JP2810353B2 - Heat resistant, flame retardant composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-toxic flame-retardant composition containing no halogen atoms and reducing the toxicity of gas generated during combustion as much as possible. The present invention relates to a flame-retardant composition having excellent cold resistance and heat resistance and suitable for covering electric wires or as sheets.

[0002]

2. Description of the Related Art Conventionally, as a flame-retardant electrically insulated wire sheath material, fluorine resin and elastomer, vinyl chloride resin,
Resins such as a non-crosslinked polyolefin composition and a crosslinked ethylene-vinyl acetate resin composition are known. But,
Fluorine resins and elastomers generate a large amount of hydrogen fluoride gas that is harmful to the human body when burned, and therefore have a high toxicity index.In the case of vinyl chloride resins, similar to fluorine resins, combustion of hydrogen chloride gas Not only does it cause adverse effects on the human body, but also corrodes machinery (metal), making it difficult to use. In addition, when trauma resistance, heat resistance and oil resistance are required, a crosslinked elastomer having a higher flexibility and a higher molecular weight is desired as a base resin.

[0003] Crosslinked ethylene-vinyl acetate copolymer resin (EVA) compositions have been proposed as such a crosslinked elastomeric material composition, but for example, have poor cold resistance due to poor embrittlement temperature. Problematic and unsuitable for use in cold climates. Further, non-crosslinked polyolefin sheets containing no halogen are also known, but in particular, heat resistance and oil resistance are inferior, so that their use as sheets is greatly restricted.

Further, there has been proposed a terpolymer obtained by polymerizing ethylene, methyl acrylate and a polymerizable organic carboxylic acid, or a terpolymer obtained by adding a flame retardant such as a metal hydroxide to an acrylic elastomer. . However, simply adding an appropriate amount of carbon or silica fine powder as a reinforcing filler to such a blended system improves all mechanical properties such as tensile strength, elongation, tear strength and hardness. It is impossible to do so, and addition of a large amount of them results in a decrease in the electrical insulation resistance. In the case of silica, the decrease in the insulation resistance particularly upon contact with the steam is remarkable, so that the reinforcing filler is not used. The addition as-is difficult to adopt.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances of the composition for covering or sheathing electric wires, the inventors of the present invention have non-halogen flame retardancy, and have heat resistance, oil resistance and heat resistance. We have been studying to develop an electrical insulation material that has both cold resistance, low toxicity and trauma resistance. Accordingly, an object of the present invention is to provide a heat-resistant and flame-retardant resin composition containing no halogen atom and having the above-mentioned physical properties and useful for covering electric wires.

[0006]

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted many experimental studies on various blended resin compositions, particularly focusing on the base resin, and have found that they have been practically used. Found a highly desirable composition. That is, the present invention provides a heat-resistant and flame-retardant composition having the requirements described in claim 1 of the claims.

The base resin in the flame-retardant composition of the present invention is, in particular, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate and 2
Specific weight of acrylic elastomers selected from elastomers obtained by polymerizing (meth) acrylates such as ethylhexyl (meth) acrylate and ethylene-ethyl acrylate copolymer (EEA) It is constituted by a mixture of ranges. EEA, one of the components constituting the base resin, is a copolymer containing ethylene as a main component, and the ratio of ethylene to ethyl acrylate is, for example, 90 to 60:10. ~ 40 are preferably used. These copolymers may further contain small amounts of other polymerizable monomer components.

E for the above-mentioned acrylic elastomers
Although the addition of EA can provide an addition effect commensurate with the addition amount even in a small amount, a practically desirable mixing ratio is 2% by weight.
0: 1 to 1: 5. The proportion of copolymer added is 2
If the ratio is less than 0: 1, the hardness (tensile strength) of the composition (molded product)
If the mechanical properties such as tearing force are inferior, and the ratio is more than 1: 5, the flexibility (trauma resistance) and oil resistance are inferior, and the flame retardancy is undesirably reduced. A practically desirable mixture weight ratio is 10: 1 to 2: 1.

In consideration of the heat resistance and whitening phenomenon of the molded product, the composition of the present invention has the above-mentioned base resin 10
70 to 150 parts by weight of metal hydroxide is added and blended per 0 parts by weight. The metal hydroxide used in the composition of the present invention includes, for example, aluminum hydroxide, calcium hydroxide, talc and the like, and powdered aluminum hydroxide known as hydrated alumina is preferably used. If the amount of the metal hydroxide is less than 70 parts by weight,
If sufficient flame retardancy cannot be obtained, and if it exceeds 150 parts by weight, not only mechanical properties are deteriorated, but also whitening phenomenon is easily caused at the time of bending, which is not practically preferable. A practically desirable addition amount is 80 to 130 parts by weight.

The composition of the present invention further comprises carbon and / or
Alternatively, powdered silica can be added as a reinforcing filler. These reinforcing fillers are not particularly limited in the shape and size of the particles, but those having a fine and possible spherical shape are preferably used. The addition amount should be 10 to 100 parts by weight of the base resin in consideration of the reinforcing effect and electric insulation.
50 parts by weight are advantageously employed. If the amount of the reinforcing filler is less than 10 parts by weight, a satisfactory reinforcing effect cannot be obtained,
Conversely, if the amount exceeds 50 parts by weight, the electrical insulation properties decrease (in the case of silica-containing materials, they are remarkable after the steam treatment), which is inconvenient. The preferred addition amount is 20 to 40 parts by weight.

When the composition of the present invention is particularly considered to have low smoke emission (low toxicity), red phosphorus and phosphates which generate a large amount of smoke upon combustion are used as flame retardants and plasticizers. It is better to avoid things as much as possible. The composition of the present invention in which EEA is blended with an acrylic elastomer has the advantage of further improving cold resistance. Also,
The flame-retardant composition of the present invention may further contain a small amount of other resins according to the desired coating properties.

[0012]

Next, the features of the present invention will be described in detail with reference to specific examples.

The compositions Formulation Example parts by weight Comparative Example 1 fluorine resin 100 (tetrafluoroethylene-hexafluoropropylene resin) Comparative Example 2 (PVC-based) 100 Yes polyvinyl chloride resin塑agent 50 Filling agent 30 depreciation Filler 4 Comparative Example 3 (Non-crosslinked polyolefin) Ethylene-α-olefin copolymer 100 Metal hydroxide 120 Filler 25 Comparative Example 4 (Crosslinked non-halogen) EVA (VA 28%) 100 Metal hydroxide 120 Filler 60 Bridging agent 3 Crosslinking aid 2 Comparative Example 5 Acrylic elastomer 100 Metal hydroxide 130 Filler 50 Crosslinking agent 3 Crosslinking aid 2

Example (No) 1 2 3 4 5 Acrylic elastomer 95 60 30 60 60 EEA 5 40 70 40 40 Metal hydroxide 130 130 130 100 150 Filler 50 50 50 50 50 Bridge agent 3 3 3 3 3 Crosslinking assistant 2 2 2 2 2

Examples 1 to 5 and Comparative Examples 1 to 5 Various compositions having the above mixing ratios were prepared, and their various properties were measured. However, all the compositions after the composition examples of the above compositions contained 1 part by weight of an antioxidant. In addition, the measuring method of various performances for evaluating each of these compositions and the respective evaluation methods are as follows.

1. Flame retardancy Oxygen index (OI) according to the method specified in JIS K 7201
Measure. {Evaluation}: Displayed as follows depending on the OI value. 40 or more… ◎ 28-40… ○ 28 or less… ×

2. Toxicity Using a test tube of ASTM E 662, the combustion gas during radiant combustion was measured by a detector tube. The toxicity index is calculated from the amount of various harmful gases generated in the combustion gas by the following formula. C ₀ = C × 100 × v / m Toxicity index = ΔC ₀ / Cf where C: concentration of specific gas (ppm) m: weight of combustion sample (g) v: volume of chamber (m ³ ) Cf: each gas Tolerable concentration (ppm) (lethal concentration when a person is exposed to the gas for 30 minutes) The Cf value of the main gas is as follows. CO _2: 10 million in (ppm) CO: 4000 (ppm ) HCl: 500 (ppm) HF: 100 (ppm) { rating}: Display by oxygen index as follows. 5 or more ... × 3 to 5 ... △ 3 or less… ○

3. Trauma resistance JIS K 6301, JIS K 6721 and JIS K
The hardness, tensile strength, and tearing force are measured by the method specified in 6911, etc., and the total is evaluated. Tensile strength (kg / mm ² ) Hardness (Shore) Tear force (kg / mm) {Evaluation} 0.8 or more 80 or more 5.5 or more ○ 0.7 to 0.8 70 to 80 4.5 to 5.5 △ 0.7 or less 70 or less 4.5 or less ×

4. Heat resistance Evaluated by residual elongation (%) after performing a heat aging test at 136 ° C. × 168 hours specified in MIL C 24640. {Evaluation} 70% or more… ○ 60 to 70%… △ 60% or less… × 5. Oil resistance Residual elongation after performing an oil resistance test at 121 ° C. for 18 hours using oil specified in MIL C 24640. Evaluated by percentage (%). {Evaluation} 70-130% ... ○ Others… × 6. Cold resistance Evaluated from the 50% breaking temperature (° C) by an embrittlement test specified in JIS K 6301 and the like. {Evaluation} -35 ° C or less… ○ -35 ° C to -30 ° C… △ -30 ° C or more…
×

The results of each test for each composition are shown in Table 1 below.
It is summarized and shown.

[Table 1]

[0021]

As is clear from the above table, the composition (molded product) of the present invention has the following excellent effects. 1) By blending EEA with acrylic elastomer, mechanical properties and cold resistance are improved. 2) Because it is a non-halogen composition, it does not generate hydrogen halide gas harmful to the human body and has low toxicity. 3) Elastomer type, excellent in scratch resistance and oil resistance. 4) Since the acrylic elastomer itself has excellent heat resistance, the composition has extremely high heat resistance. 5) Excellent flame retardancy and low fire spread. 6) It has an improved embrittlement temperature (about -35 ° C) compared to the embrittlement temperature (about -20 ° C) of EVA elastomer and the like, and has extremely excellent cold resistance. 7) Low smoke emission.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akira Yoshino 9-1 Futaba-cho, Numazu-shi, Shizuoka Prefecture Fujikura Numazu Plant (72) Inventor Motohisa Murayama 1-1-1, Kiba, Koto-ku, Tokyo Stock Company In Fujikura (56) References JP-A-64-79262 (JP, A) JP-A-62-4734 (JP, A) JP-A-59-500816 (JP, A) (58) Fields investigated (Int. . ^6, DB name) C08L 33/06 - 33 / 12,23 / 08 C08K 3/22 H01B 3/44

Claims (1)

(57) [Claims] 1. Methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate and 2.
20: 1 to 1: 5 of an acrylic elastomer selected from elastomers obtained by polymerizing acrylic esters such as ethylhexyl (meth) acrylate and an ethylene-ethyl acrylate copolymer. A heat resistance obtained by mixing 70 to 150 parts by weight of a metal hydroxide with respect to 100 parts by weight of the base resin in a mixed base resin in a weight ratio;
Flame retardant composition.