JP2021009828A - Coated conductor and method for manufacturing the same - Google Patents

Abstract

To provide a coated conductor excellent in abrasion resistance.SOLUTION: In a coated conductor, a belt-like insulating coating material (3) is spirally around the outer periphery of a conductor wire (1) extending in one direction. The insulating coating material contains an insulating film. The insulating coating material may include an adhesive layer on at least one main surface of the insulating film. An angle φ formed by a molecular orientation axis of the insulating film and a longitudinal direction of the insulating coating material is 10° to 80°, and an angle ω formed by the molecular orientation axis of the insulating film and an extension direction of the conductor is 10° or less.SELECTED DRAWING: Figure 3

Description

The present invention relates to a coated conductor in which an insulating coating material is wound around a conducting wire, and a method for manufacturing the same.

A coated conductor in which an insulating coating material is wound around the surface of a conducting wire is used for electric wires, cables, and the like. The coated conductor is required to have durability characteristics such as heat resistance, electrical insulation, chemical resistance, flame retardancy, wear resistance, and cut-through resistance (cutting resistance).

Patent Document 1 describes that a multilayer film obtained by laminating a polyimide film and a fluororesin layer as an adhesive layer is used as a coating material to exhibit excellent cutting resistance at high temperatures. Patent Document 2 describes that a coating material obtained by laminating a polyimide film having a predetermined strain stress and a fluororesin layer is excellent in wear resistance.

Japanese Unexamined Patent Publication No. 10-10040 International Publication No. 2014/192733

Cables used for aerospace applications such as aircraft, rockets, and spacecraft are more durable (resistant) to friction during installation in the aircraft and friction due to vibration during flight than cables for general use. Abrasion resistance) is required. Further, there is a high demand for weight reduction of cables for aerospace applications, and it is required to improve wear resistance while reducing the thickness of the covering material to reduce the weight.

The coated conductor is formed by spirally winding a band-shaped insulating coating material around the outer circumference of a conducting wire extending in one direction. The insulating coating material includes an insulating film and may have an adhesive layer on one or both main surfaces of the insulating film. The adhesive layer preferably contains a fluororesin. The insulating film is preferably a polyimide film. The insulating film may have a standard thickness of 75 μm and a molecular orientation degree MOR_c of 1.3 or more.

Since the molecular orientation axis of the insulating film and the extending direction of the conducting wire are substantially parallel, the wear resistance of the coated conductor can be improved. The angle ω formed by the molecular orientation axis of the insulating film and the extending direction of the conducting wire is preferably 10 ° or less.

In order to make the molecular orientation axis of the insulating film substantially parallel to the extending direction of the conducting wire, it is preferable that the insulating film has a molecular orientation axis in a direction that is neither parallel nor orthogonal to the longitudinal direction of the insulating coating material. The angle φ formed by the molecular orientation axis of the insulating film and the longitudinal direction of the insulating coating material is preferably 10 ° to 80 °.

An insulating fill having a molecular orientation axis in a direction that is neither parallel nor orthogonal to the longitudinal direction of the insulating coating material can be obtained, for example, by slitting a diagonally stretched film to a predetermined width. A film having a molecular orientation axis in a direction parallel to or orthogonal to the transport direction may be slit in an oblique direction.

The coated conductor of the present invention is suitable for cables for aerospace applications because the molecular orientation axis of the insulating film and the extending direction of the conducting wire are substantially parallel to each other and excellent wear resistance even when the thickness of the insulating coating material is small. is there.

It is a perspective view of a coated conductor. It is a figure for demonstrating the relationship between the longitudinal direction of a strip-shaped covering material, and the molecular orientation axis. It is a schematic diagram which shows the state of winding a covering material around a conducting wire. It is a schematic diagram which shows the state of winding a covering material around a conducting wire.

[Construction of coated conductor]
FIG. 1 is a perspective view of a coated conductor in which a strip-shaped insulating coating material 3 having a width W is spirally wound around a conducting wire 1 having a diameter D. In the coated conductor of the present invention, the extending direction of the conducting wire 1 (the direction along the AA line) and the molecular orientation axis p of the insulating film as the core layer of the insulating coating material 3 are (omitted) parallel. It is one of the features.

The conductor 1 used for the coated conductor may be any material as long as it is a conductor, and usually a metal such as copper, aluminum, or stainless steel is used. The metal may be an alloy, and the surface may be plated with various materials. As the metal material of the conducting wire, copper is preferable from the viewpoint of conductivity, and aluminum or the like is also preferable from the viewpoint of weight reduction. The lead wire 1 may be a single wire or a twisted plurality of metal wires (strand wires). The diameter D of the lead wire 1 is about 0.2 to 10 mm.

The covering material 3 is a strip-shaped insulating tape extending in one direction. The width W of the covering material 3 may be appropriately set according to the diameter D of the conducting wire 1, the winding angle θ of the covering material, and the like. The width W is, for example, about 1 to 50 mm. The covering material 3 is insulating and contains an insulating film. The covering material 3 preferably has an insulating film as a core layer and has an adhesive layer on at least one surface of the insulating film. The covering material 3 may be provided with adhesive layers on both sides of the insulating film.

The thickness of the covering material 3 is about 5 to 100 μm. From the viewpoint of weight reduction, it is preferable that the thickness of the covering material is small. The thickness of the covering material 3 may be 50 μm or less, 30 μm or less, 25 μm or less, or 23 μm or less.

The insulating film as the core layer of the covering material 3 has an in-plane anisotropy of the degree of molecular orientation, and has a molecular orientation axis in one direction in the film surface. The molecular orientation axis is the direction in which the degree of molecular orientation is the largest in the film plane. A film having an in-plane anisotropy of molecular orientation has high mechanical strength (tensile strength, tear strength, scratch resistance, wear resistance, etc.) when an external force is applied along a direction parallel to the molecular orientation axis. Tend.

A film having a molecular orientation axis is formed, for example, by stretching. In the film forming process, when the film is stretched in at least one direction, the polymer molecules are preferentially oriented in the stretching direction. A film having a molecular orientation axis in a predetermined direction can also be obtained by a relaxation treatment (a treatment of shrinking in at least one direction) instead of stretching.

A general stretched film has a molecular orientation axis in the transport direction (MD) at the time of film production or in the width direction (TD) orthogonal to the transport direction. When such a film is cut (slit) in a strip shape along the transport direction, the molecular orientation axis becomes parallel or orthogonal to the tape extending direction.

FIG. 2 is a plan view of a strip-shaped covering material used for forming a covering conductor. The covering material 3 is a strip-shaped tape. The molecular orientation axis p of the insulating film is neither parallel nor orthogonal to the longitudinal direction of the tape (direction along the BB line), and the angle (orientation) formed by the longitudinal direction of the covering material 3 and the molecular orientation axis p of the insulating film. Angle) φ is 10 to 80 °. The direction (orientation angle) of the molecular orientation axis can be measured by a microwave type molecular orientation meter, a birefringence meter (phase difference measuring device) using polarized light, or the like.

By producing a film having a molecular orientation axis oblique to the longitudinal direction and slitting it in a strip shape along the longitudinal direction, a coating material having a molecular orientation axis diagonally can be obtained. A film having a molecular orientation axis in the oblique direction can be produced, for example, by an oblique stretching method. By fixing both ends of the film in the width direction with a pin tenter, clip tenter, etc., and providing a difference in the traveling speed and traveling locus between the tenter at one end and the tenter at the other end, a diagonally stretched film having a molecular orientation axis in the oblique direction can be obtained. Be done. Specifically, a method of making the distance from the holding start point by the tenter at one end to the holding release point longer than the distance from the holding start point by the tenter at the other end to the holding release point, the traveling trajectory of the tenter (the tenter rail). A method of curving the entire shape), a method of moving the tenter at one end and the tenter at the other end along different traveling trajectories, a method of moving the tenter at one end and the tenter at the other end at different speeds, and the like can be mentioned. A plurality of these may be combined.

By adjusting the cutting direction of the film, a strip-shaped film having a molecular orientation axis in an oblique direction can also be obtained. For example, if a film having a molecular orientation axis parallel or orthogonal to the longitudinal direction is cut along a direction that is neither orthogonal nor parallel to the longitudinal direction, a strip-shaped film having an inclined molecular orientation axis can be obtained.

When the covering material has an adhesive layer on the surface of the insulating film, the slit may be performed after the adhesive layer is provided, or the adhesive layer may be provided on the film after the slit. From the viewpoint of productivity, a method of slitting a covering material having an adhesive layer on an insulating film into a predetermined width W is preferable.

[Wrapping of covering material]
A strip-shaped covering material 3 (hereinafter, also simply referred to as “insulating tape”) is spirally wound around the outer circumference of the conducting wire 1 to prepare a covering conductor. Wrapping of the insulating tape may be carried out by the same procedure as that for producing a general coated wire. As shown in FIG. 1, it is preferable to wind the spiral on the insulating tape 31 on the nth lap so that a part of the insulating tape 32 on the n + 1 lap overlaps.

3 and 4 are plan views showing a state in which an insulating tape 3 having a width W is wound around a conducting wire 1 having a diameter D and spirally wound at an angle θ. The winding angle θ is equal to the angle formed by the extending direction (AA wire) of the lead wire 1 and the longitudinal direction (BB wire) of the insulating tape 3.

As described above, the orientation axis p of the core layer (insulating film) of the insulating tape 3 is substantially parallel to the extending direction of the conducting wire 1. The angle ω formed by the molecular orientation axis p of the insulating film and the extending direction of the lead wire 1 is preferably 10 ° or less, more preferably 5 ° or less, still more preferably 3 ° or less. ω may be 2 ° or less, 1 ° or less, or 0 °.

The small ω tends to improve the wear resistance of the coated conductor. If the orientation axis p of the insulating film is parallel to the extending direction of the covering conductor, when an external force is applied along the extending direction of the covering conductor (when an external force is applied along the extending direction of the insulating film). ) The mechanical strength of the insulating film is high. Therefore, it is considered that the durability against rubbing along the extending direction is improved and the wear resistance is improved.

When the rotation direction of the BB line and the rotation direction of the orientation axis p are equal to each other with respect to the extension direction (AA line) of the lead wire 1, the relationship of ω = θ−φ is established. For example, in FIG. 3, the direction of the orientation axis p and the direction of the BB line are both counterclockwise with respect to the AA line, and ω = θ−φ is satisfied. As shown in FIG. 4, when the rotation direction of the BB line (counterclockwise with respect to the AA line) and the rotation direction of the orientation axis p (clockwise with respect to the AA line) are opposite. , Ω = φ−θ. That is, the angle ω is equal to the absolute value | θ−φ | of the difference between the winding angle θ and the orientation angle φ.

The winding angle θ is preferably φ-10 ° to φ + 10 °, more preferably φ-5 ° to φ + 5 °, and even more preferably φ-3 ° to φ + 3 °. θ may be in the range of φ ± 2 ° or φ ± 1 °.

The winding angle θ when spirally winding the insulating tapes so as to overlap is generally about 20 to 70 °, and the molecular orientation axis is parallel or orthogonal to the extending direction of the tape (the orientation angle φ is 0). (If ° or 90 °), ω will be between 20 ° and 70 °. If the insulating tape has a molecular orientation axis oblique to the longitudinal direction and the orientation angle φ is in the range of 10 ° to 80 °, ω can be adjusted within 10 °. In order to reduce ω, the orientation angle φ is more preferably 20 ° to 70 °, further preferably 30 ° to 65 °.

When the direction in which the insulating tape is wound (the front and back of the film) is reversed, the angle ω is different. The direction in which the insulating tape is wound may be set so that the angle ω becomes small. If the insulating film is wound in a direction in which the angle ω becomes smaller, the winding angle θ, the orientation angle φ, and the angle ω satisfy ω = | θ−φ | as described above.

The width W of the insulating tape 3 and the winding angle θ may be adjusted so that the overlap ratio Rp of the insulating tape on the coated conductor is within a predetermined range. The overlap ratio (also referred to as “wrap ratio”) Rp uses the overlap width Q (see FIG. 1) between the insulating tape 31 on the nth lap of the spiral and the insulating tape 32 on the n + 1 lap, and the width W of the insulating tape. , Defined by the following formula.
Rp (%) = 100 x Q / W

When the overlap ratio Rp is greater than 0 and less than 50%, when looking along the extending direction of the lead wire 1, the insulating tape is double-wound around the outer circumference of the lead wire in some areas, and the lead wire is double-wrapped in other regions. A single layer of insulating tape is wrapped around the outer circumference of the cable. When the overlap ratio Rp is 50%, the insulating tape is doubly wound around the outer circumference of the lead wire in the entire region. When the overlap ratio Rp is larger than 50% and less than 66.7%, there are a region where the insulating tape is double-wound and a region where the insulating tape is triple-wound. When the overlap ratio Rp is 66.7%, the insulating tape is triple-wrapped around the outer circumference of the lead wire in the entire area, and when the overlap ratio Rp is larger than 66.7% and less than 75%, the insulating tape is used. There is a triple-wound area and a quadruple-wound area.

The diameter D of the conducting wire, the width W of the insulating tape, the overlapping width Q of the insulating tape, the overlapping ratio Rp, and the winding angle θ satisfy the following relationships.
πD × cos θ = W−Q = W × (1-Rp / 100)

Due to restrictions on equipment, product specifications, etc., the diameter D of the lead wire, the width W of the insulating tape, and the overlap ratio Rp may be set to predetermined values. In that case, since the winding angle θ is also a constant value, the orientation angle φ of the insulating tape 31 may be adjusted so that the angle ω is within the above range. On the other hand, when the orientation angle φ of the insulating tape is a predetermined value, the winding angle θ may be adjusted so that the angle ω is within the above range. When the diameter D of the conducting wire, the orientation angle φ of the insulating tape, and the overlap ratio Rp are set to predetermined values, the slit width W of the insulating tape may be adjusted in addition to the winding angle θ.

The insulating tape 3 may be wound around the lead wire 1 by using a standard electric wire covering machine (wrapping machine) or the like. The tension applied to the insulating tape during wrapping can vary widely, from a tension sufficient to avoid wrinkling to a range of tension strong enough to cause neck down. it can. Even if the tension is low, the insulating tape shrinks due to the heat during heat sealing after winding (for example, 240 ° C. to 500 ° C.), so that the lead wire can be covered with good adhesion. When heat sealing is performed, the conditions may be appropriately set according to the thickness of the insulating tape (insulating film and adhesive layer), the material of the conducting wire, the speed of the production line, the length of the oven, and the like.

After wrapping the insulating tape 3 around the lead wire 1, another insulating material may be overlapped and wound. Another insulating material overlaid on the insulating tape may or may not have an orientation axis. Another insulating material overlaid on the insulating tape has an orientation axis, and if the orientation axis direction is (omitted) parallel to the extending direction of the conductor, the wear resistance of the coated conductor tends to be further improved.

[Preferable form of insulating coating material]
As described above, the insulating coating material (insulating tape) 3 includes an insulating film, and preferably has an adhesive layer on at least one surface of the insulating film.

<Insulation film>
As the insulating film, a film made of various polymer materials can be used. The insulating film may contain a filler. Examples of the filler material include silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, and mica.

As the polymer material of the insulating film, polyurethane resin, poly (meth) acrylic resin, polyvinyl resin, polystyrene resin, polyethylene resin, polypropylene resin, polyimide resin, polyamide resin, polyacetal resin, polycarbonate resin, polyester resin, polyphenylene ether resin, polyphenylene. Examples thereof include sulfide resin, polyether sulfone resin, and polyether ether ketone resin. Among these, a film containing a polyimide resin (polyimide film) is preferable because it is excellent in various properties such as heat resistance, electrical insulation, chemical resistance, and flame retardancy.

(Polyimide film)
The method for producing the polyimide film is not particularly limited, but it is generally obtained by forming a polyamic acid as a precursor into a film and then dehydrating and cyclizing (imidizing) the polyamic acid. Polyamide acid is usually polymerized by dissolving diamine and tetracarboxylic dianhydride (hereinafter, may be simply referred to as "acid dianhydride") in an organic solvent in substantially equal molar amounts. Obtained by

As the diamine, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfide, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 4, 4'-oxydianiline, 3,3'-oxydianiline, 3,4'-oxydianiline, 4,4'-diaminodiphenyldiethylsilane, 4,4'-diaminodiphenylsilane, 4,4'-diamino Diphenylethylphosphine oxide, 4,4'-diaminodiphenyl-N-methylamine, 4,4'-diaminodiphenyl-N-phenylamine, paraphenylenediamine, bis {4- (4-aminophenoxy) phenyl} sulfone, bis {4- (3-Aminophenoxy) phenyl} sulfone, 4,4'-bis (4-aminophenoxy) biphenyl, 4,4'-bis (3-aminophenoxy) biphenyl, 1,3-bis (3-amino) Phenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 3,3'-diaminobenzophenone , 4,4'-diaminobenzophenone, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2-bis (4-aminophenoxyphenyl) propane, 3,3'-dihydroxy-4,4'- Examples thereof include diamino-1,1'-biphenyl and the like. Among these, para-phenylenediamine (PDA, 4,4'-oxydianiline (ODA), 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP), 3,4'-oxydi Aniline and 1,3-bis (4-aminophenoxy) benzene are preferred.

Examples of the acid dianhydride include pyromellitic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3', 4,4'-benzophenonetetracarboxylic dianhydride, 2, 2', 3,3'-biphenyltetracarboxylic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propanoic acid Examples thereof include dianhydride, p-phenylenebis (trimellitic acid monoesteric dianhydride), 4,4'-oxydiphthalic dianhydride and the like. Among these, pyromellitic dianhydride (PMDA), 3,3', 4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 3,3', 4,4'-biphenyltetracarboxylic dianhydride Anhydride (BPDA) is preferred.

The organic solvent used for the polymerization of the polyamic acid is not particularly limited as long as the polyamic acid can be dissolved. As the organic solvent, amide-based solvents such as N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc) and N-methyl-2-pyrrolidone (NMP) are preferable, and DMF and DMAc are particularly preferable.

Polymerization of polyamic acid proceeds by dissolving a monomer (diamine and acid dianhydride) in an organic solvent and stirring the mixture. The monomer may be added at once or may be added in a plurality of times. By adjusting the order of adding the monomers, the sequence of the monomers can be adjusted and various physical properties of the polyimide can be controlled. For example, a block copolymer may be formed by forming a segment having a flexible chemical structure as a first step and then forming a segment having a rigid chemical structure as a second step.

The segment having a flexible chemical structure preferably contains ODA as a diamine component and BTDA as an acid dianhydride. The acid dianhydride component preferably contains 10 to 30 mol% of BTDA, and the diamine component preferably contains 40 to 60 mol% of ODA. The segment having a rigid chemical structure preferably contains PDA, PMDA, BPDA, etc. as an acid dianhydride component, and more preferably contains PDA and PMDA as main components. It is preferable that 40 to 60 mol% of the diamine component of the entire polyimide is PDA, and 45 mol% to 65 mol% of the acid dianhydride component of the entire polyimide is PMDA.

The imidization when producing the polyimide film from the polyamic acid solution may be either a thermal imidization method or a chemical imidization method, or both may be used in combination. In chemical imidization, it is preferable to add a dehydrating agent and an imidization catalyst to the polyamic acid solution. As the dehydrating agent, an acid anhydride such as acetic anhydride is preferable. As the imidization catalyst, tertiary amines such as isoquinoline, quinoline, β-picoline, pyridine, dimethylpyridine and diethylpyridine are preferable.

In the preparation of a polyimide film from a polyamic acid solution, generally, the polyamic acid solution is cast on a support, heated on the support, and then the gel film is peeled off from the support to hold both ends of the gel film. It is carried out by heating while transporting the film to remove the solvent and the like and imidize the remaining amic acid. By peeling the gel film from the support and then stretching it, a polyimide film having an orientation axis in a predetermined direction can be obtained.

When the gel film is stretched and the molecules are oriented in a predetermined direction, the amount of residual volatile components (gel residual volatilization) of the gel film is preferably 60 to 500 parts by weight, preferably 100 to 400 parts by weight, based on 100 parts by weight of the solid content. More preferred. When the gel residual volatilization is 500 parts by weight or less, the molecular orientation angle of the polyimide film tends to be uniform, and when the gel residual volatilization is 60 parts by weight or more, the smoothness of the polyimide film tends to be good.

(Molecular orientation of insulating film)
There is a degree of molecular orientation (MOR) as an index showing the degree of orientation of molecules in a polymer film. MOR is measured using a microwave type molecular orientation meter. When measuring the degree of molecular orientation of the insulating film in the coating material after forming the adhesive layer, the adhesive layer is removed and the measurement is performed with the insulating film alone.

When the MOR is 1, the molecular orientation is isotropic, and the film having a MOR greater than 1 has an in-plane anisotropy of the degree of molecular orientation. The larger the MOR, the larger the in-plane anisotropy of the molecular orientation, and the more the wear resistance of the coated conductor tends to be improved.

When the degree of anisotropy of molecular orientation is the same, the larger the thickness of the sample (film), the larger the value of MOR measured by the molecular orientation meter. Therefore, when evaluating the degree of anisotropy of molecular orientation, normalized molecular orientation: MOR_c converted to a predetermined reference thickness is used.
MOR_c = (tc / t) × (MOR-1) +1
t is the thickness of the sample and tc is the reference thickness.

The molecular orientation degree MOR_c standardized with the reference thickness tk = 75 μm of the insulating film is preferably 1.3 or more, more preferably 1.4 or more, and further preferably 1.5 or more. MOR_c may be 1.6 or more, 1.7 or more, or 1.8 or more. The larger the MOR_c of the insulating film, the more the wear resistance of the coated conductor tends to improve. The upper limit of MOR_c is not particularly limited, but is generally 5 or less. MOR_c may be 4 or less or 3 or less.

The thickness of the insulating film is not particularly limited. From the viewpoint of reducing the weight of the coated conductor, it is preferable that the thickness of the insulating film is small. The thickness of the insulating film is preferably 25 μm or less, more preferably 20 μm or less, and even more preferably 19 μm or less. The thickness of the insulating film may be 18 μm or less. As described above, in the present invention, the wear resistance can be improved by making the molecular orientation axis of the insulating film substantially parallel to the extending direction of the conducting wire, so that the wear resistance can be improved even when the thickness of the insulating film is small. An excellent coated conductor can be formed.

The lower limit of the thickness of the insulating film is not particularly limited, but is preferably 5 μm or more, and more preferably 7 μm or more from the viewpoint of ensuring handleability and mechanical strength. The thickness of the insulating film and the thickness of the covering material are measured using a contact thickness meter.

<Adhesive layer>
The material of the adhesive layer of the insulating coating material is not particularly limited as long as it can improve the adhesiveness between the conducting wire and the insulating film. A thermoplastic resin is preferable because the adhesiveness can be improved by heat sealing, and a fluororesin is particularly preferable from the viewpoint of insulating property and chemical resistance.

Fluororesin is a polymer containing a fluorine atom in its molecule, and is a tetrafluoroethylene polymer, a tetrafluoroethylene / hexafluoropropylene copolymer, a tetrafluoroethylene / perfluoro (alkyl vinyl ether) copolymer, or a tetrafluoroethylene / ethylene. Examples thereof include copolymers, polychlorotrifluoroethylene, ethylene / chlorotrifluoroethylene copolymers, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymers and polyvinyl fluoride. Of these, a tetrafluoroethylene polymer or a tetrafluoroethylene perfluoro (alkyl vinyl ether) copolymer is preferable.

The thickness of the adhesive layer is not particularly limited as long as the adhesiveness can be exhibited, and is, for example, about 0.5 to 13 μm. A plurality of adhesive layers may be formed on one surface of the insulating film. When the adhesive layers are provided on both sides of the insulating film, the materials and thicknesses of the adhesive layers on the front and back surfaces may be the same or different. The surface of the adhesive layer and the surface of the insulating film may be subjected to surface treatment such as corona discharge treatment or plasma discharge treatment for the purpose of improving adhesiveness.

As a method of forming an adhesive layer on the main surface of a smoke-saving film, a method of laminating a film-like adhesive layer, a method of forming an insulating film as a core layer and an adhesive layer by multi-layer coextrusion, and a method of forming an adhesive layer on an insulating film. Examples thereof include a method of applying a solution or a dispersion (dispersion) containing a resin constituting the adhesive layer. As the dispersion, a resin material constituting the adhesive layer dispersed in water or an organic solvent is used. The solid component concentration of the dispersion is about 10 to 70% by weight. The dispersion may be applied multiple times until a suitable thickness is reached. After forming the adhesive layer on the main surface of the insulating film, heating and firing may be performed.

[Use of coated conductor]
The coated conductor is used for various electric wires, cables and the like. Since the coated conductor of the present invention has excellent wear resistance, it is also useful as an electric wire / cable for aerospace.

The present invention will be described in more detail with reference to Examples below, but the present invention is not limited to the following Examples.

[Measuring method]
<Molecular orientation axis and degree of molecular orientation of polyimide film>
The degree of molecular orientation (MOR) and orientation angle (φ) of the polyimide film were determined using a microwave type molecular orientation meter (“MOA-6015” manufactured by Oji Measuring Instruments). From the thickness t of the polyimide film and the reference thickness tc = 75 μm, the molecular orientation degree MOR_c standardized at the reference thickness of 75 μm was calculated based on the following formula.
MOR_c = (tc / t) (MOR-1) +1

<Abrasion resistance of coated conductor>
Using a scrape wear tester (WELLMAN's "REPEATED SCRAPE ABRASION TESTER (CAT.158L238G1)", British Standards Association aircraft parts specifications (British Standard Aerospace Series) "BS EN3475-503" The average value of the five test values was taken as the number of times the coated conductor was abraded.

[Example 1]
<Preparation of polyimide precursor>
326.0 kg of dimethylformamide (DMF) was added to the polymerization vessel, and 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP): 14.7 kg, 4,4'-oxydianiline (ODA). ): After adding 6.6 kg, 3,3', 4,4'-benzophenonetetracarboxylic dianhydride (BTDA): 9.8 kg, and pyromellitic dianhydride (PMDA): 6.9 kg in order. , Stirred for 50 minutes to dissolve. Then, 7.5 kg of para-phenylenediamine (PDA) and 15.6 kg of PMDA were added and stirred for 1 hour to dissolve. A separately adjusted DMF solution of PMDA (7 wt%) was gradually added to the above reaction solution, and the addition was stopped when the viscosity at 23 ° C. reached 2400 poisons to obtain a polyimide precursor (polyamic acid solution). ..

<Manufacturing of polyimide film>
The following amounts of acetic anhydride (chemical dehydrating agent) and isoquinolin (catalyst) were added to the above-mentioned polyimide precursor, and DMF was further added to prepare a varnish having a solid content concentration of 10 wt%.
Acetic anhydride: 2.7 mol per mol of amic acid unit of polyamic acid Isoquinoline: 0.6 mol per mol of amic acid unit of polyamic acid

The above varnish is continuously discharged from a die having a lip width of 520 mm cooled to 0 ° C., cast on an endless belt made of SUS, and heated stepwise for 100 seconds in the range of 50 ° C. to 100 ° C. , A gel film having self-supporting property. Both ends of the gel film peeled off from the endless belt were fixed to the tenter, and the tenter was gradually heated in the range of 20 ° C. to 100 ° C. while moving the tenter in the longitudinal direction. At this time, stretching was performed in an oblique direction with the difference in running speed between the left and right tenters being 10%.

Then, it was heated stepwise in the range of 150 ° C. to 400 ° C. to dry and imidize. The thickness of the obtained polyimide film was 17 μm, the orientation angle φ with respect to the longitudinal direction was 32 °, and MOR_c was 2.0.

<Manufacturing of insulating coating material>
An aqueous dispersion of tetrafluoroethylene / hexafluoropropylene copolymer (FEP) was applied to both sides of the polyimide film, dried at 150 ° C. for 65 seconds, and then fired at 410 ° C. for 15 seconds to form both sides of the polyimide film. A laminate having a FEP layer having a thickness of about 2 μm was obtained for each. This laminate was slit into a strip having a width of 5.0 mm to obtain an insulating tape.

<Manufacturing of coated conductor>
A conductor wire with a diameter of 0.8 mm ("High performance angle copper coated copper" (AWG: 20, CONST: 19/32) manufactured by Philps doges) has an overlapping width Q of 2.5 mm and an overlap ratio Rp of 50% (AWG: 20, CONST: 19/32). The above-mentioned insulating tape was spirally wound at a winding angle θ = 28 ° so as to be double-wound) to prepare a coated conductor. The angle ω formed by the extending direction of the conducting wire and the molecular orientation axis of the polyimide film was 4 °.

[Examples 2 to 4 and Comparative Examples 3 and 4]
In the production of the polyimide film, the difference in running speed between the left and right tenters when the gel film was conveyed while being heated stepwise in the range of 20 ° C. to 100 ° C. was changed as shown in Table 1. Further, the slit width W of the tape and the winding angle θ were changed as shown in Table 1. In Comparative Example 4, in the production of the polyimide film, the discharge amount of the varnish from the die was reduced to 60% of that of Example 1 to adjust the thickness, and in the production of the coated conductor, the overlap ratio Rp of the insulating tape was 66.7. The winding angle θ was adjusted so as to be% (triple winding). A coated conductor was produced in the same manner as in Example 1 except for these changes.

[Examples 5 to 7 and Comparative Example 2]
In the production of the polyimide film, when the gel film is conveyed while being heated stepwise in the range of 20 ° C. to 100 ° C., the difference in running speed between the left and right tenters is changed as shown in Table 1, and the distance between the left and right tenters is changed. The distance was reduced by 4%. Further, the slit width W of the tape and the winding angle θ were changed as shown in Table 1. In Example 7, in the production of the polyimide film, the discharge amount of the varnish from the die was reduced to 70% of that in Example 1 to adjust the thickness, and in the production of the coated conductor, the overlap ratio Rp of the insulating tape was 66.7. The winding angle θ was adjusted so as to be% (triple winding). A coated conductor was produced in the same manner as in Example 1 except for these changes.

[Comparative Example 1]
In the production of the polyimide film, when the gel film is conveyed while being heated stepwise in the range of 20 ° C. to 100 ° C., the distance between the left and right tenters is increased by 18% without providing a difference in running speed between the left and right tenters. , Stretched in the width direction. A coated conductor was produced in the same manner as in Example 1 except for the above.

[Evaluation results]
Table 1 shows the stretching conditions of the polyimide film (gel film), the characteristics of the polyimide film, the manufacturing conditions of the coated conductor, and the evaluation results of the wear resistance in the above Examples and Comparative Examples.

The coated conductors of Examples 1 to 7 had a wear resistance of more than 400 times, and exhibited excellent wear resistance. From the comparison between the examples and the comparative examples, it can be seen that the smaller the angle ω formed by the extending direction of the conducting wire and the orientation axis of the polyimide film, the better the wear resistance tends to be. Further, from the comparison between Example 1 and Example 6, it can be seen that when the angle ω is about the same, the larger the degree of molecular orientation of the polyimide film, the higher the wear resistance of the coated conductor.

1 Lead wire 3 Insulation coating material (insulation tape)

Claims (8)

A coated conductor in which a band-shaped insulating coating material is spirally wound around the outer circumference of a conducting wire extending in the first direction.
The insulating coating material contains an insulating film and contains an insulating film.
The angle φ formed by the molecular orientation axis of the insulating film and the longitudinal direction of the insulating coating material is 10 ° to 80 °, and the angle ω formed by the molecular orientation axis of the insulating film and the first direction is 10 ° or less. Is a coated conductor. The coated conductor according to claim 1, wherein the insulating film contains polyimide. The coated conductor according to claim 1 or 2, wherein the molecular orientation degree MOR_c standardized with a reference thickness of 75 μm of the insulating film is 1.3 or more. The coated conductor according to any one of claims 1 to 3, wherein the insulating coating material includes an adhesive layer on at least one main surface of the insulating film. The coated conductor according to claim 4, wherein the adhesive layer contains a fluororesin. A method for manufacturing a coated conductor in which a band-shaped insulating coating material is spirally wound around the outer circumference of a conducting wire extending in the first direction.
The insulating coating material includes an insulating film, and the angle φ formed by the molecular orientation axis of the insulating film and the longitudinal direction of the insulating coating material is 10 ° to 80 °.
A method for manufacturing a coated conductor, in which the insulating coating material is wound around the outer periphery of the conducting wire so that the angle ω formed by the molecular orientation axis of the insulating film and the first direction is 10 ° or less. The sixth aspect of the present invention, wherein the insulating film of the insulating coating material is a diagonally stretched film having an angle formed by a transport direction and a molecular orientation axis of 10 ° to 80 °, slit in parallel with the transport direction. A method for manufacturing a coated conductor. The insulating film of the insulating coating material is a film having a molecular orientation axis in a direction parallel to or orthogonal to the transport direction, slit along a direction of 10 ° to 80 ° with respect to the transport direction. The method for producing a coated conductor according to 6.

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