Compositions – Water-softening or purifying or scale-inhibiting agents – Plant or organic material containing
Reexamination Certificate
2000-01-18
2003-01-21
Lovering, Richard D. (Department: 1712)
Compositions
Water-softening or purifying or scale-inhibiting agents
Plant or organic material containing
C252S187200, C264S211110, C510S191000, C514S389000, C514S398000, C514S951000, C548S317100
Reexamination Certificate
active
06508954
ABSTRACT:
TECHNICAL FIELD
This invention relates to novel forms of 1,3-dibromo-5,5-dimethylhydantoin which, by virtue of their characteristics and physical properties, are superlative biocidal water-treating agents and brominating agents.
GLOSSARY
As used herein the terms “halogen”, “halogenated”, and “halo” are with reference to bromine or chlorine, or both.
BACKGROUND
1,3-Dihalo-5,5-dialkylhydantoins, especially 1,3-dibromo-5,5-dimethylhydantoin, 1,3-dichloro-5,5-dimethylhydantoin, 1-bromo-3-chloro-5,5-dimethylhydantoin, and 1-chloro-3-bromo-5,5-dimethylhydantoin, or mixtures of two or more of them, are biocidal agents for use in water treatment. These compounds are, in general, sparingly soluble in water. Each of these compounds except 1,3-dibromo-5,5-dimethylhydantoin, has been supplied in compacted solid forms such as granules, tablets, or briquettes, and delivered into the water being treated by means of water flow through an erosion feeder. The compacted forms of the 1,3-dichloro-5,5-dimethylhydantoin have been produced using a binder. Of the three manufacturers of compacted forms of N,N′-bromochloro-5,5-dimethylhydantoin, two such manufacturers are known to utilize a binder in producing the compacted forms. The technology used by the other manufacturer to produce such compacted forms has not been disclosed. So far as is known, never before has 1,3-dibromo-5,5-dimethylhydantoin powder been converted into a compacted form by any method.
Over the years considerable effort has been devoted to the search for improved methods for producing such compounds. In U.S. Pat. No. 2,971,960 N-brominated compounds such as N-brominated 5,5-di-lower-alkyl hydantoins are formed by treating the alkylhydantoin with bromine in an acidic aqueous solution containing hypochlorite, preferably at a pH between 1 and 4. However, the method of choice has been halogenation of the alkylhydantoin in a basic aqueous medium. Almost invariably the halogen has been introduced into, or formed in situ in, the aqueous medium containing the alkylhydantoin. See in this connection U.S. Pat. Nos. 2,398,598; 2,779,764; 2,868,787; 2,920,997; 2,971,959; 3,121,715; 3,147,259; 4,532,330; 4,560,766; 4,654,424; 4,677,130; 4,745,189; PCT
Publication No. WO 97/43264, published Nov. 20, 1997; Orazi and Meseri,
Anales Assoc. Quim. Argentina,
1949, 37, 192-196; Orazi and Meseri,
Anales Assoc. Quim. Argentina,
1950, 38, 5-11; Corral and Orazi,
J. Org. Chem.,
1963, 23, 1100-1104; Jolles,
Bromine and its Compounds,
Ernest Benn, London, 1966, p. 365; and Markish and Arrad,
Ind. Eng. Chem. Res.,
1995, 34, 2125-2127.
The N,N′-dihalogenated dialkylhydantoin products formed by such processes are formed as powdery solids. For use in many applications the dry powders need to be converted into larger forms such as granules, tablets, or briquettes. This in turn has presented problems associated with providing densified or compacted products with sufficient strength to withstand the physical stresses encountered in packaging, conveying, handling, shipping, storage, and use. The nature of these problems have been described, for example, in U.S. Pat Nos. 4,532,330; 4,560,766; 4,654,424; 4,677,130; 4,745, 189; and 5,565,576. The approaches described in these patents for alleviating one or more such problems involve use of additional or other materials. Thus in U.S. Pat. Nos. 4,532,330 and 4,621,096, halogenated dimethylhydantoins are mixed with calcium chloride and water, and the mixture is compacted by compression into the desired shape. In U.S. Pat. Nos. 4,560,766 and 4,654,424, halogenated ethylhydantoins are used instead of halogenated dimethylhydantoins and are compacted as such, or are melt blended with halogenated dimethylhydantoins. U.S. Pat. No. 4,677,130 describes forming dry blends of the halogenated dimethylhydantoin with particulate alkali metal or alkaline earth metal salt followed by compression to form a compacted product such as a tablet. PCT Publication No. WO 97/43264 describes the use of 1,3-bromochloro-5-methyl-5-propylhydantoin as a binder in making compacted forms of halogenated hydantoins.
U.S. Pat. No. 4,745,189 describes formation of halogenated dimethylhydantoin by halogenating the hydantoin in an aqueous mixture under alkaline conditions in the presence of a halogenated alicyclic organic compound such as dichloromethane. The Examples of the patent describe the formation of N,N′-bromochloro-5,5-dimethylhydantoin products comprised of large particles. However, so far as is known, no 1,3-dibromo-5,5-dimethyl-hydantoin having an average particle size of at least 175 microns has been described anywhere in the prior art.
U.S. Pat. No. 4,560,766 teaches that halogenated dimethylhydantoin per se cannot be used for making low-dust powders, granules, tablets, flakes, compacted forms, cast forms, and carrier-coated products without the aid of a binder.
Despite extensive research efforts in the field, a number of additional serious problems remain unsolved. For one thing, processes utilized in the production of 1,3-dihalo-5,5-dimethylhydantoins form powders which have the undesirable characteristic of producing large quantities of irritating, corrosive dusts when handled and used. Further, products formed from bromine-containing 1,3-dihalo-5,5-dimethylhydantoin, which are widely distributed as consumer products, have aesthetic properties that are less than desirable. Typically, products produced from such bromine-containing 1,3-dihalo-5,5-dimethylhydantoins have a distinct yellow coloration.
Other remaining unsolved problems relating to previously known 1,3-dihalo-5,5-dimethylhydantoins involve their lack of acceptable flowability characteristics. In particular, 1,3-dihalo-5,5-dimethylhydantoin powders exhibit high interparticulate friction and thus cannot be readily discharged from feed hoppers or be transferred without “bridging” or “arching” when passing through conduits or screw conveyors. In such operations, “bridging” or “arching” (which are synonymous terms) is a condition in which the particles stick together without fusing to form lumps or clumps or balls of particulate material, which in turn seriously interfere with or impede further flow of the material. Another problem associated with 1,3-dihalo-5,5-dimethylhydantoin powders is their strong tendency to undergo “ratholing” when being discharged from a conical hopper or feeder. This means that, rather than discharging evenly from the device, the powder discharges from the center only, leaving an annular mass of the powder suspended against the interior sloping conical sides of the device. In severe cases, it becomes necessary to release such suspended powder by striking the exterior of the device with a hammer or baseball bat.
It would be of considerable advantage if 1,3-dibromo-5,5-dimethylhydantoins could be provided as powders having little or no dusting characteristics. It would also be of great advantage to provide particulate 1,3-dibromo-5,5-dimethylhydantoins useful for making granules, caplets, tablets, flakes, compacted forms, cast forms, and carrier-coated products without the aid of a binder, and without use in the production process of any organic halogen compound such as dichloromethane. Moreover, the provision of 1,3-dibromo-5,5-dimethylhydantoins having an average particle size larger than available heretofore would be a most welcome contribution to the art. Still other features of considerable advantage in the art would be the provision of 1,3-dibromo-5,5-dimethylhydantoins having superior flowability characteristics and more appealing aesthetic properties.
SUMMARY OF THE INVENTION
This invention involves the discovery, inter alia, of 1,3-dibromo-5,5-dimethylhydantoin particulate solids having unique physical properties. Such 1,3-dibromo-5,5-dimethylhydantoin particulate solids can be produced by the process described in commonly-owned U.S. application Ser. No. 09/484,844, filed Jan. 18, 2000.
More particularly, this invention provides 1,3-dibromo-5,5-dimethylhydantoin particulate solids having larger average particle sizes than
Elnagar Hassan Y.
Howarth Jonathan N.
Peters Bruce C.
Spielman, Jr. Edgar E.
Thomas Dustin H.
Albemarle Corporation
Lovering Richard D.
Spielman, Jr. Edgar E.
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