Titanium ring and copper foil manufacturing drum

Abstract

To provide a titanium ring and a copper foil manufacturing drum that can suppress the occurrence of macroscopic patterns when used in a copper foil manufacturing drum. [Solution] A titanium ring according to one aspect of the present invention has a predetermined chemical composition, has no seams, and the difference between the maximum and minimum values ​​of the average grain size of the grain size distribution obtained at five measurement positions, which are 1 mm deep in the radial direction from the outer surface of the titanium ring and equally spaced in the circumferential direction, is 10 μm or less, the difference between the maximum and minimum values ​​of the standard deviation of the log-normal distribution function of the grain size distribution is 0.1 or less, and in a graph showing the area ratio of crystal grains for each angle between the radial direction and the c-axis of the hexagonal close-packed structure at each of the five measurement positions, the difference between the maximum and minimum values ​​of the angle where the area ratio is maximized is within 10 degrees, and the maximum value of the square of the area ratio difference for each angle is 0.05 or less.

Description

[Technical Field]

[0001] This invention relates to titanium rings and copper foil manufacturing drums. [Background technology]

[0002] Copper foil is often used as a raw material for the wiring in circuit boards such as multilayer circuit boards and flexible circuit boards, as well as for the conductive parts of electronic components such as current collectors in lithium-ion batteries.

[0003] Copper foil used for such applications is manufactured by a copper foil manufacturing apparatus equipped with a copper foil manufacturing drum. Figure 6 is a schematic diagram of the copper foil manufacturing apparatus. The copper foil manufacturing apparatus 1 includes, for example, an electrolytic cell 10 in which a copper sulfate solution is stored, a copper foil manufacturing drum 2 provided in the electrolytic cell 10 so as to be partially immersed in the copper sulfate solution, and an electrode plate 30 provided in the electrolytic cell 10 so as to be immersed in the copper sulfate solution and facing the outer surface of the copper foil manufacturing drum 2 at a predetermined distance. The size of the copper foil manufacturing drum 2 is generally, for example, 1 m or more in width and several m in diameter. The electrode plate 30 is made of an insoluble metal such as platinum or iridium-coated titanium. With the electrode plate 30 as the anode and the copper foil manufacturing drum 2 as the cathode, a voltage is applied to them while rotating the copper foil manufacturing drum 2, causing copper foil A to be electrodeposited onto the outer surface of the copper foil manufacturing drum 2. The copper foil A, once it reaches the predetermined thickness, is peeled from the copper foil manufacturing drum 2 by the winding unit 40 and wound onto the winding roll 60 while being guided by the guide roll 50.

[0004] Titanium is commonly used for the surface (outer surface) of copper foil manufacturing drums due to its superior specific strength, corrosion resistance, and ease of copper foil release. For these reasons, titanium materials suitable for this purpose have been developed.

[0005] In particular, to meet the demand for high-precision and uniform thickness copper foil manufacturing, titanium plates superior to copper foil manufacturing have been developed, such as the technology described in Patent Document 1, which have a uniform and fine structure, and whose texture is adjusted to suppress the occurrence of macro-patterns that occur on the surface of the copper foil manufacturing drum after polishing or during copper foil manufacturing. Macro-patterns are the irregularities and patterns caused by the material structure that occur on the surface of the drum after polishing or during copper foil manufacturing.

[0006] When manufacturing copper foil drums, titanium material is provided on the outer circumference of the inner drum. When plate-shaped titanium material (titanium plates) is used for this titanium material, the ends of the titanium plates are butted together and welded to form a ring. As a result, structural changes occur in the heat-affected zone at and near the weld, which can easily lead to the formation of macroscopic patterns.

[0007] To suppress the occurrence of macroscopic patterns in welded areas and heat-affected zones, it is conceivable to use titanium rings manufactured by ring rolling on the surface of copper foil manufacturing drums. For example, Patent Document 2 describes a method for manufacturing titanium rings for copper foil manufacturing drums, in which a titanium material heated to a temperature not exceeding 700°C is annularly rolled under conditions of a processing rate of 30% or more per heating cycle and an outer diameter growth rate of 8 mm / second or less. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] International Publication No. 2020 / 213715 [Patent Document 2] Japanese Patent Application Publication No. 7-223034 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] However, even titanium rings manufactured by conventional ring rolling, such as the technology described in Patent Document 2, are not sufficient to suppress the occurrence of macroscopic patterns, and there is room for further quality improvement.

[0010] This invention has been made in view of the above circumstances, and aims to provide a titanium ring and a copper foil manufacturing drum that can suppress the occurrence of macro patterns when used in a copper foil manufacturing drum. [Means for solving the problem]

[0011] The inventors of this invention discovered that by appropriately controlling the crystal grain size distribution and crystal orientation distribution, macroscopic patterns are less likely to occur in titanium rings, leading to the present invention.

[0012] Based on the above findings, the gist of the present invention is as follows: [1] A titanium ring according to one aspect of the present invention has a chemical composition by mass%, containing Fe: 0.010~0.045%, O: less than 0.010~0.200%, Cu: 0~1.00%, Al: 0~2.00%, Sn: 0~2.00%, Zr: 0~2.00%, C: less than 0.080%, N: 0~0.050%, and H: 0~0.0150%, with the remainder being Ti and impurities, and has no seams, and extends 1 mm in the radial direction from the outer circumferential surface of the titanium ring, and the titanium ring The difference between the maximum and minimum average grain size of the grain size distribution obtained at five equally spaced measurement positions in the circumferential direction is 10 μm or less, and the difference between the maximum and minimum standard deviations of the log-normal distribution function of the grain size distribution is 0.1 or less, and in a graph showing the area ratio of grains for each angle between the radial direction and the c-axis of the hexagonal close-packed structure at each of the five measurement positions, the difference between the maximum and minimum values ​​of the angle at which the area ratio is maximized is within 10 degrees, and the maximum value of the square of the area ratio difference for each angle is 0.05 or less.

[0013] [2] Another embodiment of the present invention provides a copper foil manufacturing drum comprising a cylindrical inner drum and the titanium ring described in [1] above attached to the outer surface of the inner drum. [Effects of the Invention]

[0014] According to the present invention, generation of macro patterns can be suppressed when used for a copper foil manufacturing drum.

Brief Description of the Drawings

[0015] [Figure 1] It is an example of a graph showing crystal grain sizes and their ratios (frequencies) at two different measurement positions in the circumferential direction at a depth of 1 mm in the radial direction from the outer peripheral surface of a conventional titanium ring. [Figure 2] It is an example of a graph showing crystal grain sizes and their ratios (frequencies) at two different measurement positions in the circumferential direction at a depth of 1 mm in the radial direction from the outer peripheral surface of a titanium ring according to an embodiment of the present invention. [Figure 3] It is an example of a graph showing the area ratio of crystal grains for each angle formed by the radial direction and the c-axis of hcp at two different measurement positions in the circumferential direction at a depth of 1 mm in the radial direction from the outer peripheral surface of a conventional titanium ring. [Figure 4] It is an example of a graph showing the area ratio of crystal grain sizes for each angle formed by the radial direction and the c-axis of hcp at two different measurement positions in the circumferential direction at a depth of 1 mm in the radial direction from the outer peripheral surface of a titanium ring according to an embodiment of the present invention. [Figure 5] It is a schematic diagram of a copper foil manufacturing drum according to an embodiment of the present invention. [Figure 6] It is a schematic diagram showing a schematic configuration of a copper foil manufacturing apparatus.

Mode for Carrying Out the Invention

[0016] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[0017] <Titanium Ring> A titanium ring according to one embodiment of the present invention has a chemical composition consisting of, by mass%, Fe: 0.010~0.045%, O: less than 0.01~0.200%, Cu: 0~1.0%, Al: 0~2.0%, Sn: 0~2.0%, Zr: 0~2.0%, C: less than 0.08%, N: 0.05% or less, and H: 0~0.0150%, with the remainder being Ti and impurities. Furthermore, the titanium ring according to this embodiment has no seams, and the difference between the maximum and minimum values ​​of the average grain size distribution obtained at five measurement positions, which are 1 mm deep in the radial direction of the titanium ring from the outer circumferential surface of the titanium ring and equally spaced in the circumferential direction of the titanium ring, is 10 μm or less, and the difference between the maximum and minimum values ​​of the standard deviation of the log-normal distribution function of the grain size distribution is 0.1 or less. Furthermore, in the titanium ring according to this embodiment, in a graph showing the area ratio of crystal grains for each angle between the radial direction and the c-axis of the hexagonal close-packed structure at each of the five measurement positions, the difference between the maximum and minimum values ​​of the angle at which the area ratio is maximized is within 10 degrees, and the maximum value of the square of the area ratio difference for each angle is 0.05 or less.

[0018] (chemical composition) The titanium ring according to this embodiment is made of industrial-grade pure titanium or a titanium alloy having a metallic structure with the α phase as the main phase. Copper foil is manufactured in a corrosive environment, as described above. Therefore, depending on the titanium ring, the surface may become rough due to corrosion, and macroscopic patterns may occur. Since the β phase is more susceptible to corrosion than the α phase, it is desirable to have a smaller proportion of the β phase. Also, in order to uniformly form Cu crystal nuclei during copper foil manufacturing, it is important to make the grain size of the titanium ring relatively large. If the proportion of the β phase is large, it becomes difficult to enlarge the grain size due to the pinning effect. Therefore, it is desirable to have a small proportion of the β phase and a large proportion of the α phase. The β phase may be, for example, 1.0 volume% or less, 0.5 volume% or less, or 0 volume%. In addition, if the titanium material contains Cu, Ti2Cu may be formed. The Ti2Cu may be, for example, 1.0 volume% or less, 0.5 volume% or less, or 0 volume%. The titanium ring according to this embodiment preferably has a composition of 99.5% by volume or less, 99.0% by volume or less, 98.5% by volume or less, or 98.0% by volume or less, and more preferably is an α-phase single phase. To ensure that the α phase is the dominant phase, the composition and range of the titanium ring shall be as follows. Unless otherwise specified below, the "%" notation for chemical composition shall represent "mass%".

[0019] Fe: 0.010~0.045% Fe (iron) is a β-stabilizing element and is included in industrial pure titanium for solid solution strengthening. Since solid solution strengthening improves the polishability of the titanium ring, the Fe content is set to 0.010% or more. Preferably, the Fe content is 0.012% or more, or 0.015% or more. On the other hand, if the Fe content is too high, the β phase will precipitate excessively, suppressing grain growth. Therefore, in this embodiment, the Fe content is 0.045% or less. Preferably, the Fe content is 0.043% or less, or 0.040% or less.

[0020] O: Less than 0.010-0.200% Oxygen (O) is an α-stabilizing element that improves the strength of the α-phase, thereby improving the strength of the titanium ring. When the strength of the titanium ring is improved to a certain extent, the polishability improves. Therefore, the O content should be 0.010% or more. Preferably, the O content is 0.015% or more. On the other hand, if the O content is too high, it becomes too hard, making uniform polishing difficult. Therefore, the O content should be less than 0.200%. Preferably, the O content is 0.120% or less, or 0.100% or less.

[0021] Cu: 0~1.00% Like Fe, copper (Cu) is a β-stabilizing element. Furthermore, Cu has a relatively large solid solubility limit in the α phase compared to other β-stabilizing elements, so even if a large amount of Cu is present, the β phase is less likely to precipitate compared to Fe. Also, while Cu hardens the titanium material, increasing the load when processing the titanium material into a titanium ring, it makes it easier to polish uniformly. However, if the Cu content exceeds 1.00%, the Cu will not fully dissolve, and Ti2Cu or the β phase will precipitate, suppressing grain growth. Therefore, the Cu content should be 1.00% or less. On the other hand, the Cu content is preferably 0.80% or less. Cu may not be present, and the Cu content may be 0%. The Cu content is preferably 0.20% or more.

[0022] Al: 0-2.00% Aluminum (Al) is an α-stabilizing element. Furthermore, Al has high solid solution strengthening ability and can harden the α-phase. On the other hand, excessive Al content suppresses grain growth. Therefore, the Al content is preferably 2.00% or less, 1.50% or less, or 1.20% or less. Alternatively, Al may be omitted, and the Al content may be 0%. Also, to obtain solid solution strengthening ability, the Al content is preferably 0.20% or more, or 0.50% or more.

[0023] Sn: 0~2.00% Although tin (Sn) is a neutral element, it can harden the α phase through solid solution strengthening, similar to aluminum (Al). Therefore, the Sn content is preferably 2.00% or less, 1.50% or less, or 1.20% or less. On the other hand, Sn may not be present, and the Sn content may be 0%. Furthermore, in order to obtain solid solution strengthening ability, the Sn content is preferably 0.20% or more, or 0.50% or more.

[0024] Zr: 0~2.00% Zr (zirconium), like Sn, is a neutral element, but it can harden the α phase through solid solution strengthening. Therefore, the Zr content is preferably 2.00% or less, 1.50% or less, or 1.20% or less. On the other hand, Zr may not be present, and the Zr content may be 0%. Furthermore, in order to obtain solid solution strengthening ability, the Zr content is preferably 0.20% or more, or 0.50% or more.

[0025] C: Less than 0-0.080% Carbon (C) has similar effects to oxygen (O), but the strength and other properties are primarily controlled by adjusting the O content. Furthermore, C, along with Ti, can form carbides, potentially embrittle the titanium ring. Therefore, a low C content is preferable, ideally less than 0.080%. A C content of 0.050% or less is also acceptable. C may be absent, and the C content may be 0%. However, C is an impurity introduced from the raw materials such as sponge titanium, scrap, or alloying element raw materials, and the actual C content is 0.0001% or more, preferably 0.005% or more.

[0026] N: 0~0.050% Nitrogen (N) has a similar effect to oxygen (O), but the strength and other properties are primarily controlled by adjusting the O content. Furthermore, N, like O, exhibits significant solid solution strengthening, and if the O content is too high, the titanium ring becomes excessively hard. Therefore, a low N content is preferable, preferably 0.050% or less, or 0.030% or less. N may not be present at all, and the N content may be 0%. However, N is an impurity introduced from the raw materials such as sponge titanium, scrap, or alloying element raw materials, and the actual N content is 0.0001% or more, preferably 0.005% or more.

[0027] H: 0~0.0150% Hydrogen (H) is an impurity, and if the H content is too high, it forms hydrides, causing the titanium ring to become brittle. In this embodiment, since brittleness is suppressed when the H content is 0.0150% or less, the H content is preferably 0.0150% or less. The H content is more preferably 0.0100% or less. H may not be present, and the H content may be 0%. However, since H is absorbed during the manufacturing process of the titanium ring, the actual H content is 0.0010% or more.

[0028] The titanium ring according to this embodiment may contain all elements other than those mentioned above. The content of each element other than those mentioned above is, for example, 0.2% or less, and the total content is 1.0% or less. Preferably, the content of each element other than those mentioned above is 0.5% or less.

[0029] The remainder of the chemical composition of the titanium ring according to this embodiment consists of Ti and impurities. Specific examples of impurities, in addition to the elements mentioned above, include Cl, Na, Mg, Si, Ca introduced during the refining process, and Mo, Nb, Ta, V, Cr, Mn, Co, Ni, Cu, etc., introduced from scrap. The content of each impurity element is, for example, 0.2% or less, and the total content is, for example, 1.0% or less. The total content of impurities is preferably 0.5% or less.

[0030] The content of each of the above elements is quantified by ICP emission spectroscopy. However, for O and N, an oxygen-nitrogen simultaneous analyzer is used, and the results are measured by inert gas melting, thermal conductivity, and infrared absorption spectroscopy. For C, a carbon-sulfur simultaneous analyzer is used, and the results are measured by infrared absorption spectroscopy. For H, the results are measured by inert gas melting and infrared absorption spectroscopy.

[0031] (Metal structure) Next, the microstructure of the titanium ring according to this embodiment will be described. The titanium ring of this embodiment is a seamless titanium ring. A seam is a locally occurring area of ​​microstructure where the metal structure differs from that of the base material, such as the weld and heat-affected zone in a titanium ring manufactured by butt welding the end faces of titanium plates. In conventional titanium rings, if the microstructure of base material, such as the weld and heat-affected zone, can be observed. However, if the outer surface of the titanium ring is dirty or oxidized, the outer surface should be polished with #1000 to #1500 emery paper, or polished to a mirror finish, and then etched with the above aqueous solution.

[0032] The titanium ring according to this embodiment constitutes the outer layer (outer skin) of a copper foil manufacturing drum (electroplated drum). If the crystal grain size near the outer surface of the titanium ring is not uniform, the surface properties will not be uniform during polishing after drum manufacturing or before copper foil manufacturing, resulting in macroscopic patterns on the outer surface of the titanium ring, which may be transferred to the copper foil. Therefore, it is important that the crystal grain size of the titanium ring is uniform.

[0033] In this embodiment, the titanium ring has a grain size distribution obtained at five measurement positions, each equally spaced in the circumferential direction of the titanium ring and with a depth of 1 mm from the outer surface of the titanium ring. The difference between the maximum and minimum values ​​of the grain size distribution (average grain size difference) is within 10 μm, and the difference between the maximum and minimum values ​​of the standard deviation of the log-normal distribution function of the grain size distribution (σ difference) is 0.1 or less.

[0034] Figure 1 is an example of a graph showing the grain size and its ratio (frequency) at two different measurement points in the circumferential direction at a depth of 1 mm radially from the outer surface of a conventional titanium ring. Figure 2 is an example of a graph showing the grain size and its ratio (frequency) at two different measurement points in the circumferential direction at a depth of 1 mm radially from the outer surface of a titanium ring according to an embodiment of the present invention.

[0035] In conventional titanium rings, for example, as shown in Figure 1, the grain size distribution can vary significantly depending on the measurement position in the circumferential direction. More specifically, there can be variations in the grain size and standard deviation at which the frequency is highest for each measurement position. If there is a large variation in the average grain size and standard deviation of grain size in the circumferential direction, it can lead to differences in the degree of corrosion of the titanium ring surface during copper foil manufacturing, making it easier for macroscopic patterns to form. However, if there is a small variation in the average grain size and standard deviation of grain size, the corrosiveness becomes uniform, and the formation of macroscopic patterns is suppressed. In the titanium ring of this embodiment, for example, as shown in Figure 2, the average grain size difference in the grain size distribution at multiple measurement positions selected in the circumferential direction to a depth of 1 mm in the radial direction of the titanium ring from the outer circumferential surface of the titanium ring is within 10 μm, and the σ difference is 0.1 or less.

[0036] In this embodiment, the titanium ring has a uniform metal structure throughout its entire circumferential direction, thus suppressing the occurrence of macroscopic patterns. To evaluate the uniformity of the metal structure, in this embodiment, five measurement positions are set at a depth of 1 mm in the radial direction from the outer surface of the titanium ring and at equal intervals in the circumferential direction, and these are used as evaluation positions for the metal structure. In detail, to calculate the average grain size difference and σ difference, the grain size distribution is obtained at five measurement positions, each equally spaced in the circumferential direction and 1 mm in the radial direction from the outer surface of the titanium ring. The five measurement positions are set at five equally spaced positions in the circumferential direction from an arbitrary reference position. This reference position is included in the measurement positions. Therefore, when viewed from the central axis direction of the titanium ring, the measurement positions are determined at a central angle pitch of 72 degrees. At each measurement position, the observation surface is the surface chemically polished up to 1 mm in the radial direction from the outer surface of the titanium ring. Chemical polishing is performed by the following method: the measurement surface is polished using a wet polishing machine with emery paper of #120 to #1500, then mechanically and chemically polished using a colloidal silica suspension, and finally, the surface is etched with an aqueous solution of 3% hydrofluoric acid and 5% nitric acid. An EBSD pattern is obtained by electron backscatter diffraction with a step size of 1.0 μm while scanning the electron beam with a scanning electron microscope over a 1 mm × 1 mm field of view of the observation surface. Based on the acquired EBSD pattern, the average grain size and standard deviation of grain size are determined using TSL Solutions' OIM Analysis software (Ver. 8.1.0). In this process, boundaries with an orientation difference of 15° or more are recognized as grain boundaries, and if a region enclosed by a grain boundary contains two or more pixels, this region is considered a grain. The average grain size is defined as the arithmetic mean of the area-based equivalent diameters of the obtained grains. The standard deviation of grain size is calculated by approximating the grain size distribution with a log-normal distribution function.

[0037] The difference between the maximum and minimum average grain size values ​​among the five measurement points measured using the method described above is defined as the average grain size difference. In this embodiment, the average grain size difference is 10 μm or less. If the average grain size difference is 10 μm or less, the metal structure can be evaluated as uniform in the circumferential direction, resulting in a titanium ring with suppressed macroscopic patterns. Furthermore, even during copper foil manufacturing, the uniform abrasiveness and corrosiveness can suppress the occurrence of macroscopic patterns. Preferably, the average grain size difference is 8 μm or less, or 5 μm or less. The lower limit of the average grain size difference is 0 μm.

[0038] Furthermore, in this embodiment, the difference (σ difference) between the maximum and minimum values ​​of the five standard deviations of crystal grain sizes calculated at the five measurement positions is 0.1 μm or less. When the σ difference is 0.1 μm or less, the metal structure can be evaluated as uniform in the circumferential direction, resulting in a titanium ring with suppressed macroscopic patterns. Moreover, even during copper foil manufacturing, the polishability and corrosiveness are uniform, thus suppressing the occurrence of macroscopic patterns. Preferably, the σ difference is 0.08 μm or less, or 0.05 μm or less. The lower limit of the σ difference is 0 μm.

[0039] As long as the average grain size difference and σ difference are within the above range, the average grain size is not particularly limited. However, the practical upper limit of the average grain size is 300 μm, and the practical lower limit is 1 μm.

[0040] The α-phase crystal structure is hexagonal close-packed (hcp), and its hardness varies greatly depending on the crystal orientation, particularly the c-axis direction of the hcp relative to the radial direction. Therefore, to ensure uniform polishability on the titanium ring surface, it is desirable to align the c-axis of the hcp relative to the radial direction as much as possible. Generally, when pure titanium is rolled in one direction, it mainly forms a Split-TD-texture where the texture is oriented in the width direction of the titanium ring, but the crystal orientation also changes if the amount of rolling and the rolling temperature change during rolling. Furthermore, when manufacturing titanium rings from conventional titanium sheets, the crystal orientation also changes significantly in the welded areas.

[0041] Figure 3 is an example of a graph showing the area ratio of crystal grains for each angle between the radial direction and the c-axis of hcp at two different measurement positions in the circumferential direction at a depth of 1 mm radially from the outer surface of a conventional titanium ring. Figure 4 is an example of a graph showing the area ratio of crystal grains for each angle between the radial direction and the c-axis of hcp at two different measurement positions in the circumferential direction at a depth of 1 mm radially from the outer surface of a titanium ring according to an embodiment of the present invention.

[0042] In conventional titanium rings, the crystal orientation distribution can vary significantly depending on the measurement position in the circumferential direction, as shown in Figure 3. In the graph shown in Figure 3, the angle θ between the radial direction and the c-axis at which the area ratio is maximized differs between the first and second measurement positions, and the distribution of the area ratio also differs at each measurement position. In other words, the direction of texture accumulation differs between the first and second measurement positions. When the distribution of the angle between the radial direction and the c-axis (angle θ) (texture distribution) differs significantly depending on the measurement position in the circumferential direction, it can lead to differences in the degree of corrosion on the titanium ring surface during copper foil manufacturing, making it easier for macroscopic patterns to occur. However, if the texture distribution is uniform, the corrosiveness becomes uniform, and the occurrence of macroscopic patterns is suppressed. In the titanium ring of this embodiment, as shown in Figure 4, for example, when the crystal grains are divided at the measurement position according to the angle between the radial direction and the c-axis of hcp, the angular difference that maximizes the area ratio for each division is within 10 degrees, and the square of the area ratio difference for each angular range is 0.05 or less.

[0043] The angle θ between the c-axis of hcp and the radial direction is obtained by cutting a sample for analysis from the above measurement position on the titanium ring and chemically polishing the surface of the sample to a depth of 1 mm. The crystal orientation of the surface after chemical polishing is obtained by EBSD analysis. For example, using EBSD, a 1 mm × 1 mm area is scanned with an EBSD pattern at intervals of a step size of 1.0 μm. Based on the acquired EBSD pattern, the area fraction for each 5-degree interval of the angle θ between the c-axis of hcp and the radial direction is calculated using OIM Analysis software (Ver. 8.1.0) from TSL Solutions. For example, the sum of the area fractions of crystal grains with an angle θ of 0 degrees or more and less than 5 degrees is plotted at the 5-degree position.

[0044] At each of the above five measurement positions, for every 5 degrees of the angle formed between the radial direction and the c-axis of the hcp, calculate the area ratio of the crystal grains tilted at each angle, and obtain the angle θ when the area ratio at each measurement position is maximized. In this embodiment, the difference between the maximum value and the minimum value of the five angles θ calculated at the five measurement positions is 10 degrees or less. Preferably, the angle difference is 5 degrees or less. The lower limit of the angle difference is 0 degrees.

[0045] Also, in this embodiment, at the above five measurement positions, the squared value of the area ratio difference of the crystal grains tilted at each angle is 0.05 or less. For example, referring to FIG. 3, for the first measurement position and the second measurement position, calculate the difference in area ratio for each angle θ of the c-axis with respect to the radial direction. For example, if the area ratio of the crystal grains tilted 20 degrees with respect to the radial direction at the first measurement position is A1 and the area ratio of the crystal grains tilted 20 degrees with respect to the radial direction at the second measurement position is A2, then the area ratio difference of the crystal grains with an angle θ of 20 degrees is A1 - A2, and the squared value of the area ratio difference is (A1 - A2) 2 is. For all measurement positions, calculate the squared value (A θm - A θn ) 2 every 5 degrees. (A θm - A θn ) 2 where θ is the angle formed between the radial direction and the c-axis of the hcp, and m, n are symbols 1 to 5 representing each of the five measurement positions. In this embodiment, the maximum value of all calculated (A θm - A θn ) 2 is 0.05 or less. The maximum value of (A θm - A θn ) 2 is preferably 0.04 or less, more preferably 0.03 or less.

[0046] The angle formed between the radial direction and the c-axis of the hcp is 10 degrees or less, and (A θm - A θn ) 2When the maximum value is 0.05 or less, the titanium ring has a uniform texture in the circumferential direction and suppressed macroscopic patterns. Furthermore, even during copper foil manufacturing, the uniform abrasive and corrosive properties can suppress the occurrence of macroscopic patterns.

[0047] There are no particular restrictions on the diameter of the titanium ring. However, in order to manufacture copper foil with high manufacturing efficiency, the diameter of the titanium ring is, for example, 1 meter or more, or 2 meters or more.

[0048] The wall thickness of the titanium ring according to this embodiment is not particularly limited, but since the wall thickness decreases with the use of the copper foil manufacturing drum, it is preferable that the wall thickness of the titanium ring be 4.0 mm or more, and may be 6.0 mm or more. The upper limit of the wall thickness of the titanium ring is not particularly limited, but for example, it is 15.0 mm.

[0049] The titanium ring according to the embodiment described above has the above chemical composition, has no seams, and the difference between the maximum and minimum values ​​of the average grain size of the grain size distribution obtained at five measurement positions, which are 1 mm deep radially from the outer surface of the titanium ring and equally spaced in the circumferential direction of the titanium ring, is 10 μm or less, and the difference between the maximum and minimum values ​​of the standard deviation of the log-normal distribution function of the grain size distribution is 0.1 or less. Furthermore, in the graph showing the area ratio of crystal grains for each angle between the radial direction and the c-axis of the hexagonal close-packed structure at each of the five measurement positions, the difference between the maximum and minimum values ​​of the angle where the area ratio is maximized is within 10 degrees, and the maximum value of the square of the area ratio difference for each angle is 0.05 or less. Therefore, the metallic structure of the titanium ring according to this embodiment is uniform. As a result, macroscopic patterns are suppressed, and even during copper foil manufacturing, the polishability and corrosiveness are uniform, thus suppressing the occurrence of macroscopic patterns.

[0050] As described above, the titanium ring according to one embodiment of the present invention is intended to be used as a material for a drum for copper foil manufacturing (copper foil manufacturing drum). Therefore, the titanium ring according to this embodiment can also be said to be a titanium ring for a copper foil manufacturing drum. When used in a copper foil manufacturing drum, the outer circumferential surface of the titanium ring constitutes the cylindrical surface of the copper foil manufacturing drum.

[0051] <Copper foil manufacturing drum> As shown in Figure 5, the copper foil manufacturing drum 20 according to this embodiment is used by being incorporated into a copper foil manufacturing apparatus as shown in Figure 6. The copper foil manufacturing drum 20 in Figure 5 has a cylindrical inner drum 21 and a titanium ring 22 attached to the outer circumferential surface of the inner drum 21.

[0052] The inner drum 21 can be any known material, and its material does not have to be titanium; for example, it may be mild steel or stainless steel. The titanium ring 22 is a titanium ring according to the embodiment and is press-fitted into the inner drum 21.

[0053] The copper foil manufacturing drum 20 according to this embodiment is a copper foil manufacturing drum manufactured using the titanium ring according to this embodiment. Because the copper foil manufacturing drum 20 according to this embodiment uses the titanium ring according to this embodiment on the surface of the drum where the copper foil is deposited, the occurrence of macro patterns can be suppressed.

[0054] <How to manufacture a titanium ring> A preferred method for manufacturing a titanium ring according to an embodiment of the present invention will be described below. The manufacturing method described below is merely an example, and the manufacturing method of a titanium ring according to an embodiment of the present invention is not limited thereto.

[0055] The titanium ring according to the embodiment is manufactured, for example, by ring rolling a ring-shaped titanium ring material. Ring rolling is a method of manufacturing a ring-rolled material by, for example, bringing a main roll and a mandrel roll into contact with the outer and inner circumferential surfaces of the ring material, respectively, rotating the main roll and mandrel roll around their respective central axes, clamping and pressing the ring material radially, and clamping and pressing the ring material with a pair of axial rolls in the direction of the ring material's central axis. The titanium ring according to the embodiment is manufactured by heating a ring material having a predetermined chemical composition to below its β transformation point, ring rolling it with a rolling rate of 60% or more and a rolling speed of 10 m / min or more, and then heat-treating the ring material after ring rolling.

[0056] (Heating temperature: Below the β-transformation point) A ring material having a chemical composition by mass% containing Fe: 0.010~0.045%, O: 0.01~0.20%, Cu: 0~1.0%, Al: 0~2.0%, Sn: 0~2.0%, Zr: 0~2.0%, C: less than 0.08%, and N: 0.05% or less, with the remainder being Ti and impurities, is heated to a temperature of 500°C or higher and below the β-transformation point. The ring material may be manufactured by known methods. Below 500°C, the deformation resistance during rolling becomes too high, making it difficult to roll to a stable plate thickness.

[0057] When titanium is heated above its β-transformation point and then ring-rolled, a texture called T-texture is formed, in which the c-axis of hcp grains is oriented in the width direction of the titanium ring. When T-texture is formed, a band-like structure is created, and the grain size and texture become uneven. On the other hand, if the heating temperature is less than 500°C, it is not possible to manufacture titanium rings of the desired size by ring rolling. A heating temperature of 700°C or higher is preferable. At 700°C or higher, the temperature of the titanium material does not become too low in the latter half of ring rolling, eliminating the need for reheating. Reheating can cause the amount of strain to be unstable in different parts, resulting in variations in grain size. By setting the heating temperature to 700°C or higher, ring rolling can be completed without reheating, the amount of strain is stable, and variations in grain size can be suppressed.

[0058] (Rolling ratio: 60% or more) If the reduction ratio is low, nucleation will be reduced during the heat treatment process after ring rolling, resulting in variations in grain size. Therefore, the rolling ratio should be 60% or higher. However, if reheating is performed and ring rolling is carried out two or more times, the rolling ratio in the final ring rolling should be 60% or higher.

[0059] (Rolling speed: 10 m / min or more) If the rolling speed during ring rolling is too slow, recrystallization may occur during the non-rolling phase, or the amount of strain in the circumferential direction may become unstable due to processing heat generation and cooling during ring rolling. As a result, even after subsequent heat treatment, the grain size and texture may not be uniform. Therefore, the rolling speed should be 10 m / min or higher. This allows the grain size and texture of the titanium ring after the heat treatment process following ring rolling to be determined to be the desired values.

[0060] Preferably, the rolling temperature during the latter half of ring rolling, i.e., when rolling the final 10-30% of the total rolling rate, should be 650°C or lower. This further stabilizes the grain size distribution and crystal orientation.

[0061] The titanium rings, after ring rolling, may be subjected to spinning to adjust their width as needed.

[0062] (Heat treatment process) It is preferable to perform a heat treatment process after ring rolling. The heat treatment temperature should be, for example, 600°C or higher and 800°C or lower, and the heat treatment time should be 1 minute or higher and 60 minutes or lower. This makes it possible to achieve a uniform grain size distribution. The heat treatment may be carried out in an air atmosphere, an inert atmosphere, or a vacuum atmosphere. However, if oxide scale forms on the titanium ring, the oxide scale must be removed. The removal of oxide scale is not particularly limited and may be carried out by, for example, shot blasting, shot blasting followed by pickling, or by machining such as polishing or cutting. However, in order to avoid introducing strain into the titanium ring, it is preferable to remove the oxide scale by machining. Furthermore, the annealing method is not particularly limited and may be a continuous heating method or a batch heating method.

[0063] Post-processing may include removal of oxide scale and other contaminants, as well as cleaning, and can be applied as needed. Additionally, titanium ring straightening may be performed as a post-processing step. The above describes an example of a method for manufacturing a titanium ring according to an embodiment.

[0064] The present invention has been described with reference to these embodiments. However, the technical scope of the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. [Examples]

[0065] The embodiments of the present invention will be described in detail below with reference to examples. The examples shown below are merely examples of the present invention, and the present invention is not limited to the examples below.

[0066] Titanium rings with a diameter of 3000 mm, a wall thickness of 15 mm, and a width of 1500 mm were manufactured by ring rolling and heat treatment of titanium materials with the chemical composition shown in Table 1 and different thicknesses, under the conditions shown in Table 2. Therefore, titanium rings of the above sizes were manufactured by changing the rolling ratio according to the thickness. In Table 1, "-" indicates that the level is below the detection limit.

[0067] [Table 1]

[0068] [evaluation] Chemical composition analysis, grain size distribution analysis, and crystal orientation analysis were performed on each manufactured outer skin.

[0069] In the chemical composition analysis, O and N were measured using an oxygen-nitrogen simultaneous analyzer, employing inert gas melting, thermal conductivity, and infrared absorption spectroscopy. C was measured using an infrared absorption spectroscopy with a carbon-sulfur simultaneous analyzer. H was measured using inert gas melting and infrared absorption spectroscopy. Elements such as Fe and Cu were measured by ICP emission spectroscopy.

[0070] For each example, five measurement positions were determined at equal intervals in the circumferential direction on the outer surface of the titanium ring, and the outer surface of each measurement position was chemically polished radially to a depth of 1 mm. After chemical polishing, an electron beam was irradiated onto a 1 mm × 1 mm area of ​​the surface with a step width of 1 mm, and the average grain size and standard deviation of the grain size were determined using OIM Analysis software from TSL Solutions based on the acquired EBSD pattern. The average grain size was defined as the average diameter equivalent to a circle based on area. In addition, the standard deviation of the log-normal distribution function of the grain size distribution was determined. From the average grain size and standard deviation of the grain size at each measurement position, the difference in grain size and the difference in standard deviation (σ difference) were calculated.

[0071] For each example of titanium ring, a (0001) pole figure was obtained from the EBSD pattern at the five measurement points mentioned above. From the obtained pole figures, a graph was created showing the area ratio of crystal grains for each angle θ between the radial direction and the c-axis of the hexagonal close-packed structure, and the maximum value of the angle θ between the c-axis of hcp and the circumferential direction (peak position of crystal grain accumulation) was calculated. The angle θ interval in the created graph was set to 5 degrees.

[0072] To evaluate the macro-pattern, the outer surface of each manufactured titanium ring was visually inspected. After etching the ring surface with a 10% nitric acid and 5% hydrofluoric acid solution, visual inspection was performed, and streak-like patterns of 3 mm or longer were defined as macro-patterns at a rate of 0.05 patterns / cm². 2If the following conditions are met, the macro pattern evaluation result will be A (excellent), 0.05 particles / cm. 2 Super, 0.2 pieces / cm 2 If the result is less than 0.2 particles / cm, the macro pattern evaluation result is B (good), 0.2 particles / cm. 2 If the above conditions were met, the macro pattern evaluation result was set to C (poor), and A or B was considered acceptable. The results are shown in Table 2.

[0073] [Table 2]

[0074] As shown in Table 2, examples No. 1-4, 6, 7, 9-11, and 16-18 had titanium rings with the chemical composition described above, and the macro-pattern evaluation results were satisfactory. In particular, examples No. 1-4, 6, 7, and 9-11 showed extremely good macro-pattern evaluation results.

[0075] In example No. 5, the excessive Fe content resulted in excessive β-phase precipitation, causing the average grain size difference and σ difference to fall outside the range of the present invention. Consequently, the evaluation results for the macroscopic pattern were unsatisfactory. In example No. 8, the excessive Cu content resulted in excessive precipitation of Ti2Cu and the β phase, causing the average grain size difference and σ difference to fall outside the range of the present invention. As a result, the evaluation results for the macroscopic pattern were poor. In example No. 12, the excessive oxygen content resulted in the titanium ring becoming excessively hard, making it impossible to uniformly polish the surface of the titanium ring, and thus the macro-pattern evaluation result was poor. In example No. 13, the heating temperature during ring rolling was too high, resulting in the formation of a T-texture. The maximum values ​​of the peak angle difference and the squared difference in area ratios across each angular range fell outside the scope of the present invention. As a result, the evaluation of the macro-pattern was unsatisfactory. In example No. 14, the final rolling ratio during ring rolling was too low, resulting in insufficient nucleation. Consequently, the maximum values ​​of the average grain size difference, peak angle difference, and the squared difference in area ratio within each angular range fell outside the scope of the present invention. As a result, the evaluation of the macroscopic pattern was unsatisfactory. In example No. 15, the rolling speed during ring rolling was too low, causing recrystallization during the non-rolling phase, resulting in an average grain size difference outside the range of the present invention. Consequently, the evaluation results for the macroscopic pattern were unsatisfactory. [Explanation of Symbols]

[0076] 1 Copper foil manufacturing equipment 2. Copper foil manufacturing drum 10 Electrolytic cell 30 Electrode plate 40 Winding section 50 Guide Roll 60 reel rolls A Copper foil 20 Copper foil manufacturing drums 21 Inner Drum 22 Titanium Rings

Claims

1. It is a titanium ring, The aforementioned titanium ring is, by mass%, Fe: 0.010-0.045%, O: 0.010 to less than 0.200%, Cu: 0 to 1.00%, Al: 0-2.00%, Sn: 0-2.00%, Zr: 0 to 2.00%, C: 0-0.080% N: 0-0.050%, and, It contains H: 0 to 0.0150%, The chemical composition consists of Ti and impurities as the remainder. It has no seams, The difference between the maximum and minimum values ​​of the average grain size of the grain size distribution obtained at five measurement positions, each equally spaced in the circumferential direction of the titanium ring and extending 1 mm from the outer surface of the titanium ring, is 10 μm or less, and the difference between the maximum and minimum values ​​of the standard deviation of the log-normal distribution function of the grain size distribution is 0.1 or less. A titanium ring in which, in a graph showing the area ratio of crystal grains for each angle between the radial direction and the c-axis of the hexagonal close-packed structure at each of the five measurement positions, the difference between the maximum and minimum values ​​of the angle in which the area ratio is maximized is within 10 degrees, and the maximum value of the square of the area ratio difference for each angle is 0.05 or less.

2. A cylindrical inner drum, A copper foil manufacturing drum comprising the titanium ring described in claim 1, which is attached to the outer circumferential surface of the inner drum.

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