JP5100284B2 - Flame retardant resin composition, electric wire covering material containing the same, and electric wire covered thereby - Google Patents

Description

  The present invention relates to a flame retardant resin composition, an electric wire covering material containing the flame retardant resin composition, and an electric wire covered thereby.

  Polyolefin-based resins are excellent in physical and chemical properties, and are used in households such as films, sheets, pipes, containers, covered electric wires and cables (hereinafter simply referred to as “electric wires”). Or, it is used for various applications for industrial purposes. However, since polyolefin resin is flammable, for example, a bromine atom or a chlorine atom is contained in the polyolefin resin to make it flame-retardant. In addition, a halogenated flame retardant added is used. However, these halogen-based flame retardants can exhibit a flame-retardant effect with a small amount of blending, but have a drawback of generating harmful halogen gas during combustion.

Therefore, in recent years, there has been proposed a halogen-free flame retardant that does not generate halogen gas during combustion, and is added with a hydrate of an inorganic metal compound such as magnesium hydroxide as a non-polluting flame retardant (patent) References 1 and 2).
Japanese Patent Laid-Open No. 02-053845 Japanese Patent Laid-Open No. 02-145632

However, the flame retardant resin composition to which magnesium hydroxide is added as a main component of the inorganic flame retardant has a specific gravity of about 1.2 to 1.4 g / cm ³ and a large specific gravity. Handling is inconvenient at the time of laying the electric wire, and the transportation cost is high due to the large specific gravity during transportation.

  In addition, the conventional flame retardant resin composition has insufficient wear resistance, and when an optical cable is laid in a pipeline such as an apartment, building, factory, or detached house, it is caused by friction between the pipeline wall and the cable. Otherwise, scratches or wear may occur. Moreover, in order to coat | cover a flame-retardant resin composition and to make an electric wire, the moldability of a flame-retardant resin composition becomes important. Furthermore, it is necessary in terms of safety and the like that the acidity of the gas is low (the pH is high) during combustion. In addition, the characteristics required for the electric wires are defined in JIS and the like, and these must be satisfied.

  Therefore, the present invention provides a flame retardant resin composition having a small specific gravity, excellent wear resistance and molding processability, and low gas acidity, a wire covering material containing the same, and a wire covered with the same. For the purpose.

The present invention contains a high density polyethylene having a density of 0.950 g / cm ³ or more and a molecular weight distribution (Mw / Mn) of 15 or more, 2 to 5 wt% red phosphorus, and a specific gravity of 1.05 g. / Cm ³ or less. Moreover, it is an electric wire coating | covering material characterized by including the said flame-retardant resin composition, It is an electric wire characterized by coat | covering with the said electric wire coating | covering material.

As described above, according to the present invention, a flame retardant resin composition having a small specific gravity, excellent wear resistance and molding processability, and low gas acidity, a wire covering material containing the flame retardant resin composition, and a coating with the flame retardant resin composition. Electric wires can be provided.

The flame retardant resin composition according to the present invention has a specific gravity of 1.05 g / cm ³ or less, preferably 0.95 to 1.03. Since the specific gravity of the flame retardant resin composition according to the present invention is light, it can be suitably used as a wire coating material.

The flame retardant resin composition according to the present invention contains high-density polyethylene. The high density polyethylene has a density of 0.950 g / cm ³ or more, preferably 0.955 to 0.965. If the density is low, the wear resistance is poor. The molecular weight distribution (Mw / Mn) is 15 or more, preferably 20 or more. If the molecular weight distribution is low, high-speed moldability and mechanical properties cannot be maintained. The molecular weight distribution can be determined using GPC (gel permeation chromatography). Such high-density polyethylene can be produced using a known method, and can be obtained, for example, by polymerizing ethylene using a Ziegler catalyst or a metallocene catalyst.

  The flame retardant resin composition according to the present invention contains red phosphorus. Commercially available red phosphorus can be used.

  The flame-retardant resin composition according to the present invention may contain a polyolefin other than the high-density polyethylene. Such polyolefin resins are not particularly limited, but homopolymers or copolymers of α-olefins such as ethylene, propylene, butene-1, 4-methylpentene-1, hexene-1, octene-1 and the like. Ethylene copolymer of ethylene and polar monomer, specifically, single copolymer such as high / medium / low density / ultra low density polyethylene (excluding the high density polyethylene), polypropylene, polybutene-1, etc. Copolymers, copolymers of ethylene and propylene, butene-1,4-methylpentene-1, hexene-1, octene-1, etc., copolymers of propylene and ethylene, ethylene and vinyl esters, α, β-unsaturated Examples thereof include ethylene copolymers with carboxylic acids and / or alkyl esters thereof. Among these, an ethylene copolymer is preferable. Examples of the ethylene copolymer include an ethylene-vinyl acetate copolymer (EVA), an ethylene-ethyl acrylate copolymer (EEA), and an ethylene-methyl acrylate copolymer. Copolymer (EMA), ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester copolymer, ethylene- (meth) acrylic acid ester copolymer rubber, ethylene- (meth) acrylic acid ester- There are (meth) acrylic acid copolymer rubber (acrylic rubber) and ethylene / α-olefin copolymer. These may be used alone or in combination of two or more. Among these, ethylene-vinyl acetate copolymer (EVA) is particularly preferable from the viewpoint of flame retardancy and mechanical properties.

  In the ethylene-based copolymer, the content of a copolymerization component copolymerized with ethylene for improving flame retardancy (for example, VA content in ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer) In coalescence, the EA content) is preferably 8 to 40 w%, more preferably 12 to 35 w%. Moreover, MFR (melt flow rate, based on JIS K7210, 190 ° C./2.16 kg) of the polyolefin resin is 0.05 to 20 g / 10 minutes from the viewpoint of strength and kneadability of the resin composition. More preferably, about 0.1-10 g / 10 minutes is preferable.

The flame retardant resin composition according to the present invention may contain a functional group-containing compound-modified ethylene resin. As the functional group-containing compound-modified ethylene-based resin, a functional group-containing compound selected from unsaturated carboxylic acids or derivatives thereof, epoxy group-containing compounds, hydroxyl group-containing compounds, amino group-containing compounds, organic silane compounds, and organic titanate compounds. Examples thereof include those modified with at least one kind, and ethylene-based resins modified with an unsaturated carboxylic acid or a derivative thereof are particularly preferable.

  Examples of the unsaturated carboxylic acid or derivative thereof used for modification include unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, furanic acid, crotonic acid, vinyl acetic acid, pentenoic acid; maleic acid, fumaric acid, citraconic acid, There are α, β-unsaturated dicarboxylic acids or anhydrides such as itaconic acid or metal salts thereof, and maleic acid or its anhydride is particularly preferable.

  The content of the functional group-containing compound in the functional group-containing compound-modified ethylene resin is preferably 0.01 to 10 wt%, more preferably 0.05 to 5.0 wt%. If the content is less than 0.01 wt%, the coupling effect between the resin and the flame retardant may not be exhibited. Moreover, when exceeding 10 wt%, when denatured, there exists a possibility that decomposition | disassembly and a crosslinking reaction may occur simultaneously.

  The functional group-containing compound-modified ethylene resin can be obtained by adding a functional group-containing compound and an organic peroxide to an unmodified polyethylene resin and mixing them by heating. The content of the functional group-containing compound is obtained by mixing the unmodified ethylene-based resin with a functional group-containing compound content of 0.01 to 10 wt% by modification by heating mixing or a modified product having a larger content. What was adjusted to the said range is used.

  The flame retardant resin composition according to the present invention may contain an inorganic flame retardant. Inorganic flame retardants include inorganic salts and metal hydrates. Inorganic salts include calcium carbonate, calcium sulfate, calcium silicate, calcium phosphate, zircon oxide, titanium oxide, zinc oxide, magnesium oxide, magnesium carbonate, barium sulfate, barium borate, barium metaborate, zinc borate, zinc metaborate, Examples thereof include molybdenum disulfide, antimony trioxide, antimony pentoxide, clay, diatomaceous earth, kaolinite, montmorillonite, hydrotalcite, talc, silica, white carbon, zeolite, and hydromagnesite. Examples of the hydrated metal oxide include magnesium hydroxide, aluminum hydroxide, hydrotalcite, calcium hydroxide, and barium hydroxide. Magnesium hydroxide is preferred from the viewpoint of low temperature impact resistance and workability.

  As the inorganic flame retardant, a surface-treated agent may be used. As the surface treatment agent, fatty acid and fatty acid metal salt or a mixture thereof, as well as a surface treatment agent such as fatty acid ester, wax or modified product thereof, curable resin, organic silane, organic titanate, and organic borane, polycarboxylic acid type Examples include dispersants, polyglycerin derivatives, N-acyl basic amino acids, dibasic acid erythritol esters, phosphate esters, phosphite esters, alcohol phosphate esters, and other phosphorus compounds.

  The flame retardant resin composition according to the present invention may contain a flame retardant aid. Flame retardant aids include silicone powders, silicone compounds such as silicone gum, phosphorus flame retardants such as tricresyl phosphate, triphenyl phosphate, phosphate ester, ammonium polyphosphate, zinc borate, zinc hydroxystannate, stannic acid Examples thereof include zinc compounds such as zinc, nitrogen-containing organic flame retardants such as melamine cyanurate and melamine, maleimide compounds such as carbon black and N, N′-m-phenylene dimaleimide, antimony trioxide, and antimony pentoxide.

The flame retardant resin composition according to the present invention can be blended with various additives and auxiliary materials in accordance with the intended use within a range that does not impair the characteristics. These various additives and auxiliary materials include scratch whitening inhibitors, stabilizers, antioxidants, UV absorbers, light stabilizers, antistatic agents, lubricants, processability improvers, fillers, dispersants, copper damage Examples thereof include an inhibitor, a neutralizer, a foaming agent, an anti-bubble agent, a colorant, and carbon black. Moreover, it can also bridge | crosslink by adding a crosslinking agent, for example, an organic peroxide, sulfur, a silane type crosslinking agent, and a crosslinking adjuvant, or can be bridge | crosslinked by irradiating ionizing radiation.

  The content of high-density polyethylene in the flame-retardant resin composition according to the present invention is preferably 45 to 98 wt%, more preferably 60 to 95 wt%, and particularly preferably 70 to 90 wt%. The content of red phosphorus is 2 to 5 wt%, preferably 3 to 5 wt%. When the content of red phosphorus is less than 2 wt%, the flame retardancy is lowered, and when it exceeds 5 wt%, the low temperature impact resistance and tensile properties are lowered. The content of polyolefin other than high-density polyethylene is preferably 30 wt% or less, more preferably 20 wt% or less, and particularly preferably 5 to 10 wt%. The content of the inorganic flame retardant is preferably 10 wt% or less, more preferably 8 wt% or less, and particularly preferably 1 to 6 wt%.

  The flame-retardant resin composition according to the present invention can be obtained by melt-kneading each of the above components with a commonly used kneading apparatus such as a twin-screw kneading extruder, a Banbury mixer, a kneader, or a roll.

  The electric wire according to the present invention includes a conductor, an optical fiber, a tension member, a support wire (hereinafter referred to as a conductor) and a coating layer, and the conductor is covered with the coating layer. There are no particular restrictions on the diameter or material of the conductor, such as a conductor, and it is appropriately determined according to the application. The thickness of the coating layer containing the flame retardant resin composition formed around the conductor or the like is not particularly limited, but is preferably 0.15 to 5 mm. The coating layer may have a multilayer structure, and may have other layers such as an intermediate layer in addition to the coating layer formed of the resin composition of the present invention.

  The electric wire according to the present invention can be manufactured by extruding the electric wire covering material according to the present invention as an insulating layer or a sheath layer and covering the conductor. These electric wire covering materials and electric wires can improve not only heat resistance but also flame retardancy by making the covering layer a crosslinked body. In that case, the flame-retardant resin composition according to the present invention can be produced by coating an extruded conductor using a normal electric wire production extruder and then crosslinking the coating layer. The method for crosslinking is not particularly limited, and can be performed by an electron beam crosslinking method or a chemical crosslinking method. When the electron beam crosslinking method is used, the dose of the electron beam is suitably 1 to 30 Mrad, and in order to perform crosslinking efficiently, a methacrylate compound such as trimethylolpropane triacrylate, an allyl compound such as triallyl cyanurate, You may mix | blend polyfunctional compounds, such as a maleimide type compound and a divinyl type compound, as a crosslinking adjuvant. In the case of the chemical crosslinking method, an organic peroxide such as a resin composition, hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxy ester, ketone peroxy ester, or ketone peroxide is blended as a crosslinking agent, followed by heat treatment after extrusion coating. Do.

Next, examples of the flame retardant resin composition according to the present invention will be described. The following raw materials were used in the flame retardant resin composition according to this example and the comparative example.
(1) High density polyethylene (referred to as HDPE)
MFR: 0.17 g / 10 min, density: 0.956 g / cm ³ , Mw / Mn = 20 (manufactured by Keiyo Polyethylene)
(2) Linear low density polyethylene (referred to as L-LDPE)
MFR: 4 g / 10 min, density: 0.944 g / cm ³ , Mw / Mn = 8 (manufactured by Ube Maruzen Polyethylene)
(3) Ethylene-vinyl acetate copolymer (referred to as EVA)
MFR: 2 g / 10 min, VA content: 21% by weight (manufactured by Ube Maruzen Polyethylene)
(4) Maleic anhydride modified linear low density polyethylene (referred to as MAH-LL)
MFR: 1.5 g / 10 min, density 0.920 g / cm ³ ,
Maleic anhydride content: 0.1% by weight (manufactured by Ube Maruzen Polyethylene)
(5) Red phosphorus (Novared 120UF manufactured by Rin Chemical Industry Co., Ltd.)
(6) Magnesium hydroxide (referred to as Mg (OH) ₂ )
Kisuma 5B (Kyowa Chemical Industry)
(7) Lubricant Magnesium stearate (Nippon Yushi)
(8) Pigment VULCAN9A32 (manufactured by Cabot)

Example 1:
In the formulation shown in Table 1, so that HDEP, EVA, red phosphorus, and Mg (OH) ₂ are 100 wt%, the lubricant is 0.5 parts by weight and the pigment is 2 parts by weight with respect to 100 parts by weight of the formulation. After being kneaded at 165 ° C. for 5 minutes with a Banbury mixer, the mixture is kneaded at 180 ° C. for 7 minutes with a roll kneader, granulated, and pelletized to obtain a flame retardant resin composition according to Example 1. It was.

Example 2 and Comparative Examples 1 to 3:
A flame retardant resin composition according to Example 2 and Comparative Examples 1 to 3 was obtained in the same manner as in Example 1 except that the raw materials listed in Table 1 were used as the blend.

Using the flame retardant resin compositions according to Examples 1 and 2 and Comparative Examples 1 to 3, a sheet was prepared by molding at 180 ° C. and 100 kg / cm ² for 3 minutes from a hot press molding machine. Using the obtained sheet, MFR, specific gravity, tensile strength, tensile elongation, embrittlement temperature, smoke generation concentration, and generated gas acidity were measured under the following conditions. The results are shown in Table 1.

  Using the flame-retardant resin compositions according to Examples 1 and 2 and Comparative Examples 1 to 3, a single-screw extruder (screw diameter: φ20 mm), one-hole die (hole diameter: φ2.0 mm), set temperature: A strand having an outer diameter of about 2.5 mm was prepared as a cable simulation sample at 160 to 200 ° C., screw rotation speed: 40 rpm, take-up speed: 4 to 6 m / min, and evaluation test of wear resistance, extrusion appearance, and combustion test Was measured under the following conditions. The results are shown in Table 1.

Evaluation test method (1) MFR
The measurement was performed according to JIS K7210. The measurement conditions were a load of 2.16 kg and a measurement temperature of 190 ° C.
(2) Measured by specific gravity water replacement method.
(3) Tensile strength and tensile elongation sheets having a thickness of 1 mm were used, punched with a No. 3 dumbbell specified by JIS K6301, and measured at a test speed of 50 mm / min.
(4) A brittle temperature sheet having a thickness of 2 mm was used and measured according to JIS K7216. The results are expressed in terms of the embrittlement temperature, but this value means that the lower the impact at low temperature, the better.
(5) Wear resistance Using the strand, the outer diameter of the strand was measured before and after a wear test at 2000 rpm in accordance with JIS C3005. A case where the difference between the outer diameter before the wear test and the outer diameter after the wear test was 0.5 mm or less was evaluated as ◯.
(6) Extrusion appearance Using the strand, the center line average roughness (Ra) of the strand surface was measured according to JIS B0601. The case of Ra ≦ 2.0 μm was evaluated as ◯.
(7) Combustion test It measured based on the 60 degree inclination test of JIS C3005 using the said strand. The case where the fire was extinguished within 60 seconds was evaluated as ◯.
(8) Smoke density The smoke density Ds was measured according to JCS 7397.
(9) Generated gas acidity In accordance with JIS C3662-2, the acidity (pH) of the generated gas during combustion was measured.
(10) Judgment The case where the specific gravity, tensile strength, tensile elongation, embrittlement temperature, abrasion resistance, extrusion appearance, combustion test, smoke generation amount and generated gas acidity all fall within the following ranges was judged as ◯.
Specific gravity: 1.05 g / cm ³ ≧
Tensile strength: 10 MPa ≦ (flame resistant cable standard such as JCS 4418)
Tensile elongation: 350% ≤ (flame resistant cable standard such as JCS 4418)
Embrittlement temperature: -60 ° C ≥ (low temperature impact resistance in cold regions)
Abrasion resistance: (outer diameter before abrasion test)-(outer diameter after abrasion test) ≤ 0.5 mm
Extrusion appearance: Ra ≦ 2.0 μm
Combustion test: Fire extinguishing within 60 seconds (flame-resistant cable standards such as JCS 4418)
Smoke concentration: Ds ≦ 150 (Flame resistant cable standard such as JCS 4418)
Generated gas acidity: pH ≧ 4.3 (JIS C3662-2)

表１に示すように、実施例１及び２に係る難燃性樹脂組成物は、特に、比重、耐摩耗性、押出外観、及び発生ガス酸性度いずれにおいても優れているが、比較例１乃至３に係る難燃性樹脂組成物は、少なくともいずれかにおいて劣っていることが分かる。

As shown in Table 1, the flame retardant resin compositions according to Examples 1 and 2 are particularly excellent in any of specific gravity, abrasion resistance, extrusion appearance, and generated gas acidity. It can be seen that the flame retardant resin composition according to No. 3 is inferior at least in any one.

Claims (3)

High density polyethylene having a density of 0.950 g / cm ³ or more and a molecular weight distribution (Mw / Mn) of 15 or more, ethylene-vinyl acetate copolymer (EVA) 5 to 30 wt%, red phosphorus 2 A flame retardant resin composition comprising 5 wt% and an inorganic flame retardant of 10 wt% or less and having a specific gravity adjusted to 1.05 g / cm ³ or less. An electric wire covering material comprising the flame retardant resin composition according to claim 1 . An electric wire coated with the electric wire covering material according to claim 2 .