JP7331705B2 - Non-halogen resin composition, wire and cable - Google Patents

Description

The present invention relates to non-halogen resin compositions, electric wires and cables.

Properties such as flame retardancy, oil resistance, and low temperature resistance are required for cables used in railway vehicles, automobiles, and the like. In order to obtain high flame retardancy, materials obtained by adding halogen-based flame retardants such as chlorine-based or bromine-based flame retardants to polyolefin are used. However, substances containing a large amount of these halogen-based flame retardants generate a large amount of toxic and harmful gases when burned and, depending on the incineration conditions, generate highly toxic dioxins. For this reason, cables using non-halogen materials (halogen-free materials) that do not contain halogen substances as coating materials are becoming popular from the viewpoint of fire safety and environmental load reduction.

For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2002-42575), insulation is achieved by adding 150 to 300 parts by mass of a metal hydrate to 100 parts by mass of a base resin containing an ethylene/vinyl acetate copolymer. Techniques for improving the flame retardancy of electric wires have been disclosed.

However, non-halogen materials tend to be inferior to conventional halogen-containing materials in flame retardancy, oil resistance, and low-temperature properties due to the difference in the chemical structure of the base polymer and the difference in flame retardant mechanism.

In particular, insulated wires and cables used in railway vehicles have the risk of causing serious accidents due to their defects. is required.

For example, Patent Document 2 (Japanese Patent Application Laid-Open No. 2014-24910) describes LLDPE at 60 to 70% by mass, EVA having a melt flow rate (MFR) of 100 or more at 10% by mass or more, and maleic acid-modified polyolefin at 10 to A halogen-free flame-retardant resin composition comprising a base polymer containing 20% by mass, a metal hydroxide added at a rate of 150 to 220 parts by mass with respect to 100 parts by mass of the base polymer, and carbon black. A cable is disclosed which has flame retardancy and improved oil resistance, low-temperature properties, and resistance to trauma by using the material.

JP-A-2002-42575 JP 2014-24910 A

The present inventor is engaged in research and development of coating materials such as the jacket layer of cables and the insulation layer of insulated wires. We are investigating a resin composition that has good heat resistance and low-temperature properties. For example, when blending polymers with greatly different viscosities, such as the resin described in Patent Document 2, the dispersibility of the polymer deteriorates. Faced with the difficulty, further improvement of the properties of the resin as a coating material has been desired.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a non-halogen resin composition having good flame retardancy, oil resistance and low temperature properties, and an insulated wire or cable using the same.

(1) A non-halogen resin composition of one aspect of the present invention is a non-halogen resin composition containing a base polymer, a metal hydroxide and carbon black, wherein the base polymer contains 60 to 70 parts by mass of polyolefin. , 10 to 35 parts by mass of maleic anhydride-modified polyolefin, 5 to 30 parts by mass of ethylene-vinyl acetate copolymer, and 150 to 250 parts by mass of the metal hydroxide per 100 parts by mass of the base polymer. parts by mass, the carbon black is contained in a proportion of 1 to 30 parts by mass with respect to 100 parts by mass of the base polymer, the melting point of the polyolefin is 110 ° C. or higher, and the gel content after cross-linking rate is 85% or more.

(2) For example, the amount of the maleic anhydride-modified polyolefin added to the base polymer is 25 to 35 parts by mass.

(3) For example, the polyolefin is polyethylene.

(4) For example, the content of acetic acid (CH ₃ COO-) in the ethylene-vinyl acetate copolymer is 2.3% by mass or more relative to the base polymer.

(5) For example, the content of acetic acid (CH ₃ COO—) in the ethylene-vinyl acetate copolymer is 6% by mass or more relative to the base polymer.

(6) The electric wire of one aspect of the present invention includes an insulating layer formed from the non-halogen resin composition.

(7) A cable according to one aspect of the present invention includes a jacket layer formed from the non-halogen resin composition.

By using the non-halogen resin composition of one embodiment of the present invention as a coating material for insulated wires and cables, flame retardancy, oil resistance, and low-temperature properties can be improved.

It is a sectional view showing an example of composition of an insulated wire. 4 is a cross-sectional view showing a configuration example of a cable; FIG.

(Embodiment)
Coating materials such as the jacket layer of cables and the insulating layers of insulated wires are made of non-halogen resin compositions. Therefore, such a non-halogen resin composition is suitably used for non-halogen insulated wires or non-halogen cables.

[Halogen-free resin composition]
A non-halogen resin composition has a base polymer, a metal hydroxide, and carbon black.
(base polymer)
The base polymer has polyolefin, maleic anhydride modified polyolefin and ethylene vinyl acetate copolymer.

(1) Polyolefin As a polyolefin, it has a melting point of 110°C or higher. The melting point can be determined by a differential scanning calorimetry (DSC) method. Oil resistance can be improved by using such a polyolefin having a melting point of 110° C. or higher.

In the oil resistance test, the test piece was immersed in IRM902 test oil heated to 100°C for 72 hours, and then the tensile properties were examined to determine how much the tensile properties after immersion changed from those before immersion. There is a way. For example, if the melting point is lower than 110° C., the crystals will melt during the oil resistance test, making it difficult to prevent oil from diffusing, and the rate of change in tensile properties will increase.

Polyolefins having a melting point of 110° C. or higher include low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, and polypropylene. However, high-density polyethylene has too high a degree of crystallinity and low elongation at break, and polypropylene easily collapses upon cross-linking such as electron beam irradiation. In order to obtain a balance of properties, it is preferable to use low-density polyethylene, and more preferable to use linear low-density polyethylene.

The amount of polyolefin to be added is 60 to 70 parts by mass with respect to 100 parts by mass of the base polymer. If the amount is less than 60 parts by mass, oil resistance is insufficient, and if it exceeds 70 parts by mass, sufficient elongation at break cannot be obtained. When using low-molecular-weight polyethylene, molecular entanglement disappears and elongation decreases. Therefore, it is preferable to use polyethylene having MFR (melt flow rate JIS K 7210, 190° C., 2.16 kg load) of 10 g/10 min or less.

(2) Maleic anhydride-modified polyolefin Maleic anhydride-modified polyolefin is a polyolefin modified with maleic anhydride.

Polyolefins that can be used as modifying materials include low-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butene-1 copolymer. Polymers, ethylene-α-olefins such as ethylene-hexene-1 copolymers and ethylene-octene-1 copolymers can be used. Among them, ethylene-butene-1 copolymer, ethylene-hexene-1 copolymer, and ethylene-octene-1 copolymer have few crystals and are excellent in Wyler acceptability, so they can be used as materials for maleic anhydride-modified polyolefin. is preferred.

The method of modifying polyolefin with maleic anhydride is not limited, and it can be obtained by a heat-only reaction. Maleic anhydride in the maleic anhydride-modified polyolefin may be graft-copolymerized or block-copolymerized.

The amount of the maleic anhydride-modified polyolefin to be added is 10 to 35 parts by mass with respect to 100 parts by mass of the base polymer. If it is less than 10 parts by mass, the required low-temperature properties cannot be satisfied, and if it is more than 35 parts by mass, the initial elongation at break is insufficient.

In order to obtain higher low-temperature properties, it is more preferable to add the maleic anhydride-modified polyolefin in an amount of 25 to 35 parts by mass with respect to 100 parts by mass of the base polymer.

(3) Ethylene-Vinyl Acetate Copolymer By using an ethylene-vinyl acetate copolymer as the base polymer, an endothermic reaction occurs due to deacetic acid during combustion, and flame retardancy can be improved. High flame retardance can be obtained by setting the amount of acetic acid (amount of CH ₃ COO—) in 100% of the base polymer to 2.3% by mass or more, and even higher flame resistance can be obtained by setting the amount to 6% by mass or more. Flammability can be obtained. In addition, when blending with polyolefin, if the viscosity difference is large, the dispersibility deteriorates and the low temperature characteristics deteriorate. It is preferred to use a vinyl copolymer.

(metal hydroxide)
A metal hydroxide is added to the base polymer. This metal hydroxide is a flame retardant. Examples of metal hydroxides that can be used include aluminum hydroxide, magnesium hydroxide, and calcium hydroxide. Among them, it is preferable to use aluminum hydroxide and magnesium hydroxide. The amount of heat absorbed during decomposition of calcium hydroxide is about 1000 J/g, while the amount of heat absorbed by aluminum hydroxide and magnesium hydroxide is 1500 to 1600 J/g, which is high. Therefore, flame retardancy is improved by adding aluminum hydroxide or magnesium hydroxide.

Furthermore, it is preferable to use magnesium hydroxide. Since magnesium hydroxide has a decomposition temperature higher than that of aluminum hydroxide, the moldability is improved.

The metal hydroxide can be surface-treated with a silane coupling agent, a titanate-based coupling agent, a fatty acid such as stearic acid, or the like in order to improve dispersibility and the like.

150 to 250 parts by mass of the metal hydroxide is added to 100 parts by mass of the base polymer. If it is less than 150 parts by mass, sufficient flame retardancy cannot be obtained, and if it is more than 250 parts by mass, elongation at break decreases.

(Carbon black)
Carbon black is added to the base polymer. Carbon black is a flame retardant aid. Although the type of carbon black to be added is not particularly limited, it is preferable to use FT or MT class carbon in consideration of elongation at break and the like.

A large amount of metal hydroxide must be added as a flame retardant in order to ensure a desired flame retardancy. However, the addition of flame retardants in large amounts may impair the mechanical properties of the composition. Therefore, carbon black is added as a flame retardant aid. The amount of carbon black added is 1 to 30 parts by mass with respect to 100 parts by mass of the base polymer. The flame retardancy can be improved with a larger amount of carbon black added, but if the amount is more than 30 parts by mass, the carbon black aggregates to form coarse particles, degrading initial elongation at break and low-temperature properties. More preferably, the amount of carbon black added is 2 to 30 parts by mass with respect to 100 parts by mass of the base polymer.

(Other additives)
In addition to the above materials, cross-linking agents, cross-linking aids, ultraviolet absorbers, light stabilizers, softeners, lubricants, coloring agents, reinforcing agents, surfactants, inorganic fillers, antioxidants, plasticizers, metal chelating agents, Blowing agents, compatibilizers, processing aids, stabilizers, and the like can be added.

As a flame retardant aid, a flame retardant aid other than the carbon black may be added. Flame retardant aids include phosphorous flame retardant aids such as red phosphorus and triazine flame retardant aids such as melamine cyanurate. Become. Any flame retardant auxiliary other than these can be applied, and examples thereof include clay, silica, zinc stannate, zinc borate, calcium borate, dolomide hydroxide, and silicone.

(Gel fraction)
The gel fraction is a method of confirming the degree of cross-linking of a polymer. A method for measuring the gel fraction will be described. First, a sample is weighed (W1) and immersed in xylene heated to 110° C. for 24 hours. After the immersion, it is left at 20° C. for 3 hours under atmospheric pressure, and vacuum-dried at 80° C. for 4 hours. The weight ratio ((W2/W1)×100, unit [%]) of the weight (W2) of the sample after this and the weight (W1) before immersion in xylene is defined as the gel fraction. If the gel fraction is less than 85%, it cannot be said that the oil resistance is sufficient.

Cross-linking treatment includes chemical cross-linking using organic peroxides, sulfur compounds, silanes, etc., irradiation cross-linking using electron beams, radiation, etc., and chemical cross-linking using other chemical reactions, and any cross-linking method can be applied. . Among them, irradiation crosslinking using an electron beam is more versatile than other irradiation crosslinking, and unlike chemical crosslinking, there is no risk of scorching during extrusion molding, so it is preferably used as the crosslinking treatment of the present embodiment.

[Insulated wire]
FIG. 1 is a cross-sectional view showing a configuration example of an insulated wire according to this embodiment. The insulated wire 11 shown in FIG. 1 has a conductor 11a, an insulating inner layer 11b formed around the conductor 11a, and an insulating outer layer 11c formed around the insulating inner layer 11b. Thus, the insulating layer covering the conductor 11a may have a two-layer structure of the insulating inner layer 11b and the insulating outer layer 11c.

As the conductor 11a, for example, a twisted wire in which a plurality of wires (metal wires) are twisted together can be used. As the element wire, for example, in addition to copper wire and copper alloy wire, aluminum wire, gold wire, silver wire, etc. can be used.

For example, polybutylene terephthalate or the like can be used as the insulating inner layer 11b. In addition, the inner layer material may optionally contain an antioxidant, a silane coupling agent including silicone gum, a flame retardant, a flame retardant aid, a cross-linking agent, a cross-linking aid, a cross-linking accelerator, and an anti-hydrolysis agent (e.g., polycarbodiimide compound), lubricants (e.g. fatty acid metal salts, amide-based lubricants), softeners, plasticizers, inorganic fillers, carbon black, compatibilizers, stabilizers, metal chelating agents, UV absorbers, light stabilizers, coloring Additives such as agents may be added. As the insulating inner layer 11b, a composition crosslinked by silane water crosslinking or electron beam irradiation may be used.

The non-halogen resin composition described above can be used for the insulating outer layer 11c.

Further, another resin composition containing a non-halogen flame retardant may be used as the insulating outer layer 11c. Even with non-halogen flame retardants, it is preferable not to add phosphorus flame retardants such as red phosphorus or triazine flame retardants such as melamine cyanurate. The polymer applied to the insulating outer layer 11c is not particularly limited as long as it is halogen-free. Examples thereof include polyolefins such as high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene, and ethylene-acrylate copolymer. Rubber materials are also applicable, ethylene-propylene copolymer rubber, ethylene-propylene-diene terpolymer rubber, acrylic rubber, ethylene-acrylate copolymer rubber, ethylene octene copolymer rubber, ethylene- Examples include vinyl acetate copolymer rubber, ethylene-butene-1 copolymer rubber, butadiene-styrene copolymer rubber, isobutylene-isoprene copolymer rubber, and block copolymer rubber having polystyrene blocks. Engineering plastics can also be applied, including polyethylene terephthalate, polybutylene terephthalate, polyphenylene ether, polycarbonate, polyamide, polyphenylene sulfide, polyether ether ketone, polyethylene naphthalate, polybutylene naphthalate, polyether sulfone, and the like. , these thermoplastic elastomers can also be used. The base polymer may be used alone or in a blend of two or more.

The resin composition composed of the above materials in the insulating outer layer 11c may optionally contain a cross-linking agent, a cross-linking aid, a flame retardant aid, an ultraviolet absorber, a light stabilizer, a softening agent, a lubricant, a coloring agent, a reinforcing agent, and a reinforcing agent. agents, surfactants, inorganic fillers, plasticizers, metal chelating agents, foaming agents, compatibilizers, processing aids, stabilizers and the like can be added.

Cross-linking should be performed from the viewpoint of oil resistance, and cross-linking treatments include chemical cross-linking using organic peroxides or silane compounds, irradiation cross-linking using electron beams, radiation, etc., and cross-linking using other chemical reactions. However, any cross-linking method is applicable.

By adopting such a two-layer structure, electrical insulation can be improved by the insulating inner layer 11b on the conductor 11a side, and flame retardancy and the like can be improved by the insulating outer layer 11c, which is the outermost layer.

In FIG. 1, the insulating layer covering the conductor 11a has a two-layer structure of the insulating inner layer 11b and the insulating outer layer 11c, but it may have a structure of three or more layers or a single layer. In any case, by using the non-halogen resin composition described above as the outermost layer, the properties of the non-halogen insulated wire can be improved.

[cable]
FIG. 2 is a cross-sectional view showing a configuration example of the cable of this embodiment. The cable 12 shown in FIG. 2 includes two twisted insulated wires 11 (twisted core, see FIG. 1), a separator 12b provided outside the twisted core, and a separator 12b provided so as to cover this separator. It has a shield braid 12c and a sheath (covering layer, covering layer) 12d covering the shield braid 12c. By using the non-halogen resin composition described above for the sheath 12d, the properties of the non-halogen cable can be improved. In addition, the number of insulated wires 11 may be one, or three or more. The material of the separator is not particularly limited, and it may be provided outside the shield braid.

The use of such insulated wires and cables is not limited, but they can be used, for example, as insulated wires or cables for railroad vehicles.

(Example)
EXAMPLES The non-halogen resin composition, the insulated wire and the cable of the present embodiment are described in more detail below using examples.

Using the non-halogen resin composition, insulated wires and cables were produced as follows.

(Non-halogen resin composition)
Non-halogen resin compositions were produced according to the formulations shown in Table 1 for Examples 1 to 11 and according to the formulations shown in Table 2 for Comparative Examples 1 to 9. The units of the compounding amounts in Tables 1 to 3 are parts by mass. That is, the compounding materials shown in Tables 1 and 2 were kneaded by a pressure kneader, extruded with a strand, cooled and pelletized. The mixing ratio of the non-halogen resin composition of each example and each comparative example will be described later in detail. Table 3 shows the details of other additives (6 parts by mass) to be described later.

(Production of insulated wires and cables)
An insulated wire was produced (see FIG. 1). Nineteen tin-plated copper conductors with a diameter of 0.18 mm were used as the conductors 11a. Polybutylene terephthalate (Mitsubishi Engineering-Plastics, Nova Duran 5026) was used as the insulating inner layer 11b. As the insulating outer layer 11c, polyethylene (Hi-Zex 5305E manufactured by Prime Polymer) 30 parts by mass, ethylene-ethyl acrylate-maleic anhydride terpolymer (Bondine LX4110 manufactured by Arkema) 30 parts by mass, maleic anhydride-modified ethylene- α-olefin (manufactured by Mitsui Chemicals, Tafuma MA7020) 10 parts by mass, ethylene-ethyl acrylate copolymer (manufactured by Japan Polyethylene, Rexpearl A1150) 30 parts by mass, magnesium hydroxide (manufactured by Kyowa Kagaku Co., Ltd., trade name: Kisuma 5L) 150 parts by mass were kneaded with a 14-inch open roll and pelletized with a granulator. A 40 mm extruder is used to perform two-layer extrusion on the outside of the conductor 11a so that the thickness of the insulating inner layer 11b is 0.1 mm, and the thickness of the insulating outer layer 11c is 0.16 mm. and an insulating outer layer 11c. The obtained insulated wire 11 was crosslinked by irradiation with an electron beam.

Next, a cable was produced using the insulated wire 11 (see FIG. 2). Two of the obtained insulated wires 11 are twisted to form a twisted core, and a 32 μm polyethylene terephthalate separator 12 b is wrapped thereon, and a 0.11 mm tin-plated copper conductor is used to increase the braid density. An 80% shield braid 12c was formed to form the core.

A composition shown in Tables 1 and 2 was extruded on the core with a 40 mm extruder to a thickness of 0.7 mm to form a sheath 12d. The sheath 12d of the obtained cable was irradiated with an electron beam at the dose shown in Tables 1 and 2 to crosslink the sheath 12d, thereby fabricating the cable 12.

(evaluation and judgment)
A tensile test was performed. The twisted core and the like were pulled out from the cable, and the tubular sheath was punched out with a No. 6 dumbbell to obtain a test piece. At room temperature (25° C.), the test piece was pulled at a displacement rate of 250 mm/min, and the load and elongation (Lb) until breakage were measured. The tensile strength (unit [MPa]) was calculated from the load. Also, the elongation at break ((Lb−La/La)×100[%]) was calculated from the initial length La and the elongation Lb. An elongation at break of 200% or more was evaluated as ⊚ (excellent), an elongation at break of 150% or more and less than 200% was evaluated as ◯ (good), and less than 150% was evaluated as x (improper).

A low temperature test was performed. The twisted core and the like were pulled out from the cable, and the tubular sheath was punched out with a No. 6 dumbbell to obtain a test piece. The test piece was held at −40° C., pulled at a displacement rate of 25 mm/min in an atmosphere of −40° C., and the elongation (L2) until breakage was measured. Low-temperature elongation ((L2/L1)×100[%]) was calculated from the initial length L1 and elongation L2. A low-temperature elongation of 50% or more was evaluated as ⊚ (excellent), 30% or more and less than 50% was evaluated as ◯ (good), and less than 30% was evaluated as x (improper).

An oil resistance test was performed. The twisted core and the like were pulled out from the cable, and the tubular sheath was punched out with a No. 6 dumbbell to obtain a test piece. After the test piece was immersed in IRM902 test oil heated to 70° C. for 168 hours, the test piece was pulled at a displacement rate of 250 mm/min, and the load and elongation until breakage were measured. From the tensile strength (A1) and breaking elongation (B1) of the test piece before immersion in the test oil, and the tensile strength (A2) and breaking elongation (B2) of the test piece after immersion in the test oil, oil resistance The rate of change in tensile strength ((A2/A1)×100[%]) and the rate of change in oil-resistant elongation at break ((B2/B1)×100[%]) were calculated. A drop in "tensile strength" or "elongation at break" after immersion was indicated as "- (minus)". If the oil resistance tensile strength change rate (tensile strength retention rate) was -30% or more, it was evaluated as ◯ (good), and if it was less than -30%, it was evaluated as x (improper). If the oil breaking elongation change rate (tensile elongation residual rate) was -30% or more, it was evaluated as ◯ (good), and if it was less than -30%, it was evaluated as x (improper).

A combustion test (flame retardancy test) was performed. A cable with a length of 600 mm was cut out as a test piece, held vertically, exposed to a flame for 60 seconds, and then the flame was removed. For those that did not self-digest, the test piece was changed and the same test was performed twice in succession. For those that did not self-extinguish all three times, the test piece was held at a 60° tilt, exposed to a flame for 60 seconds, and then the flame was removed. Those that did not self-extinguish even in this 60° inclined combustion test were evaluated as x (improper).

Gel fraction was measured. The sheath of the cable was cut and separated with a knife to obtain a test piece. A test piece was weighed (W1), immersed in xylene heated to 110° C. for 24 hours, left at 20° C. for 3 hours under atmospheric pressure, and vacuum-dried at 80° C. for 4 hours. The gel fraction was obtained from the weight ratio ((W2/W1)×100[%]) of the weight (W2) of the test piece after this and the weight (W1) of the test piece before immersion in xylene. Those having a gel fraction of 85% or more were evaluated as ⊚ (excellent).

As a comprehensive evaluation, in all the above evaluations (tensile test (breaking elongation), low temperature test (low temperature elongation), oil resistance test (oil resistance tensile strength change rate, oil resistance breaking elongation change rate), combustion test, gel fraction) ◎ Or, those with ○ were rated as ⊚ (excellent), those containing Δ were rated as ○ (good), and those containing x were rated as x (improper).

(Examples 1-3)
In the following description, PE indicates polyethylene and EVA indicates ethylene-vinyl acetate copolymer. In addition, maleic anhydride-modified polyolefin is indicated simply as "modified polyolefin" in the tables. Also, the content of acetic acid (CH ₃ COO-) in the ethylene-vinyl acetate copolymer relative to the base polymer is shown as "VA amount [% by mass]". This corresponds to the amount (g) of acetic acid (CH ₃ COO—) contained in 100 g of base polymer.

60 parts by mass of PE (SP1510 manufactured by Prime Polymer, melting point 117° C.), 15 parts by mass of EVA (Levaprene 600 manufactured by LANXESS, acetic acid content 60% by mass), 25 parts by mass of maleic anhydride-modified polyolefin (Tafuma MH5040 manufactured by Mitsui Chemicals) , 150 to 250 parts by mass of magnesium hydroxide (Kamishima Chemical Industry, Magshees S4) as a flame retardant, 10 parts by mass (Asahi Carbon, Asahi Thermal) as carbon black, and 6 parts by mass as other additives (see Table 3). The non-halogen resin composition prepared in this manner was used as a material for the sheath. In addition, pentaerythritol tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (Knox 1010) and (1,3,5-tris(3,5- Di-t-butyl-4-hydroxybenzyl)-s-triazine-2,4,6-(1H,3H,5H)trione) (AO-18) is an antioxidant and zinc stearate (SZ- P) is a lubricant and trimethylolpropane triacrylate) (TMPT) is a coagent.

Cables were fabricated and tested as described above. The sheath was crosslinked by 5 Mrad electron beam irradiation.

Table 1 shows the test results. In Examples 1 to 3, all the tests were evaluated as ⊚ or ◯, so the overall evaluation was ⊚.

(Examples 4-6)
PE (manufactured by Prime Polymer, SP1510, melting point 117° C.) 60 parts by mass, EVA (manufactured by DuPont Mitsui Chemicals, Evaflex 45LX, MFR 2.5 g/10 min, acetic acid content 46% by mass) 5 to 30 parts by mass, maleic anhydride-modified polyolefin (Tafuma MH5040, manufactured by Mitsui Chemicals) 10 to 35 parts by mass, magnesium hydroxide (Kamishima Chemical Industry, Magshees S4) 180 parts by mass as a flame retardant, (Asahi Carbon, Asahi Thermal) 10 parts by mass as carbon black, other additives A non-halogen resin composition kneaded with 6 parts by mass of as a material for the sheath was used.

Cables were fabricated and tested as described above. The sheath was crosslinked by 5 Mrad electron beam irradiation.

Table 1 shows the test results. In Examples 4 to 6, all the evaluations were ⊚ or ◯, so the comprehensive evaluation was ⊚. However, in Example 5, the low-temperature characteristics were inferior to those of the other examples.

(Example 7)
PE (made by Prime Polymer, SP1510, melting point 117 ° C.) 60 parts by mass, EVA (manufactured by DuPont Mitsui Chemicals, Evaflex 45X, MFR 100 g / 10 min, acetic acid content 46% by mass) 15 parts by mass, maleic anhydride-modified polyolefin (manufactured by Mitsui Chemicals , Tafuma MH5040) 25 parts by mass, 180 parts by mass of magnesium hydroxide (Kamishima Kagaku Kogyo, Magshees S4) as a flame retardant, 10 parts by mass of carbon black (Asahi Carbon, Asahi Thermal), and 6 parts by mass as other additives. The non-halogen resin composition prepared in this manner was used as a material for the sheath.

Cables were fabricated and tested as described above. The sheath was crosslinked by 5 Mrad electron beam irradiation.

Table 1 shows the test results. In Example 7, the low-temperature characteristics were slightly inferior to those in Example 6, but all the evaluations were ⊚ or ◯, so the overall evaluation was ⊚.

(Examples 8-10)
PE (made by Prime Polymer, SP1510, melting point 117° C.) 60 to 70 parts by mass, EVA (made by Lanxess, Levaprene 600, acetic acid content 60% by mass) 5 to 10 parts by mass, maleic anhydride-modified polyolefin (manufactured by Mitsui Chemicals, Tafuma MH5040 ) 25 to 30 parts by mass, 180 parts by mass of magnesium hydroxide (Kamishima Chemical Industry, Magshees S4) as a flame retardant, 1 to 30 parts by mass of carbon black (Asahi Carbon, Asahi Thermal), and 6 parts by mass as other additives. The kneaded non-halogen resin composition was used as a sheath material.

Cables were fabricated and tested as described above. The sheath was crosslinked by 5 Mrad electron beam irradiation.

Table 1 shows the test results. In Examples 8 and 10, all the evaluations were ⊚ or ◯, so the overall evaluation was ⊚. In Example 9, since the combustion test was Δ, the overall evaluation was ◯.

(Example 11)
PE (made by Prime Polymer, SP1510, melting point 117 ° C.) 60 parts by mass, EVA (manufactured by DuPont Mitsui Chemicals, Evaflex 45X, MFR 100 g / 10 min, acetic acid content 46% by mass) 15 parts by mass, maleic anhydride-modified polyolefin (manufactured by Mitsui Chemicals , Tafuma MH5040) 25 parts by mass, 180 parts by mass of magnesium hydroxide (Kamishima Kagaku Kogyo, Magsees S4) as a flame retardant, 2 parts by mass of carbon black (Asahi Carbon, Asahi Thermal), and 6 parts by mass as other additives. The non-halogen resin composition prepared in this manner was used as a material for the sheath.

Cables were fabricated and tested as described above. The sheath was crosslinked by 5 Mrad electron beam irradiation.

Table 1 shows the test results. In Example 11, the flame retardancy was slightly inferior to that of Example 7, but all the evaluations were ⊚ or ◯, so the overall evaluation was ⊚.

(Comparative example 1)
60 parts by mass of PE (made by Prime Polymer, SP1510, melting point 117°C), 40 parts by mass of maleic anhydride-modified polyolefin (manufactured by Mitsui Chemicals, Tafuma MH5040), and 180 parts by mass of magnesium hydroxide (Kamishima Chemical Co., Ltd., Magshees S4) as a flame retardant. , 10 parts by mass of carbon black (Asahi Carbon, Asahi Thermal) and 6 parts by mass of other additives were kneaded to form a non-halogen resin composition, which was used as a sheath material.

Cables were fabricated and tested as described above. The sheath was crosslinked by 5 Mrad electron beam irradiation.

Table 2 shows the test results. In Comparative Example 1, the addition amount of the maleic anhydride-modified polyolefin was large, and the initial elongation at break was less than 150%, resulting in x, so the overall evaluation was x.

(Comparative example 2)
55 parts by mass of PE (SP1510 manufactured by Prime Polymer, melting point 117° C.), 5 parts by mass of EVA (Levaprene 600 manufactured by Lanxess, acetic acid content 60% by mass), 40 parts by mass of maleic anhydride-modified polyolefin (Tafuma MH5040 manufactured by Mitsui Chemicals) A non-halogen resin composition in which 180 parts by mass of magnesium hydroxide (Kamijima Chemical Industry, Magshees S4) as a flame retardant, 10 parts by mass of carbon black (Asahi Carbon, Asahi Thermal), and 6 parts by mass as other additives are kneaded. It was used as a sheath material.

Cables were fabricated and tested as described above. The sheath was crosslinked by 5 Mrad electron beam irradiation.

Table 2 shows the test results. In Comparative Example 2, the amount of polyethylene was small, and the rate of change in oil resistance tensile strength was less than -30%, resulting in x, so the overall evaluation was x.

(Comparative Example 3)
In the coating layer, PE (manufactured by Prime Polymer, SP1510, melting point 117 ° C.) 75 parts by mass, EVA (Lanxess, Levaprene 600, acetic acid content 60% by mass) 5 parts by mass, maleic anhydride-modified polyolefin (manufactured by Mitsui Chemicals, Tafuma MH5040 ) 20 parts by mass, 180 parts by mass of magnesium hydroxide (Kamishima Chemical Co., Ltd., Magshees S4) as a flame retardant, 10 parts by mass of carbon black (Asahi Carbon, Asahi Thermal), and 6 parts by mass as other additives, non-halogen A resin composition was used as the sheath material.

Cables were fabricated and tested as described above. The sheath was crosslinked by 5 Mrad electron beam irradiation.

Table 2 shows the test results. In Comparative Example 3, the amount of polyethylene was large, and the initial elongation at break was less than 150%, resulting in x, so the overall evaluation was x.

(Comparative Example 4)
PE (Japan Polyethylene, Novatec ZF33Tml08°C) 60 parts by mass, EVA (Lanxess Levaprene 600, acetic acid content 60% by mass) 15 parts by mass, maleic anhydride-modified polyolefin (Tafuma MH5040 by Mitsui Chemicals) 25 parts by mass, flame retardant 180 parts by mass of magnesium hydroxide (Kamishima Chemical Co., Magshees S4) as a material, 10 parts by mass of carbon black (Asahi Carbon, Asahi Thermal), and 6 parts by mass of other additives are kneaded. used as

Cables were fabricated and tested as described above. The sheath was crosslinked by 5 Mrad electron beam irradiation.

Table 2 shows the test results. In Comparative Example 4, the melting point of PE was lower than 110° C., and the oil resistance tensile strength retention rate was lower than -30%, which was rated as x. Therefore, the overall evaluation was x.

(Comparative Example 5)
60 parts by mass of PE (SP1510 manufactured by Prime Polymer, melting point 117° C.), 35 parts by mass of EVA (Levaprene 600 manufactured by LANXESS, acetic acid content 60% by mass), 5 parts by mass of maleic anhydride-modified polyolefin (Tafuma MH5040 manufactured by Mitsui Chemicals) A non-halogen resin composition in which 180 parts by mass of magnesium hydroxide (Kamijima Chemical Industry, Magshees S4) as a flame retardant, 10 parts by mass of carbon black (Asahi Carbon, Asahi Thermal), and 6 parts by mass as other additives are kneaded. It was used as a sheath material.

Cables were fabricated and tested as described above. The sheath was crosslinked by 5 Mrad electron beam irradiation.

Table 2 shows the test results. In Comparative Example 5, the amount of maleic anhydride-modified polyolefin was small, and the elongation in the low-temperature test was less than 30%, resulting in x, so the overall evaluation was x.

(Comparative Example 6)
60 parts by mass of PE (SP1510 manufactured by Prime Polymer, melting point 117° C.), 15 parts by mass of EVA (Levaprene 600 manufactured by LANXESS, acetic acid content 60% by mass), 25 parts by mass of maleic anhydride-modified polyolefin (Tafuma MH5040 manufactured by Mitsui Chemicals) A non-halogen resin composition in which 260 parts by mass of magnesium hydroxide (Kamishima Chemical Co., Ltd., Magshees S4) as a flame retardant, 10 parts by mass of carbon black (Asahi Carbon, Asahi Thermal), and 6 parts by mass as other additives are kneaded. It was used as a sheath material.

Cables were fabricated and tested as described above. The sheath was crosslinked by 5 Mrad electron beam irradiation.

Table 2 shows the test results. In Comparative Example 6, the amount of the flame retardant was large, and the initial elongation at break and the elongation in the low temperature test were x, so the overall evaluation was x.

(Comparative Example 7)
60 parts by mass of PE (SP1510 manufactured by Prime Polymer, melting point 117° C.), 15 parts by mass of EVA (Levaprene 600 manufactured by LANXESS, acetic acid content 60% by mass), 25 parts by mass of maleic anhydride-modified polyolefin (Tafuma MH5040 manufactured by Mitsui Chemicals) A non-halogen resin composition in which 140 parts by mass of magnesium hydroxide (Kamishima Kagaku Kogyo, Magshees S4) as a flame retardant, 10 parts by mass of carbon black (Asahi Carbon, Asahi Thermal), and 6 parts by mass as other additives are kneaded. It was used as a sheath material.

Cables were fabricated and tested as described above. The sheath was crosslinked by 5 Mrad electron beam irradiation.

Table 2 shows the test results. In Comparative Example 7, the amount of the flame retardant was small, and the combustion test was x, so the overall evaluation was x.

(Comparative Example 8)
60 parts by mass of PE (SP1510 manufactured by Prime Polymer, melting point 117° C.), 15 parts by mass of EVA (Levaprene 600 manufactured by LANXESS, acetic acid content 60% by mass), 25 parts by mass of maleic anhydride-modified polyolefin (Tafuma MH5040 manufactured by Mitsui Chemicals) A non-halogen resin composition in which 180 parts by mass of magnesium hydroxide (Kamishima Kagaku Kogyo, Magshees S4) as a flame retardant, 35 parts by mass of carbon black (Asahi Carbon, Asahi Thermal), and 6 parts by mass as other additives are kneaded. It was used as a sheath material.

Cables were fabricated and tested as described above. The sheath was crosslinked by 5 Mrad electron beam irradiation.

Table 2 shows the test results. In Comparative Example 8, the amount of carbon black was large, and the initial elongation at break and the elongation in the low temperature test were x, so the overall evaluation was x.

(Comparative Example 9)
60 parts by mass of PE (SP1510 manufactured by Prime Polymer, melting point 117° C.), 15 parts by mass of EVA (Levaprene 600 manufactured by LANXESS, acetic acid content 60% by mass), 25 parts by mass of maleic anhydride-modified polyolefin (Tafuma MH5040 manufactured by Mitsui Chemicals) A non-halogen resin composition in which 180 parts by mass of magnesium hydroxide (Kamijima Chemical Industry, Magshees S4) as a flame retardant, 10 parts by mass of carbon black (Asahi Carbon, Asahi Thermal), and 6 parts by mass as other additives are kneaded. It was used as a sheath material.

Cables were fabricated and tested as described above. The sheath was crosslinked by 3 Mrad electron beam irradiation.

Table 2 shows the test results. In Comparative Example 9, the measurement result of the gel fraction was 80%, which was below 85%. In addition, since the rate of change in tensile strength in oil resistance was less than -30%, it was rated as x, so the overall evaluation was x.

(Discussion)
The following matters are considered from the above examples and comparative examples.

As the base polymer, it is preferable to use a polyolefin such as polyethylene, a maleic anhydride-modified polyolefin, and an ethylene-vinyl acetate copolymer. parts, preferably 5 to 30 parts by mass.

If the amount of polyolefin (polyethylene) is less than 60 parts by mass, oil resistance is insufficient (see Comparative Example 2), and if it exceeds 70 parts by mass, sufficient elongation at break cannot be obtained (see Comparative Example 3). Further, when the melting point of polyolefin (polyethylene) is less than 110° C., sufficient oil resistance cannot be obtained (see Comparative Example 4).

If the maleic anhydride-modified polyolefin is less than 10 parts by mass, the necessary low-temperature properties cannot be satisfied (see Comparative Example 5), and if it exceeds 35 parts by mass, the initial elongation at break is insufficient (see Comparative Example 1). .

Further, in order to obtain higher low-temperature properties, it is more preferable to add the maleic anhydride-modified polyolefin in an amount of 25 to 35 parts by mass with respect to 100 parts by mass of the base polymer (see Example 5).

Also, the ethylene-vinyl acetate copolymer is preferably 5 to 30 parts by mass (see Comparative Examples 1 and 5). High flame retardancy can be obtained by setting the amount of acetic acid (the amount of CH ₃ COO—) in 100% of the base polymer to 2.3% by mass or more (see Example 4, etc.), and 6% by mass or more. Further higher flame retardancy can be obtained by setting it as.

Furthermore, it is preferable to add the metal hydroxide at a ratio of 150 to 250 parts by mass with respect to 100 parts by mass of the base polymer. If it is less than 150 parts by mass, sufficient flame retardancy cannot be obtained (see Comparative Example 7), and if it is more than 250 parts by mass, elongation at break and the like will decrease (see Comparative Example 6).

Further, it is preferable to add carbon black in a proportion of 1 to 30 parts by mass with respect to 100 parts by mass of the base polymer. When the amount is more than 30 parts by mass, coarse particles are generated due to aggregation of carbon black, and the initial elongation at break and low-temperature properties are lowered (see Comparative Example 8).

Moreover, it is preferable that the non-halogen resin composition has a gel fraction of 85% or more after cross-linking. If the gel fraction is less than 85%, it cannot be said that the oil resistance is sufficient (see Comparative Example 9).

The present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the scope of the invention. For example, in the above examples, the sheath was explained as an example, but the composition of the above examples may be used for the outermost layer of the insulated wire.

11 Insulated wire 11a Conductor 11b Inner insulation layer 11c Outer insulation layer 12 Cable 12b Separator 12c Shield braid 12d Sheath

Claims (6)

An electric wire comprising a conductor and an insulating layer covering the conductor and formed from a non-halogen resin composition,
The non-halogen resin composition is a cross-linked non-halogen resin composition containing a base polymer, a metal hydroxide and carbon black,
The base polymer contains 60 to 70 parts by mass of polyolefin, 10 to 35 parts by mass of maleic anhydride-modified polyolefin, and 5 to 30 parts by mass of an ethylene-vinyl acetate copolymer having an MFR of 10 g/10 min or less. ,
The metal hydroxide is contained in a ratio of 150 to 250 parts by mass with respect to 100 parts by mass of the base polymer,
The carbon black is contained in a ratio of 1 to 30 parts by mass with respect to 100 parts by mass of the base polymer,
The melting point of the polyolefin is 110° C. or higher,
the content of acetic acid (CH ₃ COO-) in the ethylene-vinyl acetate copolymer is 6% by mass or more relative to the base polymer;
An electric wire having a gel fraction of 85% or more. In the electric wire according to claim 1,
The electric wire, wherein the addition amount of the maleic anhydride-modified polyolefin of the base polymer is 25 to 35 parts by mass. In the electric wire according to claim 1,
The electric wire, wherein the polyolefin is polyethylene. A cable comprising an insulated wire and a jacket layer covering the insulated wire and formed from a non-halogen resin composition,
The non-halogen resin composition is a cross-linked non-halogen resin composition containing a base polymer, a metal hydroxide and carbon black,
The base polymer contains 60 to 70 parts by mass of polyolefin, 10 to 35 parts by mass of maleic anhydride-modified polyolefin, and 5 to 30 parts by mass of an ethylene-vinyl acetate copolymer having an MFR of 10 g/10 min or less. ,
The metal hydroxide is contained in a ratio of 150 to 250 parts by mass with respect to 100 parts by mass of the base polymer,
The carbon black is contained in a ratio of 1 to 30 parts by mass with respect to 100 parts by mass of the base polymer,
The melting point of the polyolefin is 110° C. or higher,
the content of acetic acid (CH ₃ COO-) in the ethylene-vinyl acetate copolymer is 6% by mass or more relative to the base polymer;
A cable having a gel fraction of 85% or more. A cable according to claim 4,
The cable, wherein the addition amount of the maleic anhydride-modified polyolefin of the base polymer is 25 to 35 parts by mass. A cable according to claim 4,
The cable, wherein the polyolefin is polyethylene.

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