Metal wire, saw wire and metal mesh

Abstract

To provide a metal wire in which deformation or disconnection of a wire is less likely to occur.SOLUTION: A metal wire is a tungsten wire or a tungsten alloy wire. An amount of alkali metal existing on a surface of the metal wire is greater than 0.0 μg in a metal wire 1 g and less than or equal to 2.0 μg. A wire diameter of the metal wire is less than or equal to 40 μm.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a metal wire, a saw wire and a metal mesh. [Background technology]

[0002] Conventionally, products using tungsten, which has characteristics such as a high melting point and high hardness, are known. For example, Patent Document 1 discloses the use of a tungsten-rhenium alloy wire as a medical needle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2010 / 100808 [Non-patent literature]

[0004] [Non-Patent Document 1] "Tungsten and Molybdenum Technical Data", Revised 3rd Edition, Japan, Tungsten and Molybdenum Industry Association, February 25, 2009, p.116 Summary of the Invention [Problem to be solved by the invention]

[0005] Metal wires such as tungsten rhenium alloy wires are generally wound around bobbins and stored before being processed into medical needles. As the storage period increases, the surface of the metal wire oxidizes and the metal wires stick together (see, for example, Non-Patent Document 1). As a result, stress is generated in the metal wire when it is pulled out from the bobbin, making it more likely to become bent or break.

[0006] Therefore, an object of the present invention is to provide a metal wire that is less likely to become twisted or break, and a saw wire and a metal mesh that include the metal wire. [Means for solving the problem]

[0007] In order to achieve the above object, a metal wire according to one embodiment of the present invention is a tungsten wire or a tungsten alloy wire, in which the amount of alkali metal present on the surface of the metal wire is greater than 0.0 μg and not more than 2.0 μg per 1 g of the metal wire, and the wire diameter of the metal wire is not more than 40 μm.

[0008] A saw wire according to an aspect of the present invention includes the metal wire according to the above aspect.

[0009] A metal mesh according to one aspect of the present invention includes the metal wire according to the above aspect. Effect of the Invention

[0010] According to the present invention, it is possible to provide a metal wire which is less prone to bending and breakage. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a graph showing the relationship between the thickness of an oxide film formed on the surface of a metal wire according to an embodiment and the number of days the metal wire is left standing for each amount of alkali metal present on the surface. [Diagram 2] FIG. 2 is a graph showing the relationship between the thickness of an oxide film formed on the surface of a metal wire according to an embodiment and the amount of alkali metal present on the surface for each number of days that the metal wire is left exposed. [Diagram 3] FIG. 3 is a flowchart showing a method for manufacturing a metal wire according to an embodiment. [Figure 4] FIG. 4 is a flowchart showing a method for measuring the amount of alkali metal present on the surface of a metal wire according to an embodiment. [Diagram 5] FIG. 5 is a perspective view showing a metal wire according to an embodiment and a metal mesh woven using the metal wire. [Figure 6] FIG. 6 is a schematic diagram showing a coiling process for a filament coil using a metal wire according to the embodiment. [Figure 7]FIG. 7 is a perspective view showing a metal wire rewinding device according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the metal wire according to the embodiment of the present invention will be described in detail with reference to the drawings. Note that each of the embodiments described below shows a specific example of the present invention. Therefore, the numerical values, shapes, materials, components, arrangement and connection forms of the components, steps, order of steps, etc. shown in the following embodiments are merely examples and are not intended to limit the present invention. Therefore, among the components in the following embodiments, components that are not described in the independent claims will be described as optional components.

[0013] In addition, each figure is a schematic diagram and is not necessarily illustrated precisely. Therefore, for example, the scales in each figure do not necessarily match. In addition, in each figure, substantially the same configurations are given the same reference numerals, and duplicated explanations are omitted or simplified.

[0014] (Embodiment) [Metal wire] First, the configuration of the metal wire according to the embodiment will be described.

[0015] The metal wire according to the present embodiment is a tungsten wire or a tungsten alloy wire. That is, the metal wire is a metal wire containing tungsten (W) as a main component. The tungsten content of the metal wire is, for example, 90wt% or more. Here, the content is the ratio of the mass of a metal element (for example, tungsten) to the mass of the metal wire. The tungsten content may be 95wt% or more, 99wt% or more, or 99.9wt% or more.

[0016] The tungsten wire is a pure tungsten wire made of pure tungsten, or a doped tungsten wire made of tungsten doped with an element other than tungsten. In this specification, pure tungsten means that the tungsten content is 99.95 wt% or more. The pure tungsten wire contains unavoidable impurities.

[0017] The element doped into the doped tungsten wire (hereinafter referred to as the doping element) is, for example, potassium (K), but may also be thorium (Th) or cerium (Ce). The potassium content is, for example, 0.01 wt% or less. In this case, the potassium content may be 0.003 wt% or more. Also, the potassium content may be 0.005 wt% or more or less.

[0018] The doping element (e.g., potassium) is present at the grain boundaries of tungsten. In other words, the majority of the doping element is present inside the metal wire. Therefore, the amount of the doping element can be substantially ignored in the method for measuring the amount of alkali metal present on the surface of the metal wire (described in detail later).

[0019] The tungsten alloy wire is a metal wire made of an alloy of tungsten and a metal element. The metal element (hereinafter, described as alloy element) used in the alloy with tungsten is, for example, rhenium (Re). Alternatively, the alloy element may be ruthenium (Ru), osmium (Os) or iridium (Ir). The tungsten alloy wire may contain only one type of alloy element, or may contain two or more types of alloy elements. The content of the alloy element in the tungsten alloy wire is, for example, 0.1wt% or more and 10wt% or less. Alternatively, the content of the alloy element may be 0.5wt% or more and 5wt% or less. As an example, the content of the alloy element is 1wt%, but may be 3wt%.

[0020] An alkali metal is present on the surface of the metal wire. The alkali metal is, for example, sodium (Na) or potassium. Although the details will be described later, the alkali metal is a residual element contained in the solution used in manufacturing the metal wire.

[0021] Although details will be described later, the inventors of the present application have found that the alkali metal present on the surface of the metal wire is a cause of oxidation of the metal wire surface. In the metal wire according to the present embodiment, the amount of alkali metal present on the surface is equal to or less than a predetermined value, so that oxidation of the metal wire surface is suppressed.

[0022] Specifically, the amount of alkali metal present on the surface of the metal wire is 2.0 μg or less per 1 g of the metal wire. The amount of alkali metal present on the surface of the metal wire may be 1.0 μg or less per 1 g of the metal wire. The amount of alkali metal present on the surface of the metal wire may be 0.5 μg or less per 1 g of the metal wire.

[0023] From the viewpoint of suppressing oxidation between metal wires, the smaller the amount of alkali metal present on the surface of the metal wire, the better. However, it is difficult to reduce the amount to zero. In other words, the amount of alkali metal present on the surface of the metal wire is greater than 0.0 μg per 1 g of metal wire. For example, the amount of alkali metal present on the surface of the metal wire may be 0.1 μg or more per 1 g of metal wire.

[0024] The wire diameter of the metal wire is, for example, 40 μm or less. The wire diameter may be 30 μm or less, or 20 μm or less. For example, the wire diameter of the metal wire may be 15 μm or less, or 13 μm or less. The wire diameter of the metal wire may be 10 μm or less. The wire diameter of the metal wire may be as small as the processing limit. For example, the lower limit of the wire diameter of the metal wire may be 5 μm.

[0025] The smaller the wire diameter, the more likely the wire will become bent or broken due to stress generated in the metal wire when removing the metal wires that have been stuck together. Therefore, it is expected that the smaller the wire diameter of the metal wire, the more likely it is that sticking will be suppressed.

[0026] [Relationship between the amount of alkali metal and adhesion between metal wires] Next, the relationship between the amount of alkali metal present on the surface of the metal wire and adhesion between the metal wires according to this embodiment will be described.

[0027] When a metal wire containing tungsten as a main component is stored in air, the surface is oxidized and a tungsten oxide film is formed on the surface. Metal wires are generally stored wound around bobbins, etc., and at this time, the surfaces of the metal wires are in close contact with each other. Therefore, when an oxide film is formed on the surface, the surfaces of the metal wires stick together. As described in Non-Patent Document 1, in the case of ultra-fine wires with a wire diameter of about 10 μm, the wires stick together due to oxidation to such an extent that the metal wires cannot be drawn out.

[0028] The inventors of the present application have investigated the causes of oxidation of metal wires and the means for suppressing this oxidation, and have found that the alkali metal remaining on the surface is highly likely to be the cause of oxidation.

[0029] Fig. 1 is a graph showing the relationship between the thickness of the oxide film formed on the surface of the metal wire according to this embodiment and the number of days the metal wire was left exposed for each amount of alkali metal present on the surface. In Fig. 1, the horizontal axis represents the number of days the metal wire was left exposed in a room temperature environment (25°C) when the date of manufacture of the metal wire is set as day 0. The vertical axis represents the thickness of the oxide film on the metal wire. The thickness of the oxide film on the metal wire was measured by cutting the metal wire at a cross section perpendicular to the wire axis direction and examining the area near the surface with an electron microscope.

[0030] The comparative example, example 1, example 2, and example 3 shown in FIG. 1 have different amounts of alkali metal present on the surface of 1g of metal wire. Specifically, the comparative example, example 1, example 2, and example 3 have 4.0μg, 2.0μg, 1.0μg, and 0.5μg amounts of alkali metal present on the surface of 1g of metal wire, respectively. The comparative example and examples 1 to 3 have the same parameters except for the amount of alkali metal present on the surface. For example, the wire diameter of each of the comparative example and examples 1 to 3 is 16μm. Also, each of the comparative example and examples 1 to 3 is a doped tungsten wire doped with 60ppm of potassium.

[0031] The manufacturing methods for the comparative example and examples 1 to 3 will be described later with reference to Fig. 3. Also, the method for measuring the amount of alkali metal present on the surface will be described later with reference to Fig. 4.

[0032] 1, the longer the period of storage, the more the oxidation of the surface progresses and the thickness of the oxide film increases in the Comparative Example and Examples 1 to 3. Note that the thickness of the oxide film after 12 months in Examples 1 to 3 is an estimated value based on the thickness of the Comparative Example after 12 months and the degree of increase in thickness up to 6 months in each of Examples 1 to 3.

[0033] As can be seen from a comparison between the Comparative Example and Examples 1 to 3, the smaller the amount of alkali metal present on the surface of the metal wire, the more difficult it is for an oxide film to form. This is presumably based on the following principle.

[0034] Alkali metals exist as hydroxides on the surface of the metal wire. Hydroxides of alkali metals are hygroscopic. Therefore, when an alkali metal (specifically, its hydroxide) exists on the surface of the metal wire, the alkali metal is more likely to absorb moisture in the air. This makes it easier for moisture to adhere to the surface of the metal wire, and the adhered moisture reacts with tungsten to form tungsten oxide on the surface. The greater the amount of alkali metal, the greater the amount of moisture absorbed, making it easier for tungsten oxide to form and resulting in a thicker oxide film.

[0035] When the thickness of the oxide film was measured when the metal wires were stuck together, it was found to be 20 nm or more. Specifically, when the oxide film was 20 nm or more thick, the metal wires stuck together, and the frequency of the wire bending and breakage increased, inducing a decrease in yield. When the oxide film was less than 20 nm thick, the wire hardly bent or broke.

[0036] In the comparative example, when the storage period exceeded 6 months, the thickness of the oxide film exceeded 20 nm, and adhesion of the metal wire occurred. In other words, it can be said that the product life of the comparative example was 6 months or less. On the other hand, in Examples 1 to 3, the thickness of the oxide film was 10 nm or less after 6 months. Therefore, it is estimated that the thickness of the oxide film was 20 nm or less even after 12 months, and it is found that storage is possible without adhesion of the metal wire for more than twice as long as that of the comparative example. In other words, Examples 1 to 3 can extend the product life by more than twice as long as that of the comparative example.

[0037] Fig. 2 is a graph showing the relationship between the thickness of the oxide film formed on the surface of the metal wire according to the present embodiment and the amount of alkali metal present on the surface for each number of days the metal wire is left exposed. In Fig. 2, the horizontal axis represents the amount of alkali metal present on the surface of the metal wire. The vertical axis represents the thickness of the oxide film on the metal wire. Fig. 2 shows a graph drawn using the same data as the graph in Fig. 1. Therefore, in the graph for a storage period of 12 months, the plots for amounts of alkali metal of 0.5 μg, 1.0 μg, and 2.0 μg are estimated values.

[0038] As shown in Fig. 2, when the amount of alkali metal in 1g of metal wire is 4.0μg (Comparative Example), the amount of alkali metal is twice as much as when it is 2.0μg (Example 1), and the thickness of the oxide film is about twice as much at each of the time points after 3 months, 6 months, and 12 months. On the other hand, when the amount of alkali metal in 1g of metal wire is 1.0μg (Example 2), the amount of alkali metal is half that of when it is 2.0μg (Example 1), but the thickness of the oxide film is less than half at each of the time points after 3 months, 6 months, and 12 months. In other words, by making the amount of alkali metal in 1g of metal wire 1.0μg or less, it is possible to further suppress the oxidation of the surface.

[0039] As described above, by setting the amount of alkali metal present on the surface of the metal wire to 2.0 μg or less, oxidation of the surface of the metal wire can be suppressed, and adhesion between the surfaces can be suppressed. By setting the amount of alkali metal to 1.0 μg or less, adhesion between the surfaces can be further suppressed.

[0040] In the above Comparative Example and Examples 1 to 3, the doped tungsten wire doped with potassium is shown, but the same tendency is obtained in any case of the doped element other than potassium, the pure tungsten wire, and the tungsten alloy wire. This is because in any case, tungsten is contained as the main component, and an oxide film with tungsten is formed on the surface. In other words, in any case of the doped tungsten wire other than potassium, the amount of alkali metal present on the surface of the metal wire may be 2.0 μg (or 1.0 μg or 0.5 μg) or less per 1 g of the metal wire. As a result, as in the case of the potassium doped tungsten wire, the formation of the oxide film is suppressed, and the adhesion between the metal wires is suppressed. Therefore, the doped tungsten wire, the pure tungsten wire, and the tungsten alloy wire that are less likely to cause wire curling and breakage are realized.

[0041] [Manufacturing method] Next, a method for manufacturing a metal wire according to the present embodiment will be described with reference to Fig. 3. Fig. 3 is a flowchart showing the method for manufacturing a metal wire according to the present embodiment.

[0042] As shown in Fig. 3, first, an ingot of tungsten or tungsten alloy is prepared (S10). Specifically, an aggregate of pure tungsten powder, an aggregate of doped tungsten powder, or an aggregate of tungsten powder and alloy metal powder (e.g., rhenium powder) is prepared. The aggregate of powder is pressed and sintered to produce an ingot. The average particle size of each powder is, for example, in the range of 3 μm to 4 μm.

[0043] Next, the produced ingot is subjected to swaging (S11). Specifically, the ingot is forged and compressed from the periphery to be stretched, thereby forming a wire-shaped tungsten wire or tungsten alloy wire. Note that rolling may be performed instead of swaging.

[0044] For example, by repeatedly performing swaging, an ingot with a diameter of about 15 mm to about 25 mm is formed into a tungsten wire or tungsten alloy wire with a wire diameter of about 3 mm. By performing annealing in the middle of the swaging process, workability in the subsequent processes is ensured. For example, annealing at 2400°C is performed when the diameter is in the range of 8 mm to 10 mm.

[0045] Next, tungsten wire or tungsten alloy wire is drawn (S12). Specifically, first, tungsten wire or tungsten alloy wire is heated, and oxide layer is formed on the surface. For example, tungsten wire or tungsten alloy wire is directly heated at a heating temperature of 900°C using a burner or the like. By forming oxide layer on the surface, it is possible to suppress the occurrence of wire breakage during the subsequent wire drawing process.

[0046] In the wire drawing step (S12), the tungsten wire is hot drawn using one wire drawing die. That is, the tungsten wire is drawn (thinned) while being heated. The hot wire drawing is repeated while changing the wire drawing die. The cross-sectional area reduction rate of the tungsten wire by one hot wire drawing using one wire drawing die is, for example, 10% or more and 40% or less. In the hot wire drawing, a lubricant in which graphite is dispersed in water may be used.

[0047] In the repeated hot wire drawing, a wire drawing die having a smaller hole diameter than the wire drawing die used in the previous hot wire drawing is used. The heating temperature is lowered as the number of repetitions increases. That is, the heating temperature is lower in the hot wire drawing using a small wire drawing die than in the hot wire drawing using a large wire drawing die. Note that electrolysis may be performed in the middle of the repeated hot wire drawing. The wire drawing dies used are carbide dies for wire diameters up to 0.38 mm, sintered diamond dies for wire diameters in the range of 0.38 mm to 0.18 mm, and single crystal diamond dies for wire diameters in the range of 0.18 mm to 0.010 mm.

[0048] After the wire drawing process, the tungsten wire or tungsten alloy wire is subjected to surface treatment (S13). The surface treatment is, for example, electrolytic polishing. Specifically, the tungsten wire or tungsten alloy wire after wire drawing and the counter electrode are immersed in an electrolytic solution, and a voltage is applied between the tungsten wire and the counter electrode. The electrolytic solution used in the electrolytic polishing is a solution containing an alkali metal element. For example, the electrolytic solution is an aqueous potassium hydroxide solution or an aqueous sodium hydroxide solution. The surface of the tungsten wire or tungsten alloy wire is polished by electrolytic polishing, so that oxides and graphite attached to the surface can be removed.

[0049] After the surface treatment, the surface of the tungsten wire or tungsten alloy wire is washed (S14). By washing the surface, the residue of the surface treatment (S13) that exists on the surface of the tungsten wire or tungsten alloy wire is washed off. Specifically, the tungsten wire or tungsten alloy wire after the surface treatment is immersed in washing water for a certain period of time, thereby washing the tungsten wire or tungsten alloy wire.

[0050] The cleaning water may be not only pure water but also an acidic solution, for example, a solution containing hypochlorous acid, a solution containing acetic acid, or a solution containing hydrochloric acid.

[0051] The cleaning water is, for example, pure water containing bubbles, microbubbles, or nanobubbles (hereinafter referred to as bubble water). Microbubbles or nanobubbles can be generated in pure water by a microbubble or nanobubble generator. Compared to pure water that does not contain either microbubbles or nanobubbles, bubble water has a higher cleaning power. Therefore, the amount of residue on the surface of the tungsten wire or tungsten alloy wire can be reduced.

[0052] By adjusting the bubble strength (specifically, the amount of bubbles per unit volume of bubbled water), it is possible to adjust the amount of alkali metal remaining on the surface of the metal wire. Specifically, by increasing the amount of bubbles, the cleaning power is increased and the amount of alkali metal remaining on the surface can be reduced. For example, Examples 1 to 3 shown in FIG. 1 are metal wires obtained by increasing the amount of bubbles in this order. Note that the Comparative Example is a metal wire obtained by cleaning using pure water containing no bubbles as cleaning water. The Comparative Example and Examples 1 to 3 are different from each other only in the cleaning (S14), and are metal wires manufactured through the same processes other than cleaning.

[0053] Through the above steps, a metal wire can be manufactured which is a tungsten wire or a tungsten alloy wire with a sufficiently reduced amount of alkali metal on the surface.

[0054] The surface treatment (S13) does not have to be electrolytic polishing. For example, the surface treatment may be a boiling treatment using a solution containing an alkali metal element. The solution used in the boiling treatment is, for example, a potassium hydroxide aqueous solution or a sodium hydroxide aqueous solution, similar to the electrolyte.

[0055] In addition, ultrasonic cleaning may be performed in the cleaning (S14). Specifically, the tungsten wire or tungsten alloy wire after the surface treatment may be immersed in cleaning water in which ultrasonic waves are generated by an ultrasonic generator (hereinafter, ultrasonic cleaning water). For example, by increasing the frequency or amplitude of ultrasonic waves, the cleaning power is increased and the amount of alkali metal remaining on the surface can be reduced.

[0056] The bubble water or ultrasonic cleaning water used for cleaning is collected and reused. That is, the bubble water or ultrasonic cleaning water may be circulated. Alternatively, the bubble water or ultrasonic cleaning water may be used in a so-called free-flowing manner without being collected. The free-flowing cleaning water does not contain the residue that falls off the surface by cleaning, so it can have a higher cleaning power than the circulating cleaning water. That is, it can further reduce the amount of alkali metal present on the surface of the tungsten wire or tungsten alloy wire after cleaning.

[0057] [Method of measuring alkali metals] Next, a method for measuring the amount of alkali metal present on the surface of a metal wire according to the present embodiment will be described with reference to Fig. 4. Fig. 4 is a flowchart showing a method for measuring the amount of alkali metal present on the surface of a metal wire according to the present embodiment.

[0058] As shown in Fig. 4, first, a metal wire to be measured is prepared (S20). Specifically, the metal wire is cut to a predetermined length, and the cut metal wire is prepared as a measurement object. The mass of the metal wire to be measured is measured and recorded. Note that the mass of the metal wire to be measured is not particularly limited, but by setting the mass to about 5 g, for example, the measurement can be performed easily and accurately.

[0059] Next, the metal wire to be measured and the pure water are placed in a container and sealed (S21). The container is, for example, a polyethylene bag. The amount of pure water is, for example, 5 cc. The bag is sealed after removing as much air as possible from inside so that the bag does not burst when the temperature is raised in the next process.

[0060] Next, the container is heated (S22). Specifically, the sealed bag containing the metal wire to be measured and the pure water is heated in boiling water for 60 minutes (water bath heating). As a result, the hydroxide of the alkali metal remaining on the surface of the metal wire to be measured is dissolved in the pure water in the bag.

[0061] After stopping the heating and cooling to room temperature (e.g., 25°C), the liquid in the container is sampled (S23). Specifically, 1 cc of the liquid in the container is sampled with a syringe with a needle, and solids mixed in the liquid are removed by filtering (S24).

[0062] Next, ion chromatography is performed on 0.25 cc of the filtered liquid (S25). As an analyzer for performing ion chromatography, for example, an ion chromatography analyzer ICS-1100 manufactured by DIONEX is used. As a cation exchange column, a Dionex IonPac CS12A column manufactured by Thermo Scientific is used.

[0063] Next, the amount of alkali metal in the filtered solution is calculated (S26). Specifically, the amount of alkali metal in the collected and filtered solution is calculated by comparing the peak area of ​​the chart obtained by ion chromatography with the peak area of ​​the chart obtained by ion chromatography for the standard solution. The amount of alkali metal present on the surface of the metal wire in 1 g of metal wire is calculated by multiplying the amount of alkali metal in the filtered solution by the solution ratio (= amount of pure water prepared / amount of filtered solution) and dividing the result by the mass measured in step S20. In other words, the amount of alkali metal X [unit: μg] present on the surface of the metal wire in 1 g of metal wire is calculated based on the following formula (1).

[0064] (1) X = Y × (Va ÷ Vb) ÷ Z

[0065] Here, Y is the amount of alkali metal obtained based on the peak area of ​​the chart [unit: μg]. Va is the amount of pure water prepared in step S21 [unit: cc]. Vb is the amount of solution filtered in step S24 [unit: cc]. Z is the mass of the metal wire to be measured measured in step S20 [unit: g].

[0066] As the standard solution, for example, Cat. No. 07197-96 Cation Mixed Standard Solution manufactured by Kanto Chemical Co., Ltd. The analytical device, column, and standard solution used in ion chromatography are not particularly limited.

[0067] Through the above steps, the amount of alkali metal on the surface of the metal wire can be measured.

[0068] As described above, in the doped tungsten wire, the doping element (e.g., potassium) exists at the grain boundaries. In other words, since most of the doping element exists inside the metal wire, it can be considered that the doping element does not dissolve in the pure water in the heating process in step S22. It can be ignored as the liquid collected in step S23 does not substantially contain the doping element.

[0069] [Examples of metal wire usage] Next, an example of use of the metal wire according to the present embodiment will be described.

[0070] The metal wire according to the present embodiment can be used for various purposes. Fig. 5 is a perspective view showing a metal wire 1 according to the present embodiment and a metal mesh 10 woven using the metal wire 1.

[0071] 5, a manufactured metal wire 1 is generally stored wound around a bobbin (spool) 2. When a desired metal product is manufactured using the metal wire 1, the metal wire 1 is unwound from the bobbin 2 and used.

[0072] For example, the metal mesh 10 can be manufactured by weaving the metal wire 1 as at least one of the weft and warp threads. The metal mesh 10 is an example of a tungsten product including the metal wire 1, for example, a screen mesh used in screen printing. In this way, the metal wire 1 is used as a wire material for the screen mesh. The metal mesh 10 may be used not only for the screen mesh, but also for clothing such as gloves, socks, and jackets.

[0073] Since an oxide film is not easily formed on the surface of the metal wire 1, it is possible to prevent the wire from becoming bent or breaking when it is taken out of the bobbin 2 and when it is woven. Also, when it is used as a screen mesh, it is possible to prevent the wire from breaking.

[0074] The metal wire 1 may also be used as saw wire, medical device components (e.g., catheters), stranded wires, or ropes. Alternatively, the metal wire 1 may be used as wires or filaments for electric discharge machining. The metal wire 1 may be used as a single wire, or a plurality of metal wires 1 may be twisted or bundled together for use. It can be used in various tungsten products that take advantage of the characteristics of tungsten, such as its high melting point and high hardness.

[0075] 6 is a schematic diagram showing a coiling process of a filament coil using the metal wire 1 according to the present embodiment. The filament coil is formed, for example, by covering a core wire made of a tungsten wire 21 and a molybdenum wire 22 with the metal wire 1. For example, the metal wire 1, which is a tungsten wire with a wire diameter of 20 μm, is unwound at a rotation speed of 20,000 rpm. By rotating the core wire at high speed by an axial motor, the metal wire 1 is unwound by centrifugal force and wound around the outer peripheral surface of the core wire. By moving the core wire in the axial direction at a constant speed, the metal wire 1 is wound around the outer peripheral surface of the core wire at equal intervals.

[0076] During this unwinding, if the tungsten surface is oxidized, adhesion occurs and the wire becomes bent or breaks. According to the metal wire 1 of the present embodiment, as described above, the oxidation of the surface is suppressed, so that the occurrence of the wire becoming bent and breaks can be suppressed.

[0077] 7 is a perspective view showing a rewinding device 30 for a metal wire 1 according to the present embodiment. The rewinding device 30 rewinds the metal wire 1 wound around a bobbin 2 onto a bobbin 3. The rewinding device 30 may be an electrodeposition device that performs not only rewinding but also electrodeposition. That is, the metal wire 1 unwound from the bobbin 2 may be subjected to electrodeposition processing and then wound onto the bobbin 3. The electrodeposition processing is performed, for example, in order to attach abrasive grains to the surface when the metal wire 1 is used as a saw wire.

[0078] For example, when the metal wire 1 is a tungsten wire for saw wire, the metal wire 1 having a wire diameter of 40 μm is unwound from the bobbin 2 at a maximum wire speed of 800 m / min during rewinding or electrodeposition. If the tungsten surface is oxidized during unwinding, adhesion occurs, and the wire becomes bent or breaks. In addition, when the wire becomes bent, the work roller of the saw wire is likely to jump to the adjacent wire position. In contrast, according to the metal wire 1 according to the present embodiment, as described above, the oxidation of the surface is suppressed, so that the occurrence of the wire bent and breaks can be suppressed. The occurrence of the wire position jump during use as a saw wire can also be suppressed.

[0079] [Effects, etc.] As described above, the metal wire according to the present embodiment is a tungsten wire or a tungsten alloy wire, and the amount of alkali metal present on the surface of the metal wire is 2.0 μg or less per 1 g of the metal wire.

[0080] This can prevent the wire from becoming bent or breaking.

[0081] Also, for example, the amount of alkali metal present on the surface of the metal wire is 1.0 μg or less per 1 g of the metal wire.

[0082] This can further prevent the wire from becoming bent and breaking.

[0083] Also, for example, the amount of alkali metal present on the surface of the metal wire is 0.5 μg or less per 1 g of the metal wire.

[0084] This can further prevent the wire from becoming bent or breaking.

[0085] For example, the wire diameter of the metal wire is 40 μm or less. For example, the wire diameter of the metal wire may be 13 μm or less.

[0086] In this way, the smaller the wire diameter of the tungsten wire, the more likely it is that the wire will become bent or broken when the surfaces are stuck together, so the advantage of the surface being less likely to oxidize and sticking being suppressed can be more effectively utilized. Note that ultra-fine tungsten wires with a wire diameter of 40 μm or less have high tensile strength and can be used for a variety of purposes.

[0087] Also, for example, the metal wire may be used as a wire material for a saw wire.

[0088] This makes it difficult for the wire to become bent or broken when unwound during electrodeposition of abrasive grains, allowing the electrodeposition to be performed uniformly on the surface of the metal wire. Also, it is possible to suppress jumps in the wire position when used as a saw wire.

[0089] Also, for example, metal wires may be used as wire materials for a screen mesh.

[0090] This makes it difficult for the wire to become bent or broken both during weaving and during use, making it more resistant to pressure from a squeegee or the like and enabling increased accuracy in screen printing.

[0091] (others) Although the metal wire according to the present invention has been described based on the above embodiment, the present invention is not limited to the above embodiment.

[0092] For example, in the above embodiment, the metal wire is assumed to be wound around a bobbin and stored, but this is not limiting. A plurality of metal wires may be bundled and stored. Alternatively, the metal wire may be stored in an environment where it may adhere to other metal wires or other objects. Even if the wire is not stored for a long period of time, the generation of an oxide film during use, for example, when the wire is used in an environment where it may come into contact with moisture, can be suppressed, and therefore, breakage during use and the occurrence of bends in the wire can be suppressed.

[0093] In addition, the present invention also includes forms obtained by applying various modifications to each embodiment that a person skilled in the art may think of, and forms realized by arbitrarily combining the components and functions of each embodiment within the scope that does not deviate from the spirit of the present invention. [Explanation of symbols]

[0094] 1 Metal Wire 10 Metal Mesh

Claims

1. A metal wire which is a tungsten wire or a tungsten alloy wire, the amount of alkali metal present on the surface of the metal wire is greater than 0.0 μg and less than 2.0 μg per 1 g of the metal wire; The wire diameter of the metal wire is 40 μm or less. Metal wire.

2. The amount of alkali metal present on the surface of the metal wire is 1.0 μg or less per 1 g of the metal wire. The metal wire of claim 1 .

3. The amount of alkali metal present on the surface of the metal wire is 0.5 μg or less per 1 g of the metal wire.

3. The metal wire according to claim 1 or 2.

4. The wire diameter of the metal wire is 13 μm or less. The metal wire according to any one of claims 1 to 3.

5. The content of tungsten in the metal wire is 90 wt % or more. The metal wire according to any one of claims 1 to 4.

6. A metal wire which is a tungsten wire or a tungsten alloy wire, the amount of alkali metal present on the surface of the metal wire is greater than 0.0 μg and not greater than 2.0 μg per 1 g of the metal wire; The wire diameter of the metal wire is 40 μm or less. Saw wire.

7. A metal wire which is a tungsten wire or a tungsten alloy wire, the amount of alkali metal present on the surface of the metal wire is greater than 0.0 μg and less than 2.0 μg per 1 g of the metal wire; The wire diameter of the metal wire is 40 μm or less. Metal mesh.

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