Conductive film and conductive film manufacturing method

Abstract

The invention provides a conductive film and a method for manufacturing the conductive film. The resistance value can be suppressed even by a method other than an increase in the amount of conductive filler. The conductive film includes a resin, a conductive filler, and an antioxidant. The antioxidant inhibits at least oxidation of the resin. The antioxidant includes at least one of a phenolic antioxidant and a phosphite antioxidant.

Description

Technical Field

[0001] The present invention relates to a conductive film and a method for producing the conductive film. Background Art

[0002] Japanese Patent Publication No. 2019-179732 (Patent Document 1) discloses a conductive film comprising a crystalline olefin resin, a thermoplastic elastomer, and a conductive filler. Prior art literature

[0003] Patent Document 1: Japanese Patent Publication No. 2019-179732

[0004] In the conductive film disclosed in Patent Document 1, as a method of reducing the resistance value of the conductive film, a method of increasing the amount of conductive filler contained in the conductive film can be considered. However, if the amount of conductive filler contained in the conductive film is increased, the conductive film will become brittle. Summary of the invention

[0005] The present invention has been made to solve such a problem, and an object of the present invention is to provide a conductive film capable of reducing the resistance value even by a method other than increasing the amount of conductive filler, and a method for producing the conductive film.

[0006] The conductive film of one aspect of the present invention comprises a resin, a conductive filler, and an antioxidant. The antioxidant at least inhibits oxidation of the resin. The antioxidant comprises at least one of a phenolic antioxidant and a phosphite antioxidant.

[0007] The present inventors have found that the resistance value of the conductive film can be reduced by adding an antioxidant that inhibits the oxidation of the resin (e.g., a phenolic antioxidant and a phosphite antioxidant). The conductive film contains at least an antioxidant that inhibits the oxidation of the resin. Therefore, according to the conductive film, the resistance value can be reduced due to the antioxidant.

[0008] In the conductive film, a volume resistivity may be 100 Ω·cm or less.

[0009] In the conductive film, the antioxidant may be added in an amount of 0.1% to 0.5% by weight of the resin.

[0010] It can also be that the conductive film comprises: a first layer; and a second layer, which is stacked on the first layer, the resin includes a first resin and a second resin, the conductive filler includes a first conductive filler and a second conductive filler, the first layer contains the first resin and the first conductive filler, the second layer contains the second resin and the second conductive filler, and at least one of the first layer and the second layer contains an antioxidant.

[0011] According to this conductive film, since the antioxidant is contained in at least one of the first layer and the second layer, the resistance value can be reduced due to the antioxidant.

[0012] In the conductive film, the first conductive filler may be a carbon-based filler, and the second conductive filler may be a metal-based filler.

[0013] Another aspect of the present invention is a method for manufacturing a conductive film, comprising the following steps: a step of manufacturing a molten material by heating and melting a resin, a conductive filler and an antioxidant that at least inhibits oxidation of the resin; and a step of manufacturing a conductive film by extruding the molten material, wherein the antioxidant includes at least one of a phenolic antioxidant and a phosphite antioxidant.

[0014] In the method for producing the conductive film, an antioxidant for suppressing at least the oxidation of the resin is added during the production process of the conductive film. Therefore, according to the conductive film produced by the production method, the resistance value can be reduced due to the antioxidant.

[0015] According to the present invention, it is possible to provide a conductive film whose resistance value can be reduced even by a method other than increasing the amount of conductive filler, and a method for producing the conductive film. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a diagram schematically showing a cross section of the conductive film according to Embodiment 1. Figure 2 This is a diagram schematically showing the configuration of a conductive film manufacturing apparatus according to the first embodiment. Figure 3 This is a diagram schematically showing a cross section of a conductive film according to the second embodiment. Figure 4 This is a diagram schematically showing the configuration of a conductive film manufacturing apparatus according to the second embodiment. DETAILED DESCRIPTION

[0017] The following is a description of an embodiment of one aspect of the present invention (hereinafter also referred to as "this embodiment") with reference to the accompanying drawings. In addition, the same or corresponding parts in the figures are marked with the same reference numerals and their descriptions are not repeated. In addition, for easy understanding, each figure omits or exaggerates the schematic depiction of appropriate objects.

[0018] [1. Implementation Method 1] <1-1. Structure of conductive film> Figure 1Schematically showing a cross section of the conductive film 10 of the first embodiment. The conductive film 10 is used as a charge-carrying film, a charge-eliminating film, or various functional films for other electrical and electronic devices and parts, for example, a copier or printer. Figure 1 As shown, the conductive film 10 includes a first conductive resin layer 100 and a second conductive resin layer 200. The thickness T1 of the first conductive resin layer 100 is, for example, 1.5 to 5 times the thickness T2 of the second conductive resin layer 200. Each layer is described below.

[0019] (1-1-1. First Conductive Resin Layer) The first conductive resin layer 100 includes a resin and a conductive filler. An example of the resin is polyolefin. The first conductive resin layer 100 may further include an antioxidant. The antioxidant will be described in detail later.

[0020] Examples of polyolefins include polypropylene (PP) and polyethylene (PE). In addition, polymers containing α-olefins having 4 to 30 carbon atoms (such as 1-butene, isobutylene, 1-hexene, 1-decene, or 1-dodecene) as essential monomers may also be used as polyolefins. These polyolefins may be a single type or a mixture of two or more types.

[0021] Among polyolefins, polypropylene is preferred from the viewpoint of moisture-proof properties and mechanical strength. Examples of polypropylene include homopolypropylene, random polypropylene, block polypropylene, polypropylene having a long-chain branch structure, and acid-modified polypropylene.

[0022] As the conductive filler contained in the first conductive resin layer 100, a carbon filler can be cited. As the carbon filler, for example, graphite, carbon black (acetylene black, Ketjen black, furnace black, channel black, hot lamp black, etc.), carbon nanotubes, and mixtures thereof can be cited. Among the carbon fillers, carbon black is preferred, and acetylene black, furnace black, or mixtures thereof are more preferred.

[0023] (1-1-2. Second Conductive Resin Layer) The second conductive resin layer 200 is formed on the first conductive resin layer 100, and includes a first surface side layer 210 and a second surface side layer 220. The first surface 240 is the surface of the first conductive resin layer 100 opposite to the second conductive resin layer 200. The second surface 230 is the surface of the second conductive resin layer 200 opposite to the first conductive resin layer 100.

[0024] Each of the first surface side layer 210 and the second surface side layer 220 contains a resin and a conductive filler. As an example of the resin, polyolefin can be cited. As the polyolefin, for example, the polyolefin exemplified in the description of the first conductive resin layer 100 can be used. The second conductive resin layer 200 may further contain an antioxidant. The antioxidant will be described in detail later.

[0025] As the conductive filler contained in the second conductive resin layer 200, metal fillers such as platinum, gold, silver, copper, nickel, titanium and mixtures thereof can be cited. That is, the conductive filler contained in the second conductive resin layer 200 includes at least one metal element selected from platinum, gold, silver, copper, nickel and titanium. In addition, among these, nickel particles are more preferably used as the conductive filler. For example, in the second conductive resin layer 200, the second surface side layer 220 contains more conductive filler than the first surface side layer 210.

[0026] (1-1-3. Antioxidants) Generally, as a method for reducing the resistance value of a conductive film, a method of increasing the amount of conductive filler contained in the conductive film can be considered. However, if the amount of conductive filler contained in the conductive film is increased, problems such as the conductive film becoming brittle may occur.

[0027] The inventors have found that the resistance value of the conductive film can be suppressed by adding an antioxidant (e.g., a phenolic antioxidant and a phosphite antioxidant) that suppresses oxidation of the resin. In the conductive film 10 of the first embodiment, at least one of the first conductive resin layer 100 and the second conductive resin layer 200 contains at least one of a phenolic antioxidant and a phosphite antioxidant. Therefore, according to the conductive film 10, the resistance value can be reduced due to the antioxidant.

[0028] An example of the phenolic antioxidant is ADK STAB AO-60 manufactured by ADEKA Co., Ltd. The structure of ADK STAB AO-60 is shown below. [Chemistry 1]

[0029] The CAS registration number is "6683-19-8". The chemical name is "tetrakis[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionic acid]methane". The chemical formula is "C 73 H 108 O 12 ". The molecular weight is 1178.

[0030] Another example of the phenolic antioxidant is ADK STAB CDA-10 manufactured by ADEKA Co., Ltd. The structure of ADK STAB CDA-10 is shown below. [Chemistry 2]

[0031] The CAS registration number is "32687-78-8". The chemical name is "1,2-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hydrazine". The chemical formula is "C 34 H 52 N2O4". The molecular weight is 553.

[0032] An example of the phosphite antioxidant is ADK STAB HP-10 manufactured by ADEKA Co., Ltd. The structure of ADK STAB HP-10 is shown below. [Chemistry 3]

[0033] The CAS registration number is "126050-54-2". The chemical name is "2,2-methylenebis(4,6-di-tert-butylphenyl)octylphosphite". The chemical formula is "C 37 H 59 O3P". The molecular weight is 583.

[0034] For example, as an example of an antioxidant obtained by mixing a phenolic antioxidant and a phosphite antioxidant in advance, Irganox B225 and Irganox B215 manufactured by BASF Japan Ltd. In Irganox B225, the phenolic antioxidant and the phosphite antioxidant are mixed at a ratio of 1:1, whereas in Irganox B215, the phenolic antioxidant and the phosphite antioxidant are mixed at a ratio of 1:2.

[0035] The phenolic antioxidant contained in each of Irganox B225 and Irganox B215 is the same substance as ADK STABAO-60. The structure of the phosphite antioxidant contained in each of Irganox B225 and Irganox B215 is shown in the following formula. [Chemistry 4]

[0036] The CAS registration number of the phosphite antioxidant is "31570-04-4". The chemical name is "tris (2,4-di-tert-butylphenyl) phosphite". The chemical formula is "C 42 H 63O3P". The molecular weight is 647.

[0037] The amount of the antioxidant added to the first conductive resin layer 100 is, for example, 0.1% to 0.5% by weight of the resin contained in the first conductive resin layer 100. The amount of the antioxidant added to the second conductive resin layer 200 is, for example, 0.1% to 0.5% by weight of the resin contained in the second conductive resin layer 200.

[0038] The volume resistivity of the conductive film 10 containing an antioxidant in at least one of the first conductive resin layer 100 and the second conductive resin layer 200 is, for example, 100 Ω·cm or less. Also, the surface resistance of the conductive film 10 is 2000 Ω / □ or less.

[0039] <1-2. Method for producing conductive film> Figure 2 1 is a diagram schematically showing the structure of a manufacturing apparatus 40 for the conductive film 10 according to the first embodiment. The conductive film 10 is manufactured by the manufacturing apparatus 40. Figure 2 As shown, the manufacturing device 40 includes a T-die 400 , casting rollers 410 and 420 , and a take-up roller 430 .

[0040] The T-die 400 includes a T-die body 401 and raw material input parts 440, 450, and 460. The raw material for forming the second surface side layer 220 is input into the raw material input part 44. For example, polypropylene and nickel are input into the raw material input part 440. An antioxidant may be further input into the raw material input part 440.

[0041] The raw material for forming the first side layer 210 is fed into the raw material feeding section 450. For example, polypropylene and nickel are fed into the raw material feeding section 450. An antioxidant may be further fed into the raw material feeding section 450. The weight percentage concentration of nickel in the raw material fed into the raw material feeding section 450 is lower than the weight percentage concentration of nickel in the raw material fed into the raw material feeding section 440.

[0042] The raw material for forming the first conductive resin layer 100 is fed into the raw material feeding part 460. For example, polypropylene and carbon black are fed into the raw material feeding part 460. An antioxidant may be fed into the raw material feeding part 460 in addition.

[0043] The T-die body 401 is configured to co-extrude the raw materials input through the raw material input parts 440, 450, and 460, so that the melts of the raw materials input into each raw material input part are welded to each other to form an integrated film (molten material). The casting rolls 410 and 420 are configured to cool the extruded molten material and send the cooled molten material downstream. The winding roll 430 is configured to pull and wind up the cooled molten material passing through the casting rolls 410 and 420 at a predetermined speed. The winding body of the conductive film 10 is manufactured through the manufacturing process of the manufacturing device 40.

[0044] <1-3. Features> As described above, the antioxidant that at least suppresses the oxidation of the resin is contained in the conductive film 10 of the present embodiment 1. Therefore, according to the conductive film 10, it is possible to achieve a reduction in the resistance value due to the antioxidant.

[0045] [2. Implementation Method 2] The conductive film 10 of the first embodiment has a plurality of layers. However, the conductive film does not necessarily have to have a plurality of layers. For example, the conductive film may be composed of a single layer. The conductive film 10A of the second embodiment is composed of a single layer. The conductive film 10A will be described in detail below.

[0046] <2-1. Structure of conductive film> Figure 3 Schematically shows a cross section of the conductive film 10A according to the second embodiment. Figure 3 As shown, the conductive film 10A is composed of one conductive resin layer.

[0047] The conductive film 10A includes a resin, a conductive filler, and an antioxidant. As an example of the resin, polyolefin can be cited. As the polyolefin, for example, the polyolefin exemplified in the description of the first conductive resin layer 100 in the above embodiment 1 can be used. As an example of the conductive filler, a carbon filler and a metal filler can be cited. As the carbon filler, for example, the carbon filler exemplified in the description of the first conductive resin layer 100 in the above embodiment 1 can be used. As the metal filler, for example, the metal filler exemplified in the description of the second conductive resin layer 200 in the above embodiment 1 can be used.

[0048] Examples of antioxidants include phenolic antioxidants and phosphite antioxidants. As phenolic antioxidants and phosphite antioxidants, the substances exemplified in Embodiment 1 can be used. The conductive film 10A contains at least one of a phenolic antioxidant and a phosphite antioxidant.

[0049] <2-2. Method for producing conductive film> Figure 4Schematically shows the structure of a manufacturing apparatus 40A for a conductive film 10A according to the second embodiment. Figure 4 As shown, the manufacturing apparatus 40A includes a T-die 400A, casting rolls 410 and 420 , and a take-up roll 430 .

[0050] The T-die 400A is configured to heat and melt the resin, the conductive filler, and the antioxidant to produce a molten material, and extrude the molten material. The casting rolls 410 and 420 are configured to cool the extruded molten material and send the cooled molten material downstream. The winding roll 430 is configured to pull and wind up the cooled molten material passing through the casting rolls 410 and 420 at a predetermined speed. The winding body of the conductive film 10A is manufactured through the manufacturing process of the manufacturing device 40A.

[0051] <2-3. Features> As described above, the antioxidant that at least suppresses the oxidation of the resin is contained in the conductive film 10A of the second embodiment. Therefore, according to the conductive film 10A, it is possible to achieve a reduction in the resistance value due to the antioxidant.

[0052] [3. Other embodiments] The concept of the above-described embodiment is not limited to the above-described embodiment. Hereinafter, an example of another embodiment to which the concept of the above-described embodiment can be applied will be described.

[0053] <3-1> The conductive film may be composed of three or more layers, for example. The conductive film may be composed of a first layer comprising a resin (e.g., PP) and a metal filler (e.g., nickel), a second layer comprising a resin (e.g., PP) and a carbon filler (e.g., carbon black), and a third layer comprising a resin (e.g., PP) and a metal filler (e.g., nickel).

[0054] In addition, the conductive film may also be composed of a first layer comprising a resin (e.g., PP) and a carbon-based filler (e.g., carbon black), a second layer comprising a resin (e.g., PP) and a metal-based filler (e.g., nickel), and a third layer comprising a resin (e.g., PP) and a carbon-based filler (e.g., carbon black).

[0055] In addition, the conductive film may be composed of, for example, a first layer containing a resin (e.g., PP) and a carbon-based filler (e.g., carbon black), a second layer containing a resin (e.g., PP) and a carbon-based filler (e.g., carbon black), and a third layer containing a resin (e.g., PP) and a carbon-based filler (e.g., carbon black). In these cases, at least one of the first layer, the second layer, and the third layer may contain an antioxidant.

[0056] <3-2> In the case of a conductive film composed of two layers, the layer composition is not limited to the composition shown in the above embodiment 1. For example, the conductive film may be composed of a first layer containing a resin (e.g., PP) and a metal filler (e.g., nickel), and a second layer containing a resin (e.g., PP) and a metal filler (e.g., nickel). In this case, the weight percentage concentration of the metal filler may be different in the first layer and the second layer, and the type of at least one of the resin and the metal filler may be different in the first layer and the second layer.

[0057] In addition, the conductive film may be composed of, for example, a first layer including a resin (e.g., PP) and a carbon-based filler (e.g., carbon black), and a second layer including a resin (e.g., PP) and a carbon-based filler (e.g., carbon black). In this case, the weight percentage concentration of the carbon-based filler may be different in the first layer and the second layer, and the type of at least one of the resin and the carbon-based filler may be different in the first layer and the second layer.

[0058] The embodiments of the present invention are described above by way of example. That is, for the purpose of illustrative description, detailed description and drawings are disclosed. Therefore, the constituent elements recorded in the detailed description and drawings sometimes include constituent elements that are not necessary for solving the problem. Therefore, although these non-essential constituent elements are recorded in the detailed description and drawings, these non-essential constituent elements should not be directly identified as being essential.

[0059] In addition, the above-mentioned embodiment is merely an illustration of the present invention in all aspects. The above-mentioned embodiment can be variously improved and modified within the scope of the present invention. That is, when implementing the present invention, a specific configuration can be appropriately adopted according to the embodiment. [Example]

[0060] The following describes examples of the present invention. However, the present invention is not limited to the following examples.

[0061] [1. Examples and Comparative Examples] use Figure 2 The manufacturing apparatus 40 shown manufactured each conductive film of Examples 1-3 and Comparative Examples. Specifically, each conductive film of Examples 1-3 and Comparative Examples was manufactured by coextrusion. In each conductive film of Examples 1-3 and Comparative Examples, the second conductive resin layer 200 was formed of polypropylene and nickel, and the first conductive resin layer 100 was formed of polypropylene and carbon black. The film forming speed during the manufacture of each conductive film of Examples 1-3 and Comparative Examples was 2.5 m / min.

[0062] In each of the conductive films of Examples 1 to 3 and Comparative Example, the total thickness of the first conductive resin layer 100 and the second conductive resin layer 200 was 50 μm. The ratio of the thickness of the first conductive resin layer 100 to the thickness of the second conductive resin layer 200 was 3:1.

[0063] In each of the conductive films of Examples 1 to 3 and Comparative Example, the weight percent concentration of nickel in the second conductive resin layer 200 (each of the first-side layer 210 and the second-side layer 220) was 70 wt %, and the weight percent concentration of carbon black in the first conductive resin layer 100 was 30 wt %.

[0064] In the conductive film of Example 1, ADK STAB AO-60 and ADK STAB HP-10 manufactured by ADEKA Corporation are added to the second conductive resin layer 200. In the conductive film of Example 2, Irganox B225 manufactured by BASF Japan Co., Ltd. is added to the second conductive resin layer 200. In the conductive film of Example 3, Irganox B215 manufactured by BASF Japan Co., Ltd. is added to the second conductive resin layer 200. In the conductive film of the comparative example, no antioxidant is added. The amount of antioxidant added to each conductive film is shown in Table 1 below. The amount of each antioxidant added in Table 1 represents the ratio relative to the weight of the polypropylene contained in the second conductive resin layer 200. In Example 1, the amount of ADK STAB AO-60 added was 0.2% by weight of the PP of the second conductive resin layer 200 , and the amount of ADK STAB HP-10 added was 0.2% by weight of the PP of the second conductive resin layer 200 . [Table 1]

[0065] [2. Various measurements] <2-1. Measurement of volume resistivity> The volume resistivity of each conductive film of Examples 1 to 3 and Comparative Example was measured. Specifically, the volume resistivity of each conductive film was measured by the JISK 7194 method.

[0066] <2-2. Measurement of surface resistance> The surface resistance of each conductive film of Examples 1-3 and Comparative Examples was measured. Specifically, the surface resistance of each conductive film was measured using the following method. A 30 mm square test piece was cut and the surface resistance was measured using a simple low resistance meter Loresta AX MCP-T370 manufactured by Nittoseiko Analytech Co., Ltd. A PSP probe MCP-TP06P RMH112 was used as a probe. The value obtained by multiplying the resistance value (Ω) measured by the low resistance meter with the correction coefficient (4.532) was used as the surface resistance (Ω / □).

[0067] [3. Measurement results] The measurement results of each conductive film of Examples 1 to 3 and Comparative Example are shown in Table 2 below. [Table 2]

[0068] As shown in Table 2, the volume resistivity of each conductive film of Examples 1 to 3 is lower than that of the conductive film of Comparative Example, and the surface resistance of each conductive film of Examples 1 to 3 is lower than that of the conductive film of Comparative Example. Description of reference numerals:

[0069] 10, 10A: conductive film; 40, 40A: manufacturing device; 100: first conductive resin layer; 200: second conductive resin layer; 210: first surface side layer; 220: second surface side layer; 230: second surface; 240: first surface; 400, 400A: T-die; 401: T-die body; 410, 420: casting roller; 430: winding roller; 440, 450, 460: raw material input part.

Claims

1. A conductive film, characterized in that: The conductive film comprises: Resin; Conductive fillers; and an antioxidant, which at least inhibits oxidation of the resin, The antioxidant includes at least one of a phenolic antioxidant and a phosphite antioxidant.

2. The conductive film according to claim 1, wherein The volume resistivity is 100 Ω·cm or less.

3. The conductive film according to claim 1 or 2, characterized in that: The antioxidant is added in an amount of 0.1% to 0.5% by weight of the resin.

4. The conductive film according to any one of claims 1 to 3, characterized in that The conductive film comprises: First level; and A second layer, stacked on the first layer, The resin includes a first resin and a second resin, The conductive filler includes a first conductive filler and a second conductive filler, The first layer includes the first resin and the first conductive filler, The second layer includes the second resin and the second conductive filler, The antioxidant is contained in at least one of the first layer and the second layer.

5. The conductive film according to claim 4, characterized in that The first conductive filler is a carbon filler, The second conductive filler is a metal filler.

6. A method for producing a conductive film, characterized in that: The steps include: a step of preparing a molten material by heating and melting a resin, a conductive filler, and at least an antioxidant for suppressing oxidation of the resin; and a step of manufacturing a conductive film by extruding the molten material, The antioxidant includes at least one of a phenolic antioxidant and a phosphite antioxidant.

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