CROSS-REFERENCE TO RELATED APPLICATION

The present application is a national stage filing under 35 U.S.C § 371 of PCT application number PCT/KR2018/009463 filed on Aug. 17, 2018 which is based upon and claims the benefit of priorities to Korean Patent Application No. 10-2017-0147332, filed on Nov. 7, 2017, Korean Patent Application No. 10-2018-0005682, filed on Jan. 16, 2018, and Korean Patent Application No. 10-2018-0094883, filed on Aug. 14, 2018, in the Korean Intellectual Property Office, which are incorporated herein in their entireties by reference.

TECHNICAL FIELD

The present disclosure relates to a method for producing an unidirectionally-aligned discontinuous fiber-reinforced composite, an unidirectionally-aligned discontinuous fiber-reinforced composite, and a sandwich structure.

BACKGROUND

A continuous fiber-reinforced composite has excellent mechanical strength, but has low elongation, leading to a disadvantage that there is difficulty in molding of a part with a complex design using the continuous fiber-reinforced composite. On the other hand, a randomly aligned fiber-reinforced composite is excellent in formability but has a disadvantage in that mechanical strength thereof is relatively lowered.

A unidirectionally-aligned discontinuous fiber-reinforced composite (ADF) in which short fibers are discontinuously and unidirectionally aligned has both of high mechanical strength and excellent formability. Thus, the ADF is recently attracting attention as means to improve performance of recycled carbon fiber and glass fiber.

A conventional unidirectionally-aligned discontinuous fiber-reinforced composite (ADF) have been produced primarily using a top-down process such as stretch broken or slitting approach in which a continuous fiber reinforced material is cut in a post process.

DISCLOSURE

Technical Purpose

However, the approach of cutting the continuous fiber reinforced material in the post-process may not be applied to a recycled reinforcing fiber mainly having a short-fiber type, and has limitation in improving the formability.

A purpose of the present disclosure is to provide a method to produce an unidirectionally-aligned discontinuous fiber-reinforced composite (ADF) using reinforcing short-fibers.

Further, another purpose of the present disclosure is to provide an unidirectionally-aligned discontinuous fiber-reinforced composite (ADF) obtained using the method for producing the unidirectionally-aligned discontinuous fiber-reinforced composite (ADF).

Further, still another purpose of the present disclosure is to provide a sandwich structure including the unidirectionally-aligned discontinuous fiber-reinforced composite (ADF) obtained using the method for producing the unidirectionally-aligned discontinuous fiber-reinforced composite (ADF).

However, the technical purposes that the present disclosure seeks to achieve are not limited to those as mentioned above. Still other purposes as not mentioned will be clearly understood by those skilled in the art from following descriptions.

Technical Solution

A method for producing an unidirectionally-aligned discontinuous fiber-reinforced composite (ADF) includes discontinuously and unidirectionally aligning short-fibers on a polymer base using an air-laid method.

The method for producing the unidirectionally-aligned discontinuous fiber-reinforced composite includes applying air to the short-fibers such that the short-fibers are inserted into a plurality of channels; and aligning the short-fibers discharged from the plurality of channels unidirectionally on the polymer base disposed below the plurality of channels. Each of the plurality of channels has an outlet area smaller than an inlet area thereof, and includes a hollow having an inclined face extending from the inlet to the outlet.

An unidirectionally-aligned discontinuous fiber-reinforced composite (ADF) is obtained using the method for producing the unidirectionally-aligned discontinuous fiber-reinforced composite and includes a polymer base; and short-fibers discontinuously and unidirectionally aligned on the polymer base. A percentage of short-fibers whose long-sides are aligned at an angle within +14° with respect to an exact unidirectional alignment direction is 92% or greater.

The unidirectionally-aligned discontinuous fiber-reinforced composite (ADF) satisfies a following relationship (1):
0.92≤(0° specimen tensile strength−90° specimen tensile strength)/0° specimen tensile strength<1.00  Relationship (1),

wherein in the relationship 1,

the 0° specimen tensile strength refers to a tensile strength in a direction parallel to the unidirectionally aligned direction of the short-fibers,

wherein the 90° specimen tensile strength refers to a tensile strength in a direction perpendicular to the unidirectionally aligned direction of the short-fibers.

A sandwich structure includes a first skin layer; a second skin layer; and a core layer disposed between the first skin layer and the second skin layer, wherein at least one of the first skin layer or the second skin layer includes the unidirectionally-aligned discontinuous fiber-reinforced composite (ADF).

Technical Effect

The present disclosure may provide the method to produce the unidirectionally-aligned discontinuous fiber-reinforced composite (ADF) using reinforcing short-fibers, and provide the unidirectionally-aligned discontinuous fiber-reinforced composite (ADF) produced using the method.

The sandwich structure according to the present disclosure may include the unidirectionally-aligned discontinuous fiber-reinforced composite (ADF) and thus have a high structural rigidity of the same level as that of a sandwich structure including a continuous fiber-reinforced composite is applied and have a higher design degree of freedom than that of the latter.

The effects of the present disclosure are not limited to those as mentioned above. Other effects as not mentioned will be clearly understood by those skilled in the art from descriptions of the claims.

