Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2000-01-18
2002-12-17
McKane, Joseph K. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C424S405000, C424S723000, C424S464000, C514S388000, C510S192000, C510S382000, C510S381000
Reexamination Certificate
active
06495698
ABSTRACT:
TECHNICAL FIELD
This invention relates to the compacting of 1,3-dihalo-5,5-dimethylhydantoins other than 1,3-dibromo-5,5-dimethylhydantoin without use of binders, and to the novel compacted forms so produced, which, by virtue of their characteristics and physical properties, are superlative biocidal water-treating 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. Thus typically they are supplied in solid forms such as granules, tablets, or briquettes, and delivered into the water being treated by means of water flow through an erosion feeder.
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 20 November 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-propyl-hydantoin as a binder in making compacted forms of halogenated hydantoins.
U.S. Pat. No. 4,745,189 describes formation of halogenated dimethylhydantoinby 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.
U.S. Pat. No. 4,560,766 teaches that halogenated dimethylhydantoinper 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.
It would be of great advantage to provide particulate 1,3-dihalo-5,5-dimethylhydantoins useful for making granules, 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.
SUMMARY OF THE INVENTION
This invention involves the discovery, inter alia, that 1,3-dihalo-5,5-dimethylhydantoins other than 1,3-dibromo-5,5-dimethylhydantoin can be compacted without need of a binder of any kind.
Accordingly, this invention provides, inter alia, novel, binder-free, pressure compacted articles of 1,3-dihalo-5,5-dimethylhydantoins other than 1,3-dibromo-5,5-dimethylhydantoin, and methods of producing such compacted articles from such binder-free 1,3-dihalo-5,5-dimethylhydantoins.
The 1,3-dihalo-5,5-dimethylhydantoins other than 1,3-dibromo-5,5-dimethylhydantoin are 1,3-dichloro-5,5-dimethylhydantoin, 1-bromo-3-chloro-5,5-dimethylhydantoin, and 1-chloro-3-bromo-5,5-dimethylhydantoin, and mixtures thereof. For ease of reference, such compounds (excluding 1,3-dibromo-5,5-dimethylhydantoin) are sometimes referred to hereinafter as “halogenated hydantoins”. Even though devoid of a binder, pressure compacted articles formed from particulate halogenated hydantoins have remarkable crush strength. In contrast, so far as is known, all previously known particulate forms of virgin 1,3-dibromo-5,5-dimethylhydantoin cannot be pressure compacted into tablets When attempts were made to form such tablets, it was found that when released from a tableting die, the compacted shape would “delaminate”, meaning that the compacted agglomerate would break apart into smaller pieces.
Moreover, when compacted without a binder, granules, tablets, briquettes, or other relatively small shapes formed from the halogenated hydantoins have excellent physical properties for use in water-treatment systems. The shapes erode at slow, but essentially constant, rates when maintained in a constant flow of water. They withstand the customary physical stresses encountered in packaging, conveying, handling, shipping, storage, and use. The compacted solid forms of this invention produced directly from the 1,3-dihalo-5,5-dimethylhydantoins other than 1,3-dibromo-5,5-dimethylhydantoin have excellent crush strength even when formed without a binder.
While many ways of producing halogenated hydantoins are known, the best way of producing them involves process technology fully described in commonly-owned copending application Ser. No. 09/484,844, referred to above.
In converting the halogenated hydantoins into granules, conventional processing equipment can be used under the usual operating conditions. Typically, the finely divided halogenated hydantoin is compressed into sheet form by means of a roll compactor. This sheet in turn is broken up into small granules by a mechanical device, such as a Chilsonator® breaker (The Fitzpatrick Company, Elmhurst, Ill.). The granules are then classified by screening into the desired size range. Undersized granules are typically recycled to the roll compactor, whereas oversized granules are recycled to the breaker device.
The formation of tablets and other compressed shapes such as briquettes from the halogenated hydantoins can also utilize known processing equipment and, for the most part, known procedures. However, in conducting compaction of the virgin halogenated hydantoins particulate solids in the absence of a binder, it is important that the compaction pressure be sufficient to induce plastic deformation and interparticulate binding of the particles. At the same time, the compaction pressure should not be so great as to produce a compacted product which delaminates on expulsion from the die. Typically, suitable compaction pressures in the practice of this invention
Albemarle Corporation
McKane Joseph K.
Spielman, Jr. Edgar E.
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