CONTROLLED-RELEASE FERTILIZER COATED WITH A WAX LAYER AND A POLYMER LAYER AND METHOD OF PREPARING THE SAME

• US 20100139348A1
• Filed: 02/15/2010
• Published: 06/10/2010
• Est. Priority Date: 08/15/2007
• Status: Abandoned Application

• Current Assignee: Bing Yu, Hongkun Chen, Lianbu Wan, Li Li, Li Yang
• Original Assignee: Bing Yu, Hongkun Chen, Lianbu Wan, Li Li, Li Yang
• Inventors: LI, Li, YANG, Li, WAN, Lianbu, CHEN, Hongkun, YU, Bing
• Application Number:
  US12/705,646
• Publication Number:
  US 20100139348A1
• Time in Patent Office: Days
• US Class Current: 71/23
• CPC Class Codes: C05G 5/37 layered or coated with a polymer
• CPC Class Codes: C05G 5/38 layered or coated with wax or resins
• CPC Class Codes: C08F 2/24 with the aid of emulsifying agents
• CPC Class Codes: C08F 212/08 Styrene
• CPC Class Codes: C08F 220/06 Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
• CPC Class Codes: C08F 220/1802 C2-(meth)acrylate, e.g. ethyl (meth)acrylate
• CPC Class Codes: C08F 220/1804 C4-(meth)acrylate, e.g. butyl (meth)acrylate, isobutyl (meth)acrylate or tert-butyl (meth)acrylate
• CPC Class Codes: C08F 220/1818 C13or longer chain (meth)acrylate, e.g. stearyl (meth)acrylate
• CPC Class Codes: C09D 125/14 with unsaturated esters

Abstract

A controlled-release fertilizer having a fertilizer core and a coating applied thereon, the coating comprising a wax film layer and a polymer film layer. A method of preparation of the controlled-release fertilizer.

Claims

1. A controlled-release fertilizer comprising a fertilizer core and a coating applied thereon, wherein said coating comprises a wax film layer and as a coating agent a polymer film layer comprising an aqueous polymer emulsion and a biodegradable natural macromolecule.

2. The controlled-release fertilizer of claim 1, wherein said wax is a liquid wax or a solid wax having a melting point of less than 60°

C.

3. The controlled-release fertilizer of claim 1, wherein a weight of said wax film is between 0.3 and 5% of the total weight of said fertilizer.

4. The controlled-release fertilizer of claim 1, wherein the weight of said polymer film is between 5 and 20% of the total weight of said fertilizer.

5. The controlled-release fertilizer of claim 1, wherein said aqueous polymer emulsion is, at presence of an initiator, an emulsifier, and a co-emulsifier, polymerized by a hard monomer, a soft monomer, and a functional monomer of an unsaturated acid capable of free radical polymerization, a weight ratio of said hard monomer to said soft monomer being between 2:

1 and 1;

2, and said functional monomer being between 0.2 and 15 wt. % of the total weight of said monomers.

6. The controlled-release fertilizer of claim 5, wherein said hard monomer is a styrene monomer, methyl methacrylate, or a mixture thereof, said soft monomer is an acrylate represented by formula of CH₂═

CH—

C(O)OR, or a mixture thereof, wherein R represents a straight-chain or a branched-chain C_1-18alkyl, and said functional monomer is acrylic acid, methacrylic acid, butene diacid, or a mixture thereof.

7. The controlled-release fertilizer of claim 5, wherein said emulsifier is an anionic emulsifier or a mixture of an anionic emulsifier and a non-ionic emulsifier.

8. The controlled-release fertilizer of claim 7, wherein said anionic emulsifier is RCOONa, ROSO₃Na, RSO₃Na, RC₆H₄SO₃Na, wherein R represents C_12-18alkyl, sodium alkyl diphenyl ether disulphonate, disproportionated rosin, sodium alkyl naphthalene sulfonate, or a mixture thereof, said non-ionic emulsifier is polyoxyethylene sorbitan fatty acid ester, alkylphenol polyoxyethylene ether, alkyl polyoxyethylene ether, or a mixture thereof, and said co-emulsifier is a long-chain fatty alcohol having eight or more carbon atoms.

9. The controlled-release fertilizer of claim 7, wherein based on the total weight of said monomers, said anionic emulsifier accounts for between 0.3 and 5.0 wt. %, said non-ionic emulsifier accounts for between 0 and 5.0 wt. %, and said co-emulsifier accounts for between 0 and 1.0 wt. %.

10. The controlled-release fertilizer of claim 5, wherein said polymerization is achieved by a semi-continuous emulsion polymerization process, a seed emulsion polymerization process, or a pre-emulsion polymerization process.

11. The controlled-release fertilizer of claim 5, wherein said initiator is added in batches.

12. The controlled-release fertilizer of claim 5, wherein the temperature for said emulsion polymerization is between 60 and 95°

C., and the time period for said emulsion polymerization is between 3 and 12 hrs.

13. The controlled-release fertilizer of claim 5, wherein the solid content of said aqueous polymer emulsion is between 20 and 70%.

14. The controlled-release fertilizer of claim 5, wherein at dry state, the particle size of said polymer is between 30 and 2000 nm.

15. The controlled-release fertilizer of claim 5, wherein the glass transition temperature of said polymer is between 5 and 65°

C.

16. The controlled-release fertilizer of claim 1, wherein said biodegradable natural macromolecule is corn starch, potato starch, wheat starch, sweet potato starch, flour, cereal flour, or a mixture thereof.

17. The controlled-release fertilizer of claim 1, wherein said coating agent is prepared by dispersing said biodegradable natural macromolecule in water to form a paste, and for mixing with said aqueous polymer emulsion.

18. The controlled-release fertilizer of claim 1, wherein based on the dry weight of said coating agent, said aqueous polymer emulsion accounts for between 80 and 99 wt. %, and said biodegradable natural macromolecule accounts for between 1 and 20 wt. %.

19. The controlled-release fertilizer of claim 1, wherein said polymer film layer was coated with an inorganic layer comprising inorganic powder.

20. The controlled-release fertilizer of claim 19, wherein the weight of said inorganic powder is between 0.3 and 10% of the total weight of said fertilizer.

21. A method of preparing a controlled-release fertilizer, comprising in a fluidized bed, (a) providing a fertilizer particle, (b) coating said fertilizer particle with a wax film layer, and (c) coating said wax film layer with a polymer film layer as a coating agent comprising an aqueous polymer emulsion and a biodegradable natural macromolecule.

22. The method of claim 21, wherein the temperature in said fluidized bed is between 30 and 80°

C., the spraying temperature of said wax film layer is between 0 and 80°

C., and the spraying temperature of said coating agent is between 30 and 60°

C.

23. The method of claim 21, further comprising coating said polymer film layer with an inorganic layer comprising inorganic powder.

24. The method of claim 23, wherein a coating temperature of said inorganic powder is between 30 and 80°

C.