1 described above, as shown in FIG. 2, in order to manufacture the multilayer unidirectional sheet 10 in which the single layers in which the carbon fibers 1 and the aramid fibers are arranged in one direction are formed in the upper and lower layers, respectively, the krill portion 20 In addition to the carbon fiber (1) and aramid fiber installed in the upper and lower two combs (23) to prepare a two-layer sheet, except using a resin coating film (4) of twice the thickness Prepared a hybrid composite material in the same manner as in Example 1.

Tensile strength, elastic modulus and impact strength of each of the composite composite materials prepared by Examples 1 to 6 and Comparative Example 1 were measured by the following method, and the results are shown in Table 1 below.

Measurement of Tensile Strength and Modulus of Hybrid Composites

Tensile strength and modulus of elastic composite materials were measured by the method of ASTM D3039 (1995). At this time, the test piece was 6.4 mm in width and 14 mm in length.

Impact Strength Measurement of Hybrid Composites

The impact strength of the hybrid composite material was measured by the method of ASTM D256. At this time, the test piece was 12.7 mm in width and 64 mm in length.

division Ingredient Composition ratio (strand: strand) shape Tensile Strength (MPa) Modulus of elasticity Impact Strength (kJcm ^-3 ) Example 1 Carbon + Aramid 1: 1 fault 1220 114 102 Example 2 Carbon + UHMWPE 1: 1 fault 1180 106 84 Example 3 Carbon + Aramid 3: 3 fault 1230 116 94 Example 4 Carbon + Aramid 3: 2 fault 1280 120 81 Example 5 Carbon + Aramid 3: 1 fault 1340 126 66 Example 6 Carbon + Aramid 1: 1 Second floor 1220 113 113 Comparative Example 1 carbon - fault 1450 135 20

1 is a view schematically showing a cross section of a one-way sheet according to an embodiment of the present invention.

2 is a view schematically showing a cross section of a one-way sheet according to another embodiment of the present invention.

3 is a perspective view schematically illustrating the one-way sheet of FIG. 1.

4 is a view schematically showing a manufacturing process of a one-way sheet according to an embodiment of the present invention.

<Description of Main Parts of Drawings>

1: carbon fiber 2: reinforcing fiber

3: resin 4: resin coated film

5: release paper 6: release film

10: one-way sheet

20: krill portion 30: resin coating film feed roller

40: hot roller 50: winding roller

60: release film feed roller

Claims (7)

Carbon fiber; And Including reinforcing fibers comprising at least one of aramid fibers and ultra high molecular weight polyethylene fibers, Wherein said carbon fibers and reinforcing fibers are arranged in one direction and alternately arranged. The method of claim 1, The unidirectional sheet further comprises a resin impregnated with the carbon fiber and the reinforcing fiber. The method of claim 1, The carbon fibers and the reinforcing fibers are arranged in one direction and alternately arranged layers form a multilayer, And a region in which the fibers located on the upper and lower sides of the multilayer contact surfaces are arranged such that the fibers of the different types are shifted based on the upper and lower layers such that the fibers are in contact with each other. The method of claim 3, And a region in which heterogeneous fibers are in contact with a region not in contact with each of the multilayer contact surfaces, wherein an area in which the heterogeneous fibers are in contact is 30% or more. The method of claim 1, The content of the carbon fiber is a one-way sheet, characterized in that 20 to 80% by weight relative to the total fiber. The method of claim 1, The carbon fiber or the reinforcing fiber is a one-way sheet, characterized in that the bundle. Hybrid composite material, characterized in that formed by curing after laminating the unidirectional sheets according to any one of claims 1 to 6.

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