FIELD OF THE INVENTION:
The present invention relates to the field of agrochemicals. In particular, the present invention pertains to cylindrical pellets of Sulphur and a process for preparing the pellets.
BACKGROUND OF THE INVENTION:
Sulphur is one of the 17 essential plant nutrients. It is essential for the growth and development of all crops, without exception. Sulphur performs some key functions in plants such as formation of chlorophyll that permits photosynthesis, protein production, synthesis of oils, activation of enzymes, and is associated with special metabolisms in plant and the structural characteristics of protoplasm. Use of sulphur results in improvement in both yield and quality of the crop.
Sulphur is widely employed as a fertilizer or soil nutrient, especially in alkaline soils to increase soil water intake and aeration, improve the physical condition of the soil, eliminate harmful alkalinity and sodium problems and increase the availability to the plant of elements in the soil necessary for plant life.
Sulphur is most suitably employed in elemental form and different processes have been proposed for providing sulphur in a form for use as a fertilizer. One of the problems in the prior art with the use of particulate sulphur in fertilizer applications is that when applied in the form of large particles greater than 100 micron size, elemental sulphur is very slow in reaching the needy roots of plants to pass on the required nutrients. However, with smaller sized particulate sulphur, at a particle size between 20-85 microns, absorption and conversion of particulate sulphur is optimal and much more effective. Nonetheless, very small particles resulting in clouds of dust which is unpleasant for workers and end users and may be hazardous to health; under certain circumstances there is also a danger of explosion.
Canadian Patent No. 1,054,821, describes a method of producing granular sulphur-bentonite mixture. However, the granules are of irregular shape and thus have a greater volume when packed for transport increasing packing and transportation costs. Furthermore, these granules are friable and during the process and transportation result in fine particles or dust, which is not desirable.
U.S. Pat. No. 4,133,669, described a method of producing a water-degradable solid pellet of bentonite and elemental sulphur. However, the process is costly and results in spheroid particles which still results in increased packing and transportation costs.
U.S. Pat. No. 5,599,373 relates to a sulphur-based, chemical soil-corrective or conditioner for agricultural use in the form of pellets, said product containing fly sulphur powder, at least 3% by weight of an inert compound selected from the group consisting of clay, bentonite, kaolin and mixtures thereof, and at least 0.5% by weight of a wetting agent. Other fertilizers, compositions and method of manufacture can be found in U.S. Pat. Nos. 5,599,373, 5,571,303 and 4,330,319.
Other issues may arise in relation to the dispersion of the actives from the compositions once applied to the field. For instance, in the case of granules, directly applied in the field or dispersed in a solution such as water and subsequently applied by spraying techniques, it may be difficult to note whether adequate or complete dispersion of the actives occurs in minimal time to obtain the desired concentration or whether adequate coverage has been achieved.
A hard pellet may be less friable but not sufficiently disperse the actives. The pellets found in prior art are either friable or do not provide optimum release of the actives. Thus, there are several problems associated in prior art with respect to the particle size, packing, transportation and dispersibilty of the product in the field and safety of the end user. Hence, there is a need to obtain a product with optimum hardness and with suitable dispersion of the actives.
OBJECT OF THE INVENTION:
An object of the invention is to provide a pellet with optimal hardness and dispersibility and a process for producing the same.
SUMMARY OF THE INVENTION:
The present invention discloses a cylindrical pellet and method of producing same comprising: micronized elemental sulphur having particles size less than 7 µm in diameter in the amount ranging from 78.0-82.0 %; a binder component in the amount ranging from 5 to 9 % by weight; a wetting agent in the amount ranging from 4 to 6 % by weight; a dispersing agent in the amount ranging from 4 to 6 % by weight; a solvent present in the amount ranging from 1 to 3 % by weight. The pellet having a mean particle domain size of for D10 is 5 to 8 µm and for D 50 is 25 to 35 µm and all in a form such that within a few minutes of contact with water the pellet disperses into particles with more than 98.0-99.6 % of said particles passing through a 75 µm mesh (US Standard Size) screen. The pellet of the present invention comprises wetting agent which may be from anionic surfactants such as alkyl aryl sulphonates preferably sodium salt of alkyl aryl sulfonate and dispersing agent may be from condensation products of phenol sulfonic acid preferably sodium salt of phenol sulfonic acid condensate.
The pellet of the present invention comprises optimum hardness to prevent friability and requisite water dispersibility to ensure quick and uniform release of the actives.
DETAILED DESCRIPTION OF THE INVENTION:
The present invention discloses a WDG (cylindrical pellet) comprising: micronized elemental Sulphur having the particle size less than 7 µm in diameter in the range of 78.0-82.0 % by weight.
The cylindrical pellets of the present invention comprise micronized elemental Sulphur, a binder, a wetting agent, a dispersing agent, a solvent, along with acceptable excipients.
The Sulphur of the present invention may be Sulphur 80% and preferably used in the range of 78.0 to 82.0% by weight in the composition.
The wetting agent of the present invention may be selected from anionic surfactant such as alkyl aryl sulphonate preferably sodium salt of alkyl aryl sulfonate.
The dispersing agent of the cylindrical pellets in the present invention may be selected from condensation product of phenol sulfonic acid preferably sodium salt of phenol sulfonic acid condensate.
The binder of the cylindrical pellets may be selected from non-water soluble binding agent comprising talcum powder or china clay; preferably talcum powder.
The binder is present in the range of 5 to 9 % w/w in the composition. Preferably, the binder is in the range of 6 to 8 % w/w. The wetting agent may be present in the range of 4 to 6% w/w in the composition, preferably 5% w/w. The dispersing agent may be present in the range of 4 to 6% w/w in the composition and the solvent may be present in the range of 1 to 3% w/w in the cylindrical pellet composition.
The cylindrical pellet of the present invention may have a mean particle domain size ranges from for D10 is 5 to 8 µm, preferably 5.5 to 7.8 µm and for D 50 is 25 to 35 µm, preferably 28 to 33 µm and all in a form such that within a few minutes of contact with water the pellet disperses into particles with more than 98.0-99.6 % of said particles passing through a 75 µm mesh (US Standard Size) screen.
The length of the pellet of the present invention may be in the range of 2 to 4 mm. The breadth of the pellet of the present invention may be in the range of 1.0 to 1.5 mm. The ratio of the length and breadth of the pellet of the present invention may be 2: 1.0 to 4:1.5.
The suspensibility of the pellet of the present invention may be in the range of 55-75% w/w and most preferred range of 60-70% w/w.
In an embodiment, the present invention discloses a process for preparing the cylindrical pellets of the present invention comprising the steps of:
(i) mixing binder, wetting agent, a dispersing agent with sulphur to obtain a mixture;
(ii) adding a solvent to the above mixture to obtain a dough;
(iii) extruding the dough of step (ii) through an extruder to obtain cylindrical pellets.
The process as claimed above, wherein the solvent comprising polar solvents; preferably the solvent may be selected from acetone or isopropyl alcohol or water or Ethyl Acetate.
In the present invention disclose the use of the pellets for their use in preventing injury to user and for the quick and uniform release of actives to the field.
The user as used in the present specification refers to the person who apply a cylindrical pellet composition of the present invention in the field.
In the present invention discloses the use of the pellets of the present invention for easy storage, handling and transport when compared with other existing WP composition or micro granules.
The present invention also discloses the use of the pellets of the present invention for decreasing less inhalation hazard to the applicator during pouring and mixing.
The present invention in another aspect discloses the use of the pellets of the present invention for where any hazard, if any due to WDG (cylindrical granules) can be measured more easily when compared with other existing WP composition or micro granules.
The present invention also discloses the use of the pellets of the present invention for decreasing skin and eye absorption when compared with other existing WP composition or micro granules.

The components of the composition acts in a synergistic manner which results in better optimal hardness and dispersibility.

Without being limited by theory the cylindrical pellet of the present invention is easy to store, handle and transport in comparison to other compositions. A cylindrical pellet is generally solid, without any small particles in the size range of length of the pellet of the present invention is in the range of 2 to 4 mm. The breadth of the pellet of the present invention is in the range of 1.0 to 1.5 mm, and therefore poses less inhalation hazard by the end user during pouring and mixing. The cylindrical pellets also cause less irritation in the skin and eyes and other toxic side effects.
Examples:
The present invention is illustrated herein by way of examples. The examples are merely meant for illustration and should not be construed as limiting the scope of the invention. All compositions are illustrative examples of the composition of the present invention.
Example 1: The different ingredient compositions
The compositions of the WDG Sulphur noodle comprises of the ingredients in compositions 1 to 4 as per the table 1.
Table 1. Compositions of the WDG Sulphur noodle of the present invention
Components Formula 1 Formula 2 Formula 3 Formula 4
Sulphur Powder Technical ( 100 % basis) 80.2 80.5 80.2 80.0
Wetting Agent (Sodium Salt of Alkyl aryl sulfonate) 5.0 5.0 5.0 5.0
Dispersing Agent (Sodium Salt of phenol sulfonic acid condensate) 5.0 5.0 5.0 5.0
Talcum Powder 8.0 8.0 8.0 -
China clay - - - 8.0
Isopropyl alcohol 2.0 - - -
Acetone - - - 2.0
Water - 2.0 - -
Ethyl Acetate - - 2.0 -
Total 100.2 100.5 100.2 100.0

Example 2. An illustrative process to manufacture WDG pellets of the present invention
The process to manufacture WDG sulphur pellets as disclosed in the present invention is carried out in primarily four steps including Pre-blending, Grinding or milling, Dough or mixture and reducing the particle size to result in Granules.
All the raw materials for the composition as described in the description are weighed and a pre-blend is made by blending.
The pre-blend is a wetting agent and a dispersing agent in the ranges described in the description is added to the pre-blend and mixed along with the solvent.
The composition is ground/milled at standard pressure as per standard operating procedures.
The composition is made into a homogenous dough mixture.
The composition is extruded to get the specified size and dried at standard temperatures. The composition is packed in airtight packaging.

Example 3.
The compositions described in the example 1 was prepared as per the process of example 2 and the following observations with respect to the parameters were made:
The particle size D10 in formula 1 is 7 µm, in formula 2 is 6 µm, in formula 3 is 7.3 µm and formula 4 is 6.8 µm. Further, particle size D50 in formula 1 is 30 µm, in formula 2 is 28 µm, in formula 3 is 29.8 µm and formula 4 is 31.2 µm. The WDG sulphur noodle of the above mentioned formulae when passes through the Wet Sieve test (75 µm sieve) confirmed with all regulatory parameters.
After the dough was extruded though the sieve and the dimensions (both outer dimension and length) of the cylindrical granules was measured. The dimension of the cylindrical granules produced from formula 1 was 1.1 - 1.4 mm outer dimension and length 2 - 4 mm, from formula 2 was 1.1 - 1.4 mm outer dimension and length 2 - 4 mm, from formula 3 was 1.1 - 1.4 mm outer dimension and length 2 - 4 mm and from formula 4 was 1.1 - 1.4 mm outer dimension and length 2 - 4 mm.
The concentration of the Sulphur in the WDG Sulphur noodle was examined and found that the concentration of sulphur in the compositions 1 to 4 were 80 % w/w, 80 % w/w, 80 % w/w, 80.2 % w/w respectively.
Further, the suspensibility of the compositions 1-4 were 65 % w/w, 68 % w/w, 63 % w/w and 64 % w/w respectively. Furthermore, the pH (2% Aq.) in compositions 1-4 were found to be 6.0 - 8.0, 6.0 - 8.0, 6.0 - 7.5 and 6.0 - 7.5 respectively.

Table 2. Characteristics of the composition of the present invention
Parameter Composition 1 Composition 2 Composition 3 Composition 4
Particle Size (D10) 7 µm 6 µm 7.3 µm 6.8 µm
(D50) 30 µm 28 µm 29.8 µm 31.2 µm
Wet Siev test, Material Passing Through (75 µm Sieve ) 99 %w/w 99.5 %w/w 99.1 %w/w 99.1%w/w
Dimension of Cylindrical granules (Outer Diameter) 1.1 - 1.4 mm 1.1 - 1.4 mm 1.1 - 1.4 mm 1.1 - 1.4 mm
(Length)
2 - 4 mm
2 - 4 mm
2 - 4 mm
2 – 4 mm
Sulphur 80 %w/w 80 %w/w 80 %w/w 80.2%w/w
Suspensibility 65 % w/w 68 % w/w 63 % w/w 64% w/w
pH (2%Aq.) 6.0 - 8.0 6.0 - 8.0 6.0 - 7.5 6.0 – 7.5

We Claim:
1. A cylindrical pellet comprising
a. micronized elemental sulphur particles having the particles size less than 7 µm in diameter in the amount ranging from 78.0 to 82.0% by weight;
b. a binder component in the amount ranging from 5 to 9% by weight;
c. a wetting agent in the amount ranging from 4 to 6% by weight;
d. a dispersing agent in the amount ranging from 4 to 6% by weight; and
e. a solvent present in the amount ranging from 1 to 3% by weight,
characterized in that the pellet having a mean particle domain size of 5 to 35 µm disperses into particles within few minutes of contact with water and more than 98.0-99.6% of said dispersed particles passing through a 75 µm mesh screen and possesses optimum hardness to prevent friability and optimum dispersibility.

2. The cylindrical pellet as claimed in claim 1, wherein the binder is selected from the group consisting of non-water soluble binder, talcum powder or china clay preferably talcum powder.

3. The cylindrical pellet as claimed in claim 1, wherein the wetting agent is selected from the group consisting of anionic surfactant, alkyl aryl sulphonate preferably sodium salt of alkyl aryl sulfonate.

4. The cylindrical pellet as claimed in claim 1, wherein the dispersing agent is selected from the group consisting of condensation product of phenol sulfonic acid preferably sodium salt of phenol sulfonic acid.

5. The cylindrical pellet as claimed in claim 1, wherein the solvent is selected from group consisting of polar solvent preferably acetone or isopropyl alcohol or water or ethyl acetate.

6. The cylindrical pellet as claimed in claim 1, wherein the mean particle domain size for D10 ranges from 5 to 8 µm preferably 5.5 to 7.8 µm and for D50 ranges from 25 to 35 µm preferably 28 to 33 µm.

7. The cylindrical pellet as claimed in claim 1, wherein the length of the pellet may be in the range of 2 to 4 mm; breadth of the pellet may be in the range of 1.0 to 1.5 mm and the ratio of the length and breadth of the pellet may be 2.0:1.0 to 4.0:1.5.

8. The cylindrical pellet as claimed in claim 1, wherein the suspensibility of the pellet may be in the range of 55-75% w/w preferably in the range of 60-70% w/w.

9. A process for preparing the cylindrical pellet as claimed in claim 1, wherein the said process comprises the steps of:
i. mixing binder, wetting agent, dispersing agent with sulphur to obtain a mixture;
ii. adding a solvent to the mixture resulted from step (i) to obtain a dough; and
iii. extruding the dough of step (ii) through an extruder to obtain cylindrical pellets.
10. The cylindrical pellet as claimed in claim 1 for its use in preventing injury to user and releasing actives to the field.