KR0124033B1 - Wire insulating thermosetting resin composition - Google Patents

Abstract

A flame resistant electric wire-covering materal compsn. comprises(i) 100 pts. wt.of the basic resin mixture of vinylacetate copolymer(a) having a content of vinylacetate residue of 20-30 wt% with a vinylacetate copolymer(b) having a content of vinylacetate residue of 70 wt. % in a wt. ratio of a/b of 3:7-6:4 (ii) 3-10 wt. % of an organic peroxide such as dicumylperoxide, benzoylperoxide (iii) 20-80 wt. % of magnesiumhydroxide as a flame retardant and a filler (iv) an antioxidant, stabiliser, curing agent, surfactant, plasticiser etc. if necessary. The flame retardant compsn. generates no hydrogen halide gas during combustion and has a good teminal processability and uses as a sheathing materal for electric wire and cable.

Description

Thermosetting resin composition for electric wire coating

The present invention relates to a thermosetting resin composition for electric wire coating having excellent flame retardancy and weather resistance, and more particularly, to prevent the propagation of sparks through a power source in the event of a fire, to minimize the generation of smoke, and to minimize the generation of toxic gases such as halogen gas. The present invention relates to a thermosetting resin composition for electric wire coating which suppresses and maintains a certain level of mechanical strength and weather resistance while maintaining the ability to conduct electricity for a predetermined time even when a fire occurs.

Such flame retardant non-toxic and low-flame fire-resistant wires have no escape routes (fire, maritime buildings, coal mines, etc.) in the event of a fire in order to minimize human injury in the event of a fire, or they cannot escape immediately (hospital, large and high-rise buildings). Etc.), must be used for some time even after a fire (spring cooler, emergency power supply, etc.) and other vehicles.

Conventional wires for construction having only fire resistance and flame resistance, and a resin composition having a relatively low flame retardancy and low non-toxicity and low flame retardancy has been studied a lot, but at the same time satisfying the above flame retardancy, fire resistance, non-toxicity and low flame retardancy more than a certain level The research on the resin composition which can be used in such harsh environmental conditions is hardly done.

That is, in order to suppress the generation of toxic gas, there is an example of using inorganic fillers in which one or two inorganic flame retardants are mainly mixed with aluminum hydroxide or magnesium hydroxide in place of halogen flame retardants, but when these inorganic flame retardant fillers are used, Although there is some effect on the low inhibition, there have been disadvantages in that it does not satisfy other requirements such as low ductility, fire resistance, and weather resistance at the same time.

In addition, when the inorganic flame retardant filler is used to improve the flame retardancy, the composition composed of the polymer resin and the inorganic filler generally has a lower mechanical strength in proportion to the content of the inorganic filler, which is caused by poor dispersibility of the inorganic filler. .

In order to increase the dispersibility of such inorganic fillers, low molecular weight waxes or stearic acid may be used, but the dispersibility of the inorganic fillers is increased when they are used. This results in a decrease in mechanical strength and weather resistance.

In order to make up for these drawbacks, olefinic crystalline polymer resins having excellent mechanical strength are often mixed. This method can temporarily improve the mechanical strength of the compound, but prevents cracking due to phase separation between components due to prolonged use. The disadvantage is that you can't.

Accordingly, an object of the present invention is to provide a flame retardant electric wire coating resin composition having a degree of weatherability and mechanical strength that can be used even in harsh environmental conditions such as an offshore structure.

In order to solve the above problems, the inventors of the present invention is a mixture of ethylene-vinylacetate copolymer (EVA) base resin and a flame retardant filler to impart flame retardancy, low flammability, low inhibition and fire resistance, When a low content of ethylene-vinylacetate copolymer and a high content of vinyl acetate are blended with an organic peroxide crosslinking agent, the crosslinking agent makes the resin composition thermosetting, and thus the weatherability (heat aging, Ethylene-vinylacetate copolymer with excellent oil resistance and high vinyl acetate content disperses the flame retardant, eliminating the possibility of phase separation and also prevents excessive hardening due to the addition of crosslinking agent. Flame retardant wires that can be used even under conditions It is aware of the fact that the clothing will be able to provide to the completion of the present invention.

Therefore, according to the present invention, a vinyl acetate content of 20 to 30% by weight of ethylene vinyl acetate copolymer (hereinafter referred to as EVA-1) versus vinyl acetate content of 70% by weight of ethylene vinyl acetate copolymer (hereinafter referred to as EVA-2) 3: 3 to 10 parts by weight of an organic peroxide crosslinking agent, 20 to 80 parts by weight of magnesium hydroxide, and 20 to 80 parts by weight of magnesium calcium carbonate as a flame retardant, based on 100 parts by weight of a 3: 7 to 6: 4 mixture A coating thermosetting resin composition is provided.

Hereinafter, the present invention will be described in more detail.

According to the present invention two kinds of ethylene-vinylacetate copolymers are used. One of them is EVA-1, with a vinyl acetate content of 20-30% by weight, and the other is EVA-2, with a vinyl acetate content of 70% by weight.

The ratio of EVA-1 to EVA-2 in this composition has a preferable ratio of 3: 7-6: 4. If the ratio of EVA-1 is less than 3 steps and the ratio of EVA-2 is greater than 7, the crosslinking is insufficient, resulting in poor weather resistance, and the ratio of EVA-1 is greater than 6, that is, the ratio of EVA-2 is less than 4. If not, flexibility and elasticity are poor.

In the present invention, in order to enhance weather resistance (heat aging and oil resistance) and to reinforce physical properties, the ethylene-vinylacetate copolymer is crosslinked, and a crosslinking agent is blended for this purpose.

As the organic peroxide crosslinking agent, dicumyl peroxide, benzoyl peroxide alone or a mixture thereof may be used.

3-10 weight part of organic peroxide type crosslinking agents are preferable with respect to 100 weight part of EVA. If the content is less than 3 parts by weight, the crosslinking effect is insignificant. If the content is more than 10 parts by weight, the crosslinking is too much, and the stiffness of the wire is too high, which increases the possibility of microcracking in the wire.

As the inorganic flame retardant filler in the composition, magnesium hydroxide and magnesium calcium carbonate hydrate are preferable, and the preferred content thereof is in the range of 20 to 80 parts by weight based on 100 parts by weight of the total amount of ethylene-vinylacetate copolymer. If magnesium hydroxide is less than 20 parts by weight, the flame retardant effect is inferior, and if it exceeds 80 parts by weight, mechanical properties and workability is greatly reduced. The same also applies to magnesium calcium carbonate hydrate.

Magnesium calcium carbonate hydrates include huntite (Mg ₃ Ca (CO ₃ ) ₄ ) and hydromagnesite (Mg ₄ (CO ₃ ) ₃ · (OH) ₂ · 3H ₂ O Mg ₃ (CO ₃ ) ₄ · ( Inorganic flame retardant filler with the same amount of OH) ₂ · 4H ₂ O) mixed, which is much higher than aluminum hydroxide, which has been used in the prior art.

In the present composition, antioxidants, reinforcing agents, flame retardant aids, processing aids, dispersion accelerators, pigments, emulsifiers, surfactants, and the like may be added in addition to the above components.

Although not particularly limited, the antioxidant may be used in combination of a primary antioxidant and a secondary antioxidant, the content of which is preferably 5 parts by weight or less based on 100 parts by weight of the total amount of the ethylene-vinylacetate copolymer. If more than 5 parts by weight of antioxidant is used, the performance of the crosslinking agent may be deteriorated and the degree of crosslinking may be lowered. Titanium dioxide (TiO ₂ ) and silica (SiO ₂ ) can be used as a reinforcing agent to reinforce the deterioration of mechanical properties, and the preferable content thereof is 10 to 30 parts by weight based on 100 parts by weight of the total amount of ethylene-vinylacetate copolymer. to be. If the reinforcing agent is used in less than 10 parts by weight, the reinforcing effect is insignificant, and when used in excess of 30 parts by weight, it is possible to promote the lowering of mechanical properties, in particular elongation. As a flame retardant adjuvant, antimony trioxide, zinc borate, a tricrosol phosphate, etc. can be used, The preferable content is 5-15 weight part with respect to 100 weight part of total amounts of an ethylene-vinylacetate copolymer. If the flame retardant aid is used less than 5 parts by weight, the effect is insignificant, and when used in excess of 15 parts by weight, a problem arises that the toxicity index increases. Wax and mineral oil etc. can be used as a processing aid, The preferable content is 5-15 weight part with respect to 100 weight part of ethylene-vinylacetate copolymer total amounts. If the amount of the processing aid is less than 5 parts by weight, the effect as a processing aid is insignificant. If the amount is more than 15 parts by weight, the mechanical properties, in particular, the tensile strength is accelerated.

Features of the present invention as described above and other features will become more apparent from the description of the non-limiting examples described below.

EXAMPLES 1-4

In the composition shown in Table 1, each component except the crosslinking agent was used in a kneader, and then again kneaded, followed by a second kneading operation, followed by final mixing and dispersion, followed by adding and dispersing the crosslinking agent in a mill, and pellets through the next extruder. After the preparation was made, it was crosslinked by heat press.

Oxygen index, smoke density, toxicity index, tensile strength (kgf / mm ² ), elongation (%), tensile strength residual ratio (%) after heating aging, elongation residual ratio (%) after heating aging, after oil test The properties were evaluated by measuring the tensile strength residual ratio (%) and the elongation residual ratio (%) after the oil resistance test.

Among the characteristics of each sample, heating aging was measured by accelerated aging of 135 ℃ × 168 hours applied to marine jacket materials and 100 ℃ × 48 hours of oil resistance, and the Oxygen Index was ASTM D 2683, Smoke density. 6mm sheet was used as Flaming Mode of ASTM E 662, and the Toxicity Index was evaluated according to NES 713. The evaluation results are shown in Table 2 below.

As can be seen from Tables 2 and 3, the whole body coatings of Examples 1-4 according to the present invention exhibit excellent properties even in harsh environmental conditions. On the other hand, as the EVA-1 content increased in Example 1-4, the tensile strength increased, the elongation decreased slightly, and the smoke density increased, but the oxygen index and the toxicity index remained almost unchanged. There is little change, but oil resistance is slightly reduced.

EXAMPLES 5-8

The same procedure as in Example 1 was repeated except that the composition of Table 3 was used. The characteristics of the resulting output are shown in Table 4 below.

[Comparative Examples 1-3]

The same procedure as in Example 1 was repeated except that the composition of Table 5 was used. The properties of the resulting output are shown in Table 6 below.

As can be seen from Tables 4 and 6, the use of aluminum hydroxide as a flame retardant filler has a very high smoke density and toxicity index, and the use of magnesium hydroxide alone lowers the smoke density and toxicity index. However, as shown in Comparative Example 3, it can be seen that the smoke density and the toxicity index are increased again when aluminum hydroxide is used.

On the other hand, when using a mixture of magnesium hydroxide and magnesium carbonate calcium hydrate as in Examples 5 to 8 it can be seen that the smoke density and toxicity index is lowered again and has a good tensile strength. In particular, as the ratio of magnesium calcium carbonate increases, smoke density and toxicity index decrease. In the case of the elongation rate, it can be seen that the magnesium hydroxide and magnesium carbonate calcium hydrate are higher than when the aluminum hydroxide is used. Weathering (heat aging and oil resistance) properties did not exert a significant effect when mixing the same amount of flame retardant filler. From the above results, it can be seen that in order to satisfy flame retardancy, low flammability and non-toxicity simultaneously, a large amount of magnesium calcium carbonate hydrate should be used rather than aluminum hydroxide.

Claims (1)

3 to 10 parts by weight of an organic peroxide-based crosslinking agent based on 100 parts by weight of a 3: 7 to 6: 4 mixture of a vinyl acetate content of 20 to 30% by weight of ethylene vinyl acetate copolymer to a vinyl acetate content of 70% by weight of ethylene vinylacetate copolymer And 20 to 80 parts by weight of magnesium hydroxide and 20 to 80 parts by weight of magnesium calcium carbonate hydrate as a flame retardant filler.