DESC:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]

“PLANT NUTRIENT CARRYING SUPER WATER ABSORBENT POLYMER PRODUCT AND PROCESS OF PREPARATION THEREOF”

Hindustan Gum & Chemicals Ltd., an Indian Company at: Birla Colony, Bhiwani 127021, Haryana, India

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

Field of the Invention:
[01] The present invention provides a plant nutrient carrying super water absorbent polymer product which includes a synthetic polymeric material, a natural polymeric material grafted to the synthetic polymeric material and a plant nutrient material. The plant nutrient carrying super water absorbent polymer can be mixed with soil and increases the water retention capacity of the soil. The invention also relates to a process for preparing the plant nutrient carrying super water absorbent polymer product.

Background of the Invention:
[02] Super water absorbent polymer product is an extremely hydrophilic polymer that is crosslinked into a three-dimensional network and has a unique ability to absorb at least a few hundred times of water as compared to its original dry weight. Super water absorbent polymer product based purely on acrylic acid or acrylate polymers have good absorption, retention and permeability properties. However, the super water absorbent polymer product exclusively based on acrylic acid or acrylate polymer, has an inadequate level of biodegradability. Thus, use of super water absorbent polymer product exclusively based on acrylic acid or acrylate polymer for agricultural purposes is disadvantageous.

[03] In some cases, super water absorbent polymer product has been made by admixing acrylic acid or acrylate polymers with natural polymers. The admixture of acrylic acid or acrylate polymers and natural polymers does not however increase biodegradability of the acrylic acid polymers. Thus, use of super water absorbent polymer product comprising admixture of acrylic acid or acrylate polymer and natural polymers for agricultural purposes is also disadvantageous.

[04] In some cases, natural polymers have been co-polymerized with the acrylic acid or acrylate polymers to form the super water absorbent polymer product. However, a lot of difficulties have been faced while adopting this route. By way of example, a weight percentage of the natural polymers as determined on the basis of a total weight percentage of the super water absorbent is limited. Typically, the weight percentage of the natural polymers as determined on the basis of the total weight percentage of the super water absorbent is about 5 to 15 wt.%. By way of another example, attempts to increase the weight percentage of the natural polymers beyond about 15 wt.% results in a mass and more particularly a gel material which is difficult to process.

[05] Thus, there exists a need to provide a super water absorbent polymer product which is easily degradable having sufficiently high water absorbing capacity. In particular, there exists a need to provide a super water absorbent polymer product which includes a synthetic polymeric material and more than about 15 wt.% of a natural polymer.

[06] Additionally, the plant requires micro-nutrient such as zinc to grow. However, the traditional existing acrylic acid or acrylate based polymers do not full fill this requirement.

[07] Additionally, the plant requires a combination of zinc and at least one of sulfur, calcium, nitrogen, phosphorous, and potassium to grow. However, the traditional existing acrylic acid or acrylate based polymers do not full fill this requirement.

[08] Thus, there exists a need to provide a super water absorbent polymer product which is easily degradable, which delivers zinc a micro-nutrient optionally along with at least one of sulfur, calcium, nitrogen, phosphorous, and potassium without drastically disturbing the water absorbing capacity of the super water absorbent polymer product.

Summary of the invention:
[09] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key or essential features.

[010] Accordingly, the present invention provides a plant nutrient carrying super water absorbent polymer product comprising a grafted co-polymer comprising polyglucosyl polymer chain linked to at least one acrylic acid or acrylate polymer chain; and a Zinc-ethylenediaminetetraacetic acid (Zn-EDTA) complex loaded or attached to the grafted co-polymer.

[011] Accordingly, the present invention provides a plant nutrient carrying super water absorbent polymer product comprising a grafted co-polymer comprising polyglucosyl polymer chain linked to at least one acrylic acid or acrylate polymer chain; a Zn-EDTA complex, and at least one of sulfur, calcium, nitrogen, phosphorous, and potassium loaded or attached to the grafted co-polymer.

[012] The invention furthermore provides a process for preparing a super water absorbent polymer product, said process comprising mixing at least one acrylic acid or acrylate monomer, a polyglucosyl polymer, a cross-linking agent, and a Zn-EDTA complex under a polymerizing condition to obtain the super water absorbent polymer product.

[013] The invention furthermore provides a process for preparing a super water absorbent polymer product, said process comprising mixing at least one acrylic acid or acrylate monomer, a polyglucosyl polymer, a cross-linking agent, a Zn-EDTA complex, and at least one of sulfur, calcium, nitrogen, phosphorous, and potassium under a polymerizing condition to obtain the super water absorbent polymer product.

[014] To further clarify the advantages and features of the invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings.

Detailed Description of the invention:
[015] For the purpose of promoting an understanding of the principles of the invention, specific language will be used for describing the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications being contemplated as would normally occur to one skilled in the art to which the invention relates. It will be understood by those skilled in the art that the foregoing general description and the following detailed description are explanatory of the invention and are not intended to be restrictive thereof.

[016] In the Applicant’s co-pending application numbered 202211047814, there has been described a super water absorbent polymer product comprising: at least one acrylic acid or acrylate polymer chain; and at least one polyglucosyl polymer chain linked to the at least one acrylic acid or acrylate polymer chain. The polyglucosyl polymer chain is present in an amount in the range of about 10 to about 50% by weight of the super water absorbent polymer product. The polyglucosyl polymer chain comprises a modified starch. The polyglucosyl polymer chain being selected such that an aqueous solution comprising 50% w/v of the polyglucosyl polymer chain has viscosity in the range of 5000-50000 cps at a room temperature. The super water absorbent polymer product as described above has sufficient bio-degradability, has good water absorption capacity, has good water retention capacity, has good water permeability, and does not get converted into a gel material (during production).

[017] In the Applicant’s co-pending application numbered 202211056563, there has been described a super water absorbent polymer product comprising: at least one acrylic acid or acrylate polymer chain; at least one polyglucosyl polymer chain linked to the at least one acrylic acid or acrylate polymer chain; and a hydroxyapatite. The polyglucosyl polymer chain is present in an amount in the range of about 10 to about 50% by weight of the super water absorbent polymer product. The polyglucosyl polymer chain comprises a modified starch. The polyglucosyl polymer chain being selected such that an aqueous solution comprising 50% w/v of the polyglucosyl polymer chain has viscosity in the range of 5000-50000 cps at a room temperature. The hydroxyapatite comprises un-modified hydroxyapatite and modified hydroxyapatite and is present in an amount of about 1 to 10 % by weight. The super water absorbent polymer product as described above has sufficient bio-degradability, has good water absorption capacity, has good water retention capacity, has good water permeability, does not get converted into a gel material (during production), and delivers at least one compound selected from the group comprising calcium, nitrogen, phosphorous, and potassium.

[018] Accordingly, the present invention provides a super water absorbent polymer product comprising a grafted co-polymer and a Zinc-ethylenediaminetetraacetic acid (Zn-EDTA) complex. In an embodiment of the invention, the Zn-EDTA complex is loaded or attached to the grafted co-polymer. In another embodiment of the invention, the grafted co-polymer comprises polyglucosyl polymer chain which is further linked to at least one acrylic acid or acrylate polymer chain.

[019] According to one aspect of the invention there is provided a plant nutrient carrying super water absorbent polymer product comprising a grafted co-polymer comprising polyglucosyl polymer chain linked to at least one acrylic acid or acrylate polymer chain and a Zn-EDTA complex loaded on the grafted co-polymer and at least one of the sulfur, calcium, nitrogen, phosphorus, and potassium loaded or attached to the grafted co-polymer.

[020] According to yet another aspect of the invention, there is provided a process for preparing a super water absorbent polymer product, said process comprising mixing at least one acrylic acid or acrylate monomer, a polyglucosyl polymer, a cross-linking agent, and a Zn-EDTA complex under a polymerizing condition to obtain the super water absorbent polymer product.

[021] According to still another aspect of the invention, there is provided a process for preparing a super water absorbent polymer product, said process comprising mixing at least one acrylic acid or acrylate monomer, a polyglucosyl polymer, a cross-linking agent, a Zn-EDTA complex, and at least one of sulfur, calcium, nitrogen, phosphorous, and potassium under a polymerizing condition to obtain the super water absorbent polymer product.

[022] In still another embodiment of the invention, the Zn-EDTA complex is present in an amount in the range of about 0.01 to about 0.1% by weight of the plant nutrient carrying super water absorbent polymer product.

[023] In still another embodiment of the invention, the polyglucosyl polymer chain is present in an amount in the range of about 18% to about 90% by weight of the grafted co-polymer. In an embodiment of the invention, the grafted co-polymer comprises a cross-linking agent in an amount of about 0.1 to about 10 % by weight. Thus, a remaining part of the grafted co-polymer comprises acrylic acid or acrylate polymer chain.

[024] A glycosyl group is a univalent free radical or substituent structure obtained by removing the hemiacetal hydroxyl group from the cyclic form of a monosaccharide and, by extension, of a lower oligosaccharide. The glycosyl group has the chemical structure - I as shown below:

[025] Two or more (preferably more) glycosyl groups can be linked to one another to form a poly glycosyl polymer chain.

[026] In a preferred aspect of the invention, the poly glycosyl polymer chain substantially resembles the structure of at least one of an Amylose (having the chemical structure II), an Amylopectin (having the chemical structure III), pullulan (having well known chemical structure, which is not shown), glycogen (having well known chemical structure, which is not shown), dextran (having well known chemical structure, which is not shown), chrysolaminarin (having well known chemical structure, which is not shown), curdlan (having well known chemical structure, which is not shown), laminarin (having well known chemical structure, which is not shown), lentinan (having well known chemical structure, which is not shown), lichenin (having well known chemical structure, which is not shown), pleuran (having well known chemical structure, which is not shown), and zymosan (having well known chemical structure, which is not shown).
… II
…III

[027] In a preferred embodiment of the invention, starch can be used as the source of the poly glycosyl polymer chain. In an embodiment of the invention, a modified starch can be used as the source of polyglucosyl polymer chain. Modified starches are used in the application are not native starches. Chemical modification(s) of native starch is required to obtain modified starch.

[028] The relevant modification of the native starch can be, separately or in combination, fragmentations (hydrolysis, oxidation, enzymatic), bleaching, oxidation, esterification, etherification or phosphorylation of one or more of the hydroxyl groups of the a-D-glucopyranosyl units or crosslinking using polyfunctional agents.

[029] In an embodiment of the invention, the modified starch is selected from a group comprising an enzymatically modified starch, dextrinised starch, an acid treated starch, an alkali treated starch, a bleached starch, an oxidized starch, mono-starch phosphate, di-starch phosphate, phosphated di-starch phosphate, acetylated distarch phosphate, starch acetate, hydroxypropyl starch, hydroxypropyl distarch phosphate, starch sodium octenyl succinate, acetylated oxidized starch, and starch aluminum octenyl succinate.

[030] The term dextrinised starch or dextrin roasted starch comprises by way of non-limiting example, starches that are obtained by dry heating or roasting of native starch with hydrochloric acid or ortho-phosphoric acid in heated and/or agitated vessels. The final dextrin roasted starch is obtained by drying and include starches identified by International Numbering System (INS) number 1400.

[031] The term acid treated starch comprises by way of non-limiting example, starches that are obtained by treating a slurry or a suspension of native food starch with dilute hydrochloric acid, ortho-phosphoric acid, or sulphuric acid and include starches identified by INS number 1401.

[032] The term alkali treated starch comprises by way of non-limiting example, starches that are obtained by treating a suspended solution of native food starches with sodium hydroxide or potassium hydroxide and include starches identified by INS number 1402.

[033] The term bleached starch comprises by way of non-limiting example, starches that are obtained by treating a suspended solution of native food starches with Peracetic acid and/or hydrogen peroxide, or sodium hypochlorite, sodium chlorite, sulfur dioxide, alternative permitted forms of sulphites, potassium permanganate, or ammonium persulfate and include starches identified by INS number 1403.

[034] The terms oxidized starch comprises by way of non-limiting example, starches that are obtained by treatment of food starch with sodium hypochlorite and include starches that are identified by INS number 1404.

[035] The term enzymatically modified starch comprises by way of non-limiting example, starches that are obtained by treating a suspension of native food starch with one or more food-grade amyolytic-enzymes (e.g., a-amylase (E.C. 3.2.1.1), ß-amylase (3.2.1.2), glucoamylase (3.2.1.3), isoamylase (3.2.1.68), pullulanase (E.C. 3.2.1.41)) and include starches that are identified by INS number 1405.

[036] The term mono-starch phosphate comprises by way of non-limiting example, starches that are obtained by esterification/crosslinking of unmodified food starch with ortho-phosphoric acid, or sodium or potassium orthophosphate, or sodium tripolyphosphate and include starches that are identified by INS number 1410.

[037] The term di-starch phosphate comprises by way of non-limiting example, starches that are obtained by crosslinking of unmodified food starch with sodium trimetaphosphate or phosphorus oxychloride and include starches that are identified by INS number 1412.

[038] The term phosphated di-starch phosphate comprises by way of non-limiting example, starches that are obtained by esterification/crosslinking of unmodified food starch with sodium trimetaphosphate or phosphorus oxychloride combined with esterification with orthophosphoric acid, or sodium or potassium orthophosphate, or sodium tripolyphosphate and include starches that are identified by INS number 1413.

[039] The term acetylated distarch phosphate comprises by way of non-limiting example, starches that are obtained by esterification/crosslinking of unmodified food starch with sodium trimetaphosphate or phosphorus oxychloride combined with esterification with acetic anhydride or vinyl acetate and include starches that are identified by INS number 1414.

[040] The term starch acetate comprises by way of non-limiting example, starches that are obtained by esterification of food starches with acetic anhydride or vinyl acetate and include starches that are identified by INS number 1420.

[041] The term hydroxypropyl distarch phosphate by way of non-limiting example, starches that are obtained by esterification of unmodified food starch with sodium trimetaphosphate or phosphorus oxychloride combined with etherification by propylene oxide and include starches that are identified by INS number 1422.

[042] The term starch sodium octenyl succinate comprises by way of non-limiting example, starches that are obtained by treatment of unmodified food starch with Octenylsuccinic anhydride and either sodium hydroxide or sodium carbonate as a pH buffer for neutralization and include starches that are identified by INS number 1450.

[043] The term acetylated oxidized starch comprises by way of non-limiting example, starches that are obtained by treatment of food starch with sodium hypochlorite followed by esterification with acetic anhydride and include starches that are identified by INS number 1451.

[044] The term Starch aluminum octenyl succinate comprises by way of non-limiting example, starches that are identified by INS number 1452.

[045] In an embodiment of the invention, the polyglucosyl polymer chain is selected such that an aqueous solution comprising 50% w/v of the polyglucosyl polymer chain has viscosity in the range of 5000-50000 cps at a room temperature. In an embodiment of the invention, an aqueous solution comprising 50% w/v of dextrinized starch having viscosity in the range of 5000-50000 cps at a room temperature is used as the source of the polyglucosyl polymer chain.

[046] Modified starches are used in applications requiring special properties not attainable by native starches. Chemical modifications of native starches are often performed, in an aqueous suspension under controlled conditions of pH, time and temperature, unless otherwise indicated in the description of the respective annex. After sufficient reaction time, the modified starch is recovered by filtration or centrifugation, washed with water.

[047] The relevant modification reactions can be, separately or in combination, fragmentations (hydrolysis, oxidation, enzymatic), bleaching, oxidation, esterification, etherification or phosphorylation of one or more of the hydroxyl groups of the a-D-glucopyranosyl units or crosslinking using poly functional agents.

[048] Hydroxyapatite (HA) is a naturally occurring mineral form of calcium apatite with the formula Ca5(PO4)3(OH) and a ceramic material which forms the mineral phase of bone. It is comprised primarily of calcium and phosphate at a respective ratio of 1:67.

[049] The term hydroxypropyl starch comprises by way of non-limiting example, starches that are obtained by etherification of unmodified food starch with propylene oxide and include starches that are identified by INS number 1440.

[050] In an embodiment of the invention, the acrylic acid or acrylate polymer chain comprises acrylic acid monomer. In another embodiment of the invention, the acrylic acid or acrylate polymer chain comprises acrylic acid monomer and a neutralizing agent. The neutralizing agent is having an alkali metal cation and potassium metal cation. The neutralizing agent is selected from the group of, but not limited to, sodium hydroxide, potassium hydroxide (KOH), and calcium hydroxide. In an embodiment of the invention, the acrylic acid or acrylate polymer chain comprises acrylic acid monomer neutralized to an extent of 40% to 90% by the neutralizing agent.

[051] In an embodiment of the invention, cross-linkers are methylene bis- acrylamide (MBA) or Trimethylolpropane triacrylate (TMPTA) ) or Trimethylolpropane ethoxylate triacrylate (EO-TMPTA) or polyethylene glycol diacrylate (PEGDA).

[052] In an embodiment of the invention, polymerization initiator is added to initiate the polymerization reaction. The polymerization initiator is selected from the group of, but not limited to, ammonium persulphate, potassium persulphate and ammonium peroxydisulphate. The polymerization initiator is added at a temperature in the range from about 40°C to 80°C.

[053] In an embodiment of the invention, the polymerization initiator is present in an amount of about 0.01 to about 2% by weight.

[054] In an embodiment of the invention, the acrylic acid or acrylate polymer chain comprises acrylic acid monomer neutralized to an extent of 40 to 90% by the neutralizing agent.

[055] In an embodiment of the invention, the grafted co-polymer comprises a cross-linking agent in an amount of about 0.1 to about 10 % by weight.

[056] According to another aspect of the invention, there is provided a plant nutrient carrying super water absorbent polymer product comprising a grafted co-polymer comprising polyglucosyl polymer chain linked to at least one acrylic acid or acrylate polymer chain; a Zn-EDTA complex, and at least one of sulfur, calcium, nitrogen, phosphorous, and potassium loaded or attached to the grafted co-polymer.

[057] In an embodiment of the invention, there is provided a plant nutrient carrying super water absorbent polymer product comprising a grafted co-polymer comprising polyglucosyl polymer chain linked to at least one acrylic acid or acrylate polymer chain; a Zn-EDTA complex, and potassium loaded or attached to the grafted co-polymer.

[058] To load potassium on the grafted co-polymer, in accordance with an embodiment of the invention, the acrylic acid or acrylate polymer chain is neutralized with a neutralizing agent which is potassium hydroxide.

[059] In an embodiment of the invention, there is provided a plant nutrient carrying super water absorbent polymer product comprising a grafted co-polymer comprising polyglucosyl polymer chain linked to at least one acrylic acid or acrylate polymer chain; a Zn-EDTA complex, a calcium containing compound and a phosphorous containing compound loaded or attached to the grafted co-polymer.

[060] In an embodiment of the invention, there is provided a plant nutrient carrying super water absorbent polymer product comprising a grafted co-polymer comprising polyglucosyl polymer chain linked to at least one acrylic acid or acrylate polymer chain; a Zn-EDTA complex, potassium, a calcium containing compound and a phosphorous containing compound loaded or attached to the grafted co-polymer.

[061] In an embodiment of the invention, hydroxyapatite acts as a source of calcium containing compound and a phosphorous containing compound. In an embodiment of the invention, the hydroxyapatite used has a size in the range of 1 to 30 nm. In an embodiment of the invention, the hydroxyapatite is present in an amount of about 1 to 10 % by weight.

[062] In an embodiment of the invention, there is provided a plant nutrient carrying super water absorbent polymer product comprising a grafted co-polymer comprising polyglucosyl polymer chain linked to at least one acrylic acid or acrylate polymer chain; a Zn-EDTA complex, a calcium containing compound, a nitrogen containing molecule and a phosphorous containing compound loaded on the grafted co-polymer.

[063] In an embodiment of the invention, there is provided a plant nutrient carrying super water absorbent polymer product comprising a grafted co-polymer comprising polyglucosyl polymer chain linked to at least one acrylic acid or acrylate polymer chain; a Zn-EDTA complex, potassium, a calcium containing compound, a nitrogen containing molecule and a phosphorous containing compound loaded on the grafted co-polymer.

[064] In an embodiment of the invention, modified hydroxyapatite acts as a source of nitrogen containing molecule, calcium containing compound, and a phosphorous containing compound. In an embodiment of the invention, the modified hydroxyapatite used has a size in the range of 1 to 60 nm. In an embodiment of the invention, the modified hydroxyapatite contains urea which is a source of nitrogen. The modified hydroxyapatite is present in an amount of about 1 to 10% by weight of plant nutrient carrying super water absorbent polymer.

[065] In an embodiment of the invention, there is provided a plant nutrient carrying super water absorbent polymer product comprising a grafted co-polymer comprising polyglucosyl polymer chain linked to at least one acrylic acid or acrylate polymer chain; a Zn-EDTA complex, and a sulfur containing compound loaded on the grafted co-polymer.

[066] In an embodiment of the invention, there is provided a plant nutrient carrying super water absorbent polymer product comprising a grafted co-polymer comprising polyglucosyl polymer chain linked to at least one acrylic acid or acrylate polymer chain; a Zn-EDTA complex, a sulfur containing compound, and potassium loaded on the grafted co-polymer.

[067] In an embodiment of the invention, there is provided a plant nutrient carrying super water absorbent polymer product comprising a grafted co-polymer comprising polyglucosyl polymer chain linked to at least one acrylic acid or acrylate polymer chain; a Zn-EDTA complex, a sulfur containing compound, a calcium containing compound and a phosphorous containing compound loaded on the grafted co-polymer.

[068] In an embodiment of the invention, there is provided a plant nutrient carrying super water absorbent polymer product comprising a grafted co-polymer comprising polyglucosyl polymer chain linked to at least one acrylic acid or acrylate polymer chain; a Zn-EDTA complex, a sulfur containing compound, potassium, a calcium containing compound and a phosphorous containing compound loaded on the grafted co-polymer.

[069] In an embodiment of the invention, hydroxyapatite acts as a source of calcium containing compound and a phosphorous containing compound. In an embodiment of the invention, the hydroxyapatite used has a size in the range of 1 to 30 nm. In an embodiment of the invention, the hydroxyapatite is present in an amount of about 2 to 8 % by weight. In an embodiment of the invention, modified hydroxyapatite acts as a source of nitrogen containing molecule, calcium containing compound, and the phosphorous containing compound. In an embodiment of the invention, the modified hydroxyapatite used has a size in the range of 1 to 60 nm. In an embodiment of the invention, the modified hydroxyapatite contains urea which is a source of nitrogen. The modified hydroxyapatite is present in an amount of about 1 to 10% by weight of plant nutrient carrying super water absorbent polymer.

[070] In an embodiment of the invention, there is provided a plant nutrient carrying super water absorbent polymer product comprising a grafted co-polymer comprising polyglucosyl polymer chain linked to at least one acrylic acid or acrylate polymer chain; a Zn-EDTA complex, and a sulfur containing compound, a calcium containing compound, a phosphorous containing compound and a nitrogen containing molecule loaded or attached to the grafted co-polymer.

[071] In an embodiment of the invention, there is provided a plant nutrient carrying super water absorbent polymer product comprising a grafted co-polymer comprising polyglucosyl polymer chain linked to at least one acrylic acid or acrylate polymer chain; a Zn-EDTA complex, a sulfur containing compound, a calcium containing compound, a phosphorous containing compound, a nitrogen containing molecule and potassium loaded or attached to the grafted co-polymer.

[072] In another embodiment of the invention, the zinc containing compound is a Zn-EDTA complex. In still another embodiment of the invention, the zinc containing compound or the Zn-EDTA complex is present in an amount in the range of about 0.01 to about 0.1% by weight of the plant nutrient carrying super water absorbent polymer product.

[073] To load potassium on the grafted co-polymer, in accordance with an embodiment of the invention, the acrylic acid or acrylate polymer chain is neutralized with a neutralizing agent which is potassium hydroxide.

[074] In an embodiment of the invention, the sulfur containing compound is an acrylamidoalkanesulfonic acid of formula I:

wherein R1 is hydrogen or a lower alkyl radical and each of R1, R2, R3, R4, R5 and R6 is individually hydrogen or a hydrocarbon radical.

[075] The term “lower alkyl radical” denotes alkyl radicals containing up to about 10 carbon atoms, preferably up to about 7 carbon atoms.

[076] The term “hydrocarbon radical” comprises by way of non-limiting example, alkyl, and cycloalkyl and aryl radicals. As used herein, the term hydrocarbon radical also includes radicals containing other atoms and substituents which do not detract substantially from the hydrocarbon characteristics of the radical. Suitable substituents of this type include, for example, ether, ester, nitro and halogen radicals; also included are heterocyclic radicals such as the pyridine radical.

[077] In an embodiment of the invention, the acrylamidoalkanesulfonic acid of formula I is2-acrylamido-2-methyl-1-propanesulfonic acid.

[078] In an embodiment of the invention, the acrylamidoalkanesulfonic acid of formula I is present in an amount ranging from 5 to 20 wt.% of the acrylic acid or acrylate polymer chain.

[079] In an embodiment of the invention, the plant nutrient carrying super water absorbent polymer product has zinc, which is a micro-nutrient, as compared to super water absorbent polymer product which is devoid of the same. Also, since Zn-EDTA-complex which is easily substitutable and up-table by the plant, there is a substantial advantage.

[080] In an embodiment of the invention, the plant nutrient carrying super water absorbent polymer product comprising a combination of Zn-EDTA complex and sulfur has modified texture as compared to a plant nutrient carrying super water absorbent polymer product which comprises Zn-EDTA complex and is devoid of the sulfur containing compound.

[081] In an embodiment of the invention, the plant nutrient carrying super water absorbent polymer product comprising a combination of Zn-EDTA complex and potassium delivers more amount of plant nutrient as compared to (a) a plant nutrient carrying super water absorbent polymer product which comprises Zn-EDTA complex and is devoid of potassium as well as (b) a plant nutrient carrying super water absorbent polymer product which comprises potassium and is devoid of Zn-EDTA complex.

[082] In an embodiment of the invention, the plant nutrient carrying super water absorbent polymer product comprising a combination of Zn-EDTA complex, sulfur and potassium delivers more amount of plant nutrient as compared to (a) a plant nutrient carrying super water absorbent polymer product which comprises Zn-EDTA complex and is devoid of sulfur potassium as well as (b) a plant nutrient carrying super water absorbent polymer product which comprises sulfur and potassium and is devoid of Zn-EDTA complex.

[083] In an embodiment of the invention, the plant nutrient carrying super water absorbent polymer product comprising a combination of Zn-EDTA complex, calcium and phosphorous delivers more amount of plant nutrient as compared to (a) a plant nutrient carrying super water absorbent polymer product which comprises Zn-EDTA complex and is devoid of calcium and phosphorous as well as (b) a plant nutrient carrying super water absorbent polymer product which comprises calcium and phosphorous and is devoid of an Zn-EDTA complex.

[084] In an embodiment of the invention, the plant nutrient carrying super water absorbent polymer product comprising a combination of Zn-EDTA complex, sulfur, potassium, calcium, phosphorous and nitrogen delivers all the 3 macro-nutrients as well as two minor nutrients.

Example 1: Preparation of Zn-EDTA Complex:
[085] Ethylenediaminetetraacetic acid (EDTA) disodium salt dihydrate (20 g, 0.054 mol) taken in a beaker, 100 mL water added and stirred for 30 min. After that, 10 mL liquid ammonia solution (25%) was added slowly into the mixture. After 15 min the solution becomes clear, and then 4.4 g ZnO was added and stirred for almost 3 h until a clear solution of Zn-EDTA was formed. The solution was heated at 90 °C to remove the solvent, and the white powder of Zn-EDTA complex was obtained.

Example 2: Micro-Batch (Lab) Scale process for preparation of grafted co-polymer
[086] The lab-scale process for preparing grafted co-polymer involved mixing the acrylic acid monomer, different types of starches in amount of about 20% of the grafted co-polymer (in the form of aqueous solution comprising 50% w/v of different types of starches), a cross linker, and a polymerization initiator in a kettle.

[087] Lab scale process was performed using different types of polyglucosyl polymers, typically native starches or modified starches such as, Guar Gum, Carboxy methyl Guar Gum, Oxidized Guar Gum, Sesbania Gum, Carboxymethyl Cellulose, Carboxymethyl Tamarid, Cassia Tora Gum, Topica Starch, Carboxy Methyl Starch Oxidized Starch/ Thin Boiling Starch, Maize Starch and Dextrinized Starch. The temperature was maintained at about 65°C. The acrylic acid monomer taken in these experiments was neutralized using potassium hydroxide to an extent of 90%. The cross-linker used in these examples was Trimethylolpropane triacrylate (TMPTA). The amount of cross-linker used was 0.5 wt% of the weight of the grafted co-polymer. The polymerization initiator was Ammonium persulphate and an amount of initiator used was 0.5 wt%. The results thus obtained is tabulated in Table 1 provided herein below:

Table 1: Results of Experiment 1
S.No. Name / Type /source of polyglucosyl polymer Absorbency value
1 Guar Gum Polymer not formed
2 Carboxy methyl Guar Gum Uniform Polymer not formed
3 Oxidized Guar Gum Uniform Polymer not formed
4 Sesbania Gum Polymer not formed
5 Carboxymethyl Cellulose Uniform Polymer not formed
6 Carboxymethyl Tamarid Uniform Polymer not formed
7 Cassia Tora Gum Polymer not formed
8 Topica Starch Polymer not formed
9 Carboxy Methyl Starch Uniform Polymer formed
10 Oxidized Starch/ Thin Boiling Starch Uniform Polymer not formed
11 Maize Starch Uniform Polymer not formed
12 Dextrinized Starch Uniform Polymer formed

All of the “Sources of polyglucosyl polymer indicated in Table 1 were obtained from SHAANXI HAIBO BIOTECHNOLOGY CO., LTD. No.11 Tangyan South Road, Xian, Shaanxi, China.

Example 3: Incorporation of Zn-EDTA complex into super water absorbent polymer product:
[088] In lab scale the reaction is performed using 20-30 g modified starch (Dextrinized starch), 30-50 g acrylic acid monomer, sodium or potassium hydroxide (40-80% neutralization), 0.1-0.5wt% of a suitable crosslinker like methylene bis- acrylamide (MBA) or Trimethylolpropane triacrylate (TMPTA) ) or Trimethylolpropane ethoxylate triacrylate (EO-TMPTA) or polyethylene glycol diacrylate (PEGDA), and Zn-EDTA complex as obtained in Example 1 in a solvent (wherein the amount is about 0.025 wt% with respect to super water absorbent polymer product). All the raw materials are mixed in a reaction kettle first having 20-50% solid content in water medium, followed by addition of persulphate-based initiator (0.1-1.0 wt %) at a temperature range of 60-80 °C to initiate the polymerization reaction. After completion of the polymerization reaction, Zn-EDTA containing super absorbent polymer is obtained which is cooled to room temperature and cut into small pieces for drying in a hot air oven at 65-70°C, overnight. The Zn-EDTA containing super absorbent polymer is grinded to have particle size of 600-1200 microns. The water absorbance was recorded to be 140-170 g/g. The pH and moisture content was found to be 6.4-7.5 and 1.8-2.6% respectively.

Example 4: Incorporation of Zn-EDTA complex into super water absorbent polymer product:
[089] The same concept is applied for 7 kg batch process in CKR-10, where 500-1000 g Modified starch (Dextrinized starch), 1000-2000 g acrylic acid monomer (40-80% neutralized), 0.1-0.5wt % of a suitable crosslinker, Zn-EDTA complex as obtained in Example 1 in a solvent (wherein the amount is about 0.04-0.05 wt% with respect to super water absorbent polymer product) and 0.1-0.5 wt % initiator is used inside the CKR batch reactor instead of kettle having 30-50% solid content in water medium. The porous Zn-EDTA containing superabsorbent polymer obtained is dried in a tray dryer using up flow and down flow of hot air at a temperature range of 120-160°C for 30-90 min, followed by subsequent grinding of the dried porous Zn-EDTA containing super absorbent polymer to get granular Zn-EDTA containing super absorbent polymer having particle size of 600-1200 microns. The water absorbance was recorded to be 135-165 g/g. The pH and moisture content was found to be 7.2-7.6 and 2.1-2.5% respectively.

Example 5: Incorporation of Zn-EDTA into super water absorbent polymer product:
[090] In another example, a continuous process for preparation of Zn-EDTA containing super absorbent polymer comprises the steps of:
a) neutralising an acrylic acid with an alkali hydroxide at a temperature of 10-20° C to a degree of neutralization in the range of 40-90%;
b) mixing a crosslinker such as methylene bis- acrylamide (MBA) or Trimethylolpropane triacrylate (TMPTA) or Trimethylolpropane ethoxylate triacrylate (EO-TMPTA) or polyethylene glycol diacrylate (PEGDA) (0.25wt % of the super water absorbent polymer) to the neutralized acrylic acid to obtain a first reaction mass;
c) preparing an aqueous solution of modified starch (Dextrinized starch) (50 wt% of the super water absorbent polymer); wherein the aqueous solution comprising 50% w/v of the dextrinized starch has a viscosity in the range of 5000-50000 cps at a room temperature;
d) mixing the crosslinker to the aqueous solution of dextrinized starch to obtain a second reaction mass;
e) mixing the first reaction mass with the second reaction mass at 30-80°C and further adding a mixed initiator system comprising of 0.02-0.10 wt% of redox including the hydrogen peroxide solution, sodium ascorbate ammonium peroxydisulfate (APS) / Potassium persulphate (KPS) solution (1-3 L/h) for preparing a grafting co-polymer containing sulfur;
f) incorporating Zn-EDTA solution (0.09 wt.% with respect to super water absorbent polymer product) into the grafted co-polymer for obtaining the super absorbent polymer containing Zn-EDTA;
g) drying the super absorbent polymer containing Zn-EDTA obtained in the step f) under a tray dryer using up and down flow of hot air at a temperature range of 140°C -170°C for 30-60 minutes; and
h) grinding the dried the super absorbent polymer containing Zn-EDTA obtained in the step f) so as to have a particle size of 800-1200 microns.

[091] The water absorbance was recorded to be 130-170 g/g. The pH and moisture content was found to be 6.8-7.3 and 1.2-2.4% respectively.

Example 6: Incorporation of Zn-EDTA and sulphur into super water absorbent polymer product:
[092] 20-30 g Modified starch, 30-50 g acrylic acid monomer (40%-80% neutralized), neutralizing agent (preferably potassium hydroxide), acrylamidoalkanesulfonic acid (preferably 2-Acrylamido-2-methylpropane sulfonic acid), a cross-linker (0.25wt % of the super water absorbent polymer preferably methylene bis-acrylamide (MBA)) and water are mixed in a reaction kettle, followed by addition of polymerization initiator (preferably Potassium persulphate) at a temperature of about 65°C to initiate the polymerization reaction. Once the polymerization is complete, super water absorbent polymer product comprising the grafted co-polymer with sulfur containing compound is obtained. The grafted co-polymer with sulfur containing compound thus obtained is mixed with Zn-EDTA solution (0.08wt% with respect to super water absorbent polymer product) to obtain the super water absorbent polymer product. The super water absorbent polymer product cooled to room temperature and cut into small pieces for drying in a hot air oven. The super water absorbent polymer product containing Zn-EDTA and sulfur is then dried in a hot air oven at 65-70 °C, overnight. The super water absorbent polymer product comprising Zn-EDTA and sulfur containing compound is grinded to particle size of 600-1200 microns. The water absorbance was recorded and found to be 160-190 g/g. The pH and moisture content was found to be 6.1-7.6 and 2.1-2.5% respectively.

Example 7: Incorporation of Zn-EDTA and Hydroxyapatite into super water absorbent polymer product:
[093] 20-30 g starch, 30-50 g acrylic acid monomer, sodium or potassium hydroxide (40-90% neutralization), 0.1-1.0 wt% of a suitable crosslinker like methylene bis- acrylamide (MBA) or Trimethylolpropane triacrylate (TMPTA), 2-8 wt% of hydroxyapatite and Zn-EDTA solution (0.02wt% with respect to super water absorbent polymer product) were taken. All the raw materials were mixed in a reaction kettle first having 20-50% solid content in water medium, followed by addition of persulphate-based initiator (0.1-1.0 wt %) at a temperature range of 60-70°C to initiate the polymerization reaction. After completion of the polymerization reaction the super water absorbent polymer product containing Zn-EDTA and Hydroxyapatite was obtained. The product thus obtained was cooled to room temperature and cut into small pieces for drying in a hot air oven65-70°C, overnight. After drying the super water absorbent polymer product containing Zn-EDTA and Hydroxyapatite was grinded to have particle size of 600-1200 microns. The water absorbance was recorded and was found to be 120-160 g/g. The pH and moisture content was found to be 7.3-7.6 and 1.9-2.6% respectively.

Example 8: Incorporation of Zn-EDTA, sulphur and Hydroxyapatite into super water absorbent polymer product:
[094] 20-30 g Modified starch, 30-50 g acrylic acid monomer, neutralizing agent (preferably potassium hydroxide) (40%-90% neutralization), acrylamidoalkanesulfonic acid (preferably 2-Acrylamido-2-methylpropane sulfonic acid), 0.1-1.0 wt% a cross-linker (preferably methylene bis- acrylamide (MBA)) and water are mixed in a reaction kettle, followed by addition of polymerization initiator (preferably Potassium persulphate) at a temperature of about 60°C to initiate the polymerization reaction. Once the polymerization is complete, grafted co-polymer product with sulfur containing compound is obtained. After obtaining the grafted co-polymer product with sulfur containing product, the grafted co-polymer product is mixed with the Zn-EDTA nanoparticle solution (0.08wt% with respect to super water absorbent polymer product) and 2-8 wt% of hydroxyapatite to obtain super water absorbent polymer containing Zn-EDTA, hydroxyapatite and sulfur. The super water absorbent polymer containing Zn-EDTA and hydroxyapatite product obtained is then cooled to room temperature and cut into small pieces and dried in a hot air oven at 65-70 °C, overnight. The dried super water absorbent polymer product containing Zn-EDTA, Hydroxyapatite and sulfur is grinded to particle size of 600-1200 microns. The water absorbance was recorded to be 130-175 g/g. The pH and moisture content was found to be 6.7-7.5 and 2.3-2.7% respectively.

Example 9: Preparation of modified Hydroxyapatite
[095] Modified hydroxyapatite containing Ca, N, P is prepared by a wet chemical method. In particular, urea and hydroxyapetatite in their weight ratio of 1:1-5:1 was used with a solid content of 40%. Firstly, urea and calcium hydroxide is dispersed in water under ambient condition. Then 0.6 moles of phosphoric acid (with respect to calcium hydroxide) is added drop wise to the mixture under ambient condition. The nanosized water dispersed hydroxyapatite-urea nanosized fertilizer was achieved after 2h stirring. The particle size was measured by DLS and was found to be 7.301.

Example 10: Incorporation of Zn-EDTA, sulphur and modified Hydroxyapatite into super water absorbent polymer product:
[096] 20-30g Modified starch, 30-50g acrylic acid monomer, neutralizing agent (preferably potassium hydroxide) (40%-90% neutralization), acrylamidoalkanesulfonic acid (preferably 2-Acrylamido-2-methylpropane sulfonic acid), 0.1-1.0 wt% a cross-linker (preferably methylene bis-acrylamide (MBA)) and water are mixed in a reaction kettle, followed by addition of polymerization initiator (preferably Potassium persulphate) at a temperature of about 50°C to initiate the polymerization reaction. Once the polymerization is complete, grafted co-polymer containing sulfur compound is obtained. The grafted co-polymer containing sulfur is soaked overnight with Zn-EDTA solution (0.025wt% with respect to super water absorbent polymer product) and 2-8 wt% of modified hydroxyapatite (comprising urea) to obtain super water absorbent polymer containing Zn-EDTA, modified Hydroxyapatite and sulfur. The super water absorbent polymer product is then cooled to room temperature and cut into small pieces for drying in a tray dryer using up flow and down flow hot air at 65-70°C, overnight. The dried super water absorbent polymer product comprising Zn-EDTA, modified Hydroxyapatite and sulfur containing compound is grinded to particle size of 600-1200 microns. The water absorbance was recorded to be 140-180 g/g. The pH and moisture content was found to be 6.7-7.5 and 2.3-2.7% respectively.

Example 11: Incorporation of Zn-EDTA and modified Hydroxyapatite into super water absorbent polymer product:
[097] 20-30g Modified starch, 30-50g acrylic acid monomer, neutralizing agent (preferably potassium hydroxide) (40%-90% neutralization), Zn-EDTA solution (0.025wt% with respect to super water absorbent polymer product), 2-8 wt% of modified hydroxyapatite (comprising urea), 0.1-1.0 wt% of a cross-linker (preferably methylene bis- acrylamide (MBA)) and water are mixed in a reaction kettle, followed by addition of polymerization initiator (preferably Potassium persulphate) at a temperature of about 50°C to initiate the polymerization reaction. Once the polymerization is complete, super water absorbent polymer product comprising Zn-EDTA (0.025wt% with respect to super water absorbent polymer product) and 2-8 wt% of modified Hydroxyapatite is obtained. The super water absorbent polymer product thus obtained is cooled to room temperature and cut into small pieces for drying in a hot air oven at 65-70 °C, overnight. The dried super water absorbent polymer product comprising Zn-EDTA and modified Hydroxyapatite is grinded to particle size of 600-1200 microns. The water absorbance was recorded to be 130-160 g/g. The pH and moisture content was found to be 7.1-7.7 and 2.2-2.9% respectively.

Advantages of the present invention
[098] Some of the advantages of the invention include:
• the plant nutrient carrying super water absorbent polymer product comprises the Zn-EDTA make a complex with heavy metals, Zn-EDTA helps to reduce their toxicity, making them less harmful to plants. The complex not only detoxifies the soil but also prevents heavy metals from entering the food chain, thus promoting safer agricultural practices.
• the plant nutrient carrying super water absorbent polymer product having better response in terms of a germination, a plant height, plant branches, increased tillering and plant stand, dark green colour foliage, early pod formation, higher number of pods, ear head length is more and having higher number of seeds than a chemical fertilizer;
• the plant nutrient carrying super water absorbent polymer product comprising ZN-EDTA easily applies the Zn to the soil and the plant.
• incorporation of Zn-EDTA in the plant nutrient carrying super water absorbent polymer product does not lead to substantially reduction in water absorption capacity of the super water absorbent polymer product;
• incorporation of Zn-EDTA into the super water absorbent polymer product does not hinder in incorporation of other elements such as sulphur, hydroxyapatite, a combination of sulphur and hydroxyapatite, modified hydroxyapatite, a combination of sulphur and modified hydroxyapatite;
• the plant nutrient carrying super water absorbent polymer product having Zn-EDTA and Sulphur has modified texture as compared to a super water absorbent polymer product which is devoid of ZN-EDTA and sulfur containing compound;
• the plant nutrient carrying super water absorbent polymer product having Zn-EDTA and Sulphur has has a higher porosity as compared to a super water absorbent polymer product which is devoid of Zn-EDTA and sulfur containing compound. Due to the higher porosity, a variety of advantages are derived;
• the plant nutrient carrying super water absorbent polymer product comprising Zn-EDTA and the sulfur containing compound and facilitates in delivery of Zn-EDTA as well as sulphur, both of which essential for the plant. Thus, the plant nutrient carrying super water absorbent polymer product comprising Zn-EDTA and the sulfur containing compound has better efficacy as compared to the super water absorbent polymer product devoid of Zn-EDTA and the sulfur containing compound;
• the plant nutrient carrying super water absorbent polymer product comprising Zn-EDTA optionally along with one of more of sulphur, hydroxyapatite, and modified hydroxyapatite have better response in terms of a germination, a plant height, plant branches, increased tillering and plant stand, dark green colour foliage, early pod formation, higher number of pods, ear head length is more and having higher number of seeds than a chemical fertilizer;
• the water absorbent property of the plant nutrient carrying super water absorbent polymer product comprising Zn-EDTA optionally along with one of more of sulphur, hydroxyapatite, and modified hydroxyapatite is equal to or greater than the water absorbent property of the super water absorbent polymer product devoid of Zn-EDTA and the optional element (which may be sulphur, hydroxyapatite, and modified hydroxyapatite);
• an amount of time for bio-degradation of the plant nutrient carrying super water absorbent polymer product comprising Zn-EDTA optionally along with one of more of sulphur, hydroxyapatite, and modified hydroxyapatite is less than or equal to an amount of time for bio-degradation of the super water absorbent polymer product devoid of Zn-EDTA and the optional element (which may be sulphur, hydroxyapatite, and modified hydroxyapatite).
• the plant nutrient carrying super water absorbent polymer product comprising is easy to dry.
• at least one of an amount of hot air used for drying the plant nutrient carrying super water absorbent polymer product or a temperature of hot air used to dry the plant nutrient carrying super water absorbent polymer product temperature or a time period needed to dry the plant nutrient carrying super water absorbent polymer product is reduced.

[099] While specific language has been used to describe the disclosure, any limitations arising on account of the same are not intended. As would be apparent to a person in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein.
,CLAIMS:WE CLAIM:

1. A plant nutrient carrying super water absorbent polymer product comprising a grafted co-polymer comprising polyglucosyl polymer chain linked to at least one acrylic acid or acrylate polymer chain and a Zinc-ethylenediaminetetraacetic acid (Zn-EDTA) complex loaded on the grafted co-polymer.

2. The plant nutrient carrying super water absorbent polymer product as claimed in claim 1, wherein the Zn-EDTA complex is present in an amount in the range of about 0.01 to about 0.1% by weight of the plant nutrient carrying super water absorbent polymer product.

3. The plant nutrient carrying super water absorbent polymer product as claimed in claim 1, wherein the polyglucosyl polymer chain being present in an amount in the range of about 18% to about 90% by weigh, the cross-linking agent being present in an amount of about 0.1 to about 10 % by weight and the acrylic acid or acrylate polymer chain being present in an amount of about 50 to about 90 % by weight.

4. The plant nutrient carrying super water absorbent polymer product as claimed in claim 1, wherein the polyglucosyl polymer chain is selected such that an aqueous solution containing 50% w/v of the polyglucosyl polymer chain has viscosity in the range of 5000-50000 cps at a room temperature.

5. The plant nutrient carrying super water absorbent polymer product as claimed in claim 1, wherein a hydroxyapatite being present in an amount of about 1 to 10% by weight of plant nutrient carrying super water absorbent polymer, the hydroxyapatite comprises un-modified hydroxyapatite having a size in the range of 1 to 30 nm and a modified hydroxyapatite having a size in the range of 1 to 60 nm.

6. The plant nutrient carrying super water absorbent polymer as claimed in claim 5, wherein the modified starch is selected from a group comprising an enzymatically modified starch, dextrinised starch, an acid treated starch, an alkali treated starch, a bleached starch, an oxidized starch, mono-starch phosphate, di-starch phosphate, phosphated di-starch phosphate, acetylated distarch phosphate, starch acetate, hydroxypropyl starch, hydroxypropyl distarch phosphate, starch sodium octenyl succinate, acetylated oxidized starch, and starch aluminum octenyl succinate.

7. The plant nutrient carrying super water absorbent polymer product as claimed in claim 1, wherein the cross-linkers include methylene bis-acrylamide (MBA) or Trimethylolpropane triacrylate (TMPTA) or Trimethylolpropane ethoxylate triacrylate (EO-TMPTA) or polyethylene glycol diacrylate (PEGDA).

8. The plant nutrient carrying super water absorbent polymer product as claimed in claim 1, the acrylic acid or acrylate polymer chain comprises acrylic acid monomer neutralized to an extent of 40 to 90% by the neutralizing agent.

9. A process for preparing a super water absorbent polymer product, said process comprising mixing at least one acrylic acid or acrylate monomer, a polyglucosyl polymer, a cross-linking agent, and a Zn-EDTA complex under a polymerizing condition to obtain the super water absorbent polymer product.