JPH02258857A - Flame-retardant mixture - Google Patents

Abstract

PURPOSE:To obtain a flame-retardant mixture resistant to discoloration with sulfur independent of the laid environment and capable of imparting high flame- retardancy with a small amount of the retardant by compounding a polyvinyl chloride with diantimony tetroxide or diantimony pentoxide. CONSTITUTION:The objective mixture is produced by compounding 100 pts.wt. of a polyvinyl chloride with 1-30 pts.wt. of diantimony tetroxide and/or diantimony pentoxide and further 1-30 pts.wt. of an alkaline-earth metal oxide and/or alkaline-earth metal hydroxide. The polyvinyl chloride is preferably the one having a polymerization degree of especially 1,000-2,000 or thereabout and containing zinc stearate, calcium stearate, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a flame-retardant mixture suitably used as a sheath material, a semiconducting layer, an insulating layer, etc. for electric wires, cables, etc.

"Prior Art" Conventionally, when polyvinyl chloride mixtures are used as sheathing materials for electric wires and cables, various flame retardants have been added to polyvinyl chloride when high flame retardancy is required. A method is being implemented.

The commonly known flame retardants include:
Examples include inorganic flame retardants such as aluminum hydroxide or magnesium hydroxide, or diantimony trioxide.

However, in order to obtain sufficient flame retardancy as a sheath material for electric wires, cables, etc. using inorganic flame retardants such as aluminum hydroxide, a large amount of flame retardant is required, and the mechanical properties of the sheath material are affected. There was a problem of lowering extrusion processability.

In contrast, the above-mentioned diantimony trioxide has been widely used in sheath materials for electric wires, cables, etc., as it can provide high flame retardancy with a small amount of addition.

``Problems to be Solved by the Invention'' However, when a polyvinyl chloride mixture containing the above-mentioned diantimony dioxide as a flame retardant is used as a sheath material for electric wires, cables, etc., depending on the installation environment of the electric wires, cables, etc. In many cases, the sheath material became discolored. Specifically, this phenomenon was observed in environments containing sulfur ions, such as hot springs and oil plants. That is, sulfur discoloration occurs due to the reaction between sulfur ions contained in the atmosphere and diantimony trioxide to produce antimony sulfide.

Therefore, the present invention aims to solve the above-mentioned problems and provide a flame-retardant mixture that does not undergo sulfurization and discoloration regardless of the installation environment and exhibits high flame retardancy with the addition of a small amount of flame retardant.

"Means for Solving the Problem" The present invention provides a solution by adding 1 to 30 parts by weight of diantimony tetroxide and/or diantimony pentoxide to 100 parts by weight of polyvinyl chloride.

The present invention will be explained in detail below.

The flame retardant mixture of the present invention differs from conventional flame retardant mixtures mainly because it contains either or both of diantimony tetroxide and diantimony pentoxide as a flame retardant. This is because they are mixed together.

Therefore, this flame retardant mixture does not discolor even in an environment containing sulfur ions, and has the effect of being able to obtain high flame retardancy with the addition of a small amount of flame retardant.

Here, the above-mentioned diantimony tetroxide and diantimony pentoxide are compounds that have the property of being difficult to react with sulfur to produce antimony sulfide that causes sulfur discoloration, and their crystalline form is crystalline even if it is anhydrous. There is no problem even if it contains water. Further, either diantimony tetroxide or diantimony pentoxide may be used, but a combination of both is also possible. It is also possible to use it in combination with diantimony trioxide, which has been conventionally used as a flame retardant, but in order to obtain a higher sulfurization discoloration inhibiting effect, it is preferable to avoid using diantimony trioxide.

Here, the amount of diantimony tetroxide and/or diantimony pentoxide added is limited to the above range because sufficient flame retardancy can be obtained when the amount is less than 1 part by weight based on 100 parts by weight of polyvinyl chloride. Moreover, if the amount exceeds 30 parts by weight, extrusion processability and mechanical properties may deteriorate.

Normal polyvinyl chloride is used as the base resin in which these flame retardants are blended, but in particular polyvinyl chloride with a polymerization degree of 1000 to 2
000 is preferably used.

It is also preferred that a polyvinyl chloride stabilizer is added to the flame retardant mixture. This stabilizer is
Inorganic salts, metal fatty acid salts, organic tin compounds, epoxy compounds, etc. are used, and metal fatty acid salt-based stabilizers are particularly preferably used because they are highly effective in improving thermal stability. As the metal fatty acid salt stabilizer, fatty acid salts of metals such as zinc, barium, calcium, cadmium, tin, etc. are used alone or as a mixture. Specifically, for example, zinc stearate, calcium stearate, barium stearate, etc. are preferably used.

Furthermore, in addition to these, plasticizers, anti-aging agents, antioxidants, lubricants, ultraviolet absorbers, pigments, etc. may be added as appropriate.

Next, the flame retardant mixture according to claim 2 is composed of polyvinyl chloride 10
0 parts by weight, 1 to 30 parts by weight of diantimony tetroxide and/or diantimony pentoxide, and 1 to 30 parts by weight of an alkaline earth metal oxide or alkaline earth metal hydroxide. be.

By the way, the above-mentioned flame retardants diantimony tetroxide and diantimony pentoxide are strongly acidic and have the property of acting as an inorganic ion exchanger in a mixture and easily reacting with other metals. Therefore, by making the above-mentioned basic alkaline earth compound exist in the mixture,
The antimony compound mentioned above tends to selectively react with this alkaline earth compound. Therefore, no reaction occurs with the stabilizer contained in this mixture.

That is, the advantage is obtained that the stabilizer can act reliably and the thermal stability of this flame-retardant mixture is ensured.

Here, the above alkaline earth metals include magnesium,
Calcium, barium, etc. are used, but in order to prevent moisture absorption of these oxides or hydroxides, those that have been surface-treated with stearic acid or the like are preferably used.

The reason why the amount of the alkaline earth metal compound added is limited to the above range is because if it is less than 1 part by weight based on 100 parts by weight of polyvinyl chloride, thermal stability cannot be maintained. This is because if the amount exceeds 100%, mechanical properties and extrusion processability may deteriorate.

Such a flame-retardant mixture is obtained by mixing predetermined amounts of each of the above-mentioned compounds, and then kneading the mixture using a conventional Panbury mixer, roll blender, or the like. This flame-retardant mixture is molded into a film, sheet, or vibrator using a molding machine such as an extruder or an injection molding machine, and then used.

The applications are wide-ranging, such as jackets, sheaths, semiconducting layers, insulating layers, and intervening bodies for various electric wires and cables.

Since such flame retardant mixtures contain diantimony tetroxide and/or diantimony pentoxide as flame retardants, they exhibit high flame retardancy even with the use of a small amount of flame retardant. Even in environments containing sulfur, such as hot springs, it does not react with sulfur to produce antimony sulfide, and therefore has the effect of preventing sulfur discoloration.

Furthermore, in the flame-retardant mixture described in item 2, since the flame-retardant mixture contains alkaline earth metal oxides and/or hydroxides, the antimony compound and the mixture contain alkaline earth metal oxides and/or hydroxides. Since the reaction with the stabilizer is suppressed, the thermal stability of this flame-retardant mixture can be maintained.

"Example" Flame retardant mixtures of Examples (6 examples) of the present invention and Comparative Example (1 example) were prepared according to the blending amounts shown in Table 1.

Table 1 The samples were immersed for 1 hour at a temperature of 25°C, and discoloration due to sulfurization was observed.

In addition, thermal stability was investigated by heating in an oven at a temperature of 290°C. These results are summarized in Table 2.

Here, polyvinyl chloride has a degree of polymerization of 1 to.

A barium-zinc fatty acid salt stabilizer was used as the stabilizer. A phthalate ester plasticizer (DOP) was also used.

Next, using the flame retardant mixtures of these Examples (6 Examples) and Comparative Example (1 Example), the oxygen index (0, J,) was measured in accordance with JIS-7201. was used as a measure of flame retardancy. In addition, these flame retardant mixtures were added at a concentration of 20 ppm.
As is clear from the results in Table 2, the flame-retardant mixtures of the examples of the present invention do not discolor due to sulfurization even in the presence of sulfur ions, and have high flame retardancy. I found out that In comparison, sulfur discoloration was observed in conventional flame retardant mixtures using only diantimony trioxide as a flame retardant. In addition, flame-retardant mixtures containing alkaline earth metal oxides or hydroxides (Examples 2 to 6) have higher thermal stability than those that do not contain alkaline earth metal oxides or hydroxides (Example I). It turned out to be excellent.

"Effects of the Invention" As explained above, the flame-retardant mixture of the present invention is obtained by adding 1 to 30 parts by weight of diantimony tetroxide and/or diantimony pentoxide to 100 parts by weight of polyvinyl chloride. Therefore, even in an environment where sulfur ions are present, there is no sulfurization and discoloration, and high flame retardancy can be obtained with the addition of a small amount of flame retardant.

Moreover, in the flame-retardant mixture of claim 2, since an oxide and/or hydroxide of an alkaline earth metal is used in combination, good thermal stability can be ensured. Therefore, there is an advantage that deterioration in extrusion processability, mechanical properties, etc. due to thermal deterioration during heat processing can be prevented or suppressed.

Claims (2)

[Claims] (1) A flame-retardant mixture prepared by adding 1 to 30 parts by weight of diantimony tetroxide and/or diantimony pentoxide to 100 parts by weight of polyvinyl chloride. (2) 100 parts by weight of polyvinyl chloride, 1 to 30 parts by weight of diantimony tetroxide and/or diantimony pentoxide, and 1 to 30 parts by weight of alkaline earth metal oxide and/or alkaline earth metal hydroxide. Flame retardant mixture with added.