Chemistry: fertilizers – Processes and products – Forms or conditioning
Reexamination Certificate
1999-05-19
2001-05-15
Langel, Wayne (Department: 1754)
Chemistry: fertilizers
Processes and products
Forms or conditioning
C071S028000, C071S029000, C071S030000, C071S033000, C071S058000, C071S063000, C071S064020, C071S064110
Reexamination Certificate
active
06231633
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a controlled-release (also referred to as slow-release, sometimes) granular coated fertilizer, and a method for producing the same. More particularly, the present invention relates to a controlled-release granular coated fertilizer, which is coated with a thermosetting resin such as urethane resin, epoxy resin or the like, and a method for producing the same.
2. Description of the Related Art
A so-called slow-release granular fertilizer wherein a dissolution rate of the fertilizer is controlled by coating or encapsulizing a granular fertilizer with a resin, sulfur, etc. has been used for years. For example, Japanese Patent Kokoku Publication Nos. 40-28927, 44-28457, 37-15382 and 42-13681 disclose various coating materials and coating methods.
U.S. Pat. No. 3,264,089 discloses a coated fertilizer wherein a coating material is a urethane resin made of a reaction product of a polyisocyanate compound and a polyol compound, while U.S. Pat. No. 3,264,088 discloses an epoxy resin coating material. With respect to a method for producing a coated fertilizer, comprising using a urethane resin as a coating material, Japanese Patent Kohyo Publication No. 1-500661 discloses a technique characterized in that an excessive amount of an isocyanate compound is reacted with a urea fertilizer on the surface to form a base coat and a polyol compound is reacted with excess isocyanate groups thereon. Japanese Patent Kohyo Publication No. 7-500560 discloses a technique characterized in that a mixed resin of a polyisocyanate compound and a polyol compound is coated to form each layer having a thickness of 10 to 30 &mgr;m which is then cured by treating with an amine mist.
However, these techniques have industrially disadvantageous problems because the object of realizing less coating defects and controlled dissolution of the fertilizer is not sufficiently satisfied or a complicated apparatus and complicated steps are required in the production.
In these methods, a dissolution rate of the fertilizer to the external environment is decided by the property of the resin or the kind of the fertilizer. Therefore, in order to retard the dissolution rate, it is effective to increase a coating film thickness of the resin. However, since a proportion of an effective fertilizer per unit weight of the coated fertilizer is decreased, it is necessary to apply a large amount of a coated fertilizer to soil. A large amount of the resin is required and, therefore, there arise a problem about cost and a problem that the productivity is lowered by prolongation of the time required to produce the coated fertilizer.
On the other hand, a technique of coating a fertilizer with a hydrophobic compound such as wax has been known, and Japanese Patent Kokoku Publication No. 6-2632 and Japanese Patent Kokai (laid-open) Publication No. 52-93561 disclose a method of wax coating to prevent hygroscopic fertilizer products from adhering each other.
In the coated fertilizer, which is coated with a resin, a problem of adhering of resins does not occur. Therefore, it is not necessary to add a hydrophobic compound.
An object of the present invention is to provide a granular coated fertilizer wherein a dissolution rate is further retarded than a slow-release granular coated fertilizer, which is coated with a thermosetting resin, and a method for producing the same.
SUMMARY OF THE INVENTION
The present invention is as described below.
[1] A granular coated fertilizer coated with a thermosetting resin, characterized in that a dissolution rate of the fertilizer is retarded by containing a hydrophobic compound in at least one of a coating portion and a fertilizer portion thereof.
[2] The granular coated fertilizer according to the item [1], wherein an amount of the hydrophobic compound is from 0.1 to 100 parts by weight based on 100 parts by weight of the thermosetting resin.
[3] The granular coated fertilizer according to the item [1] or [2], wherein the hydrophobic compound is selected from the group consisting of wax, fatty acid, fatty acid ester, higher alcohol, silicone and mixtures thereof.
[4] The granular coated fertilizer according to the item [1] or [2], wherein the thermosetting resin is an epoxy resin or a urethane resin.
[5] The granular coated fertilizer according to the item [4], wherein the urethane resin contains a polyisocyanate compound, a polyol compound and a curing catalyst as essential components therein.
[6] A method for producing a granular coated fertilizer comprising any one of the steps below:
(A) coating a granular fertilizer, to which a hydrophobic compound is previously added, with a thermosetting resin;
(B) coating a granular fertilizer with a thermosetting resin, to which a hydrophobic compound is previously added;
(C) coating a granular fertilizer with a thermosetting resin, with an adding of a hydrophobic compound intermittently or continuously, to a mixture of the granular fertilizer and the thermosetting resin, either during or after the granular fertilizer is coated with the thermosetting resin; or
(D) using two or more steps of the above steps A to C in combination.
[7] The method for producing a granular coated fertilizer according to the item [6] comprising the steps of:
(1) placing the granular fertilizer into a rolling state;
(2) adding a liquid uncured thermosetting resin to the granular fertilizer in the rolling state in an amount that is enough to secure a layer thickness of 1 to 10 &mgr;m;
(3) coating surfaces of fertilizer granules of the granular fertilizer with the uncured thermosetting resin while maintaining the rolling state of the granular fertilizer;
(4) thermosetting the uncured thermosetting resin while maintaining the rolling state of the granular fertilizer; and
(5) repeating the above steps (1) to (4) one or more times, in this order.
[8] The method according to item [6] or [7], wherein an amount of the hydrophobic compound is from 0.1 to 100 parts by weight based on 100 parts by weight of the thermosetting resin.
[9] The method according to the item [6] or [7], wherein the hydrophobic compound is selected from the group consisting of wax, paraffin, fatty acid, fatty acid ester, higher alcohol, silicone and mixtures thereof.
[10] The method according to the item [6] or [7], wherein the thermosetting resin is an epoxy resin or a urethane resin.
[11] The method according to the item [10], wherein the urethane resin contains a polyisocyanate compound, a polyol compound and a curing catalyst as essential components.
[12] The method according to the item [6] or [7], wherein the thermosetting resin has a gelation time of not more than 5 minutes at a coating temperature.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail hereinafter.
As the hydrophobic compound in the present invention, a so-called wax is used. Specific examples thereof include animal wax such as-beeswax, etc.; vegetable wax such as candelilla wax, carnauba wax, wood wax, ouricury wax, douglas fir bark wax, lice bran wax, jojoba wax, bayberry wax, etc.; mineral wax such as montan wax, peat wax, ozokerite-ceresin wax, etc.; petroleum wax such as paraffin wax, microcrystalline wax, semicrystalline wax, etc.; polymer wax such as polyethylene wax, copolymer wax obtained by polymerizing at least two monomeric units such as ethylene, propylene, butadiene, acrylic acid, etc.; and synthetic wax such as Fischer-Tropsch wax, chemically-modified hydrocarbon wax, substituted amide wax, etc.
The petroleum wax is not limited to a solid and includes, for example, hydrocarbons such as alkanes, paraffins, alkenes, olefins, alkynes, acetylenes, cycloalkanes, cycloalkenes, cycloalkynes, etc.; and aromatic hydrocarbons.
Examples of the fatty acid in
Hirano Yasuhiro
Nakamura Hiroshi
Yamaguchi Yutaka
Langel Wayne
Sughrue Mion Zinn Macpeak & Seas, PLLC
Sumitomo Chemical Company Limited
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