Conductive sheet and method for manufacturing resin molded product

Abstract

The present application provides a conductive sheet with good design. The conductive sheet (1) has: a base sheet (2); and a conductive wire (3) embedded in the upper surface of the base sheet. The base sheet includes a wire retaining portion (4) formed in a manner that protrudes from the upper surface along the edge portion (31, 32) of the conductive wire, and the width dimension W1 of the conductive wire: the width dimension W2 of the wire retaining portion = 1: (1.5-4.0).

Description

Technical Field

[0001] This invention relates to conductive sheets, and more particularly to conductive sheets for vehicle heaters, and a method for manufacturing resin molded articles using the conductive sheet. Background Technology

[0002] Japanese Patent Application Publication No. 2019-169417 (Patent Document 1) discloses a conductive sheet in which wires are embedded in the upper surface of a substrate sheet.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-169417 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] The conductive sheet in Patent Document 1 is formed by embedding wires during ultrasonic welding of a substrate sheet. However, no consideration is given to the appearance design at this time, resulting in problems such as distortion of the substrate sheet or whitening of the substrate sheet due to excessive embedding of the wires.

[0008] The present invention was made to solve the above-mentioned problems, and its purpose is to provide a conductive sheet that can improve the appearance design.

[0009] Solution for solving the problem

[0010] One embodiment of the present invention relates to a conductive sheet comprising: a substrate sheet; and a conductive wire embedded in the upper surface of the substrate sheet. The substrate sheet includes a wire holding portion formed such that it protrudes from the upper surface along the edge of the conductive wire. The width dimension W1 of the conductive wire and the width dimension W2 of the wire holding portion are 1: (1.5 to 4.0).

[0011] Preferably, the height position Y2 of the conductor holding part is lower than the height position Y1 of the conductive conductor.

[0012] Preferably, 40-75% of the height dimension H1 of the conductive wire is embedded in the substrate, with the upper surface of the substrate sheet as a reference.

[0013] Preferably, the tensile strength of the conductive wire is 200–600 N / mm².

[0014] A method for manufacturing a resin molded article according to one embodiment of the present invention includes: a step of preparing a conductive sheet, wherein the conductive sheet has a wire holding portion raised from the upper surface of a substrate sheet along the edge of a conductive wire, and the conductive wire is embedded in such a ratio as the width dimension W1 of the conductive wire to the width dimension W2 of the wire holding portion = 1:(1.5 to 4.0); a step of preparing an injection molding mold, wherein the injection molding mold has a fixed mold and a movable mold forming a cavity between the fixed mold and the fixed mold; a step of placing the conductive sheet on any cavity surface of the mold; a step of closing the injection molding mold; a step of injecting molten resin into the cavity to form a resin molded article and fixing the conductive sheet to the surface of the resin molded article; and a step of opening the injection molding mold and removing the resin molded article with the conductive sheet fixed thereon.

[0015] Another embodiment of the present invention relates to a method for manufacturing a resin molded article, comprising: a step of preparing a conductive sheet, wherein the conductive sheet has a wire holding portion raised from the upper surface of a substrate sheet along the edge of a conductive wire, and the conductive wire is embedded in such a ratio as the width dimension W1 of the conductive wire to the width dimension W2 of the wire holding portion = 1:(1.5 to 4.0); a step of preparing a resin molded body, wherein the resin molded body has a shape corresponding to the shape of the conductive sheet; and a step of fixing the resin molded body to the upper surface and / or lower surface of the conductive sheet.

[0016] The effects of the invention

[0017] According to the conductive sheet of the present invention, by appropriately embedding wires on the upper surface of the substrate sheet, it is possible to prevent the twisting of the upper surface of the substrate sheet and the detachment of the wires, thereby improving the appearance design. Attached Figure Description

[0018] Figure 1 This is a front view illustration of the conductive sheet involved in this embodiment.

[0019] Figure 2 This is a top view of the conductive sheet involved in this embodiment.

[0020] Figure 3 This is an explanatory diagram of an embodiment of the conductive sheet involved in this implementation.

[0021] Figure 4 This is a table showing various evaluations of the conductive sheets involved in Examples 1 to 9.

[0022] Figure 5 This is a table showing various evaluations of the conductive sheets involved in Comparative Examples 1 to 3.

[0023] Figure 6 This is a table showing the relationship between the wire embedding rate of the conductive sheet involved in Embodiment 10 and the width dimension of the wire holding portion.

[0024] Figure 7 (a) ~ Figure 7 (c) is a top view of the wire embedding portion of the conductive sheet involved in Embodiment 10. Detailed Implementation

[0025] Embodiments of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, in the drawings, the same or equivalent parts are labeled with the same reference numerals and will not be described again.

[0026] (Regarding composition)

[0027] Reference Figure 1 The conductive sheet 1 according to one embodiment of the present invention is described below. The conductive sheet 1 includes: a substrate sheet 2 with a rectangular shape when viewed from above; a conductive wire 3 embedded in the upper surface of the substrate sheet 2; and a wire holding portion 4 formed in such a way that it protrudes along the edge of the conductive wire 3. Figure 1 This is an explanatory diagram showing a cross-section of the conductive sheet 1 containing the conductive wire 3 from a front view. Additionally, [the following is a separate section:] Figure 1 , 2 The direction of arrow A1 shown is called the width direction of the conductor.

[0028] The substrate sheet 2 is formed from a thermoplastic resin, such as polycarbonate, polyethylene terephthalate, polyethylene naphthalate, polypropylene, PC-ABS, polyvinyl chloride, acrylic resin, etc. The substrate sheet 2 preferably has a heat shrinkage rate of 2.5% or less and possesses suitable ductility for use as a conductive film in injection molding. This not only improves moldability during injection molding but also prevents warping and deformation of the conductive sheet 1 during molding.

[0029] The substrate sheet 2 includes an upper surface 2a and a lower surface 2b, with conductive wires 3 embedded in the upper surface 2a. Any functional layer, such as an adhesive layer or a decorative layer, can be stacked on the lower surface 2b.

[0030] From the viewpoint of good formability, the thickness H3 of the substrate sheet 2 is preferably 0.2 mm to 0.8 mm. When it is thinner than 0.2 mm, the shape of the conductive pattern 3 will appear white on the back surface 2b of the sheet when the conductive pattern 3 is embedded in the substrate sheet 2, which may degrade the appearance design during molding. When it is thicker than 0.8 mm, molding may become difficult.

[0031] The conductive wire 3 is formed in an arbitrary pattern on the upper surface 2a of the substrate sheet. The pattern may be, for example, a meandering shape, a spiral shape, or a diagonal line shape. In this embodiment, the pattern is formed by a single wire, but two or more wires may also be used. Both ends of the conductive wire 3 are connected to terminals (not shown).

[0032] The conductive wire 3 can be appropriately selected from conductive materials such as copper, silver, lead, aluminum, nickel, beryllium, zirconium, etc., depending on the intended use and purpose of the molded product. That is, the conductive material can be only one type or an alloy containing two or more metals. In this embodiment, the conductive wire 3 is preferably made of a material with hardness and resistance value that takes into account the prevention of deformation during embedding and the ease with which the heater function can be performed, such as a silver-copper alloy.

[0033] The diameter of the conductive wire 3 is preferably 0.05 mm to 0.3 mm, more preferably 0.1 mm to 0.2 mm. When it is thinner than 0.05 mm, in addition to being prone to breakage, the heater function will also be reduced due to excessively high resistance. When it is thicker than 0.3 mm, the formed conductive sheet is prone to warping, and the forming process becomes cumbersome.

[0034] The conductive wire 3 is embedded by applying pressure or tension to the substrate sheet 2 and ultrasonic welding. Specifically, the wire embedding device (not shown) melts the upper surface 2a of the substrate sheet using ultrasound and delivers the conductive wire 3, applying pressure to the upper surface 2a of the substrate sheet 2 and embedding the wire. In top view, the two sides extending from the conductive wire 3 embedded in the substrate sheet 2 are referred to as the edges 31 and 32 of the wire.

[0035] The conductive wire 3 undergoes some deformation in its cross-sectional shape due to pressure or heat during embedding. Specifically, refer to... Figure 4 , 5 The photograph shows the upper surface of the conductor deformed flat. Therefore, the "diameter of the conductive conductor" mentioned above refers to the diameter before burial. After burial, the maximum dimensions in the height and width directions of its cross-section are recorded as "height dimension H1 of the conductive conductor" and "width dimension W1 of the conductive conductor".

[0036] From the viewpoint of preventing deformation during embedding, the tensile strength of the conductive wire 3 is preferably 200 to 600 N / mm², and more preferably 300 to 500 N / mm² from the viewpoint of preventing wire deformation and ensuring the stability of the embedding process. When the tensile strength is 600 N / mm² or higher, the conductive wire 3 becomes easier to peel off from the substrate sheet 2 because of the force (elastic force) that the conductive wire 3 tries to return to its original shape like a rebound spring. By using a conductive wire 3 with a specified tensile strength, the conductive sheet 1 of this embodiment can prevent wire breakage during embedding or twisting of the substrate sheet 2 due to excessive deformation of the wire.

[0037] Furthermore, from the viewpoint of preventing wire corrosion and enhancing adhesion to the substrate 2, the conductive wire 3 is preferably surrounded by a coating film (not shown). The coating film, for example, is a resin such as polyurethane, and serves to maintain the insulation of the conductive wire 3 in areas where no current is required. In this case, "wire diameter" refers only to the diameter of the conductive wire, while "conductive wire height" and "conductive wire width" refer to the height and width of the conductive wire including the coating film.

[0038] The conductor holding portion 4 includes a first conductor holding portion 41 on one side along the extension direction of the conductive conductor 3, and a second conductor holding portion 42 on the other side along the extension direction of the conductive conductor 3. The conductor holding portion 4 is formed by the substrate sheet 2 protruding upwards from the edges 31, 32 of the conductor during conductor embedding, and then, after elongating in the height direction, bending in a curved manner. Here, as... Figure 4 , 5 As can be observed in the photograph, the lead retainer is bent in such a way that an air layer 43 is formed on its inner side. Since the substrate sheet 2 will turn white when it contains air, this will significantly impair the appearance when used with molded articles featuring a black design. Therefore, the lead retainer 4 is preferably confined to the smallest possible area.

[0039] The height dimension H2 of the conductor holding portion is the height dimension H2 from the edge of the conductor to the top of the conductor holding portion in the height direction. Additionally, the width dimension W2 of the conductor holding portion includes the width dimension from the end of the first conductor holding portion 41 in the width direction to the end of the second conductor holding portion 42 in the width direction. Since the conductor holding portion 4 extends outward or inward towards the conductor in an upwardly curved manner, please note that the height dimension H2 and the width dimension W2 of the conductor holding portion are not necessarily the end faces of the conductor holding portion.

[0040] The height position Y1 of the conductive wire is the height position Y1 of the top end of the conductive wire 3 in the height direction. The height position Y2 of the wire holding part is the height position Y2 of the top end of the wire holding part in the height direction. In this embodiment, the height position Y2 of the wire holding part 4 is based on the relationship with the wire embedding device (not shown) provided above the conductive wire 3, and the height position Y1 of the wire becomes an upper limit value, that is, (height position Y1 of the wire) ≥ (height position Y2 of the wire holding part).

[0041] (Regarding size proportions)

[0042] The conductive sheet 1 of the present embodiment is formed such that the width dimension W1 of the conductive wire: the width dimension W2 of the wire holding portion = 1: (1.5 to 4.0). When W2 / W1 exceeds 4.0, the wire holding portion is in a state of being overly extended in the width direction, significantly damaging the appearance of the conductive sheet. When W2 / W1 is less than 1.5, the wire cannot be firmly held, and the wire is likely to peel off. From the perspective of design, it is more preferable that W1:W2 = 1: (1.5 to 3.5), and from the perspective of balancing design and preventing wire peeling, it is further preferable that W1:W2 = 1: (1.7 to 3.0).

[0043] The height position Y2 of the wire holding portion is preferably lower than the height position Y1 of the conductive wire and occupies more than 50% (0.5Y1 ≤ Y2 < Y1) of the height position Y1 of the conductive wire. Thus, since the wire holding performance is good and the wire holding portion 4 does not expand along the wire embedding device, good designability can be ensured.

[0044] For the conductive sheet 1 of the present embodiment, the height dimension H1 of the conductive wire: the thickness dimension H3 of the base material sheet = 1: (1.7 to 3.5). Since the base material sheet 2 of the conductive sheet 1 of the present embodiment has an appropriate thickness, it is not easily warped, and unevenness of the embedded wire is not formed on the back surface 2b of the base material sheet. Therefore, the designability of the conductive sheet 1 can be improved.

[0045] For the conductive wire 3 of the present embodiment, based on the upper surface 2a of the base material sheet 2, 40 to 75% of the height dimension H1 of the conductive wire is embedded in the base material sheet 2. Additionally, from the perspective of the designability of the conductive sheet, the wire embedding rate is more preferably 40 to 65%, and from the perspective of reliably preventing wire peeling, the wire embedding rate is further preferably 50 to 65%.

[0046] The wire holding portion 4 of the present embodiment is formed by bulging from the wire edge portion so as to push aside the upper surface 2a of the base material sheet when the conductive wire 3 is embedded. Here, when the wire embedding rate is less than 40%, the wire may peel off from the upper surface 2a of the base material sheet, damaging the designability. When the wire embedding rate is greater than 75%, when the conductive sheet is processed by injection molding, the wire holding portion 4 sometimes turns up and the conductive wire 3 is buried, damaging the designability. In contrast, the conductive sheet according to the present embodiment can release the volume of the wire holding portion 4 formed when the wire is embedded outward from the wire edge portion. Thereby, a conductive sheet 具有良好的导电性和设计性。

[0047] (Regarding Examples)

[0048] Next, refer to Figures 3-5 Examples 1 to 9 and Comparative Examples 1 to 3 of the conductive sheet 1 according to the present embodiment will be described as examples. Figure 3 This is an explanatory diagram of an embodiment of the conductive sheet involved in this implementation. Figure 4 This is a table showing various evaluation cross sections of the conductive sheets involved in Examples 1 to 9. Figure 5 This is a table showing various evaluations of the conductive sheets involved in Comparative Examples 1 to 3.

[0049] The substrate sheet used was Makrofol (registered trademark) DE1-4 polycarbonate sheet manufactured by Covestro, and the conductive wires were silver-containing copper wires (wire diameter 0.11 mm; sheath 0.01 mm; total diameter 0.12 mm). The conductive wires were embedded using a wire embedding device WCE150 manufactured by Ruhlamat.

[0050] Figure 3 The positions indicate the locations when the wires involved in Examples 1-9 and Comparative Examples 1-3 form a meandering pattern. Positions i and iv represent the central part of the straight area, positions ii and iii represent the ends of the straight area, and positions v and vi represent the ends of the curved area.

[0051] Figure 4 , 5 Various evaluation results are shown based on cross-sectional photographs of conductive wires patterned under the above conditions. Details of each evaluation item are as follows.

[0052] Position: Indicates the relationship with Figure 3 The corresponding position.

[0053] W2 / W1: This represents the value of the width dimension W2 of the conductor holding part and the width dimension W1 of the conductive conductor.

[0054] The relationship between Y1 and Y2: This indicates the relationship between the height position Y2 of the conductor holding part and the height position Y1 of the conductive conductor.

[0055] Embedment rate: This refers to the embedment rate of conductive wires relative to the upper surface of the substrate sheet.

[0056] Evaluation: The shapes of the conductive sheets in each embodiment are indicated by ◎, ○, and ×.

[0057] Photographs: SEM images of cross sections corresponding to the various embodiments and comparative examples.

[0058] Furthermore, the dimensions of the wire holding part (W2), the conductive wire (W1), the height position of the wire holding part (Y1), and the height position of the conductive wire (Y2) were measured by observing cross-sectional samples made from microsections.

[0059] Reference Figure 4The embedment rate of the conductive sheets in Examples 1-9 is 52.3%-73.2%, and the W2 / W1 ratio is 2.4-3.2. Based on these results, it can be seen that the conductive wires of Examples 1-9 maintain good wire holding force and have good aesthetic design. Furthermore, the W2 / W1 ratio of the conductive sheets in Examples 7-9 is 3.2, and compared with Examples 1-6, the expansion of the wire holding portion is visible. Therefore, the conductive sheets of Examples 7-9 are rated as 0 in terms of aesthetic design within acceptable limits, while the conductive sheets of Examples 1-6, which are considered the most preferred forms, are rated as ◎.

[0060] Reference Figure 5 The embedment rates of Comparative Examples 1-3 were 78.3%-90.9%, and the W2 / W1 ratio was 4 or higher. Based on these results, it can be seen that the conductive wires in Comparative Examples 1-3 were embedded deeper than in the Examples, and the wire holding portion was extended beyond the specified width, thus compromising the aesthetic design. Therefore, the appearance of the conductive sheets in Comparative Examples 1-3 was deemed undesirable and was rated as ×.

[0061] The embodiments and comparative examples involve extracting equivalent values ​​from patterned conductive wires under specified conditions. Figure 3 The evaluation is based on the positions described in the diagram. Typically, the wire embedding device moves quickly in the central portions i and iv of straight areas, and slowly in the ends ii, iii, v, and vi of curved areas. However, according to this embodiment, a conductive sheet with uniform wire embedding regardless of pattern position and good appearance design can be provided.

[0062] (Example 10)

[0063] Next, refer to Figure 6 , 7 Example 10 illustrates the conductive sheet of this embodiment. Figure 6 This is a table showing the relationship between the W2 / W1 ratio and the conductor embedment rate.

[0064] The substrate sheet used was Makrofol DE1-4 polycarbonate sheet manufactured by Covestro, and the conductive wires were silver-containing copper wires (total diameter 0.19 mm) manufactured by Electrosola. The conductive wires were embedded using a wire embedding device WCE150 manufactured by Ruhlamat.

[0065] Figure 6 The table shown is based on data obtained from wire embedding devices operating under various conditions to embed conductive wires in the aforementioned substrate sheet, summarizing data from which no wire stripping was found. Areas with a wire embedding rate of less than 50% are defined as "shallow" areas, areas of 50-65% are defined as "intermediate" areas, and areas of more than 65% are defined as "deep" areas.

[0066] according to Figure 6 The area indicated by arrow A is the "deep" region of conductor embedment rate, and W2 / W1 = (3.0~4.0). The area indicated by arrow B is the "intermediate" region of conductor embedment rate, and W2 / W1 = (1.7~3.5). The area indicated by arrow C is the "shallow" region of conductor embedment rate, and W2 / W1 = (1.5~2.0).

[0067] Figure 7 The photograph shows one of the conductive wires in each wire embedment area, taken from a top view. (a) is the deep area, where the wire retainer is observed to expand significantly in the lateral width direction. (b) is the intermediate area, and (c) is the shallow area, where, compared to the deep area, the expansion of the lateral width of the wire retainer is kept within acceptable limits. In particular, when using a black substrate, the wire retainer will turn white, indicating that a large lateral width of the wire retainer significantly detracts from the aesthetic design.

[0068] The conductive sheet 1 of this embodiment can embed a wire in a linear shape without twisting. Therefore, since the wire remains in the desired position, good electromagnetic wave transmission can be maintained. Furthermore, since the wire is prevented from being buried by the wire holding portion, conductivity and aesthetic design can be improved.

[0069] (Regarding the manufacturing method)

[0070] Next, a method for manufacturing the resin molded article according to this embodiment will be described. The resin molded article according to this embodiment is manufactured by injection molding a conductive sheet with embedded wires placed in a mold.

[0071] First, a conductive sheet is prepared, which has a conductor holding portion raised from the upper surface of a substrate sheet along the edge of a conductive wire, and the conductive wire is embedded in the conductive wire with a width W1 of the conductive wire : width W2 of the conductor holding portion = 1 : (1.5 to 4.0) (conductive sheet preparation step). Next, an injection molding mold is prepared, which has a fixed mold and a movable mold forming a cavity between the fixed mold and the fixed mold (mold preparation step). Next, the conductive sheet is placed on any cavity surface of the mold (placement step). Next, the injection molding mold is closed (mold closing step). Next, molten resin is injected into the cavity to form a resin molded body, while the conductive sheet is fixed to the surface of the resin molded body (fixing step). Next, the injection molding mold is opened, and the resin molded body with the conductive sheet fixed on it is removed (removal step). Thus, a resin molded article can be manufactured.

[0072] The conductive sheet can be fixed with a resin molded body on its upper and / or lower surfaces. The conductive wire 3 of this embodiment can also be further embedded during the fixing process. At this time, since the conductive sheet 1 is heated as a whole during injection molding and the mold is under high pressure, no further wire holding portion is formed.

[0073] Furthermore, a method for manufacturing a resin molded article according to another embodiment will be described. The resin molded article according to this embodiment is manufactured by bonding a conductive sheet with embedded wires to a resin molded body, for example, by injection molding.

[0074] First, a conductive sheet is prepared, which has a conductor holding portion that protrudes from the upper surface of a substrate sheet along the edge of a conductive wire, and the conductive wire is embedded in such a ratio that the width dimension W1 of the conductive wire : the width dimension W2 of the conductor holding portion = 1 : (1.5 to 4.0) (conductive sheet preparation step). Next, a resin molded body is prepared, which has a shape corresponding to the shape of the conductive sheet (resin molded body preparation step). The resin molded body is then fixed to the upper surface and / or lower surface of the conductive sheet (fixing step). Thus, a resin molded article can be manufactured.

[0075] Furthermore, in this embodiment, the wire holding part 4 is injection molded on the upper surface 2a of the conductive sheet. Sometimes, the air layer 43 formed inside the wire holding part 4 is filled with resin and becomes visually inconclusive.

[0076] Explanation of reference numerals in the attached figures

[0077] 1: Conductive sheet; 2: Substrate sheet; 3: Conductive wire; 4: Wire holding part; 31, 32: Wire edge; 41, 42: Wire holding part; 43: Air layer; W1: Width dimension of conductive wire; W2: Width dimension of wire holding part; H1: Height dimension of conductive wire; H2: Height dimension of wire holding part; H3: Thickness dimension of substrate sheet; Y1: Height position of conductive wire; Y2: Height position of wire holding part.

Claims

1. A conductive sheet, comprising: Substrate sheet; and Conductive wires are embedded in the upper surface of the substrate sheet. The substrate sheet includes a wire holding portion formed in such a way that it protrudes from the upper surface along the edge of the conductive wire. The width dimension W1 of the conductive wire and the width dimension W2 of the wire holding part are 1: (1.5~4.0).

2. The conductive sheet according to claim 1, wherein, The height position Y2 of the conductor holding part is lower than the height position Y1 of the conductive conductor.

3. The conductive sheet according to claim 1, wherein, With the upper surface of the substrate sheet as a reference, 40 to 75% of the height dimension H1 of the conductive wire is embedded in the substrate sheet.

4. The conductive sheet according to claim 1, wherein, The tensile strength of the conductive wire is 200–600 N / mm².

5. A method for manufacturing a resin molded article, comprising: In the process of preparing a conductive sheet, the conductive sheet has a conductor holding portion that protrudes from the upper surface of a substrate sheet along the edge of a conductive wire, and the conductive wire is embedded in such a ratio that the width dimension W1 of the conductive wire is equal to the width dimension W2 of the conductor holding portion as 1: (1.5 to 4.0). The process of preparing an injection molding mold, the injection molding mold having a fixed mold and a movable mold forming a cavity between the fixed mold and the movable mold; The process of placing the conductive sheet on any cavity surface of the mold; The process of closing the injection molding mold; The process of injecting molten resin into the cavity to form a resin molded body, while simultaneously fixing the conductive sheet to the surface of the resin molded body; and The process of opening the injection molding mold and removing the resin molded body with the conductive sheet attached.

6. A method for manufacturing a resin molded article, comprising: In the process of preparing a conductive sheet, the conductive sheet has a conductor holding portion that protrudes from the upper surface of a substrate sheet along the edge of a conductive wire, and the conductive wire is embedded in such a ratio that the width dimension W1 of the conductive wire is equal to the width dimension W2 of the conductor holding portion as 1: (1.5 to 4.0). The process of preparing a resin molded body, the resin molded body having a shape corresponding to the shape of the conductive sheet; and The process of fixing the resin molded body to the upper and / or lower surface of the conductive sheet.

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