Conductive film, and method for manufacturing conductive film

Abstract

To provide a conductive film in which an electric resistance value is suppressed even by a method other than increase in an amount of a conductive filler, and a method for manufacturing the conductive film.SOLUTION: A conductive film contains a resin, a conductive filler, and an antioxidant. The antioxidant suppresses at least oxidation of a resin. The antioxidant contains at least one of a phenolic antioxidant and a phosphite-based antioxidant.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a conductive film and a method for manufacturing a conductive film. [Background technology]

[0002] JP 2019-179732 A (Patent Document 1) discloses a conductive film. This conductive film contains a crystalline olefin resin, a thermoplastic elastomer, and a conductive filler. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-179732 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the conductive film disclosed in Patent Document 1, a method of increasing the amount of conductive filler contained in the conductive film can be considered as a method for reducing the electrical resistance of the conductive film. However, when the amount of conductive filler contained in the conductive film is increased, problems such as the conductive film becoming brittle occur.

[0005] The present invention has been made to solve such problems, and its object is to provide a conductive film that is capable of reducing the electrical resistance value by methods other than increasing the amount of conductive filler, and a method for manufacturing said conductive film. [Means for solving the problem]

[0006] A conductive film according to an aspect of the present invention includes a resin, a conductive filler, and an antioxidant. The antioxidant suppresses oxidation of at least the resin. The antioxidant includes at least one of a phenol-based antioxidant and a phosphite-based antioxidant.

[0007] The present inventor(s) discovered that the electrical resistance value of the conductive film is reduced by adding an antioxidant (e.g., a phenol-based antioxidant and a phosphite-based antioxidant) that suppresses the oxidation of the resin. This conductive film contains at least an antioxidant that suppresses the oxidation of the resin. Therefore, this conductive film can achieve a reduction in electrical resistance value due to the antioxidant.

[0008] The conductive film may have a volume resistivity of 100 Ω·cm or less.

[0009] In the conductive film, the amount of the antioxidant added may be 0.1% or more and 0.5% or less by weight of the resin.

[0010] The conductive film may include a first layer and a second layer laminated to the first layer, the resin may include a first resin and a second resin, the conductive filler may include a first conductive filler and a second conductive filler, the first layer may include the first resin and the first conductive filler, the second layer may include the second resin and the second conductive filler, and an antioxidant may be included in at least one of the first layer and the second layer.

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

[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] A method for producing a conductive film according to another aspect of the present invention includes the steps of producing a molten material by heating and melting a resin, a conductive filler, and an antioxidant that at least suppresses oxidation of the resin, and producing a conductive film by extruding the molten material, wherein the antioxidant includes at least one of a phenol-based antioxidant and a phosphite-based antioxidant.

[0014] In this method for producing a conductive film, an antioxidant that suppresses oxidation of at least the resin is added during the production process of the conductive film, and therefore, the conductive film produced by this method can achieve a reduced electrical resistance value due to the antioxidant. Effect of the Invention

[0015] According to the present invention, it is possible to provide a conductive film in which the electrical resistance value can be reduced 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] 1 is a schematic cross-sectional view of a conductive film according to a first embodiment. FIG. [Diagram 2] FIG. 1 is a diagram illustrating a schematic configuration of a conductive film manufacturing apparatus according to a first embodiment. [Diagram 3] FIG. 11 is a schematic cross-sectional view of a conductive film according to a second embodiment. [Figure 4] FIG. 11 is a diagram illustrating a schematic configuration of a conductive film manufacturing apparatus according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment according to one aspect of the present invention (hereinafter also referred to as "the present embodiment") will be described in detail with reference to the drawings. Note that the same or corresponding parts in the drawings are given the same reference numerals and their description will not be repeated. Also, each drawing is drawn in a schematic manner with objects appropriately omitted or exaggerated for ease of understanding.

[0018] [1. Embodiment 1] <1-1. Structure of conductive film> FIG. 1 is a schematic diagram showing a cross section of a conductive film 10 according to the first embodiment. The conductive film 10 is used, for example, as a charging film or a discharging film for a copier or a printer, or as various functional films for electric / electronic devices and components. As shown in FIG. 1, 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 times or more and 5 times or less the thickness T2 of the second conductive resin layer 200. Each layer will be described below.

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

[0020] Examples of polyolefins include polypropylene (PP) and polyethylene (PE). In addition, polymers containing an α-olefin having 4 to 30 carbon atoms (1-butene, isobutene, 1-hexene, 1-decene, 1-dodecene, etc.) as an essential constituent monomer may be used as the polyolefin. These polyolefins may be used alone or in the form of a mixture of two or more kinds.

[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 branched structure, and acid-modified polypropylene.

[0022] The conductive filler contained in the first conductive resin layer 100 may be a carbon-based filler. Examples of the carbon-based filler include graphite, carbon black (acetylene black, ketjen black, furnace black, channel black, thermal lamp black, etc.), carbon nanotubes, and mixtures thereof. Among the carbon-based 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. An example of the resin is 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] Examples of the conductive filler contained in the second conductive resin layer 200 include metal-based fillers such as platinum, gold, silver, copper, nickel, titanium, and mixtures thereof. That is, the conductive filler contained in the second conductive resin layer 200 includes at least one metal element selected from the group including platinum, gold, silver, copper, nickel, and titanium. Among these, nickel particles are more preferable as the conductive filler. For example, in the second conductive resin layer 200, the conductive filler is contained more in the second surface side layer 220 than in the first surface side layer 210.

[0026] (1-1-3. Antioxidants) In general, a method for reducing the electrical resistance of a conductive film is to increase the amount of conductive filler contained in the conductive film, but increasing the amount of conductive filler contained in the conductive film can cause problems such as making the conductive film brittle.

[0027] The present inventor(s) found that the electrical resistance value of the conductive film can be suppressed by adding an antioxidant (e.g., a phenol-based antioxidant and a phosphite-based antioxidant) that suppresses oxidation of the resin. In the conductive film 10 according to 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 phenol-based antioxidant and a phosphite-based antioxidant. Therefore, with the conductive film 10, a reduction in electrical resistance value due to the antioxidant can be realized.

[0028] An example of the phenol-based antioxidant is ADK STAB AO-60 manufactured by ADEKA Corp. The structure of ADK STAB AO-60 is shown in the following formula. [ka]

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

[0030] Another example of the phenol-based antioxidant is ADK STAB CDA-10 manufactured by ADEKA Corp. The structure of ADK STAB CDA-10 is shown in the following formula. [ka]

[0031] The CAS 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-based antioxidant is ADK STAB HP-10 manufactured by ADEKA Corp. The structure of ADK STAB HP-10 is shown in the following formula. [ka]

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

[0034] For example, examples of antioxidants in which a phenolic antioxidant and a phosphite antioxidant are pre-blended include Irganox B225 and Irganox B215 manufactured by BASF Japan Ltd. In Irganox B225, a phenolic antioxidant and a phosphite antioxidant are blended in a ratio of 1:1, whereas in Irganox B215, a phenolic antioxidant and a phosphite antioxidant are blended in a ratio of 1:2.

[0035] The phenol-based antioxidant contained in each of Irganox B225 and Irganox B215 is the same substance as that contained in ADK STAB AO-60. The structure of the phosphite-based antioxidant contained in each of Irganox B225 and Irganox B215 is as shown in the following formula. [ka]

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

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

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

[0039] <1-2. Manufacturing method of conductive film> 2 is a diagram illustrating a schematic configuration of a manufacturing apparatus 40 for the conductive film 10 according to the present embodiment 1. The conductive film 10 is manufactured by the manufacturing apparatus 40. As shown in FIG. 2, the manufacturing apparatus 40 includes a T-die 400, casting rolls 410 and 420, and a take-up roll 430.

[0040] The T-die 400 includes a T-die main body 401 and raw material input sections 440, 450, and 460. Raw materials for forming the second surface side layer 220 are input into the raw material input section 440. For example, polypropylene and nickel are input into the raw material input section 440. An antioxidant may also be input into the raw material input section 440.

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

[0042] Raw materials for forming the first conductive resin layer 100 are input into the raw material input section 460. For example, polypropylene and carbon black are input into the raw material input section 460. An antioxidant may also be input into the raw material input section 460.

[0043] The T-die body 401 is configured to co-extrude the raw materials fed through the raw material feed sections 440, 450, and 460, thereby fusing the molten raw materials fed into each raw material feed section to form a single integrated film (molten material). The casting rolls 410 and 420 are configured to cool the extruded molten material and send it downstream. The winding roll 430 is configured to pull and wind the molten material cooled by the casting rolls 410 and 420 at a predetermined speed. A roll of conductive film 10 is manufactured through the manufacturing process in the manufacturing apparatus 40.

[0044] <1-3.Features> As described above, the conductive film 10 according to the first embodiment contains at least an antioxidant that suppresses oxidation of the resin. Therefore, the conductive film 10 can achieve a reduction in electrical resistance due to the antioxidant.

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

[0046] <2-1. Structure of conductive film> Fig. 3 is a schematic cross-sectional view of a conductive film 10A according to the present embodiment 2. As shown in Fig. 3, 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. An example of the resin is polyolefin. For example, the polyolefin may be one exemplified in the description of the first conductive resin layer 100 in the above-mentioned first embodiment. For example, the conductive filler may be a carbon-based filler or a metal-based filler. For example, the carbon-based filler may be one exemplified in the description of the first conductive resin layer 100 in the above-mentioned first embodiment. For example, the metal-based filler may be one exemplified in the description of the second conductive resin layer 200 in the above-mentioned first embodiment.

[0048] Examples of the antioxidant include a phenol-based antioxidant and a phosphite-based antioxidant. As the phenol-based antioxidant and the phosphite-based antioxidant, those exemplified in the above-mentioned embodiment 1 can be used. The conductive film 10A contains at least one of a phenol-based antioxidant and a phosphite-based antioxidant.

[0049] <2-2. Manufacturing method of conductive film> 4 is a diagram illustrating a schematic configuration of a manufacturing apparatus 40A for the conductive film 10A according to the present embodiment 2. As shown in FIG. 4, 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 produce a molten material by heating and melting the resin, the conductive filler, and the antioxidant, and to extrude the molten material. The casting rolls 410 and 420 are configured to cool the extruded molten material and send it downstream. The winding roll 430 is configured to pull and wind the molten material cooled by the casting rolls 410 and 420 at a predetermined speed. A roll of the conductive film 10A is produced through the manufacturing process in the manufacturing apparatus 40A.

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

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

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

[0054] The conductive film may also be composed of, for example, a first layer including a resin (e.g., PP) and a carbon-based filler (e.g., carbon black), a second layer including a resin (e.g., PP) and a metal-based filler (e.g., nickel), and a third layer including a resin (e.g., PP) and a carbon-based filler (e.g., carbon black).

[0055] 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, it is sufficient that at least one of the first layer, the second layer, and the third layer contains an antioxidant.

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

[0057] 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) and a second layer containing a resin (e.g., PP) and a carbon-based filler (e.g., carbon black). In this case, the weight percent concentration of the carbon-based filler may be different between the first layer and the second layer, or the type of at least one of the resin and the carbon-based filler may be different between the first layer and the second layer.

[0058] The above describes the embodiments of the present invention by way of example. That is, the detailed description and the accompanying drawings are disclosed for the purpose of illustrative description. Therefore, some components described in the detailed description and the accompanying drawings may be non-essential components for solving the problem. Therefore, just because the non-essential components are described in the detailed description and the accompanying drawings, it should not be immediately determined that the non-essential components are essential.

[0059] Furthermore, the above-described embodiment is merely an example of the present invention in every respect. The above-described embodiment can be improved or modified in various ways within the scope of the present invention. In other words, in implementing the present invention, specific configurations can be appropriately adopted according to the embodiment. EXAMPLES

[0060] Examples of the present invention will be described below, but the present invention is not limited to the following examples.

[0061] [1. Examples and Comparative Examples] The conductive films of Examples 1-3 and Comparative Example were manufactured using a manufacturing apparatus 40 shown in Fig. 2. Specifically, the conductive films of Examples 1-3 and Comparative Example were manufactured by co-extrusion. In the conductive films of Examples 1-3 and Comparative Example, 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 formation speed during the manufacturing of the conductive films of Examples 1-3 and Comparative Example was 2.5 m / min.

[0062] In each of the conductive films of Examples 1-3 and the 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 1-3 and the comparative example, the weight percent concentration of nickel in the second conductive resin layer 200 (each of the first surface side layer 210 and the second surface side layer 220) was 70 wt%. 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 were added to the second conductive resin layer 200. In the conductive film of Example 2, Irganox B225 manufactured by BASF Japan Ltd. was added to the second conductive resin layer 200. In the conductive film of Example 3, Irganox B215 manufactured by BASF Japan Ltd. was added to the second conductive resin layer 200. In the conductive film of the comparative example, no antioxidant was added. The amount of antioxidant added to each conductive film was as shown in Table 1 below. The amount of each antioxidant added in Table 1 indicates the ratio to the weight of polypropylene contained in the second conductive resin layer 200. In addition, in Example 1, the amount of ADK STAB AO-60 added was 0.2% of the weight of PP in the second conductive resin layer 200, and the amount of ADK STAB HP-10 added was 0.2% of the weight of PP in the second conductive resin layer 200. [Table 1]

[0065] [2. Various measurements] <2-1. Measurement of volume resistivity> The volume resistivity of each of the conductive films of Examples 1 to 3 and Comparative Example was measured. Specifically, the volume resistivity of each of the conductive films was measured by a method in accordance with JIS K 7194.

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

[0067] [3. Measurement results] The measurement results for each of the conductive films of Examples 1 to 3 and the comparative example are shown in Table 2 below. [Table 2]

[0068] As shown in Table 2, the volume resistivity of each of the conductive films of Examples 1-3 was lower than the volume resistivity of the conductive film of the comparative example, and the surface resistance of each of the conductive films of Examples 1-3 was lower than the surface resistance of the conductive film of the comparative example. [Explanation of symbols]

[0069] 10, 10A conductive film, 40, 40A manufacturing apparatus, 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, 400 AT die, 401 T die body, 410, 420 casting roll, 430 winding roll, 440, 450, 460 raw material input section.

Claims

1. Resin and A conductive filler; and an antioxidant that suppresses oxidation of the resin; The conductive film, wherein the antioxidant includes at least one of a phenol-based antioxidant and a phosphite-based antioxidant.

2. The conductive film according to claim 1 , which has a volume resistivity of 100 Ω·cm or less.

3. 3. The conductive film according to claim 1, wherein the antioxidant is added in an amount of 0.1% or more and 0.5% or less based on a weight of the resin.

4. A first layer; a second layer laminated to 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 conductive film according to claim 1 , wherein the antioxidant is contained in at least one of the first layer and the second layer.

5. the first conductive filler is a carbon-based filler; The conductive film according to claim 4 , wherein the second conductive filler is a metal-based filler.

6. A step of producing a molten material by heating and melting a resin, a conductive filler, and an antioxidant that inhibits oxidation of at least the resin; and producing a conductive film by extruding the molten material; The method for producing a conductive film, wherein the antioxidant includes at least one of a phenol-based antioxidant and a phosphite-based antioxidant.

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