JP2740455B2 - Method for producing brominated polystyrene - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing brominated polystyrene useful as a flame retardant for synthetic resins.

[0002]

2. Description of the Related Art Brominated polystyrene is used as a flame retardant for various synthetic resins represented by engineering plastics such as saturated polyester and polyamide.
Resins containing these flame retardants are used in electrical and
It is used in various fields such as the electronic field.

Various methods for producing brominated polystyrene have been proposed. For example, Japanese Patent Publication No. 1-57684 discloses polystyrene having a weight-average molecular weight of 20,000 or more in an organic solvent under a condition of anhydrous metal salt Lewis acid bromine. For producing brominated polystyrene by reacting with bromine chloride at a temperature of up to about 50 ° C. in the presence of a bromination catalyst;
Japanese Patent No. 5807 discloses that an aliphatic halogenated hydrocarbon is used in the presence of a Lewis acid catalyst in the presence of a Lewis acid catalyst in the presence of a dehydrating agent.
There has been proposed a method for producing brominated polystyrene in which polystyrene is brominated at ℃ 40 ° C. However, since all of these methods use a Lewis acid as a bromination catalyst, it is necessary to carry out the bromination reaction under anhydrous conditions or at least a water content of 0.02% or less in the reaction solvent. If more moisture is present, the Lewis acid catalyst decomposes and bromination does not proceed as expected, so that brominated polystyrene having a high bromine content and excellent heat resistance that can be used as a flame retardant cannot be obtained. In addition, since the Lewis acid catalyst is decomposed even by moisture in the air, sufficient control is required for storage. From such a point, the conventional production method was not satisfactory as an industrial production method.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve such problems and to provide brominated polystyrene which is excellent as a flame retardant for synthetic resins.

[0005]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, have found that the use of antimony oxide as a catalyst during the bromination of polystyrene allows the use of hydrous conditions. The reaction proceeded even below, and the resulting brominated polystyrene was found to be excellent in color tone and heat resistance, and was found to be useful as a flame retardant for synthetic resins, and reached the present invention.

That is, the present invention is a process for producing a brominated polystyrene, which comprises reacting polystyrene dissolved or dispersed in a halogenated hydrocarbon solvent with a brominating agent in the presence of an antimony oxide catalyst. .

Hereinafter, the present invention will be described in detail. As polystyrene to be subjected to the bromination of the present invention, polystyrene,
Styrene-maleic anhydride copolymer, polyethylene-styrene graft copolymer, styrene-butadiene copolymer, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, styrene-divinylbenzene cross-linked copolymer, etc. Those containing 50% by weight or more of a styrene component are used. Also,
These foams and their recovered products can also be used.

The halogenated hydrocarbon solvents used in the present invention include chlorinated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride, ethylene dichloride, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethylene and monochlorobenzene; Methylene bromide,
Brominated hydrocarbons such as ethylene dibromide.

As the brominating agent used in the present invention, bromine or bromine chloride can be used. As antimony oxide which is a bromination catalyst, diantimony trioxide, diantimony tetroxide, diantimony pentoxide and the like are used. The amount of the catalyst to be added is preferably 1 to 30 parts by weight based on 100 parts by weight of polystyrene.

The water content in the bromination reaction is 0.02 to the reaction solvent as in the case of using a Lewis acid catalyst.
% Need not be substantially anhydrous. The preferred water content is at most 5%, more preferably at most 2%, based on the reaction solvent.

[0011] The bromination reaction of the present invention is carried out at a temperature of -20 ° C to 100 ° C.
It is preferable to carry out in. After completion of the reaction and aging, the excess brominating agent is reduced or neutralized, and further washed with water and neutralized, and then the reaction solvent is concentrated and distilled off from the obtained brominated polystyrene solution, or the brominated polystyrene solution is removed. By adding the compound in a poor solvent such as methanol, a solid or powder of brominated polystyrene can be obtained.

The brominated polystyrene obtained by the method of the present invention can be blended as a flame retardant with various synthetic resins such as thermoplastic resins, thermosetting resins, and thermoplastic elastomers. Examples of these resins include styrene resins such as polystyrene and acrylonitrile-butadiene-styrene copolymer; polyolefins such as polyethylene and polypropylene; saturated polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyamides such as nylon 66 and nylon 46; Modified polyphenylene ether and the like can be mentioned.

[0013]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 In a 1-liter glass reactor (provided with a stirrer, condenser, thermometer and dropping funnel), 750 g of ethylene dichloride (water content 0.002%) and polystyrene (Mitsubishi Kasei Polytex, trade name: Diamond) Rex) 75 g
After stirring and dissolving, 11 g of diantimony trioxide was added,
While maintaining the reaction temperature at 10 to 25 ° C., a bromine chloride solution prepared in advance (70% by weight ethylene dichloride solution)
720 g was dropped from the dropping funnel over 2 hours. After completion of the dropwise addition, the mixture was aged for 1 hour while maintaining the internal temperature at 20 to 30 ° C. After aging, the reaction product was washed with water, and the organic layer was dropped into 3 L of methanol for crystallization. After the crystals were filtered and dried, 216 g of brominated polystyrene powder was obtained. The bromine content, TG (thermogravimetric analysis), appearance hue, and heat-generated HBr amount of the brominated polystyrene were measured by the methods described below. Table 1 shows the analysis results.

-Bromine content: measured by a method according to JIS K 7299 (flask combustion method). TG (thermogravimetric analysis): Measurement was performed from room temperature to 700 ° C. at a rate of 10 ° C./min in an air atmosphere using a differential calorimeter (manufactured by Rigaku).・ Appearance hue: Colorimeter (CR-1 made by Minolta Camera)
00 type), and the values of L, a, and b display systems were determined. Amount of HBr generated by heating: A heating tube was set in an electric furnace, and further connected to a gas absorbing bottle (100 ml of distilled water) equipped with a blowing tube. 3 g of a sample is placed in a heating tube, and nitrogen gas (about 5
(0 ml / min) in an electric furnace at 200 ° C. for 1 hour. The bromine content in the gas-absorbed water was quantitatively analyzed by the Volhard method.

Example 2 Bromination and post-treatment were carried out in the same manner as in Example 1 except that diantimony pentoxide was used instead of diantimony trioxide to obtain 215 g of brominated polystyrene powder.
I got Table 1 shows the analysis results of the obtained powder.

Example 3 A brominated polystyrene powder was prepared in the same manner as in Example 1 except that foamed polystyrene for cushioning material (Aspac Kasara Asahi Kasei) was used instead of polystyrene. 224 g were obtained. Table 1 shows the analysis results of the obtained powder.

Example 4 Bromination and post-treatment were carried out in the same manner as in Example 1 except that 750 g of ethylene dichloride and 7.5 g of water were used instead of 750 g of ethylene dichloride. 206 g of powder was obtained. Table 1 shows the analysis results of the obtained powder.

Comparative Example 1 In Example 1, without using diantimony trioxide,
Bromination and post-treatment were carried out in the same manner as in Example 1 to obtain 136 g of brominated polystyrene powder. Table 1 shows the analysis results of the obtained powder.

Comparative Example 2 In the same manner as in Example 1, except that antimony trichloride was used instead of diantimony trioxide, and 750 g of ethylene dichloride and 7.5 g of water were used instead of 750 g of ethylene dichloride. Bromination and post-treatment were carried out by a suitable method to obtain 148 g of brominated polystyrene powder. Table 1 shows the analysis results of the obtained powder.

Comparative Example 3 Example 1 was repeated except that anhydrous aluminum chloride was used in place of diantimony trioxide and 750 g of ethylene dichloride and 7.5 g of water were used in place of ethylene dichloride. Bromination and post-treatment were carried out by the method to obtain 146 g of brominated polystyrene powder. Table 1 shows the analysis results of the obtained powder.

[0022]

[Table 1]

The brominated polystyrene obtained in Examples 1 to 4 was blended with a reinforced PET resin and a nylon 66 resin,
The molded product obtained after kneading / pelletizing, pellet drying, and injection molding had excellent appearance, flame retardancy, and mechanical strength.

[0024]

The method for producing brominated polystyrene according to the present invention is easy to industrialize and excellent in economic efficiency. Further, the brominated polystyrene obtained by the method of the present invention is useful as a flame retardant for a synthetic resin because of its excellent heat resistance and appearance hue. The molded product obtained by blending the flame retardant is excellent in appearance, flame retardancy and mechanical strength, and has high commercial value.

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Claims (1)

(57) [Claims] 1. A process for producing brominated polystyrene, comprising reacting polystyrene dissolved or dispersed in a halogenated hydrocarbon solvent with bromine chloride in the presence of an antimony oxide catalyst.