Plated fibers and production method for plated fibers

Abstract

The present invention provides plated fibers having further improved heat resistance characteristics, and a production method for the plated fibers. A plated fiber 10 according to the present disclosure comprises a polyimide fiber 20 that is obtained as a result of slitting into narrow strips, and a plated metal film 30 that covers the polyimide fiber 20.

Description

Plated fibers and methods for manufacturing plated fibers

[0001] This disclosure relates to plated fibers and methods for manufacturing plated fibers.

[0002] Patent Document 1 discloses a method for manufacturing plated fibers, which includes a first step of applying a metal particle-containing polyester elastomer resin solution to the surface of an organic polymer fiber, a second step of drying the organic polymer fiber coated with the metal particle-containing polyester elastomer resin solution to form a sheath structure, and a third step of immersing the organic polymer fiber (core-sheath structure fiber) with the sheath structure formed by the drying process in an electroless plating solution at a temperature in the range of 40°C to 100°C to form a metal coating.

[0003] Furthermore, Patent Document 1 discloses that a specific example of the organic polymer fiber described is one or more fibers selected from nylon, polyester, and polypropylene.

[0004] Japanese Patent Publication No. 2017-52975

[0005] Plated fibers are expected to be used as the main material for functional fibers (fibers with various properties such as deodorizing, antiviral, heat retention, and water repellency) or as wiring for connecting to external electrodes, taking advantage of their electrical properties.

[0006] Here, the organic polymer fibers described in Patent Document 1, namely nylon, polyester, and polypropylene, have poor heat resistance and are highly likely to become brittle when heat is applied to the plated fibers.

[0007] This disclosure has been made in view of the above-mentioned problems. Specifically, the main purpose of this disclosure is to provide plated fibers with improved heat resistance and a method for manufacturing plated fibers.

[0008] The plated fiber according to this disclosure comprises a slit polyimide fiber and a plated metal film covering the polyimide fiber.

[0009] The method for manufacturing plated fibers according to this disclosure comprises a polyimide fiber forming step of slitting a polyimide film to form polyimide fibers, and a plating step of coating the polyimide fibers with a plated metal film.

[0010] According to this disclosure, since polyimide fibers, which have higher heat resistance than nylon, polyester, and polypropylene, are used, it is possible to provide plated fibers with improved heat resistance.

[0011] Figure 1 is a perspective view of the plated fiber of this disclosure. Figure 2 is a cross-sectional view of the plated fiber of this disclosure. Figure 3 is a graph showing the relationship between the tensile strength ratio and the aspect ratio AR. Figure 4 is a graph showing the relationship between the aspect ratio AR and the width of the plated fiber. Figure 5 is a flow chart showing the manufacturing flow of the plated fiber of this disclosure. Figure 6A is a cross-sectional view of the plated fiber before the process of forming the electroplated metal film. Figure 6B is a cross-sectional view of the plated fiber after the process of forming the electroplated metal film.

[0012] The plated fibers and methods for manufacturing the plated fibers described herein will be explained in detail below. While the explanation will be made with reference to the drawings as necessary, the illustrations are provided for illustrative purposes only to help understand this disclosure, and their appearance and dimensional ratios may differ from those of the actual product.

[0013] <Description of plated fiber> The plated fiber 10 of this disclosure comprises a narrowly slit polyimide fiber 20 and a plated metal film 30 covering the polyimide fiber 20. In this specification, "covering" means that the plated metal film 30 is completely covered by the polyimide fiber 20, but is not limited to a complete covering, and may be a covering of 90% or more of the surface of the polyimide fiber 20. The details of each component are described below.

[0014] - Polyimide Fibers The polyimide fibers 20 may be obtained by slitting a polyimide film. That is, the polyimide fibers 20 may be rectangular in shape, as shown in Figure 1. Here, in this specification, the slit width direction in which the polyimide film is slit is defined as the X direction, the thickness direction of the polyimide film is defined as the Y direction, and the direction perpendicular to the X and Y directions is defined as the Z direction. In this specification, "slit" means processing the film into a narrow width to form fibers. Furthermore, in this specification, "narrow width" means on the order of millimeters or less. More preferably, the slit width to be slit may be about 0.6 mm (corresponding to a fiber of 30 count) or less. Since the polyimide fibers 20 are slit into a narrow width, they may be flexible. In this specification, "flexibility" means the property of a material to bend flexibly under external force, and may mean that it is flexible and does not easily break when bent.

[0015] The polyimide used in the polyimide fiber 20 has higher heat resistance properties (e.g., melting point, coefficient of linear expansion, glass transition temperature) than conventional nylon, polyester, and polypropylene. Therefore, the plated fiber 10 using the polyimide fiber 20 can have improved heat resistance properties compared to the plated fiber using conventional nylon, polyester, and polypropylene.

[0016] As mentioned above, polyimide has high heat resistance. Therefore, it is difficult to use conventional extrusion molding methods, such as those used in the past, which involve melting fiber raw materials such as nylon, polyester, and polypropylene with heat and extruding them through a nozzle to form fibers. However, this disclosure employs a method of slitting the polyimide film into narrow strips. Therefore, even polyimide, which has high heat resistance, can be used as a fiber.

[0017] Furthermore, polyimide is more suitable as a substrate for plating compared to conventional materials such as nylon, polyester, and polypropylene. Therefore, the plating metal film 30 can be directly plated onto the polyimide fiber 20 without forming a sheath structure as in the conventional technology. Alternatively, the plating metal film 30 may be plated onto the polyimide fiber 20 after forming a sheath structure as in the conventional technology.

[0018] The plated metal film 30 is provided so as to cover the polyimide fibers 20. The metal constituting the plated metal film 30 may be selected from metal materials that can be electroless plated and electroplated. Examples include copper and / or nickel, silver, etc. This specification describes an embodiment in which copper is used for the plated metal film 30. Copper is a useful material in terms of conductivity, malleability, and cost.

[0019] The thickness of the plated metal film 30 is preferably 0.05 μm or more and / or 1 μm or less, from the viewpoint of completely covering the polyimide fiber 20 and / or durability.

[0020] As described above, the plated fiber 10 of this disclosure uses polyimide, which has higher heat resistance than nylon, polyester, and polypropylene, thus enabling the creation of a plated fiber 10 with improved heat resistance.

[0021] <Description of a suitable embodiment of the plated fiber> In the plated fiber 10 of this disclosure, the polyimide fiber 20 may be in contact with the plated metal film 30. Therefore, it is possible to reduce the number of manufacturing steps by suppressing the increase in manufacturing steps that form a sheath structure as in the prior art.

[0022] As a preferred embodiment of the plated fiber 10 of the present disclosure, as shown in Figure 2, when the slit width of the polyimide fiber 20 is X, the slit thickness of the polyimide fiber 20 is Y, and the aspect ratio of the polyimide fiber 20 is AR (=X / Y), then AR ≥ 51X ３ -29X ２ The ratio can be +7.4X + 0.47. This relationship between the aspect ratio AR and the slit width X is based on the graph in Figure 4. The relationship between the aspect ratio AR and the slit width X will be described in detail below.

[0023] In the plated fiber 10 of this disclosure, the narrowly slit polyimide fiber 20 may be affected by stress based on the tensile strength ratio, depending on the aspect ratio AR determined from the slit width X and thickness Y shown in Figure 2. Here, the "tensile strength ratio" as used herein refers to the ratio of the stress generated in the plated metal film 30 when the polyimide fiber 20 is bent to the tensile strength of the plated metal film 30 ("tensile strength ratio" = "stress generated in the plated film when the polyimide fiber is bent" / "tensile strength of the metal film"), and can be expressed as a function of the aspect ratio AR of the polyimide fiber 20 (see Figure 3 for the relationship between the tensile strength ratio and the aspect ratio AR). Here, the "tensile strength of the metal film" in the denominator of the formula is an intrinsic value determined by the material of the plated metal film 30 to be coated. The "stress generated in the plated film when the polyimide fiber is bent" in the numerator of the formula is a calculated value obtained by simulation using Femtet (Murata Software Co., Ltd.). Furthermore, this stress can also be estimated by, for example, forming a plating on a test thin piece and measuring its minute deflection.

[0024] In the plated fiber 10 of this disclosure, the tensile strength ratio is preferably 100% or less. That is, in Figure 3, it is preferable to use a polyimide fiber 20 with an aspect ratio AR such that the tensile strength ratio is 100% or less. By setting the aspect ratio AR such that the tensile strength ratio is 100% or less, the tensile strength of the plated metal film 30 becomes higher than that of the flexible polyimide fiber 20, thereby increasing the strength of the plated metal film 30. However, from the viewpoint of improving the heat resistance of the plated fiber 10, the tensile strength ratio may be 100% or more.

[0025] The graph shown in Figure 3 plots the relationship between the tensile strength ratio and the aspect ratio AR for three types of polyimide fibers 20 with slit widths X (see Figure 2) of 0.2 mm, 0.4 mm, and 0.6 mm. According to the graph in Figure 3, for the polyimide fiber 20 with a slit width X of 0.2 mm, the aspect ratio AR at which the tensile strength ratio is 100% was approximately 1.2. For the polyimide fiber 20 with a slit width X of 0.4 mm, the aspect ratio AR at which the tensile strength ratio is 100% was approximately 2.1. For the polyimide fiber 20 with a slit width X of 0.6 mm, the aspect ratio AR at which the tensile strength ratio is 100% was approximately 5.5. Therefore, according to the graph in Figure 3, when the polyimide fiber 20 has a slit width X of 0.2 mm, setting the aspect ratio AR to 1.2 or higher, when the polyimide fiber 20 has a slit width X of 0.4 mm, setting the aspect ratio AR to 2.1 or higher, and when the polyimide fiber 20 has a slit width X of 0.6 mm, setting the aspect ratio AR to 5.5 or higher results in a tensile strength ratio of 100% or less, thereby increasing the strength of the plated metal film 30.

[0026] Figure 4 shows a graph where the aspect ratio AR, which gives a tensile strength ratio of 100% as shown in Figure 3, has been rewritten to show its relationship with the slit width X. According to the graph in Figure 4, AR ≥ 51X ３ -29X ２ The tensile strength ratio may be 100% or less when the condition +7.4X + 0.47 is satisfied. Specifically, in the graph of Figure 4, substituting X = 0.2 gives an aspect ratio AR of approximately 1.2, substituting X = 0.4 gives an aspect ratio AR of approximately 2.1, and substituting X = 0.6 gives an aspect ratio AR of approximately 5.5. Therefore, AR ≥ 51X ３ -29X ２ When the formula +7.4X +0.47 is satisfied, the tensile strength ratio becomes 100% or less, and the strength of the plated metal film 30 can be increased.

[0027] As a suitable embodiment of the plated fiber 10, the polyimide fiber 20 may have a slit width of 0.6 mm or less and an aspect ratio AR of 5.6 or more. With such a configuration, as shown in Figure 3, even with thin fibers with a slit width of 0.6 mm or less, corresponding to fibers of 30 count (for example, slit widths of 0.2 mm or 0.4 mm in the graph of Figure 3), the tensile strength ratio becomes 100% or less, and the strength of the plated metal film 30 can be more preferably increased.

[0028] As a suitable embodiment of the plated fiber 10, the slit width of the polyimide fiber 20 may be 0.6 mm or less, and the aspect ratio AR may be 6 or more. With such a configuration, as shown in Figure 3, even with fine fibers with a slit width of 0.6 mm or less, which corresponds to fibers of 30 count (for example, slit widths of 0.2 mm or 0.4 mm in the graph of Figure 3), the tensile strength ratio becomes 100% or less, and the strength of the plated metal film 30 can be further preferably increased.

[0029] As a more preferable embodiment of the plated metal film 30 for the plated fiber 10, the plated metal film 30 may comprise an electroless plated metal film 31 in contact with the polyimide fiber 20 and an electroplated metal film 32 in contact with the electroless plated metal film 31 (see Figure 6B). In other words, the plated metal film 30 may have a film structure of at least two layers of different film types. In Figure 6A, which shows an example, if the plated metal film 30 consists only of an electroless plated metal film 31, the electroless plated metal film 31 is provided around the rectangular polyimide fiber 20, but there are areas where the plating film thickness is thin at the corners C of the rectangular parallelepiped. However, as shown in Figure 6B, if the plated metal film 30 comprises an electroless plated metal film 31 in contact with the polyimide fiber 20 and an electroplated metal film 32 in contact with the electroless plated metal film 31, the electroplated metal film 32 has high homogeneity and is easy to control the thickness of, so a plated film of sufficient thickness can be formed at the corners C of the rectangular parallelepiped.

[0030] Furthermore, in the plated metal film 30 described above, the electroplated metal film 32 may be a metal film with higher flatness than the electroless plated metal film 31. In this specification, "flatness" refers to an index obtained by dividing the surface roughness of the plated film by the plating film thickness (flatness = plating surface roughness (Ra) / plating film thickness), and the smaller this index related to flatness, the better the flatness. The surface roughness and plating film thickness of the plated film may be evaluated by observing the cross-section of the plated fiber with an SEM and using the SEM image (i.e., measurement of the plating surface roughness and plating film thickness). According to this embodiment of the plated metal film 30, the polyimide fiber 20 can be appropriately coated with two types of plated metal films 30 with different flatness.

[0031] <Explanation of the manufacturing method of plated fibers> Next, the manufacturing method of the plated fibers 10 of the present disclosure will be described. As shown in Figure 5, the manufacturing method of plated fibers of the present disclosure comprises a polyimide fiber formation step and a plating step. More preferably, a plating preparation step is included before the plating step. Furthermore, the plating step comprises a step of forming an electroless plated metal film and a step of forming an electroplated metal film. The following describes each step in detail.

[0032] • Polyimide Fiber Formation Process First, a polyimide film for forming the polyimide fibers 20 is prepared. As an example, a commonly available polyimide film with a thickness of 75 μm or a polyimide film with a thickness of 125 μm is prepared. Note that the thickness of the polyimide film is not limited to the above thicknesses.

[0033] The prepared polyimide film is slit to a narrow width to form polyimide fibers 20. As an example of a narrow width, it is preferable to use a width of 0.6 mm or less, which corresponds to a fiber of 30 count. More preferably, when the slit width of the polyimide fiber 20 is X, the slit thickness of the polyimide fiber 20 is Y, and the aspect ratio of the polyimide fiber 20 is AR (=X / Y), then AR ≥ 51X ３ -29X ２The equation +7.4X + 0.47 may be satisfied. When the above formula is satisfied, the tensile strength ratio of the plated fibers becomes lower than 100%, and the strength of the plated metal film 30 can be increased.

[0034] - In the plating preparation step, the polyimide fibers 20 formed are degreased to improve adhesion to the plating. Then, a catalyst, which is the core of the plating, is adsorbed onto them. In this way, by degreasing and adsorbing the catalyst onto the polyimide fibers 20 in the plating preparation step, which is a pre-processing step for the plating process, the adhesion of the plating in the plating process can be improved.

[0035] ・Plating process In the plating process, the polyimide fibers 20 are coated with a plating metal film. The plating metal film 30 may be selected from electroless plating and electroplatable metal materials. Examples include copper and / or nickel, silver, etc. Furthermore, the thickness of the plating metal film 30 is preferably 0.05 μm to 1 μm from the viewpoint of completely covering the polyimide fibers 20 and / or durability.

[0036] As an example of a suitable plating process, the plating process may include a step of applying electroless plating to the polyimide fiber 20 to form an electroless plated metal film 31, and a step of applying electroplating after the electroless plating to form an electroplated metal film 32 that comes into contact with the electroless plated metal film 31. In other words, the plated metal film 30 may have a film structure of at least two layers of different film types. By forming the electroplated metal film 32 after forming the electroless plated metal film 31 in this way, a plating film of sufficient thickness can be formed on the corners C of the rectangular parallelepiped in the polyimide fiber 20, as shown in Figure 6B.

[0037] As described above, the method for manufacturing the plated fiber 10 of this disclosure uses polyimide fiber 20, which has higher heat resistance than nylon, polyester, and polypropylene, making it possible to manufacture plated fiber 10 with even better heat resistance.

[0038] Note that the embodiments disclosed this time are illustrative in all respects and do not serve as a basis for a limiting interpretation. Therefore, the technical scope of the present disclosure is not interpreted only by the above-described embodiments, but is defined based on the description of the claims. Further, the technical scope of the present disclosure includes all changes within the meaning and scope equivalent to the claims.

[0039] The plated fiber and the method for manufacturing the plated fiber of the present disclosure include the following aspects. <1> A plated fiber comprising slit polyimide fibers and a plated metal film coating the polyimide fibers. <2> The plated fiber according to <1>, wherein the polyimide fiber is in contact with the plated metal film. <3> When the slit width of the polyimide fiber is X, the slit thickness of the polyimide fiber is Y, and the aspect ratio of the polyimide fiber is AR (= X / Y), AR ≥ 51X ３ -29X ２It is +7.4X + 0.47 or more, the plated fiber according to <1> or <2>. <4> The slit width of the polyimide fiber is 0.6 mm or less, and the aspect ratio is 5.6 or more, the plated fiber according to any one of <1> to <3>. <5> The slit width of the polyimide fiber is 0.6 mm or less, and the aspect ratio is 6 or more, the plated fiber according to any one of <1> to <3>. <6> The plated metal film includes an electroless plated metal film in contact with the polyimide fiber and an electrolytic plated metal film in contact with the electroless plated metal film, the plated fiber according to any one of <1> to <5>. <7> The electrolytic plated metal film is a metal film having high flatness with respect to the electroless plated metal film, the plated fiber according to <6>. <8> A polyimide fiber forming step of forming polyimide fibers by slitting a polyimide film, and a plating step of coating the polyimide fibers with a plated metal film, a method for manufacturing plated fibers. <9> After the polyimide fiber forming step, a plating preparation step of degreasing the polyimide fibers and adsorbing a catalyst to the degreased polyimide fibers, the method for manufacturing plated fibers according to <8>. <10> The plating step includes a step of performing electroless plating on the polyimide fibers to form an electroless plated metal film, and a step of performing electrolytic plating after the electroless plating to form an electrolytic plated metal film in contact with the electroless plated metal film, the method for manufacturing plated fibers according to <8> or <9>.

[0040] The plated fibers of the present disclosure can be suitably used as fibers with improved heat resistance characteristics.

[0041] 10 Plated fiber 20 Polyimide fiber 30 Plated metal film 31 Electroless plated metal film 32 Electrolytic plated metal film C Corner

Claims

1. A plated fiber comprising: a slit polyimide fiber; and a plated metal film covering the polyimide fiber.

2. The plated fiber according to claim 1, wherein the polyimide fiber is in contact with the plated metal film.

3. When the slit width of the polyimide fiber is X, the slit thickness of the polyimide fiber is Y, and the aspect ratio of the polyimide fiber is AR (=X / Y), then AR ≥ 51X ３ -29X ２ A plated fiber according to claim 1 or 2, wherein the coefficient of the product is +7.4X+0.47 or greater.

4. The plated fiber according to any one of claims 1 to 3, wherein the slit width of the polyimide fiber is 0.6 mm or less and the aspect ratio is 5.6 or more.

5. The plated fiber according to any one of claims 1 to 3, wherein the slit width of the polyimide fiber is 0.6 mm or less and the aspect ratio is 6 or more.

6. The plated metal film comprises an electroless plated metal film in contact with the polyimide fiber and an electroplated metal film in contact with the electroless plated metal film, the plated fiber according to any one of claims 1 to 5.

7. The plating fiber according to claim 6, wherein the electroplated metal film is a metal film with higher flatness than the electroless plated metal film.

8. A method for manufacturing plated fibers, comprising: a polyimide fiber forming step of slitting a polyimide film to form polyimide fibers; and a plating step of coating the polyimide fibers with a plated metal film.

9. A method for producing plated fibers according to claim 8, further comprising a plating preparation step of degreasing the polyimide fibers after the polyimide fiber formation step and adsorbing a catalyst onto the degreased polyimide fibers.

10. The method for manufacturing plated fibers according to claim 8 or 9, wherein the plating step comprises the steps of: applying electroless plating to the polyimide fiber to form an electroless plated metal film; and applying electroplating after the electroless plating to form an electroplated metal film that comes into contact with the electroless plated metal film.

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