JP2014136738A - Resin composition for extrusion molding, method for manufacturing the same, and insulated electric cable using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for extrusion molding having a high partial discharge initiation voltage and exhibiting an excellent extrusion moldability enabling high-speed extrusion.SOLUTION: The provided resin composition for extrusion molding is a resin composition for extrusion molding which exhibits an apparent viscosity of 370 Pa s or above and 600 Pa s or below at a heating temperature of 320°C and at a shear rate of 243/s and which contains a polymer alloy including polyphenylene sulfide and a thermoplastic resin having a melting point higher than that of the polyphenylene sulfide in a state where the polymer alloy has a sea-island structure in which an island phase including the thermoplastic resin is dispersed within a sea phase including the polyphenylene sulfide and where the island phase has a fibrous shape of exhibiting, as the ratio of the long diameter thereof with respect to the short diameter thereof, an aspect ratio of at least 4.

Description

  The present invention relates to a resin composition for extrusion molding, a method for producing the same, and an insulated wire using the same.

  Insulated wires are used for coils in electrical equipment such as motors and transformers. Insulated wires generally have a single-layer or multiple-layer insulation coating (insulation layer) formed on the outer periphery of a conductor that has been formed into a cross-sectional shape (for example, round shape, rectangular shape, or stranded wire) that matches the application and shape. Has a structured. As a method for forming the insulating layer, there are a method in which an insulating paint in which a resin is dissolved in an organic solvent is applied and baked on a conductor, and a method in which a resin composition prepared in advance is extrusion coated on the conductor. In the extrusion coating method, an insulating layer is formed by extruding and coating a resin composition on the outer periphery of a conductor conveyed at a predetermined speed.

  In recent years, the coil used for an electric equipment tends to be miniaturized by the request | requirement of size reduction to an electric equipment. For example, in the process of processing an insulated wire into a coil, the insulated wire is wound at a high density around a small-diameter core under high tension. For this reason, the insulating layer is required to have mechanical characteristics (for example, adhesion) that can withstand severe stress.

  In addition, inverter control and higher voltage have been developed due to demands for higher efficiency and higher output for electric devices, and high voltage is applied to coils. For this reason, in the coil, the operating temperature tends to rise more than before, and high heat resistance is required for the insulating layer.

  In addition, in an insulated wire, a high partial discharge starting voltage is required for the insulating layer in order to prevent deterioration and damage of the insulating layer due to partial discharge. In order to improve the partial discharge start voltage of the insulating layer, there is a method of using a resin having a low relative dielectric constant as a resin constituting the insulating layer.

  As a resin excellent in mechanical properties, heat resistance and partial discharge start voltage, a resin composition in which polyphenylene sulfide (hereinafter also referred to as PPS) and polyamide (hereinafter also referred to as PPA) are mixed has been proposed (for example, patents). Reference 1). PPS has excellent heat resistance, mechanical characteristics, and partial discharge resistance, but has low melt tension, so-called melt tension, and poor extrusion moldability. For this reason, when PPS is pushed out on the outer periphery of the conveyed conductor, the pushed PPS is pulled and torn by the conveyance of the conductor. In this regard, in Patent Document 1, by adding PPA that reinforces the melt tension, the melt tension of PPS is improved and the extrusion moldability is improved. However, since PPA has a higher relative dielectric constant than PPS and may reduce the partial discharge start voltage of the resin composition, the amount of addition thereof is limited.

JP 2011-210520 A

  By the way, the cost reduction is requested | required also by the insulated wire which comprises the coil integrated in these by the request | requirement of cost reduction to a motor vehicle or household appliances. In order to manufacture an insulated wire at low cost, for example, it is conceivable to improve the production rate of the insulated wire by improving the speed (extrusion speed) of extruding the resin composition on the outer circumference of the conveyed conductor.

  However, since the resin composition shown in Patent Document 1 has insufficient extrusion moldability, the upper limit of the extrusion speed is 15 m / min, and it is difficult to further improve the production speed by increasing the extrusion speed. It was. When the extrusion speed is set to 20 m / min, for example, the extruded resin composition is pulled and torn (breaks) by the conveyance of the conductor, so that it is difficult to stably form the insulating layer. Since the force with which the resin composition is pulled increases corresponding to the magnitude of the extrusion speed, the resin composition breaks significantly as the extrusion speed is increased.

  On the other hand, in order to improve the extrusion moldability of the resin composition, it is conceivable to increase the content of PPA that reinforces the melt tension. However, PPA has a higher relative dielectric constant than PPS, and is a part of the resin composition. There is a risk of lowering the discharge start voltage.

  Moreover, in order to suppress breakage of the resin composition at the time of high-speed extrusion, it may be possible to adjust the heating temperature to a high temperature to lower the viscosity of the resin composition. By flowing, the thickness of the insulating layer formed becomes non-uniform, and the cross-sectional shape of the insulating layer may become unstable. In other words, simply adjusting the viscosity of the resin composition by the heating temperature cannot fundamentally improve the extrusion moldability of the resin composition, and it is difficult to increase the extrusion speed and increase the production speed. ing.

  As described above, in the resin composition shown in Patent Document 1, it is difficult to achieve both a high partial discharge start voltage and excellent extrusion moldability capable of high-speed extrusion.

  The present invention has been made in view of the above problems, and its object is to provide a resin composition for extrusion molding having a high partial discharge start voltage and exhibiting excellent extrudability capable of high-speed extrusion, and The object is to provide an insulated wire which is provided with an insulating layer using, and is manufactured at low cost.

According to a first aspect of the invention,
An extrusion molding resin composition comprising a polymer alloy containing polyphenylene sulfide and a thermoplastic resin having a melting point higher than that of the polyphenylene sulfide, wherein the polymer alloy is contained in the thermoplastic phase in the sea phase containing the polyphenylene sulfide. The island phase has a fiber shape with an aspect ratio of 4 or more as a ratio of the length of the major axis to the minor axis, and has a heating temperature of 320. An extrusion molding resin composition having an apparent viscosity of 370 Pa · s to 600 Pa · s at a shear rate of 243 / s at ° C is provided.

According to a second aspect of the invention,
The island phase is provided with the resin composition for extrusion molding according to the first aspect, in which an area of a cross section cut in a minor axis direction is 10 μm ² or less.

According to a third aspect of the invention,
There is provided the resin composition for extrusion molding according to the first or second aspect, wherein the thermoplastic resin is a polyamide having a melting point of 5 ° C. or higher and 350 ° C. or lower than the melting point of the polyphenylene sulfide.

According to a fourth aspect of the invention,
The extrusion molding resin composition according to any one of the first to third aspects, containing 1 to 20 parts by mass of the thermoplastic resin with respect to 100 parts by mass in total of the polyphenylene sulfide and the thermoplastic resin. Things are provided.

According to a fifth aspect of the present invention,
A method for producing an extrusion molding resin composition comprising a polymer alloy containing polyphenylene sulfide and a thermoplastic resin having a melting point higher than that of the polyphenylene sulfide, which is 5000 while melting the polyphenylene sulfide and the thermoplastic resin. A kneading step of kneading at a shear rate of not less than / s and not more than 1000000 / s to form the polymer alloy, and a cooling step of rapidly cooling the polymer alloy, wherein the polymer alloy is contained in the sea phase containing the polyphenylene sulfide. The island phase including the island phase containing the thermoplastic resin is dispersed, and the island phase has a fiber shape having an aspect ratio of 4 or more as a ratio of the length of the major axis to the minor axis. The apparent viscosity at a shear rate of 243 / s at a heating temperature of 320 ° C. is 37. Extrusion molding resin composition of the fifth aspect there is provided is less than Pa · s or more 600 Pa · s.

According to a sixth aspect of the present invention,
An insulated wire provided with an insulating layer made of the resin composition for extrusion molding according to the first to fourth aspects on the outer periphery of a conductor is provided.

  According to the present invention, it is possible to provide an extrusion resin composition having a high partial discharge start voltage and exhibiting excellent extrudability capable of high-speed extrusion, and an insulated wire manufactured at low cost using the same. Can do.

It is a figure which shows the cross section of the insulated wire which concerns on one Embodiment of this invention.

<Knowledge obtained by the present inventors>
Prior to the description of an embodiment of the present invention, the knowledge obtained by the present inventor will be described.

As described above, as a resin excellent in mechanical properties, heat resistance, and partial discharge start voltage, there is a resin composition (hereinafter, also referred to as polymer alloy) in which polyphenylene sulfide (PPS) and polyamide (PPA) are mixed. This polymer alloy is obtained by kneading two kinds of polymers, and has a sea-island structure in which the island phase of PPA is dispersed in the sea phase of PPS. By having this sea-island structure, the polymer alloy can obtain heat resistance derived from PPS, mechanical characteristics and partial discharge start voltage, and melt tension (extrudability) derived from PPA.
However, this polymer alloy still has a low melt tension and insufficient extrusion moldability. Therefore, it is difficult to obtain an extrusion moldability capable of high-speed extrusion, and it is difficult to increase the extrusion speed. Moreover, it is difficult to improve the extrusion moldability by increasing the PPA content in view of the balance with the partial discharge start voltage, and the addition amount is limited. That is, in polymer alloys, it is difficult to achieve both an extrudability capable of high-speed extrusion and a high partial discharge start voltage.

  The present inventor has intensively studied the phase structure (morphology) of a polymer alloy in order to achieve both the partial discharge start voltage and the extrusion moldability. As a result, when the island phase in the sea-island structure is made into a fiber shape having a predetermined aspect ratio, the increase in the dielectric constant is suppressed by minimizing the amount of PPA added to the main component PPS. However, it has been found that the extrusion moldability can be improved.

  In addition, in the sea-island structure of polymer alloy, in order to make the island phase into a fiber shape, it is necessary not only to knead two polymers at a predetermined shear rate but also to rapidly cool the polymer alloy obtained by kneading. I found it. The polymer alloy immediately after being kneaded is in a molten state at a high temperature, and when left at a high temperature, the island phases dispersed in the sea phase reaggregate, and the sea-island structure changes. That is, the sea-island structure can be stabilized by rapidly cooling the polymer alloy whose sea-island structure is likely to change in the molten state. The present invention has been made based on these findings.

<One Embodiment of the Present Invention>
Hereinafter, an embodiment of the present invention will be described.

(1) Resin composition for extrusion The resin composition for extrusion according to one embodiment of the present invention is a resin composition comprising polyphenylene sulfide (PPS) and a thermoplastic resin having a melting point higher than that of PPS. A polymer alloy obtained by kneading at a predetermined shear rate is included. This polymer alloy has a predetermined sea-island structure and has a predetermined apparent viscosity.
That is, the resin composition for extrusion molding according to the present embodiment includes a polymer alloy containing polyphenylene sulfide (PPS) and a thermoplastic resin having a melting point higher than that of PPS, and the polymer alloy is contained in a sea phase containing PPS. The island phase including the island phase including the thermoplastic resin is dispersed, and the island phase has a fiber shape having an aspect ratio of 4 or more as a ratio of the length of the major axis to the minor axis. The apparent viscosity at a shear rate of 243 / s at a temperature of 320 ° C. is 370 Pa · s or more and 600 Pa · s or less.

  The polymer alloy has a sea-island structure in which an island phase containing a thermoplastic resin is dispersed in a sea phase containing polyphenylene sulfide (PPS). PPS constitutes a sea phase (continuous phase) and includes an island phase (dispersed phase) containing a thermoplastic resin. PPS is a crystalline thermoplastic resin, has excellent mechanical properties and heat resistance, and exhibits a high partial discharge start voltage. However, PPS itself has a low melt tension and is inferior in extrusion moldability. On the other hand, the thermoplastic resin constitutes an island phase dispersed in the sea phase containing PPS. The thermoplastic resin has a melting point higher than that of PPS, and imparts melt tension to PPS constituting the sea phase by being dispersed in the sea phase as an island phase. However, the thermoplastic resin has a higher relative dielectric constant than PPS, and may increase the relative dielectric constant of the polymer alloy and lower the partial discharge start voltage.

  In the present embodiment, the polymer alloy has a predetermined sea-island structure. That is, the island phase in the sea-island structure has a predetermined fiber shape, and the aspect ratio as a ratio of the length of the major axis to the minor axis is 4 or more. The fiber shape has a major axis and a minor axis having different lengths, and shows, for example, a shape elongated like a rod or needle. The sea-island structure having such an island phase has the same structure as a so-called fiber-reinforced resin. With this structure, when the polymer alloy is in a molten state, the elongated island phase increases the melt tension, thereby improving the extrudability of the polymer alloy and increasing the extrusion speed. Moreover, when it becomes resin moldings, such as an insulating layer, the outstanding mechanical characteristic is shown. In addition, since the polymer alloy has a predetermined sea-island structure, the island phase can be finely dispersed in the sea phase even when the amount of the thermoplastic resin added is small. If the island phase does not have a fiber shape, that is, if the aspect ratio is lower than 4, it becomes difficult to increase the melt tension and improve the extrusion moldability. Further, the insulating layer formed by extrusion cannot obtain mechanical properties such as tensile strength and elongation.

  Here, the aspect ratio indicates the ratio (b / a) of the length of the major axis b to the minor axis a in the fiber-shaped island phase. In this embodiment, the ratio of the dispersed island phases (b / a) ) Average value. The upper limit of the aspect ratio is not particularly limited, but is preferably 4 or more and 1000 or less.

  The polymer alloy has a predetermined sea-island structure, so that the apparent viscosity is 370 Pa · s or more and 600 Pa · s or less. The apparent viscosity indicates the viscosity when measured at a shear rate of 243 / s at a heating temperature of 320 ° C. When the apparent viscosity is less than 370 Pa · s, since the viscosity is too low, it flows when extruded onto the conductor, and the thickness of the formed insulating layer becomes non-uniform. On the other hand, if it exceeds 600 Pa · s, the torque increases due to the shear stress during extrusion, and it becomes difficult to maintain a sufficient and stable discharge amount.

  As described above, when the polymer alloy is in a high-temperature molten state immediately after kneading, the island phase may aggregate and the sea-island structure may change. For this reason, in this embodiment, it is preferable that the polymer alloy is cooled immediately after kneading. That is, the polymer alloy is preferably obtained by kneading and rapidly cooling polyphenylene sulfide and a thermoplastic resin. As a result, the polymer alloy has a stable sea-island structure in which changes in the phase structure are suppressed.

In the polymer alloy, the island phase in the sea-island structure preferably has an area of a section (hereinafter also referred to as a transverse section) cut in the minor axis direction of 10 μm ² or less. Here, the area of the cross section indicates an average value of the areas of the cross sections in the dispersed island phases. If the area of the cross section exceeds 10 μm ² , the island phase becomes large, so that the surface of the formed insulating layer has minute irregularities, and the extrusion appearance may be deteriorated.

  The thermoplastic resin is not particularly limited as long as it is a thermoplastic resin having a melting point higher than that of PPS. Since such a thermoplastic resin exhibits a higher melt tension than PPS when it is heated and melted together with PPS and kneaded, it can impart a melt tension to the polymer alloy. Such a resin is preferably a resin having a melting point of 5 ° C. or higher and 350 ° C. or lower than the melting point of PPS. For example, polyamide, aromatic polyether ketone, thermoplastic polyimide, thermoplastic polyetherimide, perfluoroalkoxy A fluororesin such as a fluororesin (PFA) can be used. According to these resins, the melt tension of the polymer alloy can be further increased and the extrusion moldability can be improved.

  Examples of the polyamide include nylon 46, which is an aliphatic polyamide, nylon 6T, which is an aromatic polyamide (copolycondensation polymer of hexamethylenediamine and terephthalic acid), and nylon 6I (copolycondensation of hexamethylenediamine and isophthalic acid). Nylon 9T (copolycondensation polymer of nonanediamine and terephthalic acid), nylon M-5T (copolycondensation polymer of methylpentadiamine and terephthalic acid), nylon 6T / 66 (copolymerization of nylon 6T and nylon 66) Polymer), nylon 6T / 6I (copolymer of nylon 6T and nylon 6I), nylon 6T / 6I / 66 (copolymer of nylon 6T, nylon 6I and nylon 66), nylon 6T / M-5T ( Nylon 6T and nylon M-5T copolymer), nylon 6T / 6 (nylon 6T and nylon Copolymers of emissions 6), and the like. These may be used alone or in combination.

  Further, nylon 6 (ε-caprolactam polycondensate), nylon 66 (co-condensation polymer of hexamethylenediamine and adipic acid) and the like may be further mixed with the listed polyamide as a main component. In this case, for example, when a polyamide is thermally analyzed using a differential scanning calorimeter (DSC) at a temperature increase rate of 10 ° C./min, the amount of nylon 6 or nylon 66 is in an amount that does not lower the main peak of the melting point. A low melting point polyamide or the like may be mixed to adjust the viscosity and mechanical properties.

  Examples of the aromatic polyether ketone include polyether ether ketone (PEEK), polyether ketone ketone, and polyether ketone. These may be used alone or in combination.

  Examples of the thermoplastic polyimide and polyetherimide include Aurum (registered trademark) manufactured by Mitsui Chemicals, Ultem (registered trademark) manufactured by sabic, and the like. These may be used alone or in combination.

  Examples of the fluororesin include perfluoroalkoxy fluororesin (PFA), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), and ethylene / tetrafluoroethylene copolymer (ETFE). These may be used alone or in combination.

  In the polymer alloy sea-island structure, the ratio of the island phase to the sea phase corresponds to the ratio of the addition amount of PPS and thermoplastic resin (part by mass ratio). In this embodiment, since the island phase is formed in a predetermined shape and finely dispersed in the sea phase, the amount of thermoplastic resin that is an additive component can be suppressed to a low level. The mass part ratio is not particularly limited, but if the addition amount of the thermoplastic resin is too small, there is a possibility that sufficient melt tension cannot be obtained in the polymer alloy. Moreover, when there is too much addition amount of a thermoplastic resin, in polyamide, for example, the influence of the polar group in a molecular structure will increase relatively, and there exists a possibility of reducing the partial discharge start voltage of a polymer alloy. For this reason, it is preferable that mass part ratio (B / A) of content (A) of PPS and content (B) of a thermoplastic resin is 1/99 or more and 20/80 or less. That is, it is preferable to add 1 to 20 parts by mass of thermoplastic resin and 80 to 99 parts by mass of PPS with respect to 100 parts by mass in total of PPS and thermoplastic resin.

  According to the resin composition for extrusion molding of the present embodiment, since it contains a polymer alloy having a predetermined sea-island structure and has a predetermined melt tension in a molten state, it is excellent in extrusion moldability and suitable for high-speed extrusion. Moreover, in order to suppress the raise of a dielectric constant by minimizing content of the thermoplastic resin added to PPS, it has a high partial discharge start voltage. Moreover, when it becomes resin moldings, such as an insulating layer, it is excellent in a mechanical characteristic.

(2) Manufacturing method of resin composition for extrusion molding Next, the manufacturing method of the above-mentioned resin composition for extrusion molding is demonstrated.

In the present embodiment, a resin composition containing PPS and a thermoplastic resin is kneaded at a predetermined shear rate to form a polymer alloy having a predetermined sea-island structure, and then rapidly cooling the formed polymer alloy, An extrusion molding resin composition containing a polymer alloy in which a change in phase structure (hereinafter also referred to as morphology) is suppressed is obtained.
That is, the manufacturing method of this embodiment is a manufacturing method of an extrusion molding resin composition containing a polymer alloy containing polyphenylene sulfide (PPS) and a thermoplastic resin having a melting point higher than that of PPS. A kneading step of forming a polymer alloy by kneading at a shear rate of 5000 / s to 1000000 / s while melting the plastic resin, and a cooling step of rapidly cooling the polymer alloy.

  First, PPS as a main component and a thermoplastic resin as an additive component are mixed to form a mixture. At this time, the ratio (part by mass) of the addition amount of PPS and the thermoplastic resin is appropriately adjusted so that the partial discharge start voltage of the polymer alloy does not decrease too much. Preferably, 1 part by mass or more and 20 parts by mass or less of the thermoplastic resin is added to 100 parts by mass in total of the PPS and the thermoplastic resin.

  Subsequently, as the kneading step, the obtained mixture is kneaded at a predetermined shear rate while heating. By kneading, a polymer alloy having a sea-island structure in which an island phase containing a thermoplastic resin is dispersed in a sea phase containing PPS is formed. In the sea-island structure of polymer alloy, the island phase has a fiber shape with an aspect ratio of 4 or more as a ratio of the length of the major axis to the minor axis. Further, the polymer alloy has a predetermined sea-island structure and has an apparent viscosity of 370 Pa · s to 600 Pa · s.

In the kneading process, if the shear rate is low, it is difficult to finely disperse the island phase in the sea phase, and the size of the dispersed island phase increases. Moreover, it is difficult to make the island phase into a fiber shape, and the aspect ratio of the island phase is smaller than 4. On the other hand, when the shear rate is high, the molecular weight of the polymer alloy is lowered, and the mechanical properties may be lowered. In addition, when the shearing force is low, the area of the cross section cut in the minor axis direction of the island phase may be larger than 10 μm ² . Therefore, in the kneading step, the shear rate is preferably 5000 / s or more and 1000000 / s or less. The shear rate γ (s−1) is defined as “γ = v / t” from the clearance t (mm) between the cylinder and the screw in the twin-screw extruder and the rotational speed v (mm / s) of the screw. .

  In the kneading step, the temperature at which the mixture is heated is not particularly limited as long as it is a temperature at which the mixture can be melted. That is, the heating temperature is preferably higher than the melting point of the PSS and the thermoplastic resin used.

  Moreover, as a kneading apparatus used in the kneading step, general-purpose devices such as a kneader, a Banbury mixer, a roll, a twin screw extruder can be used, but a twin screw extruder is preferable.

  Then, the obtained polymer alloy is cooled as a cooling process. The obtained polymer alloy is in a molten state, and when left for a long time without being cooled, the finely dispersed island phases reagglomerate and the phase structure changes. The fiber-shaped island phase re-aggregates with time and deposition increases, so that the aspect ratio becomes smaller and becomes a substantially spherical shape. Therefore, in this embodiment, the obtained polymer alloy is rapidly cooled to suppress a change in morphology in the polymer alloy. The rapid cooling is preferably performed immediately after the polymer alloy is formed (immediately after the kneading step). However, in the case of air cooling, it is preferably performed at least within 20 seconds after the kneading step, and in the case of water cooling, at least after the kneading step. It is preferable to carry out within 1 minute. The cooling step is performed at a temperature lower than the melting point of PPS and the thermoplastic resin.

  The resin composition for extrusion molding containing a polymer alloy is manufactured by the above. This polymer alloy has a morphological change suppressed, and has a sea-island structure in which an island phase containing a thermoplastic resin is dispersed in a sea phase containing PPS. The island phase has a length of a major axis with respect to a minor axis. The fiber has an aspect ratio of 4 or more. The apparent viscosity is 370 Pa · s or more and 600 Pa · s or less.

(3) Insulated wire Next, an insulated wire including an insulating layer made of the above-described resin composition for extrusion molding will be described with reference to FIG. FIG. 1 is a diagram showing a cross section of an insulated wire according to an embodiment of the present invention.

  As shown in FIG. 1, the insulated wire 1 of the present embodiment includes a conductor 10 and a single-layer insulating layer 11 formed on the outer periphery of the conductor 10, and the insulating layer 11 is an extrusion molding resin. It consists of a composition.

  As the conductor 10, in addition to a copper wire made of low-oxygen copper, oxygen-free copper or the like, a copper alloy wire, other metal wires such as silver are used. Although FIG. 1 shows a case where the conductor 10 has a round cross section, the present invention is not limited to this, and may be, for example, rectangular (including those having four curved corners). Moreover, the conductor diameter of the conductor 10 is not specifically limited, The optimal numerical value is suitably selected according to a use.

  The insulating layer 11 is made of an extrusion molding resin composition. The insulating layer 11 is formed by extrusion coating the resin composition for extrusion molding on the outer periphery of the conductor 10 so as to have a predetermined thickness. The thickness of the insulating layer 11 is not particularly limited, and an optimal value is appropriately selected according to the application.

  The insulating layer 11 is formed by extruding a resin composition for extrusion molding on the outer periphery of the conductor 10 to be conveyed. Since the resin composition for extrusion molding of the present embodiment has extrusion moldability capable of high-speed extrusion, it can be formed, for example, at an extrusion speed of 2 m / min to 200 m / min. The extrusion molding resin composition extruded onto the outer periphery of the conductor 10 is cured by being rapidly cooled by air cooling or water cooling, and becomes the insulating layer 11 having a predetermined morphology.

  In addition, when extruding the resin composition for extrusion onto the outer periphery of the conductor 10, it is melted by heating and extruded, but the island phase is re-aggregated by heating at this time, and the insulating layer 11 having a predetermined sea-island structure is formed. May not be obtained. For this reason, during heat melting, it is preferable to extrude while kneading at a shear rate of 400 / s or more. However, if the shear rate is too high, the dimensional accuracy of the insulating layer 11 may become unstable.

  According to the insulated wire 1 of the present embodiment, the insulating layer 11 is made of an extrusion molding resin composition containing a polymer alloy having a predetermined sea-island structure. For this reason, the insulated wire 1 is excellent in mechanical characteristics and partial discharge start voltage, and has a good extrusion appearance. Moreover, since the insulated wire 1 is manufactured by high-speed extrusion, it is inexpensive.

<Effects according to this embodiment>
According to the present embodiment, the following one or more effects are achieved.

  According to the resin composition for extrusion molding according to the present embodiment, the polymer alloy includes a polymer alloy, and the polymer alloy has a sea-island structure in which an island phase containing a thermoplastic resin is dispersed in a sea phase containing PPS. It has a fibrous shape with an aspect ratio of 4 or more as a ratio of the length of the major axis to the minor axis, and the apparent viscosity is 370 Pa · s or more and 600 Pa · s or less. Thereby, since it has a predetermined melt tension in a molten state, it is excellent in extrusion moldability even when high-speed extrusion is performed. In addition, since the increase in the dielectric constant can be suppressed by minimizing the content of the thermoplastic resin added to the PPS, it has a high partial discharge start voltage. That is, according to this embodiment, it is possible to achieve both the extrusion moldability when high-speed extrusion is performed and a high partial discharge start voltage.

  Further, according to the resin composition for extrusion molding of the present embodiment, when the polymer alloy has a predetermined sea-island structure and has a structure like a reinforced fiber resin, it becomes a resin molded body such as an insulating layer. Shows excellent mechanical properties.

The island phase preferably has an area of a cross section cut in the minor axis direction of 10 μm ² or less. Thereby, while disperse | distributing the island phase to a sea phase more finely, the shape of an island phase can be formed more fibrously. As a result, the extrusion moldability can be further improved.

  The thermoplastic resin is preferably a polyamide having a melting point of 5 ° C. or higher and 350 ° C. or lower than the melting point of PPS. Thereby, the melt tension in the molten state can be further improved, and the extrusion moldability can be improved. Moreover, the extrusion speed can be further increased.

  Moreover, it is preferable to contain a thermoplastic resin 1 mass part or more and 20 mass parts or less with respect to a total of 100 mass parts of PSS and a thermoplastic resin. Thereby, since content of the thermoplastic resin which raises the dielectric constant of a polymer alloy can be suppressed, it has a high partial discharge start voltage.

  According to the extrusion molding resin composition of the present embodiment, since the extrusion speed can be increased, the production speed of the insulated wire can be improved and the manufacturing cost of the insulated wire can be reduced. That is, an inexpensive insulated wire can be obtained.

<Other embodiments>
As mentioned above, although one Embodiment of this invention was described concretely, this invention is not limited to the above-mentioned embodiment, A various change is possible in the range which does not deviate from the summary.

  In the resin composition for extrusion molding, in order to improve the flexibility of the insulating layer to be formed, in addition to the polymer alloy described above, the polyolefin resin was modified with maleic anhydride or glycidyl methacrylate. A resin may be contained. Moreover, you may contain antioxidant, a copper damage inhibitor, a lubricant, a coloring agent, etc. as needed.

  Moreover, in the resin composition for extrusion molding, in order to increase the melt tension and improve the extrusion moldability, the thermoplastic resin contained in the polymer alloy may be crosslinked by silane crosslinking or the like.

  Moreover, in an insulated wire, you may provide separately the layer which provides lubricity and mechanical strength on the outer periphery of an insulating layer.

  Next, examples of the present invention will be described. In this example, a polymer alloy was prepared and an insulated wire was manufactured using the polymer alloy. And the prepared polymer alloy and the manufactured insulated wire were evaluated. These examples are examples of the polymer alloy and the insulated wire according to the present invention, and the present invention is not limited to these examples.

(1) Raw materials The materials used in the following examples and comparative examples are as follows.

Polyphenylene sulfide (PPS): “Torelina (registered trademark)” manufactured by Toray Industries, Inc.
(Viscosity at 330 ° C .; 1200 Pa · s, tensile strength: 65 MPa, melting point: 278 ° C.)
Polyamide (PPA): Kuraray "Genesta"
(Viscosity at 330 ° C .; 400 Pa · s, tensile strength: 145 MPa, melting point 306 ° C.)

(2) Preparation of Extrusion Resin Composition Next, an extrusion resin composition composed of a polymer alloy was prepared using the above-described raw materials. The preparation conditions are shown in Table 1 below.

In Examples 1 to 5, as shown in Table 1, the ratio (part by mass) of PPS and PPA was appropriately changed to prepare an extrusion molding resin composition made of polymer alloy. Specifically, PPS and PPA are charged into a twin-screw extruder at a predetermined ratio, and kneaded at a predetermined shear rate while controlling the screw rotation speed of the twin-screw extruder, so that the sea phase containing PPS. A polymer alloy having a sea-island structure in which island phases containing PPA were dispersed was prepared. At the time of kneading, the cylinder temperature of the twin screw extruder was set higher than the melting points of PPS and PPA to 380 ° C. or less in consideration of the decomposition temperature of PPS and PPA so that the polymer alloy was not deteriorated. Thereafter, the obtained polymer alloy was cooled immediately (within 3 seconds after kneading) so that reagglomeration of PPA did not occur, so that the polymer alloy was formed into pellets.
In Examples 1 to 5, the addition amount ratio (parts by mass) of PPS and PPA is 90:10 in Example 1, 95: 5 in Example 2, 98: 2 in Example 3, In Example 4, it was 90:20, and in Example 5, it was 99: 1. In Examples 1 to 5, the shear rate during kneading was set to 5000 / s.

  Comparative Example 1 was prepared in the same manner as Example 1 except that only PPS was used.

  Comparative Example 2 was prepared in the same manner as in Example 1 except that the shear rate during kneading was 1000 / s.

  Comparative Example 3 was prepared in the same manner as in Example 1 except that the shear rate during kneading was set to 1000000 / s.

(3) Production of insulated wire Next, an insulated wire was produced using the prepared polymer alloy. Specifically, the extrusion molding resin composition containing the polymer alloy obtained is extruded and coated on the outer periphery of a copper wire (outer diameter: 1.0 mm) as a conductor at a predetermined extrusion speed by an extruder. (Thickness 100 μm) was formed, and an insulated wire was manufactured. The temperature during extrusion coating was set to 300 ° C.

(4) Evaluation of resin composition for extrusion molding Next, the resin composition for extrusion molding comprising the obtained polymer alloy was evaluated by the following method.

(Morphology)
The cross section of the pellet was observed using a scanning electron microscope, and the aspect ratio of the island phase in the sea-island structure and the cross sectional area of the cross section perpendicular to the extrusion direction of the island phase (cross section cut in the minor axis direction) were obtained.

(Apparent viscosity)
About the resin composition for extrusion molding, the apparent viscosity on the measurement conditions of temperature 320 degreeC and shear rate 243 / s was measured using the capillary rheometer.

(Extrudability)
The evaluation of extrusion moldability was performed according to the following procedure. When extruding a resin composition for extrusion molding containing a polymer alloy onto a conductor to coat the surface, the outer diameter after forming the insulating layer is monitored by an outer diameter measuring instrument while checking the thickness of the insulating layer. The speed was gradually increased to determine the extrusion speed at which extrusion could not be performed, that is, the extrudable speed as the upper limit. In this example, the extrusion moldability of the polymer alloy was evaluated based on the extrudable speed.

(5) Evaluation of insulated wire Moreover, the following method evaluated the manufactured insulated wire.
(Tensile test)
The tensile test was performed according to the following procedure. The produced insulated wire is cut out, and the conductor is drawn out to produce a tube having only an insulating layer. Both ends of this tube were fixed to two clamps provided in the tensile tester and marked. At this time, the distance between the marked lines was 20 mm, and the tube was pulled at a pulling speed of 200 mm / min to obtain the tensile strength and elongation of the tube.

(Extruded appearance)
The extrusion appearance was evaluated by the following procedure. The surface of the insulating layer in the manufactured insulated wire was observed, and those having irregularities of 10 μm or more were regarded as unacceptable, and those less than 10 μm were accepted as “◯”.

(6) Evaluation Results As shown in Table 1, the polymer alloys of Examples 1 to 5 were confirmed to have a fiber shape in which the island phase had a predetermined aspect ratio in the sea-island structure. Moreover, it was confirmed that the cross-sectional area of the island phase is 10 μm ² or less. The polymer alloys of Examples 1 to 5 are suitable for high speed extrusion, and the upper limit of the extrusion speed is 50 m / min in Example 1, 41 m / min in Example 2, 35 m / min in Example 3, and In Example 4, it was 20 m / min, and in Example 5, it was 18 m / min, which was confirmed to be faster than the conventional 15 m / min.

  Moreover, the insulated wire of Examples 1-5 has predetermined | prescribed tensile strength and elongation, and it was confirmed that it is excellent in the mechanical characteristic. Moreover, the unevenness | corrugation of 10 micrometers or more was not confirmed on the surface of the insulating layer, but it was confirmed that the extrusion external appearance is favorable.

  Since the polymer of Comparative Example 1 is composed only of PPS, the upper limit of the extrusion speed is 15 m / min, and it was confirmed that the polymer was not suitable for high-speed extrusion. Thereby, it was confirmed that the production speed of an insulated wire was low and cost increased. Moreover, it was confirmed that the insulated wire of the comparative example 1 was inferior in tensile strength and elongation compared with Examples 1-5, and its mechanical characteristics were low.

Since the polymer alloy of Comparative Example 2 was kneaded at a low shear rate, the island phase aspect ratio was 2, the island phase cross-sectional area was as large as 530 μm ^2, and it was confirmed that the PPA dispersion was insufficient. It was done. Moreover, the polymer alloy of Comparative Example 2 has an upper limit of the extrusion speed of 15 m / min, and it was confirmed that it was not suitable for high-speed extrusion. Thereby, it was confirmed that the production speed of the insulated wire was low and the cost was increased as in Comparative Example 1. In Comparative Example 2, the dispersion of PPA was insufficient, and the effect of improving the extrusion moldability by PPA was not confirmed. Since the insulated wire of Comparative Example 2 had insufficient PPA dispersion in the polymer alloy, it was confirmed that the mechanical properties (tensile strength and elongation) of the insulating layer were lower than those of Comparative Example 1.

  The polymer alloy of Comparative Example 3 has a predetermined sea-island structure, and the upper limit value of the extrusion speed is 20 m / min, which was confirmed to be suitable for high-speed extrusion. Moreover, it was confirmed that the insulated wire of Comparative Example 3 has a good extrusion appearance. However, in the insulated wire of Comparative Example 3, since kneading was performed at a high shear rate, it was confirmed that the polymer alloy itself was deteriorated and the mechanical properties (elongation) of the formed insulating layer were lowered. For this reason, in the insulated wire of the comparative example 3, there is a concern that cracks may occur due to severe processing stress when processing into a coil.

  As described above, according to the resin composition for extrusion including a polymer alloy having a predetermined sea-island structure, the resin composition has a high partial discharge start voltage and has an extrusion moldability capable of high-speed extrusion.

1 Insulated wire 10 Conductor 11 Insulating layer

Claims (6)

A resin composition for extrusion molding comprising a polymer alloy containing polyphenylene sulfide and a thermoplastic resin having a melting point higher than that of the polyphenylene sulfide,
The polymer alloy is
The sea phase including the polyphenylene sulfide has a sea-island structure in which the island phase including the thermoplastic resin is dispersed, and the island phase has an aspect ratio of 4 or more as a ratio of the length of the major axis to the minor axis. Have a fiber shape that is
An apparent viscosity at a heating temperature of 320 ° C. at a shear rate of 243 / s is 370 Pa · s to 600 Pa · s. ^{2. The} resin composition for extrusion molding according to claim 1, wherein the island phase has an area of a cross section cut in a minor axis direction of 10 μm ² or less. 3. The resin composition for extrusion molding according to claim 1, wherein the thermoplastic resin is a polyamide having a melting point of 5 ° C. or higher and 350 ° C. or lower than the melting point of the polyphenylene sulfide. The resin for extrusion molding according to claim 1, wherein the thermoplastic resin is contained in an amount of 1 to 20 parts by mass with respect to a total of 100 parts by mass of the polyphenylene sulfide and the thermoplastic resin. Composition. A method for producing an extrusion molding resin composition comprising a polymer alloy containing polyphenylene sulfide and a thermoplastic resin having a melting point higher than that of the polyphenylene sulfide,
A kneading step of kneading the polyphenylene sulfide and the thermoplastic resin at a shear rate of 5,000 / s to 1,000,000 / s to form the polymer alloy;
A cooling step for rapidly cooling the polymer alloy,
The polymer alloy has a sea-island structure in which an island phase containing the thermoplastic resin is dispersed in a sea phase containing the polyphenylene sulfide, and the island phase has an aspect as a ratio of the length of the major axis to the minor axis. A resin composition for extrusion molding having a fiber shape with a ratio of 4 or more and an apparent viscosity at a shear rate of 243 / s at a heating temperature of 320 ° C. of 370 Pa · s to 600 Pa · s. Manufacturing method. An insulated wire comprising an insulating layer made of the resin composition for extrusion molding according to claim 1 on the outer periphery of a conductor.

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