Polymer inhibition of vinyl aromatic monomers using a quinone methide/alkyl hydroxylamine combination
The invention provides a composition of matter and a method of its use in preventing unwanted polymerization reactions. The composition comprises an inhibitor and a retarder. The inhibitor is highly effective. The retarder is reliable under extreme and emergency situations. The inhibitor can be an alkylhydroxylamine. The retarder can be a 7-cyano-quinone methide. The combination of the inhibitor and retarder has been found to be far more effective than expected.
1. A method for inhibiting the premature polymerization of monomers by adding to said monomers an effective amount of a composition comprising at least one inhibitor and at least one retarder wherein the inhibitor is an alkylhydroxylamine and the retarder is a 7-substituted-quinone methide selected from the group consisting of: 2,6-di-t-butyl-7-cyano quinone methide, 2,6-di-t-butyl-7-methoxycarbonyl quinone methide, and any combination thereof.
2. The method of claim 1 in which the monomers are vinyl aromatic monomers.
3. The method of claim 1 further comprising an additional inhibitor selected from the group consisting of hydroxypropylhydroxylamine, diethylhydroxylamine, and any combination thereof.
4. The method of claim 1 in which the retarder is non-toxic.
5. The method of claim 1 wherein the inhibitor has a dosage of between 1 to 200 ppm, based on the weight of the monomer.
6. The method of claim 1 wherein the retarder has a dosage of between 1 to 1200 ppm, based on the weight of the monomer.
7. The method of claim 1 in which the inhibitor and retarder are added separately to the monomer.
8. The method of claim 1 in which the amount of inhibitor in the presence of the monomers is maintained at a relatively constant amount by adding the inhibitor in increments over time.
9. The method of claim 1 in which the monomers are in a processing stage.
10. The method of claim 8 in which the inhibitor is added continuously.
11. The method of claim 1 in which the monomers are in solution and the inhibitor is continuously dispersed throughout the solution.
12. The method of claim 1 in which the monomer is at a temperature of between 60 and 180 degrees Celsius.
13. The method of claim 1 in which the monomers are in a manufacturing stage.
14. The method of claim 1 further comprising the step of adding tertiary-butylcatechol, the tertiary-butylcatechol functioning as an inhibitor during storage and transport.
15. The method of claim 14 further comprising the steps of removing the tertiary-butylcatechol, and producing polystyrene from the monomers.
16. A method for inhibiting the premature polymerization of monomers by adding to said monomers an effective amount of a first composition comprising at least one inhibitor and at least one retarder wherein the inhibitor is an alkylhydroxylamine and the retarder is a second composition comprising 2,6-di-t-butyl-7-carboxy quinone methide.