JP2014065809A - Non-halogen flame-retardant resin composition, molded article and non-halogen flame-retardant insulation wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-halogen flame-retardant resin composition, a molded article and a non-halogen flame-retardant insulation wire having high flame resistance, excellent in heat resistance, mechanical property, flexibility, peeling property and whitening resistance due to rubbing, and capable of being manufactured at low cost.SOLUTION: A non-halogen flame-retardant resin composition, a molded article and a non-halogen flame-retardant insulation wire contain (a) 20 to 40 mass% of ethylene propylene rubber having a content of ethylene component of 50 to 75 mass%, (b) 30 to 50 mass% of ethylene-vinyl acetate copolymer having a content of vinyl acetate component of 40 mass% or less, and (c) 50 to 120 pts.mass of aluminum hydroxide based on 100 pts.mass of a base resin component containing 10 to 40 mass% of ultra low density polyethylene having a crystallinity of 40% or less.

Description

  The present invention relates to a halogen-free flame retardant resin composition, a molded article, and a halogen-free flame retardant insulated wire.

Insulated wires used for internal and external wiring of various devices are required to have high flame resistance, wear resistance (whitening resistance) in addition to heat resistance, mechanical properties, and flexibility.
Generally, when a current is passed through an insulated wire, the conductor generates heat, and the temperature of the entire insulated wire increases accordingly. For this reason, an insulated wire used as a wiring material in a sealed container or the like is required to have heat resistance and to have little deterioration in mechanical properties after a heat aging test. Moreover, it is required to have mechanical characteristics that do not break due to stress when laying an insulated wire. In addition, it is necessary to have good flexibility in bending work of the electric wire when installing the electric wire in a curved tube in a facility where the machine parts and electric parts are densely packed such as in the switchboard. . In order to impart flame retardancy to a non-halogen flame retardant resin composition, it is known to add a large amount of metal hydrate as a flame retardant. When the wire is manufactured or laid, the surface of the insulated wire is rubbed to cause scratches on the surface. This causes a whitening phenomenon called whitening, and this whitening phenomenon not only impairs the appearance of the insulated wire, but is also severely damaged. Since there is a possibility of impairing electrical characteristics, a wear-resistant insulated wire is required.
Conventionally, as a flame-retardant insulated electric wire having heat resistance and excellent mechanical strength and flexibility, one using chlorinated polyethylene as a base resin constituting a coating layer has been used. However, although chlorinated polyethylene is excellent in flame retardancy, heat resistance, mechanical strength and flexibility, it has a large environmental load. For this reason, research on non-halogen flame retardant resin compositions has been actively conducted in recent years.

  Use of a mixed resin of ethylene / propylene rubber, ethylene-vinyl acetate copolymer and polyethylene as a resin to replace chlorinated polyethylene, and use of a metal hydroxide as a flame retardant (for example, Patent Documents 1 to 3) reference). In particular, the non-halogen flame retardant resin composition proposed in Patent Document 3 is excellent in flame retardancy, heat resistance, and mechanical strength, but is required to further improve the whitening resistance due to peelability and rubbing. It was. Also, development of an inexpensive non-halogen flame retardant resin composition has been demanded.

JP-A-2-115249 JP 2002-31803 A JP 2012-82277 A

  The present invention solves the above-mentioned problems, and has high flame resistance, heat resistance, mechanical properties, flexibility, whitening resistance due to abrasion and rubbing, and non-halogen flame resistance that can be produced at low cost. It is an object to provide a resin composition, a molded article, and a non-halogen flame-retardant insulated electric wire.

  In the above-mentioned Japanese Patent Application Laid-Open No. 2012-82277, in order to compensate for the poor compatibility of the mixed resin of (a) ethylene / propylene rubber and (b) ethylene-vinyl acetate copolymer, maleic acid-modified linear low Abrasion resistance is improved by including a density polyethylene resin. However, in the study by the present inventors, the combination of only (a) and (b) is not so good in compatibility between resins, so that the wear resistance is reduced and the whitening phenomenon that occurs when the wire coating layer is rubbed is remarkable. It turns out that it appears.

As a result of intensive studies on the above problems, the present inventors have found that even if the content of ethylene / propylene rubber is low, the composition and content of the polyethylene resin, and the combined ethylene-vinyl acetate copolymer, The present inventors have found that the whitening resistance due to rubbing is greatly affected, and have studied the relationship between the combination of these flame retardant resin components and the above characteristics in detail, thereby reaching the present invention.
That is, in the present invention, compatibility with ethylene / propylene rubber or ethylene-vinyl acetate copolymer is improved by adding ultra-low density polyethylene without adding maleic acid-modified linear low density polyethylene resin. In addition, the softness close to that of a synthetic rubber can be provided, which is effective for the whitening resistance.

Therefore, the above-mentioned subject was achieved by the following means.
<1> (a) 20 to 40% by mass of ethylene / propylene rubber having an ethylene component content of 50 to 75% by mass, and (b) 30 ethylene-vinyl acetate copolymer having a vinyl acetate component of 40% by mass or less. And 50 to 120 parts by mass of aluminum hydroxide with respect to 100 parts by mass of base resin component containing 10 to 40% by mass of ultra-low density polyethylene having a crystallinity of 40% or less. Non-halogen flame retardant resin composition characterized.
<2> The non-halogen flame retardant resin composition according to <1>, wherein the component (a) is ethylene / propylene / diene rubber.
<3> The halogen-free flame-retardant resin composition according to <1> or <2>, wherein the content of the diene component in the rubber of the component (a) is 3 to 10% by mass.
<4> The rubber according to any one of <1> to <3>, wherein the diene component is a dicyclopentadiene component or a 5-ethylidene-2-norbornene component in the rubber of the component (a). Non-halogen flame retardant resin composition.
<5> The halogen-free flame retardant according to any one of <1> to <4>, wherein the density of the ultra-low density polyethylene of the component (c) is 0.91 g / cm ³ or less. Resin composition.
<6> The melting temperature of the ultra-low density polyethylene of component (c) by a differential scanning calorimeter (DSC) is 30 to 120 ° C., according to any one of <1> to <5> The non-halogen flame retardant resin composition described.
<7> The non-halogen flame retardant resin composition according to any one of <1> to <6>, further comprising a crosslinking agent or / and a crosslinking aid.
<8> A molded article obtained by crosslinking the non-halogen flame retardant resin composition according to any one of <1> to <7>.
<9> A coating layer formed using the non-halogen flame retardant resin composition according to any one of <1> to <7> is directly or indirectly provided on the outer periphery of the conductor, and the coating layer is crosslinked. Non-halogen flame retardant insulated wire.

  According to the present invention, non-halogen flame retardant resin composition which is excellent in heat resistance, mechanical properties, flexibility, whitening resistance (abrasion resistance) due to rubbing and rubbing with high flame retardancy, and can be produced at low cost. Products, molded articles and non-halogen flame retardant insulated wires can be provided.

It is the schematic sectional drawing shown typically about one embodiment of the non-halogen flame-retardant insulated wire of this invention. It is the schematic sectional drawing typically shown about other one embodiment of the non-halogen flame-retardant insulated wire of this invention. It is the schematic sectional drawing which showed typically about another one embodiment of the non-halogen flame-retardant insulated wire of this invention.

A preferred non-halogen flame retardant insulated wire of the present invention will be described with reference to the drawings.
FIG. 1 is a non-halogen flame retardant insulated wire showing a preferred embodiment of an insulated wire 10 using a non-halogen flame retardant resin composition of the present invention described later as an outermost layer. As shown in FIG. 1, in the non-halogen flame retardant insulated wire of the present invention, a coating layer made of the non-halogen flame retardant resin composition of the present invention is formed directly on a conductor 1, and the coating layer is crosslinked. By doing so, the crosslinked coating layer 3 is formed.
FIG. 2 is a non-halogen flame retardant insulated electric wire which shows an insulated wire 20 using the non-halogen flame retardant resin composition of the present invention described later as an outermost layer as another preferred embodiment. As shown in FIG. 2, in the non-halogen flame retardant insulated wire 20 of the present invention, the outer layer is coated with the non-halogen flame retardant resin composition of the present invention on the conductor 1 through the other layer 2. A layer is formed, and the coating layer is crosslinked to form a crosslinked coating layer 3. As the other layer 2, a material in which a separator such as a polyester tape or a nylon tape is wound can be used.
Furthermore, FIG. 3 is a non-halogen flame retardant insulated electric wire showing an insulated wire 30 using the non-halogen flame retardant resin composition of the present invention described later as still another preferred embodiment. As shown in FIG. 3, the non-halogen flame retardant insulated wire 30 of the present invention has an inner conductive layer 5 formed on a conductor 1, a coating layer 4 formed on the inner conductive layer 5, and further on the coating layer. Further, a crosslinked coating layer 3 using the non-halogen flame retardant resin composition of the present invention is formed as a sheath layer. The coating layer 4 of FIG. 3 may use the non-halogen flame retardant resin composition of the present invention.

<< Non-halogen flame retardant resin composition >>
The non-halogen flame retardant resin composition of the present invention is obtained by blending aluminum hydroxide with a base resin component containing an ethylene / propylene rubber, an ethylene-vinyl acetate copolymer and ultra-low density polyethylene.

(A) Ethylene / propylene rubber In the present invention, ethylene / propylene rubber means both EPDM, which is a terpolymer of ethylene, propylene and non-conjugated diene, and EPM, which is a copolymer of ethylene and propylene. .
The ethylene / propylene rubber used in the present invention has an ethylene component content of 50 to 75 mass%. By making content of an ethylene component into this range, while improving the workability at the time of kneading | mixing or extrusion, mechanical strength can be improved. If the ethylene content is too low, sufficient mechanical properties, particularly tensile strength, cannot be obtained. If the ethylene content is too high, the resin composition becomes too hard.
The content of the ethylene component is preferably 50 to 70% by mass, more preferably 50 to 65% by mass, further preferably 55 to 65% by mass, and particularly preferably 55 to 60% by mass.
In the present invention, among EPDM which is a terpolymer of ethylene, propylene and non-conjugated diene and EPM which is a copolymer of ethylene and propylene, a terpolymer of ethylene, propylene and non-conjugated diene is used. Some EPDMs are preferred.

The diene component in EPDM, which is a terpolymer of ethylene, propylene and a non-conjugated diene, is dicyclopentadiene (DCPD), 5-ethylidene-2-norbornene (ENB), vinylidene norbornene (VNB) and 1,4-hexadiene. (HD or 1,4-HD), and these diene components may be used alone or in combination of two or more.
1-15 mass% is preferable and, as for content of a diene component, 3-10 mass% is more preferable.

As EPM, Mitsui EPT0045 (manufactured by Mitsui Chemicals), JSR EP11, T7942, EP01P, EP02P, EP07P, EP912P, EP922P, EP941P, EP961SP (above, manufactured by JSR Corporation), etc. EPDMs using DCPD as a diene include Mitsui EPT1035, 1045, 1070, 1070L (above, Mitsui Chemicals), JSR EP75F (JSR), etc. EPDMs using ENB as dienes include Mitsui EPT3012P, 3042E, 3045, 3070, 3062E, 3072E, 3085, 3091, 3090E, 3095, 4010, 4021, 14030. , 4045, 4070, 095, 8075E (Mitsui Chemicals, Inc.), JSR EP43, EP93, EP21, EP22, EP24, EP25, EP27, EP51, EP57F, EP57C, EP103AF, EP107F T7141, EP33, EP35, EP35F, EP37F, EP65, EP57P, EP96, EP98, T7501EF, EP503EF (manufactured by JSR Co., Ltd.), etc., and DCPD and ENB are copolymerized Examples of the EPDM are JSR T7881F, EP801E (above, manufactured by JSR Corporation), and the like.
In the present invention, these may be used alone or in combination of two or more.

The content of the ethylene / propylene rubber in the resin component is 20 to 40% by mass. By setting the content within this range, an increase in the hardness of the resin composition can be suppressed and flexibility can be imparted. If it is less than this range, it will be too hard, and if it is too much, the mechanical strength will be insufficient.
The content of ethylene / propylene rubber is preferably 20 to 30% by mass.

(B) Ethylene-vinyl acetate copolymer The ethylene-vinyl acetate copolymer used in the present invention has a vinyl acetate component content of 40% by mass or less. When there is too much content of a vinyl acetate component, tensile strength will fall.
5-40 mass% is preferable, as for content of a vinyl acetate component, 5-30 mass% is more preferable, and 10-25 mass% is further more preferable. In addition, when there is too little content of a vinyl acetate component, a flame retardance may fall.
Content of the ethylene-vinyl acetate copolymer in a resin component is 30-50 mass%, By making it in this range, tensile strength can be made high, ensuring a flame retardance. If the content of the ethylene-vinyl acetate copolymer is too low, sufficient flame retardancy cannot be obtained, and if it is too high, it becomes too hard.

(C) Very Low Density Polyethylene The ultra low density polyethylene (VLDPE) used in the present invention has a crystallinity of 40% or less. By setting the crystallinity within this range, softness close to that of synthetic rubber can be obtained. When the degree of crystallinity exceeds 40%, it may become hard and the rigidity may be increased.
The crystallinity is preferably 1 to 40%, more preferably 10 to 30%, still more preferably 15 to 25%. Here, the crystallinity is a value measured by DSC (differential scanning calorimeter) or X-ray diffraction method.
The density of the ultra-low density polyethylene used in the present invention is preferably 0.91 g / cm ³ or less, more preferably 0.86 to 0.91 g / cm ³ , and still more preferably 0.865 to 0.91 g. / Cm ³ , particularly preferably 0.870 to 0.905 g / cm ³ .
Here, the density is a density measured in accordance with JIS K6922-2.
Moreover, 30-120 degreeC is preferable and, as for the melting temperature by a differential scanning calorimeter (DSC), More preferably, it is 60-110 degreeC.

The ultra-low density polyethylene is a copolymer of ethylene and an α-olefin, and the α-olefin is a carbon number such as propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene. 3-12 alpha olefins are preferred.
Ultra-low density polyethylene is manufactured with multi-site type catalysts such as Ziegler-type catalysts and Phillips-type catalysts, single-site type catalysts such as metallocene-type catalysts, CGC-type catalysts, etc., and is not limited to catalysts, production methods, etc. However, an ethylene-α-olefin copolymer obtained with a catalyst including a metal complex coordinated with a ligand having a cyclopentadienyl skeleton is preferable.
Examples of the ultra-low density polyethylene include Exact (exxon), affinity, Engage (made by Dow Elastomer), Kernel (made by Nippon Polyethylene), and the like.

The content of the ultra-low density polyethylene in the resin component is 10 to 40% by mass. By making this range, even if the ethylene / propylene rubber content is low, it contains a large amount of ethylene / propylene rubber. Thus, it is possible to maintain flexibility that is supple and soft. If the content of the ultra-low density polyethylene is too small, the whitening phenomenon that occurs when the coating surface is rubbed cannot be suppressed, and if it is too much, the tensile strength may be lowered.
In the present invention, the content of the ultra-low density polyethylene is preferably 20 to 40% by mass.

  In the present invention, ultra-low density polyethylene is preferably unmodified polyethylene, but in addition to unmodified polyethylene, acid-modified polyethylene and polyethylene other than ultra-low density polyethylene, such as low density polyethylene (LDPE), medium density polyethylene. (MDPE), polyethylene such as high density polyethylene (HDPE), linear low density polyethylene (LLDPE), or these acid-modified polyethylenes may be used in combination.

(D) Aluminum hydroxide The non-halogen flame retardant resin composition of the present invention contains (d) aluminum hydroxide as a flame retardant.
Aluminum hydroxide may or may not be surface treated. Examples of the surface treatment include treatment with a fatty acid or a silane coupling agent. Moreover, you may use together what does not carry out surface treatment. Since aluminum hydroxide is available at a lower price than magnesium hydroxide, the non-halogen flame retardant resin composition of the present invention can be produced at a lower price.
As the aluminum hydroxide that has not been subjected to surface treatment, for example, (trade name, Heidilite H42M, manufactured by Showa Denko KK) can be used as a commercial product. As aluminum hydroxide surface-treated with fatty acids such as stearic acid and oleic acid, the trade name, Hydylite H42S manufactured by Showa Denko Co., Ltd.)), and aluminum hydroxide surface-treated with a silane coupling agent, (Trade name, Heidilite H42STV, Showa Denko Co., Ltd., etc.) can be used.

As the silane coupling agent used for the surface treatment of aluminum hydroxide, vinyltrimethoxysilane, vinyltriethoxysilane, glycidoxypropyltrimethoxysilane, glycidoxypropyltriethoxysilane, glycidoxypropylmethyldimethoxysilane, Mercapto such as methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane, methacryloxypropylmethyldimethoxysilane and other vinyl or epoxy-terminated silane coupling agents, mercaptopropyltrimethoxysilane, mercaptopropyltriethoxysilane, etc. Silane coupling agent having a terminal group, aminopropyltriethoxysilane, aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-amino A crosslinkable silane coupling agent such as a silane coupling agent having an amino group such as propyltripropyltrimethoxysilane and N- (β-aminoethyl) -γ-aminopropyltripropylmethyldimethoxysilane is preferred. Two or more of these silane coupling agents may be used in combination.
Among such crosslinkable silane coupling agents, silane coupling agents having an epoxy group and / or a vinyl group / methacryloxy group at the terminal are more preferable, and these may be used alone or in combination of two or more. May be.

As the aluminum hydroxide surface-treated with the silane coupling agent that can be used in the present invention, an amount of silane coupling agent sufficient for the surface treatment in advance can be appropriately blended with aluminum hydroxide. . Specifically, the amount of the silane coupling agent is preferably 0.2 to 2% by mass with respect to the metal hydrate. The silane coupling agent may be a stock solution or may be diluted with a solvent.
Moreover, aluminum hydroxide etc. which surface-treated using the silane coupling agent for the metal hydrate by which a part of surface was pre-processed previously with the fatty acid, phosphate ester, etc. can also be used.

In the non-halogen flame retardant resin composition of the present invention, the aluminum hydroxide is contained in an amount of 50 to 120 parts by mass with respect to 100 parts by mass of the base resin component.
Here, the base resin component is a mixed resin component of ethylene / propylene rubber, ethylene-vinyl acetate copolymer and ultra-low density polyethylene, which are essential in the present invention.
If the aluminum hydroxide content is too low, sufficient flame retardancy cannot be obtained, and if it is too high, the mechanical strength decreases. The content of aluminum hydroxide is preferably 60 to 100 parts by mass, and more preferably 70 to 90 parts by mass.

  In this invention, you may use together a flame retardant other than aluminum hydroxide, and a flame retardant adjuvant. Examples of such flame retardants and flame retardant aids include phosphorus compounds, red phosphorus, silicone compounds, nitrogen compounds, and zinc compounds.

(E1) Cross-linking agent, (e2) Cross-linking auxiliary The non-halogen flame-retardant insulated wire of the present invention has a coating layer formed using the non-halogen flame-retardant resin composition on the outermost layer on the outer periphery of the conductor. Are cross-linked. As a crosslinking method, radiation crosslinking or chemical crosslinking is appropriately performed. The method is appropriately performed by a conventional method.
The non-halogen flame retardant insulated wire of the present invention is a non-halogen flame retardant resin composition by blending a crosslinking agent, and the composition is extrusion coated directly or indirectly on a conductor and heat-treated, that is, by chemical crosslinking. It is preferable to manufacture.
The temperature of extrusion coating in the case of chemical crosslinking is preferably 70 to 140 ° C., more preferably 80 to 110 ° C., since ethylene / propylene rubber is included as a base resin component and a crosslinking agent is added. is there.

  Preferred examples of the crosslinking agent include organic peroxides. For example, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxide) hexyne, 1,3-bis- (t-butylperoxyisopropyl) benzene, 1,1, -di- Examples thereof include t-butylperoxy-3,3,5-trimethylcyclohexane. The blending amount is preferably 1 to 5 parts by mass, and more preferably 2 to 4 parts by mass with respect to 100 parts by mass of the base resin component. If the amount of the crosslinking agent is too small, crosslinking of the non-halogen flame retardant resin composition becomes insufficient and heat resistance is lowered. When there are too many compounding quantities of a crosslinking agent, a crosslinking density will become high too much and sufficient tensile elongation physical property will not be obtained.

  The non-halogen flame retardant insulated wire of the present invention is excellent in heat resistance because the coating layer formed using the non-halogen flame retardant resin composition is crosslinked. When the coating layer is cross-linked by chemical cross-linking, it is preferable that the non-halogen flame retardant resin composition is extrusion-coated directly or indirectly on the conductor, and then heated at 160 to 200 ° C. for cross-linking.

Examples of the production of the non-halogen flame-retardant insulated wire of the present invention by radiation crosslinking include γ-ray crosslinking in addition to electron beam crosslinking. Of these, electron beam crosslinking is preferred. When performing electron beam cross-linking, the irradiation dose of the electron beam is preferably 1 to 30 Mrad. Polyfunctional compounds such as (meth) acrylate compounds such as polypropylene glycol diacrylate and trimethylolpropane triacrylate, allyl compounds such as triallyl cyanurate, maleimide compounds, and divinyl compounds for efficient crosslinking May be blended as a crosslinking aid. The blending amount of the crosslinking aid is preferably 1 to 10 parts by mass, and more preferably 1 to 6 parts by mass with respect to 100 parts by mass of the base resin component.
The polyfunctional compound used for the cross-linking aid may differ in cross-linking efficiency depending on the number of double bonds per unit mass contained in the polyfunctional monomer, but if the blending amount of the cross-linking aid is too small Further, crosslinking of the non-halogen flame retardant resin composition becomes insufficient, and heat resistance is lowered. If the amount of the crosslinking aid is too large, the crosslinking density becomes too high and sufficient tensile elongation properties cannot be obtained.

(F) Other additives The non-halogen flame retardant resin composition of the present invention includes various additives used in the wire coating layer, for example, fillers such as zinc oxide, reinforcing agents such as carbon and silica, Colorants, aliphatic carboxylic acids or salts thereof, lubricants such as waxes, anti-aging agents, and the like can be appropriately blended within a range that does not impair the object of the present invention.

  In the non-halogen flame-retardant insulated wire of the present invention, the outermost layer on the outer periphery of the conductor is a coating layer made of a resin composition that is highly filled with 50 to 120 parts by mass of aluminum hydroxide with respect to 100 parts by mass of the base resin component. In spite of being formed, it has sufficient flexibility, good compatibility of the mixed resin component, and excellent whitening resistance due to rubbing.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples.

Examples 1 to 10 in Table 1 and Comparative Examples 1 to 10 in Table 2 were melt-kneaded using a Banbury mixer except for the organic peroxide among the components shown in Tables 1 and 2. Thereafter, organic peroxides having the blending amounts shown in Tables 1 and 2 were added to the kneaded product, and the mixture was kneaded with an 8-inch roll set at 40 to 80 ° C. to obtain a non-halogen flame-retardant resin composition. . The obtained non-halogen flame retardant resin composition was molded into a sheet and then press vulcanized at 160 ° C. for 30 minutes to crosslink the non-halogen flame retardant resin composition. Test pieces of the following various tests were prepared from the non-halogen flame retardant resin composition, the following tests were performed, and the performance was evaluated.
However, for Examples 9 and 10 in Table 1 and Comparative Examples 9 and 10 in Table 2, all the components shown in Tables 1 and 2 were added and melt-kneaded using a Banbury mixer to produce a halogen-free flame retardant resin composition. I got a thing. After the obtained non-halogen flame retardant resin composition was formed into a sheet shape, the following various test specimens were prepared and evaluated in the same manner as described above by using a crosslinked product by irradiation with an electron beam at 15 Mrad. .

Here, the various materials described in Tables 1 and 2 are as follows.
In addition, each component in the base resin components [ethylene / propylene rubber (EPDM), ethylene-vinyl acetate copolymer (EVA), low density polyethylene (LDPE)] described in Tables 1 and 2 is in the base resin component. The content of is shown by mass%.

(Materials used)
(1) EPDM (ethylene propylene rubber)
EPDM1 ethylene content 54% by weight, diene content 8.1% by weight
EPDM2 ethylene content 67% by mass, diene content 6.0% by mass
(2) EVA (ethylene-vinyl acetate copolymer)
EVA1 VA content 19% by mass, density 0.94 g / cm ³
EVA2 VA content 33% by mass, density 0.96 g / cm ³
EVA3 VA content 60 wt%, density 1.07 g / cm ³
(3) PE (polyethylene)
VLDPE1 (very low density polyethylene) crystallinity 18%, density 0.870 g / cm ³ , melting temperature 60 ° C.
VLDPE2 (very low density polyethylene) crystallinity 25%, density 0.885 g / cm ³ , melting temperature 77 ° C.
LDPE1 (low density polyethylene) crystallinity 50%, density 0.923 g / cm ³ , melting temperature 111 ° C.

(4) Aluminum Hydrite H42M Showa Denko's product name (5) Reinforcing agent Seast 3 Tokai Carbon Co., Ltd. product name HAF (High Absorption Furnace): High abrasion resistance grade (6) Lubricant Beads stearic acid NOF Corporation Product Name (7) Filler Zinc Oxide Type 2 Mitsui Kinzoku Mining Co., Ltd. Product Name (8) Anti-aging Agent NOCRACK 224 Ouchi Shinsei Chemical Co., Ltd. Product Name (9) Organic Peroxide Park Mill D NOF Product Name (10) Crosslinking aid Ogmont T-200 Shin-Nakamura Chemical Co., Ltd.

(1) Tensile evaluation Tensile strength, elongation, and modulus were measured using a test piece having a thickness of 2 mm in accordance with JIS K 6251 (use of vulcanized rubber tensile test method JIS No. 3 dumbbell).
A tensile strength of 10 MPa or more, a tensile elongation of 300% or more, and a 100% modulus of 5 MPa or less were accepted.

(2) Flame retardance Using a test piece having a thickness of 3 × width of 10 × length of 300 mm, 28. of JIS C 3005 (rubber / plastic insulated wire test method). The test was conducted in accordance with the “inclination test method for flame retardancy”.
Those with a fire extinguishing time of 60 seconds or less after ignition were indicated by ○, those that did not extinguish within 60 seconds were indicated by ×, and ○ was designated as flame retardant.

(3) Heat resistance Using a test piece having a thickness of 2 mm, the sample was heated at 150 ° C. for 96 hours in accordance with JIS K 6257 (Aging test method for vulcanized rubber), and the residual aging rate of elongation at the time of cutting of the test piece was measured. (%) Was measured.
When the residual aging rate was 80% or more, the heat resistance was accepted.

(4) Insulation 6. Using JIS K 6271 (How to determine volume resistivity of vulcanized rubber and thermoplastic rubber) using a test piece having a thickness of 1 mm. The volume resistivity was measured according to the “double ring electrode method”.
The case where the volume resistivity was 1.0 × 10 ¹⁴ (Ω · cm) or more was regarded as acceptable.

For Examples 1 to 8 in Table 1 and Comparative Examples 1 to 8 in Table 2, an electric wire having an outer diameter of φ3.7 mm obtained by extrusion molding the coating layer so that the thickness of the coating layer was 1.0 mm Was steam-crosslinked (under a pressure of 1.5 Mpa of vapor pressure) to produce an insulated wire.
For Examples 9 and 10 in Table 1 and Comparative Examples 9 and 10 in Table 2, the outer diameter φ 3.7 mm obtained by extrusion molding the coating layer so that the thickness of the coating layer was 1.0 mm. The insulated wire was manufactured by irradiating with 15 Mrad with an electron beam and crosslinking.
These insulated wires were evaluated for peelability and rubbing whitening as follows.

(5) Peeling off When stripping the insulated wire with the wire strip used for the end treatment of the wire, the end face has a notch or a knife is used to cut the wire in the circumferential direction. When the insulated wire was stripped, the one that was difficult to strip was rejected.

(6) Friction whitening property A case in which scratches appearing on the surface of the wire when the wire was pulled out in a state where a load of 500 g was pressed against the surface of the insulated wire against a 90 ° metal edge was rejected.

  The obtained results are summarized in Tables 1 and 2 below.

  Here, E content is ethylene component content, D content is diene component content, and VA content is vinyl acetate component content.

From the results of Table 1, all of the resin compositions of Examples 1 to 10 have a tensile strength of 10 MPa or more, a tensile elongation of 300% or more, and a 100% modulus of 5 MPa or less while maintaining the mechanical strength, and the elongation is large. Since it has a small 100% modulus value, it can be seen that it has excellent mechanical properties and flexibility. The flame retardancy is extinguished within 60 seconds after ignition, and the flame retardance is acceptable. Regarding the heat resistance, the residual aging rate at the time of cutting after the heating test was 80% or more, and all passed. Further, all the insulating properties were 1.0 × 10 ¹⁴ Ω · cm or more, which was acceptable. As for the mouth-peeling property and rubbing whitening property, there was no uncut residue, there was no difficulty in stripping with a knife, and there was no noticeable damage on the surface of the electric wire.

On the other hand, from Table 2, each comparative example shows the following.
Although the comparative example 1 has passed the flame retardancy, it contains a large amount of ethylene-vinyl acetate copolymer having a high vinyl acetate content, and a very low density polyethylene is incorporated in a small amount. The insulation was unacceptable, and the peelability and rubbing whitening property were also unacceptable.

  Comparative Example 2 uses an ethylene-vinyl acetate copolymer having a high vinyl acetate content as in Comparative Example 1, although the amount of ultra-low density polyethylene blended is large and the mouth-peeling property and abrasion whitening property are good. Therefore, the tensile strength is small and the insulating property does not pass.

  In Comparative Examples 3 and 4, an ethylene-vinyl acetate copolymer having a vinyl acetate content of 33% by mass was used, but the blending amount was large, and since it did not contain ultra-low density polyethylene, insulation, Mouth peelability and whitening resistance are unacceptable, and 100% modulus is high. Further, in Comparative Example 4, since there are few crosslinking agents, the elongation aging residual ratio is less than 80%, and the heat resistance reaches the acceptable level. There wasn't.

  Comparative Examples 5 and 6 contain not only ultra-low-density polyethylene but also high-density polyethylene with a high degree of crystallinity, so the tensile strength is sufficient, but the 100% modulus is large and the tensile evaluation is at an acceptable level. Did not reach. Although the whitening property was good, the 100% modulus was high, affecting the flexibility, and the peelability did not reach the acceptable level. In both cases, since the amount of aluminum hydroxide is small, flame retardancy was insufficient.

  In Comparative Example 7, the blending amount of ethylene / propylene rubber is large, and the insulating property, the peelability, and the whitening property have passed. However, the blending amount of the ethylene-vinyl acetate copolymer is small, and the flame retardancy is at an acceptable level. Did not reach. Moreover, the tensile strength was insufficient and the heat resistance was also unacceptable.

  In Comparative Examples 8, 9 and 10, ethylene / propylene rubber and ethylene-vinyl acetate copolymer are blended in a certain amount, but low density polyethylene having a high degree of crystallinity as in Comparative Examples 5 and 6 is used. Since it was blended, the 100% modulus was large, the flexibility was inferior, and the peelability did not reach the level. Further, in Comparative Example 10, since the amount of the crosslinking agent was small, the elongation aging residual ratio was less than 80%, and the heat resistance did not reach the level.

1 Conductor 2 Other layer (eg separator)
3 Crosslinked coating layer 4 using non-halogen flame retardant resin composition Other coating layer 5 Internal conductive layer 10 Non-halogen insulated wire 20 Non-halogen insulated wire 30 Non-halogen insulated wire

Claims (9)

  (A) 20 to 40% by mass of ethylene / propylene rubber having an ethylene component content of 50 to 75% by mass, and (b) 30 to 50% of ethylene-vinyl acetate copolymer having a vinyl acetate component of 40% by mass or less. % And (c) 50 to 120 parts by mass of aluminum hydroxide with respect to 100 parts by mass of the base resin component containing 10 to 40% by mass of ultra-low density polyethylene having a crystallinity of 40% or less. Non-halogen flame retardant resin composition.   The non-halogen flame-retardant resin composition according to claim 1, wherein the component (a) is ethylene / propylene / diene rubber.   3. The non-halogen flame retardant resin composition according to claim 1, wherein the content of the diene component in the rubber (a) is 3 to 10% by mass.   The halogen-free flame retardant resin according to any one of claims 1 to 3, wherein the diene component in the rubber (a) is a dicyclopentadiene component or a 5-ethylidene-2-norbornene component. Composition. The non-halogen flame-retardant resin composition according to any one of claims 1 to 4, wherein the density of the ultra-low density polyethylene of the component (c) is 0.91 g / cm ³ or less.   The non-halogen flame retardant according to any one of claims 1 to 5, wherein a melting temperature of the ultra-low density polyethylene of component (c) by a differential scanning calorimeter (DSC) is 30 to 120 ° C. Resin composition.   Furthermore, the non-halogen flame retardant resin composition according to any one of claims 1 to 6, further comprising a crosslinking agent or / and a crosslinking assistant.   A molded article obtained by crosslinking the non-halogen flame retardant resin composition according to any one of claims 1 to 7.   A non-halogen flame retardant having a coating layer formed using the non-halogen flame retardant resin composition according to any one of claims 1 to 7 on the outer periphery of the conductor, and the coating layer being crosslinked. Insulated wires.

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