JP2014105258A - Resin composition for extrusion molding and method for producing the same, and insulated cable employing said resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition and method for producing the same that realizes an insulated cable being provided with an extrusion coating layer having a high partial discharge inception voltage and having a good extrusion moldability.SOLUTION: The resin composition comprises a polymer alloy, and is characterized in that the polymer alloy has a sea-island structure and the sea component of the sea-island structure is a polyphenylene sulfide (resin A) and the island component of the sea-island structure is a fluororesin (resin B) having an equivalent circle mean diameter of 10 μm or less and the mixture ratio of the resin A and the resin B is 60/40≤(resin A)/(resin B)≤80/20 in weight parts ratio. The resin composition can be applied to the extrusion coating layer 4 of the insulated cable.

Description

  The present invention relates to an insulated wire used for a coil of an electric device such as a rotating electrical machine or a transformer, and in particular, a resin composition suitable for extrusion molding and a method for producing the same, and an insulation coating including an extrusion coating layer are formed. It relates to an insulated wire.

  Insulated wires used in coils of electrical equipment such as rotating electrical machines and transformers are generally outer peripheries of conductors that have been formed into a cross-sectional shape (for example, a round shape or a quadrilateral shape) that matches the application and shape of the coil. It has a structure in which a single-layer or multiple-layer insulation coating is formed. As a method for forming the insulating coating, there are a method in which an insulating paint in which a resin is dissolved in an organic solvent is applied and baked on the conductor, and a method in which a resin composition prepared in advance is coated on the conductor by extrusion.

  In recent years, due to the demand for miniaturization of electrical equipment, insulated wires have been wound at high density around small diameter cores under high tension in the coil forming process, and the insulation coating is a machine that can withstand severe processing stress. Characteristics (for example, adhesion to a conductor and wear resistance) are required. In addition, inverter control and higher voltage are progressing due to demands for higher efficiency and higher output of electrical equipment. As a result, the temperature of the coil during the operation of the electric equipment has a tendency to rise more than before, and the insulating coating is also required to have high heat resistance. In addition, since a higher voltage such as an inverter surge voltage is applied to the coil in the electric device, there has been a problem that the insulation coating may be deteriorated or damaged due to the occurrence of partial discharge.

  In order to prevent deterioration and damage of the insulation coating due to partial discharge, development of insulation coating with a high partial discharge starting voltage is underway. Examples of means for increasing the partial discharge start voltage of the insulating coating include a method using a resin having a low relative dielectric constant for the insulating coating and a method of increasing the thickness of the insulating coating.

  In Patent Document 1 (Japanese Patent No. 4177295), at least one enamel baked layer is provided on the outer periphery of the conductor, and at least one extruded coating resin layer is provided on the outer side of the conductor, and the enamel baked layer and the extruded coating resin are provided. The total thickness of the layers is 60 μm or more, the thickness of the enamel baked layer is 50 μm or less, the extrusion-coated resin layer has a tensile elastic modulus at 25 ° C. of 1000 MPa or more, and a tensile strength at 250 ° C. An inverter surge resistant wire characterized by being made of a resin material (excluding polyether ether ketone) having an elastic modulus of 10 MPa or more is disclosed. The insulated wire described in Patent Document 1 is said to be able to provide an insulated wire having a high partial discharge starting voltage (about 900 Vp) without reducing the adhesive strength between the conductor and the insulating coating layer.

Moreover, in patent document 2 (Unexamined-Japanese-Patent No. 11-269383), following (a) and the following (b), (a) 50-99.5 weight% in the total amount of (a) and (b), (B) It is contained at a ratio of 0.5 to 50% by weight, and the following (c) is a total amount, more than 0 part by weight and not more than 250 parts by weight with respect to 100 parts by weight of the total amount of (a) and (b) (A) is polyphenylene sulfide, and (b) is melted in a nitrogen atmosphere at 330 ° C. and then cooled at a cooling rate of 10 ° C./min, the solidification temperature (T _mc ) is 237 A fluororesin having a melt index of not less than 0.1 g / 10 min under a measurement condition of not less than ℃, a melt viscosity of 330 ° C., a load of 5 kg, an orifice of 2.095 mm in diameter and a length of 8 mm, (c) A resin composition that is one or more selected from the group consisting of organic reinforcing materials, inorganic reinforcing materials, and fillers is disclosed. The resin composition described in Patent Document 2 has extremely high dimensional accuracy of a molded product having a three-dimensional shape obtained by injection molding, and is useful for structural materials and various parts in the fields of automobiles, home appliances, and electronics. And it is.

  Moreover, in patent document 3 (Unexamined-Japanese-Patent No. 2011-134447), it is the insulated wire in which the insulation coating which consists of several coating layers containing at least 1 extrusion coating layer is formed on the conductor, Comprising: Said at least 1 The extrusion coating layer is a layer obtained by extrusion coating a resin composition comprising a polyphenylene sulfide resin (A) and an olefin copolymer resin (B), and the resin composition comprises the polyphenylene sulfide resin (A) and the olefin. An insulated wire characterized in that the copolymer resin (B) is mixed in the range of “(B) / (A) = 45/55 to 70/30” by weight ratio is disclosed. . The insulated wire described in Patent Document 3 is said to have a partial discharge start voltage higher than that of the prior art while having heat resistance and insulating coating thickness equivalent to those of the conventional one.

Japanese Patent No. 4177295 Japanese Patent Laid-Open No. 11-269383 JP 2011-134447 A

  The conventional insulated wire having the extrusion-coated resin layer described in Patent Document 1 is considered to be able to increase the partial discharge start voltage by increasing the thickness of the extrusion-coated resin layer. Moreover, in order to ensure the adhesiveness of an extrusion coating resin layer, the enamel baking layer is interposed between the conductor and the extrusion coating resin layer. Further, as a preferred embodiment, an adhesive layer is further interposed between the enamel baked layer and the extrusion-coated resin layer to enhance the adhesive force between the enamel baked layer and the extrusion-coated resin layer.

  However, all of these measures in Patent Document 1 are in the direction of increasing the thickness of the entire insulation coating, and it is difficult to meet the demands for downsizing the coil and improving the conductor space factor. In addition, since the properties of the resin composition and the forming method are greatly different between the enamel baking layer and the extrusion-coated resin layer, the insulated wire of Patent Document 1 has a problem that the manufacturing process is likely to be complicated and the manufacturing cost is likely to increase. is there. In addition, when an adhesive layer is further interposed between these layers, there is a problem that the manufacturing cost further increases.

  Moreover, since the resin composition described in Patent Document 2 has been proposed as an injection molding material, and the shape of the molded product is controlled by a mold, the properties of the resin composition (for example, microstructure, Regardless of the surface shape in a free state that is not constrained in shape, the surface of the molded product becomes smooth with the accuracy of the mold surface. However, in extrusion molding, the pressure is released in the free space after exiting the extruder (passing through the extrusion die), so that the surface of the molded product will be excessively uneven unless the properties of the resin composition are controlled well. It may cause it. Excessive unevenness generated on the surface of the insulation coating in an insulated wire reduces the controllability of the coil forming process and reduces the space factor in the coil (that is, hinders downsizing of the coil) or partial discharge. This is not preferable because it causes a decrease in the starting voltage. In other words, the resin composition described in Patent Document 2 is not necessarily suitable for the insulation coating (especially the extrusion coating layer) of the insulated wire used for the coil of the electric device that is controlled by the inverter and the voltage is increased. I can not say.

  Along with the downsizing of electrical equipment, the coil is required to be further downsized while maintaining (or improving) its performance, and the need for high-density winding is increasing. ing. In addition, the demand for cost reduction is increasing. For these reasons, the improvement in shape controllability (extrusion formability) by extrusion molding has become more important than the prior art from the viewpoint of high-density winding and cost reduction. The insulated wire described in Patent Document 3 has a high partial discharge start voltage while having the same heat resistance and insulation coating thickness as the conventional one, but further improved extrusion moldability from the above viewpoint. Was desired.

  Accordingly, an object of the present invention is to satisfy the above-described requirements, and to provide an insulated wire having an extrusion coating layer having a high partial discharge start voltage and having a good extrusion moldability, and a resin composition therefor It is to provide a manufacturing method. Moreover, it is providing the insulated wire which comprises the extrusion coating layer using this resin composition.

  (I) In order to achieve the above object, the present invention provides a resin composition comprising a polymer alloy, wherein the polymer alloy has a sea-island structure, and the sea component of the sea-island structure is polyphenylene sulfide (resin A). The island component of the sea-island structure is a fluororesin (resin B) having an equivalent circular average diameter of 10 μm or less, and the mixing ratio of the resin A and the resin B is “60/40 ≦ (resin A ) / (Resin B) ≦ 80/20 ”is provided. In the present invention, the equivalent circle average diameter of the island means the average diameter of a circle (equivalent circle) showing the same area as the area of each island part of the sea-island structure obtained from cross-sectional observation.

(II) In order to achieve the above object, the present invention provides a method for producing a resin composition comprising a polymer alloy, wherein the polymer alloy has a sea-island structure, and the sea component of the sea-island structure is polyphenylene sulfide (resin A ), And the island component of the sea-island structure is a fluororesin (resin B) having an equivalent circular average diameter of 10 μm or less,
The manufacturing method includes a kneading step of kneading the resin A and the resin B having a predetermined mixing ratio by rotation of a screw in a cylinder of an extruder to form the polymer alloy, and downstream of the cylinder. And an extrusion step of discharging the polymer alloy from an extrusion die,
The predetermined mixing ratio is “60/40 ≦ (resin A) / (resin B) ≦ 80/20” by mass part ratio,
In the kneading step, when the clearance between the tip of the cylinder and the screw is c [unit m] and the peripheral speed of the tip of the screw is v [unit m / s], the resin A and the resin B And the shear rate applied to is "v / c ≥ 1200 s ^-1 "
The extruding step provides a method for producing a resin composition, characterized in that the residence time of the polymer alloy from leaving the cylinder to passing through the extrusion die is within 5 minutes.

In order to achieve the above object, the present invention can be modified or changed as follows in the resin composition (I) and the method (II) for producing a resin composition according to the present invention.
(I) The resin A has a melt flow rate at 330 ° C. of 10 g / 10 min to 22 g / 10 min, and the resin B has a melt flow rate at 330 ° C. of 5 g / 10 min to 40 g / 10 min. .

  (III) In order to achieve the above object, the present invention is an insulated wire in which an insulation coating having an extrusion coating layer is formed on a conductor, and the extrusion coating layer comprises the resin composition according to the present invention. An insulated wire characterized by the above is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the resin composition for enabling the insulated wire which has the extrusion coating layer which has a high partial discharge start voltage and has favorable extrusion property can be provided, and its manufacturing method. Moreover, the insulated wire which has a favorable external appearance without a surface unevenness | corrugation can be provided by using the resin composition which concerns on this invention as an extrusion coating layer.

It is a cross-sectional schematic diagram which shows an example of embodiment of the insulated wire which concerns on this invention. It is a cross-sectional schematic diagram which shows another example of embodiment of the insulated wire which concerns on this invention. It is a schematic diagram which shows an example of the extruder used for manufacture of the resin composition which concerns on this invention. It is a schematic diagram which shows the cylinder cross section of the extruder shown in FIG.

  In the insulated wire in which the insulation coating having the extrusion coating layer is formed on the conductor, the present inventors have various characteristics described above required for the extrusion coating layer (high heat resistance, high partial discharge starting voltage, good extrusion moldability). ), The composition and structure (morphology) of the resin composition constituting the extrusion coating layer were studied earnestly. As a result, it has been found that an extruded coating layer in which a predetermined sea-island structure is formed with a polymer alloy formed from a polyphenylene sulfide and a fluororesin having a predetermined mixing ratio can satisfy the above requirements. The present invention has been completed based on these findings.

  Embodiments according to the present invention will be described below. However, the present invention is not limited to the embodiments taken up here, and can be appropriately combined and improved without departing from the technical idea of the present invention.

(Insulated wire)
FIG. 1 is a schematic cross-sectional view illustrating an example of an embodiment of an insulated wire according to the present invention, and illustrates a case where the insulating coating has a single-layer structure. In an insulated wire 10 according to the present invention, an insulating coating 2 made of an extrusion coating layer 4 is formed on a conductor 1, and the extrusion coating layer 4 is composed of a resin composition according to the present invention described later. FIG. 2 is a schematic cross-sectional view illustrating another example of the embodiment of the insulated wire according to the present invention, and illustrates the case where the insulating coating has a multi-layer structure. As shown in FIG. 2, the insulated wire 20 according to the present invention has an adhesive layer 3 for improving the adhesion between the conductor 1 and the extrusion coating layer 4 and improving the heat resistance of the insulation coating 2. An outermost layer 5 is provided on the outer periphery of the extrusion coating layer 4 to improve the wear resistance and / or the slipperiness of the insulating coating 2.

  As the adhesive layer 3 and the outermost layer 5, conventional techniques can be used. For example, at least one selected from the group consisting of polyamide, thermoplastic polyamideimide, thermoplastic polyimide, polyetherimide, and polyphenylene sulfide is mainly used. Resins as components can be suitably used. In addition, you may add antioxidant, a copper damage inhibitor, a lubricant, a coloring agent, etc. in the resin composition which comprises each layer as needed.

  Further, the method for forming the adhesive layer 3 and the outermost layer 5 is not particularly limited, but it is preferable that these layers and the extrusion coating layer 4 are brought into contact (bonded) in a heated state. By bringing the resins constituting each layer into contact with each other at a high temperature, the adhesion between the layers can be further improved, and the mechanical strength of the insulating coating 2 as a whole can be easily secured.

  The thicknesses of the adhesive layer 3, the extrusion coating layer 4 and the outermost layer 5 are each preferably 10 μm or more. If the thickness is less than 10 μm, the function (characteristics) of each layer cannot be fully exhibited. The total thickness of the insulating coating 2 is appropriately selected within the range of 30 to 500 μm according to the required performance of the insulated wire.

  There is no particular limitation on the material of the conductor 1, and materials commonly used for insulated wires (for example, oxygen-free copper, low-oxygen copper, etc.) can be used. In FIGS. 1 and 2, the conductor 1 has an example having a round cross section. However, the conductor 1 is not limited thereto, and may be a conductor having a quadrilateral cross section. The quadrilateral shape in the present invention includes a quadrangular shape with rounded corners and a rounded rectangular shape.

(Resin composition)
As described above, the resin composition according to the present invention comprises a polymer alloy having a sea-island structure which is a kind of phase separation structure, and the sea component of the sea-island structure is polyphenylene sulfide (resin A), and the island component of the sea-island structure. Is a fluororesin (resin B) having an equivalent circular average diameter of 10 μm or less, and the mixing ratio of the resin A and the resin B is “60/40 ≦ (resin A) / (resin B) ≦ 80 / 20 ”.

  Polyphenylene sulfide is a resin that excels in heat resistance, mechanical strength, and chemical resistance, but when used alone as an insulation coating material, its relative dielectric constant is not particularly low, so it is a weak point in terms of partial discharge starting voltage. There is. Fluororesin has the advantages of excellent heat resistance and chemical resistance and low dielectric constant. However, when used alone as an insulation coating material, it has low adhesion to conductors, so it is insulated by mechanical stress. Peeling from the conductor may occur (coating floating). Therefore, in the present invention, the characteristics of the resin composition as a whole are improved by alloying polyphenylene sulfide and a fluororesin to form a sea-island structure.

  Examples of the fluororesin (resin B) include tetrafluoroethylene / hexafluoropropylene copolymer (FEP), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), polyvinylidene fluoride (PVDF), and tetrafluoroethylene. -An ethylene copolymer (ETFE) can be preferably used. Among these, FEP can be particularly preferably used from the viewpoint of moldability and kneadability.

  As described above, the mixing ratio of the resin A and the resin B in the polymer alloy is preferably “60/40 ≦ (resin A) / (resin B) ≦ 80/20” by mass ratio. When the mass part ratio between the resin A and the resin B is “80/20 <(resin A) / (resin B)”, the resin B is too small and the effect of reducing the relative dielectric constant becomes insufficient. On the other hand, when the mass part ratio between the resin A and the resin B is “(resin A) / (resin B) <60/40”, the extrusion moldability of the resin composition cannot be kept good.

  In addition, if the equivalent circular average diameter of the island due to resin B exceeds 10 μm or the sea-island structure collapses (that is, if a large lump of resin B is unevenly distributed in the polymer alloy), the electrical properties / mechanics of the resin composition The characteristics and extrusion moldability fluctuate greatly locally, making it impossible to satisfy various characteristics required for insulation coating.

  The resin A is preferably a resin having a melt flow rate (MFR) of 10 g / 10 min to 22 g / 10 min. Resin B is preferably a resin having a melt flow rate of 5 g / 10 min to 40 g / 10 min. In the present invention, the measurement conditions for the melt flow rate of resin A are as follows: cylinder temperature 330 ° C., 5 kg load, orifice diameter 2.095 mm, and orifice length 8 mm. The measurement conditions for the melt flow rate of fluororesin are as follows: cylinder temperature 330 ° C., 5 kg load, orifice diameter 2.095 mm, orifice length 8 mm.

  Moreover, it is preferable that the compatibilizer which consists of a resin group which has maleic anhydride or a glycidyl group is mixed with the resin composition of this invention. Thereby, the dispersibility of the resin B with respect to the resin A becomes better, and the extrusion moldability can be further improved. In addition, the adhesion between the resin composition and the other resin is improved (for example, the adhesion between the extrusion coating layer made of the resin composition and the other coating layer is improved), the heat resistance of the insulating coating, Contributes to improved mechanical strength.

(Production method of resin composition)
Next, the manufacturing method of the resin composition which concerns on this invention is demonstrated. The method for producing a resin composition according to the present invention is roughly divided into a kneading step of kneading resin A and resin B to form a polymer alloy and an extrusion step of discharging the polymer alloy from an extrusion die.

  FIG. 3 is a schematic view showing an example of an extruder used for producing the resin composition according to the present invention. As shown in FIG. 3, the extruder 30 includes a screw 32 (screw shaft 321 and screw blade 322) for kneading the material in a cylinder 31. A hopper 33 for supplying the material to be supplied to the cylinder 31 is disposed, and an extrusion head 34 including an extrusion die 35 for extruding the material is disposed downstream of the cylinder 31.

  Resin A and resin B having a predetermined mixing ratio are put into hopper 33 and supplied to cylinder 31. At this time, it is preferable to add a compatibilizing agent comprising a resin group having maleic anhydride or a glycidyl group. Alternatively, a material that has been separately preliminarily kneaded using a kneader may be charged into the hopper 33. By performing preliminary kneading, the mixed state of resin A and resin B (dispersed state of resin B) can be improved.

  As described above, the mixing ratio of the resin A and the resin B in the polymer alloy is preferably “60/40 ≦ (resin A) / (resin B) ≦ 80/20” by mass ratio. When the mass part ratio between the resin A and the resin B is “80/20 <(resin A) / (resin B)”, the resin B is too small and the effect of reducing the relative dielectric constant becomes insufficient. On the other hand, when the mass part ratio between the resin A and the resin B is “(resin A) / (resin B) <60/40”, it becomes difficult to control the sea-island structure, and the extrudability of the resin composition is kept good. I can't.

  In the kneading step, the resin A and the resin B are kneaded by the rotation of the screw 32 in the cylinder 31 to form a polymer alloy. At this time, the kneading temperature is preferably 300 ° C. or higher and 350 ° C. or lower. Further, the shear rate is controlled so that sufficient shear stress is applied to the mixed resin.

FIG. 4 is a schematic view showing a cylinder cross section of the extruder shown in FIG. A flight screw as shown in FIG. 4 will be described as an example. When the tip clearance between the cylinder 31 and the screw 32 is c [unit m] and the peripheral speed at the tip of the screw 32 is v [unit m / s], the shear rate is given by v / c [unit s ⁻¹ ]. . In order to obtain a desirable sea-island structure, the shear rate is preferably “v / c ≧ 1200 s ⁻¹ ”. If the shear rate is insufficient, the shear stress applied to the mixed resin (especially resin B) becomes insufficient, and the equivalent circular average diameter of the island by the resin B exceeds 10 μm.

  The sea-island structure in the polymer alloy in the molten state is not in a stable state, and when it is held for a long time in an environment where no shear stress is applied, the islands of the resin B tend to coalesce and the dispersed state tends to deteriorate. For this reason, in the extrusion process, it is desirable to make the residence time of the polymer alloy (the period from the exit from the cylinder 31 to the passage through the extrusion molding die 35) as short as possible, and preferably within at least 5 minutes.

If the residence time without application of shear stress exceeds 5 minutes, the equivalent circular average diameter of the island by resin B tends to exceed 10 μm. As a method for shortening the residence time, for example, a method of narrowing the flow path of the polymer alloy in the extrusion head 34 (reducing the volume of the polymer alloy in the extrusion head 34) can be mentioned. The residence time in the extrusion head 34 is controlled by “(flow path volume in the extrusion head 34 [cm ³ ]) / (extrusion speed [cm ³ / s])”. The extrusion speed can be controlled by, for example, the screw speed [rpm], the pitch of the screw blades, the supply speed of the mixed resin [cm ³ / s], and the like.

  The polymer alloy that has passed through the extrusion die 35 is preferably immediately cooled to a temperature below the melting point so that the sea-island structure is fixed. For example, it is possible to cool the extruded material with water immediately after the polymer alloy has passed through the extrusion die 35.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example, this invention is not limited to these.

(Preparation of resin composition)
The resin composition was produced using the single screw extruder as shown in FIG. A mixture of Resin A and Resin B was put into a hopper of a single screw extruder and kneaded to form a polymer alloy, and a string-like resin composition was extruded from an extrusion die of an extrusion head. The string-shaped resin composition was cooled in a water tank immediately after being extruded, and then cut with a strand cutter to obtain cylindrical resin composition pellets (diameter: about 3 mm, length: about 5 mm).

  Resin compositions of Examples 1 to 8 and Comparative Examples 1 to 5 were prepared by variously changing the type and mixing ratio of the resin B to be mixed, the shear rate during kneading, and the residence time in the extrusion head. As the resin A, polyphenylene sulfide (PPS, Toray Industries Inc., A670T05, MFR = 10 g / 10 min) and (PPS, Toray Industries Inc., A900, MFR = 22 g / 10 min) having different melt flow rates were used. . As the resin B, a tetrafluoroethylene / hexafluoropropylene copolymer (FEP, Daikin Industries, Ltd., Neoflon (registered trademark)) having different melt flow rates (MFR = 1 to 40 g / 10 min) was used. As the compatibilizer, maleic acid-modified polyethylene (Mitsui Chemicals, Tuffmer (registered trademark) MH7020) was used. The shear rate during kneading was controlled by adjusting the number of rotations of the screw. The residence time in the extrusion head was controlled by adjusting the feed rate of the resin mixture.

  The compounding composition (mass part) and preparation conditions of the produced resin compositions of Examples 1-8 are shown in Tables 1-2, and the compounding composition (mass part) and preparation conditions of the resin compositions of Comparative Examples 1-5 are shown 3 shows.

  The following measurements and tests were performed on the resin compositions (Examples 1 to 8 and Comparative Examples 1 to 5) produced as described above.

(1) Measurement of relative dielectric constant As described above, as a means for increasing the partial discharge start voltage, there is a method using a resin having a low relative dielectric constant. Therefore, the relative dielectric constant of the produced resin composition was measured. The obtained resin composition pellets were molded into a sheet (600 mm × 600 mm × 1 mm) by injection molding, and the relative dielectric constant was measured using this sheet. LCR meter (Agilent Technology Co., E4980A) was used for the measurement. Measurement conditions were: Frequency: 1 kHz, Main electrode diameter: 37 mm, Guard electrode inner diameter: 39 mm, Guard electrode outer diameter: 50 mm, Measurement temperature : Room temperature. The results are shown in Tables 1-3. A relative dielectric constant of 3.20 or less was judged as “pass”.

(2) Microstructural observation (measurement of equivalent circular average diameter of island in sea-island structure and measurement of height difference of surface irregularities)
In order to satisfy all of the various characteristics (high heat resistance, high partial discharge starting voltage, good extrusion moldability) required for the extrusion coating layer of the insulated wire, the resin composition must have at least the predetermined sea-island structure (resin A It is desirable to have a sea portion and resin B to form an island portion having an equivalent circular average diameter of 10 μm or less. Therefore, the cross section of the pellet was observed with a scanning electron microscope (SEM), the area of each island was obtained by image analysis, and the average diameter of the equivalent circle was calculated. The results are shown in Tables 1-3.

  Similarly, the structure of the pellet surface was observed using SEM, and the difference (level difference) between the valleys and peaks of the surface irregularities was measured. Those having a height difference of 10 μm or less were judged as “pass”, and those over 10 μm were judged as “fail”. The results are shown in Tables 1-3.

(3) Rapid extension test (adhesion evaluation)
Using an extruder, the resin composition (Examples 1-8 and Comparative Examples 1-5) is extrusion coated on the outer layer of the conductor (copper wire, outer diameter 1.25 mm), and the insulated wire as shown in FIG. Was made. The adhesion between the conductor and the extrusion coating layer was evaluated by carrying out a rapid extension test based on JIS C3003. As a result of the rapid extension test, an extruding layer with a floating (peeling) length of 2 mm or less from the breaking point was evaluated as “pass”. The results are shown in Tables 1-3.

  As shown in Tables 1 and 2, in Examples 1 to 8, the mixing ratio of the resin A and the resin B is “60/40 ≦ (resin A) / (resin B) ≦ 80/20” by mass part ratio. It was confirmed that a sea-island structure was formed in which islands made of resin B having an equivalent circular average diameter of 10 μm or less were dispersed. And it was demonstrated that the resin composition of Examples 1-8 which has such a structure has a low relative dielectric constant, good adhesion, and good extrudability (small surface irregularities).

  More specifically, from Examples 1 to 3, when the mixing ratio of the resin B increased, the relative permittivity decreased, and the equivalent circle average diameter and surface irregularities of the island tended to increase. . In addition, it was confirmed from Example 8 that the equivalent circular average diameter of the island is reduced by adding a compatibilizing agent, and the extrusion moldability is improved (surface irregularities are reduced).

  On the other hand, as shown in Table 3, Comparative Example 1 in which the MFR of the mixed resin B was smaller than that of the present invention had a large average island diameter in the sea-island structure and was inferior in extrusion moldability (surface irregularities were It was big). This was thought to be because the islands were easy to reunite after the kneading step due to the small MFR of resin B.

  In Comparative Example 2 in which the mixing ratio of the resin B is smaller than that of the present invention, the effect of reducing the relative dielectric constant was insufficient. Further, in Comparative Example 3 in which the mixing ratio of the resin B was larger than that of the present invention, the equivalent circle average diameter of the island in the sea-island structure was large, and the extrusion moldability was inferior (surface irregularities were large).

  In Comparative Example 4 in which the shear rate in the kneading step was lower than that of the present invention, the average island diameter in the sea-island structure was large, and the extrusion moldability was inferior (surface irregularities were large). Moreover, the comparative example 5 whose residence time in an extrusion process is longer than prescription | regulation of this invention also had the large average diameter of the island in a sea-island structure, and was inferior in extrusion moldability (surface unevenness | corrugation was large).

  As described above, the resin composition according to the present invention can ensure good extrudability while realizing a relative dielectric constant lower than that of a conventional high heat-resistant extruded material. Moreover, by forming the extrusion coating layer using the resin composition of the present invention, it is possible to provide an insulated wire having a high partial discharge start voltage, good adhesion, and a good appearance without surface irregularities.

10, 20 ... insulated wires,
1 ... conductor, 2 ... insulation coating, 3 ... adhesive layer, 4 ... extrusion coating layer, 5 ... outermost layer
30 ... Extruder, 31 ... Cylinder,
32 ... Screw, screw shaft 321, screw blade 322,
33 ... Hopper, 34 ... Extrusion head, 35 ... Extrusion die.

Claims (5)

A resin composition comprising a polymer alloy,
The polymer alloy has a sea-island structure,
The sea component of the sea-island structure is polyphenylene sulfide (resin A), and the island component of the sea-island structure is a fluororesin (resin B) having an equivalent circular average diameter of 10 μm or less,
A resin composition, wherein a mixing ratio of the resin A and the resin B is “60/40 ≦ (resin A) / (resin B) ≦ 80/20” by mass ratio. The resin composition according to claim 1,
The resin A has a melt flow rate at 330 ° C. of 10 g / 10 min to 22 g / 10 min,
A resin composition, wherein the resin B has a melt flow rate at 330 ° C. of 5 g / 10 min or more and 40 g / 10 min or less. A method for producing a resin composition comprising a polymer alloy,
The polymer alloy has a sea-island structure, the sea component of the sea-island structure is polyphenylene sulfide (resin A), and the island component of the sea-island structure is a fluororesin (resin B) having an equivalent circular average diameter of 10 μm or less. ,
The manufacturing method includes a kneading step of kneading the resin A and the resin B having a predetermined mixing ratio by rotation of a screw in a cylinder of an extruder to form the polymer alloy,
An extrusion step of discharging the polymer alloy from an extrusion die provided downstream of the cylinder,
The predetermined mixing ratio is “60/40 ≦ (resin A) / (resin B) ≦ 80/20” by mass part ratio,
In the kneading step, when the clearance between the tip of the cylinder and the screw is c [unit m] and the peripheral speed of the tip of the screw is v [unit m / s], the resin A and the resin B And the shear rate applied to is "v / c ≥ 1200 s ^-1 "
The method for producing a resin composition, wherein the extruding step has a residence time of the polymer alloy of 5 minutes or less after leaving the cylinder and passing through the extrusion die. In the manufacturing method of the resin composition of Claim 3,
The resin A has a melt flow rate at 330 ° C. of 10 g / 10 min to 22 g / 10 min,
A method for producing a resin composition, wherein the resin B has a melt flow rate at 330 ° C. of 5 g / 10 min to 40 g / 10 min. An insulated wire having an insulation coating having an extrusion coating layer formed on a conductor,
An insulated wire, wherein the extrusion coating layer is made of the resin composition according to claim 1 or 2.

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