Methods and compositions for styrene inhibition via in situ generation of quinone methides
View Patent ↗Methods and compositions are provided for inhibiting the polymerization of a vinyl aromatic monomer, such as styrene monomer, during elevated temperature processing or distillation thereof or during storage or shipment of polymer containing product. The compositions include a combination of a hydroxybenzyl alcohol (1) and a dehydration catalyst (2). The combination is added to a vinyl aromatic monomer. Typically, the hydroxybenzyl alcohol is dehydrated in the styrene solution by the use of a strong acid catalyst acting as the dehydration catalyst, and the resultant reaction product is a quinone methide styrene inhibitor.
1. A composition for inhibiting the polymerization of a vinyl aromatic monomer comprising:
(1) a hydroxybenzyl alcohol; and
(2) a dehydrating catalyst.
2. A composition as recited in claim 1 wherein said (1) and (2) are present in an amount of about 1-99 wt % (1) 99-1 wt % (2).
3. A composition as recited in claim 2 , wherein the weight ratio of (1):(2) is about 2:1 to about 20:1.
4. A composition as recited in claim 1 , wherein said vinyl aromatic monomer is a member selected from the group consisting of styrene, bromostyrene, divinylbenzene, and α-methylstyrene.
5. A composition as recited in claim 1 wherein said dehydrating catalyst (2) is an acid chosen from i) alkyl, aryl, and alkylaryl sulfonic acids and ii) C 2 -C 36 saturated or unsaturated carboxylic acids.
6. A composition as recited in claim 5 wherein said dehydrating catalyst is an alkyl, aryl, or alkylaryl sulfonic acid.
7. A composition as recited in claim 1 , wherein said hydroxylbenzyl alcohol is di-tert butyl hydroxybenzyl alcohol.
8. A composition as recited in claim 1 wherein said dehydrating catalyst is dodecyl benzene sulfonic acid or para toluene sulfonic acid.
9. A composition as recited in claim 1 further comprising a 3) hydroxylamine compound wherein said hydroxylamine is present in an amount of 1-99 wt % based on the total weight of (1) and (2).
10. A composition as recited in claim 1 further comprising (4) a nitroxyl compound, said 4) being present in an amount of 1-99 wt % based on the total weight of (1) and (2).
11. A method for inhibiting the polymerization of a vinyl monomer comprising adding to said monomer (1) a hydroxybenzyl alcohol and (2) a dehydrating catalyst.
12. A method as recited in claim 11 wherein said (1) and (2) are present in an amount of about 1-99 wt % (1):99-1 wt % (2).
13. A method as recited in claim 11 wherein the weight ratio of (1):(2) is about 2:1 to about 20:1 and wherein about 10-10,000 ppm of said (1) and (2) combined is added to said vinyl monomer, based upon one million parts of said vinyl monomer.
14. A method as recited in claim 11 wherein said dehydrating catalyst is an acid chosen from i) alkyl, aryl, and alkylaryl sulfonic acids and ii) C 6 -C 22 saturated or unsecured carboxylic acids.
15. A method as recited in claim 11 wherein said hydroxylbenzyl alcohol is di-tert butyl hydroxylbenzyl alcohol.
16. A method as recited in claim 14 wherein said acid is dodecyl benzene sulfonic acid or para toluene sulfonic acid.
17. A method as recited in claim 11 further comprising adding to said vinyl monomer a (3) hydroxylamine compound, said hydroxylamine being added in an amount of about 1-10,000 ppm hydroxylamine based on 1 million parts of said vinyl monomer.
18. A method as recited in claim 11 further comprising adding to said vinyl monomer a (4) nitroxyl compound, said nitroxyl compound being added in an amount of about 1-10,000 ppm based on 1 million parts of said vinyl monomer.
19. A method for inhibiting the polymerization of a vinyl monomer comprising adding to said vinyl monomer an effective amount of the composition of claim 1 .
20. A method as recited in claim 19 wherein said composition comprises di-tertbutyl hydroxybenzyl alcohol and dodecyl benzene sulfonic acid or para toluene sulfonic acid.
21. A composition as recited in claim 1 wherein said hydroxylbenzyl alcohol has the formula
wherein R is H, or C 1 -C 10 alkyl, or C 6 -C 20 alkylaryl, R 1 and R 2 may or may not be present and are independently selected from C 1 -C 10 alkyl groups.
22. A method as recited in claim 11 wherein said hydroxylbenzyl alcohol has the formula
wherein R is H, or C 1 -C 10 alkyl, or C 6 -C 20 alkylaryl, R 1 and R 2 may or may not be present and are independently selected from C 1 -C 10 alkyl groups.