JP2012124061A - Flame retardant wire/cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a halogen-free flame retardant wire/cable having both excellent flame resistance and excellent mechanical characteristics.SOLUTION: The flame retardant wire/cable has a coating on an outer periphery of a conductor. The coating comprises a halogen-free flame retardant resin composition containing 30 to 90 pts. mass of (C) huntite with an average particle size (D) of 0.3 to 0.7 μm and (D) hydromagnesite with an average particle size (D) of 3.0 to 5.0 μm in total, relative to 100 pts. mass of a base polymer comprising (A) an ethylene-vinyl acetate copolymer and (B) an ethylene-acrylic acid ethyl copolymer, while a mass ratio of (C) huntite and (D) hydromagnesite is 40:60 to 60:40.

Description

  The present invention relates to an electric wire / cable that is halogen-free and excellent in flame retardancy and mechanical properties.

  In recent years, in the field of electric wires and cables, in consideration of the environment, instead of a composition containing polyvinyl chloride (PVC) that generates harmful gases such as hydrogen halide during incineration or a halogen-based flame retardant, polyolefin has been used. 2. Description of the Related Art Electric wires and cables using a halogen-free composition made flame-retardant by adding a metal hydroxide such as aluminum hydroxide or magnesium hydroxide as a material for an insulator or a sheath have been widely used.

  However, in such a halogen-free flame retardant composition, it is difficult to achieve both flame retardancy and mechanical properties (tensile strength, tensile elongation, etc.), and metal hydroxide is used to increase flame retardancy. When blended in a large amount, the mechanical properties deteriorate, and conversely, if the blended amount of the metal hydroxide is decreased in order to obtain good mechanical properties, there is a problem that the flame retardancy becomes insufficient.

  Therefore, various techniques have been proposed to solve such problems. For example, Patent Document 1 discloses an automotive electric wire in which a composition obtained by combining two specific types of polyolefin, two specific types of inorganic flame retardants such as huntite and hydromagnesite, is disclosed. Patent Document 2 discloses an electric wire / cable coated with a composition in which an olefin polymer is mixed with a metal oxide instead of a metal hydroxide and a specific metal salt that releases an incombustible gas during combustion. It is disclosed.

  However, in such a conventional technique, although some improvement is recognized, the effect is not enough, and the electric wire and cable which have sufficient flame retardance and mechanical characteristics are not yet obtained.

Japanese Patent Laid-Open No. 6-200089 JP 2010-1111760 A

  The present invention has been made to solve such problems of the prior art, and an object thereof is to provide a wire / cable that is halogen-free and has both excellent flame retardancy and mechanical characteristics.

The flame-retardant electric wire / cable according to the first aspect of the present invention is based on 100 parts by mass of a base polymer composed of (A) an ethylene / vinyl acetate copolymer and (B) an ethylene / ethyl acrylate copolymer. 30 to 90 parts by weight containing at huntite and (D) average particle diameter _(D 50) the total amount of the hydro magnesite 3.0~5.0μm of C) average particle size _(D 50) 0.3 to 0.7 [mu] m In addition, the outer circumference of the conductor is coated with a halogen-free flame-retardant resin composition having a mass ratio of (C) huntite and (D) hydromagnesite of 40:60 to 60:40.

  According to a second aspect of the present invention, in the flame-retardant electric wire / cable of the first aspect, the mass ratio of the (A) ethylene / vinyl acetate copolymer and the (B) ethylene / ethyl acrylate copolymer is 50: 50-70: 30.

  According to a third aspect of the present invention, in the flame-retardant electric wire / cable of the first aspect or the second aspect, the (A) ethylene / vinyl acetate copolymer and the (B) ethylene / ethyl acrylate copolymer are used. The mass ratio of the coalescence is 55:45 to 65:35.

  According to a fourth aspect of the present invention, in the flame-retardant electric wire / cable according to any one of the first to third aspects, the (C) huntite and the (D ) Hydromagnesite is contained in a total amount of 40 to 60 parts by mass.

  According to a fifth aspect of the present invention, in the flame-retardant electric wire / cable of any one of the first to fourth aspects, the mass ratio of the (C) huntite to the (D) hydromagnesite is 45. : 55-55: 45.

  According to a sixth aspect of the present invention, in the flame-retardant electric wire / cable of any one of the first to fifth aspects, 2 to 5 (E) silicone powder is added to 100 parts by mass of the base polymer. Contains part by mass.

  According to a seventh aspect of the present invention, in the flame-retardant electric wire / cable according to any one of the first to sixth aspects, the coating made of the halogen-free flame-retardant resin composition has a tensile strength of 10 MPa or more. It has strength and tensile elongation of 400% or more.

  According to the flame-retardant electric wire / cable of the present invention, it is halogen-free and can have both excellent flame retardancy and excellent mechanical properties.

It is a cross-sectional view which shows one Embodiment of the flame-retardant electric wire and cable of this invention. It is a cross-sectional view which shows other embodiment of the flame-retardant electric wire and cable of this invention.

  Embodiments of the present invention will be described below.

  First, the halogen-free flame-retardant resin composition used for the flame-retardant electric wire / cable of the present invention will be described.

The halogen-free flame retardant resin composition used in the present invention comprises (A) an average particle size of (A) an ethylene / vinyl acetate copolymer and (B) an ethylene / ethyl acrylate copolymer. It contains huntite having a diameter (D ₅₀ ) of 0.3 to 0.7 μm and (D) hydromagnesite having an average particle diameter (D ₅₀ ) of 3.0 to 5.0 μm.

The ethylene / vinyl acetate copolymer of component (A) is not particularly limited, but the vinyl acetate (VA) content is 32 to 34% by mass and the density (JIS K 7112) is 0.950 to 0.00. 970 g / cm ³ , MFR (JIS K 7210; 230 ° C., 2.16 kg load) is 0.2 to 0.4 g / 10 min, Shore A hardness (JIS K 7215) is 66 to 70, melting point (JIS K 7121) ) Is preferably from 59 to 63 ° C. Specific examples of commercially available products having such physical properties include EVAFLEX EV150 (trade name, manufactured by Mitsui DuPont Polychemical Co., Ltd.).

  The ethylene / ethyl acrylate copolymer of the component (B) is not particularly limited, but the ethyl acrylate (EA) content is 14 to 16% by mass, MFR (JIS K 6922-2; 230 ° C., 2.16 kg load) is preferably 0.7 to 0.9 g / 10 min and melting point (JIS K 7121) is preferably 80 to 120 ° C. Specific examples of commercially available products having such physical properties include Lexpearl EEA A1150 (trade name, manufactured by Nippon Polyethylene Co., Ltd.).

  In the base polymer of the halogen-free flame-retardant resin composition used in the present invention, the blending ratio (A) :( B) of the component (A) and the component (B) is from the viewpoint of mechanical properties and processability. The mass ratio is preferably 50:50 to 70:30. More preferably, it is 55: 45-65: 35, More preferably, it is 58: 42-63: 37.

Both (C) component huntite and (D) component hydromagnesite are blended as flame retardants. Huntite is a white crystal represented by the composition formula Mg ₃ Ca (CO ₃ ) ₄ , and hydromagnesite is composed of the composition formula Mg ₄ (CO ₃ ) ₃ (OH) ₂ .H ₂ O or Mg ₄ (CO ₃ ) A white crystal represented by ₃ (OH) ₂ .3H ₂ O. While metal hydroxides such as magnesium hydroxide, which are widely used as flame retardants, exhibit a flame retardant effect mainly due to endothermic reaction due to dehydration, Huntite is used in the event of a fire as shown below. As a result of being decomposed by heat and releasing carbon dioxide (CO ₂ ), oxygen is blocked or diluted to exhibit a flame retardant effect. Hydromagnesite exhibits a flame retardant effect due to the combined effect of both, ie, the effect of blocking or diluting oxygen by releasing carbon dioxide (CO ₂ ) and the endothermic reaction by dehydration.
Mg ₃ Ca (CO ₃ ) ₄ → 3MgO + CaO + 4CO ₂
Mg ₄ (CO ₃ ) ₃ (OH) ₂ .3H ₂ O → 4MgO + 3CO ₂ + 4H ₂ O

The huntite of the component (C) used in the present invention has an average particle size (D ₅₀ ) of 0.3 to 0.7 μm, preferably 0.4 to 0.6 μm. When the average particle diameter (D ₅₀ ) of huntite is less than 0.3 μm, the mechanical properties are lowered, and when it exceeds 0.7 μm, the flame retardancy is lowered. Further, the hydromagnesite (D) component has an average particle diameter (D ₅₀ ) of 3.0 to 5.0 μm, preferably 2.0 to 4.0 μm. When the average particle size (D ₅₀ ) of hydromagnesite is less than 3.0 μm, the mechanical properties are lowered, and when it exceeds 5.0 μm, the flame retardancy is lowered.

In addition, the average particle diameter (D ₅₀ ) of huntite and hydromagnesite in the present specification is a cumulative curve with the total volume of the powder group obtained by measurement with a laser diffraction particle size distribution measuring device as 100%, The particle diameter at the point where the cumulative curve is 50%.

  The mixing ratio (C) :( D) of these (C) component and (D) component is 40: 60-60: 40 by mass ratio. When the proportion of the component (C) is less than the above range, the flame retardancy is lowered, and when the proportion of the component (C) exceeds the above range, the workability is lowered. The blending ratio (C) :( D) is preferably 45:55 to 55:45, and more preferably 47:53 to 53:47.

Naturally, huntite and hydromagnesite are produced as a mixture thereof. Such a naturally produced mixture is commercially available, for example, from MINELCO under the trade name ULTRACARB. In the present invention, such a naturally produced mixture can also be used. Incidentally, the ultra curve is produced by crushing the raw stone, removing impurities such as magnesite, and then classifying, and for example, the mass ratio of huntite and hydromagnesite is 50:50, the huntite average particle diameter ( D ₅₀ ) 0.5 μm, hydromagnesite average particle size (D ₅₀ ) 4.0 μm (trade name ULTRACARB LH2), and the like.

  The (C) component huntite and the (D) component hydromagnesite may be surface-treated with higher fatty acids such as stearic acid, silane coupling agents, molybdates, and the like. By using such a surface-treated powder, the dispersibility when kneading with the polymer component can be enhanced.

  In the present invention, the compounding amount of the component (C) huntite and the component (D) hydromagnesite is 30 to 90 parts by mass in total with respect to 100 parts by mass of the total amount of the base polymer component described above. Preferably it is 40-60 mass parts, More preferably, it is 45-55 mass parts. If the blending amount is less than 30 parts by mass, the flame retardancy is lowered. Conversely, if it exceeds 90 parts by mass, huntite or hydromagnesite may bloom on the surface.

  The halogen-free flame retardant resin composition used in the present invention can be blended with (E) silicone powder in order to further improve flame retardancy and mechanical properties. This (E) silicone powder is known as a flame retardant aid. In the present invention, it is preferable to use those having a particle size of 10 to 200 μm from the viewpoint of improving flame retardancy. Specific examples of commercially available products suitable as the component (E) include DC4-7081 (trade name, manufactured by Toray Dow Corning Co., Ltd .; particle diameter: 10 to 200 μm).

  The blending amount of the silicone powder of the component (E) is preferably 2 to 5 parts by mass with respect to 100 parts by mass of the total amount of the base polymer component described above. If the blending amount is less than 2 parts by mass, the effect of addition may not be sufficiently obtained, and if it exceeds 5 parts by mass, the silicone powder may bloom on the surface.

  In addition, the halogen-free flame retardant resin composition used in the present invention includes other non-halogen flame retardants and flame retardant aids other than the components (C) to (E) described above. It can mix | blend in the range which does not inhibit. Examples of such non-halogen flame retardants include metal hydroxides such as aluminum hydroxide, zirconium hydroxide, calcium hydroxide and barium hydroxide, nitrogen flame retardants such as guanidine and melamine, ammonium phosphate and red phosphorus. Examples thereof include phosphorus-based flame retardants, phosphorus-nitrogen-based flame retardants, boric acid compounds such as zinc borate, and calcium carbonate.

  Furthermore, additives such as antioxidants, ultraviolet absorbers, heat aging inhibitors, fillers, processing aids, lubricants, colorants and the like can be blended as needed, as long as the effects of the present invention are not impaired. it can.

  Antioxidants and heat aging inhibitors include pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,6-di-t-butyl-p-cresol, 2 Phenolic antioxidants such as -t-butyl-4,6-dimethylphenol and 2,6-di-t-butyl-4-ethylphenol, distearyl-pentaerythritol-diphosphite, tetrakis (2,4-di- phosphorous antioxidants such as t-butylphenyl) -4,4'-biphenylene-di-phosphite, bis (2,4-di-t-butylphenyl) pentaerythritol-diphosphite, dilauryl-3,3'- Thiodipropionate, 4,4'-thiobis- (6-tert-butyl-3-methylphenol), dimyristyl-3, '- thiodipropionate, and the like sulfur-based antioxidant such as distearyl-3,3'-thiodipropionate.

  Examples of the ultraviolet absorber include 2- (2′-hydroxy-4′-n-octoxyphenyl) bezotriazole, 2,4-di-t-butylphenyl-3,5-di-t-butyl-4- Examples thereof include hydroxybenzoate.

  Examples of the filler include fused silica, crystalline silica, alumina, zirconia, talc, clay, mica, calcium carbonate, titanium white, bengara, silicon carbide, boron nitride, silicon nitride, and aluminum nitride.

  Examples of processing aids include ricinoleic acid, stearic acid, palmitic acid, lauric acid, and salts or esters thereof.

  Examples of the lubricant include hydrocarbons, fatty acids, fatty acid amides, esters, and alcohols.

  Each of the above additives may be used alone or in combination of two or more.

  The halogen-free flame-retardant resin composition used in the present invention includes (A) an ethylene / vinyl acetate copolymer, (B) an ethylene / ethyl acrylate copolymer, (C) huntite, (D ) Hydromagnesite, (E) Silicone powder, and various components described above blended as necessary using a conventional kneader such as a Banbury mixer, tumbler, pressure kneader, kneading extruder, mixing roller, etc. It can be easily manufactured by mixing them.

  The halogen-free flame retardant resin composition can crosslink the polymer component after coating. The cross-linking method is not particularly limited, and any cross-linking method such as a chemical cross-linking method in which a cross-linking agent is previously added to the flame retardant resin composition and cross-linking after coating, or a cross-linking method by irradiation with radiation such as an electron beam is used. The method can be used. Examples of the crosslinking agent used in the chemical crosslinking method include dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane, 2,5- Dimethyl-2,5-di- (tert-butylperoxy) hexyne-3, 1,3-bis (tert-butylperoxyisopropyl) benzene, 1,1-bis (tert-butylperoxy) -3,3 5-trimethylcyclohexane, n-butyl-4,4-bis (tert-butylperoxy) valerate, benzoyl oxide, 2,4-dichlorobenzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxyisopropyl carbonate, Diacetyl peroxide, lauroyl peroxide Such as tert- butyl cumyl peroxide and the like.

  The degree of crosslinking is preferably 50% or more, more preferably 65% or more in terms of gel fraction. If the gel fraction is less than 50%, the mechanical properties cannot be sufficiently improved. This gel fraction is measured based on the crosslinking degree test method specified in JIS C 3005.

  The flame-retardant electric wire / cable of the present invention is produced by extrusion-coating the halogen-free flame-retardant resin composition described above on a conductor directly or through another coating, and cross-linking as necessary. The material of the conductor, the outer diameter, the presence or absence of twisting, etc. are not particularly limited, and are appropriately selected depending on the application.

  FIG. 1 is a cross-sectional view showing a flame-retardant electric wire / cable according to an embodiment of the present invention.

  As shown in FIG. 1, the flame-retardant electric wire / cable 10 of the present embodiment shows a conductor 11 made of one or more tin-plated annealed copper wires or the like. On this conductor 11, an insulator 12 made of cross-linked polyethylene is provided by a conventional method. A sheath 13 is further formed on the insulator 12 by extruding the halogen-free flame retardant resin composition described above.

It is preferable that the flame-retardant electric wire / cable 10 of this embodiment is comprised so that the following requirements may be satisfied.
(1) As a whole electric wire, it has flame retardancy that passes the JIS C 3005 60 degree inclined combustion test.
(2) The tensile strength and tensile elongation (measured in accordance with JIS C 3005) of the sheath 12 are 10 MPa or more and 400% or more, respectively.

  In the flame-retardant electric wire / cable 10 of the present embodiment, (A) an ethylene / vinyl acetate copolymer and (B) an ethylene / ethyl acrylate copolymer are mixed at a specific ratio to form a base polymer, The base polymer is coated with a halogen-free flame-retardant resin in which (C) huntite and (D) hydromagnesite having a specific average particle size and silicone powder having a specific particle size are blended in a specific ratio. I have. This coating can have good flame retardancy despite a small amount of flame retardant used compared to a coating made of a composition using a conventional metal hydroxide. For this reason, it can have the flame-retardant property and mechanical characteristics which were excellent in halogen-free.

  FIG. 2 is a cross-sectional view showing a flame-retardant electric wire / cable according to another embodiment of the present invention.

  In the flame-retardant electric wire / cable 20 of the present embodiment, three insulated wire cores 21 covered with an insulator 12 made of crosslinked polyethylene are twisted together with an intervening 14 on a conductor 11, and a press-wound tape 15 is wound around the outer periphery thereof. The sheath 13 is covered therewith. The sheath 13 is formed by extrusion coating the halogen-free flame retardant resin composition described above.

  Since the flame-retardant electric wire / cable 20 of the present embodiment also includes the sheath 13 made of the halogen-free flame-retardant resin composition described above, similarly to the flame-retardant electric wire / cable 10 of the first embodiment, it is halogen-free. It has both excellent flame retardancy and mechanical properties.

  The flame retardant electric wire / cable 20 is also preferably configured to satisfy the requirements (1) and (2).

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples at all. The components used in Examples and Comparative Examples are as follows.

EVA (ethylene / vinyl acetate copolymer):
Product name Evaflex EV150 manufactured by Mitsui DuPont Polychemical Co., Ltd .;
Density = 0.960 g / mm ² , MFR = 3.0 g / min, VA content = 33% by mass
Shore A hardness = 68, melting point = 61 ° C.
EEA (ethylene / ethyl acrylate copolymer):
Product name manufactured by Nippon Polyethylene Co., Ltd. Lexpearl EEA A1150;
MFR = 0.8 g / min, EA content = 15% by mass,
Hardness (durometer D) = 41, tensile modulus = 46 MPa,
Flexural modulus = 54 MPa, melting point = 100 ° C.
Huntite / hydromagnesite:
Product name ULTRACARB LH2 made by MINELCO
Magnesium hydroxide:
Product name Made by Kamishima Chemical Co., Ltd. Magseeds ST
Silicone powder:
Product name DC4-7081 manufactured by Toray Dow Corning
Antioxidant:
Product name IRGANOX 1010 manufactured by BASF
Lubricant: Magnesium stearate

Example 1
15 parts by mass of EVA, 85 parts by mass of EEA, 35 parts by mass of huntite / hydromagnesite, 3 parts by mass of silicone powder, 0.5 parts by mass of antioxidant, and 1 part by mass of lubricant are uniformly kneaded with a mixing roll and flame retardant resin A composition was obtained.

Next, a 1.2 mm thick insulator made of crosslinked polyethylene was coated on a copper stranded wire conductor having a cross-sectional area of 38 mm ^{2 by} a conventional method, and then the flame retardant resin composition was extrusion coated to a thickness of 1.5 mm thereon. A flame-retardant electric wire / cable having an outer diameter of about 12.5 mm was manufactured.

(Examples 2-7, Comparative Examples 1-5)
A flame retardant resin composition was prepared in the same manner as in Example 1 except that the composition of the flame retardant resin composition was changed as shown in Table 1. In addition, flame retardant properties were obtained using these compositions. Electric wires and cables were manufactured.

Various characteristics of the flame retardant resin compositions and the flame retardant electric wires / cables obtained in the above Examples and Comparative Examples were evaluated by the following methods.
[Tensile strength and tensile elongation]
A test sheet made of a flame-retardant resin composition was prepared separately from the cable, and a tensile test (tensile speed: 200 mm / min) based on JIS C 3005 was performed and measured.
[Oxygen index]
A test sheet made of a flame-retardant resin composition was prepared separately from the cable, and measured according to JIS K7201-2.
[Flame retardance]
A cable sample cut from a flame-retardant wire / cable is subjected to a 60-degree inclined combustion test specified in JIS C 3005. If the fire extinguishes spontaneously within 60 seconds, it passes, and if it exceeds 60 seconds, it fails. "

  These results are shown in Table 1.

  As is clear from Table 1, Examples 1 to 7 all had good results in tensile strength, tensile elongation, oxygen index, and flame retardancy. Further, by setting the mass ratio of EVA (ethylene / vinyl acetate copolymer) and EEA (ethylene / ethyl acrylate copolymer) to 50:50 to 70:30, the tensile strength and tensile elongation are further improved. Results were obtained (Examples 3-5). Furthermore, EVA (ethylene / vinyl acetate copolymer) and EEA (ethylene / ethyl acrylate copolymer) mass ratio is 55:45 to 65:35, and the total amount of huntite and hydromagnesite is 40 to 60 parts by mass. As a result, better results were obtained in tensile strength, tensile elongation, and oxygen index.

  DESCRIPTION OF SYMBOLS 10, 20 ... Flame-retardant electric wire and cable, 11 ... Conductor, 12 ... Insulator, 13 ... Sheath, 14 ... Interposition, 15 ... Holding tape, 21 ... Insulated wire core.

Claims (7)

(C) with respect to 100 parts by mass of a base polymer composed of ethylene / vinyl acetate copolymer and (B) ethylene / ethyl acrylate copolymer, (C) average particle diameter (D ₅₀ ) of 0.3 to 0.7 μm 30 to 90 parts by mass of a total amount of huntite and (D) hydromagnesite having an average particle diameter (D ₅₀ ) of 3.0 to 5.0 μm, and (C) huntite and (D) hydromagnesite A flame-retardant electric wire / cable characterized by covering a conductor outer periphery with a halogen-free flame-retardant resin composition having a mass ratio of 40:60 to 60:40.   2. The flame retardancy according to claim 1, wherein the (A) ethylene / vinyl acetate copolymer and the (B) ethylene / ethyl acrylate copolymer have a mass ratio of 50:50 to 70:30. Electric wire / cable.   3. The difficulty according to claim 1, wherein a mass ratio of the (A) ethylene / vinyl acetate copolymer and the (B) ethylene / ethyl acrylate copolymer is 55:45 to 65:35. Flammable wires and cables.   The total amount of the (C) huntite and the (D) hydromagnesite is 40 to 60 parts by mass with respect to 100 parts by mass of the base polymer. Flame retardant wire / cable.   5. The flame-retardant electric wire / cable according to claim 1, wherein a mass ratio of the (C) huntite and the (D) hydromagnesite is 45:55 to 55:45.   The flame-retardant electric wire / cable according to any one of claims 1 to 5, wherein 2 to 5 parts by mass of (E) silicone powder is contained with respect to 100 parts by mass of the base polymer.   The flame-retardant electric wire according to any one of claims 1 to 6, wherein the coating comprising the halogen-free flame-retardant resin composition has a tensile strength of 10 MPa or more and a tensile elongation of 400% or more. ·cable.

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