JP2022119412A - Resin composition, electric wire and cable - Google Patents

Abstract

To provide a resin composition excellent in fire retardancy and suppressed in a tension strength change in heat aging, and to provide an electric wire and a cable formed by using the resin composition.SOLUTION: A resin composition contains: (A) an ethylene-based polymer; (B) a metal hydroxide; and (C) at least one compound in a compound in which at least one hydroxy group among three hydroxy groups that a gallic acid has is substituted with an alkoxy group, a phenoxy group or a silyl ether group, and a compound in which at least one hydroxy group of three hydroxy groups that a gallic acid ester has is substituted with an alkoxy group, a phenoxy group or a silyl ether group.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to resin compositions, electric wires, and cables.

An electric wire includes a conductor and a coating layer provided around the conductor. Also, the cable includes, for example, a stranded wire obtained by twisting such electric wires and a sheath provided around the stranded wire. The coating layer of the electric wire and the sheath of the cable are generally made of an electrically insulating material mainly composed of rubber, resin, or the like.

Various properties are required for the coating layer of the electric wire and the sheath of the cable according to the application. For example, electric wires and cables for electronic devices and railway vehicles shall be made of halogen-free materials that suppress the generation of toxic and corrosive gases when combusted, and shall have high flame resistance. etc. is required.

As a material that satisfies such requirements, Patent Document 1 describes a resin composition obtained by adding a metal hydroxide such as magnesium hydroxide as a flame retardant to a resin component having an ethylene polymer as a base polymer. .

Japanese Unexamined Patent Application Publication No. 2015-2062

However, according to the studies of the present inventors, when higher flame retardancy is required, the resin composition described in Patent Document 1 may not be sufficient.
On the other hand, the present inventors have found that by adding a compound having a plurality of phenolic hydroxyl groups in the molecule, such as gallic acid ester, flame retardancy is significantly improved due to the high radical trapping effect of the phenolic hydroxyl group. found to improve. The radical trapping effect refers to the effect of capturing the generated radicals with phenolic hydroxyl groups. As a result, the flame retardant captures radicals generated from the combusted material during combustion, thereby suppressing the reaction between the resin composition and oxygen.

However, as a result of further studies by the present inventors, when a resin composition containing a compound having a plurality of phenolic hydroxyl groups in the molecule is heat-aged, the tensile strength increases, and the tensile strength from the initial state increases. It was newly found that the rate of change in strength becomes large.

One aspect of the present disclosure provides a resin composition that is excellent in flame retardancy and suppresses change in tensile strength during heat aging, and an electric wire and a cable that are formed using the resin composition.

One aspect of the present disclosure is a resin composition, wherein at least one of the three hydroxyl groups of (A) an ethylene-based polymer, (B) a metal hydroxide, and (C) gallic acid is an alkoxy a compound substituted with a group, a phenoxy group, or a silyl ether group, and a compound in which at least one of the three hydroxyl groups of the gallic acid ester is substituted with an alkoxy group, a phenoxy group, or a silyl ether group, and at least one compound of

According to one aspect of the present disclosure, a resin composition having excellent flame retardancy and suppressed change in tensile strength during heat aging, and an electric wire and cable formed using the resin composition are provided. .

It is a cross-sectional view showing the structure of the electric wire according to the first embodiment. It is a cross-sectional view which shows the structure of the electric wire which concerns on 2nd Embodiment. It is a cross-sectional view which shows the structure of an example of a cable.

In the resin composition of one embodiment of the present disclosure, at least one of the three hydroxyl groups of (A) an ethylene-based polymer, (B) a metal hydroxide, and (C) gallic acid has an alkoxy group, a phenoxy or a silyl ether group, and at least a compound in which at least one of the three hydroxyl groups of the gallic acid ester is substituted with an alkoxy group, a phenoxy group, or a silyl ether group. and a compound.

As described below, such a resin composition is excellent in flame retardancy and suppresses changes in tensile strength during heat aging. In addition, change in elongation during heat aging is suppressed.
As described above, according to the studies of the present inventors, compounds having a plurality of phenolic hydroxyl groups in the molecule, such as gallic acid esters, can improve the flame retardancy of the resin composition. However, when a resin composition containing such a compound is heat-aged, the tensile strength from the initial state increases and at the same time the elongation decreases, resulting in a large rate of change. Such a situation is not desirable because it runs counter to the design concept that a smaller change in physical properties is better under heating conditions for a relatively short period of time.

The reason why such a phenomenon occurs is that the phenolic hydroxyl group captures radicals that may be generated during the manufacture of the wire coating layer and the cable sheath, and releases the captured radicals during heat aging, resulting in a cross-linking reaction of the base polymer. This is thought to be because For example, a resin composition may be crosslinked in order to increase the heat resistance of a coating layer of an electric wire and a sheath of a cable, and radicals may be generated during this crosslinking.

In order to achieve both radical scavenging during combustion and suppression of radical donation during heat aging, the present inventors have found that by protecting the phenolic hydroxyl group, the reactivity of the phenolic hydroxyl group is temporarily reduced while burning. I thought it would be effective to return to the original hydroxyl group at times. In other words, by replacing only the hydrogen with another structure while leaving the oxygen of the phenolic hydroxyl group, the reactivity of the phenolic hydroxyl group is suppressed, so it is thought that changes in tensile strength, etc. during heat aging are suppressed. be done. In addition to this, if the replaced portion desorbs in a high-temperature environment during combustion and returns to the original hydroxyl group to restore the radical trapping effect, it is thought that high flame retardancy can be maintained. Therefore, the present inventors have made various studies on how to protect the hydroxyl groups of compounds such as gallic acid esters.

As a result, by substituting at least one of the three hydroxyl groups of gallic acid or gallic acid ester with an alkoxy group, a phenoxy group, or a silyl ether group, while maintaining high flame retardancy, It was found that changes in tensile strength and the like during aging can be suppressed.

Hereinafter, a resin composition, an electric wire, and a cable according to one aspect of the present disclosure will be described in detail.
<Resin composition>
The resin composition is a halogen-free flame-retardant resin composition.
Each component contained in the resin composition will be described in detail below. In addition, below, (B) component and (C) component may be collectively demonstrated as a flame retardant.
[(A) Component]
Examples of the ethylene-based polymer (A) include ethylene-vinyl acetate copolymers, ethylene-acrylate copolymers, ethylene-α-olefin copolymers, and the like. Component (A) preferably contains an ethylene-vinyl acetate copolymer. Also, the component (A) is preferably the base polymer in the resin composition.

[(B) Component]
(B) Component metal hydroxides include, for example, magnesium hydroxide, aluminum hydroxide, hydrotalcite, boehmite, calcium hydroxide, iron (II) hydroxide, and iron (III) hydroxide. Component (B) preferably contains magnesium hydroxide.

Examples of magnesium hydroxide include those with no surface treatment and those with surface treatment. Examples of surface-untreated magnesium hydroxide include natural magnesium hydroxide obtained by pulverizing brucite ore, synthetic magnesium hydroxide, and the like. Those surface-treated include those surface-treated with a silane coupling agent, phosphate ester, fatty acid (eg, stearic acid, oleic acid, etc.), or fatty acid salt.

Magnesium hydroxide is preferably surface-treated with a silane coupling agent. This is because magnesium hydroxide surface-treated with a silane coupling agent has a high affinity with the component (A), so that the tensile properties of the resin composition are improved.

The content of component (B) in the resin composition is preferably 50 parts by mass or more and 300 parts by mass or less, and 100 parts by mass or more and 250 parts by mass or less per 100 parts by mass of component (A). is more preferred. When the content of the component (B) is 50 parts by mass or more per 100 parts by mass of the component (A), the resulting electric wire, cable, etc. will have higher flame retardancy. Further, when the content of component (B) is 300 parts by mass or less per 100 parts by mass of component (A), the adhesion and aggregation of the metal hydroxide particles are suppressed, resulting in the formation of a resin composition. Since the fluidity is less likely to decrease, the processability of the resin composition, for example, the processability by extrusion molding, etc., is good.

[(C) Component]
The compound of component (C) is a compound in which at least one of the three hydroxyl groups of gallic acid is substituted with an alkoxy group, a phenoxy group, or a silyl ether group, and the three hydroxyl groups of a gallic acid ester. at least one of the compounds in which at least one hydroxyl group is substituted with an alkoxy group, a phenoxy group, or a silyl ether group. Gallic acid is a compound represented by the following formula (1).

The carboxylic acid group in gallic acid may be esterified as it is in the carboxylic acid structure as long as the hydroxyl group side is protected. As the ester, an alkyl ester having a small number of carbon atoms, such as a lower alkyl ester having 1 to 4 carbon atoms, is preferable. As the gallic acid ester, at least one selected from methyl gallate represented by the following formula (2) and propyl gallate represented by the following formula (3) is particularly preferable.

In the compound of component (C), at least one of the three hydroxyl groups may be substituted. Moreover, the position of the substituent may be any of 3, 4 and 5 positions. From the viewpoint of further suppressing radical donation during heat aging, it is preferable that a plurality of (that is, two or three) hydroxyl groups are substituted, and it is more preferable that all hydroxyl groups are substituted. The reason why the effect of suppressing radical donation during heat aging is exhibited is unknown even if not all hydroxyl groups are necessarily protected, but the present inventors believe that the radical scavenging ability is reduced due to steric hindrance. they are thinking.

As the alkoxy group for the substituent, an alkoxy group having 1 to 4 carbon atoms such as a methoxy group, an ethoxy group, and a butoxy group is preferable, and a methoxy group is more preferable from the viewpoint of availability.
Examples of compounds substituted with alkoxy groups include 3,4,5-trimethoxybenzoic acid (also known as eudesmic acid) and its alkyl esters, 3,5-dimethoxy-4-hydroxybenzoic acid (also known as syringic acid) and Alkyl ester thereof and the like can be mentioned. Examples of alkyl esters of eudesmic acid include alkyl esters having 1 to 4 carbon atoms such as methyl eudesmate and propyl eudesmate. Examples of alkyl esters of syringic acid include alkyl esters having 1 to 4 carbon atoms such as methyl syringate.

As the compound substituted with an alkoxy group, eudesmic acid and its alkyl ester are preferable, and eudesmic acid is more preferable, from the viewpoint of further suppressing radical donation during heat aging.
Examples of compounds substituted with a phenoxy group include 3,4,5-triphenoxybenzoic acid and its alkyl esters, 4-phenoxy-3,5-dihydroxybenzoic acid and its alkyl esters, 3-phenoxy-4,5 -dihydroxybenzoic acid and its alkyl esters, 3,4-diphenoxy-5-dihydroxybenzoic acid and its alkyl esters, and the like. In these cases, the alkyl ester is preferably an alkyl ester having 1 to 4 carbon atoms.

Examples of the silyl ether group as the substituent include trialkylsilyloxy groups having 1 to 4 carbon atoms such as trimethylsilyloxy, triethylsilyloxy and tri-t-butylsilyloxy. As the silyl ether group, a trimethylsilyloxy group is more preferable because it is easily deprotected during combustion.

A silyl ether group can be introduced into a compound by silyl-etherifying a hydroxyl group using a silane compound. Silane compounds used for silyl etherification include chlorosilane compounds such as trimethylchlorosilane, triethylchlorosilane, and tri-t-butylchlorosilane. Protection with a silyl ether group can be easily achieved, for example, by dropping a chlorosilane compound into a solution in which gallic acid or a gallic acid ester is dissolved together with a base for reaction.

When an ethylene-vinyl acetate copolymer is used as the ethylene-based polymer (A), the substituent is preferably a silyl ether group. In an acidic environment due to the elimination of acetic acid during combustion, the silyl ether group is quickly deprotected and the compound quickly returns to the original gallic acid or gallic acid ester, so flame retardancy is easily maintained. It is from.

Examples of compounds substituted with silyl ether groups include 3,4,5-tris(trimethylsilyloxy)benzoic acid and its alkyl esters, 3,5-di(trimethylsilyloxy)-4-hydroxybenzoic acid and its alkyl esters. , 3-trimethylsilyloxy-4,5-dihydroxybenzoic acid and its alkyl esters, 3,4,5-tris(tri-t-butylsilyloxy)benzoic acid and its alkyl esters, and the like. Examples of alkyl esters of 3,4,5-tris(trimethylsilyloxy)benzoic acid include alkyl esters having 1 to 4 carbon atoms such as 3,4,5-tris(trimethylsilyloxy)propyl benzoate. Examples of alkyl esters of 3,5-di(trimethylsilyloxy)-4-hydroxybenzoic acid include alkyl esters having 1 to 4 carbon atoms such as propyl 3,5-di(trimethylsilyloxy)-4-hydroxybenzoate. mentioned. Examples of alkyl esters of 3-trimethylsilyloxy-4,5-dihydroxybenzoic acid include alkyl esters having 1 to 4 carbon atoms such as propyl 3-(trimethylsilyloxy)-4,5-dihydroxybenzoate. Examples of alkyl esters of 3,4,5-tris(tri-t-butylsilyloxy)benzoic acid include those having 1 to 4 carbon atoms such as 3,4,5-tris(tri-t-butylsilyloxy)propyl benzoate. Alkyl ester etc. are mentioned.

Among the alkoxy group, phenoxy group and silyl ether group, the substituent is preferably an alkoxy group or a silyl ether group, more preferably an alkoxy group, from the viewpoint of further suppressing radical donation during heat aging.

The content of component (C) is preferably 1 part by mass or more and 50 parts by mass or less, more preferably 2 parts by mass or more and 30 parts by mass or less per 100 parts by mass of component (A). When the content of the component (C) is 1 part by mass or more per 100 parts by mass of the component (A), the resulting electric wire, cable, etc. will have high flame retardancy. Further, when the content of component (C) is 50 parts by mass or less per 100 parts by mass of component (A), the tensile strength of the resin composition is improved.

[Other ingredients]
In addition to the above components, the resin composition may optionally contain other components within the range that does not affect the above properties. Other components include, for example, flame retardants other than the above, flame retardant aids, cross-linking agents, cross-linking aids, processing aids, coupling agents, surface treatment agents, colorants, lubricants, compatibilizers, antioxidants. , antiozonants, ultraviolet absorbers, light stabilizers, metal chelators, softeners, plasticizers and the like.

<Electric wire>
[First embodiment]
A wire 10 shown in FIG. 1 is a halogen-free flame-retardant insulated wire according to the first embodiment. The electric wire 10 includes a conductor 1 , an insulating layer 2 as a covering layer covering the conductor 1 , and a separator 3 provided between the conductor 1 and the insulating layer 2 .

As the conductor 1, a commonly used metal wire such as a copper wire, a copper alloy wire, an aluminum wire, a gold wire, a silver wire, or the like can be used. As the conductor 1, a metal wire plated with a metal such as tin or nickel may be used. As the conductor 1, a twisted wire obtained by twisting metal wires may be used. As the twisted wire, a concentric twisted wire, a bundled twisted wire, a composite twisted wire obtained by further concentrically twisting these wires, and the like can be used. As the conductor 1, a compressed conductor obtained by compressing a stranded wire may be used. Compressed conductors are preferred because they allow the diameter of the wire to be reduced.

The insulating layer 2 is made of the above resin composition. Although the thickness of the insulating layer 2 is not particularly limited, it is preferably 0.15 mm or more and 2 mm or less.
The separator 3 is made of polyester tape or the like, for example. By providing the separator 3, when a twisted conductor is used as the conductor 1, it is possible to suppress the penetration of the resin composition into the inside of the conductor 1 when the resin composition is extruded, that is, when the insulating layer 2 is formed. can be done. Note that the electric wire 10 may not have the separator 3 .

The electric wire 10 can be manufactured, for example, as follows.
First, materials containing the above components (A) to (C) and other components are melt-kneaded to obtain a resin composition. As the kneading device, known kneading devices such as a Banbury mixer, a batch kneader such as a pressure kneader, and a continuous kneader such as a twin-screw extruder can be used.

Then, the conductor 1 is prepared and the separator 3 is wound around the conductor 1 . Thereafter, the circumference of the separator 3 is covered with a resin composition by an extruder. Thereby, the insulating layer 2 having a predetermined thickness can be formed.

Then, the insulating layer 2 is cross-linked by, for example, an electron beam cross-linking method, a chemical cross-linking method, or the like. Although the cross-linking treatment is not essential, it is preferable to cross-link the insulating layer 2 because the heat resistance of the insulating layer 2 is improved by performing the cross-linking treatment on the insulating layer 2 . When the electron beam crosslinking method is used, the insulating layer 2 is irradiated with an electron beam of, for example, 1 Mrad or more and 30 Mrad or less (0.01 MGy or more and 0.3 MGy or less). When using the chemical cross-linking method, for example, a cross-linking agent is added in advance to the resin composition, and after the resin composition is molded as the insulating layer 2 of the electric wire 10, the insulating layer 2 is heat-treated. In addition, the electron beam cross-linking method is used in the examples described later.

[Second embodiment]
The wire 20 shown in FIG. 2 is a halogen-free flame-retardant insulated wire according to the second embodiment. The electric wire 20 differs from the electric wire 10 according to the first embodiment in that the insulating layer 2 is composed of two layers and that the separator 3 is not provided. Specifically, the electric wire 20 includes a conductor 1, an insulating inner layer 2a provided around the conductor 1, and an insulating outer layer 2b provided around the insulating inner layer 2a. The insulating inner layer 2a is made of insulating resin such as polyethylene. The insulating outer layer 2b is made of the above resin composition. Note that the insulating outer layer 2b corresponds to a coating layer.
Note that the electric wire 20 may be provided with the separator 3 in the same manner as the electric wire 10 . Moreover, the insulating layer 2 may have three or more layers.

<Cable>
The cable 30 shown in FIG. 3 is a halogen-free, flame-retardant cable. The cable 30 includes a core 4 , a sheath 5 as a coating layer covering the core 4 , a separator 6 and a shield braid 7 provided between the core 4 and the sheath 5 .

The core 4 has a three-core stranded wire 4a obtained by twisting three wires 10 and an interposition 4b provided around the three-core stranded wire 4a. Interposition 4b is made of staple thread, paper tape, jute, or the like. Note that the core 4 does not have to have the interposition 4b.

The sheath 5 is made of the above resin composition. The separator 6 is the same as the separator 3 in the electric wire 10 described above. A shield braid 7 is provided around the separator 6 and has an electrical shielding function. The shield braid 7 is formed of, for example, a metal tape, copper wire, or the like woven into a mesh. The shield braid 7 may be provided inside the separator 6 and the cable 30 may not have the shield braid 7 .

Cable 30 can be manufactured, for example, as follows.
First, three electric wires 10 are manufactured by the same method as described above. After that, the three wires 10 are twisted together with the intermediate 4b to form the core 4, and the separator 6 and the shielding braid 7 are provided around the core 4. As shown in FIG. After that, they are covered with a resin composition using an extruder. Thereby, the sheath 5 with a predetermined thickness can be formed.

Then, if necessary, the sheath 5 is crosslinked by the same method as described above. Thereby, the cable 30 can be manufactured.
It should be noted that another electric wire may be used instead of the electric wire 10 . Also, instead of the three-core stranded wire 4a, a single core composed of one electric wire may be used, or a multi-core stranded wire other than the three-core stranded wire may be used. Also, between the core 4 and the sheath 5, other layers, such as other insulating layers, may be provided.

<Other uses of the resin composition>
The above resin compositions can be used in wires and cables of various uses and sizes. For example, electric wires and cables are used for electronic equipment, railway vehicles, automobiles, wiring in boards, wiring in equipment, wiring in buildings, and the like. Since wires and cables for electronic devices or railway vehicles require particularly high flame retardancy, the resin composition can be suitably used for wires and cables for electronic devices or railway vehicles. Also, the type of cable is not particularly limited, and may be, for example, a power cable, a signal cable, or the like.

Moreover, the resin composition can be used not only for the electric wires and cables but also for other applications. For example, the resin composition is used for films, panels, mats, pipes, protective materials, fillers, fibers, resin moldings, resin substrates, stationery, building materials, connectors, bushes, grommets, terminal blocks, terminal internal insulators, etc. can do.

An embodiment of the present disclosure will be described below with reference to examples, but the present disclosure is not limited to the following examples.
<Production of Resin Composition for Cable Sheath>
Each material according to Examples 1 to 8 and Comparative Examples 1 to 4 shown in Table 1 below was dry blended at room temperature, and the mixed material was melt-kneaded with a pressure kneader at a withdrawal temperature of 190 ° C. to obtain a cable. were produced respectively. In addition, the unit of content of each material in Table 1 is parts by mass.

In the resin compositions of Examples 1, 2, and 6 to 8, (C1) eudesmic acid represented by the following formula (4) was used as the (C) component. In the resin compositions according to Examples 1, 2, and 6 to 8, the content of (C1) eudesmic acid was varied.

In the resin composition according to Example 3, (C2) methyl syringate represented by the following formula (5) was used as the (C) component.

In the resin composition according to Example 4, (C3) silyl-protected propyl gallate 1 (3,4,5-tris(trimethylsilyloxy)propyl benzoate represented by the following formula (6)) was used as the component (C). was used. Silyl-protected propyl gallate 1 was synthesized as follows. Propyl gallate was dissolved in acetone, and 5 equivalents of triethylamine per 1 equivalent of hydroxyl group of propyl gallate and 5 equivalents of trimethylchlorosilane per 1 equivalent of hydroxyl group of propyl gallate were added to react them. . Silyl-protected propyl gallate 1 was then obtained by removing acetone and triethylamine. It was confirmed by FT-IR that the original hydroxyl group in the obtained silyl-protected propyl gallate 1 was protected.

In the resin composition according to Example 5, as the component (C), (C4) silyl-protected propyl gallate 2 (3,4,5-tris(tri-t-butylsilyloxy) represented by the following formula (7) propyl benzoate) was used. Silyl-protected propyl gallate 2 was synthesized in a similar manner to silyl-protected propyl gallate 1, using tri-t-butylchlorosilane instead of trimethylchlorosilane.

Unlike the resin compositions according to Examples 1 to 8, the resin composition according to Comparative Example 1 did not use the component (C). In the resin compositions according to Comparative Examples 2 to 4, propyl gallate with no hydroxyl groups protected was used instead of the component (C).

<Cable fabrication>
Compression tin plating with a cross-sectional area of 0.5 mm ² by extrusion molding using a 20 mm single screw extruder of Toyo Seiki Seisakusho's "Laboplastomill (registered trademark)", an extrusion coating device for manufacturing electric wires. An insulating layer with a coating thickness of 0.2 mm was formed around the copper strands. For forming the insulating layer, a resin composition produced by melt-kneading each material according to Comparative Example 1 shown in Table 1 in the same manner as the resin composition for the sheath was used. The cylinder temperature was 160° C., and the wire take-up speed was 4.0 m/min. After that, the insulating layer of the prepared electric wire was subjected to a cross-linking treatment by an electron beam cross-linking method under a condition of 7.5 Mrad, thereby cross-linking the resin composition constituting the insulating layer.

The three electric wires obtained were twisted together, wrapped with a polyester tape as a separator, and then shielded with braid around it.
Then, by extruding using a 60 mm single screw extruder, the resin composition for sheath according to Examples 1 to 8 and Comparative Examples 1 to 4 having a coating thickness of 0.45 mm around the shield braid. A sheath was formed. After that, the sheath was subjected to a cross-linking treatment by an electron beam cross-linking method under a condition of 7.5 Mrad to prepare a cable having an outer diameter of 4.5 mm.

<Evaluation method>
(1) Initial Tensile Test The sheath was removed from the prepared cable, and a dumbbell-shaped specimen was punched out from the removed sheath. Using a dumbbell-shaped test piece, a tensile test was performed according to JIS C3005:2000 to measure tensile strength and elongation. However, the tensile test was performed at a tensile speed of 250 mm/min.

(2) Heat aging test A dumbbell-shaped test piece prepared in the same manner as in the initial tensile test in (1) above was heated at 135°C for 168 hours in a gear oven. Thereafter, using the dumbbell-shaped test piece after heat aging, a tensile test was performed in the same manner as the initial tensile test to measure tensile strength and elongation. Regarding the tensile strength and elongation after heat aging, the rate of change from before heat aging (that is, at the time of the initial tensile test) was calculated.

(3) Cable Combustion Test A 600 mm length was taken from the prepared cable and used as a test sample. Using the test sample, a combustion test was conducted in accordance with IEC60332-1, and the distance from the upper support member to the burned portion was measured. It can be said that the longer the distance from the upper support member to the burned portion, the shorter the fire spread distance and the higher the flame retardancy. When the test sample burns down, the distance from the upper supporting member to the burnt-out portion is 0 mm.

(4) Comprehensive Judgment Regarding the tensile strength in the initial tensile test, those of 8 MPa or more were judged to pass, and those of less than 8 MPa were judged to be unacceptable. As for the elongation in the initial tensile test, a sample with an elongation of 125% or more was judged as acceptable, and a sample with less than 125% was judged as unacceptable.

Regarding the rate of change in tensile strength and elongation in the heat aging test, samples with a rate of change of ±30% or less were judged to be acceptable, and samples with a rate of change of greater than ±30% were judged to be unsatisfactory.
As for the combustion test, similarly to IEC60332-1, a case where the distance from the upper supporting member to the burnt part was 50 mm or more was judged to pass, and a case where the distance was less than 50 mm was judged to fail.

And finally, those that passed all of the tensile strength and elongation of the initial tensile test, the rate of change in tensile strength and elongation of the heat aging test, and the combustion test passed, and those that failed any of them. I failed. Table 1 shows the evaluation results. In Table 1, ◯ indicates a pass, and x indicates a failure.

<Evaluation results>
As shown in Table 1, Examples 1 to 8 passed all items of the initial tensile test, heat aging test, and combustion test.

On the other hand, Comparative Example 1, which did not contain the component (C), failed the combustion test. In addition, in Comparative Examples 2 and 3, in which propyl gallate with no hydroxyl groups protected was included instead of the component (C), the initial tensile test and combustion test passed, but the heat aging test failed. Met. Moreover, in Comparative Example 4, which contained only a relatively small amount of propyl gallate, it failed the combustion test as well as the heat aging test.

<Discussion>
As shown in Comparative Examples 1 to 4, it can be said that the flame test can be passed only when the gallic acid ester is blended into the resin composition. However, as shown in Comparative Examples 2 to 4, the gallic acid ester fails the heat aging test because the hydroxyl group is not protected.

Comparing Example 1 and Comparative Example 2, it can be said that the gallic acid ester and the component (C) have the same flame retardant effect. That is, it can be said that whether or not the hydroxyl group of the gallic acid ester is protected has almost no effect on the flame retardancy. This indicates the possibility that the substituent is detached during combustion.

Further, when comparing Examples 1, 2, 6, 7 and Example 8, the tensile strength in the initial tensile test is higher, so that the resin composition has the component (C) as the component (A). It can be said that it is preferable to include 2 parts by mass or more and 30 parts by mass or less with respect to the total amount of 100 parts by mass.

DESCRIPTION OF SYMBOLS 1... Conductor, 2... Insulating layer (covering layer), 2a... Inner insulating layer, 2b... Outer insulating layer (covering layer), 3, 6... Separator, 4... Core, 4a... Three-core stranded wire, 4b... Interposition, 5... Sheath, 7...Shield braid, 10, 20...Electric wire, 30...Cable.

Claims (8)

(A) an ethylene-based polymer;
(B) a metal hydroxide;
(C) a compound in which at least one of the three hydroxyl groups of gallic acid is substituted with an alkoxy group, a phenoxy group, or a silyl ether group, and at least one of the three hydroxyl groups of gallic acid ester at least one of compounds in which a hydroxyl group is substituted with an alkoxy group, a phenoxy group, or a silyl ether group;
A resin composition comprising: The component (C) is a compound in which at least one of the three hydroxyl groups of gallic acid is substituted with an alkoxy group or a silyl ether group, and at least one of the three hydroxyl groups of gallic acid ester. 2. The resin composition according to claim 1, comprising at least one compound in which a hydroxyl group is substituted with an alkoxy group or a silyl ether group. The component (C) is a compound in which at least one of the three hydroxyl groups of gallic acid is substituted with an alkoxy group, and at least one of the three hydroxyl groups of the gallic acid ester is an alkoxy group. The resin composition according to claim 1 or 2, comprising at least one compound among the compounds substituted with. The component (C) is a compound in which two or three of the three hydroxyl groups of gallic acid are substituted with alkoxy groups, and two or three of the three hydroxyl groups of gallic acid ester. 4. The resin composition according to any one of claims 1 to 3, comprising at least one compound among compounds in which one hydroxyl group is substituted with an alkoxy group. The resin composition according to any one of claims 1 to 4, wherein the component (C) contains at least one of 3,4,5-trimethoxybenzoic acid (eudesmic acid) and its alkyl ester. . The resin according to any one of claims 1 to 5, wherein the resin composition contains 2 parts by mass or more and 30 parts by mass or less of the component (C) with respect to 100 parts by mass of the component (A). Composition. An electric wire comprising a conductor and a covering layer covering the conductor,
An electric wire, wherein the coating layer is formed of the resin composition according to any one of claims 1 to 6. A cable comprising a sheath formed of the resin composition according to any one of claims 1 to 6.

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