JPH10245459A - Flame retardant resin composition, and electric wire/ cable using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a flame retardant resin composition suitable for an insulating layer for an electric wire/cable, capable of suppressing the whitening by CO2 , and excellent in mechanical properties, flame retardant property and extrusion processability. SOLUTION: This flame retardant resin composition contains 50-200 pt.wt. (C) based on 100 pts.wt. total of 70-00 pt.wt. (A) and 30-1 pt.wt. (B). (A) A syndiotactic polypropylene (s-PP) obtained by polymerizing propylene by using a single site catalyst and having (a) >=0.7 pentad fraction and (b) 0.1-20g/10min melt flow rate(MFR). (B) A polyolefinic resin modified with a monomer containing an acid anhydride group by 0.1-3wt.%. (C) Magnesium hydroxide satisfying either one of conditions (1) or (2). (1) (a) A hexagonal plate like particles, (b) Having 0.5-2.0μm mean particle diameter, and <=5μm maximum particle diameter and (c) Using a fatty acid or a phosphate ester as a surface treating agent, (2) (a) Amorphous flat particles, (b) Having 2-6μm mean particle diameter and (c) Using the fatty acid or the phosphate ester as the surface treating agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant resin composition and an electric wire / cable using the same.

[0002]

2. Description of the Related Art As a technique relating to a flame-retardant resin composition,
The invention described in JP-A-8-3393 is known. This is a flame-retardant resin composition comprising a syndiotactic polypropylene having a syndiotactic pentad fraction (rrrr) of 0.7 or more and a melt flow rate (MFR) of 0.1 to 20 g / 10 minutes and a flame retardant. Is disclosed.

[0003]

However, the above technique has the following problems. In a flame retardant composition using an inorganic flame retardant such as a metal hydrate, a large amount of the inorganic flame retardant must be added in order to satisfy high flame retardancy. When syndiotactic polypropylene is used as the base resin, the mechanical properties are improved, but the processability is reduced. For example, when this composition is used for coating an electric wire, the extrusion linear speed does not increase.

When magnesium hydroxide is used as an inorganic flame retardant, whitening occurs on the surface of the composition. Inorganic flame retardants and syndiotactic polypropylene inherently lack interfacial affinity. When a large amount of the inorganic flame retardant is added, the effect of the lack of interfacial affinity becomes remarkable, and surface bleeding of magnesium hydroxide easily occurs. Therefore, the surface-bleed magnesium hydroxide reacts with CO ₂ in the atmosphere to form white solid magnesium carbonate, and the material surface becomes white.

Accordingly, a main object of the present invention is to provide a flame-retardant resin composition which can suppress whitening due to CO ₂ and which has excellent mechanical properties, flame retardancy and extrudability, and an electric wire and a wire using this composition. Cable and to provide.

[0006]

Means for Solving the Problems The present inventors have made various studies in view of the above circumstances, and as a result, have found that a specific syndiotactic polypropylene and a polyolefin modified with an acid anhydride group-containing monomer in an amount of 0.1 to 3% by weight are obtained. The inventors have found that the above object can be achieved by blending a predetermined amount of magnesium hydroxide having a limited diameter and shape, and have completed the present invention.

That is, the characteristics of the flame-retardant resin composition of the present invention are as follows: (C) 50 to 100 parts by weight of (A) 70 to 99 parts by weight and (B) 30 to 1 part by weight. Contains 200 parts by weight. (A) Syndiotactic polypropylene obtained by polymerizing propylene using a single-site catalyst and satisfying the following conditions: Syndiotactic pentad fraction (rrrr) of 0.7 or more; Melt flow rate (MFR) of 0.1 to 20 g / 10 Min (190 ° C) (B) Polyolefin resin with acid anhydride containing monomer
0.1 to 3% by weight modified polyolefin (C) Magnesium hydroxide that satisfies any of the following conditions (1) and (2) (1) Hexagonal plate-shaped particles Average particle size is 0.5 to 2.0 μm and maximum particle size 5μm or less Fatty acid or phosphate ester used as surface treatment agent (2) Amorphous flat particles Average particle size is 2-6μm Use fatty acid or phosphate ester as surface treatment agent

Further, the electric wire / cable of the present invention is characterized in that the above-mentioned flame-retardant resin composition is provided as a coating layer. For example, in an electric wire having an insulating layer on a conductor,
The insulation layer itself or a sheath provided on the insulation layer is made of the above-described flame-retardant resin composition. In a cable in which a three-core cable core is collectively covered with a sheath, the sheath is made of the above-mentioned flame-retardant resin. And a composition. Further, an optical cable having a coating layer of the above flame-retardant resin composition and a composite cable of an optical fiber and an electric wire are also included in the scope of the present invention.

The details of the main raw materials and the reasons for limiting the conditions in the above inventions are as follows. Polypropylene (A)
Those having a syndiotactic pentad fraction of 0.7 or more have excellent mechanical properties. It is more preferably 0.8 to 0.95 from the viewpoint of flexibility. The melt flow rate is 0.1
Those having a thickness of up to 20 g / 10 minutes are suitable for extrusion processing of electric wires and the like.
Particularly, 0.5 to 10 g / 10 minutes is preferable.

[0010] The use of such syndiotactic polypropylene (A) can provide a material having excellent mechanical properties. However, if a large amount of magnesium hydroxide is used as a flame retardant, the workability is poor and the problem of surface whitening is also encountered. Occur. To solve this problem, a polyolefin (B) was blended. If the amount of the polyolefin (B) is less than 1 part by weight, there is little effect on improving workability and suppressing surface whitening. Conversely, if it exceeds 30 parts by weight, when used as a coating layer of an electric wire, the coating layer is stripped from the conductor. It becomes difficult.

Syndiotactic polypropylene (A)
Various known single-site catalysts can be used for the synthesis of. For example, a catalyst composition containing a lanthanoid-based metal belonging to Groups 3 to 10 of the periodic table, a metal coordination complex, and an activating cocatalyst (Japanese Patent Application Laid-Open No. 6-306121) can be mentioned.

Polyolefin (B) obtained by modifying a polyolefin resin with an acid anhydride group-containing monomer in an amount of 0.1 to 3% by weight.
As described above, the amount of compounding and the amount of modification were limited from the viewpoint of improving processability and suppressing surface whitening. For example, those obtained by graft polymerization of maleic anhydride to polyolefin are mentioned.

The reason why the amount of magnesium hydroxide (C) is limited is that if the amount is less than 50 parts by weight, sufficient flame retardancy cannot be obtained (it does not pass the vertical tray combustion test). If it exceeds, the mechanical strength decreases.

Among the magnesium hydroxides (C), amorphous ones can be obtained by pulverizing brucite ore, and hexagonal ones can be obtained by industrial synthesis by known means. .

If the average particle size is less than 2 μm, the particles will aggregate and cause poor dispersion, and if the average particle size exceeds 6 μm, poor dispersion will result. This amorphous magnesium hydroxide has
It is preferable that iO ₂ CaO and CaCO ₃ be contained in an amount of 1 to 2% by weight in terms of CaO, and Fe ₂ O ₃ be contained in an amount of 0.1 to 1.0% by weight. As a result, the acid resistance can be improved.

The hexagonal plate has a maximum particle size of 5 μm.
If it exceeds m, it becomes a fracture origin and tends to decrease the strength. If the average particle size is less than 0.5 μm, the particles will aggregate to cause poor dispersion, and conversely, if it exceeds 2 μm, poor dispersion will result.

It is necessary to use those magnesium hydroxide (C) which has been subjected to a surface treatment. As surface treatment agents, lauric acid, stearic acid, oleic acid,
Fatty acids such as palmitic acid and phosphates such as triphenyl phosphate and tricresyl phosphate are exemplified.
These surface treatment agents are particularly desirable in view of dispersibility of magnesium hydroxide.

The resin composition of the present invention may further comprise, if necessary, red phosphorus, an inorganic filler, an antioxidant,
An appropriate amount of a stabilizer, an ultraviolet ray inhibitor, a copper damage inhibitor, a lubricant, a pigment and the like may be blended. Examples of the inorganic filler (D) include calcium carbonate, clay, calcium silicate, talc, alumina, metal powder (fiber), glass powder (fiber), and carbon fiber.

[0019]

Embodiments of the present invention will be described below. After each blend material shown in Table 1 to obtain a kneaded processed to compositions by an open roll, "workability", "adhesion between the coating material and the conductor", "CO ₂ whitening", "flame retardant" Was evaluated. Table 1 also shows the test results. The method and evaluation criteria for each test are as follows.

[Workability] An electric wire having a conductor diameter of 1.2 mm and a coating thickness of 0.8 mm is extruded with a 50 mmφ extruder (L / D = 24). At that time, measure the line speed at which the wire surface becomes rough,
Those with a line speed of 20 m / min and no roughness were rated "good", and those with roughness were rated "impossible".

"Adhesion between the covering material and the conductor" When the covering material is peeled off from the conductor with the above-mentioned electric wire, the case where the covering material comes off is "good".
A case in which the film did not come off and adhered was regarded as “impossible”.

"CO ₂ whitening" The above-mentioned electric wire is 100% CO ₂
Leave in gas for 48 hours and measure weight change. When the weight increase was less than 0.1% by weight, the whitening of the electric wire surface was inconspicuous visually.

The preparation of "flame retardant" nominal cross section of 38mm ² for wire and cable, "good" and those that pass the vertical tray combustion test specified in IEEE 383, was rejected as the "impossible".

[0024]

[Table 1]

As shown in Table 1, Examples 1 to 6 passed all the tests. On the other hand, Comparative Example 1 containing no acid anhydride-modified polymer (B) was unacceptable in terms of processability and surface whitening. In Comparative Example 2 in which the amount of the acid anhydride-modified polymer (B) was large, the coating material was not strippable. Further, Comparative Example 3, in which the amount of magnesium hydroxide (C1) was small, was not flame-retardant.

[0026]

As described above, the flame-retardant resin composition of the present invention has the following effects. Whitening due to CO ₂ can be suppressed. By specifying the shape and particle size of magnesium hydroxide and increasing the affinity between magnesium hydroxide and the base resin, the reaction between magnesium hydroxide and CO ₂ is suppressed to prevent whitening.

Excellent extrudability. In particular, when the composition of the present invention is used as a covering material for electric wires and cables, it is effective for improving the productivity of electric wires and cables.

When used as a covering material for an electric wire, it can be easily peeled off from the conductor. Therefore, the terminal / intermediate connection work of the electric wire / cable can be easily performed.

It has sufficient flame retardancy. It has flame retardancy that can pass the vertical tray combustion test and can be used in various fields where flame retardancy is required, such as electric cables and other electronic components.

Claims (3)

[Claims] (1) 70-99 parts by weight of (A) and (B) 30
A flame-retardant resin composition comprising (C) 50 to 200 parts by weight with respect to 100 parts by weight of 1 to 1 part by weight.
(A) Syndiotactic polypropylene obtained by polymerizing propylene using a single-site catalyst and satisfying the following conditions: Syndiotactic pentad fraction (rrrr) of 0.7 or more; Melt flow rate (MFR) of 0.1 to 20 g / 10 (B) Polyolefin resin is converted to an acid anhydride group-containing monomer
0.1 to 3% by weight modified polyolefin (C) Magnesium hydroxide that satisfies any of the following conditions (1) and (2) (1) Hexagonal plate-shaped particles Average particle size is 0.5 to 2.0 μm and maximum particle size 5μm or less Fatty acid or phosphate ester used as surface treatment agent (2) Amorphous flat particles Average particle size is 2-6μm Use fatty acid or phosphate ester as surface treatment agent 2. An electric wire or cable comprising a coating layer of the flame-retardant resin composition according to claim 1. 3. An optical cable comprising a coating layer of the flame-retardant resin composition according to claim 1.