JPS5913483B2 - Method for producing photo-stable brominated diphenyl ether - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a process for producing light-stable brominated diphenyl ethers useful as flame retardants for plastics, particularly polyolefin resins.

*BrBrBrBrBr Br□o□B -black-→ 1 BrBrBrBrBr The present inventors chemically strengthened this weak C-Br bond.*Recently, in Japan and other countries, regulations regarding flame retardancy of plastics are becoming stricter. , and studies are progressing on the manufacturing and application methods of various flame retardants.

Decabromidiphenyl ether and brominated diphenyl ether, which has decabromidiphenyl ether as its main component, are already known to be very effective as flame retardants for various plastics, especially for polyolefins such as polystyrene, polypropylene, polyethylene, etc. 10 It is an extremely useful flame retardant for flame retardation.
The mechanical properties, thermal stability, and flame retardance of plastics made flame-retardant with decabromidiphenyl ether and brominated diphenyl ether, which is mainly composed of decabromidiphenyl ether, are excellent15, but the biggest drawback is that they cannot be easily exposed to light. As the color changes, the plastic changes color, and as the color change progresses, the physical properties of the resin gradually deteriorate, that is, the weather resistance deteriorates. The present inventors have been developing decabrominated diphenyl ether and brominated di-20 containing it as a main component for many years.
As a result of a detailed study on the photodegradation mechanism of plastics made flame retardant with phenyl ether, we found that some of the bromine bonded to the benzene ring of decabromidiphenyl ether, as shown in formula (I) below, is an example. C
-Br bond is very weak and is easily decomposed by light, especially ultraviolet light, and becomes carbon radicals and bromine radicals.
It has been found that these radicals attack the resin and accelerate its deterioration. By removing 1 to 3 bromines by BrBr-Br □□ ... BrBrBrBr or by physically cutting, a brominated diphenyl ether that is stable against light without reducing flame retardancy can be obtained. As a result of various studies based on the idea that bromine can be obtained, it has been found that photo-stable bromine can be obtained by reacting it in the presence of a reducing sulfur compound in an organic solvent containing active hydrogen that can easily react with bromine. The present invention was achieved by discovering that diphenyl ether can be obtained.

Accordingly, the present invention provides decaprom diphenyl ether and brominated diphenyl ether containing decaprom diphenyl ether as a main component in the presence of a sulfur compound having reducing properties in an organic solvent having hydrogen that can be exchanged with bromine under reaction conditions. The present invention relates to a method for producing photo-stable brominated diphenyl ether, which is characterized by a reaction. It has not yet been determined with certainty which bromine position in decaprom diphenyl ether undergoes the 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 by a commonly known method. In the method of the present invention, the bromination reaction product of diphenyl ether is dissolved or suspended in an organic solvent having active hydrogen that can be easily exchanged with bromine at room temperature or with heating, and then The purpose is to obtain a brominated diphenyl ether that is stable to light by adding a sulfur compound having reducing properties and reacting for a certain period of time, usually 30 minutes to 10 hours, followed by recrystallization if necessary. Examples of organic solvents having hydrogen exchangeable with bromine under the reaction conditions of the present invention include alkylbenzenes such as benzene, toluene and xylene, ketones such as acetone, methyl ethyl ketone, diethyl ketone and hexanone, acetic acid, propionic acid, and capron. Acids and carboxylic acids such as acrylic acid are effective.

Usually these organic solvents are brominated diphenyl ether 1
It is preferable to use 10 to 100 parts by weight. Sulfur compounds with reducing properties used in the present invention include hydrogen sulfide, hydrogen sulfide such as sodium hydrogen sulfide, potassium hydrogen sulfide, sulfides such as sodium sulfide and potassium sulfide, and polysulfides such as sodium polysulfide and potassium polysulfide. , sulfites such as sulfite, sodium sulfite, ammonium sulfite, and thiosulfates such as sodium thiosulfate and ammonium thiosulfate are effective.

Generally, it is preferable to use these sulfur compounds in an amount of 0.1 to 10% based on the brominated diphenyl ether. When the sulfur compound is solid and insoluble or poorly soluble in the organic solvent used in the present invention, it is added after being pulverized. The reaction is preferably carried out under stirring. The reaction temperature in the presence of a reducing sulfur compound is room temperature or the boiling point of the solvent.If the reaction is carried out at room temperature, the reaction time must be longer; If this is the case, the reaction time may be shortened.

The brominated diphenyl ether thus obtained is stable against light, especially ultraviolet light, and when added to plastics as a flame retardant, especially polyolefins such as polystyrene, polypropylene, and polyethylene, it can be used as a brominated diphenyl ether purified by simply recrystallizing with an organic solvent. It has been found that this material exhibits significantly superior weather resistance compared to plastics containing diphenyl ether as a flame retardant. This will be explained in detail using an example below.

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 xylene and heated to 130°C to dissolve.

1 part by weight of sodium hydrogen sulfide was added to this and stirring was continued for 2 hours. The crystals obtained by filtering under heat and cooling were thoroughly washed with methanol and water and then dried to obtain 92 parts by weight of brominated diphenyl ether. Analysis value C: 16.2%
, Br: 82.1%, average composition Cl2HBr,O Example 2 100 parts by weight of crude decapromphenyl ether obtained by brominating diphenyl ether was mixed with 10 parts by weight of acetone.
00 parts by weight, suspended, added sodium sulfite, and stirred at room temperature for 10 hours.

After the crystals were separated, they were thoroughly washed with water and dried to obtain 90 parts by weight of brominated diphenyl ether. Analysis value C: 17.6%,
Br: 80.7%, average composition Cl2Hl7Br8.80
Example 3 100 parts by weight of crude brominated diphenyl ether obtained by brominating diphenyl ether with bromine was added to 2000 parts by weight of xylene, and the mixture was heated to 130°C to dissolve.

5 parts by weight of sodium polysulfide was added to this, and stirring was continued for 3 hours. After filtration under heat, the P solution was cooled and the resulting crystals were separated and dried to obtain 90 parts by weight of brominated diphenyl ether. Analysis value C: 17.0%, Br: 80.5%,
Average composition: C, 2H, .5Br8.50 Example 4 100 parts by weight of crude decapromphenyl ether obtained by brominating diphenyl ether was added to 1000 parts by weight of acetic acid and heated to 60°C.

To this, add 8 parts by weight of potassium sulfide little by little.
Stirring was continued for an hour. After cooling, the crystals were separated and dried to obtain 94 parts by weight of brominated diphenyl ether. Analysis value C
: 16.5%, Br: 81.9%, average composition Cl2HB
r9O Reference Example To 100 parts of styrene resin, 15 parts each of brominated diphenyl ether obtained by recrystallizing with xylene or brominated diphenyl ether obtained by reacting in the presence of a sulfur compound according to the above example was added. A small amount of ultraviolet absorber, heat stabilizer, etc. are added, and the mixture is thoroughly kneaded and molded at a temperature of 240° C. or lower.

The obtained molded product was subjected to a weather resistance test using a weatherometer. The results are shown in the table. It should be noted that no influence of the added flame retardant was observed on the impact strength, heat distortion temperature, and other physical properties of the resin.

Claims (1)

[Claims] 1 A method for producing light that is characterized by reacting brominated diphenyl ether containing decabromodiphenyl ether as a main component in the presence of a sulfur compound having reducing properties in an organic solvent containing hydrogen that can be exchanged with bromine under the reaction conditions. Method for producing stable brominated diphenyl ethers.