Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1992-11-03
1995-02-28
Yoon, Tae H.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
524288, 524296, 524412, 560 83, 560 87, C08K 503, C08K 310, C07C 6976
Patent
active
053938208
DESCRIPTION:
BRIEF SUMMARY
This invention relates to flame retardant compounds and compositions containing them.
Brominated organic compounds are well known to have flame retardant properties and are extensively used for this purpose in a wide variety of materials such as plastics and rubber, and including cellular and foamed materials such as foamed polystyrene and foamed polyurethanes.
The vapour phase mode of action of these compounds relies to a great extend on the thermal stability of the brominated compound in relation to that of the polymer. If the flame retardant compound has too low a thermal stability, i.e. begins to decompose or vaporise at too low a temperature, then it will be exhausted before the polymer itself starts decomposing. If the flame retardant has too high a thermal stability, it will remain in the condensed phase, and will therefore remain inactive as the polymer decomposes. Thus it is desirable to have a flame retardant compound whose thermal stability closely matches that of the polymer.
The thermal stability of various known flame retardants is given below, an accepted measure of thermal stability being the temperature in .degree.C. at which there is a 10% loss in weight; ("Thermal Characteristics of Polymer Materials", E A Turi, Academic Press, 1981):
______________________________________ 10% wt. loss at
______________________________________
decabromodiphenyloxide (DBDPO)
373.degree. C.
octabromodiphenyloxide (OBDPO)
340.degree. C.
bis (2-hydroxyethyl) ether of
337.degree. C.
tetrabromobisphenol A
octabromodiphenyl 336.degree. C.
______________________________________
Of these DBDPO has been extensively used as flame retardant in ABS (acrylonitrile-butadiene-styrene) rubbers and other similar engineering thermoplastics (ETP) that have a high thermal stability, e.g. high impact polystyrene (HIPS) and therefore require a high thermal stability flame retardant to match. ABS, for example, shows decomposition to 10% weight loss at about 390.degree. C. (Stanton Redcroft STA 1000, 10.degree. C. min..sup.-1 30 ml.min.sup.-1 air, sample weight 10.+-.0.02 mg. Inconel crucible). This figure is reasonably closely matched by that of DBDPO at 373.degree. C. However, the use of DBDPO has recently come into question, as it is suspected of forming highly toxic brominated dibenzo-dioxins and -furans upon pyrolsis, and these products have, indeed, been detected in the pyrolysis of polymer systems containing DBDPO.
Octabromodiphenyloxide has been substituted for DBDPO but is less effective as a flame retardant, and is also suspected of forming brominated dibenzo-dioxins and -furans upon pyrolysis.
In GB Patent No. 1341458, flame retardant benzene polycarboxylic esters of halogenated monohydric alcohols having a neopentyl-type configuration are disclosed, namely compounds of the formula. ##STR1## where R, R.sup.1 and R.sup.2 are halogenated methyl groups, X is halogen, n is 2 or 3, and m is 0-4, with the proviso that, when n is 2, the ester groups are in the meta or para-positions on the benzene ring, and when n is 3 (in which case m is correspondingly 0-3) the ester groups are in the 1, 3 and 5 positions. In other words, the compounds disclosed in GB1341458 are the halogenated neopentyl esters, especially the tribromoneopentyl esters of isophthalic acid, terephthalic acid and trimesic acid, and their halogenated derivatives.
In GB 1342458 attention is focused on esters, or iso- and terephthalic acid and of trimesic acid having aliphatic, rather than aromatic, halogenation, that is to say wherein the bromine or chlorine substituents are in the aliphatic side chains rather than in the aromatic ring. Aromatic substitution is embraced within the broad formula, but only one working example is given, namely the preparation of the compound di[2,2 bis(bromo-methyl)-3-bromopropyl] tetrachloroterephthalate, or, in accordance with the trivial, rather than systematic, nomenclature used herein: bis-(tribromoneopentyl)tetrachloroterephthalate. There is no exemplification of any compounds having brominated aromat
REFERENCES:
patent: 3772342 (1973-11-01), Foley et al.
patent: 4376837 (1983-03-01), Jenkner et al.
Ashworth Paul
Schneider Michael J.
The Associated Octel Company Limited
Yoon Tae H.
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