WO2024057827A1

WO2024057827A1 - Electroconductive film

Info

Publication number: WO2024057827A1
Application number: PCT/JP2023/029952
Authority: WO
Inventors: 宗一郎山中
Original assignee: グンゼ株式会社
Priority date: 2022-09-13
Filing date: 2023-08-21
Publication date: 2024-03-21
Also published as: JP2024040688A

Abstract

This electroconductive film comprises an electroconductive film body and a metal layer. The electroconductive film body contains a resin and an electroconductive material. The metal layer is layered on the electroconductive film body. When the electroconductive film is heated from 20°C to 80°C and then cooled from 80°C to 20°C in a test carried out using a thermomechanical analyzer (TMA), the rate of change in the machine direction (MD) dimension of the electroconductive film is −0.10% or higher. In the test, the load by which the electroconductive film is stretched is 0.0035 N, the speed of the temperature change during heating is 5.0°C/min, and the speed of the temperature change during cooling is −5.0°C/min.

Description

conductive film

The present invention relates to a conductive film.

JP 2020-97142A (Patent Document 1) discloses a conductive film. This conductive film includes a resin film and a metal layer laminated on the resin film.

JP2020-97142A

Consider a case where a predetermined thermal shock test is performed on a conductive film that includes a layer containing resin and a metal layer. For example, when a conductive film is heated from 20° C. to 80° C. and then subjected to a predetermined thermal shock test in which the conductive film is cooled from 80° C. to 20° C., the conductive film contracts. When the conductive film is further cooled (for example, to −20° C.), the resin-containing layer fixed to the metal layer further shrinks, which may cause cracks in the resin-containing layer. The above-mentioned Patent Document 1 does not disclose any means for solving such problems.

The present invention has been made to solve such problems, and the purpose is to provide a conductive film that can suppress the occurrence of cracks caused by further cooling of the conductive film after passing through a predetermined thermal shock test. The purpose is to provide sex films.

The conductive film according to the present invention includes a conductive film body and a metal layer. The conductive film body includes a resin and a conductive material. The metal layer is laminated to the conductive film body. In a test using TMA (Thermomechanical Analyzer), when the conductive film was heated from 20°C to 80°C and then cooled from 80°C to 20°C, the MD (Machine Direction) of the conductive film was determined. The rate of change in dimensions is -0.10% or more. In the above test, the load pulling the conductive film was 0.0035N, the rate of temperature change during heating was 5.0°C/min, and the rate of temperature change during cooling was -5.0°C/min. be.

In this conductive film, in a test using TMA, when the conductive film was heated from 20°C to 80°C and then cooled from 80°C to 20°C, the dimensional change rate in MD was is -0.10% or more. That is, this conductive film has a relatively small shrinkage rate when subjected to a predetermined thermal shock test. Therefore, according to this conductive film, the shrinkage rate after passing through the prescribed thermal shock test is relatively small, so even if the conductive film is further cooled after passing through the prescribed thermal shock test, the occurrence of cracks is suppressed. can do.

In the above conductive film, the relaxation temperature of residual stress in the conductive film body may be higher than 80°C.

In this conductive film, the relaxation temperature of residual stress in the conductive film body is higher than 80°C, so the conductive film is heated from 20°C to 80°C, and then the conductive film is heated from 80°C to 20°C. Even after undergoing a prescribed thermal shock test during cooling, no large shrinkage occurs in the conductive film body. Therefore, according to this conductive film, the shrinkage rate after passing through the prescribed thermal shock test is relatively small, so even if the conductive film is further cooled after passing through the prescribed thermal shock test, the occurrence of cracks is suppressed. can do.

In addition, in the above conductive film, the conductive film body includes a first conductive resin layer containing a first conductive filler and a second conductive resin layer containing a second conductive filler, the first conductive filler being conductive carbon, and the second conductive filler may include at least one metal selected from the group including platinum, gold, silver, copper, SUS (Stainless Used Steel), nickel, and titanium.

Furthermore, in the conductive film, the product of the breaking strength in MD and the breaking strength in TD (Traverse Direction) may be 710 or more.

According to this conductive film, the product of the breaking strength in MD and the breaking strength in TD is relatively large, so even if the conductive film is further cooled after a prescribed thermal shock test, the occurrence of cracks is suppressed. be able to.

According to the present invention, it is possible to provide a conductive film that can suppress the occurrence of cracks due to further cooling of the conductive film after passing through a predetermined thermal shock test.

FIG. 3 is a diagram showing a cross section of a conductive film. FIG. 3 is a diagram for explaining an image of dimensional changes caused by passing through a predetermined thermal shock test. FIG. 1 is a diagram schematically showing the configuration of a manufacturing device.

Hereinafter, an embodiment (hereinafter also referred to as "this embodiment") according to one aspect of the present invention will be described in detail using the drawings. In addition, the same reference numerals are attached to the same or corresponding parts in the drawings, and the description thereof will not be repeated. Further, each drawing is schematically drawn with objects omitted or exaggerated as appropriate for ease of understanding.

[1. Structure of conductive film]
FIG. 1 is a diagram showing a cross section of a conductive film 10 according to this embodiment. The conductive film 10 is used, for example, as a charging film or an antistatic film for copying machines, printers, etc., and various functional films for other electric/electronic devices and parts. As shown in FIG. 1, the conductive film 10 includes a conductive film body 15 and a metal coating layer 300. The conductive film body 15 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, 0.5 times or more and 5 times or less the thickness T2 of the second conductive resin layer 200. Each layer will be explained below.

<1-1. First conductive resin layer>
The first conductive resin layer 100 contains polyolefin and conductive filler. That is, the first conductive resin layer 100 is formed by mixing polyolefin and conductive filler.

Examples of polyolefins include polypropylene (PP) and polyethylene (PE). Further, a polymer having an α-olefin having 4 to 30 carbon atoms (1-butene, isobutene, 1-hexene, 1-decene, or 1-dodecene, etc.) as an essential constituent monomer may also be used as the polyolefin. . These polyolefins may be used alone or in a mixture of two or more.

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

An example of the conductive filler included in the first conductive resin layer 100 is conductive carbon. Examples of the conductive carbon include graphite, carbon black (acetylene black, Ketjen black, furnace black, channel black, thermal lamp black, etc.), carbon nanotubes, and mixtures thereof. Among the conductive carbons, carbon black is preferred, and acetylene black, furnace black, or a mixture thereof is more preferred.

<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 layer 210 and a second surface layer 220. Note that 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 .

The first surface layer 210 and the second surface layer 220 each contain a polyolefin and a conductive filler. That is, each of the first surface layer 210 and the second surface layer 220 is formed by mixing polyolefin and a conductive filler. As the polyolefin, for example, those exemplified in the description of the first conductive resin layer 100 can be used.

Examples of the conductive filler included in the second conductive resin layer 200 include platinum, gold, silver, copper, nickel, titanium, and mixtures thereof. That is, the conductive filler contained in the second conductive resin layer 200 contains at least one metal element selected from the group containing platinum, gold, silver, copper, nickel, and titanium. Note that among these, nickel particles are more preferable as the conductive filler. For example, in the second conductive resin layer 200, the second surface layer 220 contains more conductive filler than the first surface layer 210.

<1-3. Metal coating layer>
The metal coating layer 300 is formed on the second surface 230 of the second conductive resin layer 200. The metal coating layer 300 may be made of, for example, at least one of nickel, copper, silver, and aluminum. Further, the metal coating layer 300 may be composed of an oxide or an alloy thereof. The metal coating layer 300 is formed, for example, by a known technique such as a vapor deposition method, a sputtering method, a plating method, or a coating method. The thickness of the metal coating layer 300 is not particularly limited, but is preferably 10 to 100 nm.

[2. Various parameters]
<2-1. Dimensional change after thermal shock test>
The conductive film 10 has a characteristic that the dimensional change rate in MD (Machine Direction) after passing through a predetermined thermal shock test is "-(minus) 0.10%" or more. The prescribed thermal shock test is a test using a TMA (Thermomechanical Analyzer). In this test, the conductive film 10 is heated from 20°C to 80°C, and then the conductive film 10 is cooled from 80°C to 20°C. The conductive film 10 has a characteristic that the MD dimensional change rate after heating and cooling is -0.10% or more.

FIG. 2 is a diagram for explaining an image of dimensional changes caused by passing through a predetermined thermal shock test. Referring to FIG. 2, the horizontal axis represents temperature, and the vertical axis represents the rate of change in dimension in MD. As mentioned above, the conductive film 10 is heated from 20°C to 80°C. By being heated, the dimensions of the conductive film 10 gradually increase. Thereafter, the conductive film 10 is cooled from 80°C to 20°C. As the conductive film 10 is cooled, the dimensions of the conductive film 10 gradually become smaller. In this example, after heating and cooling, the dimension in MD of the conductive film 10 becomes smaller than before heating. The conductive film 10 has the characteristic that this dimensional change rate is -0.10% or more.

As described above, the conductive film 10 has a relatively small shrinkage rate when subjected to a predetermined thermal shock test. Therefore, since the conductive film 10 has a relatively small shrinkage rate after passing through a predetermined thermal shock test, even if the conductive film 10 is further cooled after passing through a predetermined thermal shock test (for example, - Even if the material is cooled to 20° C., the occurrence of cracks can be suppressed.

<2-2. Residual stress relaxation temperature>
The conductive film 10 has a characteristic that the relaxation temperature of residual stress in the conductive film body 15 is higher than 80°C. Although details will be described later, in the manufacturing process of the conductive film main body 15, a device is adopted in which the molten material begins to solidify at a relatively high temperature. As the molten material begins to solidify at a relatively high temperature, the relaxation temperature of residual stress in the conductive film body 15 increases.

In the conductive film body 15, the residual stress relaxation temperature is higher than 80°C, so the conductive film 10 is heated from 20°C to 80°C, and then the conductive film 10 is cooled from 80°C to 20°C. Even after passing through a predetermined thermal shock test, no large shrinkage occurs in the conductive film body 15. Therefore, since the conductive film 10 has a relatively small shrinkage rate when subjected to a predetermined thermal shock test, cracks do not occur even if the conductive film 10 is further cooled after undergoing a predetermined thermal shock test. Can be suppressed.

<2-3. Breaking strength and breaking elongation>
The conductive film 10 has a characteristic that the product of the breaking strength in MD and the breaking strength in TD (breaking strength product) is 710 or more. Further, the conductive film 10 has a characteristic that the product of the elongation at break in MD and the elongation at break in TD (product of elongation at break) is 7 or more.

[3. Manufacturing method of conductive film]
FIG. 3 is a diagram schematically showing the configuration of the manufacturing apparatus 40. As shown in FIG. The conductive film main body 15 is manufactured by the manufacturing apparatus 40 . As shown in FIG. 3, the manufacturing apparatus 40 includes a T-die 400, cast rolls 410, 420, and a take-up roll 430.

The T-die 400 includes a T-die main body 401 and raw

material input parts

440, 450, and 460. Raw materials for forming the second surface side layer 220 are charged into the raw material input section 440 . For example, polypropylene and nickel are charged into the raw material input section 440. Raw materials for forming the first surface side layer 210 are charged into the raw material input section 450 . For example, polypropylene and nickel are charged into the raw material input section 450. The weight percent concentration of nickel in the raw material input to the raw material input section 450 is lower than the weight percent concentration of nickel in the raw material input to the raw material input section 440. Raw materials for forming the first conductive resin layer 100 are charged into the raw material input section 460 . For example, polypropylene and carbon black are charged into the raw material input section 460.

The T-die main body 401 co-extrudes the raw materials input through the raw

material input parts

440, 450, and 460, thereby melting the raw materials input into each raw material input part and melting them together to form one integral piece. It is configured to produce a molten film (molten material). Cast rolls 410, 420 are configured to cool the extruded molten material and send it downstream. The winding roll 430 is configured to pull and wind up the molten material cooled by the cast rolls 410, 420 at a predetermined speed. A rolled body of the conductive film body 15 is manufactured through the manufacturing process in the manufacturing apparatus 40. The conductive film 10 is manufactured by forming the metal coating layer 300 on the conductive film body 15 manufactured by the manufacturing apparatus 40 by a known technique such as a vapor deposition method, a sputtering method, a plating method, or a coating method.

In the manufacturing apparatus 40, for example, the temperature of the cast roll 410 is 40°C or higher and 120°C or lower, preferably 80°C or higher and 120°C or lower. Moreover, the temperature of the cast roll 420 is 80°C or more and 120°C or less, preferably 90°C or more and 120°C or less.

In the manufacturing apparatus 40, the temperature of the cast roll 420 is high to some extent. As a result, according to the manufacturing apparatus 40, the molten material discharged from the T-die 400 begins to harden at a relatively high temperature, so that it is possible to manufacture the conductive film body 15 with a relatively high residual stress relaxation temperature. can. For example, the residual stress relaxation temperature of the conductive film body 15 manufactured by the manufacturing apparatus 40 is higher than 80°C.

In the conductive film body 15 manufactured by the manufacturing apparatus 40, the relaxation temperature of residual stress is higher than 80° C., so that no large shrinkage occurs in the conductive film body 15 even after passing through the above-described prescribed thermal shock test. . Therefore, according to the conductive film 10, the shrinkage rate after passing through a predetermined thermal shock test is relatively small, so even if the conductive film 10 is further cooled after passing through a predetermined thermal shock test (for example, -20 Crack generation can be suppressed.

[4. Features]
As described above, in the conductive film 10 according to the present embodiment, in a test using TMA, the conductive film 10 is heated from 20°C to 80°C, and then the conductive film 10 is heated from 80°C to 20°C. When cooled to a temperature of -0.10% or more, the dimensional change rate in MD is -0.10% or more. That is, the conductive film 10 has a relatively small shrinkage rate when subjected to a predetermined thermal shock test. Therefore, since the conductive film 10 has a relatively small shrinkage rate when subjected to a predetermined thermal shock test, cracks do not occur even if the conductive film 10 is further cooled after the predetermined thermal shock test. Can be suppressed.

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

<5-1>
In the conductive film 10 according to the embodiment described above, the conductive filler contained in the first conductive resin layer 100 is at least one metal selected from the group containing platinum, gold, silver, copper, nickel, and titanium. It may further contain elements.

<5-2>
The conductive film 10 according to the above embodiment is a film having a multi-layer structure. However, the conductive film 10 does not necessarily have to have a multi-layer structure, and may have a single layer structure. The conductive film having a single layer structure may contain, for example, a polyolefin and a conductive filler. As the polyolefin, for example, one exemplified in the description of the first conductive resin layer 100 may be used. As the conductive filler, at least one metal element selected from the group including platinum, gold, silver, copper, nickel, and titanium may be included.

<5-3>
In the conductive film 10 according to the embodiment described above, the conductive film body 15 included a first conductive resin layer 100 and a second conductive resin layer 200. However, the conductive film body 15 does not necessarily need to include both the first conductive resin layer 100 and the second conductive resin layer 200. For example, the conductive film body 15 may include the second conductive resin layer 200 but may not include the first conductive resin layer 100.

The embodiments of the present invention have been exemplarily described above. That is, the detailed description and accompanying drawings have been disclosed for purposes of illustration. Therefore, some of the components described in the detailed description and the attached drawings may not be essential for solving the problem. Therefore, just because non-essential components are described in the detailed description and accompanying drawings, such non-essential components should not be immediately identified as essential.

Furthermore, the above embodiments are merely illustrative of the present invention in all respects. Various improvements and changes can be made to the above embodiments within the scope of the present invention. That is, in implementing the present invention, specific configurations can be adopted as appropriate depending on the embodiment.

Examples of the present invention will be described below. Note that the present invention is not limited to the following examples.

[1. Example]
Each conductive film of Examples 1 and 2 was manufactured using the manufacturing apparatus 40 shown in FIG. 3. Specifically, the conductive films of Examples 1 and 2 were manufactured by manufacturing a conductive film body by coextrusion and depositing copper on the conductive film body. In each of the conductive films of Examples 1 and 2, 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.

In each of the conductive films of Examples 1 and 2, 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.

In each of the conductive films of Examples 1 and 2, the weight percent concentration of nickel in the second surface layer 220 of the second conductive resin layer 200 was 75 wt%, and the weight percent concentration of nickel in the second surface side layer 220 of the second conductive resin layer 200 was 75 wt%. The weight percent concentration of nickel in the side layer 210 was 70 wt%. The weight percent concentration of carbon black in the first conductive resin layer 100 was 30 wt%.

In the manufacturing process of the conductive film of Example 1, the temperature of the cast roll 410 was 90°C, and the temperature of the cast roll 420 was 100°C. In the manufacturing process of the conductive film of Example 2, the temperature of the cast roll 410 was 110°C, and the temperature of the cast roll 420 was 70°C.

The conductive film of Example 3 was manufactured using a single-layer film manufacturing apparatus. This manufacturing apparatus was the same as the manufacturing apparatus 40 shown in FIG. 3 in which the T-die 400 was replaced with another T-die. This T-die was configured to discharge a single layer of molten material.

A conductive film body was manufactured by heating and melting polypropylene and nickel and extrusion molding, and the conductive film of Example 3 was manufactured by vapor depositing copper on the conductive film body. The weight percent concentration of nickel in the conductive film of Example 3 was 50 wt%. The thickness of the conductive film of Example 3 was 50 μm. In the manufacturing process of the conductive film of Example 3, the temperature of cast roll 410 was 100°C, and the temperature of cast roll 420 was 90°C.

[2. Comparative example]
A conductive film of a comparative example was manufactured using the manufacturing apparatus 40 shown in FIG. 3. Specifically, a conductive film body was manufactured by coextrusion, and a conductive film of a comparative example was manufactured by vapor depositing copper on the conductive film body. In the conductive film of the 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 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.

In the conductive film of the comparative example, the weight percentage concentration of nickel in the second surface side layer 220 of the second conductive resin layer 200 is 75 wt%, and the weight percent concentration of nickel in the first surface side layer 210 of the second conductive resin layer 200 is 75 wt%. The weight percent concentration of nickel in was 70 wt%. The weight percent concentration of carbon black in the first conductive resin layer 100 was 30 wt%.

In the manufacturing process of the conductive film of the comparative example, the temperature of the cast roll 410 was 90°C, and the temperature of the cast roll 420 was 70°C.

[3. Various tests and measurements]
<3-1. Measurement of dimensional change rate through thermal shock test>
The dimensional change rate in MD of each conductive film was measured using TMA Q400 manufactured by TA Instruments Japan. Regarding the sample size of each conductive film, the width was 4.9 mm, and the distance between chucks was 16 mm. In this test, the temperature of each conductive film was heated from 20°C to 80°C, and then cooled from 80°C to 20°C. Note that no hold was performed at each temperature. In this test, the load pulling the conductive film was 0.0035N, the rate of temperature change during heating was 5.0°C/min, and the rate of temperature change during cooling was -5.0°C/min. Met.

<3-2. Measurement of residual stress relaxation temperature>
The residual stress relaxation temperature of each conductive film was measured using TMA Q400 manufactured by TA Instruments Japan. Regarding the sample size of each conductive film, the width was 4.9 mm, and the distance between chucks was 16 mm. In this test, the temperature of the conductive film was raised from 20° C. to 130° C., and the temperature at which the thermal expansion of the conductive film turned into thermal contraction during this constant temperature increase process was defined as the residual stress relaxation temperature. In this test, the load pulling the conductive film was 0.0035 N, and the rate of temperature change during heating was 10° C./min.

<3-3. Measurement of breaking strength>
The tensile strength at break in each of MD and TD was measured by a method based on JIS-K-6732. The size of the sample used to measure the tensile strength at break (MPa) was 10 mm in width and 110 mm or more in length (the length of the gauge line in the sample was 40 mm±0-2). The thickness of the sample was measured at five equally spaced points in the length direction, and the average thickness was calculated based on the measured thickness at the five points. Specific measurements were performed using an autograph (Shimadzu precision universal testing machine Autograph AG-X 500N). The tensile speed at that time was 200 mm/min, the chart speed was 200 mm/min, and the grip interval was 40 mm. The strength of the sample at break was defined as the tensile strength at break.

<3-4. Measurement of elongation at break>
The tensile elongation at break in each of MD and TD was measured by a method based on JIS-K-6732. The size of the sample used to measure the tensile elongation at break (%) was 10 mm in width and 110 mm or more in length (the length of the gauge line in the sample was 40 mm±0-2). The thickness of the sample was measured at five equally spaced points in the length direction, and the average thickness was calculated based on the measured thickness at the five points. Specific measurements were performed using an autograph (Shimadzu precision universal testing machine Autograph AG-X 500N). The tensile speed at that time was 200 mm/min, the chart speed was 200 mm/min, and the grip interval was 40 mm. The elongation of the sample at break was defined as the tensile elongation at break.
<3-5. Cracking test>
The conductive film was cut into a size of 300 x 300 mm, and the four sides of the cut sample were fixed. Place the sample with the four sides fixed in a constant temperature and humidity chamber (LHU-113) manufactured by ESPEC Corporation, heat the temperature inside the constant temperature and humidity chamber from 20℃ to 80℃, and then heat it in the high temperature and humidity chamber. The temperature was cooled from 80°C to -20°C. Note that the rate of temperature change was 5.0° C./min. Cracks were observed in the sample that underwent this process.

[4. Test and measurement results]
The test and measurement results are shown in Table 1 below.

The breaking strength of each of MD and TD was measured as a value in MPa, and the product of the breaking strength value in MD and the breaking strength value in TD was defined as the breaking strength product. Further, the elongation at break in each of MD and TD was measured as a percentage value, and the product of the numerical value of the elongation at break in MD and the numerical value of elongation at break in TD was defined as the elongation at break product. Note that each of the product of strength at break and the product of elongation at break was an index value without a unit. Further, the residual stress relaxation temperature of Example 1 was 96°C, the residual stress relaxation temperature of Example 2 was 83°C, and the residual stress relaxation temperature of Example 3 was 86°C. The residual stress relaxation temperature of the comparative example was 65°C. As shown in Table 1, no cracks occurred in each of Examples 1-3, and cracks occurred in Comparative Examples.

Reference Signs List 10 conductive film, 15 conductive film main body, 40 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, 300 metal coating layer, 400 T die, 401 T die body, 410, 420 cast roll, 430 winding roll, 440, 450, 460 raw material input section.

Claims

A conductive film,
a conductive film body containing a resin and a conductive material;
a metal layer laminated on the conductive film body,
In a test using a TMA (Thermomechanical Analyzer), when the conductive film was heated from 20°C to 80°C and then cooled from 80°C to 20°C, the MD of the conductive film ( The rate of change in dimensions in machine direction) is -0.10% or more,
In the test, the load pulling the conductive film was 0.0035N, the rate of temperature change during heating was 5.0°C/min, and the rate of temperature change during cooling was -5.0°C/min. conductive film.
The conductive film according to claim 1, wherein the residual stress relaxation temperature in the conductive film body is higher than 80°C.
The conductive film according to claim 1 or 2, wherein the product of the breaking strength in MD and the breaking strength in TD (Traverse Direction) is 710 or more.