Diol compositions

A polyol composition consisting essentially of a homogeneous liquid or low melting solid admixture of propylene glycol and a diol obtained by alkoxylating a propylene glycol dispersion of 3,3',5,5' tetrabromobisphenol A with ethylene oxide, propylene oxide or mixtures thereof. These polyol compositions are useful in preparing fire and chemical resistant thermosetting resinous compositions.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to diol compositions. 
2. Description of the Prior Art 
Thermosetting polyester resinous compositions comprising solutions of an 
essentially linear unsaturated polyester in a vinyl monomeric crosslinking 
agent, e.g., styrene, are extensively utilized to prepare molded or cast 
thermoset plastic articles. The indicated linear polyesters are obtained 
by condensing an .alpha.,.beta.-ethylenically unsaturated dicarboxylic 
acid as all or part of the diacid component with a glycol. The bulk of the 
glycols used for this purpose is propylene glycol. 
Where it is desired to impart fire and chemical resistance to the 
polyester, a halogenated diacid and/or a halogenated diol is generally 
incorporated into the polyester structure for optimum results. A 
particularly preferred halogenated compound useful for this purpose is the 
diol obtained by alkoxylating 3,3',5,5' tetrabromobisphenol A. In 
accordance with the prior art, the alkoxylation reaction is carried out in 
an inert solvent which is removed upon completion of the reaction to 
provide the compound as a high melting solid which is sold as a powder or 
solid melt. Removal of the solvent in this manner is costly and moreover 
provides a product which is difficult to handle in connection with its use 
to prepare linear polyester resins. 
SUMMARY OF THE INVENTION 
In accordance with this invention, diol compositions are provided by 
reacting a propylene glycol dispersion of 3,3',5,5' tetrabromobisphenol A 
with at least a stoichiometrical amount based on said phenolic compound of 
ethylene oxide, propylene oxide or mixtures thereof. Conventional 
alkoxylation reaction conditions apply resulting in essentially complete 
preferential addition of the alkylene oxide to the phenolic hydroxy groups 
present. 
DESCRIPTION OF THE PREFERRED EMBODIMENT 
Bisphenol A, the starting material in the practice of this invention, is a 
commodity chemical prepared by condensing phenol with acetone. The 3,3', 
5,5' tetrabromobisphenol A derivative is likewise commercially available 
and a representative product will be identified in the working example to 
follow. The indicated bromo derivative is dispersible in propylene glycol 
and, accordingly in preparing the diol compositions of this invention, the 
tetrabromobisphenol A is first dispersed in said glycol prior to effecting 
the alkoxylation thereof. Applicable dispersions of this type are composed 
of said glycol and the brominated bisphenol A in the weight ratio of from 
1:19::1:2, respectively. A more preferred range of ratios for the 
utilitarian purposes contemplated herein is from about 1:9::1:4, 
respectively. 
The glycol dispersion of the tetrabromobisphenol A is reacted with the 
alklyene oxide under conditions normally observed in an adduction reaction 
of this type. These conditions include a temperature of from 50.degree. C. 
to 200.degree. C. and more preferably from about 100.degree. C. to 
150.degree. C. Pressure conditions are in the order of from 0.5 to 14 
atmospheres. However, a preferred range of pressure is from about 3 to 6 
atmospheres corresponding to the autogenous pressures developed when 
observing a reaction temperature with the preferred range. Conventionally, 
a basic catalyst is employed to facilitate the reaction. Strong bases such 
as the alkali metal hydroxides, sodium methylate and the like are 
particularly suitable. 
As previously indicated, the preferred alkylene oxides useful in the 
practice of this invention are propylene oxide and ethylene oxide. 
Mixtures of these oxides are likewise applicable. The preferred ratio of 
the alkylene oxide to the tetrabromobisphenol A is about stoichiometrical; 
i.e., 2-2.2 moles of the alkylene oxide per mole of said phenol. Higher 
ratios of alkylene oxide can be employed. However, when the 
stoichiometrical amount is substantially exceeded there is the likelihood 
of producing a diol which may not be considered as the most desirable in 
preparing linear polyesters of optimum rigidity, chemical and/or fire 
resistance. 
The end point of the alkoxylation reaction can be conveniently determined 
by noting when the reaction pressure completely subsides. In the situation 
where a stoichiometrical amount of the alkylene oxide is observed, the 
completion of reaction is indicated by a nil acid value upon completion of 
the reaction. The product is discharged from the reactor, cooled and then 
can be used as such in the formulation of linear polyesters suitable for 
use for formulating thermosetting polyester resinous compositions. There 
is no need here to go into any details regarding the preparation of such 
polyesters or their use in formulating the indicated thermosetting 
compositions since this area of technology is highly developed and 
abundantly documented in the patent art.

For the purpose of illustrating the best mode contemplated for practicing 
the present invention, the following working example is given. All parts 
and percentages set forth are parts by weight unless otherwise indicated. 
EXAMPLE I 
Into a suitable pressure reaction vessel were charged 546 parts of 
tetrabromobisphenol A (BA-50; Great Lakes Chemical Corp.), 276 parts 
propylene glycol and 7.3 parts of alcoholic potassium hydroxide containing 
25% active. Ethylene oxide in the amount of 97 parts were added at 
105.degree.-115.degree. C., providing a pressure of about six atmospheres 
maximum. The ethylene oxide was allowed to react at the temperature 
conditions noted until there was no detectable acid value. The product was 
discharged from the reaction vessel and exhibited a hydroxyl value of 540. 
The product was a clear liquid at room temperature.