Patent Application
20240321480
The present application is based on Japanese patent application No. 2023-045018 filed on Mar. 22, 2023, the entire contents of which are incorporated herein by reference.
The present invention relates to an insulated electric wire that is configured by covering the outer periphery of a metal conductor with an insulation coating layer and a manufacturing method of the insulated electric wire.
Conventionally, some of the enameled wires that are configured by forming an enamel layer on a conductor wire have improved self-lubricating properties. The applicant of the present invention proposes enameled wires that are described in Patent Literatures 1 and 2 as self-lubricating enameled wires.
The self-lubricating enameled wire that is described in Patent Literature 1 has a lubricant layer that is made by mixing wax and silane coupling agent into a polyamide resin as an outer layer of an enamel coating layer formed onto a conductor wire. The self-lubricating enameled wire that is described in Patent Literature 2 has a polyamide-imide resin varnish that is coated and baked so that it has a thickness of 3 to 4 μm as an outer layer of a polyester imide enamel coating layer formed onto a conductor wire.
Some application uses of enameled wires may require improved slipperiness, e.g., in the case where a plurality of enameled wires is arranged inside a fine tube and repeatedly bent. Also, when forming an outermost layer with high solid lubrication on an enameled wire to improve slipperiness, it is necessary that the layers have high adhesion strength so that the outermost layer is not easily peeled off. Also, the “slipperiness” here means a quality that a wire slips easily against other objects when the wire contacts it.
The object of the present invention is to provide an insulated electric wire with high slipperiness and a highly strong insulation coating layer and its manufacturing method.
To solve the above-mentioned problem, one aspect of the present invention provides an insulated electric wire, comprising:
Further, another aspect of the present invention provides a manufacturing method of the insulated electric wire according to the aspect of the present invention, comprising: forming the lubricant layer by adhering a dispersion liquid, including the fluorine-based fine particles dispersed into a liquid dispersion medium, onto an outer periphery of the enamel insulation layer, and drying and baking the dispersion liquid.
According to the present invention, it is possible to provide an insulated electric wire having high slipperiness and a highly strong insulation coating layer, and its manufacturing method.
The metal conductor 2 is composed of an alloy that includes at least one of the highly conductive metal elements, copper, silver, and aluminum, or composed of a single metal, either copper, silver, or aluminum. Additionally, a plated wire with tin or other metals plating on the surface of a core composed of the alloy or single metal mentioned above, e.g., or a clad wire wherein dissimilar metals are rolled and joined on the surface of the core may be used as the metal conductor 2. In the present embodiment, the metal conductor 2 has a circular cross-section, and an outer diameter D2 of the conductor is 10 μm or more and 50 μm or less.
The insulation coating layer 3 has a double-layer structure that is composed of an enamel insulation layer 31 and a lubricant layer 32. The enamel insulation layer 31 is formed on the metal conductor 2, and the lubricant layer 32 is formed directly on the enamel insulation layer 31. The lubricant layer 32 is an outermost layer of the insulation coating layer 3, and the enamel insulation layer 31 is an inner layer with respect to the lubricant layer 32. A thickness T3 of the entire insulation coating layer 3 is 3 μm or more and 10 μm or less. A thickness T31 of the enamel insulation layer 31 and a thickness T32 of the lubricant layer 32 are both 1 μm or more and 8 μm or less. Furthermore, each of these thicknesses T3, T31, and T32 is a mean thickness that is measured at multiple locations (e.g., four locations) on each layer. The thickness of each layer can be measured, e.g., by a SEM image (e.g. magnification 1000×) of a cross-section perpendicular to longitudinal direction of the insulated electric wire 1.
The lubricant layer 32 has fluorine-based fine particles as a lubricant, which decreases a coefficient of friction on an outer surface 1a of the insulated electric wire 1, enhancing the slipperiness of the insulated electric wire 1. In addition, the enamel insulation layer 31 includes fluorine-based fine particles of the same kind as in the lubricant layer 32. The main component of the lubricant layer 32 is fluorinated resin, and the content of fluorinated resin per volume is higher than that of the enamel insulation layer 31. Also, the lubricant layer 32 may be consisting of fluorinated resin.
The fluorine-based fine particles in the enamel insulation layer 31 and the lubricant layer 32 can be manufactured, e.g., by emulsion polymerization or pulverization method. An average particle size of the fluorine-based fine particles is, e.g., 1.0 μm or less. It is particularly preferable that an average particle size of the fluorine-based fine particles is 0.2 μm or more and 0.5 μm or less. An average particle size of the fluorine-based fine particles is a particle diameter at 50% integration in particle size distribution obtained by laser diffraction using a particle size distribution analyzer (MT3000II) of Microtrac Corporation. In addition, the fluorine-based fine particles may or may not be crosslinked.
As the fluorine-based fine particles for the enamel insulation layer 31 and the lubricant layer 32, fine particles of polytetrafluoroethylene (PTFE) or fine particles of perfluoroalkoxyalkane (PFA) may be used appropriately. When the fluorine-based fine particles of the lubricant layer 32 are the fine particles of polytetrafluoroethylene (PTFE), the enamel insulation layer 31 also includes the fine particles of polytetrafluoroethylene (PTFE). Also, when the fluorine-based fine particles of the lubricant layer 32 are fine particles of perfluoroalkoxyalkane (PFA), the enamel insulation layer 31 also includes fine particles of perfluoroalkoxyalkane (PFA).
With this configuration, the fluorine-based fine particles of the enamel insulation layer 31 and the fluorine-based fine particles of the lubricant layer 32 are tightly bonded, and the adhesion strength of the lubricant layer 32 to the enamel insulation layer 31 is enhanced. Also, peeling off the lubricant layer 32 from the enamel insulation layer 31 is deterred when the insulated electric wire 1 rubs against surrounding components.
The percentage of the fluorine-based fine particles in the enamel insulation layer 31 is 0.5 wt % or more and 60.0 wt % or less. This is because the effect of increasing the adhesion strength to the lubricant layer 32 may not be enough if the percentage is less than 0.5 wt %, and the fluorine-based fine particles of the enamel insulation layer 31 may easily fall off if the percentage exceeds 60.0 wt %. Moreover, from the viewpoint of preventing a decrease in withstand voltage and ensuring sufficient withstand voltage while improving the adhesive strength of the enamel insulation layer 31, it is preferable that the fluorine content in the enamel insulation layer 31 be 1.0 wt % or more and 20 wt % or less. Also, the percentage of the fluorine-based fine particles in the enamel insulation layer 31 can be measured, e.g., by Energy Dispersive X-ray Fluorescence Analyzer (EDX). The fluorine content detected by the EDX is, e.g., 0.5 wt % or more and 45.6 wt % or less.
The enamel insulation layer 31 has, e.g., a lot of fluorine-based fine particles 310 that are dispersed and mixed in a base part 311 composed of a base polymer material such as polyimide, and some of the fluorine-based fine particles 310 are exposed on an outer surface 31a of the enamel insulation layer 31. The fluorine-based fine particles 310 that are exposed on the outer surface 31a are partially buried inside the base part 311. The base part 311 is formed by baking varnish composed of imide resin.
The lubricant layer 32 is formed by the fluorine-based fine particles 320 combined with the fluorine-based fine particles 310 that are exposed on the outer surface 31a of the enamel insulation layer 31. The enamel insulation layer 31, intervening between the metal conductor 2 and the lubricant layer 32, functions as a primer to enhance the strength of the insulation coating layer 3.
The manufacturing device 4 has first to eighth guide rollers 411 to 418, first and second tanks 421 and 422, and first and second electric furnaces 431 and 432. The first tank 421 stores a mixed varnish 501 that is a liquid varnish mixed with the fluorine-based fine particles. The second guide roller 412 and the third guide roller 413 are placed inside the first tank 421.
The second tank 422 stores a dispersion liquid 502 that is a liquid dispersant (dispersion medium) in which the fluorine-based fine particles as dispersoid are dispersed. As a dispersant for the dispersion liquid 502, it is preferable to use a water-based product. The sixth guide roller 416 and the seventh guide roller 417 are placed inside the second tank 422.
The first guide roller 411 is positioned above the second guide roller 412, and the metal conductor 2 which is sent out from the feed reel 401 enters the first tank 421 by way of the first guide roller 411, and soaks in the mixed varnish 501. At that time, the mixed varnish 501 adheres to the outer periphery of the metal conductor 2. The fourth guide roller 414 is positioned above the third guide roller 413, and the first electric furnace 431 is placed between the third guide roller 413 and the fourth guide roller 414.
The fifth guide roller 415 is positioned above the sixth guide roller 416 and on the side of the fourth guide roller 414. The eighth guide roller 418 is positioned above the seventh guide roller 417, and the second electric furnace 432 is placed between the seventh guide roller 417 and the eighth guide roller 418.
The mixed varnish 501 adhered to the metal conductor 2 is heated and baked by the first electric furnace 431, and the enamel insulation layer 31 is formed. The baking temperature of the enamel insulation layer 31 is the temperature at which the base part 311 is crosslinked, and it is, e.g., 320° C. Hereinafter, the metal conductor 2 on which the enamel insulation layer 31 has been formed is called an enameled metal conductor wire 10.
The enameled metal conductor wire 10 goes toward the second tank 422 guided by the fourth guide roller 414 and the fifth guide roller 415, and soaks into the dispersion liquid 502 guided by the sixth guide roller 416 and the seventh guide roller 417. The dispersion liquid 502 adhering onto the enameled metal conductor wire 10, is dried and baked by the second electric furnace 432. At that time, the fluorine-based fine particles that are exposed on the surface of the enamel insulation layer 31 are fusion-bonded with the fluorine-based fine particles of the dispersion liquid 502, and the lubricant layer 32 is formed. The baking temperature of the lubricant layer 32 is higher than that for the enamel insulation layer 31 at the first electric furnace 431, e.g., 480° C. The insulated electric wire 1 on which the lubricant layer 32 has been formed, is guided by the eighth guide roller 418 and is reeled in by the take-up reel 402.
As described above, the manufacturing method of the insulated electric wire 1 has an enamel insulation layer forming step where the mixed varnish 501 is adhered onto the metal conductor 2 and baked to form the enamel insulation layer 31, and a lubricant layer forming step where the dispersion liquid 502 is adhered onto the outer periphery of the enamel insulation layer 31, dried, and baked, to form the lubricant layer 32. In addition, in case where the enamel insulation layer 31 is not thick enough after performing the enamel insulation layer forming step one time, the enamel insulation layer forming step may be performed multiple times to manufacture the enameled metal conductor wire 10. Also, in the case where the lubricant layer 32 is not thick enough after performing the lubricant layer forming step one time, the lubricant layer forming step may be performed multiple times to manufacture the insulated electric wire 1.
When forming the lubricant layer 32 in the same manner described above on the enamel insulation layer 31, which has been formed in this way, and rubbed lightly with a finger, the lubricant layer 32 was confirmed to be more difficult to peel off.
It is preferable that the catheter tube 100 have a fine diameter to improve the minimal invasiveness and reduce the burden on an examinee. Furthermore, the catheter tube 100 is bent at multiple points while it is inserted into a human body. Therefore, it is important that the insulation coating layer 3 is not worn out due to friction, etc., when the insulated electric wires 1 are rubbed against one another inside the catheter tube 100.
The catheter tube 100 using the insulated electric wire 1, according to the present embodiment, is able to respond to such a request. Also, the insulated electric wire 1 has, e.g., the enamel insulation layer 31 as an inner layer. Therefore, even if a part of the lubricant layer 32 is peeled off due to long-time use, a short-circuit among the insulated electric wires 1 can be prevented.
In addition, in order to improve the workability of terminal processing of the catheter tube 100, it is preferable to do color coding of the plurality of the insulated electric wires 1. The color coding can be realized by adding a pigment to at least one of the enamel insulation layer 31 and the lubricant layer 32. As the pigment, it is preferable to use an inorganic pigment rather than an organic pigment to avoid deterioration by the effect of heat from sintering the lubricant layer 32. Because the lubricant layer 32 is translucent, even when only the enamel insulation layer 31 includes an inorganic pigment, the color of the enamel insulation layer 31 can be recognized from outside the lubricant layer 32 while working. Furthermore, by adding an inorganic pigment to the enamel insulation layer 31 only, the insulated electric wire 1 can be color-coded while maintaining the slipperiness of the lubricant layer 32. As the inorganic pigment, e.g., titanium oxide, iron oxide, zinc oxide may be used appropriately.
According to the first embodiment described above, high slipperiness can be obtained because the outermost layer, that is, the lubricant layer 32 has the fluorine-based fine particles as a lubricant. Also, as explained with reference to
In general, for an extremely fine metal conductor wire with a conductor diameter of 50 μm or less, e.g., it is difficult to melt-extrude a fluororesin of polytetrafluoroethylene (PTFE) or the like on the outer periphery. Also, if the fluororesin is melt-extruded on the outer periphery of an extremely fine metal conductor wire like the above after a thick enamel layer is formed on the outer periphery, its wire diameter becomes thick. According to the present embodiment, the formation of the insulation coating layer 3 by joining the enamel insulation layer 31 and the lubricant layer 32 enables the insulated electric wire 1 to have a small diameter and high solid lubricity, and the insulation coating layer 3 with high strength.
When the fluorine-based fine particles included in the enamel insulation layer 31 are fine particles of polytetrafluoroethylene (PTFE), using the fine particles of polytetrafluoroethylene (PTFE) as the fluorine-based fine particles of the lubricant layer 32 as well can enhance the adhesion of the lubricant layer 32. The lubricant layer 32 may contain a small amount of fine particles of perfluoroalkoxyalkane (PFA) (a smaller amount of the fine particles of polytetrafluoroethylene (PTFE)).
Because perfluoroalkoxyalkane (PFA) is highly heat fusible, the lubricant layer 32 containing the fine particles of perfluoroalkoxyalkane (PFA) makes the fine particles of polytetrafluoroethylene (PTFE) of the lubricant layer 32 tightly bound to one another. Therefore, it is able to prevent the lubricant layer 32 from partially peeling off, e.g., due to friction and becoming thinner, and to prevent microscopic pinholes from being created on the lubricant layer 32.
It is preferable that the percentage of the fine particles of perfluoroalkoxyalkane (PFA) in the lubricant layer 32 be, in concrete terms, 0.5 wt % or more and 5.0 wt % or less. This is because advantageous effects may not be obtained if the percentage of fine particles of perfluoroalkoxyalkane (PFA) is 0.5 wt % or less. The upper limit value for the percentage of the fine particles of perfluoroalkoxyalkane (PFA) in the lubricant layer 32 has no specific limits, but it may be, e.g., 5.0 wt % or less.
According to the modified example, the strength of the insulation coating layer 3 can be further improved, while the high slipperiness is maintained. Also, the lubricant layer 32 like this can be formed by mixing the fine particles of perfluoroalkoxyalkane (PFA) in addition to the fine particles polytetrafluoroethylene (PTFE) into the dispersion liquid 502 that is used in the lubricant layer forming step as dispersoid.
As the insulative wire 20, e.g., resin fibers that can withstand fluororesin sintering temperatures such as polyester synthetic fiber, or polyamide synthetic fiber including nylon yarn can be used. The metal conductor 2 is formed by plating on the insulative wire 20. In this case, a plating thickness T20 is, e.g., 0.2 μm or more and 5.0 μm or less. If the plating thickness T20 is less than 0.2 μm, sufficient conductivity is not ensured, and the plating layer strength is small and easily cracked, which may cause poor conduction. Also, it is difficult to form a plating with the plating thickness T20 larger than 5.0 μm, and moreover, the plating layer with the plating thickness larger than 5.0 μm is hard and easily cracked, which may cause poor conduction.
According to the second embodiment, the insulated electric wire 1A having high slipperiness and the insulation coating layer 3 with high strength can be obtained as in the first embodiment. Furthermore, the manufacturing cost can be reduced compared with a case where the metal conductor 2 having the outer diameter D2 of 50 μm or less is formed by wire drawing.
Next, technical ideas understood from the above embodiments are described with reference to the reference numerals and the like used in the embodiments. However, each reference numeral in the following description does not limit the constituent elements in the scope of claims to the members and the like specifically shown in the embodiments.
According to the first feature, an insulated electric wire 1, 1A includes a metal conductor 2; and an insulation coating layer 3 covering an outer periphery of the metal conductor 2, wherein the insulation coating layer 3 includes a lubricant layer 32 including fluorine-based fine particles 320 as a lubricant as an outermost layer, and an enamel insulation layer 31 including fluorine-based fine particles 310 as an inner layer with respect to the lubricant layer 32.
According to the second feature, in the insulated electric wire 1, 1A, as described by the first feature, the fluorine-based fine particles 320 of the lubricant layer 32 and the fluorine-based fine particles 310 of the enamel insulation layer 31 are of a same kind.
According to the third feature, in the insulated electric wire 1, 1A, as described by the second feature, the fluorine-based fine particles 320 of the lubricant layer 32 and the fluorine-based fine particles 310 of the enamel insulation layer 31 are fine particles of polytetrafluoroethylene or fine particles of perfluoroalkoxyalkane.
According to the fourth feature, in the insulated electric wire 1, 1A, as described by the third feature, a percentage of the fluorine-based fine particles 310 in the enamel insulation layer 31 is 0.5 wt % or more and 60.0 wt % or less.
According to the fifth feature, in the insulated electric wire 1, 1A, as described by any one of the first to third features, the fluorine-based fine particles 310 of the enamel insulation layer 31 are the fine particles of polytetrafluoroethylene, and the lubricant layer 32 includes the fine particles of perfluoroalkoxyalkane in addition to the fine particles of polytetrafluoroethylene as the fluorine-based fine particles 320.
According to the sixth feature, in the insulated electric wire 1, 1A, as described by the fifth feature, a percentage of the fine particles 320 of perfluoroalkoxyalkane in the lubricant layer 32 is 0.5 wt % or more and 5.0 wt % or less.
According to the seventh feature, in the insulated electric wire 1, 1A, as described by the first feature, an outer diameter D2 of the metal conductor 2 is 10 μm or more and 50 μm or less, a thickness T3 of the insulation coating layer 3 is 3 μm or more and 10 μm or less, a thickness T32 of the lubricant layer 32 is 1 μm or more and 8 μm or less, and a thickness T31 of the enamel insulation layer 31 is 1 μm or more and 8 μm or less.
According to the eighth feature, the insulated electric wire 1, 1A, as described by first feature, further includes an insulative wire 20 in a thread-like form, wherein an outer periphery of the insulative wire 20 is coated with the metal conductor 2.
According to the ninth feature, in the insulated electric wire 1, 1A, as described by the first or eighth feature, the metal conductor 2 is composed of an alloy including at least one of copper, silver, and aluminum, or composed of a single metal.
According to the tenth feature, in the insulated electric wire 1, 1A, as described by the first or eighth feature, the metal conductor 2 composed of an alloy including at least one of copper, silver, and aluminum, or composed of a single metal is plated on a surface.
According to the eleventh feature, a manufacturing method of the insulated electric wire 1, 1A as described by the first feature, includes forming the lubricant layer 32 by adhering a dispersion liquid 502, including the fluorine-based fine particles 320 dispersed into a liquid dispersion medium, onto an outer periphery of the enamel insulation layer 31, and drying and baking the dispersion liquid 502.
That is all for the description of the first and second embodiments and the variant of the present invention, but the description does not limit the invention according to the scope of claims. Additionally, it should be noted that not all combinations of features described in the first and second embodiments and the variant are essential to the means for solving problems of the invention. For example, in the first embodiment, a case where a plurality of insulated electric wires 1 are used for the catheter tube 100, but a usage of the insulated electric wire 1 and the insulated electric wire 1A is not limited to this.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-045018 | Mar 2023 | JP | national |
