POLYMERIZATION INHIBITOR FOR VINYL-CONTAINING MATERIALS

Abstract: This invention relates to a process of inhibiting the polymerization of vinyl-containing materials through the use of an effective amount of a polymerization inhibitor comprising quinone diimide and a nitroxyl stable free radical under various conditions. This invention also relates to the polymerization inhibitor composition.

Description: The quinone diimide compound of the present invention comprises a benzoquinonediimide compound. The benzoquinonediimide compound typically has the general formula: wherein R 1 and R 2 are the same or different and are alkyl, aryl, alkaryl, or aralkyl groups. Preferably the benzoquinonediimide compound is selected from the group consisting of N,N'-dialkyl-p-benzoquinonediimides and N-phenyl-N'-alkyl-p- benzoquinonediimides. The benzoquinonediimide compound may also be selected from the group consisting of N.N'-di-sec-butyl-p-benzoquinonediimide, N- phenyl-N'-methyl-p-benzoquinonediimide, N-phenyl-N'-ethyl-p- benzoquinonediimide, N-phenyl-N'propyl-p-benzoquinonediimide, N-phenyl-N'-n- butyl-p-benzoquinonediimide, N-phenyl-N'-isobutyl-p-benzoquinonediimide, N- phenyl-N'-sec-butyl-p-benzoquinonediimide, N-phenyl-N'-tert-butyl-p- benzoquinonediimide, N-phenyl-N'-n-pentyl-p-benzoquinonediimide, N-phenyl-N'- (l-methylhexyl)-p-benzoquinonediimide, and N-phenyl-N'-(1 ,3-dimethyIhexyl)-p- benzoquinonediimide. A preferred benzoquinonediimide compound comprises N-{4-[(1 ,3- dimethylbutyl)imino]-2,5-cyclohexadien-1-ylidine}, also named [4-(1 ,3-dimethyl- butylimino)-cyclohexa-2,5-dienylidene]-phenyl-amine, and which is available from Flexsys under the product names Q-Flex QDI and 6-QDI. In the vinyl functionality polymerization inhibitor of the present invention the ratio of quinone diimide to the at least one of the stable free radical compound and hydroquinone can range by weight in a ratio of from about 1 :20 to about 20:1 , preferably of from about 1 :10 to about 10:1 , more preferably of from about 1 :3 to about 3:1 , more preferably of from about 1 :1. The present invention also relates to a method for inhibiting the polymerization of compositions comprising vinyl functionality comprising adding to the compositions comprising vinyl functionality an effective amount of the vinyl functionality polymerization inhibitor. The compositions comprising vinyl functionality may be selected from the group consisting of vinyl chloride, vinyl acetate, methylmethacrylate, acryionitrile, methacrylonitrile, acrylic acid, methacrylic acid, styrene, -methylstyrene and vinyltoluene. The present invention also relates to compositions comprising the compositions comprising vinyl functionality and the vinyl functionality polymerization inhibitor. Detailed Description of the Invention The present invention relates to a method for inhibiting the undesired polymerization of compositions comprising vinyl functionality. The compositions comprising vinyl functionality are characterized by having a CH 2 =CH- group and are highly reactive and polymerize easily. Examples of such compositions comprising vinyl functionality include vinyl monomers such as vinyl chloride, vinyl acetate and similar unsaturated esters; methylmethacrylate, acryionitrile, methacrylonitrile, acrylic acid, methacrylic acid and their esters and amides, styrene, α-methylstyrene, vinyltoluene. Preferably, the compositions comprising vinyl functionality comprises vinyl monomers selected from the group consisting of vinyl chloride, vinyl acetate, methylmethacrylate, acryionitrile, methacrylonitrile, acrylic acid, methacrylic acid, styrene, α-methylstyrene and vinyltoluene. Preferably the invention relates to a process for inhibiting the polymerization of monomers comprising vinyl functionality, such as acryionitrile or styrene. The compositions may be a composition which contains vinyl functionality such as an oligomer or, more preferably, the composition which contains vinyl functionality is a vinyl monomer. For the purposes of this invention, the term "effective amount" refers to the amount of a vinyl polymerization inhibitor necessary to retard or inhibit the polymerization of the composition which contains vinyl functionality as determined by an increase in the length of the induction period for the presence of polymer under a set of conditions which would typically be conducive of polymerization. This amount will vary according to the conditions under which the composition that contains vinyl functionality is subject during its processing, handling and/or storage The quinone diimide of use in vinyl polymerization inhibitors of the present invention may be any quinone diimide. Preferably, the quinone diimide of the present invention is a benzoquinonediimide compound. The benzoquinonediimide compound of use in the present invention is described in U.S. Patent No. 5,562,863, the disclosure of which is incorporated in its entirety by reference. The benzoquinonediimide has the general formula: wherein R. and R 2 are the same or different and are alkyl, aryl, alkaryl, or aralkyl groups. Preferably, these groups have one to about 20 carbon atoms and the alkyl groups can be straight-chained, branch-chained, or cyclic groups. The benzoquinonediimide compound may be selected from the group consisting of N,N'-dialkyI-p-benzoquinonediimides and N-phenyl-N'-alkyl-p- benzoquinonediimides. The benzoquinonediimide compound may also be selected from the group consisting of N,N'-di-sec-butyl-p-benzoquinonediimide, N- phenyl-N'-methyl-p-benzoquinonediimide, N-phenyl-N'-ethyl-p- benzoquinonediimide, N-phenyl-N'propyl-p-benzoquinonediimide, N-phenyl-N'-n- butyl-p-benzoquinonediimide, N-phenyl-N'-isobutyl-p-benzoquinonediimide, N- phenyl-N'-sec-butyl-p-benzoquinonediimide, N-phenyl-N'-tert-butyl-p- benzoquinonediimide, N-phenyl-N'-n-pentyl-p-benzoquinonediimide, N-phenyl-N'- (l-methylhexyl)-p-benzoquinonediimide, and N-phenyl-N'-(1 ,3-dimethylhexyl)-p- benzoquinonediimide. A preferred benzoquinonediimide compound comprises N-{4-[(1 ,3- dimethylbutyl)imino]-2,5-cyclohexadien-1-ylidine}, also named [4-(1 ,3-dimethyl- butylimino)-cyclohexa-2,5-dienylidene]-phenyl-amine, and which is available from Flexsys under the product names Q-Flex QDI and 6-QDI. In addition to the quinone diimide, the vinyl functionality polymerization inhibitor also comprises an amount of at least one of a stable free radical compound, such as nitroxyls, or hydroquinone. It has been determined that the use of the at least one of the stable free radical compound or hydroquinone has a synergistic effect on the vinyl polymerization inhibition of quinone diimide. The stable free radical compound comprises nitroxyl compounds. Among the nitroxyl compounds of use with the quinone diimide are selected from the group consisting of 2,2,4,4-tetramethyl-4-hydroxy-1-piperidinyloxy (OH-TEMPO) and 2,2,4,4-tetramethyl-4-oxo-1-piperidinyloxy (OXO-TEMPO). The ratio of quinone diimide to the at least one of the stable free radical compound or hydroquinone can range by weight in a ratio of from about 1 :20 to about 20:1 , preferably, in a ratio of from about 1 :10 to about 10:1 , more preferably in a ratio of from about 1 :3 to about 3:1 , more preferably about 1 :1. Preferably, an effective amount of the vinyl functionality polymerization inhibitor comprising quinone diimide and at least one of the stable free radical compound and/or hydroquinone is added to the composition containing vinyl functionality to retard or inhibit unwanted polymerization of the vinyl groups contained in the composition containing vinyl functionality. The vinyl functionality polymerization inhibitor may be added to the composition containing vinyl functionality in a range by weight of from about 0.5 parts vinyl polymerization inhibitor to about 10,000 parts per million to the composition which contains vinyl functionality. More preferably, the amount of vinyl polymerization inhibitor added to the composition which contains vinyl functionality ranged from about 1 part to about 500 parts per million of the composition which contains vinyl functionality. The vinyl functionality polymerization inhibitor may be added to the compounds containing vinyl functionality directly, as dispersion or as a solution using a suitable liquid carrier or solvent. Any liquid carrier or solvent that is compatible with the composition containing vinyl functionality and the vinyl functionality polymerization inhibitor. The compositions of the present invention prove effective in inhibiting polymerization of compounds containing vinyl functionality as these compounds are subjected to such typical processing steps as distillation and purification. The following examples are meant for illustrative purposes only and are not to be construed as limiting the present invention in any manner whatsoever. Examples All amounts listed in the following examples are by weight, unless otherwise specified. Example 1 Uninhibited acryionitrile (10 ml) was placed in a 50 ml pressure glass tubes fitted with stoppers. The various dosages of the vinyl polymerization inhibitor were added to the uninhibited acryionitrile and the glass tubes were closed and immersed in and oil bath heated at 110°C. Every 30 minutes, the tubes were inspected for turbidity for the presence of polymer. The time when the presence of polymer was observed was noted. OH-TEMPO: 2,2,4,4-tetramethyl-4-hydroxy-1-piperidinyloxy BQDI: Benzamine, N-{4-[(1 ,3-dimethylbutyl)imino]-2,5-cyclohexadien-1- ylidine} The results are found in Tables 1 and 2 hereinbelow. TABLE 1 The results as found in Tables 1 and 2 indicate that benzoquinonediimide (BQDI) was found to have a synergistic effect with stable free radicals and with hydroquinone (HQ) respectively in inhibiting the thermal polymerization of acryionitrile. Example 2 Uninhibited styrene (5 ml) was placed in test tubes and various amounts of the vinyl polymerization inhibitor were added to the various test tubes. The tubes were capped with rubber septums and argon gas was bubbled through the contents of the test tubes at a rate of 10 ml/min for a period of 3 minutes. The tubes were then placed in an oil bath heated to a temperature of 110°C for a period of two hours. OXO-TEMPO: 2,2,4,4-tetramethyl-4-oxo-1 -piperidinyloxy. The amount of polystyrene formed in the test tube was determined using methanol precipitation. The results of this experiment are found in Table 3. TABLE The results as found in Table 3 indicate that OXO-TEMPO: 2,2,4,4- tetramethy!-4-oxo-1-piperidinyloxy and benzoquinonediimide (BQDI) and OH- TEMPO: 2,2,4,4-tetramethyl-4-hydroxy-1-piperidinyloxy were found to be effective in inhibiting the thermal polymerization of styrene and that the combination of BQDI and OXO-TEMPO was found to have a synergistic effect in the inhibition of thermal polymerization of styrene. It is not intended that the examples given here should be construed to limit the invention, but rather, they are submitted to illustrate some of the specific embodiments of the invention. Various modifications and variations of the present invention known to those of ordinary skill in the art can be made without departing from the scope of the invention.

Claims: I claim: 1. A vinyl functionality polymerization inhibitor comprising a quinone diimide compound and at least one of a stable free radical compound and hydroquinone. 2. The vinyl functionality polymerization inhibitor of claim 1 wherein the vinyl functionality polymerization inhibitor comprises a quinone diimide compound and a stable free radical compound. 0 3. The vinyl functionality polymerization inhibitor of claim 2 wherein the stable free radical compound comprises a nitroxyl compound. 4. The vinyl functionality polymerization inhibitor of claim 2 wherein the stable free radical compound comprises 2,2,4,4-tetramethyl-4-hydroxy-1- piperidinyloxy (OH-TEMPO). 5. The vinyl functionality polymerization inhibitor of claim 2 wherein the stable free radical compound comprises 2,2,4,4-tetramethyl-4-oxo-1- 0 piperidinyloxy (OXO-TEMPO). 6. The vinyl functionality polymerization inhibitor of claim 1 wherein the quinone diimide compound comprises a benzoquinonediimide compound. 5 7. The vinyl functionality polymerization inhibitor of claim 6 wherein the benzoquinonediimide compound has the general formula: o wherein R. and R 2 are the same or different and are alkyl, aryl, alkaryl, or aralkyl groups. 8. The vinyl functionality polymerization inhibitor of claim 7 wherein the benzoquinonediimide compound is selected from the group consisting of N,N'- dialkyl-p-benzoquinonediimides and N-phenyl-N'-alkyl-p-benzoquinonediimides. 5 9. The vinyl functionality polymerization inhibitor of claim 7 wherein the benzoquinonediimide compound is selected from the group consisting of N,N'-di- sec-butyl-p-benzoquinonediimide, N-phenyl-N'-methyl-p-benzoquinonediimide, N- phenyl-N'-ethyl-p-benzoquinonediimide, N-phenyl-N'propyl-p- benzoquinonediimide, N-phenyl-N'-n-butyl-p-benzoquinonediimide, N-phenyl-N'- l o isobutyl-p-benzoquinonediimide, N-phenyl-N'-sec-butyl-p-benzoquinonediimide, N-phenyl-N'-tert-butyl-p-benzoquinonediimide, N-phenyl-N'-n-pentyl-p- benzoquinonediimide, N-phenyl-N'-(1 -methylhexyl)-p-benzoquinonediimide, and N-phenyl-N'-(1 ,3-dimethylhexyl)-p-benzoquinonediimide. 15 10. The vinyl functionality polymerization inhibitor of claim 7 wherein the benzoquinonediimide compound comprises N-{4-[(1 ,3-dimethylbutyl)imino]-2,5- cy ohexadien-1 -ylidine}. 11. The vinyl functionality polymerization inhibitor of claim 1 wherein the 2 o ratio of quinone diimide to the at least one of the stable free radical compound and hydroquinone can range by weight in a ratio of from about 1 :20 to about 20:1. 12. The vinyl functionality polymerization inhibitor of claim 11 wherein the ratio of quinone diimide to the at least one of the stable free radical compound 25 and hydroquinone can range by weight in a ratio of from about 1 : 10 to about 10:1. 13. The vinyl functionality polymerization inhibitor of claim 12 wherein the ratio of quinone diimide to the at least one of the stable free radical compound and hydroquinone can range by weight in a ratio of from about 1 :3 to about 3:1. 30 14. The vinyl functionality polymerization inhibitor of claim 13 wherein the ratio of quinone diimide to the at least one of the stable free radical compound and hydroquinone can range by weight in a ratio of from about 1 :3 to about 3:1. 10 15. The vinyl functionality polymerization inhibitor of claim 14 wherein the ratio of quinone diimide to the at least one of the stable free radical compound and hydroquinone can range by weight in a ratio of from about 1 :1. 16. The vinyl functionality polymerization inhibitor of claim 13 wherein the quinone diimide comprises N-{4-[(1 ,3-dimethylbutyl)imino]-2,5-cyclohexadien- 1-ylidine}. 17. The vinyl functionality polymerization inhibitor of claim 16 wherein the stable free radical compound comprises 2,2,4,4-tetramethyl-4-hydroxy-1- piperidinyloxy (OH-TEMPO). 18. The vinyl functionality polymerization inhibitor of claim 16 wherein the stable free radical compound comprises 2,2,4,4-tetramethyl-4-oxo-1- piperidinyloxy (OXO-TEMPO). 19. The vinyl functionality polymerization inhibitor of claim 13 wherein the vinyl functional polymerization inhibitor comprises benzoquinonediimide and hydroquinone. 20. The vinyl functionality polymerization inhibitor of claim 13 wherein the vinyl functional polymerization inhibitor comprises benzoquinonediimide and 2,2,4,4-tetramethyl-4-hydroxy-1 -piperidinyloxy (OH-TEMPO). 21. The vinyl functionality polymerization inhibitor of claim 13 wherein the vinyl functional polymerization inhibitor comprises benzoquinonediimide and 2,2,4,4-tetramethyl-4-oxo-1 -piperidinyloxy (OXO-TEMPO). 22. A method for inhibiting the polymerization of compositions comprising vinyl functionality comprising adding to the compositions comprising vinyl functionality an effective amount of vinyl functionality polymerization inhibitor 11 comprising a quinone diimide compound and at least one of a stable free radical compound and hydroquinone. 23. The method of claim 22 wherein the compositions comprising vinyl functionality comprises vinyl monomers selected from the group consisting of vinyl chloride, vinyl acetate, methylmethacrylate, acryionitrile, methacrylonitrile, acrylic acid, methacrylic acid, styrene, α-methylstyrene and vinyltoluene. 24. The method of claim 22 wherein the vinyl functionality polymerization inhibitor comprises a quinone diimide compound and a stable free radical compound. 25. The method of claim 24 wherein the stable free radical compound comprises a nitroxyl compound. 26. The method of claim 24 wherein the quinone diimide compound comprises a benzoquinonediimide compound. 27. The method of claim 26 wherein the benzoquinonediimide compound has the general formula: wherein R 1 and R 2 are the same or different and are alkyl, aryl, alkaryl, or aralkyl groups. 28. The method of claim 27 wherein the benzoquinonediimide compound is selected from the group consisting of N,N'-di-sec-butyl-p- benzoquinonediimide, N-phenyl-N'-methyl-p-benzoquinonediimide, N-phenyl-N'- ethyl-p-benzoquinonediimide, N-phenyl-N'propyl-p-benzoquinonediimide, N- phenyl-N'-n-butyl-p-benzoquinonediimide, N-phenyl-N'-isobutyl-p- benzoquinonediimide, N-phenyl-N'-sec-butyl-p-benzoquinonediimide, N-phenyl- N'-tert-butyl-p-benzoquinonediimide, N-phenyl-N'-n-pentyl-p- 12 benzoquinonediimide, N-phenyl-N'-(1 -methylhexyl)-p-benzoquinonediimide, and N-phenyl-N'-(1 ,3-dimethylhexyl)-p-benzoquinonediimide. 29. The method of claim 27 wherein the benzoquinonediimide compound comprises N-{4-[(1 ,3-dimethylbutyl)imino]-2,5-cyclohexadien-1-ylidine}. 30. The method of claim 22 wherein the ratio of quinone diimide to the at least one of the stable free radical compound and hydroquinone can range by weight in a ratio of from about 1 :20 to about 20:1. 31. The method of claim 30 wherein the ratio of quinone diimide to the at least one of the stable free radical compound and hydroquinone can range by weight in a ratio of from about 1 :10 to about 10:1. 32. The method of claim 31 wherein the ratio of quinone diimide to the at least one of the stable free radical compound and hydroquinone can range by weight in a ratio of from about 1 :3 to about 3:1. 33. The method of claim 32 wherein the ratio of quinone diimide to the at least one of the stable free radical compound and hydroquinone can range by weight in a ratio of from about 1 :1. 34. The method of claim 22 wherein the vinyl polymerization inhibitor is added to the composition containing vinyl functionality in a range by weight of from about 0.5 parts vinyl polymerization inhibitor to about 10,000 parts per million to the composition which contains vinyl functionality. 35. The method of claim 34 wherein the vinyl polymerization inhibitor is added to the composition containing vinyl functionality in a range by weight of from about 1 part vinyl polymerization inhibitor to about 500 parts per million of the composition which contains vinyl functionality. 13 36. The method of claim 22 wherein the vinyl polymerization inhibitor is added to the composition containing vinyl functionality as a dispersion. 37. The method of claim 22 wherein the vinyl polymerization inhibitor is added to the composition containing vinyl functionality as a solution. 38. The method of claim 22 wherein the stable free radical compound comprises 2,2,4,4-tetramethyI-4-hydroxy-1 -piperidinyloxy (OH-TEMPO). 0 39. The method of claim 22 wherein the stable free radical compound comprises 2,2,4,4-tetramethyI-4-oxo-1 -piperidinyloxy (OXO-TEMPO). 40. The method of claim 22 wherein the vinyl functional polymerization inhibitor comprises benzoquinonediimide and hydroquinone. 5 41. The method of claim 22 wherein the vinyl functional polymerization inhibitor comprises benzoquinonediimide and 2,2,4,4-tetramethyl-4-hydroxy-1- piperidinyloxy (OH-TEMPO). 0 42. The method of claim 22 wherein the vinyl functional polymerization inhibitor comprises benzoquinonediimide and 2,2,4,4-tetramethyl-4-oxo-1- piperidinyloxy (OXO-TEMPO). 43. A composition comprising a composition comprising vinyl 5 functionality and an effective amount of vinyl functionality polymerization inhibitor comprising a quinone diimide compound and at least one of a stable free radical compound and hydroquinone. 44. The composition of claim 43 wherein the composition comprising o vinyl functionality comprises vinyl monomers selected from the group consisting of vinyl chloride, vinyl acetate, methylmethacrylate, acryionitrile, methacrylonitrile, acrylic acid, methacrylic acid, styrene, α-methylstyrene and vinyltoluene. 14 45. The composition of claim 44 wherein the vinyl functionality polymerization inhibitor comprises a quinone diimide compound and a stable free radical compound. 46. The composition of claim 45 wherein the stable free radical compound comprises a nitroxyl compound. 47. The composition of claim 45 wherein the quinone diimide compound comprises a benzoquinonediimide compound. 0 48. The composition of claim 47 wherein the benzoquinonediimide compound has the general formula: 5 wherein R 1 and R 2 are the same or different and are alkyl, aryl, alkaryl, or aralkyl groups. 49. The composition of claim 48 wherein the benzoquinonediimide o compound is selected from the group consisting of N,N'-di-sec-butyl-p- benzoquinonediimide, N-phenyl-N'-methyl-p-benzoquinonediimide, N-phenyl-N'- ethyl-p-benzoquinonediimide, N-phenyl-N'propyl-p-benzoquinonediimide, N- phenyl-N'-n-butyl-p-benzoquinonediimide, N-phenyl-N'-isobutyl-p- benzoquinonediimide, N-phenyl-N'-sec-butyl-p-benzoquinonediimide, N-phenyl- 5 N'-tert-butyl-p-benzoquinonediimide, N-phenyl-N'-n-pentyl-p- benzoquinonediimide, N-phenyl-N'-(1 -methylhexyl)-p-benzoquinonediimide, and N-phenyl-N'-(1 ,3-dimethylhexyl)-p-benzoquinonediimide. 50. The composition of claim 48 wherein the benzoquinonediimide 0 compound comprises N-{4-[(1 ,3-dimethyIbutyl)imino]-2,5-cyclohexadien-1 -ylidine}. 15 51. The composition of claim 43 wherein the ratio of quinone diimide to the at least one of the stable free radical compound and hydroquinone can range by weight in a ratio of from about 1 :20 to about 20:1. 52. The composition of claim 51 wherein the ratio of quinone diimide to the at least one of the stable free radical compound and hydroquinone can range by weight in a ratio of from about 1 :10 to about 10:1. 53. The composition of claim 52 wherein the ratio of quinone diimide to the at least one of the stable free radical compound and hydroquinone can range by weight in a ratio of from about 1 :3 to about 3:1. 54. The composition of claim 53 wherein the ratio of quinone diimide to the at least one of the stable free radical compound and hydroquinone can range 5 by weight in a ratio of from about 1 :1. 55. The composition of claim 43 wherein the vinyl polymerization inhibitor is in a range by weight of from about 0.5 parts vinyl polymerization inhibitor to about 10,000 parts per million to the composition which contains vinyl 0 functionality. 56. The composition of claim 55 wherein the vinyl polymerization inhibitor is in a range by weight of from about 1 part vinyl polymerization inhibitor to about 500 parts per million of the composition which contains vinyl functionality. 5 57. The composition of claim 43 wherein the vinyl polymerization inhibitor is a dispersion. 58. The composition of claim 43 wherein the vinyl polymerization o inhibitor is a solution. 16 59. The composition of claim 43 wherein the stable free radical compound comprises 2,2,4,4-tetramethyl-4-hydroxy-1 -piperidinyloxy (OH- TEMPO). 60. The composition of claim 43 wherein the stable free radical compound comprises 2,2,4,4-tetramethyl-4-oxo-1 -piperidinyloxy (OXO-TEMPO). 61. The composition of claim 43 wherein the vinyl functional polymerization inhibitor comprises benzoquinonediimide and hydroquinone. 62. The composition of claim 43 wherein the vinyl functional polymerization inhibitor comprises benzoquinonediimide and 2,2,4 ,4-tetramethyl- 4-hydroxy-1 -piperidinyloxy (OH-TEMPO). 63. The composition of claim 43 wherein the vinyl functional polymerization inhibitor comprises benzoquinonediimide and 2,2,4,4-tetramethyl- 4-oxo-1 -piperidinyloxy (OXO-TEMPO). 17

Inventors: ARHANCET GRACE B, ARHANCET, GRACE, B.
Applicants: HERCULES INC, HERCULES INCORPORATED
Application year: 2001
Main classification: C07C7
IPC codes: C07C7, C07C15, C07C251, C07C253, C07C255, C09K15