JPS5929048B2 - Method for producing photo-stable brominated diphenyl ether - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing photo-stable brominated diphenyl ethers.

川BrBrBrBrBr B卦onowBrh The present inventors have discovered that this weak C-Br bond has been chemically (recently, in Japan and other countries, the flame retardant of plastics has been
There is a trend toward stricter regulations, and studies are progressing on the manufacturing methods and application methods of various flame retardants.

It is already known that decabromidiphenyl ether and brominated diphenyl ethers mainly composed of decabromidiphenyl ether are very effective as flame retardants for various plastics, especially for polyolefins such as polystyrene, polypropylene, It is an extremely useful flame retardant for making polyethylene flame retardant. Although the mechanical properties, thermal stability, and flame retardance of plastics made flame-retardant with decabromodiphenyl ether and brominated diphenyl ether, which is mainly composed of decabromodiphenyl ether, are extremely good, the biggest drawback is that it is easily exposed to light. The plasti changes color, and as the color change progresses, the physical properties of the resin gradually deteriorate, that is, the weather resistance deteriorates.

As a result of many years of detailed study on the deterioration mechanism of plastics made flame retardant by decabromodiphenyl ether and brominated diphenyl ether containing decabromodiphenyl ether as the main component, the present inventors have developed the following formula as an example. As shown, some of the C-Br bonds in the bromine bonded to the benzene ring of decabromodiphenyl ether are very weak and are easily decomposed by light, especially ultraviolet light, to form carbon radicals and bromine radicals. It has been found that radicals attack the resin and promote its deterioration. Based on the idea that by removing the bromine, a brominated diphenyl ether that is stable against light without reducing its fire resistance can be obtained.As a result of various studies, we found a reaction that allows easy exchange with bromine. The present inventors have discovered that a photo-stable brominated diphenyl ether can be obtained by heating in an organic solvent containing highly reactive hydrogen, leading to the completion of the present invention.

Accordingly, the present invention provides a light-stable product which is characterized by heating a brominated diphenyl ether containing decaprom diphenyl ether as a main component for a certain period of time in an organic solvent containing hydrogen that can be exchanged with bromine under the reaction conditions. The present invention relates to a method for producing brominated diphenyl ether. It has not yet been determined with certainty which bromine position in decabromodiphenyl ether undergoes an exchange reaction with hydrogen in the organic solvent by the method of the present invention, but it is presumed to be the bromine at the ortho position.

The brominated diphenyl ether containing decaprom diphenyl ether as a main component, which is a raw material for the process of the present invention, can be obtained by brominating diphenyl ether with bromine in a commonly known manner. The method of the present invention involves dissolving the bromination reaction product of diphenyl ether in an organic solvent containing highly reactive hydrogen that can be easily exchanged with bromine under normal or elevated pressure, or finely pulverizing the product and then suspending the product. The purpose is to obtain a light-stable brominated diphenyl ether by making it cloudy and heating it to 80 to 250°C for a certain period of time (usually 1 to 10 hours). Examples of organic solvents containing hydrogen that can be exchanged with bromine under the reaction conditions used in the present invention include methyl iodide, ethyl bromide, -n-propyl chloride, allyl bromide, methylene bromide, chloroform, ethylene dichloride, and tetrachloride. chloroethane, etc., logenated aliphatic hydrocarbons, acetic acid, propionic acid, caproic acid, acrylic acid, and other carboxylic acids,
Preferred are ketones such as acetone, methyl ethyl ketone, diethyl ketone, and hexanone, and alkylbenzenes such as benzene, toluene, and xylene.

Usually, it is preferable to use 10 to 100 parts by weight of these solvents per 1 part by weight of the brominated diphenyl ether as a raw material.

The reaction time varies depending on the reactivity of the organic solvent used and the heating temperature, but may be heated for 1 to 10 hours.

The brominated diphenyl ether thus obtained can be
It is a compound that is particularly stable against ultraviolet rays, and when blended as a flame retardant with plastics, especially polyolefins such as polystyrene, polypropylene, and polyethylene, it is significantly more effective than plastics containing brominated diphenyl ether simply recrystallized in an organic solvent. It was found to exhibit excellent weather resistance. This will be explained below using an example.

Example 1 100 parts by weight of crude decaprom diphenyl ether obtained by brominating diphenyl ether with bromine was added to 2000 parts by weight of m-xylene, heated to 130°C to dissolve, and stirred at that temperature for 5 hours. continued.

After cooling, the obtained crystals were separated and dried to obtain 90 parts by weight of brominated diphenyl ether. Analysis value C: 17.1
% Br: 80.8% Average composition Cl2Hl・5Br8
-50 Example 2 100 parts by weight of crude decaprom diphenyl ether obtained by brominating diphenyl ether with bromine was mixed with 200 parts by weight of acetone.
0 parts by weight, heated to 100° C. under pressure, and continued stirring for 10 hours.

After cooling, the obtained crystals were dried separately to obtain 93 parts by weight of brominated diphenyl ether. Analysis value C: 16.4%
Br: 82.0% Average composition Cl, HlBr, O Example 3 100 parts by weight of crude decaprom diphenyl ether obtained by brominating diphenyl ether with bromine was mixed with 300 parts by weight of acetic acid.
0 parts by weight, and heat-treated at 120° C. for 7 hours.

After cooling, the obtained crystals were filtered, washed with methanol, and dried to obtain 94 parts by weight of brominated diphenyl ether. Analysis value C: 16.4% Br: 81.9% Average composition C
12HlBr9O Example 4 100 parts by weight of crude decaprom diphenyl ether obtained by brominating diphenyl ether with bromine was added to 1000 parts by weight of methylene bromide, and heat treated at 100°C for 3 hours.

After cooling, the obtained crystals were filtered and dried to obtain 86 parts by weight of brominated diphenyl ether. Analysis value C: 18.0%
Br: 79.8% Average composition Cl2H2Br8O Reference example Brominated diphenyl ether obtained by recrystallizing 100 parts of styrene resin from an organic solvent, or brominated diphenyl ether obtained by heating reaction in an organic solvent according to the above example. Add 15 parts each of enyl ether, and a small amount of ultraviolet absorber,
A heat stabilizer and the like are added, and the mixture is thoroughly kneaded and molded at a temperature of 240°C or lower.

Claims (1)

[Claims] 1. A method for producing light-stable brominated diphenyl ether, which comprises heating brominated diphenyl ether containing decabromodiphenyl ether as a main component in an organic solvent containing hydrogen that can be exchanged with bromine under reaction conditions.