JPH09216971A - Flame-retardant resin composition and cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a nonhalogen flame-retardant resin compsn. improved in burning distance, dripping during burning, and burning time by compounding a nonhalogenated polyolefin resin with magnesium hydroxide, a zinc compd., and carbon fibers. SOLUTION: This compsn. comprises 100 pts.wt. nonhalogenated polyolefin resin, 50-150 pts.wt. magnesium hydroxide, 20-50 pts.wt. zinc compd., and 10-50 pts.wt. carbon fibers. Usable examples of the zinc compd. are zinc oxide and zinc borate, the former being esp. pref. The compsn. can be used for covering a conductor to give a flame-retardant cable. The compsn. may cover a conductor directly or through another nonhalogenated resin layer or may be a sheath, the outermost layer of a cable. Thus formed cable may further be covered with another layer such as formed from a nonhalogenated resin.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a flame-retardant resin composition and a flame-retardant cable.

[0002]

2. Description of the Related Art Conventionally, halogen-containing materials such as polyvinyl chloride and chloroprene rubber exhibiting flame retardancy have been used as materials required to have flame retardancy such as insulating materials for electric and electronic products, home electric appliances, automobile interior materials, etc. Synthetic resins have been widely used, but there is a problem that toxic gas is generated under high heat.

On the other hand, in order to impart flame retardancy to a halogen-free synthetic resin and further improve its flame retardancy,
Further, in order to improve the flame retardancy of halogen-containing synthetic resins, it is often practiced to add a flame retardant to the synthetic resins.

As the flame retardant, tricresyl phosphate, plasticizer such as chlorinated paraffin, antimony trioxide, metal oxide, ammonium phosphate, inorganic compound such as boric acid, brominated polyolefin, phosphorus-containing polyol, halogenated anhydrous. Reactive flame retardants such as phthalic acid are used.

[0005]

However, as mentioned above, halogen-containing flame retardants are often used as described above, and even resin compositions to which these flame retardants have been added do not burn under high heat. The harmful effect of generating toxic gas still remains, and there is a strong demand for a flame-retardant resin composition containing no halogen.

On the other hand, in a flame-retardant cable having such a flame-retardant resin composition as a covering material, the sheath layer has flame retardancy as well as the insulation layer of the inner core. Even if it does, it may fail the combustion test. Reasons for the failure include long burning distance of the cable, dropping of the burning coating material, burning time, and the like.

[0007] That is, the present invention provides a halogen-free flame-retardant resin composition having improved burning distance, burning drop property and burning time, and a flame-retardant cable using the composition as a coating material. To aim.

[0008]

Means for Solving the Problems As a result of intensive studies, the present inventor has used a halogen-free polyolefin resin as a raw material synthetic resin, and using magnesium hydroxide,
The present invention has been completed by finding that a composition containing a zinc compound and carbon fiber can achieve the object of the present invention.

That is, the present invention comprises (1) 100 parts by weight of a halogen-free polyolefin resin, 50 to 150 parts by weight of magnesium hydroxide, 20 to 50 parts by weight of a zinc compound, and 10 to 50 parts by weight of carbon fiber. The gist is a flame-retardant resin composition and (2) a flame-retardant cable obtained by coating a conductor with at least the above resin composition.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION It is essential that the polyolefin resin used in the present invention does not contain halogen. Examples of such resins include polyolefin, ethylene-vinyl acetate copolymer, and olefin- (meth). Examples thereof include acrylate copolymers and ionomers.

Polyolefins include polyethylene (low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, etc.) (PE), polypropylene (homopolypropylene, ethylene-propylene random copolymer, ethylene-propylene block copolymer). Polymers etc.) (PP), polybutene-1, polyhexene-1, polymethylpentene-1 and the like.

As the olefin- (meth) acrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl methacrylate copolymer Etc.

These polyolefin resins are not limited to one kind, and two or more kinds can be used.

As the zinc compound, zinc oxide, zinc borate and the like can be used, but zinc oxide is particularly preferable. The zinc compound is not limited to one type, and two or more types can be used. The addition of the zinc compound acts as a shell when burning,
It delays combustion and is effective in preventing falling objects.

As the carbon fiber, not only carbonized from polyacrylonitrile (PAN) or pitch as a raw material but also graphite fiber which is further graphitized by heating at a higher temperature can be used. Carbon fiber has high thermal conductivity,
Its use has the effect of making it difficult to reach the ignition temperature and thus making the resin difficult to ignite. Particularly, graphite fiber is preferable because its effect is great.

The resin composition of the present invention contains 5 parts by weight of magnesium hydroxide based on 100 parts by weight of the above polyolefin resin.
0 to 150 parts by weight, 20 to 50 parts by weight of a zinc compound, and 10 to 50 parts by weight of carbon fiber are added.

If the amount of magnesium hydroxide is less than 50 parts by weight, the oxygen index will decrease, leading to a decrease in flame retardance.
If it exceeds the weight part, the Mooney viscosity becomes high and the extrudability of the composition is poor, and since magnesium hydroxide has a water absorbing property, it easily foams at the time of extruding the composition.

If the amount of the zinc compound is less than 20 parts by weight, the shell-forming property is low and the shell is dropped during combustion.

When the amount of carbon fiber is less than 10 parts by weight, the ignition time is shortened, and when it exceeds 50 parts by weight, the tensile elongation of the composition tends to decrease.

The composition of the present invention can be produced by mixing the above-mentioned components with a conventional mixer such as a ribbon blender, a Henschel mixer, or a Brabender Plastograph (registered trademark). It may be produced by kneading the above-mentioned components in an extruder or the like at a temperature not lower than the melting temperature of the above-mentioned polyolefin resin.

The composition of the present invention comprises each of the above-mentioned components, and further, if necessary, various additives commonly used in each field in which the composition is used can be added. Be free. Typical additives include antioxidants, ultraviolet absorbers, light stabilizers, colorants, antistatic agents, antiblocking agents and the like.

Since the composition of the present invention exhibits excellent flame retardancy, it can be used as a material in various fields where its performance is required. Examples thereof include electric / electronic parts, insulating materials for products, interior / exterior materials such as home electric appliances and office supplies, and interior materials for vehicles such as automobiles.

Furthermore, the present invention relates to a flame-retardant cable. The flame-retardant cable of the present invention is formed by coating the outside of a conductor with at least the above composition. Therefore, the conductor may be coated with the above composition directly or through another resin containing no halogen, or the sheath which is the outermost layer of the cable may be the above composition. Further, it is possible to provide another layer such as a resin containing no halogen on the outside of these cables.

[0024]

EXAMPLES The present invention will be described in detail below with reference to examples.

The physical properties were measured according to the following test methods.

Oxygen index JIS K7201 Combustion test IEEE 383 Tensile elongation JIS K7113

(Examples 1 to 3) Ethylene-vinyl acetate copolymer (EVA), magnesium hydroxide, zinc oxide, zinc borate, carbon fiber (manufactured by Mitsubishi Chemical Corporation, trade name Dilead), and antioxidant (Asahi). Denka Kogyo KK, trade name ADEKA STAB AO-50) was supplied to the extruder at the ratio shown in Table 1,
Melt kneading was performed to produce pellets composed of the composition of the present invention.

A test piece was prepared using the obtained pellet, and the oxygen index and tensile elongation were measured. The results are shown in Table 1.

An insulating layer made of low-density polyethylene was provided on the outer side of the conductor, and the sheath of the protective layer was formed on the outer side of the insulating layer to manufacture the cable of the present invention. A flame test was conducted on the obtained cable, and the results are shown in Table 1.

Comparative Examples 1 to 3 Pellets were molded in the same manner as in Examples 1 to 3 except that the components shown in Table 1 were used, and the physical properties thereof were measured and shown in Table 1. As the red phosphorus-based flame retardant, Noval Red 120 manufactured by Rin Kagaku Kogyo Co., Ltd. was used.

Using the pellets obtained above, cables were manufactured in the same manner as in Examples 1 to 3, and the physical properties thereof were measured and shown in Table 1.

(Comparative Example 4) Pellets were molded in the same manner as in Example 3 except that the amount of carbon fiber used was changed as shown in Table 1, and the physical properties thereof were measured and shown in Table 1.

Further, using the pellets obtained above, cables were manufactured in the same manner as in Examples 1 to 3, and the physical properties thereof were measured and shown in Table 1.

[0034]

[Table 1]

[0035]

INDUSTRIAL APPLICABILITY The resin composition of the present invention has a greatly improved burning distance, burning time and burning fallen substances in a burning test.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H01B 7/34 H01B 7/34 B

Claims (3)

[Claims] 1. A halogen-free polyolefin resin 1
00 parts by weight, magnesium hydroxide 50 to 150 parts by weight,
A flame-retardant resin composition comprising 20 to 50 parts by weight of a zinc compound and 10 to 50 parts by weight of carbon fiber. 2. The resin composition according to claim 1, wherein the zinc compound is zinc oxide or zinc borate. 3. A flame-retardant cable obtained by coating a conductor with at least the resin composition according to claim 1 or 2.