Polymerization of 2-pyrrolidone with alkaline catalyst and SO.sub.2 chain initiator
AssigneeBarson Corporation
InventorsArthur C. Barnes, Carl E. Barnes
Life of this patent
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Abstract
A method of forming white polymers of controlled molecular weight when polymerizing 2-pyrrolidone using an alkaline catalyst and sulfur dioxide as the chain initiator is disclosed. The temperature at which the polymerization is carried out is critical and is carefully controlled. The SO.sub.2 which must also be controlled within limits is diluted with an inert gas to diminish its activity and make it easier to measure the small amounts involved. The viscosity and thermal stability of the polymers formed are as good as or better than those formed when CO.sub.2 is used as the initiator.
Claims15
A process for the polymerization of 2-pyrrolidone comprising the polymerization of substantially anhydrous monomeric 2-pyrrolidone at a temperature of from 30.degree. to 45.degree. C. in the presence of a primary catalyst and an activator consisting essentially of sulfur dioxide, the concentration of sulfur dioxide varying with the temperature used and not exceeding a sulfur dioxide concentration bounded by an approximate straight line drawn on a semi-log graph having a logarithmic scale of sulfur dioxide concentration along the ordinate in terms of mols of sulfur dioxide per mol of 2-pyrrolidone monomer and having polymerization temperature along the abscissa, said line being drawn on said graph from the vicinity of the point at 30.degree. C. temperature and 0.024 mols of sulfur dioxide per mol of monomer to the vicinity of the point at 45.degree. C. temperature and 0.004 mols of sulfur dioxide per mol of monomer, the sulfur dioxide concentration being at least about 0.002 mols of sulfur dioxide per mol of pyrrolidone monomer with the polymerization taking place at a substantially constant temperature, whereby the polypyrrolidone formed is of a viscosity capable of being melt spun.
A process for the polymerization of 2-pyrrolidone comprising the steps of contacting monomeric 2-pyrrolidone with a compound selected from the group consisting of an alkali metal hydroxide, a quaternary ammonium hydroxide, and an alkali metal alcoholate, removing the water formed or the alcohol formed in the reaction to yield a substantially anhydrous solution of the corresponding salt of 2-pyrrolidone as the primary catalyst in 2-pyrrolidone, contacting the mixture with an activator consisting essentially of sulfur dioxide and carrying out the polymerization at a temperature between 30.degree. and 45.degree. C., the concentration of sulfur dioxide varying with the temperature used and not exceeding a sulfur dioxide concentration bounded by an approximate straight line drawn on a semi-log graph having a logarithmic scale of sulfur dioxide concentration along the ordinate in terms of mols of sulfur dioxide per mol of 2-pyrrolidone monomer and having polymerization temperature along the abscissa, said line being drawn on said graph from the vicinity of the point at 30.degree. C. temperature and 0.024 mols of sulfur dioxide per mol of monomer to the vicinity of the point at 45.degree. C. temperature and 0.004 mols of sulfur dioxide per mol of monomer, the sulfur dioxide concentration being at least about 0.002 mols per mol of pyrrolidone monomer, the polymerization of pyrrolidone taking place at a substantially constant temperature, whereby the polypyrrolidone formed is of a viscosity capable of being melt spun.
A process for the polymerization of 2-pyrrolidone comprising the polymerization of substantially anhydrous monomeric 2-pyrrolidone at a temperature of from 30.degree. to 45.degree. C. in the presence of a primary catalyst and an activator consisting essentially of sulfur dioxide, said temperature being maintained at a substantially constant temperature within plus or minus 2.degree. C., the concentration of sulfur dioxide varying with the temperature used and not exceeding a sulfur dioxide concentration bounded by an approximate straight line drawn on a semi-log graph having a logarithmic scale of sulfur dioxide concentration along the ordinate in terms of mols of sulfur dioxide per mol of 2-pyrrolidone monomer and having polymerization temperature along the abscissa, said line being drawn on said graph from the vicinity of the point at 30.degree. C. temperature and 0.024 mols of sulfur dioxide per mol of monomer to the vicinity of the point at 45.degree. C. temperature and 0.004 mols of sulfur dioxide per mol of monomer, the sulfur dioxide concentration being at least about 0.002 mols per mol of pyrrolidone monomer, whereby the polypyrrolidone formed is of a viscosity capable of being melt spun.
Dependencies are inferred from the claim text.