JP2016157607A - Insulated wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulated wire having an insulation coating with high abrasion resistance and adhesion while formed with a resin composition including a polyphenylene sulfide resin as a primary component, the insulated wire being highly resistant to heat.SOLUTION: An insulated wire 100 includes a conductor 101 and an insulator 102 formed in a periphery of the conductor 101. The insulator 102 includes a polyphenylene sulfide resin as a primary component. The insulated wire further includes an insulation coating 103 formed with a resin composition having a tensile strength of 70 MPa or less when a degree of crystallinity is 85% or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an insulated wire suitable mainly for winding applications for industrial motors.

  In recent years, industrial motors represented by drive motors such as electric vehicles and hybrid vehicles are not only reduced in size and weight but also driven by inverters for higher drive voltage and higher power performance for higher output. The development is progressing rapidly.

  However, due to the superposition of the high drive voltage and inverter surge voltage associated with the drive voltage increase and inverter drive of industrial motors, the risk of partial discharge occurring in the insulated wires that make up the windings of industrial motors increases. ing.

  In particular, in an insulated wire having a low partial discharge inception voltage (PDIV), partial discharge occurs even at a low voltage, and the insulation coating that ensures the insulation performance of the insulated wire is gradually eroded by the partial discharge. There is a concern that it will eventually result in poor insulation.

  This partial discharge start voltage can be increased by lowering the relative dielectric constant of the insulating film than before or by increasing the film thickness of the insulating film.

  In order to increase the partial discharge starting voltage by lowering the relative dielectric constant of the insulating film than before, the relative dielectric constant of a fluorine-containing polymer (for example, polyimide resin (PI) or polyamideimide resin (PAI)) is conventionally increased. It is conceivable to use insulation coatings made of lower materials, but these materials are expensive and lead to higher prices for industrial motors, so use insulation coatings made of these materials It is difficult.

  On the other hand, when increasing the partial discharge start voltage by increasing the film thickness of the insulating film, the film thickness of the insulating film is changed from 100 μm to 200 μm so that it can withstand the high drive voltage of an industrial motor and inverter drive. It is necessary to make it as thick as possible.

  However, in the normal enamel coating method, since the film thickness of the insulating film that can be formed by one coating is about several μm, in order to increase the film thickness of the insulating film from about 100 μm to about 200 μm, It is necessary to increase the number of times of coating significantly compared to the conventional method, and the price of industrial motors increases due to the increase in the number of times of coating. Therefore, it is not practical to form an insulating film by the usual enamel coating method. There is also a problem that the risk of occurrence of defects such as the formation of granular defects in the insulating coating increases due to the increase in the thickness.

  Considering this point, it has been studied to make the insulating film thicker than before by melt-extrusion coating a thermoplastic resin around the conductor to form the insulating film.

  Here, as the thermoplastic resin, a resin such as polyphenylene sulfide resin (PPS), polyether sulfone resin (PES), polyetherimide resin (PEI), or polyether ether ketone resin (PEEK) may be used. Of these resins, polyphenylene sulfide has the characteristics required for insulating coatings such as chemical resistance, rigidity, and electrical insulation, and is cheaper than other engineering plastics. Resin is promising.

  Polyphenylene sulfide resin is a crystalline polymer, and it is known that chemical resistance and heat resistance are improved by crystallization. Therefore, polyphenylene sulfide resin is molded into a desired shape (for example, injection molding or extrusion molding). When the polyphenylene sulfide resin is not crystallized later, the polyphenylene sulfide resin is usually heated to a temperature equal to or higher than the crystallization temperature to increase the crystallinity of the polyphenylene sulfide resin to produce a product.

  In industrial motor winding applications, it is necessary to bend or stretch the insulated wire to deform the insulated wire, and the insulated wire has an insulation coating formed by melt extrusion coating of polyphenylene sulfide resin. Since the lower the crystallinity of the insulation film made of polyphenylene sulfide resin, the better the mechanical properties such as bending and elongation properties of the insulation film when deforming the insulated wire, the crystallization of the insulation film In general, the insulated wire is deformed in a low degree.

  After the deformation process, the chemical resistance and heat resistance are improved by heating the insulating film to a temperature higher than the crystallization temperature to increase the crystallinity of the insulating film.

  For example, Patent Document 1 assembles an armature of a rotating electric machine that involves deformation processing of an insulating wire in a state where the polyphenylene sulfide resin composition of the extrusion-coated resin layer formed on the outer periphery of the conductor is not crystallized. It is described that the insulated wire after completion is crystallized by heating the insulated wire to a temperature of 120 ° C. or higher.

JP 2010-055964 A

  By the way, there is a possibility that the insulating coating peels off from the conductor due to deformation processing when the insulated wire is processed into a winding, and the insulating coating may be lifted or torn, and in order to prevent this, in Patent Document 1, The crystallinity of the extrusion-coated resin layer made of the polyphenylene sulfide resin composition before deformation is lowered to lower its hardness, and after assembly, the crystallinity of the extrusion-coated resin layer is increased to increase its hardness. It is described to do.

  When the crystallinity of the insulating film made of polyphenylene sulfide resin is low and its hardness is low (insulating film is soft), the toughness of the insulating film is high, so the stress applied to the insulating film during deformation processing can be reduced, In subsequent assembly of the armature of a rotating electrical machine, the insulating coating is worn (for example, scratched or indented) by pressing or rubbing against a molding jig or the like when inserting an insulated wire into a core slot or molding a coil end. Is likely to occur, and there is a possibility that the insulating coating is reduced by wear and leads to insulation failure.

  In order to prevent such abrasion of the insulating film, if the crystallinity of the insulating film is increased and its hardness is increased before deformation processing, the adhesion of the insulating film is lowered, and as described above, the insulating film is insulated. The film tends to float or break.

  Accordingly, an object of the present invention is to provide an insulated wire having an insulating film having high wear resistance and high adhesion while being formed of a resin composition containing a polyphenylene sulfide resin as a main component, and having high heat resistance. There is.

  The present invention created to achieve this object includes a conductor and an insulator formed around the conductor, and the insulator contains polyphenylene sulfide resin as a main component and is crystallized. An insulated wire having an insulating coating formed of a resin composition having a tensile strength of 70 MPa or less when the degree is 85% or more.

  The resin composition preferably contains a silicone rubber or a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin as an auxiliary component.

  The resin composition preferably includes a main component of 80% by mass or more and 90% by mass or less and a subcomponent of 20% by mass or less and 10% by mass or more.

  The insulating coating is preferably formed directly or indirectly around the conductor.

  According to the present invention, it is possible to provide an insulated wire which has an insulating film having high wear resistance and adhesion while being formed of a resin composition containing a polyphenylene sulfide resin as a main component, and which has high heat resistance. it can.

It is a perspective view which shows the insulated wire which concerns on this invention.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings.

  As shown in FIG. 1, an insulated wire 100 according to a preferred embodiment of the present invention includes a conductor 101 and an insulator 102 formed around the conductor 101.

  The conductor 101 is made of a highly conductive metal such as copper (eg, low oxygen copper or oxygen-free copper) or aluminum, and has a rectangular wire having a rectangular cross section, a round wire having a circular cross section, or a circular cross section. It consists of a stranded wire formed by twisting a plurality of round wires or the like.

  The insulator 102 has an insulating coating 103 formed of a resin composition containing a polyphenylene sulfide resin as a main component and having a tensile strength of 70 MPa or less when the crystallinity is 85% or more. 103 is formed directly or indirectly around the conductor 101.

  Here, the degree of crystallinity [%] means the degree of crystallinity before the insulated wire 100 is deformed, and the heat of cold crystallization (exothermic enthalpy) by differential scanning calorimetry (DSC). When [J / g] is Hc and the heat of fusion (endothermic enthalpy) by differential scanning calorimetry [J / g] is Hm, it is expressed by Equation (1).

  The heat of cold crystallization is the heat of crystallization during cold crystallization as measured by differential scanning calorimetry while raising the temperature of the resin composition from room temperature (40 ° C.).

  The reason for setting the crystallinity of the insulating coating 103 to 85% or more is that when the crystallinity of the insulating coating 103 is less than 85%, the wear resistance of the insulating coating 103 is lowered, so This is because when the assembly is performed, the insulating coating 103 is worn, the thickness of the insulating coating 103 is reduced, and desired electrical insulation characteristics cannot be obtained.

  In order to improve the wear resistance of the insulating coating 103 to the extent that the insulating coating 103 is not worn when the armature of the rotating electrical machine is assembled, the crystallinity of the insulating coating 103 is set to 90% or more. It is desirable.

  In order to set the crystallinity of the insulating coating 103 to 85% or more, the insulating coating 103 is preferably heated to a temperature equal to or higher than the cold crystallization temperature of the resin composition.

  Specifically, by heating the insulating film 103 to 120 ° C. or higher and 200 ° C. or lower which is a cold crystallization temperature, the crystallinity of the insulating film 103 can be set to 85% or higher.

  At this time, even if the insulating coating 103 is heated to 200 ° C. or more, the crystallinity of the insulating coating 103 can be 85% or more, but the elastic modulus of the insulating coating 103 is lowered during the heating and the insulating coating 103 is deformed. Therefore, it is desirable to increase the crystallinity of the insulating coating 103 by heating the insulating coating 103 to 200 ° C. or lower.

  The heating of the insulating coating 103 may be performed after the insulated wire 100 is manufactured or during the manufacturing of the insulated wire 100.

  Normally, when the crystallinity of the insulating coating 103 is 85% or more, the insulating coating 103 is less likely to be worn due to the increased hardness, but the crystallinity of the insulating coating 103 is 85%. Compared to the case of less than the above, mechanical properties such as bending characteristics and elongation characteristics of the insulating coating 103 when the insulating wire 100 is deformed are lowered, and the adhesiveness of the insulating coating 103 is reduced. When the deformation process is performed on the insulating film 103, there is a high possibility that the insulating film 103 will float or break.

  Accordingly, the present inventors have made extensive studies on the insulated wire 100 having the insulating coating 103 formed by melt extrusion coating a resin composition containing a polyphenylene sulfide resin as a main component. By making the tensile strength of the resin composition when the crystallinity of the resin composition constituting 103 is 85% or more within a predetermined range, the mechanical properties and adhesion of the insulating coating 103 are improved and the insulated wire It has been found that the workability of 100 can be improved.

  That is, the present inventors have found that the insulating coating 103 formed of a resin composition containing a polyphenylene sulfide resin as a main component and having a crystallinity of 85% or more and a tensile strength of 70 MPa or less has mechanical properties. It has been found that by adopting the insulating coating 103, the wear resistance and adhesion of the insulating coating 103 can be secured and the workability of the insulated wire 100 can be improved. It was.

  Here, the adhesion of the insulating coating 103 is determined by the rapid extension test, in which the insulated wire 100 is suddenly extended to break the conductor 101 and the insulating coating 103 and the length of the floating of the insulating coating 103 at the end of the breaking position. The exposed length of the conductor 101 is investigated and evaluated based on these lengths.

  Specifically, it is evaluated that the adhesiveness of the insulating coating 103 is higher as the floating length of the insulating coating 103 and the exposed length of the conductor 101 at the end of the fracture position are shorter. That is, in the rapid extension test, the followability of the insulating coating 103 to the deformation of the conductor 101 when the insulated wire 100 is deformed (for example, bent or stretched) is evaluated.

  During the rapid extension test or deformation process, the conductor 101 and the insulating coating 103 are stretched together, but the insulating coating 103 is stretched through a shearing force acting on the interface with the closely contacting conductor 101.

  Therefore, in order to stretch the insulating coating 103, the shear bonding strength between the conductor 101 and the insulating coating 103 is necessary. However, if the shear bonding strength is large, the insulating coating 103 can be obtained by a rapid stretching test or deformation process. Adhesion of can be rejected.

  That is, in order for the insulating coating 103 to follow the extension of the conductor 101, it is necessary for deformation processing by lowering the tensile strength of the insulating coating 103 in addition to the shear bonding strength between the conductor 101 and the insulating coating 103. It is necessary to ensure proper adhesion.

  When the tensile strength of the insulating coating 103 is more than 70 MPa, a force exceeding the shear bond strength acts between the conductor 101 and the insulating coating 103 when the insulating coating 103 is stretched in the rapid extension test. From this, the floating length of the insulating coating 103 and the exposed length of the conductor 101 become longer.

  On the other hand, when the tensile strength of the insulating coating 103 is 70 MPa or less, a force exceeding the shear adhesive strength acts between the conductor 101 and the insulating coating 103 when the insulating coating 103 is stretched in the rapid extension test. There is almost no breakage, and the floating length of the insulating coating 103 and the exposed length of the conductor 101 are shortened by the breakage caused by the rapid extension test.

  For the above reasons, the insulated wire 100 according to the present embodiment is formed of a resin composition that includes polyphenylene sulfide resin as a main component and has a tensile strength of 70 MPa or less when the crystallinity is 85% or more. An insulating coating 103 is employed.

  In addition, the polyphenylene sulfide resin refers to a resin having a structure having a repeating unit represented by the chemical formula (1) in principle, but in addition to this structure, unless the flexibility and heat resistance of the resin are greatly impaired, A sulfoxide group or an ether group may be included, and a substituent may be included in the benzene ring. Furthermore, the molecular chain may contain a branched structure or a crosslinked structure via a thioether group or an ether group.

  Moreover, in order to improve the elongation characteristic when the degree of crystallinity is 85% or more, the resin composition may contain silicone rubber, fluororesin, thermoplastic resin, or the like as a subcomponent.

  Examples of the silicone rubber include silicone rubber having an epoxy group, a carboxylic group, an alkyl group, or a phenyl group, and fine particles thereof.

  Examples of the fluororesin include polytetrafluoroethylene resin (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA), tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP), and polychlorotriethylene. Examples include fluoroethylene resin (PCTFE), ethylene-tetrafluoroethylene copolymer resin (ETFE), ethylene-chlorotrifluoroethylene copolymer resin (ECTFE), or polyvinylidene fluoride resin (PVDF).

  As the thermoplastic resin, phenoxy resin, polyamide resin (PA), polyethylene terephthalate resin (PET), polycarbonate resin (PC), polyethersulfone resin, polyetherimide resin, polyamideimide resin, polysulfone resin (PSU), or Polyphenylsulfone resin (PPSU) is exemplified, and an elastomer-modified material, a silicone-modified material, or the like can be used in combination in order to lower the tensile strength.

  It is desirable that the mixing ratio of the subcomponent in the resin composition is adjusted within a range in which various properties such as flexibility and chemical resistance required for an insulated wire as well as adhesion can be achieved. Specifically, polyphenylene sulfide resin It is desirable that the amount be about 1% by mass to 40% by mass so as not to significantly impair the characteristics.

  For example, in the case of a resin composition containing silicone rubber or a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin as an auxiliary component, the main component is 80% by mass or more and 90% by mass or less and 20% by mass or less and 10% by mass or more. It preferably contains an auxiliary component.

  Furthermore, a compatibilizer may be used when mixing the main component and the subcomponent, and examples of the compatibilizer include an epoxy group, a hydroxyl group, a carboxylic acid, an acid anhydride, an isocyanate group, a thiol group, or Examples thereof include compounds containing a sulfide group.

  In addition, when another insulating layer is interposed between the conductor 101 and the insulating coating 103, in addition to the conventionally used enamel layer, polyimide resin, polyamideimide resin, polyesterimide resin (PEI), polyetherimide An insulating layer made of a resin, an epoxy resin (EP), an unsaturated carboxylic acid resin, a polyurethane resin (PU), a formal resin (FM), or the like can be used.

  In addition to these, an insulating layer made of subcomponents such as silicone rubber, fluororesin, or thermoplastic resin mixed with polyphenylene sulfide resin as a main component can also be used.

  In addition, the insulator 102 may have another insulating coating or a self-bonding layer formed of a material different from that of the insulating coating 103.

  When manufacturing a rotating electrical machine using the insulated wire 100 described so far, after assembling the armature of the rotating electrical machine while deforming the insulated wire 100, the insulated wire 100 is post-heated to 120 ° C. or higher. Thus, the residual stress of the insulated wire 100 is reduced, and the crystallinity of the insulating coating 103 made of polyphenylene sulfide resin is set to be larger than 85% and not larger than 100%.

  Thereby, the chemical resistance of the insulated wire 100 can be improved. Originally, the insulated wire 100 has high chemical resistance because it employs the insulating film 103 having a crystallinity of 85% or more, but by post-heating in order to reduce the residual stress generated in the deformation process, Furthermore, chemical resistance can be improved. At the same time, the chemical resistance can be improved by setting the crystallinity of the insulating coating 103 to be greater than 85% and not greater than 100%.

  In addition, by increasing the heating temperature of the insulated wire 100, the residual stress of the insulated wire 100 is reduced and the heating time required for the crystallinity of the insulating coating 103 to be greater than 85% and less than 100% is shortened. However, if the heating temperature of the insulated wire 100 is too high, there is a high possibility that the insulating coating 103 will be deformed due to the low elastic modulus of the polyphenylene sulfide resin.

  Therefore, the heating temperature of the insulated wire 100 is preferably 150 ° C. or higher and 200 ° C. or lower. Regarding the heating time, if the heating temperature of the insulated wire 100 is about 150 ° C., the heating time is about 10 minutes, and if the heating temperature of the insulated wire 100 is 200 ° C., it becomes about several minutes.

  Therefore, it is possible to manufacture the rotating electrical machine while maintaining reliability such as chemical resistance and heat resistance.

  As described above, the insulating coating 103 can be formed by directly melt-extrusion-coating polyphenylene sulfide resin around the conductor 101, but in order to improve the adhesion between the conductor 101 and the insulating coating 103. An adhesion treatment may be performed.

  As the adhesion treatment, it is considered that the surface of the conductor 101 is chemically or physically modified, or an adhesion layer for improving the adhesion between the conductor 101 and the insulating coating 103 is interposed.

  The adhesion layer is not limited, but includes polysulfone resin, polyphenylsulfone resin, polyethersulfone resin, polyamide resin, polyetherimide resin, polyamideimide resin, polyimide resin, epoxy resin, and epoxy-modified olefin copolymer. Examples thereof include polymer resins, maleic acid-modified olefin copolymer resins, and unsaturated carboxylic acid resins.

  As described above, according to the present invention, there is provided an insulated wire that has an insulating coating with high wear resistance and adhesion while being formed of a resin composition containing a polyphenylene sulfide resin as a main component, and also has high heat resistance. Can be provided.

  Next, specific examples of the present invention will be described.

[Example 1]
A rectangular copper wire having a conductor size of 1.5 mm × 3.0 mm is used, which includes 90% by mass of polyphenylene sulfide resin as a main component and 10% by mass of silicone rubber as an auxiliary component, and has a crystallinity of 100%. A resin composition having a tensile strength of 63 MPa at one time was melt-extruded and coated at about 300 ° C. directly on a flat copper wire to form an insulating film having a thickness of about 150 μm to produce an insulated wire.

[Example 2]
A rectangular copper wire having a conductor size of 1.5 mm × 3.0 mm is used, and contains 80% by mass of polyphenylene sulfide resin as a main component and 20% by mass of silicone rubber as an auxiliary component, and has a crystallinity of 100%. A resin composition having a tensile strength of 53 MPa at one time was melt extrusion coated at about 300 ° C. directly on a flat copper wire to form an insulating film having a thickness of about 150 μm to produce an insulated wire.

[Example 3]
A rectangular copper wire having a conductor size of 1.5 mm × 3.0 mm is used, and 80% by mass of polyphenylene sulfide resin as a main component and 20% by mass of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin as a minor component; And a resin composition having a tensile strength of 65 MPa when the degree of crystallinity is 100% is melt extrusion coated at about 300 ° C. directly on a flat copper wire to form an insulating film having a thickness of about 150 μm. The insulated wire was produced by forming.

[Example 4]
A resin composition using a rectangular copper wire having a conductor size of 1.5 mm × 3.0 mm, containing 100% by mass of polyphenylene sulfide resin as a main component, and having a tensile strength of 70 MPa when the crystallinity is 85% By subjecting the product to melt extrusion coating at about 300 ° C. immediately above a flat copper wire, an insulating film having a thickness of about 150 μm was formed to produce an insulated wire.

[Comparative Example 1]
A rectangular copper wire having a conductor size of 1.5 mm × 3.0 mm is used, which contains 95% by mass of polyphenylene sulfide resin as a main component and 5% by mass of an elastomer as a minor component and has a crystallinity of 100%. An insulating wire having a film thickness of about 150 μm was formed by melt extrusion coating a resin composition having a tensile strength of 43 MPa at about 300 ° C. immediately above a flat copper wire to produce an insulated wire.

[Comparative Example 2]
A rectangular copper wire having a conductor size of 1.5 mm × 3.0 mm is used, which includes 90% by mass of polyphenylene sulfide resin as a main component and 10% by mass of an elastomer as a secondary component and has a crystallinity of 100%. A resin composition having a tensile strength of 38 MPa was melt-extruded and coated at about 300 ° C. directly on a flat copper wire to form an insulating film having a thickness of about 150 μm to produce an insulated wire.

[Comparative Example 3]
A resin composition using a rectangular copper wire having a conductor size of 1.5 mm × 3.0 mm, containing 100% by mass of polyphenylene sulfide resin as a main component, and having a tensile strength of 85 MPa when the crystallinity is 100% By subjecting the product to melt extrusion coating at about 300 ° C. immediately above a flat copper wire, an insulating film having a thickness of about 150 μm was formed to produce an insulated wire.

[Comparative Example 4]
A resin composition using a rectangular copper wire having a conductor size of 1.5 mm × 3.0 mm, containing 100% by mass of polyphenylene sulfide resin as a main component, and having a tensile strength of 160 MPa when the crystallinity is 100% By subjecting the product to melt extrusion coating at about 300 ° C. immediately above a flat copper wire, an insulating film having a thickness of about 150 μm was formed to produce an insulated wire.

[Crystallinity of insulating film]
The crystallinity of the insulating coating can be changed depending on the annealing conditions of the insulated wire. For example, by changing the annealing temperature in the range of about 120 ° C. or higher and 220 ° C. or lower as the annealing conditions and changing the annealing time in the range of several minutes to several tens of minutes, it is possible to form insulating films having different crystallinity degrees. it can.

[Insulating film adhesion]
The adhesion of the insulation coating is such that the distance between the chucks for fixing the insulated wire is 25 cm and the tensile speed is about 1000 mm / min. After that, the total length of the floating length of the insulating coating and the exposed length of the conductor at both ends at the break position is investigated. In the case of “No”, the test was rejected.

[Results of rapid extension test]
The insulated wires obtained in Examples 1 to 4 and Comparative Examples 1 and 2 have high adhesion of the insulating coating and passed the rapid extension test, but the insulated wires obtained in Comparative Examples 3 to 4 are insulated. The adhesion of the film was low, and the rapid extension test was rejected.

[Heat resistance test]
Regarding the heat resistance of the insulating coating, the insulated wire was left in a thermostatic bath at 200 ° C. for 1000 hours, and then the surface of the insulating coating was observed with a microscope. At this time, the case where there was no crack in the insulating coating was determined as pass “◯”, and the case where there was a crack was determined as “fail”.

[Results of heat resistance test]
The insulated wires obtained in Examples 1 to 4 and Comparative Examples 3 to 4 have high heat resistance of the insulating coating, but the insulated wires obtained in Comparative Examples 1 to 2 have low heat resistance of the insulating coating. Met.

100 Insulated wire 101 Conductor 102 Insulator 103 Insulating coating

Claims (4)

Conductors,
An insulator formed around the conductor;
With
The insulator includes a polyphenylene sulfide resin as a main component and an insulating film formed of a resin composition having a tensile strength of 70 MPa or less when the crystallinity is 85% or more. Insulated wires.   The insulated wire according to claim 1, wherein the resin composition contains a silicone rubber or a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin as a subcomponent.   The insulated wire according to claim 2, wherein the resin composition includes a main component of 80% by mass or more and 90% by mass or less and a subcomponent of 20% by mass or less and 10% by mass or more.   The insulated wire according to any one of claims 1 to 3, wherein the insulating coating is formed directly or indirectly around the conductor.

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