DE3120557C2 - Het-acid-bis-pentabromobenzyl ester, process for its preparation and its use as a fire retardant - Google Patents

Abstract

The HET acid bis-pentabromobenzyl esters, which are suitable as fire retardants for thermoplastics, optionally together with antimony trioxide, are obtained by reacting the aqueous solution of an alkali metal salt of HET acid with pentabromobenzyl bromide with the addition of a glycol ether, water being azeotropically distilled off from the reaction mixture .

Description

Cl

r - CO-CH ₂

Lc-O-CH ₂

Cl

2. A process for the preparation of HET acid bis-pentabromobenzyl ester, characterized in that an approximately 30% aqueous solution of an alkali metal salt of HET acid is first prepared, about half of the water is distilled off, a solvent from the group of glycol ethers, preferably ethyl glycol, is added to and distilled off from the resulting reaction mixture, the water azeotropically, is reacted and then the present in the anhydrous solvent alkali salt of HET acid with Pentabrombenzylbromid at a temperature of 50 to 130 ⁰ C.

3. The method according to claim 2, characterized in that reacting the alkali metal salt of HET acid with Pentabrombenzylbromid at 70 to 100 ⁰ C.

4. Use of the product according to Claims 1 to 3, characterized in that it is used as a fire retardant for thermoplastics in amounts of 3 to 30% by weight. based on the amount of plastic, optionally in conjunction with antimony trioxide is used.

The present invention relates to a novel flame retardant compound which is non-exuding Flame retardant components for plastics containing styrene, such as HIPS (high impact polystyrene) or ABS polymers or represents saturated polyester. The compound according to the invention optionally causes with the use of antimony trioxide an excellent fire protection for these plastics.

HET acid anhydride (= 1,4,5,6,7,7-hexachlorobicyclo- [2,2,1] -hept-5-ene-2,3-dicarboxylic anhydride) of the formula

Cl

is a maleic anhydride adduct with hexachlorocyclopentadiene. Derivatives of these adducts are used as fire retardants known for plastics. For example, in Chem. Abstracts 80, (1974) Ref. 97 400t, an ester of HET acid with 2 halogenated alkoxy groups known as a fire retardant for polymeric materials can be used. However, in order to achieve a satisfactory fire protection, these must HET acid derivatives be admixed with the plastic in amounts of 40 to 50% by weight. Through this substantial Quantities of fire protection components affect the physical and mechanical properties of the plastics Changed very unfavorably, and in addition, in the event of a fire due to the high chlorine content, this exists HET acid derivatives pose a risk of considerable hydrogen chloride development, which would make fire fighting difficult.

Furthermore, from »Ulimann's Encyclopedia of techn. Chemie ", 4th ed., Volume 8 (1974) pages 693 and 694 die Use of brominated aromatics, usually together with synergists, such as antimony trioxide, known as fire protection agents that can be incorporated into polymeric materials.

The object of the present invention is to provide a HET acid compound available that little Contains chlorine, works well as a fire retardant in thermoplastics and is a satisfactory one Shows fire behavior. It should be a compound, the addition of which enhances the properties of the respective

gen plastics are not adversely affected and no surface coating is formed on the plastics due to migration

This object is achieved in the manner claimed

The present invention relates to the HET acid bis-pentabromobenzyl ester and the process for its preparation, which is characterized in that an approximately 30% strength aqueous solution of an alkali salt of the HET acid is first prepared and after about half of the water is distilled off is, a solution center! from the group of glycol ethers, preferably ethyl glycol, is added and the water is azeotropically distilled off from the resulting reaction mixture, whereupon the alkali metal salt of the HET acid with pentabromobenzyl bromide present in the anhydrous solvent at a temperature of 50 to 130 ⁰ C, preferably 70 to 100 ⁰ C, is implemented.

The present invention thus obtained HET acid-bis-pentabrombenzylester is a nearly colorless fine product with a melting range of about 26O ⁰ C and provides excellent fire retardants for thermoplastic polymers such as styrene-containing polymers or saturated polyester, is that even under severe conditions of the respective plastics in which it is incorporated does not exude or form any surface covering and thus does not change the mechanical properties of the plastic

To prepare the HET-Säureesters invention HET-acid anhydride is first suspended in water and treated with an equimolar amount of sodium hydroxide at a temperature of about 8O ⁰ C, with stirring, neutralized From the thus obtained Na salt solution the HET-acid is then about half of the used Amount of water distilled off An appropriate amount of ethyl glycol is added to the remaining sodium salt solution of the HET acid and, while stirring, the remaining water is azeotropically distilled off from the reaction mixture until the distillation temperature remains constant at the boiling point of the ethyl glycol of 128 ° C Additional ethyl glycol can be added to the distillation process 2 to 3 times. After in this way all the water has been removed from the reaction solution, the solution is cooled to a temperature of about 70 ⁰ C and by adding a äqimolaren amount Pentabrombenzylbromid the course of several hours at a temperature of 50 to 130 ⁰ C, preferably at 70 to 10O ⁰ C, reacted. The precipitated product is filtered off after cooling the reaction mixture to room temperature. It is first washed with methanol and then with water and ^{dried at a temperature of 80 0} C. The HET acid-bis-pentabromobenzyl ester is in a Yield of about 90% of the

§ Receive theory and the analytical values determined correspond almost to the theoretical values. Of the

ψ The melting point of this compound is above 260 ^° C.

|| The following example explains the production of the product according to the invention in more detail and is shown in

> 'The table below shows examples of its use as a fire retardant for ABS polymers or

Polybutylene terephthalate indicated. In addition, the test results of the according to

p the example prepared HET acid bis-pentabromobenzyl ester under the same conditions the decab

fj Romdiphenylether compared as a comparison substance

5: ;; example

Il 75 parts by weight (GT) of HET acid anhydride in 300 GT of water are placed in a reaction vessel and

i | neutralized with 16GT sodium hydroxide with stirring at a temperature of 20 to 8O ⁰ C. Von der so

f '_; obtained Na salt solution of the HET acid are then distilled off 150 parts by weight of water and added to the remaining

'f benden aqueous solution are added without first cooling 600 pbw of ethyl glycol and the remainder

ψ Water is distilled off azeotropically until a constant boiling temperature of 128 ° C is reached.

I borrowed that two or three times more 100 pbw of ethylglycol be added to the distillation mixture. After everything

Water has been removed from the reaction mixture. There is a solvent content of 600 pbw of ethylglycol in the reaction mixture. Then after cooling to 70 ⁰ C the anhydrous Na salt solution of the <: HET acid, which partly also contains undissolved sodium salt, 226 pbw of pentabromobenzyl bromide added initially

a reaction temperature of 70 ⁰ C is maintained for 2 hours, then a further 2 hours and 8O ⁰ C '). ultimately the reaction was completed ^{at 100 °} C. in a further 2 hours. The failed product is after the so

Sucked off cooling to room temperature and washed 2 times with 100 pbw of methanol each time. Then it will Washed 3 times with 200 pbw of water each time before it is suctioned off and dried at 80 ° C.

The HET acid bis-pentabromobenzyl ester obtained is an almost colorless, finely divided product. The yield of 243 GT corresponds to 89.4% of theory.

The bromine content is 58.7% and the chlorine content is 15.5%. The melting point of the HET acid ester is above 260 ° C

Tabel

(1) = blank sample

(2) = HET acid bis-pentabromobenzyl ester

5 (3) = decabromodiphenyl ether (BROMKAL E 82) (comparison)

ABS polymer

(1) (2) (3)

Polybutylene terephthalate (1) (2) (3)

ίο Composition in Vo

plastic 100 74 77 100 85 86 Product (invent, acc.) - 21 - - 11th - BromkalE82 (VergL) - - 18th - - 10 Antimony trioxide - 5 5 - 4th 4th Fire tests ASTM-D 635-74, afterburn time / sec 178 5 285 5 ASTM-D 635-74, max.burning length / mm 100 17th 100 15th ASTM-D 2863-74, oxygen% 18.5 27 UL94 class Plate thickness 1.6 mm HB V-O V-O HB V-O V-O Piattenst 3.2 mm HB V-O V-O HB V-O V-O Exudation tests *) 42 days at 80 ⁰ C, weight loss% 1.1 2.7 5 days at 140 ° C, weight loss% 035 2.5 14 days at 50 ° C. 0.4 100% rel. Moist weight loss Surface covering no stronger no stronger Topping Topping Topping Topping

*) The weight loss is based on the amount of fire retardant used.

Claims (1)

Patent claims: 1. HET acid bis-pentabromobenzyl ester of the form!
CI Cl-1 Cl-I Cl