GB2164051A - Flame retardant telomers - Google Patents

Abstract

Telomers of the formula: <IMAGE> wherein R<1> is H or lower alkyl or a fragment of an initiator, <IMAGE> and/or <IMAGE> Hal is bromine or chlorine, n is an integer of 1 to 4, x is an integer from 1 to 20, y and z each designate independently 0 or an integer of 1 to 200, at least one of them being different from zero; m is an integer of 1 to 4, R<2> is -H, lower allyl or halogen, with the stipulation that when m is 3 or 4, two of the -OH groups are attached to other parts of the molecule, are of value in imparting flame retarding properties. They are prepared by telomerising a halogenated styrene with a diene, e.g. in the presence of hydrogen peroxide, and optionally halogenating double bonds in the telomer. They are used as a component in the manufacture of polyurethanes.

Description

SPECIFICATION Fire retardant compounds Field of the invention This invention relates to new compounds which are halogen-containing telomers, co-telomers and low molecular weight polymers, to a process for their production and flame retardant polymers containing them The novel products of the invention are valuable in imparting flame retardent properties to polymers and especially to polyurethanes.

Prior art High molecular weight copoiymers of styrene and isoprene, acrylonitrile and butadiene are well established in industry and are produced in large tonnage (Encyclopedia of Polymer Science and Technology, H.F. Mark, N.G. Gaylord and M.M Bikales, Eds., Interscience, 1965).

Low molecular weight hydroxy-terminated polybutadienes are also known. Reactive intermediates of this type having carboxyl or amine end groups are also used in polymeric systems such as polyurethanes, polyesters and epoxides.

The above-mentioned materials are inflammable and thus lack practicality for non-inflammable applications. In order to form effective flame retarding compositions it is essential that the material should contain substantial amounts of a flame retarding monomer component.

Summary ofthe invention The present invention provides compounds which are halogen-containing telomeric and low molecular weight polymers of the general average formula:

wherein R1 is H or lower alkyl e.g. containing 1 to 4 carbon atoms, or a fragment of an initiator, -Q- is selected from

Hal is bromine or chlorine, n is an integer of 1 to 4, xis an integer from 1 to 20, y and z each designate independently 0 or an integer of 1 to 200, at least one of them being different from zero; m is an integer of 1 to 4, R2 is -H, lower alkyl, e.g. containing 1 to 4 carbon atoms, or halogen, with the stipulation that when m is 3 or 4, two of the -OH groups are attached to other parts of the molecule.

The preferred compounds of the invention are co-telomers containing bromine and/or chlorine, prepared frqm a monomer which contains a high percentage of halogen and a second monomer which is a diene.

According to a preferred embodiment, the first monomer is a halogenated, preferably brominated styrene, with one to four bromine atoms in the aromatic ring; the second monomer being a diene such as butadiene, isoprene, chloroprene or the like.

The co-telomers of the invention are advantageously hydroxy-group terminated, containing an average of two hydroxy groups per molecule.

The compounds of the invention are the product of reaction of two monomers, namely monomer A which contains a high proportion of halogen, and a second monomer, B, which is a diene. The preferred monomer A is a halogenated styrene, preferably poiybrominated styrene. The preferred monomer B is butadiene, isoprene or chloroprene. The preferred products are hydroxy terminated, and thus contain on the average at least two hydroxy groups per molecule. The process of production may lead to products which contain on the average slightly less or more than two hydroxy groups per molecule. Such deviations from bifunctionalitywith respectto the hydroxy groups does not restrict the utility of the products. In the compounds of the invention the moiety Q preferably comprises from about 10 to about 30 weight percent of the compound.

The synthesis is based on the reaction between the two monomers in solution or emulsion in the presence of a peroxide, e.g. hydrogen peroxide e.g. in an organic solvent, with or without a catalyst and with or without an initiator. The reaction is preferably carried out art a temperature from 0 up to about 1 50 C, particularly from ambient e.g. 1 5"C up to 150 C. The surprising feature of the present invention is in the extreme ease at which the monomers react to uniquely produce a low molecular weight co-telomer while hydrogen peroxide serves as both the initiator and the telogen.It is also possible to control the amount of halogen in the final product composition by changing the initial ratio of bromostyrene to butadiene in the feed, thus altering the properties of the co-telomer. The co-telomers are semi-liquids, white-transparent in appearance. These co-telomers dissolve in organic solvents such as toluene, chloroform ortetrahydrofuran (THF).

The co-telomers of the invention are generally in the range of from a molecular weight of 600 to about 14,000. By further halogenation of the products of the invention, at the double bonds, a higher halogen content is obtained, and the thus introduced aliphatic halogens further enhance the fire-retardent properties of compositions containing such co-telomers.

Co-telomers of the invention are very useful products. Most are liquid or semi-solids at ambient temperature, and can be used as components of flame retardent polymers and especially polyurethane. This is accomplished by coupling these co-telomers with a di- or tri-isocyanate component comprising the polyurethane system, as is usually being practised in the art. The elastomeric part of the co-telomer may be used to impart elasticity and to enhance the toughness of polymeric compositions. The flame-retardancy of these co-telomers may be further enhanced by using chloroprene as the diene constituent, or by post bromination, chlorination or bromo-chlorination of the double bonds contained in them.

It is well-known that in many cases, and particularly in the case of polyurethane compositions, the presence of "aliphatic" halogens are desirable in view of their being split-off at a lower stage of the burning process, thus more effectively restraining the process of combustion. In order to form effective flame retarding diols or polyols we use a flame-retarding monomer component such as a brominated styrene component. The high content of bromine in this comonomer, on the one hand, and the final co-telomers being liquid or semi-liquid on the other, comprise a novel and unexpected feature. Only in this physical state may they be useful in the construction of foamed or elastomeric materials. Surprisingly, we found that such compositions may be obtained according to the present process, which allows for the synthesis of these novel materials.

Description ofthe drawings Figure 1 of the accompanying drawing shows the nuclear magnetic resonance spectrum of a compound of the invention.

The following Examples describe the synthesis and the nature of the novel compounds.

Example 1 4.04g Monobromostyrene and 0.10 g sodium dodecyl sulphate (SDS) are added to 10 ml toluene in a thick wall glass ampoule. 3.40 g Hydrogen peroxide (30%) are then added. The ampoule, fitted with a stopcock, is cooled in dryice/isopropanol or liquid nitrogen. Butadiene is condensed into the ampoule. Excess butadiene is cautiously boiled off so that 3.13 g butadiene are left inside the ampoule. The ampoule is cooled and sealed. The sealed ampoule is placed in a holder inside an oven fitted with a rotating arm. At the end of the reaction the ampoule is cooled again and opened.

The content of the ampoule is poured into excess of methanol. Volatiles are removed by pumping out at 0.2 mm Hg and ambient temperature to a constant weight. Conditions: 98"C, varied amountoftime. About 80% conversion is reached after 24 hours. NMR of the new co-telomer is shown in Figure 1 and some characteristic properties of this co-telomer are shown in Table 1.

TABLE 1 Characteristics of co-telomer in Example 1 Bromine content (w/w, %) Feed 24.6 Product 20.1 Vinyl content (% of butadiene content) 18 Hydroxy number 1.93 Molecularweight 1120 Tg ("C) -45 Example 2 The procedure of Example 1 is repeated but with variations as indicated below to give a co-telomer of characteristics set out in Table 2-below.

Butadiene 2.84 9 Bromostyrene 2.39 g Hydrogen Peroxide (30%) 3.13 9 Toluene 10 my Emulsifier (SDS) 0.1 9 Conditions: 98"C, 24 hours TABLE 2 Characteristics of co-telomer in Example 2 Bromine content (w/w%) Feed 20.0 Product 19.2 Vinyl content (%) 24.0 Hydroxyl number 2.66 Molecular weight 2330 Tg ("C) -34 Example 3 The procedure of Example 1 is repeated but with variations as indicated below to give a co-telomer of characteristics set out in Table 3.

Butadiene 6.109 Bromostyrene 4.70 9 Hydrogen peroxide (30%) 5. 00 9 Toluene 20 ml Emulsifier 0.2 g Procedure: The ampoule with the above formulation is not sealed but rather, is placed in an autocloave with magnetic stirring instead of in a rotating holder.

Conditions: 100 C,24 hours TABLE 3 Characteristics of co-telomer in Example 3 Bromine content (w/w%) Feed 19.0 Product 18.0 Vinyl content (%) 24.4 Hydroxyl number 2.58 Molecular weight 1680 Tg ("C) -45 Example 4 The procedure of Example 1 is repeated but with variations as indicated below to give a co-telomer of characteristics set out in Table 4 below.

Butadiene 6.54 9 Bromostyrene 6.37 g Hydrogen peroxide (30%) 57.009 Toluene 29 ml Emulsifier 0.2 9 The bromostyrene in this Example is a mixture of monobromostyrene and dibromostyrene which yields 50% bromine in the mixture.

Conditions: 100 C,24 hours TABLE 4 Characteristics of co-telomer in Example 4 Bromine content (w/w%) Feed 24.7 Product 24.8 Vinyl content (%) 28.6 Hydroxyl number 3.37 Molecular weight 1920 Tg ("C) -14 Example 5 The procedure of Example 3 is repeated but with variations as indicated below to give a co-telomer of characteristics set out in Table 5 below.

Butadiene 5. 19 g Bromostyrene 4. 53 9 Hydrogen peroxide (30%) 5. 92 9 Toluene 20 ml Emulsifier 0.50 9 The bromostyrene in this Example is tribromostyrene.

Conditions: 100 C,24 hours TABLE 5 Characteristics of co-telomer in Example 5 Bromine content (w/w%) Feed 32.8 Product 35.2 Vinyl content (%) 24.7 Hydroxyl number 2.72 Molecular weight 4430 Tg ("C) 1.3 Example 6 1.00 g of the material prepared according to Example 3 (bromine content 22.3%) is dissolved at ambient temperature in 50 ml chloroform in a flask. 0.71 g bromine is dissolved in 50 ml chloroform and added dropwise while stirring with a magnetic stirrer during 2 hours.

The solution is stirred for another 2 hours. The product was precipitated in methanol and dried in a vacuum chamber at room temperature to a constant weight. Yield: 1.50 g (87.7% yield). Bromine content: 52.7% Tg = 52.3"C.

Example 7 5 g co-telomer synthesised in Example 2 is dissolved in 10 g toluene and added to 2.5 g component B of polyurethane. The mixture was added to 2.5 g component A and stirred with magnetic stirrer for half an hour. The product is dried in an oven at 100 C for half an hour and under vacuum at ambient temperature for 20 hours. A new composition of polyurethane is formed. The product does not have a Tg between -100"C to 250 "C and is stable in this range of temperatures.

Claims (12)

1. Compounds ofthe general average formula:

wherein R1 is H or lower alkyl, or a fragment of an initiator, -Q- is

Hal is bromine or chlorine, n is an integer of 1 to 4, xis an integer from 1 to 20, y and z each designate independently 0 or an integer of 1 to 200, at least one of them being different from zero; m ig an integer of 1 to 4, R2 is -H, lower alkyl or halogen, with the stipulation that when m is 3 or 4, two of the -OH groups are attached to other parts of the molecule.

2. A compound according to claim 1 wherein the unsaturated moieties are derived from butadiene, isoprene or chloroprene.

3. A compound according to claim 1 or 2, wherein the moiety Q comprises from about 10 to about 30 mole percent of the compound.

4. A compound according to any one of the preceding claims having an average of at least two hydroxy groups. per molecule.

5. A compound according to any one of the preceding claims having a molecular weight of 600 to about 14,000.

6. A compound according to claim 1 substantially as hereinbefore described with reference to any one of Examples 1 to 6.

7. A process for the production of a compound as defined in any one of the preceding claims, which comprises reacting a halogenated styrene compound with a diene in solution or emulsion in the presence of a suitable peroxide, optionally in the presence of an initiator or catalyst, and if desired halogenating the double bond in Q.

8. A process according to claim 7, wherein the peroxide is hydrogen peroxide of a concentration from 2 to 70% by weight in aqueous solution.

9. A process according to claim 7 or 8, wherein the reaction is effected in a solvent which is toluene, chloroform ortetrahydrofuran, at a temperature from 0 C and up to about 150"C.

10. A process according to claim 7 substantially as hereinbefore described in any one of Examples 1 to 6.

A A polyurethane containing a compound as claimed in any one of claims 1 to 6.

12. Polymeric compositions rendered flame retardant by the incorporation of a compound as claimed in any one of claims 1 to 6.