GB1582875A

GB1582875A - Fire retardant polymeric compositions containing brominated phenyl arylsulphonates

Info

Publication number: GB1582875A
Application number: GB32824/77A
Authority: GB
Original assignee: Akzo NV
Current assignee: Akzo NV
Priority date: 1976-08-17
Filing date: 1977-08-04
Publication date: 1981-01-14
Also published as: CA1116628A; NL7609098A; FR2362185A1; FR2362185B1; DE2736696A1

Description

(54) FIRE RETARDANT POLYMERIC COMPOSITIONS CONTAINING BROMINATED PHENOL ARYLSULPHONATES (71) We, AKZO N.Y., a Company organised and existing under the laws of the Kingdom of the Netherlands, of Ijssellaan 82, Arnhem, the Netherlands, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to fire retardant polymer compositions containing certain brominated phenyl arylsulphonates. In particular, the invention relates to fire retardant polymer compositions having a basis of polystyrene and/or a polyolefin, more particularly polypropylene.

Accordingly, in one aspect the present invention provides a fire retardant polymer which has a basis of polystyrene which contains at least one compound of the general formula:

whereinqis I or2andwhenq= 1,thenr=0, 1 or2,n=3,4OrS,andr+nS5,Ais an alkyl group containing not more than 9 carbon atoms, and wherein when q = 2, then n = 2, 3 or 4, and when r = 0 the two structural units in the para position are directly interlinked or when r= 1 the two structural units in the para position are linked by an oxygen atom, an SO group or an isopropylidene group represented by A, and wherein further X is an NO2, Cl, Br,

CN, OR2 or COOR2 group and R1 and R2 may be the same or different and each represent a substituted or unsubstituted alkyl group having from 1 to 12 carbon atoms, an acetyl or an allyl group, p and m each being 0 or an integer of from 1 to 3, and m + p S 5.

In another aspect, the present invention provides a fire retardant polymer composition which has a basis of a polyolefin and which contains at least one compound having the general formula:

wherein q is 1 or 2 and when q = 1, then r = 0, 1 or 2, n = 3, 4 or 5, and r + n 9 5, A is an alkyl group containing not more than 9 carbon atoms, and wherein when q = 2, then n = 2, 3 or 4, and when r = 0 the two structural units in the para position are directly interlinked or when r= 1 the two structural units in the para position are linked by an oxygen atom, an SO group or an isopropylidene group represented by A, and wherein further X is an NO2, Cl, Br,

CN, OR2 or COOR2 group and R, and R2 may be the same or different and each represent a substituted or unsubstituted alkyl group having from I to 12 carbon atoms, an acetyl or an allyl group, p and m each being O or an integer of from 1 to 3, and m + p < 5, provided that when q = 1 and r = O, or when q = 2 at least one group R, is a substituted alkyl group having from 9 to 12 carbon atoms or at least one group X is an NO2

CN,OR2 or COOR2 groups.

Certain compounds structurally related to those above and intended for the same use have been described in Japanese Patent Specification No. 33178/1974.

The compounds described in this specification correspond to the general formula:

where R1, R2 or R2 may represent a brominated phenyl group. In these compounds only R, can contain three or more bromine atoms. Substitution of three or more bromine atoms in the groups R2 or R3 is not possible, unless R2 or R3 is an aliphatic group. These known compounds also often possess the disadvantage of having a low fastness to light. Moreover, the preparation of the known compounds is generally more costly than the preparation of the compounds used in the present invention.

Other structurally related compounds are described in United States Patent Specification No. 3,850,972. Mention is made, amongst others, of the compound 2,4,6-tribromo-phenyl bromomethane sulphonate. A disadvantage of this compound is its low hydrolytic stability.

Furthermore, the compound 2,4,6-tribromophenyl p-toluenesulphonate and its preparation are known per se from Chemical Abstracts 19, 980 (1925). There is no disclosure therein of the suitability of this compound as a fire retardant in polymer compositions.

Although the compounds used in the present invention may contain some bromine in an aliphatic chain as a result of substitution in the groups R1 and/or R2 by one or more bromine atoms, the presence of bromine bonded to the aromatic system, and more particularly to the group derived from a phenol, is considered to be essential. Belgian Patent Specification No 737,979 disclosed compounds in which the bromine is exclusively bonded to the aromatic system, but the presence of an aliphatic bromine compound was also required in order to obtain a polymer displaying sufficient fire-retardant activity. It is very surprising that the use of fireretardant compounds in which the bromine is exclusive!y bonded to the aromatic system leads to such good results. According to John W. Lyon's "The Chemistry and Uses of Fire Retardants", Wiley-Interscience, New York (1970), nuclearbrominated styrene is far less effective than for instance vinyl bromide. It is therefore concluded in this reference (p. 327) that the use of brominated aliphatic compounds is to be preferred.

The bromine compounds used in the present invention are at least as effective as the known synergistic mixtures in which the bromine is contained in a separate aliphatic compound. Their great advantage, however, is that only one compound need be used. Moreover, the compounds of the invention possess good stability so that under the usual process conditions decomposition hardly occurs.

Suitable substituents in the groups R1 and R2 are all groups that have no unfavourable influence on the fire-retardant activity or on some other property of the composition to be made fire-retardant and that also have a favourable effect on the compatibility between the composition to be made fire-retardant and the fireretardant compound. Examples of suitable substituents are fluorine, chlorine, bromine, hydroxyl, alkyl, aryl, nitro, alkoxy, carboxyl, carboxyl ester and cyano. If the fire-retardant compound tends to exude from the composition to be made fireretardant or if there is a tendency to segregation, it may be advantageous to use such substituents that the fire-retardant compound of the invention is chemically bonded to the composition to be made fire-retardant. This may be effected by providing functional substituent groups such as hydroxyl, amino or carboxyl, which may, by using a radical initiator, be bonded to the ethylenically unsaturated groups contained in the substance to be made fire-retardant.

A few examples of fire-retardant compounds suitable for use in the fire retardant polymer compositions of the invention are listed in the following table.

TABLE 1 1. 2,4,6-Tribromophenyl 2,4,6-triisopropyl benzene sulphonate 2. 2,4,6-Tribromophenyl 2,4,6-trimethyl benzene sulphonate 3. 2,4,6-Tribromophenyl benzene sulphonate 4. 2,4,6-Tribromophenyl p-allyl benzene sulphonate 5. 2,4,6-Tribromophenyl p-2,3-dibromopropyl benzene sulphonate 6. 2,4,6-Tribromophenyl p-2,3-dibromopropoxy benzene sulphonate 7. 2,3,5,6-Tetrabromophenyl p-methyl benzene sulphonate 8. 2,4,6-Tribromophenyl p-(2,2-dichloro- 1, 1-difluoroethoxy) benzene sulphonate 9. 2,4,6-Tribromophenyl p-dodecyl benzene sulphonate 10. Diester of tetrabromobisphenol A with 2,4,6-triisopropyl benzene sulphonic acid 11. 2,3,4,5,6-Pentabromophenyl p-allyloxybenzene sulphonate 12. 2,4,6-Tribromophenyl 2,4-dichlorobenzene sulphonate 13. 2,4,6-Tribromophenyl p-acetoxybenzene sulphonate 14. 2,4,6-Tribromophenyl 2,4-dinitrobenzene sulphonate 15. 2,4,6-Tribromophenyl 2-chloro-4-carboxy ethyl benzene sulphonate 16. Diester of tetrabromobisphenol F with 2,4,6-trimethyl benzene sulphonic acid.

These compounds can be incorporated in the polymeric compositions of the invention at the processing temperatures usual for these polymers without decomposition taking place. In contrast to the results with most other fireretardant compounds, incorporation in polystyrene, for example, does not lead to the polymer turning brown. Furthermore, the transparency of this polymer is not, or hardly, influenced by the incorporation of these compounds. There is therefore generally no need to incorporate into the polymer to be processed substances which render harmless certain decomposition products, such as HBr. If there is still a need for such compounds, then use may advantageously be made of the following compounds.

Organotin compounds such as dibutyltinbis (octylthiopropionate), lead compounds such as lead sulphate and lead oxide, metallic soaps such as cadmium stearate and basic lead stearate, organic phosphites such as triisodecyl phosphite and triphenyl phosphite and epoxy oils such as epoxidized soybean oil. Under some circumstances the fire retardant activity of the compounds of the invention may be enhanced by the incorporation of triphenyl phosphate (TPP) or antimony oxide.

This list is, of course, not limitative and other substances may also advantageously be used besides the present bromine compounds.

The bromine content of the polymeric compositions of the invention is generally in the range of from 0.1% by weight to up to at most 5% by weight. A bromine content of from 0.5 to 2% by weight is preferred. Generally, the amount of fire-retardant bromine compound together with the amount of one or more of the other additives should not be greater than 5% by weight of the polymer. Although larger amounts may also be used, they often have a negative effect on the properties of the polymer. The bromine compounds give particularly good results with polystyrene and polyolefins such as polypropylene, polyethylene and/or polybutadiene. By the term "polymer compositions having a basis of polyolefin" are meant polyolefins and copolymers thereof, which copolymers contain at least 50 percent by weight of the olefin. By the term "polymer compositions having a basis of polystyrene" are meant polystyrene and copolymers thereof, which copolymers contain at least 50 percent by weight of styrene.

Monomers that may be incorporated in the copolymers are a-methyl styrene, acrylonitrile, methacrylonitrile, esters of acrylic or methacrylic acid with alcohols haing from 1 to 8 carbon atoms, esters of fumaric acid with alcohols having from 1 to 8 carbon atoms, vinyl pyridine, N-vinyl compounds, such as N-vinyl carbazole, butadiene or also small amounts, for example 0.001 to 1.0, preferably 0.01 to 0.1, percent by weight of divinyl benzene.

The bromine compounds used in the invention also find application in impact resistant polystyrene composed of styrene and other monomers and finely divided rubbery polymers.

When the fire retardant polymer composition of the invention are in the form of thermoplastics self-extinguishing shaped articles, it is, of course, also possible to incorporate fillers, colourants, pigments, mould release agents, softeners, antistatic agents, aging means, stabilizers or foaming agents therein. The bromine compounds may be incorporated into the thermoplastics moulded articles by mixing with the polymer and, if desired, with other components. This may for example be effected on mixing rollers, in an extruder or on a kneading machine.

They may also be added to the monomers prior to polymerization.

Alternatively, for example in film casting, the bromine compounds may be added to a solution of the plastics material, and the solvent may thereafter be evaporated.

The presence of the compounds prior to polymerization makes it possible to obtain a particularly homogeneous distribution. It has been found that for polystyrene the bromine compounds can be retained even better in the polymer than the known fire-retardant aliphatic bromine compounds. This last-mentioned point is of great importance not only for long-lasting retention of self-extinguishing properties, but also for physiological reasons.

The bromine compounds having the general formula:

whereinqis I or2andwhenq= 1,thenr=0, 1 or2,n=3,4OrS,andr+nA5,Ais an alkyl group containing not more than 9 carbon atoms, and wherein when q = 2, then n = 2, 3 or 4, and when r = 0 the two structural units in the para position are directly interlinked or when r = I the two structural units in the para position are linked by an oxygen atom, an SO2 group or an isopropylidene group represented by A, and wherein further X is an NO2, Cl, Br,

CN, OR2 or COOR2 group and R, and R2 may be the same or different and each represents a substituted or unsubstituted alkyl group having from 1 to 12 carbon atoms, p and m each being 0 or an integer of from I to 3, and m + p < 5, may be prepared by reacting a compound of the formula:

where X, R, m and p are as defined above, in an organic solvent with an alkaline solution of a compound having the general formula:

where A, n, r and q are as defined above, followed by isolating the compound having the above general formula.

In this process various solvents may be used. Suitable solvents are generally those that are inert to the sulphonyl chlorides. They must, moreover, be resistant to an aqueous alkaline solution. Solvents having an aromatic character may advantageously be used, the preferred solvents being benzene or toluene. Very favourable results have been obtained using one of these solvents with sodium hydroxide as the aqueous alkaline solution.

The present invention will be further described with reference to the following Examples, it being understood, however that these Examples are merely given for the purpose of illustration and should not be interpreted as limitative.

The fire-retardant properties in the following Examples were determined using the Oxygen Index (OI) method in accordance with ASTM D 2863-70, unless otherwise stated. The higher the OI value, the more fire-retardant the polymer composition.

In a number of cases the fire-retardant properties were determined using the tests for flammability of Plastic Materials UL-94, 2nd edition (September 1973) of the Underwriters' Laboratories Inc. Melville N.Y., U.S.A. In these tests, referred to in abbreviated form as UL-94 tests, the rating 94-VE-2 is regarded as more fire-retardant then the rating 94 HB.

Example 1.

Preparation of 2,4,6-Tribromophenyl 2,4,6-triisopropyl benzene sulphonate 16.5 grammes of 2,4,6-Tribromophenyl (50 mmoles 2.6 grammes of NaOH (65 mmoles) dissolved in 10 ml of H2O and 75 ml of toluene were charged into a threenecked flask provided with a stirrer, a thermometer, a dropping funnel and a reflux condenser. 15.2 grammes of 2,4,6-triisopropyl benzene sulphonyl chloride (50 mmoles) were added to this mixture over a period of 5 minutes. After stirring for 3 hours at 60"C, 98% of the mixture had been converted. The three-phase system was separated at 60"C. The toluene-containing supernatant layer was concentrated by evaporation. After drying at 500C adn 11 mm Hg., the residue contained 25.2 g of matter containing 94.5% of 2,4,6-tribromophenyl 2,4,6-triisopropyl benzene sulphonate. The product was purified by recrystallization from n-heptane. The resulting white crystalline product had a melting point of 124" to 125"C.

Example II.

Preparation of 2,4,6-tribromophenyl 2,4,6-trimethyl benzene sulphonate 91 grammes of 2,4,6-tribromophenyl (0.275 moles) and 60 grammes of 2,4,6trimethyl benzene sulphonyl chloride (0.275 moles) were mixed with 150 ml of pyridine in a three-necked flask provided with a stirrer, a dropping funnel and a reflux condenser. The mixture thus obtained was stirred for 6 hours at 600C and a .precipitate of pyridine hydrochloride was formed. The reaction mixture was taken up in ether and ice water. After successive washings with cold water, 2NHCl, sodium bicarbonate solution and water, the ether layer was dried with magnesium sulphate.

Evaporation of the ether layer yielded 127 g of product, which upon recrystallization from n-heptane was found to have a melting point of 165 to 165.5"C.

Example III.

Preparation of 2,4,6-tribromophenyl benzene sulphonate In the same way as described in Example I, benzene sulphonyl chloride was added to a mixture of 2,4,6-tribromophenol, sodium hydroxide and toluene. After stirring for 3 hours at 600C the reaction mixture was treated as described in Example I. The melting point of the resulting 2,4,6-tribromophenyl benzene sulphonate was from 83.20 to 84.20 C.

Example IV.

Preparation of the 2,4,6-tribromophenyl p-methyl benzene sulphonate In the same way as described in Example I, p-methyl benzene sulphonyl chloride was added to a mixture of 2,4,6-tribromophenol, sodium hydroxide and toluene. After further treatment and recrystallization a product was obtained having a melting point of from 113 to 1 140C.

Example V.

Fire-retardant polystyrene (Comparative Example) Several batches of polystyrene chips (marketed by Badische Anilin and Sodafabrik under the trade name Polystyrol 145 D Glaskar 012) together with successively 1.4, 4.1 and 6.8% by weight of 2,4,6-tribromophenyl methane sulphonate were dissolved in dichloromethane (approximately one part of solid matter in five parts of solvent). After pouring onto a glass plate and drying in air, a film was obtained which was further dried for 2 hours in vacuo at 1000C. After the film had been cooled, it was ground to a fine powder in a cross beater mill. The powder was pressed into rectangular test bars 150 x 6.5 x 3 mm at a temperture of 1500C and over a period of time of about 12 minutes. The Oxygen Index (owl) of the bars obtained was determined. The results are given in the following table.

TABLE 2

% by weight brominated % by weight bromine Run compound in polymer composition Ol 1 0 0 18.3 2 1.4 0.8 20.2 3 4.1 2.4 22.0 4 6.8 4.0 23.8 Example VI.

Fire-retardant polystyrene Example VI.

The preparation of fire-retardant polystyrene was carried out in the manner described iri Example V, except that the following fire-retardant compounds were used in accordance with the invention, namely: 2,4,6-tribromophenyl benzene sulphonate; and 2,4,6-tribromophenyl p-dodecyl benzene sulphonate.

The results are given in the following table.

TABLE 3

2;4,6-tribromophenyl % by weight 2,4,6-tribromophenyl pdodecyl benzene bromine in benzene sulphonate sulphonate polymer Run %-by weight % by weight composition Ol 1 1.6 0.8 20.9 2 4.7 2.4 24.2 3 7.9 4.0 26.0 4 2.1 0.8 20.3 5 6.4 2.4 23.0 6 10.6 4.0 25.0 The table clearly shows that at the same percentage by weight of bromine in the polymer, the measured OI value is higher for the compounds used in accordance with the invention than for the compound used in Example V. Another advantage of the compounds used in the present invention over a compound such as that of Example V is their far higher resistance to hydrolysis.

Example VII.

Fire-retardant polystyrene (Comparative Example) The preparation of fire-retardant polystyrene was carried out in the manner described in Example V, except that the following compounds were used: A. p-bromophenyl p-toluene sulphonate B. N- (p-bromophenyl) p-toluene sulphonamide (of the above-mentioned Japanese Patent Specification No 33178/1974).

The results are given in the following table.

TABLE 4

lo by weight bromine in % by weight % by weight polymer Run compound A compound B composition Ol 1 2.2 0.5 18.S 2 6.5 1.6 19.4 3 10.8 2.7 19.9 4 2.2 0.5 18.6 5 6.5 1.6 19.4 6 10.8 2.7 20.3 The results given in the above table clearly show that at the same percentage by weight of bromine in the polymer, the measured OI values of the compounds used in this Example are far lower than of the compounds used in accordance with the invention (Table 3).

Example VIII.

Fire-retatdant polystyrene The preparation of fire-retardant polystyrene was carried out in the manner described in Example V, except that 2,4,6-tribromophenyl 2,4-dichlorobenzene sulphonate was used. The results are given in the following table.

TABLE 5

% by weight bromine in % by weight 2,4,6-tribromophenyl polymer Run 2,4-dichlorobenzene sulphonate composition OI 1 1.0 3.4 19.4 2 3.0 1.3 20.9 3 5.0 2.2 23.0 Example IX.

Fire-retardant polystyrene Ninety-six parts by weight of polystyrene powder obtained by grinding polystyrene granules (marketed by Badische Anilin and Sodafabrik under the trade name Polystyrol 145 D Glaskar 012) were intimately mixed with four parts by weight of 2,4,6-tribromophenyl 2,4,6-triisopropyl benzene sulphonate. The resulting mixture was extruded using a laboratory extruder provided with a screw having a diameter of 19 mm, a length of 380 mm and a compression ratio of 2.5: l, of the type commonly used for processing polystyrene. The extrusion temperature was 1800C and the speed of the screw was set to a value such that the mean residence time of the polystyrene mixture in the heated part of the extruder was about 1 minute. The screw-shaped extruded product having a diameter of 2 to 3 mm was chopped into 4 mm long chips. The chips so-obtained were processed in an Arburg (Registered Trade Mark) injection moulding machine of the Allrounder S100 type into rectangular test bars 150 x 6.5 x 3 mm. During processing the cylinder temperature was 185"C and the mould was at room temperature. The speed of the screw was 500 revolutions per minute. The injection pressure was 60 kg/cm2, the after-pressure 70 kg/cm2 and the total cycle time was 35 seconds.

Surprisingly, the polystyrene composition injection moulded in this manner was perfectly transparent and colourless. Even after exposure to daylight for one year, the injection moulded articles did not show any colouration. The Oxygen Index (OI) of the test bars produced was determined. The value found was 27.7. In a similar experiment without the addition of the fire-retardant compound used in accordance with the invention, the test bars were found to have an OI of 18.3.

Example X.

Fire-retardant polystyrene OI-bars were made in the manner described in Example V. In addition, UL-94 test bars were made. The following fire-retardant compounds to be investigated were incorporated into the polystyrene: A. 2,3-dibrornopropyl 2,4,6-triisopropyl benzene sulphonate with exclusively aliphatic bromine B. diester of bisphenol A with 2,4,6-triisopropyl benzene sulphonic acid with exclusively aromatic bromine, having the formula:

The results of the measurements are given in the following table.

TABLE 6

% by weight bromine in % by weight % by weight polymer Run compound A compound B composition OI UL 94 1 1.2 0.4 20.2 94HB 2 3.5 1.2 21.2 94VE-2 3 5.8 1.9 23.2 94VE-2 4 1.5 0.45 20.2 9411B 5 4.6 1.4 23.1 94VE-2 6 7.7 2.3 25.0 .94VE-2 From the results given in the above table it is clear that at the same percentage by weight of bromine in the polymer a higher OI is obtained with compound B than with compound A. Compound A begins to show distinct signs of decomposition at a temperture of 1700C, whereas with compound B decomposition begins at a temperature which is some twenty to thirty degrees higher.

Example XI.

The fire-retardant polystyrene was prepared in the manner described in Example V, except that the following compounds were used in accordance with the invention: a. 2,3,5,6-tetrabromo-p-tolyl 2,4,6-triisopropyl benzene sulphonate b. 2,4,6-tribromophenyl p-isopropyl benzene sulphonate c. 2,4,6-tribromophenyl 2,4-diisopropyl benzene sulphonate d. 2,4,6-tribromophenyl 2,5-diisopropyl benzene sulphonate e. pentabromophenyl 2,4,6-triisopropyl benzene sulphonate f. 2,4,6-tribromophenyl 2,4,6-triisopropyl benzene sulphonate g. 2,4,6-tribromophenyl p-toluene sulphonate The results are given in the following table.

TABLE 7

% by weight bromine in polystyrene composition Compound OI Ol Ol a 0.6 20.4 1.8 24.1 2.9 28.2 b 0.7 19;3 2 1 22.8 3.6 24.0 c 0.6 20.0 1.8 22.4 3.0 25.0 d 0.6 21.7 1.8 24.0 3.0 25.2 e 0.6 21.7 1.8 23.1 3.1 24.0 f 0.5 23.6 1.6 j 27.7 2.7 30:6 g 0.5 19.6 1.6 21.9 2.7 23.0 The results given in the above table show that at the same percentage of bromine the OI value is highest where R, = isopropyl and m = 3. It also appears that where q= l, the fire-retardant properties are optimal when n = 3 or 4.

WHAT WE CLAIM IS: 1. A fire retardant polymer composition which has a basis of polystyrene and which contains at least one compound of the general formula:

wherein q is I or 2 and when q = 1, then r = 0, l or 2, n = 3, 4 or 5, and r + n S 5, A is an alkyl group containing not more than 9 carbon atoms, and wherein when q = 2, then n = 2, 3 or 4, and when r = 0 the two structural units in the para position are directly interlinked or when r= 1 the two structural units in the para position are linked by an oxygen atom, an SO2 group or an isopropylidene group represented by A, and wherein further X is an NO2, Cl, Br,

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. a. 2,3,5,6-tetrabromo-p-tolyl 2,4,6-triisopropyl benzene sulphonate b. 2,4,6-tribromophenyl p-isopropyl benzene sulphonate c. 2,4,6-tribromophenyl 2,4-diisopropyl benzene sulphonate d. 2,4,6-tribromophenyl 2,5-diisopropyl benzene sulphonate e. pentabromophenyl 2,4,6-triisopropyl benzene sulphonate f. 2,4,6-tribromophenyl 2,4,6-triisopropyl benzene sulphonate g. 2,4,6-tribromophenyl p-toluene sulphonate The results are given in the following table. TABLE 7 % by weight bromine in polystyrene composition Compound OI Ol Ol a 0.6 20.4 1.8 24.1 2.9 28.2 b 0.7 19;3 2 1 22.8 3.6 24.0 c 0.6 20.0 1.8 22.4 3.0 25.0 d 0.6 21.7 1.8 24.0 3.0 25.2 e 0.6 21.7 1.8 23.1 3.1 24.0 f 0.5 23.6 1.6 j 27.7 2.7 30:6 g 0.5 19.6 1.6 21.9 2.7 23.0 The results given in the above table show that at the same percentage of bromine the OI value is highest where R, = isopropyl and m = 3. It also appears that where q= l, the fire-retardant properties are optimal when n = 3 or 4. WHAT WE CLAIM IS:

1. A fire retardant polymer composition which has a basis of polystyrene and which contains at least one compound of the general formula:

CN, OR2 or COOR2 group and R, and R2 may be the same or different and each represent a substituted or unsubstituted alkyl group having from 1 to 12 carbon atoms, or an acetyl or an allyl group, p and m each being 0 or an integer of from 1 to 3, and m + p rn+p < 5.

2. A fire retardant polymer composition which has a basis of a polyolefin and which contains at least one compound having the general formula:

wherein q is 1 or 2 and when q= 1, then r=0, 1 or 2,n=3,4 or 5, and r + n # 5, A is an alkyl group containing not more than 9 carbon atoms, and wherein when q = 2, then n = 2, 3 or 4, and when r = 0 the two structural units in the para position are directly interlinked or when r- 1 the two structural units in the para position are linked by an oxygen atom, an SO2 group or an isopropylidene group represented by A, and wherein further X is an NO2, Cl, Br,

CN, OR2 or COOR2 group and R, and R2 may be the same or different and each represent a substituted or unsubstituted alkyl group having from l to 12 carbon atoms, an acetyl group or an allyl group, p and m each being 0 or an integer of from 1 to 3, and m + p 6 5, provided that when q = 1 and r = 0, or when q = 2 at least one group R1 is a'substituted alkyl group having from 9 to 12 carbon atoms or at least one group X is an NO2

CN,OR2 or COOR2 groups.

3. A fire retardant polymer composition as claimed in claim 1 or claim 2 wherein the compound is 2,4,6-tribromophenyl p-2,3-dibromopropoxy benzene sulphonate.

4. A fire retardant polymer composition as claimed in claim l or claim 2 wherein the compound is 2,4,6 - tribromophenyl p - (2,2 - dichloro - 1,1 difluoroethoxy)benzene sulphonate.

5. A fire retardant polymer composition as claimed in claim 1 wherein the compound is 2,4,6-tribromophenyl p-dodecyl benzene sulphonate.

6. A fire retardant polymer composition as claimed in claim 1 or claim 2 wherein the compound is 2,3,4,5,6 - pentabromophenyl p - allyloxybenzene sulphonate.

7. A fire retardant polymer composition as claimed in claim 1 or claim 2 wherein the compound is 2,4,6-tribromophenyl p-acetoxybenzene sulphonate.

8. A fire retardant polymer composition as claimed in claim l or claim 2 wherein the compound is 2,4,6-tribromophenyl 2,4-dinitrobenzene sulphonate.

9. A fire retardant polymer composition as claimed in claim 1 or claim 2 wherein the compound is 2,4,6 - tribromophenyl 2 - chloro - 4 - carboxyethyl benzene sulphonate.

10. A fire retardant polymer composition as claimed in claim l or claim 2 wherein the compound is a diester of tetrabromobisphenol A with 2,4,6-triisopropyl benzene sulphonic acid.

11. A fire retardant composition as claimed in claim 1 wherein the compound is a diester of tetrabromobisphenol F with 2,4,6-trimethyl benzene sulphonic acid.

12. A fire retardant composition as claimed in claim 2 or claims 3,4,6,7,8 or 9 when appendant to claim 2 which comprises a polyethylene polymer.

13. A fire retardant composition as claimed in claim 2 or claims 3,4,6,7,8 or 9, when appendant to claim 2 which comrpises a polypropylene polymer.

14. A shaped article which is formed from a fire retardant polymer composition as claimed in any one of the preceding claims.

15. A fire retardant polymer composition as claimed in any one of the preceding claims wherein the compound has been prepared by reacting a compound of the formula:

wherein X, R1, m and p are as defined in claim 1 or claim 2 in an organic solvent with an alkaline solution of a compound of the general formula:

where A, n, r and q are as defined in claim l or claim 2, followed by isolating the compound having the general formula given in claim 1 or claim 2.

16. A fire retardant composition as claimed in claim 15 wherein the compound has been prepared by the process defined in claim 15 wherein the organic solvent is benzene or toluene and the alkaline solution is sodium hydroxide.

17. A fire retardant composition as claimed in claim 15 wherein the compound has been prepared by a process substantially as hereinbefore described with reference to Example I or Example II.

18. A fire retardant polymer substantially as hereinbefore described with reference to any one of Examples VI or VIII to XI.

19. A process for preparing a fire retardant polymer substantially as hereinbefore described with reference to any one of Examples VI or VIII to XI.