WO1998025458A1 - Water soluble coated time release biocide tablets - Google Patents

Water soluble coated time release biocide tablets

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Publication number
WO1998025458A1
WO1998025458A1 PCT/US1997/021697 US9721697W WO9825458A1 WO 1998025458 A1 WO1998025458 A1 WO 1998025458A1 US 9721697 W US9721697 W US 9721697W WO 9825458 A1 WO9825458 A1 WO 9825458A1
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WO
Grant status
Application
Patent type
Prior art keywords
tablets
water soluble
tablet
cellulosic polymer
biocide
Prior art date
Application number
PCT/US1997/021697
Other languages
French (fr)
Inventor
Paul J. Sheskey
Jeffrey M. Marra
Philip J. Brondsema
Original Assignee
The Dow Chemical Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

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Classifications

    • AHUMAN NECESSITIES
    • A01AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01NPRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES, AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
    • A01N25/00Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests
    • A01N25/34Shaped forms, e.g. sheets, not provided for in any other sub-group of this main group
    • AHUMAN NECESSITIES
    • A01AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01NPRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES, AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
    • A01N37/00Biocides, pest repellants or attractants, or plant growth regulators containing organic compounds containing a carbon atom having three bonds to hetero atoms with at the most two bonds to halogen, e.g. carboxylic acids
    • A01N37/34Nitriles

Abstract

The present invention relates to the coating of large size solid time or sustained release tablets containing an active halogenated amide biocide with a water soluble cellulosic polymer, the thus coated tablets and the use of said tablets.

Description

WATER SOLUBLE COATED TIME RELEASE BIOCIDE TABLETS

The present invention relates to the coating of large size solid time release or sustained release tablets containing an active halogenated amide biocide with a water soluble cellulosic polymer. The present invention also relates to the coated tablets and a method for the use of said tablets for biological control in an aqueous system by contacting the aqueous system with the coated, solid tablets.

Solid time release (sustained release) biocide products are well known and are used in many home and commercial fields where they are employed in the killing of, inhibition of, or control of the growth of bacteria, yeast, fungi and algae. An important area for the use of such products includes industrial and home aqueous systems such as water based paints, pulp and paper mills, fresh water supply systems, cooling towers, swimming pools and spas. U.S. Patents 4,800,082 and 4,849,415 are directed to biocidal compositions wherein a variety of active agents can be employed In this patent, solid time release or sustained release articles are prepared by admixing the active ingredient with a water-insoluble, organophilic cellulose ether.

U.S. Patent 4,800,082 teaches the preparation of solid, non-medicinal, antimicrobial sustained release tablets. The tablets are used in various aqueous systems including cooling towers. These tablets are comprised primarily of a biocide in admixture with a hydrophilic polymer In commercial applications, when such tablets are to be used in these aqueous systems, the tablets are usually made in a size of from one inch up to 3 to 4 inches in diameter One of the problems associated with these large tablets is the amount of chipping and/or breakage thereof which occurs during their storage or a combination thereof during the handling of such tablets Another problem associated with these large size tablets relates to the toxicity of the biocide contained therein to those who are physically handling said tablets during their manufacture, storage and/or during the use of the tablets. An additional source of concern relates to the breathing of any dust formed by abrasive contact between the tablets during storage.

One attempt to overcome the above problems has been to store and market the tablets in water soluble polyvinyl alcohol bags, which are added to certain of the above aqueous systems, wherein as the water-soluble bags dissolve therein, the tablets are released therefrom into the aqueous system. The bags, however, tend to become brittle with time or a combination thereof when they are stored at temperatures below 40°F(8°C). In addition, they easily discolor over time; they are permeable to chemical odors from the tablets; the tablets are not immune to breakage; and partially dissolved bags can cause intermittent plugging of openings in the aqueous systems in which they are used. It would be desirable to find a way to make the tablets less prone to breakage and dusting, to protect the user from physical contact with the biocide therein and to maximize the effectiveness of the biocide in its various uses.

The present invention is directed to coated solid time release or sustained release tablets which contain halogenated amide antimicrobial compounds as the active biocide therein and to the coating of the exterior of such tablets with a water soluble cellulosic polymer, which coating has no effect on the time release or sustained release properties of the tablet.

The invention is more specifically directed to the application of a protective coating of a water soluble cellulosic polymer to the surface of large size solid time release or sustained release biocide tablets containing halogenated amine antimicrobials and especially those tablets containing 2,2-dιbromo-3-nιtrιlopropιonamιde (DBNPA) as the biocide.

The water soluble cellulosic polymer coating on the exterior of the tablets protects the tablets from the action of air, light, and prevents the crumbling of the tablet during conventional handling operations The coated tablets can themselves be safely handled with reduced fear of toxic effects from physical contact with the biocide in the tablets by those handling said tablets.

In addition, the coating on the tablets dissolves away within a short time when the tablets are placed in an aqueous system allowing the tablets to have the same biocidal activity as the uncoated tablets.

The solid tablets of the present invention which are coated with a water soluble cellulosic polymer include tablets such as those disclosed in U.S Patent Numbers 4,800,082 and 4,849,415, incorporated herein by reference thereto. These tablets are formulated using standard tableting procedures and comprise the active halogenated amine biocide in admixture with a water soluble cellulosic polymer and, if desired, compression and mold release agents can also be present

The tablets can be in a variety of shapes such as, for example, cylindrical, oval, square, rectangle or spherical. The size of the tablets will vary over a wide range depending upon the particular application and the particular quantities of ingredients and the only limitation placed on the size of the tablets are the limitations of the production equipment employed It is contemplated that for most applications, tablets will vary in size of from one inch up to 3 to 4 inches (2.5-10.0 cm) in diameter and have a thickness of from 0.25 inch up to 3.0 inches, and weigh between about 0.1 gram (g) to 10 kilograms (kg). A preferred size is between 2.0 to 3.0 inches in diameter and have a thickness of from 1.0 to 2.0 inches. A preferred weight is between about 1 g and 1 kg. The active halogenated amide biocides which can be used in the practice of the present invention include brominated nitrilopropionamides, such as, for example, 2-bromo-3- nitπlopropionamide, 2-bromo-2,3-dιnιtrιlopropιonamιde, 2,2-dιbromo-3-nιtπlopropιonamιde, N- (n-butyl)-2-bromo-3-nιtrιlopropιonamιde; N,N-dιmethyl-2,2-dιbromo-3-nιtrιlopropιonamιde, 2- chloro-2-bromo-3-nιtrιlopropιonamιde, N-(n-propyl)-2-ιodo-2-bromo-3-nιtπlopropιonamιde, N- methyl-N-ethyl-2-fluoro-2-bromo-3-nιtπlopropιonamιde, N-phenyl-2-cyano-2-bromo-3- nitnlopropionamide, N-cyclohexyl-2,2-dιbromo-3-nιtπlopropιonamιde, N-benzyl-2-bromo-3- nitnlopropionamide and N-(2,2-dιbromo-3-nιtπlopropιonoyl)pιperιdιne The halogenated amine biocides are well known and the compounds, their preparation as tablets are set forth in U.S. Patent No 4,800,082.

The water soluble (hydrophilic) cellulosic polymers suitable for use in preparing the preformed tablets of the present invention include natural and synthetic water soluble cellulosic polymers such as methylcellulose, hydroxyethylcellulose, hydropropyl cellulose and hydroxypropyl methylcellulose

In addition to the above listed water soluble cellulosic polymers, other natural and synthetic hydrophilic polymers such as gelatin, maltodextπn, xanthan gum and carrageenan; and synthetic hydrophilic polymers such as carboxymethyl guar, hydroxypropyl guar, carboxymethyl galactomannose, polyvinyl acetate and polyvinylpyrrolidone are also suitable for use in preparing the preformed tablets of the present invention. It is also contemplated that mixtures of the above listed polymers can be so employed and such mixtures are within the scope of the present invention.

The solid tablet compositions of the present invention may also optionally contain mold release agents. The particular mold release agent used is not critical and can be any suitable mold release agent known in the art that is compatible with the other ingredients Examples of suitable mold release agents include acid lubricants such as adipic acid, fumaric acid, magnesium sterate and steaπc acid; polymeric lubricants such as polyfluorocarbon lubricants and polyethylene glycol lubricants; and oils such as encapsulated lubricant oils and encapsulated oil-siloxane polymer mixtures.

The solid tablet compositions of the present invention may optionally contain compression agents The particular compression agent used is not critical and can be any suitable compression agent known in the art that is compatible with the other ingredients Examples of suitable compression agents include dicalcium phosphate, lactose, sodium phosphate and calcium sulfate dihydrate.

The amount of antimicrobial compound in the solid tablet compositions of the present invention is between about 1 and 90 percent by weight of the ultimate formulation; a preferred amount is between about 10 and 50 percent; and a most preferred amount is between about 30 and 50 percent The amount of hydrophilic polymer in the solid composition of the present invention is between about 10 and 60 percent by weight of the ultimate formulation; a preferred amount is between about 20 and 50 percent, and a most preferred amount is between about 20 and 40 percent. The amount of compression agent in the solid compositions of the present invention is between about 0 and 80 percent by weight of the ultimate formulation; a preferred amount is between about 5 and 80 percent; and a most preferred amount is between about 20 and 40 percent The amount of mold release agent in the solid compositions of the present invention is between about 0 and 10 percent by weight of the ultimate formulation; a preferred amount is between about 0 and 5 percent; and a most preferred amount is between about 0 and

4 percent.

The preferred antimicrobial compound of the solid composition is 2,2-dιbromo-3- -nitπlopropionamide. The preferred hydrophilic polymer is hydroxypropyl methylcellulose Preferred compression agents are lactose and dicalcium phosphate dihydrate. A preferred mold release agent is steanc acid.

The solid compositions of the present invention are typically formulated using standard tableting procedures known in the art, for example, by either wet or dry granulation; therefore, a compression agent and a mold release agent are particularly valuable in such tablet formation procedures. Suitable tablet formation procedures for forming the solid composition of the present invention can be found, for example, in Johnson, "Tablet Manufacture," Chemical

Technology Review No. 30. The tablets typically have an ultimate compression density ranging from 0.75 g/cubic centimeter (cm)3 to 1.7 g/cm3.

The water soluble (hydrophilic) cellulosic polymers suitable for use in preparing the preformed tablets of the present invention include natural and synthetic water soluble cellulosic polymers such as methylcellulose, hydroxyethylcellulose, hydropropylcellulose and hydroxypropyl methylcellulose.

The water soluble cellulosic polymer coated solid tablets of the present invention are prepared by coating the preformed tablets with the water soluble hydroxycellulose polymer. The water soluble cellulosic polymers suitable for use in coating the preformed tablets of the present invention include polymers such as methylcellulose, hydroxyethylcellulose, hydropropylcellulose and hydroxypropyl methylcellulose. The coating material can be in the form of a solution of the polymer in water or an organic solvent such as methylene chloride, methanol, ethanol, isopropanol or any mixtures thereof The solution can also contain plasticizers, pigments and surfactants and an aqueous solution of a water-soluble cellulosic polymer such as a hydroxycellulose polymer The coating can be applied to the tablets using any of the conventional coating procedures such as, for example, dipping or spraying. The coating is applied in an amount sufficient to provide a polymer film layer thickness (coating thickness) to the tablet of from 1 0.025 millimeter (mm) to 5.0 mm.

Suitable hydrophilic cellulosic polymers are available from The Dow Chemical Company and are known by the trademark Methocel. The following commercially available methylcellulose polymers are suitable for use in the solid composition of the present inventions: Methocel A15LV, Methocel A4C, Methocel A15C and Methocel A4M. The following commercially available hydroxypropyl methylcellulose polymers are suitable for use in the present invention. Methocel K 35LV, Methocel K 100 LV, Methocel K 4M, Methocel K 15M, Methocel E5, Methocel E 15LV, Methocel E50, Methocel E4M, Methocel F50, and Methocel

F4M. The water soluble cellulosic polymer coating solutions for use in the practice of the present invention and procedures for preparing said solutions are well known and are taught in U.S. Patents 4,543,370 and 4,816,298 which are incorporated herein by reference thereto

The invention is further illustrated by the following examples

EXAMPLE I

Coated sustained release tablets were prepared as follows

Twelve tablets having a diameter of 2 7/8 inches (mm) and composed of 80 g of 2,2- dιbromo-3-nιtrιlopropιonamιde (DBNPA) and 80 g of hydroxypropyl methylcellulose (Methocel K-15M) and 40 g of lactose were dipped into an aqueous solution comprising 12 weight percent by volume of METHOCEL E6 The treated tablets were initially dried with a hand held drier and then placed in a drying oven maintained at 45°C. to complete the drying

EXAMPLE II

Coated sustained release tablets were prepared as follows-

Twelve tablets having a diameter of 2 7/8 inches (mm) and composed of 80 g of 2,2- dιbromo-3-nιtrιlopropιonamιde (DBNPA) and 80 g of hydroxypropyl methylcellulose (Methocel

K-15M) were dipped into an aqueous solution comprising 12.0 weight percent by volume of METHOCEL E6 and 1.0 weight percent by volume of green food coloring. The treated tablets were initially dried with a hand held drier and then placed in a drying oven maintained at 45CC. to complete the drying. EXAMPLE III

A test was conducted to determine the effectiveness of the coating on sustained release tablets to resist abrasion when tablets are stored together. The test was conducted as follows:

A group of twelve uncoated tablets of the same type as the ones coated in Example I were weighed and placed in a 5.0 gallon plastic bucket. A group of twelve coated tablets prepared as in Example I were weighed and placed in an identical plastic bucket. The buckets were each shaken on a mechanical reciprocating shaker set at the low speedsetting (no actual speed is given on the shaker) for 1 hour. At the end of this time the tablets were weighed. The average weight of each tablet group before and after shaking and the average weight loss of each tablet group is set forth below in Table I.

TABLE I

Figure imgf000008_0001

EXAMPLE IV

A study was conducted to determine whether a water soluble cellulosic polymer coating on the exterior of large size sustained release tablets would affect the dissolution rate of said tablets when the tablets are placed in an aqueous environment in contrast to uncoated tablets. The study was conducted as follows:

An uncoated tablet of the same type as the ones which were coated in Example II and a coated tablet of the same type as the ones prepared in Example II wherein the coating also contained green food coloring, were placed in a 2.0 gallon pail with water flowing over the tablets for a period of three weeks. It was observed that the green coloring was gone from the coated tablet within the first 24 hours. The two tablets disintegrated at the same rate over the three week period thus showing that the coating did not affect the dissolution rate of the tablets.

Claims

1. A solid sustained release tablet consisting essentially of an active halogenated amide biocide admixed with a water soluble natural or synthetic polymer, said tablet being of a size of from one inch to 4 inches in diameter and said tablet being coated on the outside thereof with a water soluble cellulosic polymer.
2. The tablet of Claim 1 wherein said halogenated amide is 2,2-dιbromo-3- nitπlopropionamide.
3. The tablet of Claim 1 wherein said water soluble cellulosic polymer is hydroxypropyl methylcellulose.
4. A method of preparing coated solid sustained release tablets consisting essentially of an active halogenated amide biocide admixed with a water soluble natural or synthetic polymer and being of a size of from one inch to 4 inches in diameter which comprises coating said tablet on the outside thereof with a water soluble cellulosic polymer.
5. The method of Claim 4 wherein said halogenated amide is 2,2-dιbromo-3- nitπlopropionamide.
6. The method of Claim 4 wherein said water soluble cellulosic polymer is hydroxypropyl methylcellulose.
7 A method for biological control in an aqueous system comprising contacting said system with a biocidal effective amount of coated solid sustained release tablets consisting essentially of an active halogenated amide biocide admixed with a water soluble natural or synthetic polymer and being of a size of from one inch to 4 inches in diameter and said tablets having been coated on the exterior thereof with a water soluble cellulosic polymer.
8. The method of Claim 7 wherein said halogenated amide is 2,2-dιbromo-3-nιtrιlopropιonamιde.
9. The method of Claim 7 wherein said water soluble cellulosic polymer is hydroxypropyl methylcellulose.
PCT/US1997/021697 1996-12-11 1997-11-20 Water soluble coated time release biocide tablets WO1998025458A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US76349996 true 1996-12-11 1996-12-11
US08/763,499 1996-12-11

Applications Claiming Priority (1)

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AU5364398A AU5364398A (en) 1996-12-11 1997-11-20 Water soluble coated time release biocide tablets

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002026699A1 (en) * 2000-09-28 2002-04-04 Bromine Compounds Ltd. A compacted 2,2-dibromo-3-nitrilopropionamide
US8628788B2 (en) 2006-02-24 2014-01-14 Bromine Compounds, Ltd. Formulations containing a non-oxidative biocide and a source of active halogen and use thereof in water treatment

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4800082A (en) * 1987-03-23 1989-01-24 The Dow Chemical Company Sustained release microbiological control composition
US4816298A (en) * 1987-11-27 1989-03-28 The Dow Chemical Company Method of making a granular, cold water dispersible coating composition

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4800082A (en) * 1987-03-23 1989-01-24 The Dow Chemical Company Sustained release microbiological control composition
US4816298A (en) * 1987-11-27 1989-03-28 The Dow Chemical Company Method of making a granular, cold water dispersible coating composition

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002026699A1 (en) * 2000-09-28 2002-04-04 Bromine Compounds Ltd. A compacted 2,2-dibromo-3-nitrilopropionamide
JP2004509943A (en) * 2000-09-28 2004-04-02 ブローミン コンパウンズ リミテッド Compression 2,2-dibromo-3-nitrilopropionamide
US7524884B2 (en) 2000-09-28 2009-04-28 Bromine Compounds Limited Compacted 2,2-dibromo-3-nitrilopropionamide
US8114905B2 (en) 2000-09-28 2012-02-14 Bromine Compounds Limited Compacted 2,2-dibromo-3-nitrilopropionamide
US8628788B2 (en) 2006-02-24 2014-01-14 Bromine Compounds, Ltd. Formulations containing a non-oxidative biocide and a source of active halogen and use thereof in water treatment

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