Insulated wire

Abstract

To develop and provide an insulated wire having excellent flame retardancy, surface appearance and print quality.SOLUTION: An insulated wire 10 has a conductor 1 and an insulating layer 2 covering the conductor 1. The insulating layer 2 comprises a resin composition comprising (A) a polymer containing (A-1) an ethylenic copolymer with a melt flow rate (MFR) of 2[g / 10 min] or less and (A-2) and an ethylenic copolymer with a melt flow rate (MFR) of 9-100[g / 10 min], and (B) a flame retardant.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an insulated wire, and particularly to an insulated wire having excellent flame retardancy, surface appearance, and printability.

Background Art

[0002] Conventionally, an insulated wire is composed of a conductor and a covering insulator that covers the conductor, and various types are known (see, for example, Patent Document 1).

[0003] In addition, an insulated wire having excellent flame retardancy has a configuration in which a flame retardant is added to the resin composition of the covering material. However, the addition amount is large, and the flame retardant protrudes from the surface of the covering material, making it impossible to maintain the smoothness of the appearance. However, there was an advantage that the anchor effect was exhibited and the printability was excellent due to the rough appearance rather than the smooth appearance.

[0004] On the other hand, considering the above smoothness, when the addition amount of the flame retardant in the resin composition is reduced, the smoothness of the appearance can be maintained. However, since the flame retardancy and printability are inferior, it has been difficult to satisfy all these characteristics.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Therefore, an object of the present invention is to provide an insulated wire having excellent flame retardancy, surface appearance, and printability. Other objects and novel features will become apparent from the description of this specification and the accompanying drawings.

Means for Solving the Problems

[0007] Among the embodiments disclosed in the present application, the outline of typical ones will be briefly described as follows.

[0008] The insulated wire of the present invention is a wire having a conductor and an insulating layer covering the conductor, wherein the insulating layer is composed of a polymer containing (A) (A-1) an ethylene copolymer having a melt flow rate (MFR) of 2 [g / 10 min] or less and (A-2) an ethylene copolymer having a melt flow rate (MFR) of 9 to 100 [g / 10 min], and (B) a flame retardant. The (A) polymer contains 5 to 20% by mass of the (A-2) component and has an SP value of 8.73 or more, and the (B) flame retardant is contained in the range of 60 to 100 parts by mass with respect to 100 parts by mass of the (A) polymer.

Advantages of the Invention

[0009] According to the present invention, it is possible to provide an insulated wire excellent in flame retardancy, surface appearance, and printability.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0011] Hereinafter, the embodiments will be described in detail with reference to the drawings. In all the drawings for explaining the embodiments, members having the same function are denoted by the same reference numerals, and the repeated description thereof will be omitted. Further, in the following embodiments, the description of the same or similar parts will not be repeated in principle unless particularly necessary.

[0012] (Embodiment) As shown in FIG. 1, the insulated wire 10 according to the present embodiment is configured to have a conductor 1 and an insulating layer 2 covering the periphery of the conductor 1.

[0013] The conductor 1 can be used without particular limitation as long as it is a commonly used metal wire. For example, in addition to copper wires and copper alloy wires, aluminum wires, gold wires, silver wires, etc. can be used. Further, as the conductor 1, a metal wire with a metal plating such as tin or nickel applied around it may be used.

[0014] Also, as the conductor 1, a stranded wire formed by twisting a plurality of wire rods can be used, and further, a structure in which a plurality of stranded wires are twisted together may be employed. Fig. 1 shows an insulated electric wire exemplifying a structure in which 7 stranded wires are twisted together.

[0015] The insulating layer 2 is formed using the resin composition according to the present embodiment, which will be described in detail below. The thickness of the insulating layer 2 is not particularly limited, but is preferably 0.15 to 2 mm.

[0016] Hereinafter, the resin composition for forming the insulating layer 2 of the present embodiment will be described in detail. The resin composition according to the present embodiment comprises (A) a polymer and (B) a flame retardant, and (C) additives other than the flame retardant can be blended as necessary.

[0017] The (A) polymer used in the present embodiment comprises (A-1) an ethylene-based copolymer having a melt flow rate (MFR) of 2 [g / 10 min] or less and (A-2) an ethylene-based copolymer having a melt flow rate (MFR) of 9 to 100 [g / 10 min].

[0018] Here, the (A) polymer is a mixed polymer in which the (A-1) component is contained as a base polymer and the (A-2) component is mixed so as to contain 5 to 20% by mass. At this time, it is preferable that the (A-1) component, which is the base polymer, contains 70% by mass or more. By using such a mixed polymer, while ensuring the characteristics of the (A-1) component, which is generally excellent in wire extrusion properties, the (A-2) component with high fluidity is blended, thereby improving the surface appearance. At this time, if the blending amount of the (A-2) component is less than 5% by mass, the effect of improving the surface appearance will not be manifested, and if it exceeds 20% by mass, the surface appearance may become rough.

[0019] Incidentally, the melt flow rate (MFR) is one of the measures indicating the fluidity of a resin in a solution state, and is also referred to as the melt index (MI). The melt flow rate (MFR) in this specification is a value calculated by a melt flow rate test (MFR test) that measures the amount of resin extruded from the opening at the bottom of a container in 10 minutes under the load conditions of 190°C and 2.16 kg for the resin placed in a cylindrical extrusion plastometer.

[0020] Further, the polymer (A) is formed by mixing the above components (A-1) and (A-2), and the SP value (solubility parameter) of the mixed polymer is set to 8.73 or more. By setting the SP value of the polymer (A) to 8.73 or more, while the surface appearance is smooth, the compatibility with printing ink is enhanced, and the printability can be improved.

[0021] The SP value (solubility parameter) is a numerical value that serves as a measure of the compatibility of substances. The closer the SP values of the substances to be mixed are, the easier they are to be compatible. Solvents used for printing ink are generally highly polar solvents, and their SP values are estimated to be between 8 and 10. Therefore, by setting the SP value of the polymer (A) within the above range, the printability can be improved.

[0022] Incidentally, the SP value of the polymer (A) can be calculated by the following mathematical formula (1) based on the Fedors method. δ = [ΣE coh / ΣV] 1 / 2 ···(1) δ: SP value [-] E coh : Evaporation energy [cal / mol] V: Molar volume [cm 3 / mol]

[0023] Further, for the manifestation of flame retardancy, the ethylene-based copolymer blended as the polymer (A) is preferably an ethylene-ethyl acrylate copolymer (EEA) or an ethylene-vinyl acetate copolymer (EVA).

[0024] Furthermore, for the manifestation of flame retardancy, it is preferable to include chlorinated polyethylene (CPE) in the (A) polymer, and at this time, it is more preferable that the chlorine content in the (A) polymer is 1 to 5% by mass. If this chlorine content is less than 1% by mass, there is no effect due to the addition of CPE, and if it exceeds 5% by mass, there is a risk that the surface appearance of the coating material will become rough due to the dehydrochlorination of CPE during extrusion.

[0025] As the CPE used here, either amorphous or semi-crystalline CPE may be used, and one of these CPEs may be used alone, or two or more of them may be used in combination. In the examples described later, semi-crystalline CPE was used.

[0026] The (B) flame retardant used in this embodiment is not particularly limited as long as it is a known flame retardant compounded in insulated electric wires, and in this embodiment, the (B) flame retardant is contained in the range of 60 to 100 parts by mass with respect to 100 parts by mass of the (A) polymer. By setting such a formulation, sufficient flame retardancy can be ensured. If this content is less than 60 parts by mass, sufficient flame retardancy cannot be exhibited, and if it exceeds 100 parts by mass, there is a risk that the (B) flame retardant will protrude from the surface of the coating material and the surface appearance will become rough.

[0027] Here, examples of the flame retardant include halogen-based, phosphorus-based, antimony-based, metal hydroxides, etc., and one of these may be used alone, or two or more of them may be used in combination. Examples of the halogen-based flame retardant include bromine-based flame retardants, etc., examples of the antimony-based flame retardant include antimony trioxide, etc., and examples of the metal hydroxide flame retardant include magnesium hydroxide, etc.

[0028] From the viewpoint of obtaining good flame retardancy, it is preferable to use a mixture of two or more selected from (B-1) bromine-based flame retardant, (B-2) antimony trioxide, and (B-3) magnesium hydroxide, and it is more preferable to use a mixture of all three.

[0029] (B-1) Examples of bromine-based flame retardants include organic bromine-containing flame retardants such as brominated ethylene bisphthalimide derivatives, bis-brominated phenyl terephthalamide derivatives, brominated bisphenol derivatives, and decabromodiphenylethane. From the perspective of preventing blooming during the formation of the insulating layer, decabromodiphenylethane is particularly preferred as the bromine-based flame retardant.

[0030] (B-2) As antimony trioxide, for example, it preferably has an average particle size of around 1 μm and a purity (99.5 mass% or more) with a lead content of 1000 ppm or less, an arsenic content of 600 ppm or less, an iron oxide content of 300 ppm or less, a copper oxide content of 200 ppm or less, a selenium content of 100 ppm or less, and a cadmium content of 5 ppm or less.

[0031] (B-3) Examples of magnesium hydroxide include those with an untreated surface and those surface-treated with a silane coupling agent, a phosphate ester, or a fatty acid such as stearic acid or oleic acid.

[0032] In this embodiment, it is particularly preferable to use magnesium hydroxide surface-treated with a silane coupling agent. Magnesium hydroxide surface-treated with a silane coupling agent has a high affinity with the polymer, so that the tensile properties of the flame-retardant resin composition containing this are good.

[0033] When two or more of the above are mixed and used as the (B) flame retardant, when the (B) flame retardant is 100 mass%, it is preferably blended in the range of 10 - 80 mass% of the (B-1) bromine-based flame retardant, 10 - 80 mass% of the (B-2) antimony trioxide, and 10 - 80 mass% of the (B-3) magnesium hydroxide.

[0034] (C) Additives other than the flame retardant can be used without particular limitation as long as they are additives blended in this type of resin composition and do not inhibit the effects of this embodiment. For example, (C-1) antioxidants, (C-2) stabilizers, (C-3) copper poisoning inhibitors, (C-4) fillers, (C-5) lubricants, (C-6) crosslinking aids, etc. can be mentioned.

[0035] The blending amount of the additives other than the (C) flame retardant in this embodiment is preferably 7 to 40 parts by mass, more preferably 12 to 28 parts by mass, based on 100 parts by mass of the (A) polymer.

[0036] Here, examples of the (C-1) antioxidant include phenolic antioxidants, sulfur-based antioxidants, phenol / thioester-based antioxidants, amine-based antioxidants, phosphite-based antioxidants, etc.

[0037] Examples of the phenolic antioxidant include 1,3,5-tris[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic stearyl, 4,4'-butylidenebis-(6-tert-butyl-3-methylphenol), etc.

[0038] Examples of the sulfur-based antioxidant include ditetradecyl 3,3'-thiodipropionate, 2,2-bis[[3-(dodecylthio)-1-oxopropyl)oxy]methyl]-1,3-propanediyl bis[3-(dodecylthio)propionate], dioctadecyl 3,3'-thiodipropionate, etc.

[0039] (C-2) As the stabilizer, for example, as an anion trap agent, hydrotalcite that captures impurities in each additive and also functions as a hydrogen chloride scavenger when CPE is used in the (A) polymer can be mentioned.

[0040] As copper corrosion inhibitors, for example, hydrazides such as N’1,N’12-bis(2-hydroxybenzoyl)dodecanedihydrazide, N,N’-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, and bis(2-phenoxypropionylhydrazide) isophthalate, and 2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide, alcohol carboxylic acid esters, etc. can be mentioned.

[0041] As lubricants, for example, zinc stearate, silicone, fatty acid amide-based, hydrocarbon-based, ester-based, alcohol-based, metal soap-based, etc. can be mentioned.

[0042] As crosslinking aids, for example, trimethylolpropane trimethacrylate (TMPT), triallyl isocyanurate, triallyl cyanurate, N,N’-metaphenylene bismaleimide, ethylene glycol dimethacrylate, zinc acrylate, zinc methacrylate, etc. can be mentioned.

[0043] In addition to the materials described above, the resin composition of this embodiment may also contain fillers, pigments, etc. added within a range that does not affect the properties obtained in this embodiment.

[0044] <Method for manufacturing an insulated wire> The insulated wire 10 of this embodiment shown in FIG. 1 can be manufactured by a known method, for example, it can be manufactured as follows.

[0045] For example, a resin composition in which (A) a polymer constituting the above resin composition, (B) a flame retardant, and (C) additives other than the flame retardant optionally blended are blended is prepared. This resin composition is compounded, and further, the conductor 1 is coated by extrusion molding, and then the resin is cured by irradiating an electron beam or the like to form the insulating layer 2, whereby the insulated wire 10 is obtained.

[0046] More specifically, for example, (A) a polymer, (B) a flame retardant, and (C) an additive other than the flame retardant are melt-kneaded in a 55 L Banbury mixer at a set temperature of 100°C and a dropping temperature of 135°C. Then, the melt-kneaded resin composition is pelletized by strand cutting to obtain a compound form.

[0047] Next, the compound is extruded at an extrusion outlet temperature of 150°C using a 60 mm extruder and used to coat a separately prepared conductor 1 to produce an insulated wire. In this coating process, for example, the extruded resin composition is irradiated with an electron beam of 6 Mrad and crosslinked to form an insulating layer 2, thereby obtaining an insulated wire 10.

[0048] When crosslinking is carried out by a chemical crosslinking method, a crosslinking agent may be added to the resin composition in advance. Examples of the crosslinking agent include organic peroxides such as hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxyester, ketone peroxide ester, and ketone peroxide.

[0049] When crosslinking is carried out by silane crosslinking, in addition to the above-mentioned organic peroxide, a silane coupling agent is added in advance. Examples of the silane coupling agent include vinyl silanes such as vinyltrimethoxysilane, methacryl silanes such as 3-methacryloxypropylmethyldimethoxysilane, amino silanes such as N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and mercapto silanes such as 3-mercaptopropylmethyldimethoxysilane.

[0050] In addition, although the above-described insulated wire has been described by exemplifying one conductor 1 composed of a stranded wire, a plurality of conductors 1 may also be used. For example, as shown in FIG. 2, two conductors 1 may be arranged in parallel and a two-core parallel wire 20 in which the conductors 1 are coated with an insulating layer 2 may be obtained.

Example

[0051] (A) Polymer, (B) Flame retardant, and (C) Additives other than flame retardant, were prepared using the materials shown in Table 1 (listing the product names and manufacturers of each component). Table 2 shows the SP value and melt flow rate (MFR) for each component of (A) the polymer among those shown in Table 1. Tables 2 to 6 show the EA amount as the proportion (mass %) of units derived from ethyl acrylate in the copolymer, the VA amount as the proportion (mass %) of units derived from vinyl acetate in the copolymer, and the Cl amount as the proportion (mass %) of chlorine in the polymer, respectively.

[0052] These materials were melt-kneaded in a 55L wonder kneader at a set temperature of 100 °C and a dropping temperature of 135 °C with the formulations shown in Tables 3 to 6. Thereafter, the melt-kneaded resin composition was pelletized by strand cutting to obtain a compound form.

[0053] Next, the compound was extruded at an extrusion die temperature of 150 °C using a 60 mm extruder and used to coat separately prepared Conductor 1. The resin composition coating Conductor 1 was irradiated with an electron beam of 6 Mrad to be cured to form an insulating layer, thereby producing an insulated wire.

[0054] <Evaluation method> (1) Flame retardancy For the produced insulated wire, the vertical flame retardancy test VW-1 specified in the flame retardancy standard UL1581 was conducted 10 times. Those that passed 8 times or more were rated as "◎", those that passed 6 to 7 times were rated as "〇", and those with 5 or fewer passes were rated as "×".

[0055] (2) Printability A Teflon sheet was laid on an aluminum plate, and a 1 mm square gold frame was placed. The compound prepared was spread in the gold frame, and then a Teflon sheet and an aluminum plate were placed on it. It was preheated at 180 °C for 3 minutes under a pressure of 10 MPa for 2 minutes and then cooled to produce a 1 mm sheet. Subsequently, the sheet was irradiated with an electron beam of 6 Mrad for irradiation crosslinking. An ink solution was applied to the crosslinked sheet, and the printability was evaluated by the cross-cut test of JIS K 5600-5-6. The ink solution was prepared by mixing VS-09 black (manufactured by Teikoku Ink Co., Ltd.) as the main ink and E-003 (manufactured by Teikoku Ink Co., Ltd.) as the diluent at a general dilution rate of 20%. For the judgment of the coating film after the test, those without peeling were marked as "〇", and those with peeling were marked as "×".

[0056] (3) Surface appearance The surface roughness of the prepared insulated wire was measured with a laser microscope. The arithmetic mean roughness Ra value and the maximum height Ry value were randomly measured at three locations (n = 3), and the average value was obtained. Regarding the obtained average value, those with an Ra value less than 50 μm and an Ry value less than 100 μm were marked as "〇", and those with an Ra value of 50 μm or more or an Ry value of 100 μm or more were marked as "×".

[0057]

Table 1

[0058]

Table 2

[0059]

Table 3

[0060]

Table 4

[0061]

Table 5

[0062]

Table 6

[0063] Compared with Comparative Example 1, conventionally, when using only EEA, if the amount of the flame retardant is as much as 100 parts by mass, there is a problem with the surface appearance, but the printability and flame retardancy are good. In contrast, in Comparative Example 3, the content of the flame retardant was reduced to 50 parts by mass, and the surface appearance is good, but there are problems with printability and flame retardancy. In Comparative Example 2, the content of the flame retardant is 60 parts by mass, and although the surface appearance and flame retardancy are compatible, there is a problem with printability. This is considered to be due to a problem with the compatibility with the printing ink.

[0064] In Comparative Example 4, the polymer was changed to EVA to improve compatibility. Although the printability was improved, problems with the surface appearance occurred and they could not be made compatible. Therefore, as shown in Examples 1 to 12, in order to maintain the flame retardancy, the addition amount of the flame retardant was set between 60 and 100 parts by mass, and by containing 5 to 20% by mass of a high-MFR ethylene copolymer having an MFR of 9 to 100 [g / 10 min] in the polymer component, the extrusion fluidity was improved and it was found that the surface appearance of the wire could be exhibited. Further, by setting the SP value of the mixed polymer to 8.73 or more, the compatibility with the printing ink was enhanced, the printability was improved, and all the properties of flame retardancy, surface appearance, and printability were successfully made good.

[0065] From Comparative Examples 5 to 8, it was found that when the addition amount of the high-MFR ethylene copolymer was less than 5% by mass, a satisfactory effect could not be obtained, and when it exceeded 20% by mass, the flow became unstable and the appearance could not be maintained.

[0066] Also, from Comparative Examples 9 and 10, it was found that even when containing 5 to 20% by mass of a high-MFR ethylene copolymer, if the SP value of the mixed polymer is not 8.73 or more, the compatibility with the printing ink is inferior and it is difficult to achieve compatibility with printability.

[0067] Regarding flame retardancy, it was also found that the resin compositions containing CPE in the polymer component and having a chlorine content of 1 to 5% by mass in the polymer component according to Examples 1 to 5 and 8 to 12 can exhibit higher flame retardancy than conventional ones.

[0068] From the above, according to this embodiment, an excellent insulated wire having well-balanced flame retardancy, surface appearance, and printability can be obtained.

[0069] As described above, the invention made by the present inventors has been specifically described based on the embodiments. However, it goes without saying that the present invention is not limited to the above embodiments and can be variously modified without departing from the gist thereof.

Explanation of Reference Numerals

[0070] 1 Conductor 2 Insulation layer 10 Insulated wire

Claims

1. An insulated electric wire having a conductor and an insulating layer covering the conductor, wherein the insulating layer is composed of a resin composition having: (A) a polymer containing (A-1) an ethylene copolymer having a melt flow rate (MFR) of 2 [g / 10 min] or less and (A-2) an ethylene copolymer having a melt flow rate (MFR) of 9 to 100 [g / 10 min]; and (B) a flame retardant. The polymer (A) contains 5 to 20% by mass of the component (A-2) and has an SP value of 8.73 or more. The flame retardant (B) contains three types of flame retardants: (B-1) a brominated flame retardant, (B-2) antimony trioxide, and (B-3) magnesium hydroxide, and is contained in the range of 60 to 100 parts by mass with respect to 100 parts by mass of the polymer (A). An insulated electric wire characterized by the above.

2. The insulated electric wire according to Claim 1, wherein the ethylene copolymer is an ethylene-ethyl acrylate copolymer (EEA) or an ethylene-vinyl acetate copolymer (EVA). An insulated electric wire characterized by the above.

3. The insulated electric wire according to Claim 1 or 2, wherein the polymer (A) contains chlorinated polyethylene (CPE), and the chlorine content in the polymer (A) is 1 to 5% by mass. An insulated electric wire characterized by the above.

4. The insulated electric wire according to any one of Claims 1 to 3, further containing (C) an additive other than the flame retardant. An insulated electric wire characterized by the above.

5. The insulated electric wire according to any one of Claims 1 to 4, wherein the insulated electric wire is a two-core parallel electric wire. An insulated electric wire characterized by the above.

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