JPS61276859A - Method for mixing flame-retardant composition - Google Patents

Abstract

PURPOSE:To avoid the ignition of red phosphorus in kneading and mixing and improve the operability, by kneading a copolymer resin or rubber with red phosphorus premixed with aluminum hydroxide and further a hydrated inorganic material. CONSTITUTION:100pts.wt. copolymer resin or rubber consisting essentially of ethylene and containing no halogen is kneaded and mixed with a mixture of powder consisting essentially of aluminum hydroxide (containing 2-30pts.wt. red phosphorus) to give <=60wt% red phosphorus and 50-150pts.wt. hydrated inorganic material containing the above-mentioned aluminum hydroxide. Polyethylene, ethylene-propylene rubber, etc., may be used as the resin or rubber. Magnesium hydroxide is preferred for the hydrated inorganic material.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of mixing a flame-retardant composition suitable as a material for, for example, flame-retardant electric wires, cable insulators, and sheaths.

(Prior Art) Flame retardation of conventional polyolefin resins and rubbers as flame retardant compositions is often achieved by using a combination of a halogen-containing flame retardant and antimony dioxide. However, although such a composition exhibits a high degree of flame retardancy because it contains halogen, it generates a large amount of smoke when burned, which is a problem.

It is known to add a large amount of a hydrated inorganic compound such as aluminum hydroxide to a polyolefin resin or rubber to create a composition that generates less smoke during combustion. Although this composition produces less smoke than a composition that uses a halogen-containing flame retardant and antimony trioxide in combination, it does not have satisfactory flame retardancy and has not been put to practical use.

Also known is a composition in which a polyolefin resin or rubber is combined with a hydrated inorganic compound and red phosphorus as a composition with good flame retardancy and low smoke emission.

(Problems to be Solved by the Invention) This composition had a problem during kneading and mixing due to the risk of red phosphorus igniting.

For this reason, the surface of red phosphorus is coated with resin or inorganic material to lower the ignition temperature to 2.
Surface-treated red phosphorus with a temperature improvement of 50-100°C from 50°C to 300-350°C is also known, but it is not as good as ζ.

In view of the above, the present invention has been developed to solve these problems. The present invention will be explained in detail below.

The method of mixing the flame retardant composition of the present invention is to mix hydrated inorganic material and red phosphorus with a halogen-free copolymer resin or rubber mainly composed of ethylene, and then mix red phosphorus with hydroxide in advance as red phosphorus. It is characterized in that it uses a mixture of powder mainly composed of aluminum and that the amount of red phosphorus in the mixture is 60% by weight or less.

(Function) By mixing red phosphorus and aluminum hydroxide, no ignition of red phosphorus is observed during mixing, improving workability.

The above will be explained below.

Halogen-free copolymer resins mainly composed of ethylene or rubber include polyethylene, ethylene-
Examples include vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene propylene rubber.

Examples of the hydrated inorganic substance include aluminum hydroxide, magnesium hydroxide, etc., but magnesium hydroxide is preferable because it does not cause material to drip during combustion.

By mixing red phosphorus and aluminum hydroxide, the ignition temperature is greatly increased. When red phosphorus exceeds 60 weight percent, the ignition temperature decreases.

In order to obtain high flame retardancy, the amount of each material added is 1:1 of ethylene-based halogen-free copolymer resin or rubber.
00 parts by weight, 50 to 150 parts by weight of hydrated inorganic matter, and 2 to 150 parts by weight of red phosphorus.
60 parts by weight is preferred. If it is less than this, sufficient flame retardancy will not be obtained, and if it is more than this, the mechanical properties will not be sufficient. The kneading and mixing methods include open roll, Banbury mixer,
Examples include a twin-screw press ratio machine.

(Example) Examples will be described below to help understand the present invention.

The relationship between the content of red phosphorus and aluminum hydroxide and ignition is as follows:
It was as shown in Table 1.

In addition, as a result of measuring the ignition temperature of Comparative Example 1 and Example 1, it was 250°C in Comparative Example 1, but 400°C in Example 1.
That was it.

Table 1 Ignition Temperature (Note) Test Method Place 1 g of sample in an iron bowl and hold a 3 Kf iron ball at a height of 50 (7
) to see if there was any ignition or not.

(Effect of the invention) As described above, the present invention has the following effects.

Since red phosphorus is mixed with aluminum hydroxide in advance, there is no need to worry about fire.

Claims (4)

[Claims] (1) When kneading and mixing a hydrated inorganic substance and red phosphorus into a halogen-free copolymer resin or rubber mainly composed of ethylene, add aluminum hydroxide to the red phosphorus in advance so that the red phosphorus content is 60% by weight or less. A flame retardant composition characterized in that the mixture of red phosphorus and powder mainly composed of red phosphorus and aluminum hydroxide and the above hydrated inorganic substance are kneaded and mixed with the above resin or rubber. How to mix things. (2) A hydrated inorganic substance containing aluminum hydroxide mixed in advance with 100 parts by weight of ethylene-based halogen-free copolymer resin or rubber with red phosphorus 50 to 1
50 parts by weight of red phosphorus and 2 to 30 parts by weight of red phosphorus. (3) A method for mixing a flame retardant composition according to claim (1), wherein the kneading and mixing is performed using a Banbury mixer. (4) The method for mixing a nonflammable composition according to claim (1), wherein the hydrated inorganic substance is magnesium hydroxide.