JP2016037515A - Phosphorus-free non-halogen flame-retardant resin composition and wire and cable using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a phosphorus-free non-halogen flame-retardant resin composition having excellent mechanical strength, flexibility, heat resistance and insulation properties; and an electric wire and a cable using the same.SOLUTION: There is provided a phosphorus-free non-halogen flame retardant resin composition which comprises a base polymer (A) which is obtained by polymerizing ethylene and an α-olefin having 3 to 8 carbon atoms using a metallocene catalyst and is composed mainly of an ethylene-α-olefin copolymer (a1) having a heat of fusion of 60 J/g or less as measured by a differential scanning calorimeter and has a mechanical strength, such as, a tensile strength of 7 MPa or more and an elongation of 350% or more, flexibility, such as, a 100% modulus of 6 MPa or less, heat resistance, such as, a tensile strength residual rate of 80% or more and an elongation rate of 80% or more after a heat aging test at 150°C for 96 hours and a volume resistivity of 1×10Ω cm or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a phosphorus-free non-halogen flame retardant resin composition, and an electric wire and cable using the same.

  In recent years, non-halogen flame retardant wires and cables that do not use polyvinyl chloride or halogen-based flame retardants are rapidly spreading as eco wires and cables. In these non-halogen flame retardant electric wires and cables, a resin composition in which a large amount of non-halogen flame retardant such as magnesium hydroxide is mixed with polyolefin is generally used as an insulating layer of the electric wire (for example, patent document). 1).

  However, using non-halogen flame retardants such as magnesium hydroxide, in order to achieve high flame retardancy in vertical tray combustion tests that pass overseas flame retardant standards (EN, DIN, BS), A large amount of non-halogen flame retardant needs to be mixed, and therefore mechanical strength such as tensile strength and elongation tends to be greatly reduced.

  In order to suppress the decrease in mechanical strength, there is a method of reducing the amount of non-halogen flame retardant using a flame retardant aid such as red phosphorus, but red phosphorus generates harmful phosphine during combustion or phosphoric acid during disposal. Concerns about generating water and polluting groundwater veins are pointed out. Therefore, a phosphorus-free non-halogen flame retardant resin composition containing no phosphorus as a flame retardant aid is desired.

Japanese Patent Laid-Open No. 10-287777

  The phosphorus-free non-halogen flame retardant resin composition is desired to have excellent mechanical strength, flexibility and heat resistance as well as flame retardancy. Furthermore, it is desired that the insulating property is also excellent.

  An object of the present invention is to provide a phosphorus-free non-halogen flame-retardant resin composition having excellent flame retardancy, mechanical strength, flexibility and heat resistance, and excellent insulation, and an electric wire and cable using the same. That is.

According to a first aspect of the invention,
The main component is an ethylene-α olefin copolymer (a1) in which ethylene and an α-olefin having 3 to 8 carbon atoms are polymerized by a metallocene catalyst, and the heat of fusion measured by a differential scanning calorimeter is in the range of 60 J / g or less. Containing a base polymer (A)
Mechanical strength having a tensile strength of 7 MPa or more and an elongation of 350% or more;
Flexibility with 100% modulus of 6 MPa or less;
Heat resistance with a tensile strength residual rate of 80% or more and an elongation residual rate of 80% or more after a heat aging test at 150 ° C. for 96 hours,
A phosphorus-free non-halogen flame retardant resin composition having an insulating property with a volume resistivity of 1 × 10 ¹⁴ Ω · cm or more is provided.

According to a second aspect of the invention,
Conductors,
A coating layer covering the outer periphery of the conductor,
The said coating layer provides the electric wire currently formed with the phosphorus-free non-halogen flame retardant resin composition of the 1st aspect.

According to a third aspect of the invention,
Electric wires,
A coating layer covering the outer periphery of the electric wire,
A cable is provided in which the coating layer is formed of the phosphorus-free non-halogen flame retardant resin composition of the first aspect.

  According to the present invention, a phosphorus-free non-halogen flame-retardant resin composition excellent in flame retardancy, mechanical strength, flexibility and heat resistance, and excellent in insulation properties, and an electric wire or cable using the same can be obtained. .

It is the schematic which shows the cross section of the electric wire which concerns on one Embodiment of this invention. It is the schematic which shows the cross section of the cable which concerns on one Embodiment of this invention.

  As described above, the phosphorus-free non-halogen flame retardant resin composition needs to contain a large amount of a flame retardant from the viewpoint of obtaining high flame retardancy. However, when a flame retardant is contained in a large amount, properties such as mechanical strength, flexibility, heat resistance, and insulation properties are deteriorated.

  Accordingly, the present inventors have studied a base polymer used in a phosphorus-free non-halogen flame retardant resin composition in order to suppress deterioration of characteristics due to a large amount of flame retardant and to improve various characteristics. As a result, attention was focused on an ethylene-α olefin copolymer polymerized with a metallocene catalyst as a base polymer. This ethylene-α olefin copolymer is polymerized by a metallocene catalyst so that the molecular weight distribution becomes narrow, and is excellent in mechanical strength and flexibility. Therefore, even when a large amount of flame retardant is contained, the mechanical strength and flexibility can be kept high. In addition, the volume resistivity is small and the insulation is excellent.

  However, it is difficult to maintain high heat resistance, and there is room for improvement. In this regard, the present inventors have further studied by changing the type of ethylene-α olefin copolymer, and if a heat of fusion exceeds 60 J / g, the heat resistance may be significantly reduced. I understood. Therefore, by using an ethylene-α-olefin copolymer having a heat of fusion in the range of 60 J / g or less as a main component of the base polymer, in addition to flame retardancy, mechanical strength, flexibility and insulation, It has been found that a phosphorus-free non-halogen flame retardant resin composition having excellent properties can be obtained.

  The present invention has been made based on the above findings.

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

(1) Phosphorus-free non-halogen flame-retardant resin composition The phosphorus-free non-halogen flame-retardant resin composition according to this embodiment is obtained by polymerizing ethylene and an α-olefin having 3 to 8 carbon atoms with a metallocene catalyst, and performing differential scanning. It contains a base polymer (A) whose main component is an ethylene-α olefin copolymer (a1) having a heat of fusion measured by a calorimeter in the range of 60 J / g or less, and has an elongation of 7 MPa or more. Mechanical strength of 350% or more, flexibility of 100% modulus of 6 MPa or less, residual tensile strength after heat aging test at 150 ° C. for 96 hours, 80% or more, and residual elongation of 80% or more Heat resistance and insulation having a volume resistivity of 1 × 10 ¹⁴ Ω · cm or more.

[Base polymer (A)]
The base polymer (A) contains an ethylene-α olefin copolymer (a1) as a main component.

(Ethylene-α olefin copolymer (a1))
The ethylene-α-olefin copolymer (a1) has a heat of fusion (hereinafter, also simply referred to as “heat of fusion”) measured by a differential scanning calorimeter in the range of 60 J / g or less. In this embodiment, the heat of fusion is calculated from the endothermic peak area in the melting endothermic peak obtained when the polymer is heated from −50 ° C. to 200 ° C. at a temperature rising rate of 10 ° C./min. Is.

  The ethylene-α-olefin copolymer (a1) is obtained by polymerizing ethylene and an α-olefin having 3 to 8 carbon atoms so that the molecular weight distribution is narrowed by a metallocene catalyst. As an ethylene-alpha olefin copolymer (a1), ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-octene copolymer, etc. can be used, for example. Examples of the α-olefin having 3 to 8 carbon atoms include propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene and the like. Among these, 1-butene and 1-octene are preferable.

  Since the ethylene-α-olefin copolymer (a1) is polymerized with a metallocene catalyst so that the molecular weight distribution is narrowed, it is excellent in mechanical strength and flexibility. In addition, the volume resistivity is small and the insulation is excellent. Furthermore, since the heat of fusion is in the range of 60 J / g or less, even when a large amount of flame retardant is added, it is possible to suppress a decrease in heat resistance due to a large amount of flame retardant and maintain high heat resistance. it can. Therefore, by using the base polymer (A) whose main component is the ethylene-α olefin copolymer (a1) having a heat of fusion in the range of 60 J / g or less in the phosphorus-free non-halogen flame retardant resin composition, Good characteristics such as mechanical strength, flexibility and heat resistance can be obtained.

The high heat resistance can be maintained by using the ethylene-α olefin copolymer (a1) as follows.
Generally, an ethylene-α olefin copolymer has a crystalline region and an amorphous region in its chemical structure. When a flame retardant is added to such an ethylene-α-olefin copolymer, the flame retardant is not dispersed in the crystalline region but dispersed in the amorphous region. If a small amount of flame retardant is added, the density of the flame retardant dispersed in the amorphous region is relatively low, so the heat resistance inherent to the ethylene-α-olefin copolymer is unlikely to be lowered and maintained high. become. On the other hand, when a large amount of the flame retardant is added, the density of the flame retardant in the amorphous region increases, so that the heat resistance is considered to be impaired.
In the present embodiment, the heat of fusion of the ethylene-α olefin copolymer indicates the amount of heat necessary to melt the crystal region contained in the chemical structure, and the magnitude of the heat of fusion is the ratio of the crystal region. It becomes an index. Specifically, it shows that the smaller the heat of fusion, the smaller the proportion of the crystalline region and the larger the proportion of the amorphous region.
In the ethylene-α olefin copolymer, when the heat of fusion exceeds 60 J / g, the proportion of the crystalline region increases and the proportion of the amorphous region in which the flame retardant disperses decreases. Therefore, when a large amount of the flame retardant is added, the density of the flame retardant in the amorphous region becomes excessively large, and the heat resistance is significantly lowered. On the other hand, when the heat of fusion is 60 J / g or less, the ratio of the amorphous region becomes relatively large. Therefore, even if a large amount of flame retardant is added, the density of the flame retardant in the amorphous region is suppressed from being excessively increased, and the heat resistance is suppressed from decreasing.

  Since ethylene-alpha olefin copolymer (a1) can ensure the tolerance of heat resistance, so that the amount of heat of fusion is low, Preferably it is 40 J / g or less, More preferably, it is 30 J / g or less. The lower limit of the heat of fusion is not particularly limited, and may be 0 J / g.

  The base polymer (A) contains the ethylene-α-olefin copolymer (a1) as a main component, but the main component is the content of the ethylene-α-olefin copolymer (a1), and the base polymer (A) is 100 masses. It is preferably 60 parts by mass or more, more preferably 70 parts by mass or more with respect to parts. With such a content, the heat of fusion of the base polymer (A) can be made close to the heat of fusion of the ethylene-α-olefin copolymer (a1). Thereby, even if it is a case where other polymers other than ethylene-alpha olefin copolymer (a1) are contained in a base polymer (A), a heat resistant fall can be suppressed.

(Other polymers)
In the phosphorus-free non-halogen flame retardant resin composition according to the present embodiment, from the viewpoint of obtaining better characteristics, the base polymer (A) is ethylene-acetic acid containing 40% by mass or more of vinyl acetate as another polymer. It is preferable to contain a vinyl copolymer (a2) (hereinafter also simply referred to as “EVA (a2)”) or a maleic acid-modified ethylene copolymer (a3).

  EVA (a2) contains vinyl acetate, and suppresses combustion by causing an endothermic reaction by deacetic acid when the phosphorus-free non-halogen flame retardant resin composition burns and thermally decomposes. That is, EVA (a2) contributes to improvement in flame retardancy. When the amount of vinyl acetate is less than 40% by mass, the endothermic amount is reduced, so that it becomes difficult to obtain sufficient flame retardancy.

  EVA (a2) preferably has a melt flow rate (MFR) of 50 g / 10 min or more. In a phosphorus-free non-halogen flame retardant resin composition, when a large amount of a flame retardant is added, the viscosity increases and the extrusion moldability deteriorates, so that the appearance (extruded appearance) when extruded may be poor. . However, since EVA (a2) of a predetermined MFR functions as a wax, the inclusion of this EVA (a2) decreases the viscosity of the phosphorus-free non-halogen flame retardant resin composition and improves the extrusion moldability. be able to.

  EVA (a2) is preferably contained in an amount of 5 to 30 parts by mass in 100 parts by mass of the base polymer (A). If it is less than 5 parts by mass, there is a possibility that the effect of improving flame retardancy and extrusion moldability by EVA (a2) may not be obtained. If it exceeds 30 parts by mass, the viscosity of the phosphorus-free non-halogen flame retardant resin composition may be excessively lowered and the mechanical strength may be lowered.

  The maleic acid-modified ethylene copolymer (a3) is a copolymer of ethylene and an α-olefin having 3 to 8 carbon atoms modified with maleic anhydride. The maleic acid-modified ethylene copolymer (a3) improves the adhesion at the interface between the above-mentioned ethylene-α olefin copolymer (a1) or EVA (a2) and a flame retardant described later, thereby making it phosphorus-free. Improve the mechanical strength of the non-halogen flame retardant resin composition. Furthermore, it contributes also to suppressing the fall of heat resistance by improving the adhesiveness of an interface. As the maleic acid-modified ethylene copolymer (a3), a material obtained by modifying the above-described copolymer of ethylene and an α-olefin having 3 to 8 carbon atoms with maleic anhydride can be used.

  The maleic acid-modified ethylene copolymer (a3) is preferably contained in an amount of 5 parts by mass or more in 100 parts by mass of the base polymer (A). If it is less than 5 parts by mass, the adhesion between the ethylene-α-olefin copolymer (a1) or EVA (a2) and the flame retardant becomes weak, and the mechanical strength and heat resistance may be reduced. In addition, the upper limit of content of a maleic acid modification ethylene copolymer (a3) is a quantity which is not too much in a base polymer (A), for example, 30 mass parts.

  From the viewpoint of improving the heat resistance of the phosphorus-free non-halogen flame retardant resin composition, the heat of fusion of EVA (a2) or maleic acid-modified ethylene copolymer (a3) is the same as that of the ethylene-α olefin copolymer. Like (a1), it is preferable that it is low. Specifically, the heat of fusion of EVA (a2) is preferably 10 J / g or less, more preferably 0 J / g. The amount of heat of fusion of the maleic acid-modified ethylene copolymer (a3) is preferably 30 J / g or less, more preferably 20 J / g or less. According to such EVA (a2) and maleic acid-modified ethylene copolymer (a3), heat resistance can be reduced because it can be reduced to 60 J / g or less without increasing the total heat of fusion of the base polymer (A). Can be suppressed.

[Non-halogen flame retardant (B)]
The phosphorus-free non-halogen flame retardant resin composition according to the present embodiment contains a non-halogen flame retardant (B) as a flame retardant from the viewpoint of improving flame retardancy. As the non-halogen flame retardant (B), metal hydroxides such as aluminum hydroxide and magnesium hydroxide can be preferably used. These preferably have a surface treated with a fatty acid or silane, and more preferably a surface treated with a fatty acid. According to the fatty acid treatment or the silane treatment, it is possible to improve the mechanical strength by improving the adhesion between the non-halogen flame retardant (B) and the base polymer (A). In particular, according to the fatty acid treatment, the adhesiveness can be improved moderately as compared with the silane treatment, so that the mechanical strength can be improved without impairing flexibility.

  The halogen-free flame retardant (B) is preferably added in such an amount that the mechanical strength, flexibility, heat resistance, and insulation properties are good in addition to the flame retardancy. The content of the non-halogen flame retardant (B) is preferably 100 parts by mass or more and 250 parts by mass or less with respect to 100 parts by mass of the base polymer (A). If the amount is less than 100 parts by mass, the flame retardancy may be insufficient. If the amount exceeds 250 parts by mass, the mechanical strength (tensile strength and elongation) is greatly reduced, and the flexibility (100% modulus) is also reduced. There is a fear. Moreover, when it exceeds 250 mass parts, there exists a possibility that heat resistance and insulation may also fall.

  In addition to the above components, various additives such as other polymers, inorganic fillers, stabilizers, antioxidants, plasticizers and lubricants can be blended in the phosphorus-free non-halogen flame retardant resin composition. It is.

(2) Electric wire Next, the case of the electric wire as shown in FIG. 1 is demonstrated as an example of the structure produced using the above-mentioned phosphorus-free non-halogen flame-retardant resin composition. FIG. 1 is a schematic view showing a cross section of an electric wire according to an embodiment of the present invention.

As shown in FIG. 1, the electric wire 10 includes a conductor 1 and a coating layer (insulating layer) 2 that covers the outside of the conductor 1.
As the conductor 1, in addition to a commonly used metal wire, for example, a copper wire or a copper alloy wire, an aluminum wire, a gold wire, a silver wire, or the like can be used. Moreover, you may use what gave metal plating, such as tin and nickel, to the outer periphery of a metal wire. Further, a collective stranded conductor obtained by twisting metal wires can be used.
The insulating layer 2 is formed from the above phosphorus-free non-halogen flame retardant resin composition. The insulating layer 2 is formed by extrusion-coating a phosphorus-free non-halogen flame retardant resin composition on the outer periphery of the conductor 1. The insulating layer 2 is preferably cross-linked from the viewpoint of improving mechanical properties. This crosslinking method is not particularly limited, and conventionally known methods such as organic peroxide crosslinking, silane crosslinking, and radiation crosslinking can be used.

(3) Cable Next, the case of a cable as shown in FIG. 2 is demonstrated as an example of the structure produced using the above-mentioned phosphorus-free non-halogen flame retardant resin composition. FIG. 2 is a schematic view showing a cross section of a cable according to an embodiment of the present invention.

As shown in FIG. 2, the cable 11 is configured by a plurality of wires 10 bundled, an interposition 3, and a coating layer (sheath) 4 that covers the outside of the electric wire 10 (via the interposition 3).
The sheath 4 is formed by extrusion-coating the above-described phosphorus-free non-halogen flame retardant resin composition on the outer periphery of the interposition 3. The sheath 4 is preferably cross-linked.

<Effects According to One Embodiment of the Present Invention>
According to the present embodiment, the following one or more effects are achieved.

(A) According to this embodiment, an ethylene-α olefin copolymer (a1) polymerized by a metallocene catalyst and having a heat of fusion in the range of 60 J / g or less is applied to a phosphorus-free non-halogen flame retardant resin composition. A base polymer (A) as a main component is used. Since the ethylene-α olefin copolymer (a1) is polymerized by a metallocene catalyst, it has excellent mechanical strength and flexibility. In addition, the volume resistivity is small and the insulation is excellent. Furthermore, since the heat of fusion is in the range of 60 J / g or less, even when a large amount of flame retardant is added, it is possible to suppress a decrease in heat resistance due to a large amount of flame retardant and maintain high heat resistance. it can. Therefore, by using the base polymer (A) whose main component is the ethylene-α-olefin copolymer (a1), the mechanical strength having a tensile strength of 7 MPa or more and the elongation of 350% or more, and 100% modulus are obtained. Flexibility of 6 MPa or less, heat resistance with a tensile strength residual ratio of 80% or more and an elongation residual ratio of 80% or more after a heat aging test at 150 ° C. for 96 hours, and a volume resistivity of 1 × 10 ¹⁴ A phosphorus-free non-halogen flame retardant resin composition having an insulating property of Ω · cm or more and excellent in various properties can be obtained.

(B) EVA (a2) containing 40% by mass or more of vinyl acetate is contained in an amount of 5 to 30 parts by mass with respect to 100 parts by mass of the base polymer (A). Since EVA (a2) has a high endothermic amount, the flame retardancy of the phosphorus-free non-halogen flame retardant resin composition can be improved.

(C) EVA (a2) has a melt flow rate of 50 g / 10 min or more. Since such EVA (a2) functions as a wax, the viscosity of the phosphorus-free non-halogen flame retardant resin composition can be lowered to improve the extrusion moldability. Thereby, the extrusion appearance of a coating layer can be made favorable.

(D) 5 parts by mass or more of maleic acid-modified ethylene copolymer (a3) is contained with respect to 100 parts by mass of the base polymer (A). The maleic acid-modified ethylene copolymer (a3) is phosphorus-free by improving the adhesion at the interface between the ethylene-α olefin copolymer (a1) or EVA (a2) and the non-halogen flame retardant (B). While improving the mechanical strength of a halogen-free flame retardant resin composition, the heat resistance fall by a halogen-free flame retardant (B) can further be suppressed.

(E) The non-halogen flame retardant (B) is contained in an amount of 100 parts by mass to 250 parts by mass with respect to 100 parts by mass of the base polymer (A). Thereby, high flame retardance can be acquired, suppressing the mechanical strength by a flame retardant, a softness | flexibility, insulation, and the fall of heat resistance.

(F) As the non-halogen flame retardant (B), a fatty acid-treated metal hydroxide is contained. Thereby, flexibility can be obtained while maintaining the mechanical strength.

(G) By using the phosphorus-free non-halogen flame retardant resin composition according to this embodiment, an electric wire or cable excellent in mechanical strength, flexibility, insulation, and heat resistance can be obtained.

  Next, the present invention will be described more specifically with reference to examples. The present invention is not limited to the following examples.

(1) Preparation of non-halogen flame retardant resin composition The non-halogen flame retardants of Examples 1 to 5 and Comparative Examples 1 to 8 were prepared by blending various components as shown in Table 1 below and kneading them using a roll machine. A functional resin composition was prepared. In Table 1, the numerical values for the composition are shown in parts by mass.

(2) Production of electric wire Next, using a 40 mm extruder (L / D = 22) maintained at 100 ° C., the above-described non-halogen flame retardant resin composition was tin-plated copper stranded wire conductor having a conductor diameter of 2.3 mm. Extrusion-coating with a thickness of 1.1 mm on the outer periphery of the film to form an insulating layer, followed by crosslinking the insulating layer with 13 kg / cm ² of steam for 3 minutes, thereby allowing Examples 1 to 5 and Comparative Examples 1 to 8 The electric wire was produced.

(3) Evaluation method Mechanical strength, flexibility, heat resistance, volume resistivity, extrusion appearance, and flame retardancy were measured for the insulation layers of the produced electric wires. Hereinafter, each measurement method will be specifically described.

(Mechanical strength)
Mechanical strength was evaluated by the tensile strength and elongation of the insulating layer. Specifically, a tensile test was performed in accordance with JIS C3005 on the insulating layer formed into a tube shape by extracting the conductor from the electric wire, and the tensile strength and elongation of the insulating layer were measured. In this example, the tensile strength was set to 7 MPa or more and the elongation was set to 350% or more. When the tensile strength is less than 7 MPa or the elongation is less than 350, the mechanical strength of the insulating layer becomes insufficient.

(Flexibility)
Flexibility was evaluated by the 100% modulus of the insulating layer. Specifically, a test was performed in accordance with JIS C3005 on an insulating layer formed into a tube shape by drawing a conductor from an electric wire, and a 100% modulus was measured. In this example, the target for 100% modulus was 6 MPa or less. When the 100% modulus exceeds 6 MPa, the insulating layer is hard and the flexibility becomes insufficient.

(Heat-resistant)
The heat resistance was evaluated by the degree of deterioration when the insulating layer was deteriorated (aged) by heating. Specifically, first, by conducting a heat aging test in accordance with JIS C3005, a conductor is drawn out of an electric wire and a tube-shaped insulating layer is put in a heat aging test machine at 150 ° C. for 96 hours, and then taken out. Mechanical strength (tensile strength and elongation) after heat aging was measured. Then, as shown in the following formula, the residual ratios of the mechanical strength after deterioration (the residual ratio of tensile strength (%) and the residual ratio of elongation (%)) with respect to the mechanical strength before deterioration (initial) were calculated. In this example, both the tensile strength residual rate (%) and the elongation residual rate (%) were targeted to be 80% or more. When these residual ratios are less than 80%, the insulating layer is excessively deteriorated by heating, resulting in insufficient heat resistance.
Tensile strength residual rate (%) = (Tensile strength after test / Tensile strength before test) × 100
Residual elongation (%) = (Elongation after test / Elongation before test) × 100 (%)

(Insulation)
The insulation was evaluated by the volume resistivity of the insulating layer. Specifically, in accordance with JIS K6271, a volume resistance of a sheet having a thickness of 1 mm produced by press-crosslinking a non-halogen flame retardant resin composition into a sheet is 500 V for 1 minute. The rate was measured. In this example, the volume resistivity was set to 1 × 10 ¹⁴ Ω · cm or more. When the volume resistivity is less than 1 × 10 ¹⁴ Ω · cm, the insulation is insufficient.

(Extruded appearance)
The extrusion appearance was evaluated by visually observing the surface of the insulating layer to determine whether it was smooth.

(Flame retardance)
The flame retardancy was evaluated by a vertical tray combustion test (VTFT) in accordance with the BS 6853 standard, BS EN60332 Part 3-21 test method. Specifically, a wire with a total length of 3.5 m is made into one bundle of 7 twists, 11 bundles are arranged vertically at equal intervals, burned for 20 minutes, and after self-extinguishing, the carbonization length is 2.5 m from the lower end. The following were targeted. If the carbonization length was 2.5 m or less, the test was accepted, and if it exceeded 2.5 m, the test was rejected.

(4) Evaluation results Table 1 shows the evaluation results. In Table 1, a sample in which the mechanical strength, flexibility, heat resistance, volume resistivity and flame retardancy evaluation satisfied the above-described targets was set as an example, and a sample that did not satisfy the target was set as a comparative example.

  As shown in Table 1, in Examples 1-5, mechanical strength, flexibility, heat resistance, insulation, and flame retardance were all good. Thus, it was found that a phosphorus-free non-halogen flame retardant resin composition having excellent mechanical strength, flexibility, heat resistance, and insulating properties can be obtained.

  Comparative Example 1 was confirmed to have lower heat resistance than Examples 1 and 2. As the ethylene-α-olefin copolymer, one having a heat of fusion of 27 J / g was used in Example 1, and one having a heat of fusion of 37 J / g was used in Example 2, whereas it was melted in Comparative Example 1. A heat quantity of 79 J / g was used. From this, it was found that high heat resistance can be obtained by using an ethylene-α-olefin copolymer having a low heat of fusion of 60 J / g or less. In addition, referring to Examples 1 and 2 and Comparative Example 1, as the heat of fusion of the ethylene-α-olefin copolymer becomes as small as 79 J / g, 37 J / g, and 27 J / g, the tensile strength residual ratio and the elongation residual ratio are reduced. It has been found that the rate tends to increase and the heat resistance tends to increase.

  Comparative Example 2 was confirmed to have lower mechanical strength and heat resistance than Examples 1-5. In Examples 1 to 5, the EVA content with an MFR of 100 g / 10 min was 10 to 30 parts by mass, whereas in Comparative Example 2, the content was 35 parts by mass. From this, it was found that the mechanical strength is lowered by increasing the amount of EVA. Moreover, in the comparative example 2, since the ratio of the ethylene-alpha olefin copolymer became small by the increase in EVA, it turned out that sufficient heat resistance cannot be acquired.

  Comparative Example 3 was confirmed to have lower mechanical strength and heat resistance than Examples 1-5. In Examples 1 to 5, the content of maleic acid-modified ethylene copolymer in 100 parts by mass of the base polymer was 5 parts by mass or more, whereas in Comparative Example 3, the content was 2 parts by mass. Therefore, when the content of the maleic acid-modified ethylene copolymer is less than 5 parts by mass, the adhesiveness between the metal hydroxide and the base polymer is low, so that not only the mechanical strength but also the heat resistance is lowered. I understood that.

  Comparative Example 4 was confirmed to have lower mechanical strength, flexibility, heat resistance, and insulation than Examples 1 and 5. In Example 1, the content of the non-halogen flame retardant was 150 parts by mass with respect to 100 parts by mass of the base polymer, and in Example 5, it was 200 parts by mass, whereas in Comparative Example 4, it was 270 parts by mass. From this fact, it was found that when the halogen-free flame retardant is contained in an amount of more than 250 parts by mass, even if an ethylene-α olefin copolymer having a small amount of heat of fusion is used, the deterioration of various characteristics is large and high characteristics cannot be maintained. . In addition, as shown in Examples 1 and 5, it was found that as the content of the non-halogen flame retardant increases, various characteristics tend to decrease.

  It was confirmed that Comparative Example 5 has lower flame retardancy than Example 1. In Example 1, the content of the non-halogen flame retardant was 150 parts by mass with respect to 100 parts by mass of the base polymer, whereas in Comparative Example 5, the content was 80 parts by mass. From this, it was found that if the halogen-free flame retardant is contained in less than 100 parts by mass, sufficient flame retardancy cannot be obtained.

  Comparative Example 6 was confirmed to be less flexible than Example 1. In Example 1, magnesium hydroxide treated with fatty acid was used as the non-halogen flame retardant, whereas magnesium hydroxide treated with silane was used in Comparative Example 6. From this, using silane-treated metal hydroxide provides high adhesion to the base polymer and high tensile strength (mechanical strength) is obtained, but the adhesion is too high. It turns out that the nature becomes low. On the other hand, when magnesium hydroxide treated with fatty acid was used, it was found that appropriate adhesion to the base polymer was obtained, and both mechanical strength and flexibility could be achieved.

  Since the comparative example 7 was not able to extrude a phosphorus-free non-halogen flame retardant resin composition satisfactorily, each evaluation as in Examples 1 to 5 could not be performed. In Examples 1 to 5, EVA having an MFR of 100 g / 10 min was used, whereas in Comparative Example 7, EVA having an MFR of 2.5 g / 10 min was used. From this, in Examples 1 to 5, it is considered that EVA having a relatively large MFR functions as a wax, whereby the viscosity of the phosphorus-free non-halogen flame retardant resin composition can be lowered and extruded well. .

  Since the comparative example 8 was not able to extrude a phosphorus-free non-halogen flame retardant resin composition satisfactorily, each evaluation as in Examples 1 to 5 could not be performed. In Examples 1 to 5, the content of EVA having an MFR of 100 g / 10 min was 5 to 30 parts by mass with respect to 100 parts by mass of the base polymer, whereas in Comparative Example 8, the content was 2 parts by mass. Therefore, in Examples 1 to 5, it is considered that the viscosity of the phosphorus-free non-halogen flame retardant resin composition can be lowered and extruded well by containing 5 parts by mass or more of EVA functioning as a wax. It is done.

<Preferred embodiment of the present invention>
Hereinafter, preferred embodiments of the present invention will be additionally described.

[Appendix 1]
According to one aspect of the invention,
The main component is an ethylene-α olefin copolymer (a1) in which ethylene and an α-olefin having 3 to 8 carbon atoms are polymerized by a metallocene catalyst, and the heat of fusion measured by a differential scanning calorimeter is in the range of 60 J / g or less. Containing a base polymer (A)
Mechanical strength having a tensile strength of 7 MPa or more and an elongation of 350% or more;
Flexibility with 100% modulus of 6 MPa or less;
Heat resistance with a tensile strength residual rate of 80% or more and an elongation residual rate of 80% or more after a heat aging test at 150 ° C. for 96 hours,
A phosphorus-free non-halogen flame retardant resin composition having an insulating property with a volume resistivity of 1 × 10 ¹⁴ Ω · cm or more is provided.

[Appendix 2]
In the phosphorus-free non-halogen flame retardant resin composition of Appendix 1, preferably,
The base polymer (A) is 5 parts by mass or more and 30 parts by mass or less of an ethylene-vinyl acetate copolymer (a2) containing 40% by mass or more of vinyl acetate with respect to 100 parts by mass of the base polymer (A). Containing 5 parts by mass or more of maleic acid-modified ethylene copolymer (a3) obtained by modifying a copolymer of ethylene and an α-olefin having 3 to 8 carbon atoms with maleic anhydride,
The halogen-free flame retardant (B) is contained in an amount of 100 parts by mass or more and 250 parts by mass or less with respect to 100 parts by mass of the base polymer (A).

[Appendix 3]
In the phosphorus-free non-halogen flame retardant resin composition of Appendix 2, preferably,
The ethylene-vinyl acetate copolymer (a2) has a melt flow rate of 50 g / 10 min or more.

[Appendix 4]
In the phosphorus-free non-halogen flame retardant resin composition according to appendix 2 or 3,
The non-halogen flame retardant (B) contains a fatty acid-treated metal hydroxide.

[Appendix 5]
Conductors,
A coating layer covering the outer periphery of the conductor,
The said coating layer is provided with the electric wire currently formed with the phosphorus-free non-halogen flame-retardant resin composition of Additional remarks 1-4.

[Appendix 6]
Electric wires,
A coating layer covering the outer periphery of the electric wire,
A cable is provided in which the coating layer is formed of the phosphorus-free non-halogen flame-retardant resin composition according to appendices 1 to 4.

DESCRIPTION OF SYMBOLS 1 Conductor 2 Insulation layer 3 Interposition 4 Sheath 10 Electric wire 11 Cable

Claims (6)

The main component is an ethylene-α olefin copolymer (a1) in which ethylene and an α-olefin having 3 to 8 carbon atoms are polymerized by a metallocene catalyst, and the heat of fusion measured by a differential scanning calorimeter is in the range of 60 J / g or less. Containing a base polymer (A)
Mechanical strength having a tensile strength of 7 MPa or more and an elongation of 350% or more;
Flexibility with 100% modulus of 6 MPa or less;
Heat resistance with a tensile strength residual rate of 80% or more and an elongation residual rate of 80% or more after a heat aging test at 150 ° C. for 96 hours,
A phosphorus-free non-halogen flame retardant resin composition having an insulating property with a volume resistivity of 1 × 10 ¹⁴ Ω · cm or more. The base polymer (A) is 5 parts by mass or more and 30 parts by mass or less of an ethylene-vinyl acetate copolymer (a2) containing 40% by mass or more of vinyl acetate with respect to 100 parts by mass of the base polymer (A). Containing 5 parts by mass or more of maleic acid-modified ethylene copolymer (a3) obtained by modifying a copolymer of ethylene and an α-olefin having 3 to 8 carbon atoms with maleic anhydride,
The phosphorus-free non-halogen flame retardant resin composition according to claim 1, wherein the halogen-free flame retardant (B) is contained in an amount of 100 parts by mass to 250 parts by mass with respect to 100 parts by mass of the base polymer (A).   The phosphorus-free non-halogen flame retardant resin composition according to claim 2, wherein the ethylene-vinyl acetate copolymer (a2) has a melt flow rate of 50 g / 10 min or more.   The phosphorus-free non-halogen flame retardant resin composition according to claim 2 or 3, comprising a fatty acid-treated metal hydroxide as the non-halogen flame retardant (B). Conductors,
A coating layer covering the outer periphery of the conductor,
The said coating layer is an electric wire currently formed with the phosphorus-free non-halogen flame-retardant resin composition in any one of Claims 1-4. Electric wires,
A coating layer covering the outer periphery of the electric wire,
The said coating layer is a cable formed of the phosphorus-free non-halogen flame retardant resin composition according to any one of claims 1 to 4.

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