FORM-2
THE PATENTS ACT, 1970
COMPLETE SPECIFICATION
SECTION 10

TITLE

PROCESS FOR MANUFACTURING OF NON-SWALLOWABLE ALUMINIUM PHOSPHIDE TABLETS

APPLICANTS

SHROFF RAJNIKANT DEVIDAS MUMBAI, INDIAN INHABITANT 202, PARSHURAM, 40 PALI HILL, BANDRA, MUMBAI - 400 050, STATE OF MAHARASHTRA, INDIA PNDIAN

The following, Specification particularly describes and ascertains the nature of this invention and
the manner in which it is to be performed :- 13.6.02


This invention relates to A process for manufacture of non-swallowable Aluminium Phosphide tablets. These tablets are to be used for generation of Phosphine gas in the godown of pulses, in government warehouses,in small and big godowns, shops, hostels, cnateen and even in houses for the protection of stored foodgrains.
The tablets produced in this invention , have characteristic large size.Iow content of Aluminium phosphide active and the presence of a small quantity of bittering compound making it difficult to swallow.
Aluminium phosphide tablets is one of the most important fumigant to protect foodgrains and other stored agricultural products and comodities from damage by stored product insects and rodents pests.
Aluminium phosphide (AI.P) has molecular weight of 57.96 and commonly known as Aluminium phosphide (IUPAC), CS No. [20859-73-8]. It forms dark grey to yellowish crystals, m.pt.>1000° C. Though stable when dry, it reacts with moist air, violently with acids, producing phosphine and is used to generate the latter toxicant. Phosphine PH3 (Molecular weight 34.00) [CAS No. 7803-51-2] is a gas, with an objectionable ammonici odour; b.pt. -87.4 ° C, flash point - 132.5 ° C. Sparingly soluble in water. It is spontaneously flammable in air ( due to the presence of traces of other hydrides of phosphorus) with an explosion limit of 26.1 - 27.1 g/ cubic m. Phosphine is highly insecticidal and is produced from Aluminium phosphide for fumigation purpose; silos using 1-3 g/MT grain; goods at 0.75 - 1.5 g/ cubic mspackpile. Dosages vary with fumigation conditions. Fumigation takes 3-10 days and should be undertaken only by trained personnel. Adequate airing after this period is checked by a gas detector. The residue is non-poisonous and is removed in the subsequent screening of the grains, comnines violently with oxygen and halogens liberates hydrogen and forms the phosphide when passed over heated metal. Forms phosphoniumsalts when brought in contact with halogen acids.
Aluminium phosphide formulations are normally based on the product containing 570 g/kg; they include: crepe paper bags (34 g powder to produce 11 g phosphine); tablets (3 g, producing 1 g phosphine); pellets (0.6 g, containing 55% aluminium phosphide,40% ammonium carbamate and 5% aluminium oxide). These formulations are inserted by probe into the material to be fumigated, e.g. Grain, the moisture content of which should be > 10%. The pellets evolves a non-flammable mixture of phosphine, ammonia and carbon dioxide.

FIELD OF INVENTION
The present invention relates to a process for manufacture of non-swallowable Aluminium phosphide tablets. More particulariythis invention relates to Aluminium phosphide tablet, a method to prepare non-swallowable Aluminium phosphide tablets, a non-swallowable composition useful to avoid suicidal cases which are presently in news with reference to Aluminium phosphide tablets, and to a method for preparation of non-swallowable tablets. In particular this invention relates to tablet(s) comprising Aluminium phosphide, ammonium carbamate, urea, zinc sterate, molten wax/molten crystalline wax, bittering agent (like denotinium benzoate/denatonium saccharide as such or a mixture thereof); a method to prepare tablet, of Aluminium phosphide, having a tendency of avoiding auto-ignition of phosphine gas generated during the usage of Aluminium phosphide tablets, with delayed release of phosphine, eliminating the chances of accidentalpoisoning by inhalation during handling of accidental/intentional swallowing.with each tablet weigh 5-25 gm preferably 10 -15 gm and more preferably about 12 gm, with more quantities of ammonium carbamte and urea in comparison to the presently available tablets in the market, and with bittering agent, bigger size, ability of releasing phosphine slowly, with a reduced risk to workers, farmers and pest control operators, during the handling, manufacturing and packing of these tablets.
BACKGROUND FOR THE INVENTION
Today, there are large quantities of foodgrains and other agricultural products like pulses stored in government warehouses, in small and big godowns, shops , hostels, hotels, canteens and even in households.
The food grain stored in this manner requires to be protected from damage by insects and rodents which infest the storage areas. The fumigant exclusively used for this purpose is Phosphine, an extremely toxic gas which is generated in the hydrolysable metal the storage areas by the action of moisture (in the atmosphere) on some metal phosphide like Aluminium and Magnesium Phosphides.
In the form in which these metal phosphide is made available to consumers is a tablet in which the metal phosphide is mixed with inert ingredients which serve to lower the rate at which phosphine is generated and also to release inert gases ( which reduce the risk of spontaneous combustion of the phosphine being generated).
These tablets are available in a packing of sealed tin containers containing extruded aluminium metal tubes each containing 10 or 20 tablets of 3 grams each. The workers handling aluminium phosphide (or Magnesium Phosphide)

during the manufacture, tableting and packing as well as workers who use these tablets to fumigate the godowns or storage areas are exposed to risks, inherent, in handling a very highly toxic material.
The three gram tablet with an AIP content of 56 or 57% releases one gram of phosphine.
These tablets contain a certain quantity of Ammonium Carbamate or urea or similar chemicals which decompose while aluminium phosphide is being hydrolyzed to produce phosphine. The quantity ammonia and carbon dioxide which is released by the decomposition of these additives viz. ammonium carbamate, urea etc. effectively inhibits any tendency for auto-ignition of the phosphine produced. This tendency for auto-ignition during phosphine generation was one of the important factors which had prevented the general use of aluminium phosphide until the method of preventing auto ignition in 1952 or 1953 was discovered and disclosed in British patents granted to the German investors. These tablets often were coated with paraffin wax which delayed with release of phosphine from tablet after they were placed in site for the purpose of fumigation.
The new safer tablet disclosed by this invention also is designed to eliminate the chance of accidental poisoning by inhalation during handling or accidental or intentional swallowing beside inhibiting the anti-auto ignition tendency.
Besides being proof against auto ignition, the safer new formulation being described here has three different features which make the tablets being safely handled by the framer or the fumigators and by the general public.
First, the tablet currently in use wighs 3 grams, containing 56 to 60% of aluminium phosphide and its dimensions are 19 mm in diameter and 6 mm in thickness. These tablets can be easily swallowed either accidentally or by design. These tablets release 1 gm. Of phosphine within a few minutes of being swallowed and are not safe when handled by untrained persons.
Today Aluminium Phosphide tablets of 3 gms. containing 56% to 60% active ingredient Aluminium Phosphide is used in government warehouse. It is also used by a professional pest control operators, who can fumigate for private parties who have a problem of infestation in their warehouses. Small warehouses, small farmers and food processing units are not able to take the services of pest control operators. As Aluminium Phosphide is very simple to use, they are tyring to use Aluminium Phosphide tablets available in the grey market. The sale to such parties are not permitted by the Government.
k

In India because of press publicity and social conditions, more and more cases of suicide with Aluminium Phosphide 3 gm tablets are being brought to light. Because of such suicide cases, government has restricted the use and availability of these 3 gms. tablets. As an alternative,. 5 or 10 gms. small pouches dose 2-3 tablets contained in metal cases are available but these are popular in the market because of cost and inconvenience in use.
In the preferred form of this invention, the tablet weighs 12 gms. and contains only 15% of Aluminium Phosphide. The quantities of Ammonium Carbamate / Urea is much higher. The tablet will also contain about 40 to 50 ppm of Denatonium Benzoate known in the market as Bitrin. This is a very bitter substance making the tablet almost impossible to swallow.
To summarise the safety feature of this invention.
(i) On account of size of the tablet and presence of Bitrin, any event of accidental or intentional swallowing is almost impossible.
(ii) The slow release of Phosphine prevents accumulation of the gas. Also the larger proportion of gases like carbon dioxide and ammonia eliminates the risk of auto-ignition.
(iii) The slow release of Phosphine and the dilution of the gas by non-toxic gases like carbon dioxide and ammonia greatly reduce the risk of workers and pest control operators handling the manufacture and packing.
OBJECTS OF THE INVENTION
It is an object of this invention to provide a process for preparing the non-swallowable tablet of Aluminium Phosphide.
It is another object of this invention to provide a process for preparing a non-swallowable tablet of Aluminium Phosphide of size (40 mm dia) larger than the size of Oseophagus.
It is yet still an additional other object of this invention to provide a process for preparing the tablet of Aluminium Phosphide having an emetic agent(s).
It is yet another object of this invention to provide a process for preparing tablet having Aluminium Phosphide, ammonium carbamate, urea, zinc stearate, graphite, calcium carbonate, molten wax/molten crystalline was, and bittering agent.

It is still yet an additional object of this invention to provide a process for preparation of a tablet having a tendency of avoiding auto-ignition of phosphine gas generated during the usage of Aluminium phosphide tablets, with delayed release of phosphine, eliminating the chances of accidental poisoning by inhalation during handling or accidental/intentional swallowing of the tablet for suicide.
It is yet still an additional object of this invention, to provide a process for preparation of a tablet with less amount of Aluminium phosphide content. ^';
The above objects and other objects are met in this invention which is more particularly described herein after without limitation.
DESCRIPTION OF THE PROCESS
A process for the manufacture of non-swallowabie Aluminium phsophide tablets comprising the addition of weighed quantity of the ammonium carbamate, urea into a blender; thereafter Aluminium phosphide is added in the blender; the mixture of the step (b) is blended to have a homogenous mixture; to the mixture of step ( c) Zinc stearate and graphite are added and mixed thoroughly; then wax and bittering agent is added to the mixture, obtained in step (d), and homogeneously mixed; thereafter feeding the mass of step(e) into the hopper of the tablet machine for tableting; then the tablets obtained after step (f) are kept in a pressure vessel; thereafter the pressure vessel of step (g) is heated; then the pressure vessel is cooled to room temperature; thereafter collection of the tablets from pressure vessel of step (i) are done for packing.
This invention will be better understood and the object and advantage will become clear from the following description and the block diagrams given:
BLOCK DIAGRAM 1 : is giving the details of the process. Weighed quantity of Aluminium powder and Phosphorus are added to the reactor 'R' with stirrer as shown in the diagram. With exothermic reaction , Aluminium phosphide approximately 85 % pure is formed as shown in vessel 'V.
The other ingredients like;
1. Ammonium Carbamate and Urea (fire retardant)
2. Zinc stearate and graphite (lubricant)
3. Mixture of molten wax and Bitrin (repellant and binder)
are kept in weighed quantitiesin the holding vessels 1,2 and 3.
Molten Microcrystalline wax - A and Bitrin -B are first mixed in vessel 3 and are added to the blender and vessel 1 and 2 are added later. After one hour of mixing, the material is taken out.

Tableting machine ' T * produces large sized tablet of approximately 35 -45 mm diameter and around 7 - 8 mm thickness weighing between 10 - 20 gms.
These tablets contain wax and bittering compound equally distributed. This is achieved by placing the tablet in a autoclave 'P' and heated to 70-80 Deg C unser pressure. After nearly 30-40 minutes, the vessel is again cooled and tablets are taken out. During this process, the wax is molten and again solidifies. Not only tablets become harder, the wax and the bittering compound in higher concentration comes on the outer surface of the tablets making the tablets much more safer and suicide proof and has the vomiting effect of this compound increases. These tablets are then suitably packed as shown in Sheet 3.
Sheet 4 : gives illustration of how the bittering compound which is equally distributed in the tablet comes out more on the outer surface and less in the inner area of the tablet.
EXAMPLE 1:
18 kilos of Aluminium Phosphide of 83% was taken directly from reactor to the blender. About 42 kilos of Ammonium Carbamate,and 30 kilos of Urea were added. 5 kilos of Zinc Stearate and 5 kilos of Molten wax containing 5 gms of Denatonium Benzoate were added to the blender.
After blending for 45 minutes, the material was taken out for tableting. These tablets were put in a pressure vessel and kept hot for 30 minutes at 80 Deg C. After the vessel was cooled, the tablets 42 mm diameter and 8 mm thickness were collected , each weighing 12 gms.They were suitably packed. These tablets had a shiny surface due to the higher concentration of the wax. Tablet was analysed and it contained 15 % of Aluminium Phosphide.
EXAMPLE 2 :
27 kilos of Aluminium Phosphide of 84% was taken from the container.
Approximate quantities of Ammonium Carbamate, Urea, Zinc Stearate were
added. When blender was working , molten wax contain nearly 200 ppm Bitrin
(Denatonium Benzoate) were added and blender was blended for approximately 60
minutes.
The mixture from the blender was taken to the tableting machine where tablets of 42 mm were taken out for further treatment.
These tablets were put in a pressure vessel and kept hot for 30 minutes at 70 Deg C. The tablets which were shining due to higher concentration of wax on the outer surface, 12 gm tablet contained 15.4 % of Aluminium Phosphide.

We Claim
1. A process for the manufacture of non-swallowable Aluminium Phosphide tablets comprising the
following steps:
a. adding 5% wax containing bittering agent 50-100 ppm, by weight of the composition, in
a blender;
b. mixing 42% of ammonium carbamate and 30% of urea, by weight of the composition,
and adding to the wax of step (a) in the blender;
c. adding a mixture of 5% zinc stearate and 5% graphite, by weight of the composition, to
the mixture in the blender;
d. blending the mixture of step (c) to have a homogeneous mass;
e. thereafter adding 18% of Aluminium phosphide (purity 83-85%), by weight of the/'
composition, in the blender;
f. blending the mixture of step (e) for one hour to form a homogeneous mass;
g. feeding the homogeneous mass of step (f) into the hopper of the tablet machine for
preparing tablets of 35-45 mm diameter, 7-8 mm thickness and 10-20 gm weight;
h. thereafter surface finishing the tablets obtained in step (g) by heating the tablets in a
pressure vessel at a temperature of 70-80°C for 30-40 minutes; i. cooling the pressure vessel of step (h) to room temperature (20-35°C); j. collecting the tablets from the pressure vessel of step (i) for packing;
2. A process as claimed in claim (1), wherein the active content of aluminium phosphide in the tablet is preferably in the range of 15.1 - 15.4% (all in % by mass).
3. A process as claimed in claim (1), wherein the diameter of the tablet is preferably 40 - 42 mm.
4. A process as claimed in claim (1), wherein the weight of the tablet preferably ranges from 11.5 -12.5 gm.
5. A process for manufacture of non-swallowable Aluminium Phosphide tablets substantially as herein described in the text, in the examples and in the attached drawings.



(SHROFF RAJNIKANTXPEVIDAS)
Dated 08* day of May 2001
To
The Controller of Patents
The Patent Office at Mumbai