Joining method

Abstract

To provide a splicing method capable of suppressing separation from occurring during roll-to-roll splicing.SOLUTION: The tip of a diffusion layer base material unwound from an unwinding roll is sutured with the rear end of a heat-resistant sheet being wound up on the winding side roll using a flame-resistant thread.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to roll-to-roll splicing of materials. [Background technology]

[0002] Patent Document 1 discloses the use of adhesive tape as a method for joining two rolls of material together. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-175768 Summary of the Invention [Problem to be solved by the invention]

[0004] The roll-to-roll method is known, in which material is unwound from a roll, processed, and then wound up into a roll. In the roll-to-roll method, when the unwound roll is replaced with a new roll, the leading edge of the material unwound from the new roll is spliced ​​to the trailing edge of the material unwound from the old roll, allowing for continuous operation. Conventionally, double-sided tape or adhesive has been used for this splicing.

[0005] However, there has been a problem in that separation occurs at the joints, particularly when the treatment process involves heating in a baking furnace or the like.

[0006] In view of the above problems, an object of the present disclosure is to provide a method capable of suppressing separation during roll-to-roll splicing. [Means for solving the problem]

[0007] As a result of diligent research by the inventors, it was discovered that when the joint portion is heated in a baking furnace or the like, the adhesive strength of the double-sided tape or adhesive decreases, reducing the adhesive strength, which, combined with the tension during transportation, can cause the material to break or the materials at the double-sided tape or adhesive portion to separate (here, such breakage and separation are collectively referred to as "separation"). Based on this discovery, the inventors came up with the idea of ​​applying mechanical joining as a specific means for suppressing the occurrence of separation, and have embodied this idea.

[0008] The present application discloses a joining method in which the leading end of the diffusion layer substrate unwound from the unwinding roll and the trailing end of the heat-resistant sheet being wound onto the winding roll are sewn together with a flame-resistant thread. [Effects of the Invention]

[0009] According to the method of the present disclosure, the occurrence of separation at the joint can be suppressed by sewing the joint and mechanically joining it. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating an outline of the production of a gas diffusion layer by roll-to-roll method. [Figure 2] FIG. 2 is a diagram illustrating the configuration of the joint portion. DETAILED DESCRIPTION OF THE INVENTION

[0011] 1. Roll-to-roll process flow The process flow for roll-to-roll fabrication is shown schematically in Figure 1 (a) to (d). In this roll-to-roll fabrication, a gas diffusion layer, which is one layer belonging to a power generation unit cell of a fuel cell composed of multiple layers, is fabricated. A composition that will become the microporous layer (MPL) 3 is applied to the diffusion layer substrate 1 unwound from the unwinding roll 11, and the composition is then heated and dried before being wound up on the winding roll 12 as a laminate 4. In roll-to-roll operation, the unwinding roll 11 and the take-up roll 12 need to be replaced, but for continuous operation, the leading end 11b of the material unwound from the replaced unwinding roll 11 and the tail end 12b of the material wound around the take-up roll 12 are joined together to form a spliced ​​portion 15. More specifically, this is as follows.

[0012] 1.1. Formation of laminate Figure 1(a) shows a scene in which a strip-shaped diffusion layer substrate 1 is unwound from an unwinding roll 11, a composition that becomes MPL3 is applied to the diffusion layer substrate 1 from an application device 13, and the diffusion layer substrate 1 is heated and dried in a firing furnace 14 to form a laminate 4 in which MPL3 is formed on the diffusion layer substrate 1, which is then wound up on a winding roll 12. The conditions for this step are not particularly limited, but for example, the material is conveyed at a speed of 2 m / min to 30 m / min, and the tension applied to the material during conveyance is 20 N to 180 N.

[0013] [Unwinding roll] The unwinding roll 11 is a roll in which the strip-shaped diffusion layer substrate 1 is wound around a core material 11 a and from which the diffusion layer substrate 1 is successively unwound to form the laminate 4 . The diffusion layer substrate 1 is a material that serves as the base material for the gas diffusion layer that constitutes one layer of the power generation unit cell of the fuel cell, and is, for example, a conductive porous body. More specific examples include porous carbon bodies (carbon paper, carbon cloth, glassy carbon, etc.) and porous metal bodies (metal mesh, metal foam). The size of the strip-shaped diffusion layer substrate 1 is not particularly limited, but is generally 100 mm to 500 mm wide, 10 μm to 500 μm thick, and 100 m to 1000 m long. Furthermore, the center side of the unwinding roll 11 (the position where it is unwound last) is not the diffusion layer substrate 1 but the heat-resistant sheet 2 connected to the diffusion layer substrate 1 so as to be continuous with it. The heat-resistant sheet 2 is made of a material that does not break or deform much even when heated in the baking furnace 14 (200°C to 420°C in this embodiment). In this embodiment, it is a polyimide sheet. There are no particular limitations on the size of the heat-resistant sheet 2, but it is preferable that the width is approximately the same as that of the diffusion layer substrate 1, the thickness is 10 μm to 500 μm, and the length is 1 m to 100 m.

[0014] [Take-up roll] The take-up roll 12 is a roll around which the laminate 4 is wound around the core material 12a. As will be described later, the heat-resistant sheet 2 is first wound around the take-up roll 12, and then the laminate 4 is wound around it after passing through the joint section 15. Therefore, the take-up roll 12 finally becomes a roll in which the heat-resistant sheet 2 is wound on the core material 12a side (center side) and the laminate 4 is wound around the outside of that.

[0015] [Formation of MPL] As described above, MPL3 is laminated on the diffusion layer substrate 1 to form the laminate 4. MPL3 is a thin coating applied to one side of the diffusion layer substrate 1. MPL3 has water repellency or hydrophilicity as needed, allowing it to regulate moisture. MPL3 is typically made of a material whose main components are a water-repellent resin such as polytetrafluoroethylene (PTFE) and a conductive material such as carbon black. The formation of MPL 3 is known, but in this embodiment, a paste-like composition is supplied from an application device 13 to the diffusion layer substrate 1, and is heated and dried at 200°C to 420°C in a baking furnace .

[0016] 1.2.Completion of unwinding As described above, the diffusion layer substrate 1 is unwound from the unwinding roll 11, the MPL 3 is formed into the laminate 4, and the winding by the winding roll 12 proceeds, and when unwinding from the unwinding roll 11 is completed, the process is temporarily stopped. In this embodiment, as described above, the heat-resistant sheet 2 is the last to be unwound from the unwinding roll 11, so when the unwinding roll 11 finishes unwinding and pauses, the heat-resistant sheet 2 is placed between the unwinding roll 11 and the take-up roll 12 (pass line) as shown in Figure 1(b). The material of the diffusion layer substrate 1 is expensive, and if it is overheated while stopped in the firing furnace 14, its performance will deteriorate. Therefore, by discharging the entire equipment pass line with the heat-resistant sheet 2 in this way, waste of the diffusion layer substrate 1 can be reduced.

[0017] 1.3.Replacing the take-up roll Next, as shown in FIG. 1(c), the take-up roll 12 is replaced, and the leading end of the heat-resistant sheet 2 arranged on the pass line is fixed to the core material 12a.

[0018] 1.4.Cutting the heat-resistant sheet As shown in Figure 1(d), the heat-resistant sheet 2 arranged on the pass line is cut at a position between the unwinding roll 11 and the coating device 13. As a result, a rear end portion 12b of the material is formed on the heat-resistant sheet 2 connected to the winding roll 12. The position where the rear end portion 12b of the material is placed may be at least closer to the unwinding roll 11 than the firing furnace 14, but from the viewpoint of utilizing the diffusion substrate 1 without waste, it is preferable that it be closer to the unwinding roll 11 than the coating device 13.

[0019] 1.5.Installation of the unwinding roll Next, as shown in Figure 1(e), a new unwinding roll 11 is placed and the material leading end 11b, which is the leading end of the diffusion layer substrate 1, is joined to the material trailing end 12b formed above to form a joint 15. The structure of the joint 15 will be described later. Thereafter, the unwinding roll 11 and the winding roll 12 are driven to rotate, and the roll-to-roll process is resumed as shown in FIG. 1(a).

[0020] 2. Joint As described above, in this embodiment, the rear end 12b of the material of the heat-resistant sheet 2 connected to the take-up roll 12 and the leading end 11b of the material, which is the leading end of the diffusion layer substrate 1 of the unwinding roll 11, are joined together to form the spliced ​​portion 15. The spliced ​​portion 15 will be described in detail below. Fig. 2 shows an explanatory diagram of the spliced ​​portion 15. Fig. 2(a) is a plan view of the spliced ​​portion 15 (viewed from the direction of arrow A in Fig. 1(e)), and Fig. 2(b) is a view of the spliced ​​portion 15 from the same perspective as Fig. 1(e) (however, for ease of understanding, the thread 17a is shown in perspective).

[0021] As can be seen from Figure 2, at the joint 15, in a plan view (viewpoint of Figure 2(a)), the diffusion layer substrate 1 is positioned on the bottom and the heat-resistant sheet 2 is positioned on the top so that their ends overlap, and a reinforcing material 16 is disposed between the diffusion layer substrate 1 and the heat-resistant sheet 2 at the overlapping portion. Furthermore, in this embodiment, a reinforcing material 16 is also disposed on the surface of the heat-resistant sheet 2 opposite to the side facing the diffusion layer substrate 1. Although not disposed in this embodiment, a reinforcing material may be disposed on the surface of the diffusion layer substrate 1 opposite to the side facing the heat-resistant sheet 2.

[0022] Here, the degree of overlap between the diffusion layer substrate 1 and the heat-resistant sheet 2, indicated by B in FIG. 2(b), is preferably 10 mm to 200 mm.

[0023] The material of the reinforcing material 16 is not particularly limited as long as it has a predetermined strength, but examples thereof include a polyimide sheet (including the same material as the heat-resistant sheet 2), a polyimide tape, and a glass cloth. The thickness of the reinforcing material 16 is not particularly limited, but is preferably 10 μm to 100 μm. Furthermore, the reinforcing material 16 may be a stack of multiple thin pieces, or a single thick piece.

[0024] Furthermore, the diffusion layer substrate 1, the heat-resistant sheet 2, and the reinforcing material 16 are sewn together at the joint 15 with a thread 17a. Specifically, the thread 17a is sewn back and forth through these in the thickness direction while extending offset in the width direction of the diffusion layer substrate 1 and the heat-resistant sheet 2 (a direction perpendicular to the direction in which the pass line extends), forming the sewn portion 17. The thread 17a is not particularly limited, but is preferably a heat-resistant, so-called flame-resistant thread, more specifically, a thread made of aramid fiber. The thickness of the thread is also not particularly limited, but is preferably in the range of count 0 to 100.

[0025] The stitching pitch (the size of one of the multiple thread portions appearing on one surface in the thickness direction) shown in Figure 2(a) is not particularly limited, but is preferably greater than 7 mm and less than 20 mm.

[0026] In addition, the number of rows of stitching (the number of sewn portions aligned in the pass line direction) is two (two rows) in this embodiment as can be seen from Figure 2, but it is not limited to this and may be one (one row) or three or more (three rows or more). The greater the number of rows, the greater the effect of suppressing separation.

[0027] 3. Effects etc. By configuring the joint portion 15 as described above, separation of the two parts at the jointed portion can be prevented even when a heating process is involved, and continuous production can be carried out efficiently.

[0028] 4. Working Example In the examples, the number of stitching rows, the number of reinforcing materials, the stitching pitch (P in Figure 2(a)), the baking oven temperature, and the tension were changed based on the example of the joint 15, and the tension at which the joint separated was investigated. The materials used in this example are as follows. Diffusion layer substrate: carbon paper, thickness 50μm~500μm, width 300mm MPL coating liquid: porous carbon material Heat-resistant sheet: Polyimide sheet, thickness 50 μm, width 300 mm Reinforcement: Polyimide sheet, 25 μm thick Flame-resistant thread: Aramid fiber, thread thickness 30 count Overlap size: See Table 1

[0029] Using the above materials, a joint was formed as shown in Table 1 following the example in Figure 2, and then the unwinding of the material by the unwinding roll 11 and the winding of the material by the winding roll 12 were started from the state shown in Figure 1(e). The temperature of the firing furnace at this time is shown in Table 1. In addition, in Table 1, "number of reinforcing materials" means the number of reinforcing materials arranged at each of the positions shown in Figure 2(b). The conveying tension was changed in each test, and the tension at which the material broke (breaking tension) was investigated. The results are shown in Table 1. Here, the breaking tension is expressed as the force applied to a 300 mm wide material in [N / 300 mm].

[0030] [Table 1]

[0031] As described above, the joining method of the present disclosure can suppress separation problems caused by the heating process compared to joining using adhesive tape. [Explanation of symbols]

[0032] 1. Diffusion layer substrate 2 Heat-resistant sheet 3 MPL (microporous layer) 4 Laminate 11 Unwinding roll 12 Take-up roll 13 Coating equipment 14 Kiln 15 Joint 16 Reinforcement 17 Suture area

Claims

[Claim 1] a leading end of the strip-shaped diffusion layer substrate unwound from a winding-side roll, a trailing end of the heat-resistant sheet wound onto a winding-side roll, and a reinforcing material disposed between the leading end of the diffusion layer substrate and the trailing end of the heat-resistant sheet are sewn together with a flame-resistant thread extending in the width direction of the diffusion layer substrate while reciprocating so as to penetrate the diffusion layer substrate, the reinforcing material, and the heat-resistant sheet in the thickness direction; Splicing method.

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