JPH05287014A - Production of brominated polystyrene - Google Patents

Abstract

PURPOSE:To efficiently obtain a high-purity brominated polystyrene excellent in color tone from polystyrene and bromine by using a Lewis acid catalyst in an organic solvent to conduct the bromination. CONSTITUTION:A Lewis acid catalyst is dissolved in an organic solvent with heating in an amount of 2-10% by mole based on the benzene rings of polystyrene to be brominated. The bromination is conducted in this solution at 10-40 deg.C.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing brominated polystyrene useful as a heat resistant flame retardant.

[0002]

It is known to obtain brominated polystyrene from polystyrene and bromine using a Lewis acid catalyst in an organic solvent. It is also known that the Lewis acid catalyst with the highest yield is aluminum chloride, aluminum bromide or the like. However, the Lewis acid is used in a large amount, usually 2 to 15 mol%, and the reaction is carried out in a heterogeneous system in which these catalysts are dispersed in an organic solvent.

The most effective heat-resistant flame retardant is
The bromine is obtained by substituting 2 to 3 bromine atoms per benzene ring, and by substituting 2 to 3 bromine atoms per benzene ring by such a method. There is a problem that the coloring of the modified polystyrene is large.

In order to improve the coloring of the obtained brominated polystyrene, Japanese Patent Publication No. 61-34723 discloses a method of adding a basic substance to a Lewis acid.
Japanese Patent Laid-Open Publication No. 2-21 / 1990, in which a double salt of an alkali metal halide and an iron halide is used as a catalyst.
Japanese Patent No. 5807 proposes a method of using phosphorus pentoxide to bring the reaction system into an anhydrous state, and all of these methods are industrially excellent methods satisfying all of color tone, purity, and yield. It's hard to say.

[0005]

In a reaction for obtaining brominated polystyrene from polystyrene and bromine by using a Lewis acid catalyst in an organic solvent, a method for obtaining highly pure brominated polystyrene with excellent color tone in a high yield was found. It is to send out.

[0006]

Means for Solving the Problems As a result of extensive studies to solve the above-mentioned problems, the causes of poor color tone and purity in the conventional method are aluminum chloride and bromide suspended and dispersed in an organic solvent. This is because the product agglomerates and precipitates in the form of a gum on a Lewis acid catalyst such as aluminum, which makes purification difficult, and a Lewis acid catalyst such as aluminum chloride or aluminum bromide must be completely used as a reaction solvent in advance. The present invention was found to solve this problem by dissolving it in a bromine and performing a bromination reaction using the solution as a reaction solvent.

That is, the present invention uses a Lewis acid catalyst in an organic solvent in the reaction of obtaining a brominated polystyrene from polystyrene and bromine by using 2 to 10 mol% of the Lewis acid catalyst per 1 mol of the benzene ring in the polystyrene. The method for producing brominated polystyrene is characterized in that a Lewis acid catalyst is dissolved in advance in an organic solvent by heating, and then the bromination reaction of polystyrene is carried out in this solution at 10 to 40 ° C. The polystyrene used in the present invention, which will be described in order below, has a degree of polymerization of about 30,000 to 500,000 in terms of weight average molecular weight. More preferably 50,000 to 250,000
0 is preferable. When the weight average molecular weight is 30,000 or less, the product tends to be pale yellow. On the other hand, the higher the weight average molecular weight, the smaller the coloration, but it is practically usable up to about 500,000.

Examples of the organic solvent used in the present invention include aliphatic halogenated hydrocarbons such as dichloroethane, trichloroethane, tetrachloroethane, dichlorodibromoethane, dibromoethane, tetrabromoethane and carbon tetrachloride. These may be not only anhydrous solvents, but also recovered solvents containing water having a solubility not higher than that which is often used industrially. Of these solvents, dichloroethane is preferred.

Examples of the Lewis acid catalyst used in the present invention include aluminum chloride, aluminum bromide, iron chloride, iron bromide, etc. These may be used alone or in a mixture. The amount of the catalyst used is 2 to 10 mol% per mol of the benzene ring of polystyrene. More preferably, it is 3 to 6 mol%. When it is less than 2 mol%, the reaction time becomes long, and when it exceeds 10 mol%, the dissolution time becomes long and the coloring of the product becomes large, which is not preferable.

The bromine used as the brominating agent in the present invention is based on 1 mol of the benzene ring in the raw material polystyrene.
It is preferable to use 2.1 to 3.3 mol. When it is less than 2.1 mol, the bromine content of the brominated polystyrene becomes insufficient. On the other hand, if the amount is more than 3.3 mols, the amount of residual bromine increases at the end of the reaction, which is not economical.

In the method of the present invention, first, the Lewis acid catalyst and polystyrene are completely dissolved in the aliphatic halogenated hydrocarbon solvent. It is necessary to heat-dissolve the Lewis acid catalyst in order to completely dissolve it. The heating dissolution temperature is usually 40 to 70 ° C. Polystyrene may be melted at room temperature or by heating. The bromination reaction is carried out by dropping bromine while maintaining the temperature at 10 to 40 ° C, more preferably 20 to 30 ° C.
When the temperature is 10 ° C or lower, the reaction rate is slow, and when the temperature is 40 ° C or higher, the product is colored, which is not preferable. 1-2 more after dropping
The reaction is completed by continuing stirring for 10 hours while maintaining the temperature at 10 to 40 ° C. After the reaction, water is added to the reaction mixture to deactivate the catalyst, and HBr or HCl contained in the aqueous phase is washed away with water. If bromine remains, it is necessary to wash it with an alkaline aqueous solution and water to which a reducing agent such as sodium thiosulfate or sodium sulfite is added. Any method can be used for isolating the brominated polystyrene contained in the organic solvent phase. For example, lower alcohols such as methanol or carbon atoms having 5 to 8 carbon atoms can be used.
The reaction mixture solution may be poured into the saturated aliphatic hydrocarbon of (1) for precipitation, or the solvent may be distilled off under vacuum such as spray drying.

The brominated polystyrene obtained in the present invention is
It has 2 to 3 bromine atoms per benzene ring. For example, polycarbonate, polyester,
It is extremely useful as a flame retardant for plastics such as polypropylene, styrene resin, and polyamide.
When uncolored brominated polystyrene obtained by this method is used, the flame-retarded product has a good color tone, and when conventional colored brominated polystyrene is used, the color tone of the product is greatly impaired and it is not used. It is useful for various purposes.

[0013]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited thereto. The mol% and mol times in the examples and comparative examples are the values for 1 mol of benzene ring in polystyrene.

[0014]

Example 1 A 200 ml four-necked flask equipped with a calcium chloride tube, a reflux condenser, a dropping funnel, and a thermometer was charged with 130 g of dichloroethane, and the liquid temperature was kept at 60 ° C. to give 1 g of anhydrous aluminum chloride (6 mol). %) Was added and the mixture was stirred for 1 hour to completely dissolve aluminum chloride and then cooled to room temperature to obtain a brown transparent solution. 13 g of polystyrene [Elaststyrene 200, manufactured by Dainippon Ink and Chemicals, Inc. 200 weight average molecular weight 55,000] was added to the solution while paying attention to the inclusion of water, and the mixture was stirred and dissolved. 63g at reaction temperature 25 ~ 30 ℃
(3.15 mol times) bromine was added dropwise over 0.5 hours,
After the dropwise addition was completed, the reaction was continued at the same temperature for 1.5 hours to complete the reaction, and then water was added dropwise while paying attention to heat generation to deactivate the catalyst. The aqueous layer was removed, and then the reaction solution was washed successively with a 10% aqueous sodium hydroxide solution and water to obtain a semitransparent orange solution. The reaction solution was poured into 320 g of methanol, and the precipitated crystals were collected by filtration, washed and dried to obtain 41 g of white brominated polystyrene (bromine content 68%).

[0015]

Example 2 A 500 ml four-necked flask equipped with a calcium chloride tube, a reflux condenser, a dropping funnel and a thermometer was charged with 260 g of dichloroethane, and the liquid temperature was kept at 60 ° C. to obtain 1.6 g of anhydrous aluminum chloride ( 4.8 mol%) and stirred for 1 hour to completely dissolve aluminum chloride,
After cooling to room temperature, a light brown transparent solution was obtained. 26 g of polystyrene [Mitsui Toatsu Chemicals Co., Ltd. 500-52 weight average molecular weight 100,000] while paying attention to mixing of water in the solution.
Was added, and the mixture was stirred and dissolved. The reaction solution temperature is 25 to 2 in this solution.
At 8 ° C, 130 g (3.25 mol times) of bromine was added dropwise over 1 hour, and after the addition was completed, the reaction was continued at the same temperature for 2 hours to complete the reaction, and water was added dropwise while paying attention to the heat generation. Deactivated. The aqueous layer was removed, and then the reaction solution was washed successively with a 10% aqueous sodium hydroxide solution and water to obtain a semitransparent orange solution. The reaction solution was poured into 640 g of methanol, and the precipitated crystals were collected by filtration, washed and dried to obtain 84 g of white brominated polystyrene (bromine content 69%).

[0016]

Example 3 A 200 ml four-necked flask equipped with a calcium chloride tube, a reflux condenser, a dropping funnel and a thermometer was charged with 160 g of tetrachloroethane, and the liquid temperature was maintained at 75 ° C. to obtain 2 g of anhydrous aluminum chloride (6 (Mol%) was added and stirred for 1 hour to completely dissolve it, and then cooled to room temperature to obtain a black solution. 13 g of polystyrene [SB-130 weight average molecular weight 62,000 manufactured by Sanyo Kasei Co., Ltd.] was added to the solution while paying attention to the inclusion of water, and the mixture was stirred and dissolved. Reaction liquid temperature 27
0.25g of 63g (3.15 mole times) bromine at ~ 31 ° C
After dropwise addition over a period of time, the reaction was continued at the same temperature for 1.5 hours after completion of the addition to complete the reaction, and then water was added dropwise while paying attention to heat generation to deactivate the catalyst. The aqueous layer was removed, and then the reaction solution was washed successively with a 10% aqueous sodium hydroxide solution and water to obtain a semitransparent orange solution. The reaction solution was poured into 320 g of methanol, and the precipitated crystals were collected by filtration, washed and dried to obtain 38 g of slightly yellow brominated polystyrene (bromine content 67%).

[0017]

Example 4 2.6 kg of dichloroethane was charged into a 5000 ml four-necked flask equipped with a calcium chloride tube, a reflux condenser, a dropping funnel and a thermometer, and the liquid temperature was kept at 65 ° C. to give 39 g of anhydrous aluminum bromide. (5.8 mol%) was added and the mixture was stirred for 1 hour to completely dissolve it, and then cooled to room temperature to obtain a black solution. 260 g of polystyrene [570-57 weight average molecular weight 180,000 manufactured by Mitsui Toatsu Chemicals, Inc.] was added to the solution while paying attention to mixing of water, and the mixture was stirred and dissolved. 1.3Kg (3.25 mole times) of bromine was added dropwise over 4 hours at the reaction liquid temperature of 25 to 28 ° C, and after the addition was completed, the reaction was continued for 2 hours at the same temperature to complete the reaction, and be careful of the heat generation. Drop water,
The catalyst was deactivated. The aqueous layer was removed, and then the reaction solution was washed successively with 10% aqueous sodium hydroxide solution and water. The reaction solution was poured into 6.4 kg of methanol, and the precipitated crystals were collected by filtration, washed and dried to obtain 840 g of white brominated polystyrene (bromine content 69%).

[0018]

Example 5 260 g of dichloroethane was charged into a 500 ml four-necked flask equipped with a calcium chloride tube, a reflux condenser, a dropping funnel and a thermometer, and the liquid temperature was kept at 65 ° C. to give anhydrous aluminum bromide 3.9 g. (5.8 mol%) was added and the mixture was stirred for 1 hour to completely dissolve it, and then cooled to room temperature to obtain a black solution. 26 g of polystyrene [Erastyrene 200, weight average molecular weight: 55,000, manufactured by Dainippon Ink and Chemicals, Inc.] was added to the solution while paying attention to mixing of water, and the mixture was stirred and dissolved. At a reaction liquid temperature of 25 to 28 ° C., 84 g (2.1 mol times) of bromine was added dropwise over 0.5 hour, and after completion of the addition, 2 at the same temperature.
After continuing the reaction for a while to complete the reaction, water was added dropwise while paying attention to heat generation to deactivate the catalyst. Remove the water layer, then 1
The reaction solution was washed successively with a 0% aqueous sodium hydroxide solution and water. The reaction solution was poured into 640 g of methanol, and the precipitated crystals were collected by filtration, washed and dried to obtain 62 g of white brominated polystyrene (bromine content 61%).

[0019]

Example 6 To 100 parts by weight of reinforced polyethylene terephthalate (C-3030 manufactured by Teijin Ltd.) was added 10 parts of the brominated polystyrene obtained in Example 4 and antimony trioxide (ATOX-S; Nippon concentrate). 5 parts (manufactured by Co., Ltd.) were dry blended and extruded, and the obtained flame-retardant resin composition was molded into a test piece. Table 1 shows the b-value measurement results of test pieces which were similarly dry-blended, extruded and molded using this and commercially available brominated polystyrene.

[0020]

[Table 1]

[0021]

Comparative Example 1 In a 200 ml four-necked flask equipped with a calcium chloride tube, a reflux condenser, a dropping funnel and a thermometer, 130 g of dichloroethane and polystyrene [Dainippon Ink and Chemicals, Inc.
Elaststyrene 200, weight average molecular weight 55,000] 13
g was added, and the mixture was stirred and dissolved. Furthermore, the reaction liquid temperature is 25 to 30.
At 0 ° C 1 g (6 mol%) of anhydrous aluminum chloride was added.
63 g (3.15 mol times) of bromine was added dropwise to this over 0.5 hours, and after the addition was completed, the reaction was continued at the same temperature for 1.5 hours to complete the reaction, and water was added dropwise while paying attention to heat generation. , The catalyst was deactivated. The aqueous layer was removed, and then the reaction solution was washed successively with 10% aqueous sodium hydroxide solution and water. As for this product, formation of a dark yellow gum was observed in the reaction solution. The whole reaction solution was poured into 320 g of methanol, and the precipitated crystals were collected by filtration, washed and dried to obtain 35 g of dark yellow brominated polystyrene (bromine content 68%).

[0022]

Comparative Example 2 In a 200 ml four-necked flask equipped with a calcium chloride tube, a reflux condenser, a dropping funnel and a thermometer, 130 g of dichloroethane and polystyrene [Mitsui Toatsu Chemicals, Inc.
Product 500-52, weight average molecular weight 100,000] 13 g was added and dissolved by stirring. Further, 1 g (6 mol%) of anhydrous aluminum chloride was added at a reaction liquid temperature of 25 to 30 ° C. to give 63 g (3.
(15 mol times) bromine was added dropwise over 0.5 hour, and after the completion of the reaction, the reaction was continued at the same temperature for 1.5 hours to complete the reaction, and then water was added dropwise while paying attention to heat generation to deactivate the catalyst. It was The aqueous layer was removed, and then the reaction solution was washed successively with 10% aqueous sodium hydroxide solution and water. As for this product, formation of a brown gum was observed in the reaction solution. The whole reaction solution was poured into 320 g of methanol, and the precipitated crystals were collected by filtration, washed and dried to give dark yellow brominated polystyrene (bromine content 67%) 3
7 g was obtained.

[0023]

Comparative Example 3 In a 200 ml four-necked flask equipped with a calcium chloride tube, a reflux condenser, a dropping funnel and a thermometer, 130 g of dichloroethane, polystyrene [Mitsui Toatsu Chemicals, Inc.].
570-57 weight average molecular weight 180,000] (13 g) was added and dissolved with stirring. Further, 1 g (6 mol%) of anhydrous aluminum chloride was added at a reaction liquid temperature of 25 to 30 ° C. to give 63 g (3.
(15 mol times) bromine was added dropwise over 0.5 hour, and after the completion of the reaction, the reaction was continued at the same temperature for 1.5 hours to complete the reaction, and then water was added dropwise while paying attention to heat generation to deactivate the catalyst. It was The aqueous layer was removed, and then the reaction solution was washed successively with 10% aqueous sodium hydroxide solution and water. As for this product, formation of a dark yellow gum was observed in the reaction solution. 320 g of the whole reaction solution
Of methanol, and the precipitated crystals are collected by filtration, washed and dried to give a dark yellow brominated polystyrene (bromine content 69%).
40 g are obtained.

[0024]

Comparative Example 4 White brominated polystyrene (bromine content 46%) was reacted and purified in the same manner as in Example 1 except that 0.25 g (1.5 mol%) of anhydrous aluminum chloride was used. 21 g are obtained.

[0025]

Comparative Example 5 37 g of dark brown brominated polystyrene (bromine content 68%) which had been reacted and purified in the same manner as in Example 1 except that 2.5 g (15 mol%) of anhydrous aluminum chloride was used in Example 1. Got

[0026]

Comparative Example 6 18 g of white brominated polystyrene (bromine content 31%) was obtained by reacting and purifying in the same manner as in Example 1 except that the reaction temperature was 0 to 5 ° C.

[0027]

Comparative Example 7 The reaction and purification were carried out in the same manner as in Example 1 except that the reaction temperature was changed to 45 ° C. to obtain 38 g of dark brown brominated polystyrene (bromine content 69%).

[0028]

According to the method of the present invention, a brominated polystyrene having a high bromine content and an improved white to slightly yellow color tone can be easily obtained without using any special raw material and equipment. This is a useful flame retardant.

Claims (1)

[Claims] 1. In a reaction for obtaining brominated polystyrene from polystyrene and bromine by using a Lewis acid catalyst in an organic solvent, the Lewis acid catalyst is used in an amount of 2 to 10 mol% based on 1 mol of a benzene ring in the polystyrene. A method for producing brominated polystyrene, which comprises dissolving the catalyst in advance in an organic solvent by heating, and then brominating the polystyrene at 10 to 40 ° C. in this solution.