AU2001295853A1

AU2001295853A1 - A compacted 2,2-dibromo-3-nitrilopropionamide

Info

Publication number: AU2001295853A1
Application number: AU2001295853A
Authority: AU
Inventors: David Feldman; Michael Lupin
Original assignee: Bromine Compounds Ltd
Current assignee: Bromine Compounds Ltd
Priority date: 2000-09-28
Filing date: 2001-09-26
Publication date: 2002-06-20
Anticipated expiration: 2021-09-26

Description

A COMPACTED 2.2-DIBROMO-3-NITRILOPROPIONAMIDE

Field of the invention

The present invention relates to compacted forms of

2,2-Dibromo-3-nitrilopropionamide (DBNPA), namely a granular and/or a

tablet and/or a briquette and/or a pellet form that each has distinguished

commercial and technological advantages over same material in the

known powder form.

Background of the invention

2,2-Dibromo-3-nitrilopropionamide (DBNPA) is a biocide which is used in

industrial water treatment, cooling systems and paper mills. DBNPA is an

efficient biocide with a rapid microbiocidal broad-spectrum activity,

especially in water systems that contain high organic loads.

The main current application of DBNPA is as a liquid formulation, which

contains a mixture of water and an organic solvent such as a glycol, (for

example, polyethylene glycol (PEG), dipropylene glycol (DPG), ethylene

glycol, etc.) and others. The active ingredient (DBNPA) is only 5-25% of such

liquid formulation. The addition of an organic solvent is required for

dissolution of the relatively water-insoluble DBNPA into a liquid

formulation. Prior art teaches the production of DBNPA as a powdered material which

can be used for the preparation of a liquid or solid formulation.

Several types of sustained-release compositions containing DBNPA have

been described:

1) EP 285 209 recites a solid sustained release antimicrobial composition

(in a tablet form), comprising 1 to 90% by wt of a halogenated amide

(including DBNPA) antimicrobial agent, 10 to 80% by wt of a

hydrophilic polymer, 0 to 80% by wt of a compression agent and 0 to

10% by wt of a mold release agent. A composition comprising 40%

DBNPA, 30% Methocel (water soluble cellulose polymer), 27% CaHPO₄

(as compressing agent) and 3% stearic acid, was specifically

demonstrated.

2) WO 98/25458 discloses a solid sustained-release tablet consisting of

DBNPA admixed with a water- soluble natural or synthetic polymer.

Besides the addition of a synthetic polymer into the formulation, the tablet

is coated with an additional water- soluble cellulosic polymer.

3) WO 99/18162 discloses a biocidal powder coating composition comprising

thermoplastic and/or thermosetting resins based on epoxy, polyester,

acrylic or polyurethane resins. The biocide used is a liquid bio-active

material (including DBNPA) and /or specially selected solid bio-active

materials (for example, solid thiazine-thiones, thiolphthalimides, and others). The biocides are homogeneously mixed or bonded with the

particles of the powder.

The process of preparing said biocidal powder coating composition is

characterized by blending the components of the powder coating

composition in a premixer, followed by feeding the mixture into an

extruder, heating to a temperature high enough to melt and mix most of

the major components, and cooling to a solid form.

4) EP 953 284 discloses a composition (in a tablet form) for delivering the

DBNPA biocide to an oil field fracturing fluid, comprising effervescing

agents such as sodium bicarbonate, citric acid and borax. The composition

comprises about 35-65% DBNPA, about 15-28% sodium carbonate, 15-27%

citric acid and up to about 20% borax.

5) EP 954 966 recites controlled release compositions comprising a

biologically active compound, including DBNPA, and a hydroxystyrene

polymer (e.g. hydroxystyrene homopolymer, methylhydroxystyrene

homopolymer, halohydroxystyrene homopolymer and their copolymers).

The weight ratio of DBNPA to the polymer is from 0.1:99.9 to 95:5.

The above prior art is related to sustained-release formulations (including

in a tablet form) which contain various additives, such as polymeric

matrix, binders and compression agents in significant amount. However,

no free DBNPA compound in a compacted form has been used and/or described in the literature. The ability to provide an almost net content of

the active compacted material (such as in a tablet, granule, pellet or

briquette form) is most certainly a significant advantage.

The handling of the existing DBNPA powdered solid material requires

severe safety precautions due to the hazardous nature of this biocide,

especially in a fine powdered form.

An additional problem concerning the application of powdered DBNPA, is

the tendency of the powder to agglomerate, creating lumps and a bulky

material. This phenomenon reduces the flowability of the product and

causes handling and safety problems.

In view of these disadvantages of powdered DBNPA there is a need for a

safer, easy to handle and user-friendly densified p articulate DBNPA. Such

DBNPA should be free of said agglomeration phenomena. As was

mentioned above, the densified forms known in the art have the

considerable drawback of requiring the addition of binders and fillers to

obtain suitable solid forms of the biocide. Therefore, compacted forms known in the art do not provide net or almost net contents of active

material in the tablet, granule, briquette or pellet form. It has now been

found that it is possible to prepare compacted forms of DBNPA which have

sufficient strength and provide a slow release of the active material into

the water without losing their compacted nature. It has further been

surprisingly found that it is possible to prepare compacted forms of this biocide, without employing any binder or filler.

It is an object of the present invention to provide a compacted DBNPA

particle in a granular and/or a tablet and/or a briquette and/or a pellet

form. It is a further object of the present invention to provide a compacted

DBNPA particle having a diameter larger than 0.5 mm., with no binder,

filler or additive added. Yet a further object of the present invention is to

provide a compacted DBNPA particle that contains from 0 to about 3 wt%

of water content. It is yet another object of the present invention to

provide a non-agglomerative DBNPA.

Summary of the invention

The present invention provides an essentially pure compacted

2,2-Dibromo-3-nitrilopropionamide (DBNPA) in a granular and/or tablet

and/or briquette and/or pellet form. A process for producing the same

essentially pure compacted DBNPA is provided, as well.

Description of the preferred embodiments

A major embodiment of the present invention is to provide a process for

obtaining dry-compacted DBNPA in either granular and/or tablet and/or

briquette and/or pellet form. It should be pointed out, however, that as it

is apparent to a person skilled in the art, the actual shape of the

compacted or densified form is not an important parameter, and any

obtainable shape is within the scope of the present invention. The compacted DBNPA particle of the present invention avoids the above

mentioned shortcomings of powdered DBNPA and offers a safer material,

easy to handle, user friendly and at the same time meets the highly

demanding environmental requirements existing for any mode of biocide

application. The compacted DBNPA can be used to prepare a liquid

formulation with various solvents or to generate a fresh aqueous biocide

solution on site.

The application of the compacted DBNPA, according to the present

invention has several advantages:

a) Use of a concentrated solid biocide (>95 wt% active material), and the

avoidance of an organic solvent which is required as a co-solvent to

prepare an aqueous formulation.

b) Simplification of operation and minimization of handling, resulted in

less exposure of the user to the harmful biocide.

c) Increased logistic efficiency and minimization of environmental

pollution.

According to the invention, it has been found that powdered DBNPA (such

as 98 wt% active material) can be compacted in a dry- process, without the addition of a binder, to yield a product in either a tablet and/or a granular

and/or a briquette and/or a pellet form. According to the invention, the process for compacting powdered DBNPA

provides high quality tablets at a moderate pressure of 1300 kg/cm². More

specifically, the process is characterized in that DBNPA is compressed

with a pressure of at least 500 kg/cm², to yield a compacted DBNPA pellet

or tablet. Preferably, the pressure employed is between about 1000 and

2000 kg/cm². Thus, for instance, the density obtained under a compaction

pressure of 1500 kg/cm² (2.1 g/cm³) is 88% of the theoretical density of

DBNPA.

Preferred compacted biocidal products of the present invention, are those

comprising at least 97% (by wt) DBNPA, and between 0 and about 3% (by wt) of water and/or inert ingredient.

The following examples are provided merely to illustrate the invention and

are not intended to limit the scope of the invention in any manner.

Examples

1. Preparation of DBNPA Pellets

Powdered DBNPA was dried and compacted using an hydraulic press,

under three different pressure levels: 500, 1000 and 1500 kg/cm², using a

tungsten carbide cylindrical mold 1.8 cm in diameter. The compaction was

effected using dry powder and a powder which was humidified by the

addition of 2 wt% H₂O. The ratio of the cylindrical pellet height/diameter

is about 1. Each pellet was tested to determine its density and Crushing Strength

(CS). The density of the compact was determined by measuring its

dimensions and weight. CS was measured by standard compression test.

Samples that were humidified by the addition of 2 wt% H₂O were dried at

105°C for 2 hours before the density and CS were measured. The results of

these tests are shown in Table 1. The CS of compacted DBNPA which still

contained 2 wt% H₂O was 28, 44 and 70 kg/cm² for the compaction

pressures of 500, 1000 and 1500 kg/cm² respectively.

Table 1

2. Process for Tableting Powdered DBNPA (Laboratory Scale)

Powder containing at least 98 wt% 2,2-Dibromo-3-nitrilopropionamide

(DBNPA) was weighed into separate portions of about 3 g each, and the

portions were tableted individually in a hydraulic press with a single

action die. The die had a diameter of 18 mm and the pressure applied was 500 psi, equivalent to 1300 kg/cm². The tablets were sealed in individual

polyethylene bags for further measurements.

The tablets were weighed and their thickness measured for calculation of

their density. The crushing strength was determined in the diametral

mode with a Chatillon Digital Force Gauge (DFG-50), with a maximum

force of 25 kg. A total of 40 tablets were measured and the averages of the

determinations are given in Table 2.

Table 2: Physical Properties of the DBNPA Tablets

The static dissolution rate of the DBNPA tablets was determined to be

0.15gr/h + 0.04, by the "weight loss of solid method."

3. Process for Tableting Powdered DBNPA (Scaling-up)

A scale-up of the laboratory tableting process was performed in the

equipment of a tableter manufacturer, in which 200 kg of tablets were

produced from powder containing at least 98 wt% DBNPA. The tableting process was performed using a rotary, multi-die tableter, die

diameter 14 mm, with automatic feeding system. No problems were

observed with filling up to 250-300 tabs/min. Specific compression force :

1500 to 2000 kg/cm².

The DBNPA tablets obtained from the scale-up process were examined and

compared to the ones obtained in the laboratory-scale process (Table 3).

Table 3: Physical Properties of the DBNPA Tablets

The tablets produced during the scale-up process had a smaller diameter

and a greater thickness than those produced at the laboratory- scale, but

the average weight was the same. The density of the tablets from the

scale-up was slightly lower, but the crushing strength was 10% higher.

The static dissolution rate of the DBNPA tablets was determined to be 0.14

+ 0.03 gr/h, by the "weight loss of solid method". This result is very similar

to the dissolution rate that was measured for the tablets that were prepared

in the laboratory (0.15 + 0.04 gr/h). 4. Process for Granulating Powdered DBNPA (Compaction/ granulation)

Production of granular DBNPA by the compaction/granulation process

was performed using a small WP 50 laboratory compactor, with a single 5

mm screen installed in the crushing system. Powder containing at least 98

wt% DBNPA was used. The compaction of the powder to a flake and

subsequent crushing to ~5 mm granules went smoothly, and the material

was screened. 11.5 kg of 2-5 mm granules were produced. The feed rate

was 110 kg/hr. The DBNPA compacted well, without the aid of a binder,

and high quality granules were obtained.

Claims

1. An essentially pure compacted 2,2-Dibromo-3-nitrilopropionamide

(DBNPA) in a granular and/or tablet and/or briquette and or pellet

form.

2. A compacted granular DBNPA, according to claim 1, consisting of

granules having a diameter larger than 0.5 mm.

3. A compacted DBNPA, according to claim 1, comprising 0 to 3 wt%

water.

4. A compacted DBNPA, according to claim 1, comprising 0 to about

5 wt% inert ingredients.

5. A compacted DBNPA, according to claim 1, containing no

additives, such as fillers, binders, and/or plasticizers.

6. A Compacted DBNPA, according to any of claims 1 to 5, for use as

a biocide.

7. A compacted DBNPA, according to any of claims 1 to 6 for use as

an active ingredient in a biocidal composition.

8. A compacted DBNPA, according to claim 1, in a tablet form, for

use as a biocide.

9. A compacted DBNPA, in a tablet form according to claim 8 for use

as an active ingredient in a biocidal composition.

10. A process for producing compacted DBNPA, according to claim 1,

including the step of converting powdered DBNPA into compacted

DBNPA.

11. A process for producing compacted tableted DBNPA, according to

claim 10, including the step of converting powdered DBNPA into

tableted DBNPA.

12. A process for producing compacted granular DBNPA, according to

claim 10, including the step of converting powdered DBNPA into

granular DBNPA.

13. A process for producing compacted tableted DBNPA, according to

claim 10, characterized in that DBNPA is compressed with a

pressure of at least 500 kg/cm², to yield a compacted DBNPA

product.

14. A process according to claim 13, wherein the pressure is between

about 1000 and 2000 kg/cm².

15. Use of an essentially pure compacted

2,2-Dibromo-3-nitrilopropionamide (DBNPA) in a granular and/or

tablet and/or briquette and/or pellet form, in the preparation of a

biocidal composition, substantially as described in the specification.

16. A process for producing an essentially pure compacted DBNPA

from powdered DBNPA, substantially as described and exemplified

in the specification.