Inverse interfacial polymerization for preparing certain halogenated aromatic polyesters
AssigneeCelanese Corporation
InventorsMichael M. Besso, Lowell Saferstein
Life of this patent
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Abstract
The present invention relates to a process for preparing certain halogenated aromatic polyesters by an inverse interfacial polymerization technique. More specifically, the present invention offers a method for substantially reducing the amount of low molecular weight fraction which accompanies the formation of these polyesters when prepared by standard interfacial polymerization techniques by (1) inverting the order of addition of one phase to the other, i.e. by adding the aqueous phase to the organic phase, (2) controlling the rate of addition of the aqueous phase to the organic phase and (3) adding the catalyst to the organic phase prior to the addition of the aqueous phase thereto.
Claims23
A process for preparing a halogenated aromatic polyester of the recurring structural formula ##STR6## where X which may be the same or different is chlorine or bromine, Y which may be the same or different is hydrogen, chlorine or bromine, R and R' may be the same or different and represent lower alkyl groups, hydrogen, or together constitute a cyclic hydrocarbon group, and n equals at least 13, by the inverse interfacial polymerization of a halogenated bisphenol and isophthaloyl chloride, terephthaloyl chloride or mixtures thereof which comprises:
- I. providing an organic phase comprising
- a. an organic solvent,
- b. a phthaloyl chloride or mixtures thereof, and
- c. a catalytic amount of a phase transfer catalyst;
- Ii. providing an aqueous phase comprising
- a. an aqueous solvent immiscible with said organic solvent and capable of dissolving an alkali salt of said halogenated bisphenol,
- b. an alkali salt of said halogenated bisphenol, and
- c. a base in amounts sufficient to provide a pH of at least 8 in said aqueous solution,
- Iii. adding the aqueous phase to the organic phase over a period of time of not less than about 20% of the total polymerization time and in a manner sufficient to sustain the uniform availability of phase transfer catalyst for reaction with the alkali salt of the bisphenol during the polymerization reaction thereby providing a polyester having a low molecular weight fraction of not greater than about 3% by weight of the polyester;
- Iv. recovering the resulting polyester product.
A process for preparing a halogenated aromatic polyester of the recurring structural formula ##STR7## where X which may be the same or different is chlorine or bromine, Y which may be the same or different is hydrogen, chlorine or bromine, R and R' may be the same or different and represent lower alkyl groups, hydrogen, or together constitute a cyclic hydrocarbon group, n equals at least 13, by the inverse interfacial polymerization of a halogenated bisphenol and a mixture of isophthaloyl chloride, and terephthaloyl chloride which comprises:
- I. providing an organic phase comprising
- a. an organic solvent,
- b. a mixture of isophthaloyl and terephthaloyl chloride, and
- c. a catalytic amount of a phase transfer catalyst,
- Ii. providing an aqueous phase comprising
- a. water,
- an alkali salt of said halogenated bisphenol, and
- c. a base sufficient to establish a pH of said aqueous phase of at least 8;
- Iii. gradually adding the aqueous phase to organic phase over a period of time of about 20 to 30% of the total polymerization time and in a manner sufficient to provide a stoichmetric excess of acid chloride over the alkali salt of the bisphenol in the reaction mixture during the polymerization said stoichiometric excess being sufficient to sustain the uniform availability of the phase transfer catalyst for reaction with the alkali salt of the bisphenol thereby providing said aromatic polyester with a low molecular weight fraction of not greater than 3% by weight of the total weight of the polyester formed;
- and
- Iv. recovering the resulting polyester product.
A process for preparing a brominated aromatic polyester of the recurring structural formula ##STR8## wherein X and Y are bromine, R and R' may be the same or different and represent lower alkyl groups, hydrogen, or together constitute a cyclic hydrocarbon group, and n equals at least 13, by the inverse interfacial polymerization of a brominated bisphenol and a mixture of isophthaloyl chloride and terephthaloyl chloride which comprises
- I. providing an organic phase comprising
- a. methylene chloride,
- b. a 60:40 mixture of isophthaloyl and terephthaloyl chloride,
- c. a catalytic amount of benzyltriethylammonium chloride;
- Ii. providing an aqueous phase comprising
- a. water,
- b. an alkali salt of said brominated bisphenol,
- c. sodium hydroxide in an amount sufficient to establish a pH of said aqueous phase of at least 8;
- Iii. gradually adding the aqueous phase to the organic phase at a rate of about 1 to about 10 mole percent per minute based on the total number of moles of the bisphenol salt originally present in the aqueous phase prior to addition;
- Iv. recovering the resulting polyester product.
Dependencies are inferred from the claim text.