JP2014065844A - Non-halogen flame-retardant resin composition and production method of the same, and insulated electric wire and cable using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-halogen flame-retardant resin composition that has high fire retardancy, and in which lowering of insulation performance is suppressed.SOLUTION: A non-halogen flame-retardant resin composition includes: a nonpolar polyolefin (A); an ethylene-vinyl acetate copolymer (B) in which silane crosslink is performed; and a metalhydroxide (C), and has a sea-island structure in which island phases including the ethylene-vinyl acetate copolymer (B) in which silane crosslink is performed are dispersed in a sea phase including the nonpolar polyolefin (A), wherein the metalhydroxides (C) are dispersed only in the sea phase.

Description

  The present invention relates to a halogen-free flame retardant resin composition, a method for producing the same, an insulated wire and a cable using the same.

  Awareness of environmental issues is increasing worldwide. Correspondingly, a non-halogen flame retardant resin composition that does not generate halogen gas during combustion is used for an insulating coating (insulating layer) such as an insulated wire.

  The non-halogen flame retardant resin composition is a resin composition in which a base polymer contains a non-halogen flame retardant such as a metal hydroxide. For this base polymer, a polyolefin resin, a thermoplastic elastomer (TPE), or the like is used. TPE is used as the base polymer for insulated wires that require flexibility.

  TPE is a polymer material that exhibits thermoplasticity like a thermoplastic resin at high temperatures and rubber elasticity like an elastomer at normal temperatures. Some TPEs blend a thermoplastic resin and an elastomer, and generally have a sea-island structure in which an elastomer is dispersed as a dispersed phase (island phase) within a continuous phase (sea phase) of the thermoplastic resin. . This TPE includes a dynamic cross-linking type TPE formed by dynamic cross-linking. Dynamic cross-linking is a method in which a crosslinkable elastomer component is mixed in a sea phase of a thermoplastic resin, and the elastomer component is cross-linked in a kneaded state to form a fine sea-island structure.

  In TPE, the thermoplastic resin component and the elastomer component can be arbitrarily combined. For example, Patent Document 1 proposes a non-halogen flame retardant resin composition containing TPE in which a polyolefin as a resin component and an ethylene vinyl acetate copolymer (hereinafter also referred to as EVA) as an elastomer component are combined. According to Patent Document 1, flame retardancy can be improved by using EVA as a polymer having a polar group.

  As a method for further improving the flame retardancy of the non-halogen flame retardant resin composition, for example, in Patent Document 2, the content of a metal hydroxide that is a non-halogen flame retardant is increased, and the resin composition is filled at a high density. A method is disclosed.

JP 2008-31354 A JP 2010-97881 A

  By the way, since insulated wires and cables are used as wiring for railway vehicles, automobiles, electrical equipment, etc., high insulation performance is required for the insulating layer depending on the environment in which they are used. For example, it is required to have high insulation performance even in an environment where moisture such as rain or seawater adheres or in a high temperature and high humidity environment.

  However, when the resin composition of Patent Document 1 is used for an insulated wire or cable, although high flame retardancy is obtained, there is a problem that the insulation performance is greatly deteriorated over time and the electrical characteristics are greatly deteriorated. In the resin composition of Patent Document 1, a metal hydroxide is mixed even in EVA dispersed as an island phase, and the metal hydroxide is melted and dissolved in an acidic EVA. Is generated. Due to this void, partial discharge occurs and the insulation performance is lowered. In particular, when water is applied, water penetration is significant, and the insulation performance tends to be further reduced. When the metal hydroxide is filled at a high density in order to improve flame retardancy, the electrical characteristics are greatly reduced. On the other hand, although it is conceivable to reduce the content of the metal hydroxide that causes voids, it is difficult to obtain a predetermined high flame retardancy.

  The present invention has been made in view of such problems, and an object thereof is to provide a non-halogen flame retardant resin composition having high flame retardancy and suppressed deterioration of insulation performance, and a method for producing the same. It is in. Moreover, it is providing the insulated wire and cable which have high flame retardance and favorable electrical characteristics.

According to a first aspect of the invention,
In the sea phase containing the nonpolar polyolefin (A), the silane-crosslinked ethylene vinyl acetate copolymer (B), and the metal hydroxide (C), and containing the nonpolar polyolefin (A), It has a sea-island structure in which an island phase containing the silane-crosslinked ethylene-vinyl acetate copolymer (B) is dispersed, and the metal hydroxide (C) is dispersed only in the sea phase. A non-halogen flame retardant resin composition is provided.

According to a second aspect of the invention,
The non-halogen flame retardant resin composition according to the first aspect, wherein the ethylene vinyl acetate copolymer (B) crosslinked with silane is crosslinked with an ethylene vinyl acetate copolymer having a vinyl acetate content of 20% by mass or more. Is provided.

According to a third aspect of the invention,
The nonpolar polyolefin (A) and the silane-crosslinked ethylene vinyl acetate copolymer (B) are contained in a mass ratio (A: B) in a ratio within a range of 70:30 to 30:70, The halogen-free flame retardant according to the first aspect or the second aspect, containing 50 parts by weight or more and 300 parts by weight or less of the metal hydroxide (C) with respect to 100 parts by weight in total of A) and (B). A resin composition is provided.

According to a fourth aspect of the invention,
A method for producing a non-halogen flame retardant resin composition comprising a nonpolar polyolefin (A), a silane-crosslinked ethylene-vinyl acetate copolymer (B), and a metal hydroxide (C), While kneading the polar polyolefin (A) and the ethylene vinyl acetate copolymer, the ethylene vinyl acetate copolymer was silane-crosslinked, so that the silane was crosslinked in the sea phase containing the nonpolar polyolefin (A). A step of dispersing an island phase containing an ethylene vinyl acetate copolymer (B), and a step of adding and dispersing the metal hydroxide (C) in the sea phase.
A method for producing a non-halogen flame retardant resin composition is provided.

According to a fifth aspect of the present invention,
An insulated wire is provided that includes an insulating layer made of the non-halogen flame retardant resin composition of any one of the first to third aspects on the outer periphery of a conductor.

According to a sixth aspect of the present invention,
A sheath composed of the non-halogen flame retardant resin composition of any one of the first to third aspects is provided on an insulated wire having an insulating layer on the outer periphery of a conductor or a core formed by twisting a plurality of the insulated wires, A cable is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the non-halogen flame retardant resin composition which has the high flame retardance and the fall of the electrical property was suppressed is obtained. Moreover, the insulated wire and cable which have high flame retardance and the deterioration of the electrical property was suppressed are obtained.

It is process drawing which shows the manufacturing method of the non-halogen flame retardant resin composition which concerns on one Embodiment of this invention. It is a figure which shows the cross section of the insulated wire which concerns on one Embodiment of this invention. It is a figure which shows the cross section of the cable which concerns on one Embodiment of this invention.

  As described above, the conventional non-halogen flame retardant resin composition contains a polyolefin (sea phase), a crosslinked EVA (island phase), and a metal hydroxide, and the metal hydroxide is a polyolefin (sea phase). ) And crosslinked EVA (island phase). And the metal hydroxide which exists in bridge | crosslinking EVA (island phase) which is an acidic system melt | dissolves, and a void will generate | occur | produce.

  Dispersion of the metal hydroxide in the crosslinked EVA (island phase) occurs when the resin composition is produced by dynamic crosslinking. In the production by dynamic crosslinking, conventionally, polyolefin, uncrosslinked EVA and metal hydroxide are kneaded and dynamic crosslinking is performed. During dynamic crosslinking, the metal hydroxide can be dispersed in the uncrosslinked EVA, and as a result, the metal hydroxide is dispersed in the crosslinked EVA (island phase).

  In this regard, the present inventors have intensively studied and found that the dispersion of the metal hydroxide in the crosslinked EVA (island phase) can be suppressed by changing the timing of adding the metal hydroxide. That is, the polyolefin and uncrosslinked EVA are dynamically crosslinked in advance, and then the metal hydroxide is added to disperse the metal hydroxide into the polyolefin (sea phase), while the crosslinked EVA (island phase). It has been found that the dispersion of can be suppressed. The present invention has been made based on the above findings.

[One Embodiment of the Present Invention]
An embodiment of the present invention will be described below.

(1) Non-halogen flame retardant resin composition The non-halogen flame retardant resin composition according to an embodiment of the present invention is a dynamically cross-linked resin composition, which includes a nonpolar polyolefin (A) as a resin component and an elastomer component. As a non-halogen flame retardant resin composition obtained by dynamically crosslinking a composition containing an ethylene vinyl acetate copolymer having a crosslinkable structure and a metal hydroxide (C). And metal hydroxide (C) exists only in nonpolar polyolefin (A).
That is, the non-halogen flame retardant resin composition according to this embodiment contains a nonpolar polyolefin (A), a silane-crosslinked ethylene vinyl acetate copolymer (B), and a metal hydroxide (C). , Having a sea-island structure in which an island phase containing a silane-crosslinked ethylene-vinyl acetate copolymer (B) is dispersed in a sea phase containing a nonpolar polyolefin (A), and a metal hydroxide (C ) Is dispersed only in the sea phase.

<Non-polar polyolefin>
The nonpolar polyolefin (A) is a resin component and constitutes a sea phase in the non-halogen flame retardant resin composition. In this sea phase, an island phase containing EVA (B) crosslinked with silane and a metal hydroxide (C) are dispersed. Nonpolar polyolefin (A) does not have a polar group, and mainly improves the insulation and water resistance of the non-halogen flame retardant resin composition. The nonpolar polyolefin (A) is not particularly limited as long as it can disperse the silane-crosslinked EVA (B) and the metal hydroxide (C), but the metal hydroxide (C) is filled with a high density. Even if it is a case, it is preferable that it is resin which can be disperse | distributed suitably. The nonpolar polyolefin (A) having excellent dispersibility of the metal hydroxide (C) preferably has a relatively low melting point, for example, a melting point of 140 ° C. or lower. Specifically, high density polyethylene, medium density polyethylene, low density polyethylene, ultra low density polyethylene, ethylene-butene-1 copolymer, ethylene-hexene-1 copolymer, ethylene-octene-1 copolymer, etc. Can be mentioned. A small amount of acid-modified polyolefin or the like may be added to the nonpolar polyolefin (A) for the purpose of improving the adhesion to the metal hydroxide (C). Examples of the acid-modified polyolefin include those obtained by copolymerizing a part of the polyolefin with maleic acid, maleic anhydride, fumaric acid, or the like.

<Silane-crosslinked EVA>
Silane-crosslinked EVA (B) is an elastomer component and constitutes an island phase in the halogen-free flame retardant resin composition. This island phase is dispersed in the sea phase containing the nonpolar polyolefin (A). Silane-crosslinked EVA (B) contains vinyl acetate derived from EVA and mainly improves the flame retardancy of the non-halogen flame retardant resin composition. EVA is deaceticated when heated by a flame to cause an endothermic reaction, thereby suppressing combustion and developing flame retardancy.

  Silane-crosslinked EVA (B) is a crosslinked silane-grafted EVA. Silane grafted EVA is obtained by grafting a silane compound onto EVA and has a structure capable of silane crosslinking.

  EVA contains an acetic acid group and is graft copolymerized with the silane compound by the acetic acid group. The vinyl acetate content of EVA (hereinafter also referred to as VA amount) tends to correspond to the amount of silane compound to be grafted in silane-grafted EVA and corresponds to the degree of crosslinking of silane-crosslinked EVA (B). . When the amount of EVA in EVA is low and the degree of crosslinking of silane-crosslinked EVA (B) is low, the metal hydroxide (C) is likely to be dispersed in silane-crosslinked EVA (B). For this reason, the VA amount of EVA is preferably 20% by mass or more, and more preferably 20% by mass or more and 80% by mass or less.

  The silane compound to be graft copolymerized with EVA is not particularly limited as long as it can introduce a silane crosslinked structure into EVA. Examples of the silane compound include those having a group capable of reacting with EVA and an alkoxy group that forms a silane bridge by silanol condensation.

  The content of the silane-crosslinked EVA (B) is preferably 80:20 to 20:80 in terms of mass ratio of the nonpolar polyolefin (A) and the silane-crosslinked EVA (B), and 70:30 It is more preferable to be ˜30: 70. That is, when the total of the nonpolar polyolefin (A) and the silane-crosslinked EVA (B) is 100 parts by mass, the content of the silane-crosslinked EVA (B) is 20 parts by mass or more and 80 parts by mass or less. It is preferable that it is 30 mass parts or more and 70 mass parts or less. If it is less than 20 parts by mass, it is difficult to obtain sufficient flame retardancy, and if it exceeds 80 parts by mass, the viscosity is high and extrusion molding becomes difficult.

<Metal hydroxide>
The metal hydroxide (C) is a flame retardant and imparts flame retardancy to the non-halogen flame retardant resin composition. Examples of the metal hydroxide (C) include aluminum hydroxide, magnesium hydroxide, and calcium hydroxide. The endothermic amounts at the time of decomposition are about 1000 J / g for calcium hydroxide and 1500 to 1600 J / g for aluminum hydroxide and magnesium hydroxide. For this reason, among the metal hydroxides (C), aluminum hydroxide and magnesium hydroxide are preferable because of their high flame retarding effect.

  The content of the metal hydroxide (C) is preferably 50 parts by mass or more and 300 parts by mass or less with respect to 100 parts by mass in total of (A) and (B). When the content is less than 50 parts by mass, it is difficult to obtain sufficient flame retardancy, and when it exceeds 300 parts by mass, it is difficult to ensure mechanical properties and moldability (extrusion processability).

  The metal hydroxide (C) is preferably subjected to a surface treatment in consideration of dispersibility in the nonpolar polyolefin (A). As the surface treatment, a surface treatment is preferably performed with a silane coupling agent, a titanate coupling agent, a fatty acid such as stearic acid, or the like.

(2) Method for Producing Non-Halogen Flame Retardant Resin Composition A method for producing the non-halogen flame retardant resin composition will be described with reference to FIG. FIG. 1 is a process diagram showing a method for producing a non-halogen flame retardant resin composition according to an embodiment of the present invention.

  The method for producing a non-halogen flame retardant resin composition of the present embodiment contains a nonpolar polyolefin (A), a silane-crosslinked ethylene vinyl acetate copolymer (B), and a metal hydroxide (C). A method for producing a non-halogen flame retardant resin composition, in which a nonpolar polyolefin (A) and an ethylene vinyl acetate copolymer are kneaded, and the ethylene vinyl acetate copolymer is silane-crosslinked to produce a nonpolar polyolefin (A). A step of dispersing the island phase containing the silane-crosslinked ethylene-vinyl acetate copolymer (B) in the sea phase containing, a step of adding and dispersing the metal hydroxide (C) in the sea phase, Have That is, the production method of the present embodiment includes a dynamic crosslinking step of dispersing the silane-crosslinked EVA (B) in the nonpolar polyolefin (A) and a step of dispersing the metal hydroxide (C). It is a separate process.

(Graft copolymerization step S10)
First, prior to dynamic crosslinking, EVA having a structure capable of silane crosslinking is prepared. In this embodiment, silane-grafted EVA is prepared. As shown in S10 of FIG. 1, a silane-grafted EVA is prepared by mixing a silane compound with EVA and performing graft copolymerization. Specifically, graft copolymerization is performed by mixing EVA having a predetermined vinyl acetate content, a silane compound, and a free radical generator, and melt-kneading at a temperature of 100 ° C to 200 ° C. In graft copolymerization, a free radical generator is thermally decomposed by heating to generate radicals, and the silane compound is graft copolymerized with EVA by the radicals. The prepared silane-grafted EVA has a structure capable of silane crosslinking, and is subjected to silane crosslinking in a dynamic crosslinking process described later.

  The VA amount of EVA to be used is not particularly limited, but is preferably 20% by mass or more, and more preferably 20% by mass or more and 80% by mass or less. By using EVA with a relatively large amount of VA, the grafting rate of the silane compound in the silane-grafted EVA can be increased. Then, when the silane-grafted EVA is crosslinked, the degree of crosslinking of the silane-crosslinked EVA (B) can be improved, and mixing of the metal hydroxide (C) can be suppressed.

  Although the addition amount of a silane compound is not specifically limited, It is preferable to set it as 0.5 to 10 mass parts with respect to 100 mass parts of EVA. When the amount is less than 0.5 parts by mass, introduction of a silane cross-linked structure into EVA is reduced, and it becomes difficult to obtain a sufficient effect of silane cross-linking. On the other hand, if it exceeds 10 parts by mass, the workability tends to decrease.

  Examples of the silane compound include vinyl silane compounds such as vinyl trimethoxy silane, vinyl triethoxy lane, vinyl tris (β-methoxy ethoxy) silane, γ-aminopropyl trimethoxy silane, γ-aminopropyl triethoxy silane, N-β-. Aminosilane compounds such as (aminoethyl) γ-aminopropyltrimethoxysilane, β- (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, β- (3,4 epoxy cyclohexyl) Epoxy silane compounds such as ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, acrylic silane compounds such as γ-methacryloxypropyltrimethoxysilane, bis ( -(Triethoxysilyl) propyl) disulfide, polysulfide silane compounds such as bis (3- (triethoxysilyl) propyl) tetrasulfide, mercaptosilane compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, etc. Can be mentioned.

  As the free radical generator, for example, an organic peroxide such as dicumyl peroxide can be used. The addition amount of the free radical generator is preferably 0.001 parts by mass or more and 3.0 parts by mass or less with respect to 100 parts by mass of EVA. When it is less than 0.001 part by mass, it becomes difficult to graft copolymerize the silane compound with EVA, and it becomes difficult to obtain a sufficient effect of silane crosslinking. When the amount exceeds 3.0 parts by mass, EVA scorch tends to occur during subsequent kneading.

(Dynamic cross-linking step S20)
Next, as shown in S20 of FIG. 1, the resin mixture containing the uncrosslinked silane-grafted EVA obtained above, the nonpolar polyolefin (A), and the silanol condensation catalyst is kneaded to perform dynamic crosslinking. Do. In this step, the metal hydroxide (C) may not be added to the uncrosslinked silane-grafted EVA, so the metal hydroxide (C) is not added.

  Specifically, uncrosslinked silane-grafted EVA is dispersed in nonpolar polyolefin (A) by kneading the resin mixture, and silane-grafted EVA is dispersed in the sea phase containing nonpolar polyolefin (A). A resin mixture having a sea-island structure in which the island phase is dispersed. As the silane crosslinking proceeds simultaneously with this kneading, the uncrosslinked silane-grafted EVA becomes a crosslinked EVA (B). In silane crosslinking, uncrosslinked silane-grafted EVA undergoes silanol condensation reaction to cause crosslinking. On the other hand, since the nonpolar polyolefin (A) does not have a crosslinkable structure, it will remain uncrosslinked.

  In the dynamic crosslinking step S20, the kneading conditions and temperature conditions are not particularly limited, but it is sufficient that sufficient crosslinking and dispersion have progressed. For example, it is preferable to use a twin screw extruder capable of providing a high shear field to perform dynamic crosslinking at a temperature of about 180 ° C. as a temperature at which crosslinking proceeds rapidly and no molecular deterioration occurs.

  The mixing ratio of the nonpolar polyolefin (A) and the uncrosslinked silane grafted EVA is adjusted so that the mass ratio of the nonpolar polyolefin (A) and the silane crosslinked EVA (B) is a predetermined ratio. .

  As the silanol condensation catalyst, for example, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctate, stannous acetate, zinc caprylate, lead naphthenate, cobalt naphthenate and the like are used. The addition amount of the silanol condensation catalyst is not particularly limited, but is preferably 0.001 part by mass or more and 0.1 part by mass or less with respect to 100 parts by mass of the uncrosslinked silane-grafted EVA.

(Metal hydroxide kneading step S30)
Next, as shown in S30 of FIG. 1, the metal hydroxide (C) is added to the resin mixture obtained in S20 and kneaded to disperse the metal hydroxide (C). A flame retardant resin composition is produced. Of the resin mixture obtained in S20, the nonpolar polyolefin (A) is uncrosslinked and becomes a fluid component, whereas the silane crosslinked EVA (B) is crosslinked and becomes a solid component. For this reason, the metal hydroxide (C) is dispersed in the nonpolar polyolefin (A), but is not dispersed in the silane-crosslinked EVA (B).

  By the above process, the nonpolar polyolefin (A), the silane-crosslinked ethylene vinyl acetate copolymer (B), and the metal hydroxide (C) are contained, and the sea containing the nonpolar polyolefin (A) is contained. The phase has a sea-island structure in which an island phase containing a silane-crosslinked ethylene-vinyl acetate copolymer (B) is dispersed, and the metal hydroxide (C) is dispersed only in the sea phase. A non-halogen flame retardant resin composition can be obtained.

  In the dynamic crosslinking step S20 or the metal hydroxide kneading step S30, other additives may be added as necessary. Other additives include cross-linking agents, cross-linking aids, flame retardant aids, UV absorbers, light stabilizers, softeners, lubricants, colorants, reinforcing agents, surfactants, inorganic fillers, plasticizers, metal chelates. Agents, foaming agents, compatibilizers, processing aids, stabilizers and the like.

(3) Insulated wire Next, an insulated wire provided with an insulating layer made of the above halogen-free flame retardant resin composition on the outer periphery of the conductor will be described with reference to FIG. FIG. 2 is a view showing a cross section of an insulated wire according to an embodiment of the present invention.

  The insulated wire 1 of the present embodiment has a conductor 10 and an insulating layer 11 formed on the outer periphery of the conductor 10, and the insulating layer 11 is made of the above-described non-halogen flame retardant resin composition.

  As the conductor 10, in addition to a copper wire made of low-oxygen copper, oxygen-free copper or the like, a copper alloy wire, other metal wires such as silver are used. In FIG. 2, the cross-sectional shape of the conductor 10 is a circular shape, but the present invention is not limited to this, and may be, for example, a quadrangular shape (including those having four curved corners). Moreover, the conductor diameter of the conductor 10 is not specifically limited, The optimal numerical value is suitably selected according to a use.

  The insulating layer 11 is made of the non-halogen flame retardant resin composition. The insulating layer 11 is formed by extrusion-coating a non-halogen flame retardant resin composition so as to have a predetermined thickness on the outer periphery of the conductor 10. The thickness of the insulating layer 11 is not particularly limited, and an optimal value is appropriately selected according to the application.

(4) Cable Next, refer to FIG. 3 for a cable provided with a sheath made of the above-mentioned non-halogen flame retardant resin composition and an insulated wire having an insulating layer on the outer periphery of the conductor or a core formed by twisting a plurality of insulated wires While explaining.

  As shown in FIG. 3, the cable 2 of the present embodiment includes an insulated wire 1 having an insulating layer 11 on the outer periphery of a conductor 10 and a sheath 12, and the sheath is the non-halogen flame-retardant resin composition. It is made up of. The sheath is formed by extrusion coating a non-halogen flame retardant resin composition so as to have a predetermined thickness on the outer periphery of the core. The thickness of the sheath is not particularly limited, and an optimal value is appropriately selected according to the application.

  FIG. 3 shows a cable having one insulated wire as a core, but the number of insulated wires constituting the core is not particularly limited. Further, the insulated wire constituting the core of the cable is not particularly limited, and an insulated wire provided with an insulating layer made of the non-halogen flame retardant resin composition, or an insulated wire provided with an insulating layer made of a known rubber composition is used. be able to.

  In addition, although the insulated wire shown in FIG. 2 or the cable shown in FIG. 3 has a single layer structure, an outermost layer may be provided on the insulating layer 11 or the sheath 12 to have a multilayer structure. The material used for the outermost layer is not particularly limited. Moreover, you may give a separator, a braiding, etc. to an insulated wire or a cable as needed.

[Effect of this embodiment]
According to the present embodiment, the following one or more effects are achieved.

  According to the non-halogen flame retardant resin composition of the present embodiment, the metal hydroxide (C) is dispersed only in the sea phase containing the nonpolar polyolefin (A), and the silane-crosslinked EVA (B) is dispersed. It does not exist in the island phase. Thereby, in the silane-crosslinked EVA (B) which is an acidic system, generation of voids due to the dissolution of the metal hydroxide (C) is suppressed. And since generation | occurrence | production of a void is suppressed, high insulation is hold | maintained.

  Further, according to the non-halogen flame retardant resin composition of the present embodiment, since the metal hydroxide (C) is not present in the silane-crosslinked EVA (B), the metal hydroxide (C) is high-density. The flame retardancy can be improved.

  In the present embodiment, the silane-crosslinked EVA (B) is preferably a silane-crosslinked EVA having a vinyl acetate content of 20% by mass. This increases the degree of crosslinking of the silane-crosslinked EVA (B) and further suppresses the dispersion of the metal hydroxide (C) in the silane-crosslinked EVA (B).

  In the present embodiment, the nonpolar polyolefin (A) and the silane-crosslinked EVA (B) are contained in a mass ratio (A: B) in a ratio within a range of 70:30 to 30:70. It is preferable to contain 50 to 300 parts by mass of the metal hydroxide (C) with respect to 100 parts by mass in total of A) and (B). Thereby, a mechanical characteristic and extrusion workability can be improved with the improvement of a flame retardance and suppression of the fall of insulation performance.

  In addition, according to the production method of the present embodiment, a dynamic crosslinking step of dispersing the silane-crosslinked EVA (B) in the nonpolar polyolefin (A), and a step of dispersing the metal hydroxide (C) , Is a separate process. Thereby, dispersion | distribution of the metal hydroxide (C) to EVA (B) silane-crosslinked can be suppressed.

  Moreover, according to this embodiment, the insulation layer of an insulated wire or the sheath of a cable is comprised from the said non-halogen flame-retardant resin composition. As a result, it is possible to obtain an insulated wire and a cable that have high flame retardancy and in which deterioration of electrical characteristics over time is suppressed.

[Other Embodiments]
In the above embodiment, another polymer component may be included in addition to the nonpolar polyolefin (A) and the silane-crosslinked EVA (B).

  Moreover, although the said embodiment demonstrated the case where the nonpolar polyolefin (A) was a non-crosslinked non-halogen flame retardant resin composition, the present invention is not limited to this. In order to obtain higher heat resistance, the non-polar polyolefin (A) may be cross-linked to completely cross-link the non-halogen flame retardant resin composition. The crosslinking method in this case is not particularly limited, and crosslinking can be performed by organic peroxide crosslinking, electron beam irradiation, UV irradiation, or the like.

  Moreover, although the said embodiment demonstrated the case where a non-halogen flame-retardant resin composition was used for the insulation layer of an insulated wire, or the sheath of a cable, this invention is not limited to this. The non-halogen flame retardant resin composition can be applied to, for example, tubes, hoses, films, sheets, rollers, containers, bags, packings, electric wires, cords, optical fibers, optical cords, membranes, filters, tapes, belts and the like.

  Next, examples of the present invention will be described. In this example, a halogen-free flame retardant resin composition was prepared, and a cable was produced using the composition. And the non-halogen flame retardant resin composition was evaluated by evaluating the manufactured cable. These examples are examples of the non-halogen flame retardant resin composition and cable according to the present invention, and the present invention is not limited to these examples.

(Examples 1-9)
A non-halogen flame retardant resin composition was prepared by the method described below to produce a cable.

<Adjustment of silane-grafted EVA>
First, the silane grafted EVA used in this example was prepared. As EVA, 3 parts by mass of vinyl trimethoxysilane (Syra Ace S210, manufactured by Chisso) as a silane compound with respect to 100 parts by mass of EVA (VF120S, made by Ube Maruzen Polyethylene) with a vinyl acetate content of 20% by mass 0.01 parts by mass of dicumyl peroxide (manufactured by NOF Corporation) as a radical generator was added and mixed, and these mixtures were mixed into a 40 mm single screw extruder (L / D = The silane grafted EVA was prepared by graft reaction in 24).

<Adjustment of non-halogen flame retardant resin composition>
Next, the silane-grafted EVA prepared above, an ethylene α-olefin copolymer as a nonpolar polyolefin (A) (Tuffma A1070S, manufactured by Mitsui Chemicals), and dibutyltin laurate (TN-12) as a silanol condensation catalyst , Manufactured by Sakai Chemical Industry Co., Ltd.) at a predetermined blending ratio, and the mixture was kneaded by a twin screw extruder (L / D = 60) having a screw diameter of 41 mm. By kneading, the silane-grafted EVA was silane-crosslinked by dynamic crosslinking to obtain a pelletized mixture having a sea-island structure of nonpolar polyolefin (A) and silane-crosslinked EVA (B). In addition, as kneading | mixing conditions, the cylinder temperature was set to 180 degreeC and the screw speed was set to 300 rpm.

  Subsequently, the kneaded product and the metal hydroxide (C) obtained above were mixed at a predetermined blending ratio, and the mixture was kneaded with a 3 L kneader set at 50 ° C. After raising the temperature to 0 ° C., it was dropped to prepare the non-halogen flame retardant resin composition of this example. As the metal hydroxide (C), magnesium hydroxide (Kisuma 5L, manufactured by Kyowa Chemical) or aluminum hydroxide (BF013STV, manufactured by Nippon Light Metal) was used.

  The adjustment conditions of the non-halogen flame retardant resin compositions of Examples 1 to 9 are shown in Table 1 below.

  In Examples 1 to 4, non-halogen flame retardant resin compositions were prepared by appropriately changing the addition amount ratio (mass ratio A: B) of nonpolar polyolefin (A) and silane-crosslinked EVA (B). Specifically, the mass ratio A: B was changed to 20:80 in Example 1, 30:70 in Example 2, 70:30 in Example 3, and 80:20 in Example 4. . In Examples 1 to 4, the amount added of the silanol condensation catalyst is appropriately changed so as to be 0.05 parts by mass with respect to 100 parts by mass of the silane-grafted EVA.

  In Examples 5 to 8, the addition ratio (mass ratio A: B) of the nonpolar polyolefin (A) and the silane-crosslinked EVA (B) was fixed at 30:70, and the metal hydroxide (C) The amount of magnesium hydroxide added was appropriately changed. Specifically, the addition amount of the metal hydroxide (C) is 40 parts by mass in Example 5, 50 parts by mass in Example 6, 300 parts by mass in Example 7, and 310 parts by mass in Example 8, respectively. changed. Moreover, in Example 9, it adjusted on the conditions similar to Example 2 except having changed the kind of metal hydroxide (C) into aluminum hydroxide.

<Manufacture of cables>
Next, the cables of Examples 1 to 9 were manufactured using the non-halogen flame retardant resin compositions of Examples 1 to 9 prepared above. Specifically, using a single screw extruder (L / D = 24) with a screw diameter of 40 mm set at a cylinder temperature of 180 ° C., the non-halogen flame retardant resin composition is 0.45 mm thick on the cable core. The cable was manufactured by extrusion coating to form a coating layer (sheath). In addition, as a cable core, what twisted 80 tin-plated conductors with an outer diameter of 0.40 mm was used.

<Evaluation of cable>
Next, with respect to the cables of Examples 1 to 9 manufactured as described above, various characteristics of the sheath of the cable were evaluated by the test methods shown below. Each will be described below.

(Evaluation of phase structure)
A thin film slice (0.45 mm × 2.0 mm × 2.0 mm) cut from the sheath was dyed with ruthenium tetroxide, and the cut surface of the thin film slice was sputtered by the FIB (focused ion beam) method. Thereafter, the sputtered surface of the thin film slice was observed for cross-section by SEM (differential scanning electron microscope). At this time, a bright image is observed because the EVA phase is dyed with ruthenium tetroxide, while a dark image is observed in the nonpolar polyolefin phase. By cross-sectional observation, the presence or absence of metal hydroxide in the silane-crosslinked EVA phase was confirmed. Evaluation was performed according to the following criteria.
○: Mixing of metal hydroxide into the EVA phase is not confirmed ×: Mixing of metal hydroxide into the EVA phase is confirmed

  When the phase structures of the sheaths of the cables of Examples 1 to 9 were evaluated, the inclusion of the metal hydroxide (C) in the EVA phase was not confirmed in any of the sheaths and was “◯”.

(Evaluation of electrical characteristics)
In accordance with EN50264-3-1 (Section 7.7), the cable was immersed in 3% salt water at 85 ° C. and subjected to a DC stability test in which 1.5 kV minus electricity was applied. Evaluation was performed according to the following criteria.
○: No short circuit in 10 days ×: Short circuit in less than 10 days

  When the electrical characteristics of the cable sheaths of Examples 1 to 9 were evaluated, it was confirmed that no short circuit occurred in 10 days in any of the cables, and it was confirmed that the electrical characteristics were excellent.

(Evaluation of extrusion processability)
The non-halogen flame retardant resin composition was carried out at the maximum take-off speed when extrusion was carried out with a single screw extruder having a screw diameter of 40 mm. Evaluation was performed according to the following criteria.
A: Maximum take-up speed is 20 m / min or more. O: Maximum take-up speed is 1 m / min or more and less than 20 m / min.

  The non-halogen flame retardant resin compositions of Examples 1 to 9 were evaluated for extrusion processability. As a result, Example 1 was “◯” and Examples 2 to 8 were “◎”.

(Evaluation of flame retardancy)
The cable was subjected to a vertical flame retardant test in accordance with EN60332-1-2, and self-extinguishing was designated as “◎”. A cable that failed the vertical flame retardant test was subjected to a 60-degree inclined combustion test based on JISC3005, and the self-extinguishing test was designated as “◎”. A horizontal combustion test based on JISC3005 was performed on the cable that failed the 60-degree inclined combustion test, and the self-digested product was rated as “◯”. Those that failed all the combustion tests were marked “x”.

  When the flame retardancy of the sheath was evaluated for the cables of Examples 1 to 9, Examples 1, 2, and 7 to 9 were “「 ”, and Examples 3 and 6 were“ ◎ ”. Examples 4 and 5 were “◯”.

(Evaluation of growth rate)
A thin film section was cut from the sheath of the cable and punched out into a No. 6 dumbbell test piece, and thereafter, the tensile speed was 200 mm / min and the distance between the evaluation lines was 20 mm. Evaluation was performed according to the following criteria.
◎: Elongation rate is 200% or more ○: Elongation rate is 150% or more and less than 200% ×: Elongation rate is less than 150%

  When the elongation rate of the cables of Examples 1 to 9 was evaluated, it was 200% or more and “◎” except that Example 8 was 150% or more and less than 200% and “◯”. .

(Comprehensive evaluation)
Based on the result of the evaluation method, comprehensive evaluation was performed. Evaluation was performed according to the following criteria.
◎: Particularly good in all evaluations ○: Does not include x in all evaluations X: Includes x in any evaluation

  The overall evaluation of the cables of Examples 1 to 9 was ◎ or ○, and it was confirmed that the cables had good characteristics. The above evaluation results are shown in Table 2 below.

(Comparative Example 1)
In Comparative Example 1, the type of silane-grafted EVA was changed, and silane-grafted EVA obtained by grafting a silane compound to EVA having a vinyl acetate content of 19% by mass (EV460, manufactured by Mitsui DuPont Chemical Co., Ltd.) was used. Except for the above, a non-halogen flame retardant resin composition was prepared under the same production conditions as in Example 2 to produce a cable. The adjustment conditions of Comparative Example 1 are shown in Table 3 below.

  The cable of Comparative Example 1 was evaluated in the same manner as in the example. As a result, in the phase structure evaluation, magnesium hydroxide particles are mixed not only in the non-polar polyolefin phase (sea phase) that is observed dark in cross-sectional observation but also in the EVA phase (island phase) that is observed brightly. It was confirmed that Moreover, in the evaluation of electrical characteristics, it was confirmed that a short circuit occurred in one day as a result of the direct current stability test. The evaluation results of Comparative Example 1 are shown in Table 4 below.

(Comparative Example 2)
In Comparative Example 2, a non-halogen flame retardant resin composition was prepared under the same conditions as in Example 2 except that the timing of adding the metal hydroxide (C) was changed.
Specifically, 70 parts by mass of the prepared silane graft EVA, 30 parts by mass of the nonpolar polyolefin (A), 0.035 parts by mass of the silanol condensation catalyst, and magnesium hydroxide as the metal hydroxide (C) The non-halogen flame retardant resin composition was prepared by adding 200 parts by mass of kneading and kneading EVA with silane crosslinking.

  The cable of Comparative Example 2 was evaluated in the same manner as in the example. As a result, in the phase structure evaluation, magnesium hydroxide particles are mixed not only in the non-polar polyolefin phase (sea phase) that is observed dark in cross-sectional observation but also in the EVA phase (island phase) that is observed brightly. It was confirmed that Moreover, in the evaluation of electrical characteristics, it was confirmed that a short circuit occurred in one day as a result of the direct current stability test.

1 Insulated wire 2 Cable 10 Conductor 11 Insulating layer 12 Sheath

Claims (6)

A nonpolar polyolefin (A);
A silane-crosslinked ethylene vinyl acetate copolymer (B);
A metal hydroxide (C),
In the sea phase containing the nonpolar polyolefin (A), the island phase containing the silane-crosslinked ethylene vinyl acetate copolymer (B) has a sea-island structure,
The halogen-free flame retardant resin composition, wherein the metal hydroxide (C) is dispersed only in the sea phase. The non-halogen according to claim 1, wherein the silane-crosslinked ethylene vinyl acetate copolymer (B) is obtained by silane-crosslinking an ethylene vinyl acetate copolymer having a vinyl acetate content of 20% by mass or more. Flame retardant resin composition. The nonpolar polyolefin (A) and the silane-crosslinked ethylene vinyl acetate copolymer (B) are contained in a mass ratio (A: B) in a ratio within a range of 70:30 to 30:70,
2. The non-halogen according to claim 1, wherein the metal hydroxide (C) is contained in an amount of 50 parts by mass to 300 parts by mass with respect to a total of 100 parts by mass of the (A) and the (B). Flame retardant resin composition. A method for producing a non-halogen flame retardant resin composition comprising a nonpolar polyolefin (A), a silane-crosslinked ethylene vinyl acetate copolymer (B), and a metal hydroxide (C),
The non-polar polyolefin (A) and the ethylene vinyl acetate copolymer are kneaded and the ethylene vinyl acetate copolymer is silane-crosslinked, so that the silane cross-linking is carried out in the sea phase containing the non-polar polyolefin (A). A step of dispersing an island phase containing the prepared ethylene vinyl acetate copolymer (B);
Adding and dispersing the metal hydroxide (C) in the sea phase;
A process for producing a halogen-free flame retardant resin composition, comprising: An insulated wire comprising an insulating layer comprising the non-halogen flame retardant resin composition according to any one of claims 1 to 3 on an outer periphery of a conductor. A sheath composed of the non-halogen flame retardant resin composition according to any one of claims 1 to 3 is provided on an insulated wire having an insulating layer on an outer periphery of a conductor or a core formed by twisting a plurality of the insulated wires. Cable characterized by.

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