JP6542058B2 - Flame retardant resin composition, cable using the same, and optical fiber cable - Google Patents

Description

  The present invention relates to a flame retardant resin composition, and a cable and an optical fiber cable using the same.

  Polyvinyl chloride resin (PVC) is widely used as a resin used for coating of electric wires and the like. While polyvinyl chloride resin is excellent in processability and has excellent properties such as chemical resistance and flame retardancy, it has a disadvantage of generating toxic gas at the time of combustion.

  On the other hand, a flame retardant resin composition is developed by using a chemically stable and easily processable polyolefin resin as a resin material for coating of electric wires etc., and adding a non-halogen flame retardant thereto. There is. For example, Patent Document 1 discloses a flame-retardant resin composition containing a polyolefin resin, calcium carbonate particles, a silicone-based compound, and a carboxylic acid metal salt.

JP-A-9-169918

  The flame-retardant resin composition of Patent Document 1 ensures excellent mechanical properties and flame retardancy. However, the flame retardant resin composition of Patent Document 1 can not be said to have sufficient properties for use as a cable jacket. In particular, the hardness to withstand trauma and impact, the tearability that can easily tear the outer coating for end processing, and the low-temperature embrittlement property that suppresses the formation of cracks in the outer coating at low temperatures were not sufficient. .

  The present invention has been made in view of the above-mentioned circumstances, and is a flame-retardant resin composition capable of securing excellent mechanical properties and flame retardancy while securing high hardness, easy tearability and low temperature embrittlement properties, And it aims at providing a cable using the same and an optical fiber cable.

  The present inventors conducted various studies in order to solve the above problems, and found that the above problems can be solved by combining the base resin with not only the polyolefin resin but also the elastomer and the acid-modified resin. Thus, the present inventors have completed the present invention.

  That is, the present invention comprises 25% by mass to 70% by mass of high density polyethylene, 10% by mass to 55% by mass of linear low density polyethylene, 10% by mass to 25% by mass of polypropylene elastomer, and acid-modified polyolefin compound 5 Calcium carbonate particles blended in a proportion of 30 parts by weight or more and 50 parts by weight or less and 100 parts by weight or less of a base resin in a proportion of 1 part by weight or more and 10 parts by weight or less And a fatty acid-containing compound blended in a proportion of 2 parts by mass or more and 20 parts by mass or less.

  According to the flame retardant resin composition of the present invention, excellent mechanical properties and flame retardancy can be secured while securing high hardness, easy tearability and low temperature embrittlement properties.

  In the flame-retardant resin composition of the present invention, the present inventors have high hardness, easy tearability, low temperature embrittlement characteristics while ensuring excellent mechanical properties and flame retardancy. It is guessed as follows.

  That is, by making high density polyethylene into the above ratio in the base resin, the flame retardant resin composition can be made high in hardness and excellent in impact resistance and the like. However, high-density polyethylene has a high degree of crystallinity, and the compatibility with the calcium carbonate particles of the base resin is reduced, so that the low temperature embrittlement characteristics are deteriorated. Therefore, the crystallinity of the base resin can be lowered by setting the linear low density polyethylene and the acid-modified polyolefin compound in the above ratio in the base resin, so the compatibility with calcium carbonate particles is improved, and the low temperature brittleness is achieved. Characteristics can be improved.

  Further, by setting the polypropylene-based elastomer to the above-mentioned ratio in the base resin, the interface between the polypropylene-based elastomer and the high density polyethylene becomes the starting point when the tearing occurs, and the tearability can be improved. However, since the polypropylene-based elastomer is inferior in low temperature embrittlement property, the low temperature embrittlement property of the base resin is deteriorated. Therefore, the low temperature embrittlement characteristics can be improved by setting the linear low density polyethylene and the acid-modified polyolefin compound in the above ratio in the base resin.

  Furthermore, calcium carbonate particles act as a flame retardant by being contained in the base resin in the ratio described above, and also serve as a starting point when the interface between calcium carbonate particles and high density polyethylene tears, thereby improving the ease of tearing. be able to.

Further, the flame-retardant resin composition of the present invention, the high-density polyethylene is preferably density of 945 kg / ^{m 3} or more 970 kg / ^{m 3} or less.

  In this case, higher hardness can be obtained as compared to the case where the density of high density polyethylene is out of the above range.

In the flame-retardant resin composition of the present invention, the linear low density polyethylene preferably has a density of 900 kg / m ^{3 to} 940 kg / m ³ .

  In this case, better flame retardancy can be obtained as compared to the case where the density of the linear low density polyethylene is out of the above range.

  The present invention is a cable comprising an insulated wire having a conductor and an insulating layer covering the conductor, wherein the insulating layer is composed of the flame retardant resin composition.

  The present invention is a cable including a conductor, an insulating layer covering the conductor, and a sheath covering the insulating layer, wherein at least one of the insulating layer and the sheath is made of the flame retardant resin composition. Cable.

  The present invention is an optical fiber cable including an optical fiber and a sheath that covers the optical fiber, wherein the sheath is made of the flame retardant resin composition.

  According to the present invention, a flame retardant resin composition capable of securing excellent mechanical properties and flame retardance while securing high hardness, easy tearability and low temperature embrittlement characteristics, a cable using the same, and an optical fiber A cable is provided.

FIG. 1 is a partial side view showing an embodiment of a cable of the present invention. It is sectional drawing along the II-II line of FIG. 1 is a cross-sectional view showing an embodiment of an optical fiber of the present invention. It is sectional drawing which shows the optical fiber sample for easy tearability measurement.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 3.

[cable]
FIG. 1 is a partial side view showing an embodiment of a cable according to the present invention, and FIG. 2 is a cross-sectional view taken along the line II-II of FIG. As shown in FIGS. 1 and 2, the cable 10 includes one insulated wire 4 and a sheath 3 that covers the one insulated wire 4. And the insulated wire 4 has the internal conductor 1 and the insulating layer 2 which coats the internal conductor 1.

  Here, the insulating layer 2 and the sheath 3 are composed of the flame retardant resin composition of the present invention, and the flame retardant resin composition is a high density polyethylene of 25% by mass to 70% by mass, a linear low 30 parts by mass with respect to 100 parts by mass of a base resin containing 10% by mass to 55% by mass of density polyethylene, 10% by mass to 25% by mass of a polypropylene-based elastomer, and 5% by mass to 20% by mass of an acid-modified polyolefin compound Calcium carbonate particles blended in a proportion of 50 parts by mass or less, silicone based compounds blended in a proportion of 1 part by mass to 10 parts by mass, and fatty acids blended in a proportion of 2 parts by mass to 20 parts by mass Containing compounds.

[Method of manufacturing cable]
Next, a method of manufacturing the above-described cable 10 will be described.

(conductor)
First, the internal conductor 1 is prepared. The internal conductor 1 may be configured by only one strand or may be configured by bundling a plurality of strands. Further, the inner conductor 1 is not particularly limited as to the diameter of the conductor, the material of the conductor, and the like, and can be appropriately determined according to the application.

(Flame retardant resin composition)
Next, the inner conductor 1 is coated with the flame retardant resin composition of the present invention. Specifically, the above-mentioned high density polyethylene, linear low density polyethylene, polypropylene-based elastomer, acid-modified polyolefin compound, calcium carbonate particles, silicone-based compound, fatty acid-containing compound and the like are melt-kneaded using an extruder or the like. The flame retardant resin composition of the present invention is obtained. Then, the flame retardant resin composition of the present invention is extruded into a tube shape from an extruder, and the insulating layer 2 is formed by continuously covering the inner conductor 1. Thus, the insulated wire 4 is obtained. In melt-kneading, from the viewpoint of improving the dispersibility of the silicone compound, a part of the base resin and the silicone compound are kneaded, and the obtained master batch (MB) is used as the remaining base resin, calcium carbonate. You may knead | mix with a particle | grain, a fatty acid containing compound, etc.

(sheath)
Finally, one insulated wire 4 obtained as described above is prepared. Then, the flame retardant resin composition of the present invention is extruded into a tube from the extruder, and the sheath 3 is formed by continuously covering the insulated wire 4. The sheath 3 protects the insulating layer 2 from physical or chemical damage.

  The cable 10 is obtained as described above.

  The present invention is not limited to the embodiments described above. For example, although the cable 10 has one insulated wire 4 in the above-mentioned embodiment, it is not limited in particular, and two or more insulated wires 4 may be provided inside the sheath 3.

  Moreover, in the above-mentioned embodiment, although the insulating layer 2 and the sheath 3 of the insulated wire 4 are comprised with the flame retardant resin composition of this invention, one side of the insulating layer 2 or the sheath 3 is comprised with another resin composition. And the other may be comprised of the flame retardant resin composition described above.

  The flame retardant resin composition of the present invention will be further described in detail.

(High density polyethylene)
The high density polyethylene is, as described above, in the proportion of 25% by mass to 70% by mass in the base resin. If the proportion of high density polyethylene is less than 25% by mass, the hardness of the flame retardant resin composition is significantly reduced. If the proportion is more than 70% by mass, the low temperature embrittlement characteristics are significantly reduced.

Incidentally, high-density polyethylene is preferably density of 945 kg / ^{m 3} or more 970 kg / ^{m 3} or less. In this case, higher hardness can be obtained as compared to the case where the density of high density polyethylene is out of the above range.

(Linear low density polyethylene)
The linear low density polyethylene is preferably a linear polyethylene obtained by copolymerizing ethylene and an α-olefin. It does not specifically limit as an alpha-olefin used for linear low density polyethylene, It can select suitably and can use. For example, propylene, butene-1, hexene-1, octene-1, 4-methyl-1-pentene and the like can be mentioned.

  In addition, a known method may be used for the synthesis of linear low density polyethylene, and examples thereof include a method of copolymerizing ethylene and an α-olefin using a metallocene catalyst.

  As described above, linear low density polyethylene has a proportion of 10% by mass or more and 55% by mass or less in the base resin. When the proportion of the linear low density polyethylene is less than 10% by mass, the low temperature embrittlement characteristics of the flame retardant resin composition are significantly reduced. If the proportion is more than 55% by mass, the hardness is significantly reduced.

The linear low density polyethylene preferably has a density of 900 kg / m ³ or more and 940 kg / m ³ or less. In this case, better flame retardancy can be obtained as compared to the case where the density of the linear low density polyethylene is out of the above range.

(Polypropylene elastomer)
The polypropylene-based elastomer is not particularly limited, and can be appropriately selected and used. For example, a copolymer obtained by copolymerizing an α-olefin component such as ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene and the like to propylene is mentioned.

  The polypropylene-based elastomer has a proportion of 10% by mass or more and 25% by mass or less in the base resin as described above. When the proportion of the polypropylene-based elastomer is less than 10% by mass, the tearability of the flame retardant resin composition is significantly reduced. If the proportion is more than 25% by mass, the hardness is significantly reduced. Furthermore, as for the compounding ratio of a polypropylene-type elastomer, 20 mass% or less is preferable. In this case, the hardness can be improved.

(Acid-modified polyolefin compound)
The acid-modified polyolefin compound is not particularly limited, and can be appropriately selected and used. Examples thereof include carboxylic acid or carboxylic acid anhydrides such as maleic anhydride, acrylic acid and methacrylic acid, or unsaturated organic acids such as these esters and their partial esters with polyolefins and the like. Specific examples of the acid-modified polyolefin compound include maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, maleic anhydride-modified ethylene-α-olefin copolymer, maleic anhydride-modified styrene elastomer, maleic anhydride-modified ethylene-propylene copolymer Polymer etc. are mentioned. Among these, maleic anhydride-modified ethylene-α-olefin copolymers are particularly preferable because they exhibit excellent effects in improving low-temperature embrittlement characteristics.

  As described above, the acid-modified polyolefin compound has a ratio of 5% by mass or more and 20% by mass or less in the base resin. When the blending ratio of the acid-modified polyolefin compound is less than 5% by mass, the low temperature embrittlement property of the flame retardant resin composition is lowered. In addition, when the blending ratio is more than 20% by mass, the hardness is significantly reduced.

  Moreover, as a base resin, in addition to high density polyethylene, linear low density polyethylene, a polypropylene-based elastomer, and an acid-modified polyolefin compound, other resins may be contained, and as such other resins, Ethylene-vinyl acetate copolymer resin (EVA), ethylene-ethyl acrylate copolymer (EEA), polyethylene (PE), etc. are mentioned. The proportion of these other resins is preferably 10% by mass or less in the base resin.

(Calcium carbonate particles)
The calcium carbonate particles may be either ground calcium carbonate or light calcium carbonate, but ground calcium carbonate is preferred because it is easily available and inexpensive. The average particle size of the calcium carbonate particles is preferably 0.7 μm or more, more preferably 1.0 μm or more, and still more preferably 1.5 μm or more. If the average particle size of the calcium carbonate particles is too small, the flame retardancy may be reduced. Also, if the average particle size of the calcium carbonate particles is too large, the elongation may decrease, so the upper limit of the average particle size of the calcium carbonate particles is preferably 3.6 μm or less, more preferably 2. It is 2 μm or less.

In the present invention, “average particle diameter” means the area S of a two-dimensional image when a plurality of calcium carbonate particles are observed by SEM, and these areas S are considered to be equal to the area of a circle, respectively. From these areas, the following formula:
R = 2 × (S / π) 1/2
We say the mean value of R calculated each based on.

  The calcium carbonate particles are blended in an amount of 30 parts by mass to 50 parts by mass with respect to 100 parts by mass of the base resin as described above. If the content of the calcium carbonate particles is less than 30 parts by mass, the tearability and flame retardancy of the flame retardant resin composition are significantly reduced. In addition, when the blending ratio is larger than 50 parts by mass, the mechanical properties are significantly reduced.

(Silicone compounds)
The silicone compound functions as a flame retardant auxiliary, and includes polyorganosiloxane and the like. Here, the polyorganosiloxane has a siloxane bond as a main chain and an organic group in a side chain, and examples of the organic group include a methyl group, a vinyl group, an ethyl group, a propyl group and a phenyl group. Specifically, as polyorganosiloxane, for example, dimethylpolysiloxane, methylethylpolysiloxane, methyloctylpolysiloxane, methylvinylpolysiloxane, methylphenylpolysiloxane, methyl (3,3,3-trifluoropropyl) polysiloxane and the like Can be mentioned. Polyorganosiloxanes include silicone powders, silicone gums and silicone resins. Among them, silicone gum is preferred. In this case, bleed out hardly occurs.

  As described above, the silicone-based compound is blended in a ratio of 1 part by mass to 10 parts by mass with respect to 100 parts by mass of the base resin. When the ratio of the silicone-based compound to 100 parts by mass of the base resin is less than 1 part by mass, the flame retardancy is significantly reduced. Moreover, when the compounding ratio of the silicone type compound with respect to 100 mass parts of base resin is larger than 10 mass parts, the bleed-out of the silicone type compound at the time of extrusion processing of a flame retardant resin composition can not fully be suppressed.

  The silicone-based compound is preferably blended in a ratio of 1 part by mass to 3 parts by mass with respect to 100 parts by mass of the base resin. In this case, it is possible to obtain a more excellent hardness as compared to the case where the blending ratio of the silicone-based compound with respect to 100 parts by mass of the base resin is out of the above range.

  The silicone-based compound may be previously attached to the surface of the calcium carbonate particles. Under the present circumstances, it is preferable that the whole of each calcium carbonate particle contained in a flame retardant resin composition is coat | covered with a silicone type compound. In this case, since calcium carbonate particles can be easily dispersed in the polyolefin resin, the uniformity of the characteristics in the flame retardant resin composition is further improved. Moreover, the bleed out of the silicone type compound at the time of extrusion processing of a flame retardant resin composition can be suppressed more sufficiently.

  As a method of attaching a silicone type compound to the surface of calcium carbonate particles, for example, after adding and mixing a silicone type compound to calcium carbonate particles and obtaining a mixture, this mixture is 10-40 minutes at 40-75 ° C. The dried and dried mixture can be obtained by grinding with a Henschel mixer, an atomizer or the like.

(Fatty acid-containing compounds)
The fatty acid-containing compound functions as a flame retardant auxiliary. The fatty acid-containing compound is a fatty acid or a metal salt thereof. Here, as the fatty acid, for example, a fatty acid having 12 to 28 carbon atoms is used. Such fatty acids include, for example, lauric acid, myristic acid, palmitic acid, stearic acid, tubercurostearic acid, oleic acid, linoleic acid, arachidonic acid, behenic acid and montanic acid. Among them, as the fatty acid, stearic acid or tuberculostearic acid is preferable, and stearic acid is particularly preferable. In this case, better flame retardancy can be obtained as compared to the case of using a fatty acid other than stearic acid or tuberculostearic acid.

  Examples of metals constituting metal salts of fatty acids include magnesium, calcium, zinc and lead. As metal salts of fatty acids, magnesium stearate or calcium stearate is preferred. In this case, better flame retardancy can be obtained as compared to the case where the fatty acid-containing compound is neither magnesium stearate nor calcium stearate.

  The fatty acid-containing compound is blended at a ratio of 2 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the base resin as described above. When the proportion of the fatty acid-containing compound is less than 2 parts by mass, the flame retardancy is significantly reduced. Moreover, when the compounding ratio of a fatty acid containing compound is larger than 20 mass parts, the bleed-out of the fatty acid containing compound at the time of extrusion processing of a flame retardant resin composition can not fully be suppressed.

  The fatty acid-containing compound is preferably blended in a proportion of 5 parts by mass or less. In this case, better low temperature embrittlement characteristics can be obtained as compared to the case where the proportion of the fatty acid-containing compound is greater than 5 parts by mass.

  The flame retardant resin composition of the present invention may further contain a filler such as an antioxidant, an ultraviolet light deterioration inhibitor, a processing aid, a color pigment, a lubricant, carbon black and the like as required. For example, the antioxidant is contained in an amount of 0.1 parts by mass or more and 2 parts by mass or less with respect to 100 parts by mass of the base resin. In this case, excellent heat aging characteristics can be obtained.

[Fiber optic cable]
FIG. 3 is an embodiment of the optical fiber cable according to the present invention, and is a cross-sectional view showing an indoor type optical fiber cable. As shown in FIG. 3, the indoor optical fiber cable 20 has a single-core optical fiber 11, two tension members 12, and a sheath 13 that covers the optical fibers 11 and the tension members 12. The tension member is made of a material having high tensile tension such as a steel wire, and the sheath 13 is made of the flame retardant resin composition of the present invention.

[Method of manufacturing optical fiber cable]
A method of manufacturing the above-described optical fiber cable 20 will be described.

  First, the optical fiber 11, the tension member 12, and the flame retardant resin composition of the present invention are prepared. Next, an optical fiber cable 20 is obtained by coating the optical fiber 11 and the tension member 12 with the flame retardant resin composition of the present invention.

  Specifically, as described above, high-density polyethylene, linear low-density polyethylene, polypropylene-based elastomer, acid-modified polyolefin compound, calcium carbonate particles, silicone-based compound, fatty acid-containing compound, etc. are melted using an extruder or the like. It knead | mixes and obtains the flame-retardant resin composition of this invention. Next, the one-core optical fiber 11 and the two tension members 12 are arranged as shown in FIG. Further, the flame retardant resin composition is extruded from the extruder into a cylindrical shape having a cross-sectional shape shown in FIG. 3, and the sheath 13 is formed by continuously covering the optical fiber 11 and the tension member 12.

  The present invention is not limited to the embodiments described above. That is, the optical fiber cable is not limited to the indoor type optical fiber cable, and any type of cable may be used as long as the flame retardant resin composition of the present invention is applicable.

  Hereinafter, the contents of the present invention will be more specifically described with reference to examples and comparative examples, but the present invention is not limited to the following examples.

(Examples 1 to 15 and Comparative Examples 1 to 6)
Base resin, calcium carbonate particles, silicone masterbatch (silicone MB), fatty acid-containing compound, antioxidant masterbatch (antioxidant MB) are compounded in the amounts shown in Tables 1 to 3 and adjusted to 160 ° C by a Banbury mixer. The mixture was kneaded for 15 minutes to obtain a flame retardant resin composition. In Tables 1 to 3, the unit of the blending amount of each blending component is part by mass. In Tables 1 to 3, although the blending amounts of high density polyethylene, linear low density polyethylene, polypropylene-based elastomer, and acid-modified polyolefin compound are not 100 parts by mass, the resin is also contained in silicone MB and antioxidant MB. The total amount of the base resin is 100 parts by mass if the resin in the silicone MB and the antioxidant MB is added to the high density polyethylene, linear low density polyethylene, polypropylene-based elastomer, and acid-modified polyolefin compound. Become.

Specifically, the following were used as the above-mentioned base resin, calcium carbonate particles, silicone MB, fatty acid-containing compound, and antioxidant MB.
(1) Base resin (A) High density polyethylene (HDPE) (trade name "Novatec HD HD 322 W", manufactured by Japan Polyethylene Corporation, density 951 kg / m ³ )
(B) Linear low density polyethylene (B-1) Linear low density polyethylene (LLDPE 1) (trade name "Umille 0520F", Ube Maruzen Polyethylene Co., density 904 kg / m ³ )
(B-2) Linear low density polyethylene (LLDPE 2) (trade name "Ummement 2515HF", manufactured by Ube Maruzen Polyethylene, density 925 kg / m ³ )
(B-3) Linear low density polyethylene (LLDPE 3) (trade name "Umille 140 HK", manufactured by Ube Maruzen Polyethylene, density 937 kg / m ³ )
(C) Polypropylene-based elastomer (PP-based elastomer) (trade name "Tafmer XM 5070", manufactured by Mitsui Chemicals, Inc.)
(D) Acid-modified polyolefin compound (acid-modified PO) (trade name "Tafmer MA8510", manufactured by Mitsui Chemicals, Inc.)
(2) Calcium carbonate particles (A) (carbonated Ca1) (trade name "NCC-P", manufactured by Nitto Powder Co., Ltd., average particle diameter 1.7 μm)
(B) (carbonated Ca2) (trade name "NCC-P # 2300", manufactured by Nitto Powdering Industry Co., Ltd., average particle diameter 1.0 μm)
(3) Silicone compound (Silicone MB) (trade name "X-22-2125H", manufactured by Shin-Etsu Chemical Co., Ltd., containing 50% by mass silicone gum and 50% by mass PE)
(4) Fatty acid-containing compound (stearic acid Mg) (trade name "Ef Cochem MGS", manufactured by ADEKA)
(5) Antioxidant (antioxidant MB) (trade name "C-174. 2A", manufactured by Dainichi Seika Kogyo Co., Ltd., containing 50% by mass antioxidant and 50% by mass EVA)

(Production of sheet-like compact)
The obtained flame-retardant resin composition was molded using a molding die to obtain a sheet-like molded product having a thickness of 1 mm and a sheet-like molded product having a thickness of 2 mm.

(Preparation of coated wire sample)
The obtained flame retardant resin composition is charged into a single-screw extruder (L / D = 20, screw shape: full flight screw, manufactured by Mars Seiki Co., Ltd.), and a tube-like extrudate is extruded from the extruder to conduct a conductor A coated electric wire sample was obtained by coating a flame retardant resin composition so as to have a thickness of 0.7 mm on (one filament number / cross sectional area 2 mm ² ).

(Preparation of fiber optic cable sample)
The obtained flame retardant resin composition is introduced into a single screw extruder (L / D = 20, screw shape: full flight screw, manufactured by Mars Seiki Co., Ltd.), and the extruder has a cross-sectional shape shown in FIG. By extruding a cylindrical extruded material, the single core optical fiber has a flame diameter of 1.6 mm, a major diameter of 2.0 mm, and a distance of 0.4 mm between the tear notch and the optical fiber. An optical fiber cable sample coated with a resin composition was obtained.

The flame retardant resin compositions of Examples 1 to 15 and Comparative Examples 1 to 6 were evaluated for hardness, easy tearability, low temperature embrittlement property, mechanical property and flame retardance as follows. The
The mechanical properties are evaluated by measuring the breaking strength and the elongation.

<Hardness>
A sample having a size of 20 mm long and 50 mm wide was prepared from the sheet-like molded product having a thickness of 2 mm described above, and Shore D hardness was measured with a durometer (type D) in accordance with JIS K7215. In addition, in the case of a measurement, the number of measurements was set to 5 and what averaged five measurement results was employ | adopted as a measured value. In this example, the Shore D hardness was 50 or more.

<Easy tearability>
Using the above-mentioned fiber optic cable sample, the notch between the jackets of the fiber optic cable sample was previously torn apart by several cm, and both ends that were torn were clamped with a chuck, and this was torn by 200 mm at a tensile speed of 500 mm / min. The tearing force was measured. In addition, in the case of a measurement, the number of measurements was set to 5 and what averaged five measurement results was employ | adopted as a measured value. In this example, the tearing force was 10 N or less.

<Low temperature embrittlement characteristics>
A sample of 6 mm long × 38 mm wide was produced from the above-mentioned sheet-like molded product having a thickness of 2 mm, and an impact test at a low temperature was performed according to JIS C3005. Specifically, an impact resistance test was performed in steps of 0 ° C. to 5 ° C., and the lowest temperature at which cracking did not occur on the sheet surface after impact was taken as the embrittlement temperature. In this example, the embrittlement temperature was −30 ° C. or lower.

<Measurement of breaking strength and elongation>
A No. 3 dumbbell-shaped sample was prepared from the above-mentioned sheet-like molded product having a thickness of 1 mm, and a tensile test was performed according to JIS C3005 to measure the breaking strength and the elongation at break. . In the measurement, the tensile speed was 200 mm / min, the marking interval was 20 mm, the number of measurements was 5, and the average of the results of five measurements was adopted as the measurement value. In this example, the test was passed with a breaking strength of 20 MPa or more and an elongation of 300% or more.

<Flame retardancy>
The above-described coated wire sample was subjected to a 60 ° inclined combustion test in accordance with JIS K3005. The 60 ° inclined combustion test is performed on 10 coated wire samples, and a sample whose fire extinguishing time (unit: seconds) is within 60 seconds is taken as a pass, and the pass rate of 10 coated wire samples is calculated. The average value of fire extinguishing time was determined, and this was taken as the 60 ° inclined burning time. The fire extinguishing time is the time from the end of flame contact (immediately after the burner flame is removed from the electric wire) to the self-extinguishing, and the shorter the fire extinguishing time, the higher the flame retardancy. At this time, flame contact was performed until firing of the coated wire sample occurred within 30 seconds. In this example, the pass rate was 100%.

  From the results shown in Tables 1 to 3, the flame retardant resin compositions of Examples 1 to 15 reached the pass criteria in terms of hardness, easy tearability, low temperature embrittlement characteristics, mechanical characteristics, and flame retardancy. . On the other hand, the flame retardant resin compositions of Comparative Examples 1 to 6 did not reach the acceptance criteria in at least one of hardness, easy tearability, low temperature embrittlement characteristics, mechanical characteristics and flame retardancy. .

  From this, it is confirmed that according to the flame retardant resin composition of the present invention, excellent mechanical properties and flame retardancy can be ensured while securing high hardness, easy tearability and low temperature embrittlement characteristics. It was done.

DESCRIPTION OF SYMBOLS 1 ... Internal conductor 2 ... Insulating layer 3 ... Sheath 4 ... Insulated electric wire 10 ... Cable 11 ... Optical fiber 12 ... Tension member 13 ... Sheath 20 ... Optical fiber cable

Claims (6)

High density polyethylene 25% by mass or more and 70% by mass or less,
10% by mass or more and 55% by mass or less of linear low density polyethylene,
With respect to 100 parts by mass of a base resin containing 10% by mass or more and 25% by mass or less of a polypropylene elastomer and 5% by mass or more and 20% by mass or less of an acid-modified polyolefin compound,
Calcium carbonate particles blended in a proportion of 30 parts by mass or more and 50 parts by mass or less;
A silicone compound compounded in a proportion of 1 part by mass or more and 10 parts by mass or less;
What is claimed is: 1. A flame retardant resin composition comprising: a fatty acid-containing compound blended in a proportion of 2 parts by mass or more and 20 parts by mass or less. The flame retardant resin composition according to claim 1, wherein the density of said high-density polyethylene is less than 945 kg / ^{m 3} or more 970 kg / ^{m 3.} The flame-retardant resin composition according to claim 1 or 2, wherein a density of the linear low density polyethylene is 900 kg / m ³ or more and 940 kg / m ³ or less. With a conductor,
An insulated wire having an insulating layer covering the conductor;
The cable in which the said insulating layer is comprised with the flame-retardant resin composition as described in any one of Claims 1-3. With a conductor,
An insulating layer covering the conductor;
A cable having a sheath covering the insulating layer,
The cable in which at least one of the said insulation layer and the said sheath is comprised with the flame-retardant resin composition as described in any one of Claims 1-3. Optical fiber,
An optical fiber cable having a sheath for covering the optical fiber,
The optical fiber cable comprised by the said flame retardant resin composition as described in any one of Claims 1-3.

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