Non-halogen flame-retardant resin composition and insulated wire

Abstract

To provide a non-halogen flame-retardant resin composition with excellent wear resistance and smoke characteristics, and an insulated wire including the resin composition.SOLUTION: An insulated wire has a conductor 11a and an insulating layer that is provided around the conductor 11a and consists of an inner insulating layer 11b and an outer insulating layer 11c, where the outer insulating layer 11c is composed of a non-halogen flame-retardant resin composition that contains a crystalline polymer containing polybutylene terephthalate resin as a base polymer, a phosphorous compound, an ethylene glycidyl methacrylate copolymer, a porous inorganic filler, and a hydrolysis resistance improver. Based on the base polymer 100 pts.mass, the phosphorous compound is 1-30 pts.mass, the ethylene glycidyl methacrylate copolymer is 1-50 pts.mass, the porous inorganic filler is 0.1-50 pts.mass, and the hydrolysis resistance improver is 0.05-10 pts.mass.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a halogen-free flame-retardant resin composition and an insulated wire. [Background technology]

[0002] Polyvinyl chloride resin (PVC) is generally used as a wire covering material for railroad cars, automobiles, equipment, etc. PVC has high practical properties and is inexpensive, but it generates halogen gas containing chlorine when incinerated after disposal, which causes environmental pollution problems associated with waste disposal. In recent years, non-halogen materials other than PVC have been increasingly used. In addition, in the transportation field, such as railroad cars and automobiles, there is a demand for lighter and thinner electric wires in line with the need to reduce the weight and space of car bodies to save energy. When conventional PVC materials are used to reduce the weight and thickness of such electric wires, there are problems such as the inability to achieve the required properties of flame retardancy and abrasion resistance.

[0003] On the other hand, polyester resins, which are general-purpose engineering plastic polymers, and polybutylene terephthalate (PBT) in particular, are crystalline polymers that have excellent heat resistance, mechanical strength, electrical properties, chemical resistance, and moldability. They also have low water absorption and excellent dimensional stability, and are relatively easy to make flame retardant. Taking advantage of these characteristics, they are used in a wide range of fields, including automobiles, electrical appliances, electronics, insulation materials, and office automation.

[0004] However, since PBT is crystalline, the degree of crystallinity may change during the manufacturing process or in certain environments, which may result in a decrease in tensile elongation properties, for example. To solve these problems, a technique for adding polyorganosiloxane is known (for example, see Patent Document 1).

[0005] However, this technology is still insufficient to meet the high level of specifications that require even greater wear properties, and there is also the problem that it has only a small effect in suppressing smoke generated during combustion. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5233609 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a halogen-free, flame-retardant resin composition having excellent abrasion resistance and smoke generation properties, and an insulated wire using the resin composition. [Means for solving the problem]

[0008] A halogen-free flame-retardant resin composition according to one embodiment contains a crystalline polymer including a polybutylene terephthalate resin as a base polymer, a phosphorus-based compound, an ethylene glycidyl methacrylate copolymer, an inorganic porous filler, and a hydrolysis resistance improver, and contains 1 to 30 parts by mass of the phosphorus-based compound, 1 to 50 parts by mass of the ethylene glycidyl methacrylate copolymer, 0.1 to 50 parts by mass of the inorganic porous filler, and 0.05 to 10 parts by mass of the hydrolysis resistance improver relative to 100 parts by mass of the base polymer.

[0009] An insulated wire according to one embodiment has a conductor and an insulating layer provided around the conductor, and the insulating layer is made of a halogen-free flame-retardant resin composition containing a crystalline polymer including a polybutylene terephthalate resin as a base polymer, a phosphorus-based compound, an ethylene glycidyl methacrylate copolymer, an inorganic porous filler, and a hydrolysis resistance improver, the composition containing 1 to 30 parts by mass of the phosphorus-based compound, 1 to 50 parts by mass of the ethylene glycidyl methacrylate copolymer, 0.1 to 50 parts by mass of the inorganic porous filler, and 0.05 to 10 parts by mass of the hydrolysis resistance improver relative to 100 parts by mass of the base polymer. Effect of the Invention

[0010] According to the present embodiment, it is possible to provide a halogen-free, flame-retardant resin composition having excellent abrasion resistance and smoke generation properties, and an insulated wire using the resin composition. [Brief description of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view showing a configuration example of an insulated wire according to an embodiment. [Diagram 2] 1 is a cross-sectional view showing an example of the configuration of a cable according to an embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] <Halogen-free flame-retardant resin composition> [Polymer component] The polymer component of the resin composition used in this embodiment uses a crystalline polymer as the base polymer. The inclusion of a crystalline polymer improves the abrasion resistance of the insulating layer. Therefore, it is preferable that the base polymer does not contain a non-crystalline polymer.

[0014] As the crystalline polymer, polybutylene terephthalate (PBT) resin is used. PBT resin is a polyester mainly composed of butylene terephthalate repeating units, and is a polyester mainly composed of butylene terephthalate repeating units obtained by using 1,4-butanediol as a polyhydric alcohol component and terephthalic acid or its ester derivative as a polyvalent carboxylic acid component.

[0015] The main repeating unit means that the butylene terephthalate unit accounts for 70 mol % or more of the total polyvalent carboxylic acid-polyhydric alcohol units. Furthermore, the butylene terephthalate unit accounts for preferably 80 mol % or more, more preferably 90 mol % or more, and even more preferably 95 mol % or more.

[0016] Examples of polycarboxylic acid components other than terephthalic acid used in PBT resins include aromatic polycarboxylic acids such as 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, isophthalic acid, phthalic acid, trimesic acid, and trimellitic acid, aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and decanedicarboxylic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, and ester-forming derivatives of the above polycarboxylic acids (for example, lower alkyl esters of polycarboxylic acids such as dimethyl terephthalate), etc. These polycarboxylic acid components may be used alone or in combination.

[0017] On the other hand, examples of polyhydric alcohol components other than 1,4-butanediol include aliphatic polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, neopentyl glycol, pentanediol, hexanediol, glycerin, trimethylolpropane, and pentaerythritol, alicyclic polyhydric alcohols such as 1,4-cyclohexanedimethanol, aromatic polyhydric alcohols such as bisphenol A and bisphenol Z, and polyalkylene glycols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and polytetramethylene oxide glycol. These polyhydric alcohol components may be used alone or in combination. Furthermore, the PBT resin used in this embodiment has a terminal carboxyl group equivalent of 50 (eq / T) or less, preferably 40 (eq / T) or less, and more preferably 30 (eq / T) or less, from the viewpoint of hydrolysis resistance. If the terminal carboxyl group equivalent exceeds 50 (eq / T), the hydrolysis resistance is deteriorated.

[0018] The PBT resin in the present embodiment may be a single resin or a mixture of a plurality of resins differing in terminal carboxyl group concentration, melting point, catalyst amount, etc., so long as it satisfies the above-mentioned requirements.

[0019] Also, a crystalline polymer other than PBT resin can be mixed and used. The crystalline polymer that can be used in this case is not particularly limited as long as it is a known crystalline polymer, and examples thereof include non-halogen crystalline engineering plastics such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), polyamide (PA), polyacetal (POM), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), and liquid crystal polymer (LCP).

[0020] When a plurality of crystalline polymers are mixed, the crystalline polymers preferably contain 80% by mass or more of PBT resin, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0021] [Phosphorus compounds] The phosphorus-based compound used in this embodiment can be any phosphorus-based compound known as a flame retardant, such as phosphate esters, phosphonitrile compounds, and polyphosphates, with phosphate esters being preferred.

[0022] Specific examples of the phosphoric acid ester include trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, etc. Among them, the phosphoric acid ester compound represented by the following chemical formula (1) is preferable.

[0023] In chemical formula (1), R 1 ~R 8 represents a hydrogen atom or an alkyl group having 6 or less carbon atoms. In order to improve hydrolysis resistance, an alkyl group having 6 or less carbon atoms is preferred, and a methyl group is particularly preferred. n represents an integer of 0 to 10. Here, n is preferably 1 to 3, and particularly preferably 1.

[0024] Also, R 9represents a divalent or higher organic group. In this case, the divalent or higher organic group means a divalent or higher group obtained by removing one or more hydrogen atoms bonded to carbon of an alkyl group, a cycloalkyl group, an aryl group, etc. from an organic group. Specifically, the structure shown in the following chemical formula (2) is preferably exemplified.

[0025] [ka]

[0026] [ka]

[0027] As the phosphorus-based compound, a phosphonitrile compound having a group represented by the following chemical formula (3) is also preferably used.

[0028] In chemical formula (3), R 10 , R 11 represents an aryl group, an alkyl group, or a cycloalkyl group having 1 to 20 carbon atoms, specific examples of which include methyl, ethyl, butyl, hexyl, cyclohexyl, phenyl, benzyl, naphthyl, etc. n and m each represent an integer, generally 1 to 4, and particularly preferably 3 or 4.

[0029] The phosphonitrile compound may be a linear polymer or a cyclic polymer, of which cyclic polymers are preferably used. X represents an atom or group of -O-, -S-, or -N(-H)-, of which -O- and -N(-H)- are more preferred, and -O- is particularly preferred.

[0030] [ka]

[0031] The polyphosphate salt may be melem polyphosphate. Ammonium polyphosphate may also be preferably used. The average particle size of the phosphorus compound is preferably 0.05 to 100 μm, more preferably 0.1 to 80 μm.

[0032] The amount of the phosphorus-based compound is 1 to 30 parts by mass, preferably 2 to 25 parts by mass, more preferably 3 to 20 parts by mass, and particularly preferably 5 to 15 parts by mass, relative to 100 parts by mass of the base polymer. If the amount of the phosphorus-based compound exceeds 30 parts by mass, blooming may occur, and if it is less than 1 part by mass, the flame retardancy may be insufficient. [Ethylene glycidyl methacrylate copolymer]

[0033] The ethylene glycidyl methacrylate copolymer used in this embodiment is a copolymer of glycidyl methacrylate (GMA) and ethylene, and is a component that imparts impact resistance and absorption properties to the resin composition containing PBT resin. It is also a component that thickens the resin composition containing PBT resin and imparts the effect of suppressing the propagation of flames during combustion. Therefore, the impact resistance and absorption properties improve the abrasion resistance, suppress the propagation of flames, and reduce the burning area of ​​the resin composition, thereby reducing the smoke density of the smoke generated during combustion.

[0034] The amount of the ethylene glycidyl methacrylate copolymer is 1 to 50 parts by mass, preferably 2 to 40 parts by mass, more preferably 3 to 30 parts by mass, and particularly preferably 5 to 20 parts by mass, relative to 100 parts by mass of the base polymer. If the amount of the ethylene glycidyl methacrylate copolymer exceeds 50 parts by mass, the abrasion properties may be reduced, and if it is less than 1 part by mass, the heat resistance may be reduced.

[0035] The amount of GMA modification of the ethylene glycidyl methacrylate copolymer is not particularly limited, but is preferably 6% by mass or less for ease of handling during extrusion molding. [Inorganic porous filler]

[0036] The inorganic porous filler used in this embodiment is an inorganic porous filler that has the effect of trapping ions contained in the resin composition, and is a component that suppresses deterioration of the insulating layer of the insulated electric wire and stabilizes it. In order to fully exert the above effect, this inorganic porous filler has a specific surface area of ​​5 m 2 It is preferable that the molecular weight is 1 / g or more.

[0037] Examples of the inorganic porous filler include calcined clay, zeolite, mesalite, anthracite, perlite foam, activated carbon, etc., and these may be used alone or in combination of two or more. The inorganic porous filler preferably contains calcined clay.

[0038] The amount of the inorganic porous filler is preferably 0.1 to 50 parts by mass, and more preferably 0.5 to 10 parts by mass, relative to 100 parts by mass of the base polymer. If the content of the inorganic porous filler is less than 0.1 part by weight, ions may not be trapped sufficiently, making it difficult to achieve the effects of the present invention, whereas if it is more than 50 parts by mass, the dispersibility of the inorganic porous filler may decrease, and the tensile properties of the insulated wire may decrease.

[0039] [Hydrolysis resistance improver] The hydrolysis resistance improver used in this embodiment contains a compound that suppresses hydrolysis of the PBT resin. That is, the hydrolysis resistance improver is an additive that improves (improves) the hydrolysis resistance in the resin composition, and a known compound can be used. Here, the PBT resin is hydrolyzed by water vapor contained in the external atmosphere, which can cause a decrease in molecular weight and a decrease in mechanical strength, etc., so this hydrolysis resistance improver can suppress this and stably maintain the characteristics of the insulating layer of the insulated wire.

[0040] Examples of the hydrolysis resistance improver include carbodiimide compounds, epoxy compounds, oxazoline compounds, and oxazine compounds. Among these, carbodiimide compounds are preferred because they can be used without impairing the coating processability of the resin composition.

[0041] A carbodiimide compound is a compound having at least two carbodiimide groups (-N=C=N-) in one molecule, and can be produced, for example, by subjecting a polyfunctional isocyanate compound having at least two isocyanate groups in the molecule to a carbon dioxide removal condensation polymerization reaction (carbodiimide reaction) in the presence of a carbodiimide catalyst.

[0042] The carbodiimidization reaction can be carried out by a known method. Specifically, a condensation reaction accompanied by decarbonation (carbodiimidization reaction) can be carried out by dissolving an isocyanate in an inert solvent, or adding a carbodiimidization catalyst such as an organic phosphorus compound represented by phosphorene oxides in the absence of a solvent under a stream or bubbling of an inert gas such as nitrogen, and heating and stirring in the temperature range of 150 to 200°C.

[0043] As the polyisocyanate compound used in this reaction, a bifunctional isocyanate having two isocyanate groups in the molecule is particularly suitable, but an isocyanate compound having three or more isocyanate groups can also be used in combination with a diisocyanate. The polyisocyanate compound may be either an aliphatic isocyanate or an alicyclic isocyanate.

[0044] Specific examples of polyisocyanate compounds include hexamethylene diisocyanate (HDI), hydrogenated xylylene diisocyanate (H6XDI), xylylene diisocyanate (XDI), 2,2,4-trimethylhexamethylene diisocyanate (TMHDI), 1,12-diisocyanate dodecane (DDI), norbornane diisocyanate (NBDI), 2,4-bis-(8-isocyanate octyl)-1,3-dioctylsilane, and the like. Examples include cyclobutane diisocyanate (ODI), 4.4'-dicyclohexylmethane diisocyanate (HMDI), tetramethylxylylene diisocyanate (TMXDI), isophorone diisocyanate (IPDI), 2,4,6-triisopropylphenyl diisocyanate (TIDI), 4,4'-diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), and hydrogenated tolylene diisocyanate (HTDI).

[0045] More specifically, the carbodiimide compound used in this embodiment is preferably a carbodiimide compound obtained from HDMI or MDI, and commercially available products such as "Carbodilite" (product name: manufactured by Nisshinbo Co., Ltd.) and "Stavaxol P" (product name: manufactured by Rhein Chemie AG) may also be used.

[0046] The amount of the hydrolysis resistance improver is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, relative to 100 parts by mass of the base polymer. If the amount of the hydrolysis resistance improver is less than 0.05 parts by mass, the effect of improving hydrolysis resistance may not be expected, whereas if it is more than 10 parts by weight, the fluidity may decrease, and the moldability of the resin composition may decrease.

[0047] <Insulated wire> The insulated wire of the present embodiment has a conductor and an insulating layer provided on the conductor, and the insulating layer is configured to contain the above-described halogen-free flame-retardant resin composition.

[0048] FIG. 1 is a cross-sectional view showing an example of the configuration of an insulated wire according to an embodiment. The insulated wire 11 shown in FIG. 1 has a conductor 11a, an inner insulating layer 11b formed on the outer periphery of the conductor 11a, and an outer insulating layer 11c formed on the outer periphery of the inner insulating layer 11b. In this manner, the insulating layer covering the conductor 11a may have a two-layer structure of the inner insulating layer 11b and the outer insulating layer 11c. Although FIG. 1 shows an example of a two-layer insulating layer, this insulating layer may be an insulating layer having a single flame-retardant insulating layer, or may be an insulating layer having a multiple flame-retardant insulating layer of three or more layers. Features of the insulated wire 11 will be described below.

[0049] [conductor] The conductor 11a may be, for example, a stranded wire in which a plurality of strands (metal wires) are stranded together. The strands may be, for example, copper wires, copper alloy wires, aluminum wires, gold wires, silver wires, or the like, and may be metal-plated, such as tin or nickel, on the outer periphery.

[0050] [Insulation layer] The insulating layer includes a resin layer (flame-retardant insulating layer) made of a material containing a specific polymer material, and is composed of an insulating inner layer 11b and an insulating outer layer 11c.

[0051] (insulating outer layer) The insulating outer layer 11c is formed using a resin composition containing the specific polymer component and other components described above. By using the resin composition as the outermost layer of the insulated wire in this manner, an insulated wire having excellent abrasion resistance and low smoke generation properties can be obtained.

[0052] (insulating inner layer) The insulating inner layer 11b can be formed from a known resin composition used for flame-retardant insulated wires.

[0053] The flame retardant contained in the resin composition constituting the insulating inner layer 11b may be a known halogen-free flame retardant that is blended into this type of resin composition, and is preferably a metal hydroxide. Any known metal hydroxide may be used as the metal hydroxide, but magnesium hydroxide and aluminum hydroxide are particularly preferred. These may be used alone or in combination.

[0054] Magnesium hydroxide is more preferable because its main dehydration reaction is as high as 350℃, making it easier to handle the high molding temperature of the outer layer, and it also has good flame retardancy. These metal hydroxides contribute to suppressing smoke generation during combustion through the dilution effect caused by the endothermic reaction and the diffusion of water due to dehydration. Among non-halogen flame retardants, red phosphorus is not suitable because there is a risk of contact damage with phosphine gas, etc.

[0055] Other applicable specific non-halogen flame retardants include melamine cyanurate, clay, silica, zinc stannate, zinc borate, calcium borate, dolomide hydroxide, and silicone.

[0056] In consideration of dispersibility, the flame retardant may be surface-treated with a silane coupling agent, a titanate coupling agent, a fatty acid such as stearic acid, etc. The amount of flame retardant added is not particularly limited, but when magnesium hydroxide or aluminum hydroxide is highly loaded, it is preferably 100 to 300 parts by mass per 100 parts by mass of the base polymer. If it is less than 100 parts by mass, it may be difficult to fully satisfy the flame retardancy, and if it is more than 300 parts by mass, the low temperature property may be insufficient. More preferably, it is 100 to 250 parts by mass, and even more preferably 100 to 200 parts by mass.

[0057] The base polymer constituting the insulating inner layer 11b may be a halogen-free polyolefin and is not particularly limited, but it is preferable that the base polymer contains a polyolefin having a melting point peak of 120° C. or higher as measured by DSC, since this tends to provide high mechanical properties.

[0058] Examples of polyolefins having a melting point of 120°C or higher include linear low-density polyethylene, high-density polyethylene, and polypropylene. These materials may be modified with an acid such as maleic acid. Examples of polymers having a melting point of 120°C or higher include engineering plastics such as polybutylene terephthalate, but these are not applicable because it is difficult to highly fill the non-halogen flame retardant. In this resin composition, the use of a polyolefin having a melting point of less than 120°C is useful for increasing the acceptance of the flame retardant. Examples of polymers having a melting point of less than 120°C include low-density polyethylene, very low-density polyethylene, ethylene-acrylic acid ester copolymer, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, ethylene-octene copolymer, ethylene-butene copolymer, and butadiene-styrene copolymer.

[0059] The crosslinking treatment can be carried out as necessary. Examples of the crosslinking include chemical crosslinking using an organic peroxide, a sulfur compound, or silane, irradiation crosslinking using an electron beam or radiation, and crosslinking using other chemical reactions. Any crosslinking method can be used.

[0060] To the resin composition composed of these materials, crosslinking agents, crosslinking assistants, ultraviolet absorbers, light stabilizers, softeners, lubricants, colorants, reinforcing materials, surfactants, inorganic fillers, antioxidants, plasticizers, metal chelating agents, foaming agents, compatibilizers, processing assistants, stabilizers, etc. may be added as necessary.

[0061] The insulated wire 11 of the present embodiment can be configured as described above. In this case, the thickness of the insulating layer (the total thickness of the insulating inner layer 11b and the insulating outer layer 11c) can be any thickness, but even if the thickness is about 0.1 to 0.5 mm, sufficient flame retardancy and insulation can be ensured.

[0062] Furthermore, in the insulating layer, the ratio of the thickness Tb of the insulating inner layer 11b to the thickness Tc of the insulating outer layer 11c can be set to Tb:Tc=1:4 to 4:1.

[0063] 1, the insulating layer covering the conductor 11a has a two-layer structure consisting of an inner insulating layer 11b and an outer insulating layer 11c, but it may have a three or more layer structure or may be a single layer. In either case, by using the above-mentioned non-halogen flame-retardant resin composition as the outermost layer, the characteristics of the non-halogen insulated wire can be improved.

[0064] The insulated wire 11 of the present embodiment is manufactured, for example, as follows. First, a resin composition for forming the insulating inner layer 11b and the insulating outer layer 11c is prepared. In the present embodiment, the resin composition is obtained by melt-kneading materials including, for example, a crystalline polymer including a PBT resin as a base polymer, a phosphorus-based compound, an ethylene glycidyl methacrylate copolymer, an inorganic porous filler, and a hydrolysis resistance improver.

[0065] Thereafter, the conductor 11a is prepared. Then, the resin composition is extruded by an extrusion molding machine so as to cover the periphery of the conductor 11a, thereby forming the insulating inner layer 11b, and then the resin composition of the present embodiment is extruded so as to cover the periphery of the insulating inner layer 11b, thereby forming the insulating outer layer 11c. Furthermore, the resin composition is crosslinked as necessary, thereby manufacturing the insulated electric wire 11.

[0066] <Cable> Next, a cable according to an embodiment will be described with reference to Fig. 2. Fig. 2 is a cross-sectional view showing an example of the configuration of a cable according to the present embodiment.

[0067] As shown in Fig. 2, the cable 12 according to the present embodiment includes two twisted insulated electric wires 11 (twisted core, see Fig. 1), a separator 12b provided on the outside of the twisted core, a shield braid 12c provided so as to cover the separator, and a sheath (outer jacket layer, covering layer) 12d that covers the shield braid 12c. By using the above-mentioned non-halogen flame-retardant resin composition for the sheath 12d, the characteristics of the non-halogen cable can be improved.

[0068] The number of insulated wires 11 may be one or more. The material of separator 12b is not particularly limited, and it may be provided on the outside of shield braid 12c. Shield braid 12c is made of a conductive material, typically a metal material, to provide a shielding effect.

[0069] There is no limitation on the applications of such insulated wires and cables, but they can be used, for example, as insulated wires or cables for railroad cars.

[0070] The cable 12 of the present embodiment is manufactured, for example, as follows. First, two insulated electric wires 11 are manufactured by the above-mentioned method. Then, the two insulated electric wires 11 are twisted together with staple yarn, paper tape, jute, or the like, and then, a separator 12b and a shield braid 12c are formed in this order by a known method so as to cover the twisted electric wires. Furthermore, the resin composition of the present embodiment is extruded around the outer periphery of the shield braid 12c thus obtained, in the same manner as in the above-mentioned method for manufacturing an electric wire, to form a sheath 12d of a predetermined thickness. In this manner, the cable 12 of the present embodiment can be manufactured.

[0071] In the above, the cable 12 of this embodiment has been described using the above-mentioned insulated wire 11 as an example, but this is not limited to this, and it is also possible to use an insulated wire that uses a general-purpose material for the insulating layer. EXAMPLES

[0072] The halogen-free flame-retardant resin composition and the insulated wire according to the present embodiment will be described in more detail below with reference to examples and comparative examples; however, the present invention is not limited to these examples.

[0073] [Examples 1 to 4, Comparative Examples 1 to 2] (Production of resin composition) To prepare the resin composition for forming the insulating outer layer, the components were blended in the ratios shown in Tables 1 and 2, and the blend was melt-kneaded and extruded into strands using a 30 mm twin-screw extruder at a cylinder temperature setting of 260°C, a screw rotation speed of 250 rpm, and a discharge rate of 40 kg / hr. The resulting mixture was then pelletized using a strand cutter to obtain resin composition pellets having the polybutylene terephthalate resin as the base polymer in Examples 1 to 4 and Comparative Examples 1 and 2.

[0074] In addition, as a resin composition for forming the insulating inner layer, the components shown in Table 1 were kneaded in a 14-inch oven roll and molded into square pellets to obtain a resin composition.

[0075] (Wire manufacturing) Using the above resin composition, an insulated wire was produced as follows so as to have the configuration of insulated wire 11 shown in FIG.

[0076] First, a tin-plated conductor with a composition of 50 wires / 0.18 mm was used as the conductor. The pellets of each resin composition obtained above were kneaded using a twin-screw extruder (screw diameter 30 mm, L / D: 30). The kneaded resin obtained was extruded into two layers using a 40 mm extruder, and coated to an insulated electric wire with an outer diameter of 2.2 mm. The insulated electric wire obtained was irradiated with an electron beam for crosslinking. Tables 1 and 2 show the composition of the resin composition, as well as the electric wire structure (insulation layer thickness) and the evaluation results of the characteristics.

[0077] [Characteristics test] The abrasion resistance of the obtained insulated wires was evaluated by an abrasion test method conforming to the UL standard, with the abrasion resistance being judged as ⊚ (good) for 200 or more abrasion cycles, ◯ (passable) for 100 or more abrasion cycles, and × (unacceptable) for less than 100 cycles.

[0078] The smoke generation resistance of the obtained insulated wire was evaluated by a smoke generation test using the flaming method in accordance with JIS C 0081. At this time, a smoke generation density of 130 or less was judged as ◎ (good), 210 or less was judged as ○ (passable), and 200 or more was judged as × (unacceptable).

[0079] In the above test method, the overall evaluation was rated as ☆ (good) when all evaluations were ☆ or ◯, and ☆ (poor) when some were ×.

[0080] In Examples 1 and 2, the single-layer insulating material was a resin composition based on polybutylene terephthalate PBT (Mitsubishi Chemical Engineering Plastics, Novadilan 5026), and all evaluations were rated as ◎ or ◯, so the overall evaluation was ◎.

[0081] In Examples 3 and 4, a resin composition based on polybutylene terephthalate PBT (Mitsubishi Chemical Engineering Plastics, Novadilan 5026) was used as the outer insulating layer, and a resin composition based on high-density polyethylene was used as the inner insulating layer. All evaluations were rated as ◎ or ◯, so the overall evaluation was ◎.

[0082] Comparative Example 1 used a resin composition based on polybutylene terephthalate PBT (Mitsubishi Chemical Engineering Plastics, Novadilan 5026) as a single-layer insulating material, and since the abrasion test and smoke generation test were both poor, the overall evaluation was poor.

[0083] Comparative Example 2 used a resin composition based on polybutylene terephthalate PBT (Mitsubishi Chemical Engineering Plastics, Novadilan 5026) for the outer insulating layer, and a resin composition based on high-density polyethylene for the inner insulating layer. Since the abrasion test was poor, the overall evaluation was poor.

[0084] [Table 1]

[0085] [Table 2]

[0086] (Basis for optimal conditions) It was found that insulated wires with an insulation layer containing a non-halogen flame retardant, abrasion resistance and low smoke generation can be sufficiently improved by using PBT resin as the base polymer constituting the insulation layer and blending ethylene glycidyl methacrylate copolymer as an impact absorbing agent. In addition, it was found that smoke generation properties can be further improved by forming the insulation inner layer using a polyolefin material highly filled with metal hydroxides such as magnesium hydroxide. [Explanation of symbols]

[0087] 11 Insulated wire 11a Conductor 11b Insulating inner layer 11c Insulating outer layer 12 Cable 12b Separator 12c shield braid 12d Sheath

Claims

1. A halogen-free flame-retardant resin composition comprising a crystalline polymer including a polybutylene terephthalate resin as a base polymer, a phosphorus-based compound, an ethylene glycidyl methacrylate copolymer, an inorganic porous filler, and a hydrolysis resistance improver, A halogen-free flame-retardant resin composition comprising, relative to 100 parts by mass of the base polymer, 1 to 30 parts by mass of the phosphorus-based compound, 1 to 50 parts by mass of the ethylene glycidyl methacrylate copolymer, 0.1 to 50 parts by mass of the inorganic porous filler, and 0.05 to 10 parts by mass of the hydrolysis resistance improver.

2. The halogen-free flame-retardant resin composition according to claim 1, The halogen-free flame-retardant resin composition, wherein the hydrolysis resistance improver is a carbodiimide compound.

3. An insulated wire having a conductor and an insulating layer provided around the conductor, The insulating layer contains a crystalline polymer including a polybutylene terephthalate resin as a base polymer, a phosphorus-based compound, an ethylene glycidyl methacrylate copolymer, an inorganic porous filler, and a hydrolysis resistance improver, and is composed of a halogen-free flame-retardant resin composition containing, relative to 100 parts by mass of the base polymer, 1 to 30 parts by mass of the phosphorus-based compound, 1 to 50 parts by mass of the ethylene glycidyl methacrylate copolymer, 0.1 to 50 parts by mass of the inorganic porous filler, and 0.05 to 10 parts by mass of the hydrolysis resistance improver.

4. The insulated wire according to claim 3, The insulated wire according to claim 1, wherein the hydrolysis resistance improver is a carbodiimide compound.

5. The insulated wire according to claim 3, The insulating layer has a thickness of 0.1 to 0.5 mm.

6. An insulated wire having a conductor and an insulating layer having a two-layer structure including an insulating inner layer and an insulating outer layer, the insulating layer being provided around the conductor, the insulating inner layer is made of a flame-retardant resin composition containing a polyolefin resin and a metal hydroxide, the flame-retardant resin composition containing 100 to 300 parts by mass of the metal hydroxide per 100 parts by mass of the polyolefin resin; The insulating outer layer is a halogen-free flame-retardant resin composition containing a crystalline polymer including a polybutylene terephthalate resin as a base polymer, a phosphorus-based compound, an ethylene glycidyl methacrylate copolymer, an inorganic porous filler, and a hydrolysis resistance improver, the halogen-free flame-retardant resin composition containing, relative to 100 parts by mass of the base polymer, 1 to 30 parts by mass of the phosphorus-based compound, 1 to 50 parts by mass of the ethylene glycidyl methacrylate copolymer, 0.1 to 50 parts by mass of the inorganic porous filler, and 0.05 to 10 parts by mass of the hydrolysis resistance improver.

7. The insulated wire according to claim 6, The insulated wire according to claim 1, wherein the hydrolysis resistance improver is a carbodiimide compound.

8. The insulated wire according to claim 6, 1. An insulated wire, wherein the metal hydroxide contained in the inner insulating layer comprises magnesium hydroxide and / or aluminum hydroxide.

9. The insulated wire according to claim 6, The insulated wire, wherein the insulating layer has a total thickness of 0.1 to 0.5 mm.

10. The insulated wire according to claim 6, The insulated wire has a ratio of a thickness Tb of the inner insulating layer to a thickness Tc of the outer insulating layer of Tb:Tc=1:4 to 4:1.

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