Chemistry of inorganic compounds – Oxygen or compound thereof – Metal containing
Reexamination Certificate
1999-08-21
2001-05-01
Griffin, Steven P. (Department: 1754)
Chemistry of inorganic compounds
Oxygen or compound thereof
Metal containing
C516S093000, C516S100000, C516S112000
Reexamination Certificate
active
06224846
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to boehmite aluminas, more particularly to modified boehmite aluminas that are dispersible in polar organic and/or aqueous media.
2. Description of the Prior Art
Thickened or viscous compositions containing aqueous solutions and/or polar organic liquids have utility in a wide variety of applications. For example, such thickened compositions can be used as coating removers to remove paint, varnish, and similar coatings from surfaces; graffiti removers; deicers for use on aircraft; etc. Typically, the thickened organic-liquid-containing compositions necessarily contain, in addition to water, the desired water miscible (soluble) organic liquid and a thickening additive that imparts the desired rheological properties to the composition. One thickener that has been widely used for water/polar organic solvents is boehmite alumina. Depending on how it is treated, boehmite alumina is dispersible in water and aqueous solutions containing polar, miscible organic liquids. However, boehmite alumina is generally not dispersible in anhydrous mixtures or solutions of polar organic liquids.
There are instances when it would be desirable to prepare a thickened or viscous polar organic liquid that did not contain water. For example, in the deicing of aircraft, the glycols that are used drain to sumps from which the spent glycol can be recovered and reclaimed so as to be reusable. Obviously, the presence of large amounts of water in the glycols increases the costs of reclaiming the glycol. Additionally, there are instances in which the presence of water may lessen the effectiveness of the polar organic liquid, e.g., in certain cleaning applications. Clearly, it would be desirable to have a boehmite alumina that is dispersible not only in water, but also in polar organic liquids essentially free of water.
SUMMARY OF THE INVENTION
It is therefor an object of the present invention to provide a method for modifying a boehmite alumina.
Another object of the present invention is to provide a method for modifying a boehmite alumina to render it dispersible in aqueous solutions, as well as anhydrous, polar organic liquids.
Still a further object of the present invention is to provide a thickened liquid-containing composition wherein the liquid can comprise an aqueous solution or a polar organic liquid.
Still a further object of the present invention is to provide a solid, modified boehmite alumina that can be used in a variety of applications, including thickening aqueous solutions and anhydrous, polar organic liquids.
The above and other objects of the present invention will become apparent from the description given herein and the appended claims.
According to one aspect of the present invention, there is provided a process for making a modified boehmite alumina wherein an aqueous slurry of a boehmite alumina is reacted at a temperature of from 90 to 300° C. with a compound having the formula:
X
(SO
3
M
)n
wherein X is an organic moiety, M is a monovalent cation, and n is an integer reflecting the number of—SO
3
M groups bonded to the organic moiety. The reaction mixture that results contains a boehmite alumina that has been modified, a solid, modified boehmite alumina is thus recovered from the reaction mixture.
In a further aspect of the present invention, there is provided a solid, modified boehmite alumina produced according to the process described above.
In yet another embodiment of the present invention, there is provided a thickened composition comprising a carrier that is liquid at ambient temperature and from about 2 to about 30% by weight of the modified boehmite alumina produced by the process described above.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
According to the process of the present invention, an aqueous slurry or other aqueous dispersion or mixture of a boehmite alumina is reacted at an elevated temperature with a sulfonic acid compound having the formula:
X
(SO
3
M
)
n
wherein X is an organic moiety, M is a monovalent cation, and n is an integer reflecting the number of —SO
3
M groups bonded to the organic moiety. Generally, the reaction is carried out at a temperature of from 90 to 300° C., more preferably from 150 to 250° C. Reaction pressures can vary from atmospheric to super-atmospheric while reaction times can range from as short as 0.1 hour to 30 hours or longer. It will be appreciated that the greatest variable with respect to reaction times is the type of sulfonic acid compound used to modify the boehmite alumina.
The reaction between the boehmite alumina and the sulfonic acid modifier produces a reaction mixture containing modified boehmite alumina, which, depending on the nature of the sulfonic acid compound used, can be in the form of a sol—i.e., basically a colloidal suspension—or in a two-phase mixture wherein the modified alumina is not dispersed in the reaction mixture. In any event, the modified alumina is recovered from the reaction mixture in solid form, the nature of which will vary depending upon the form of the modified alumina in the reaction mixture. For example, in the case where the reaction mixture is a sol, the solid, modified boehmite alumina can be recovered by spray drying or some similar technique that readily produces a powder. Alternatively, if the modified boehmite alumina is not dispersed, e.g., is settled out, the solid modified boehmite alumina can be recovered by decantation, filtering, etc., and the recovered solid dried in cake form, which, if desired or necessary, can be ground to a powder of the desired particle size. In drying the modified boehmite alumina, excessively high temperatures should be avoided, and generally the solid, modified alumina can be dried at a temperature of from about 50° C. to about 250° C., depending upon the sulfonic acid modifier originally used.
To use the modified boehmite alumina in forming thickened compositions, it is generally necessary that the modified boehmite alumina be in powder form and, to this end, grinding can be employed if necessary such that the alumina particles have a particle size generally ranging from about 0.5 &mgr; to about 100 &mgr;. In certain cases, such as, for example, in spray drying, grinding may not be necessary as the particles of the spray-dried material are generally of the appropriate size to form the thickened compositions.
The amount of sulfonic acid modifier employed in the process of the present invention will vary widely, depending upon the nature of the sulfonic acid modifier. Generally speaking, in reacting the boehmite alumina with the sulfonic acid modifier, the mole ratio of alumina calculated as Al
2
O
3
to the mole ratio of sulfonic acid calculated as —SO
3
H will be from about 100:1 to about 1:2. It will be recognized that virtually any modification of the boehmite alumina with the sulfonic acid modifier will increase the polar organic liquid dispersibility of the resulting modified alumina. However, as a practical matter, to achieve ready dispersibility in polar organic liquids or aqueous liquids, the above mole ratios are preferred.
The type of sulfonic acid modifier employed in the process of the present invention can vary widely. Non-limiting examples of suitable sulfonic acid modifiers include alkyl sulfonic acids having the formula:
R
SO
3
M
wherein R is an alkyl group having from 1 to 16 carbon atoms; aryl sulfonic acids having the formula:
Ar
SO
3
M
wherein Ar is an aryl group wherein the aryl group can be a phenyl group, a benzyl group, a tolyl group, a naphthyl group, or any other molecule containing an aromatic nucleus, including condensed six carbon rings such as phenanthrene, anthracene, etc.; metallo-organic compounds with sulfonic acid functionalities; polymers such as sulfonated styrenebutadiene copolymers, sulfonated fluorocarbons, etc.; sulfonated chiral species; and virtually any other sulfonated organic species that can be used to modify the boehmite alumina. Particularly preferred when making a dispersible modified alumina are sulfonic acid modifiers such as
Hurlburt Paul K.
Plummer Daniel T.
Bushman Browning
CONDEA Vista Company
Griffin Steven P.
Ildebrando Christina
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