WO2025127105A1 - Coating composition for agricultural use, and coated seed - Google Patents

Abstract

The present invention addresses the problem of providing a coating composition for agricultural use, which has biodegradability and generates less amount of dust.　Disclosed is a coating composition for agricultural use, which contains a vinyl alcohol-based polymer (A) in which the retention time RT of a peak top is 22 minutes or more as measured by reversed-phase partition gradient high performance liquid chromatography using a water-ethanol eluent.

Description

Agricultural coating composition and coated seeds

This patent application claims priority under the Paris Convention to Japanese Patent Application No. 2023-209809 (filing date: December 13, 2023), the entire contents of which are incorporated herein by reference.
The present invention relates to an agricultural coating composition containing a vinyl alcohol polymer and a coated seed.

Agricultural coating compositions used to cover agricultural materials, such as seed coating compositions, are widely used to coat seeds to increase the probability that the seeds will grow into crops. In order to prevent the seeds from being invaded by saprophytic fungi or insects before germination, pesticides are often added to such seed coating compositions. However, in the past, seed coating compositions containing pesticides coated on seeds often peel off and spread into the surrounding environment, causing adverse effects on workers and organisms in the environment. In order to reduce the peeling of pesticides from seeds, binders mainly composed of polyacrylic acid esters that have high adhesion to the seed surface (Patent Document 1) and glossy seed coating materials containing glittering materials, talc, polyvinyl alcohol, ethylene-vinyl acetate copolymers, and aqueous media (Patent Document 2) are known. However, these documents do not disclose agricultural coating compositions such as seed coating compositions that are biodegradable and less likely to peel off from seeds.

International Publication No. WO 2013/166020 International Publication No. 2019/176272

The present invention aims to provide an agricultural coating composition that is biodegradable and generates little dust, and a coated seed that is coated with the agricultural coating composition.

The above object can be achieved by an agricultural coating composition containing a vinyl alcohol polymer (A) having a peak top retention time RT of 22 minutes or more as measured by reversed-phase partition gradient high performance liquid chromatography using a water-ethanol eluent. The present invention includes the following preferred embodiments.
[1] An agricultural coating composition comprising a vinyl alcohol polymer (A) having a peak top retention time (RT) of 22 minutes or longer as measured by reversed-phase gradient high-performance liquid chromatography using a water-ethanol eluent.
[2] The agricultural coating composition according to [1], wherein the saponification degree of the vinyl alcohol polymer is less than 70.0 mol%.
[3] The agricultural coating composition according to [2], wherein the vinyl alcohol polymer (A) is an unmodified vinyl alcohol polymer.
[4] The agricultural coating composition according to [1], further comprising inorganic fine particles.
[5] The agricultural coating composition according to [4], wherein the inorganic fine particles are at least one selected from the group consisting of talc, mica, diatomaceous earth, limestone, gypsum, bentonite, vermiculite, zeolite, silica sand and barium sulfate.
[6] The agricultural coating composition according to [5], wherein the inorganic fine particles contain talc.
[7] The agricultural coating composition according to [4], wherein a mass ratio of the inorganic fine particles to the vinyl alcohol polymer is 0.5:1.0 to 5.0:1.0.
[8] The agricultural coating composition according to any one of [1] to [7], wherein the agricultural coating composition is a seed coating composition.
[9] A coated seed, in which at least a part of the surface of the seed is coated with the agricultural coating composition according to any one of [1] to [7].
[10] The coated seed according to [9], wherein the seed is at least one type selected from the group consisting of corn, wheat and soybean.

The agricultural coating composition of the present invention is excellent in that it is biodegradable and generates little dust.

In this specification, a numerical range described using "~" means that the numerical values described before and after "~" are included as the lower and upper limits. In this specification, the upper and lower limits of a numerical range (content, physical properties, etc.) can be combined as appropriate.

<Agricultural Coating Composition>
The agricultural coating composition of the present invention is an agricultural coating composition containing a vinyl alcohol polymer (A) having a peak top retention time RT of 22 minutes or more as measured by reversed-phase partition gradient high performance liquid chromatography using a water-ethanol eluent. Hereinafter, the "vinyl alcohol polymer" may be referred to as "PVA", and the vinyl alcohol polymer (A) satisfying the above-mentioned specific requirements may be referred to as PVA (A).

The agricultural coating composition of the present invention is a composition used for coating agricultural materials. One preferred embodiment of the agricultural coating composition of the present invention is a coating composition for seeds. Another preferred embodiment of the present invention is an agricultural coating composition used to coat agricultural materials other than seeds, and agricultural materials other than seeds include fertilizer, soil, sand, stones, etc., and it is particularly preferred that the agricultural coating composition is a fertilizer coating composition that coats fertilizer.

The PVA (A) contained in the agricultural coating composition of the present invention is a polymer containing vinyl alcohol units as structural units. The lower limit of the ratio of vinyl alcohol units to all structural units in PVA (A) is, for example, preferably 10 mol%, more preferably 20 mol%, even more preferably 30 mol%, and even more preferably 40 mol%. On the other hand, the upper limit of the ratio of vinyl alcohol units is, for example, preferably 90 mol%, more preferably 80 mol%, and even more preferably 60 mol%. In other words, the suitable ratio of vinyl alcohol units to all structural units in PVA (A) is, for example, 10 to 90 mol%, and each of the above-mentioned preferable numerical ranges is suitable. PVA (A) may be obtained, for example, by polymerizing a vinyl ester monomer and saponifying the obtained vinyl ester polymer, and PVA (A) may contain, for example, vinyl ester units in addition to vinyl alcohol units.

PVA(A) has a peak top retention time (RT) of 22 minutes or more when measured by reversed-phase partition gradient high-performance liquid chromatography using a water-ethanol eluent. Here, "peak top" refers to the point where the detection intensity in the chromatogram obtained by chromatography measurement is the maximum and is a local maximum value, and means the peak top derived from PVA(A). Such PVA is highly hydrophobic and has excellent adhesive strength between PVA and the seed surface. This is thought to be because the highly hydrophobic PVA is adsorbed to the seed surface, which improves the adhesive strength between PVA and the seed surface, compared to the hydrophobic seed surface. PVA(A) preferably has a retention time RT of more than 22 minutes. Also, PVA(A) preferably has a retention time RT of 25 minutes or less. In other words, the preferred range of retention time RT is, for example, 22 to 25 minutes, and the above-mentioned preferred numerical range is suitable. PVA(A) with 22 minutes < RT < 25 minutes is more preferred. The retention time RT of PVA (A) can be adjusted by adjusting the introduction of modifying groups, the degree of saponification, and the viscosity average degree of polymerization.

The retention time RT of the PVA (A) can be measured under the following measurement conditions.
Column: Shimpack G-ODS (4) (Shimadzu Corporation, octadecyl-modified spherical fully porous silica gel, inner diameter 4 mm × length 10 mm, particle size 5 μm)
Column temperature: 45°C
Eluent: ion-exchanged water (X), ethanol (purity 99.5%) (Y)
Eluent composition at each measurement time (concentration is by volume):
0 to 5 minutes: (Y) Concentration 5% constant 5 to 25 minutes: (Y) Concentration 5 to 100%
25-40 minutes: (Y) concentration 100% constant 40-41 minutes: (Y) concentration 100-5%
41-55 minutes: (Y) Concentration 5% constant mobile phase flow rate: 0.4 mL/min
Sample concentration: 5 mg/mL
Detector: ELSD-LTII (Shimadzu Corporation, drift tube temperature 40°C, gain 6 (=32 times), _N2 gas spray pressure primary 0.4 MPa, secondary 0.35 MPa, data acquisition interval: 1000 ms, filter: 1 sec.)
Injection volume: 5μL
Length from injection to column inlet: 900 mm
Length from column outlet to nebulizer of ELSD-LTII detector: 1375 mm
Pipe diameter: 0.3 mm ID

The lower limit of the saponification degree of PVA (A) is preferably 20 mol%, more preferably 30 mol%, even more preferably 40 mol%, and even more preferably 45 mol%. The saponification degree of PVA (A) is preferably less than 70 mol%, and in one embodiment, the upper limit of the saponification degree of PVA (A) is more preferably 69.9 mol%, even more preferably 65 mol%, and even more preferably 55 mol%. That is, the preferred range of the saponification degree of PVA (A) is, for example, 20 mol% to less than 70 mol%, and each of the above-mentioned preferred ranges of values is suitable. When the saponification degree of PVA (A) is in the above range, adhesion (coverability) to the seed surface and biodegradability are superior. The saponification degree of PVA (A) is measured by the method described in JIS K6726:1994.

The lower limit of the viscosity average degree of polymerization of PVA (A) is preferably 100, more preferably 150, and even more preferably 200. The upper limit of the viscosity average degree of polymerization of PVA is preferably 3500, more preferably 2000, even more preferably 1500, even more preferably 1000, particularly preferably 500, and in some cases even more particularly preferably 300. That is, a suitable range of the viscosity average degree of polymerization of PVA (A) is, for example, 100 to 3500, and each of the above-mentioned preferred ranges of values is suitable. When the viscosity average degree of polymerization of PVA (A) is in the above range, adhesion (covering ability) to the seed surface is superior. The viscosity average degree of polymerization of PVA (A) is measured in accordance with JIS K6726:1994.

PVA (A) can be produced, for example, by saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester monomer. Examples of vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl versatate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl palmitate, vinyl stearate, and vinyl oleate. Among these, vinyl acetate is preferred from the viewpoints of availability and economy. As the vinyl ester monomer, only one type may be used, or two or more types may be used in combination.

The PVA (A) may be a modified PVA into which units or functional groups other than units derived from vinyl ester monomers have been introduced using techniques such as copolymerization, acetalization, and esterification.

When PVA (A) is a copolymer-modified PVA, the copolymer-modified PVA can be obtained, for example, by saponifying a vinyl ester copolymer obtained by copolymerizing a vinyl ester monomer with a monomer other than a vinyl ester monomer. The monomer other than the vinyl ester monomer that is copolymerized with the vinyl ester monomer may be used as long as it is copolymerizable with the vinyl ester monomer within a range that does not impair the effects of the present invention. Examples of such monomers include α-olefins such as ethylene, propylene, 1-butene, isobutene, pentene, 1-hexene, 1-octene, 1-dodecene, 1-hexadecene, and 1-octadecene; (meth)acrylic acid; (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, stearyl (meth)acrylate, and octadecyl (meth)acrylate; and acrylamide derivatives such as N-methylacrylamide and N-ethylacrylamide. Conductors; methacrylamide derivatives such as N-methyl methacrylamide and N-ethyl methacrylamide; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, lauryl vinyl ether, and vinyl ether stearate; allyl acetate; allyl ethers such as propyl allyl ether, butyl allyl ether, and hexyl allyl ether; monomers having an oxyalkylene group; isopropenyl acetate; monomers having a silyl group such as vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, vinyldimethylethoxysilane, 3-(meth)acrylamidopropyltrimethoxysilane, and 3-(meth)acrylamidopropyltriethoxysilane. These may be used alone or in combination of two or more.

When PVA (A) is a modified PVA in which a modifying group has been introduced by acetalization, the modifying agent used for the introduction of the modifying group by acetalization is not particularly limited as long as it does not impair the effects of the present invention, and examples thereof include linear, branched, cyclically saturated, cyclically unsaturated, or aromatic aldehydes and aldoses having 1 to 19 carbon atoms. Specific examples thereof include formaldehyde, acetaldehyde, propionyl aldehyde, n-butyl aldehyde, isobutyl aldehyde, tert-butyl aldehyde, benzaldehyde, cyclohexyl aldehyde, pentanal, hexanal, heptanal, octanal, nonanal, decanal, dodecanal, tetradecanal, hexadecanal, and octadecanal. The above-mentioned modifying agent may also be one in which one or more hydrogen atoms have been substituted with a halogen or the like. The above-mentioned modifying agents may be used alone or in combination of two or more kinds.

When PVA (A) is a modified PVA in which a modifying group has been introduced by esterification, the modifying agent used for introducing the modifying group by esterification is not particularly limited, and examples thereof include carboxylic acid derivatives such as linear, branched, cyclic saturated, cyclic unsaturated, or aromatic carboxylic acids having 1 to 19 carbon atoms, carboxylic acid halides, vinyl esters, and fatty acids. Specific examples include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, and acid chlorides thereof. The above-mentioned modifying agent may be, for example, one or more hydrogen atoms substituted with halogens or the like. The above-mentioned modifying agents may be used alone or in combination of two or more kinds.

In one embodiment of the present invention, from the viewpoint of biodegradability and production costs, it is preferable that PVA (A) is an unmodified PVA that has not been modified. Here, unmodified PVA refers to PVA in which no units or functional groups other than units derived from vinyl ester monomers have been introduced into the side chains, and the structural units excluding the terminals are essentially composed of only vinyl alcohol units and vinyl ester units, and such PVA is obtained by polymerizing and saponifying vinyl ester monomers. However, the terminals of unmodified PVA may have structures other than vinyl alcohol units and vinyl ester units derived from a polymerization initiator, a chain transfer agent, etc.

In the production of PVA (A), for example, methods for obtaining a vinyl ester polymer from a vinyl ester monomer include bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, dispersion polymerization, etc. Among these, the solution polymerization method is industrially preferred.

In preparing the vinyl ester polymer, a polymerization initiator may be used. The polymerization initiator may be selected from known initiators depending on the polymerization method. Specific examples include azo initiators such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile); percarbonate compounds such as diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, and diethoxyethyl peroxydicarbonate; perester compounds such as t-butyl peroxyneodecanate, α-cumyl peroxyneodecanate, and t-butyl peroxydecanate; acetylcyclohexylsulfonyl peroxide; and peroxide initiators such as 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate.

The amount of polymerization initiator may be appropriately determined depending on the type of monomer or initiator used, the desired degree of polymerization, etc., but is preferably 0.20 to 0.33% by mass based on the total mass of the vinyl ester monomer.

In preparing the vinyl ester polymer, a chain transfer agent may be used. The chain transfer agent may be selected from known chain transfer agents depending on the polymerization method. Specific examples include aldehydes such as acetaldehyde and propionaldehyde; ketones such as acetone and methyl ethyl ketone; halogenated hydrocarbons such as trichloroethylene and perchloroethylene; and phosphinates such as sodium phosphinate monohydrate. Among these, aldehydes and ketones are preferably used. The amount of the chain transfer agent is not particularly limited as long as it can be determined to the intended degree of polymerization of the vinyl ester polymer (e.g., the desired degree of polymerization) according to the chain transfer constant of the chain transfer agent to be added. In addition, functional groups may be introduced using them, and an aliphatic hydrocarbon group may be introduced at the end using a chain transfer agent having an alkyl group, or an ionic functional group may be introduced at the end using a chain transfer agent having a carboxy group.

Polymerization conditions, etc. may be appropriately determined depending on the type and amount of monomer used, the desired physical properties, the polymerization method employed, etc. For example, the polymerization temperature is usually 0 to 150°C, preferably 20 to 120°C.

The polymerization rate in the vinyl ester polymer may be, for example, 20 to 95%. From the viewpoint of improving the yield and controlling the degree of polymerization, the polymerization rate is preferably 30% or more, and more preferably 40% or more.

The saponification reaction of the obtained vinyl ester polymer can be carried out by alcoholysis or hydrolysis using a conventionally known basic catalyst such as sodium hydroxide, potassium hydroxide, or sodium methoxide, or an acidic catalyst such as p-toluenesulfonic acid. Solvents used in the saponification reaction include alcohols such as methanol and ethanol; esters such as methyl acetate and ethyl acetate; ketones such as acetone and methyl ethyl ketone; and aromatic hydrocarbons such as benzene and toluene. These may be used alone or in combination of two or more. Of these, the saponification reaction is preferably carried out in the presence of sodium hydroxide, which is a basic catalyst, using methanol or a mixed solution of methanol and methyl acetate as the solvent.

The amount of catalyst used in the saponification reaction may be appropriately determined depending on the type of catalyst used, the desired degree of saponification, etc. For example, when sodium hydroxide is used as a catalyst for the saponification reaction, in one embodiment of the present invention, the ratio (molar ratio) of the catalyst to the vinyl ester monomer in the vinyl ester copolymer is preferably 0.0015 to 0.0095.

In the agricultural coating composition, the PVA (A) is preferably 2 to 10% by weight based on the total weight of the agricultural coating composition.

In one embodiment, the agricultural coating composition preferably contains inorganic fine particles. The inorganic fine particles are preferably at least one selected from the group consisting of talc, mica, diatomaceous earth, limestone, gypsum, bentonite, vermiculite, zeolite, silica sand, and barium sulfate, more preferably talc and/or mica, and even more preferably talc. The average particle size of the inorganic fine particles is preferably 0.1 μm or more and 100 μm or less, more preferably 1 μm or more and 80 μm or less, even more preferably 5 μm or more and 60 μm or less, and even more preferably 10 μm or more and 50 μm or less.

In the agricultural coating composition, the mass ratio of inorganic fine particles to PVA (A) is preferably 0.5:1.0 to 5.0:1.0, more preferably 0.6:1.0 to 3.0:1.0, and even more preferably 0.7:1.0 to 1.0:1.0.

The agricultural coating composition may further contain a pesticide. Here, the pesticide means an agent that prevents or reduces damage to seeds from living organisms, and is preferably at least one selected from the group consisting of insecticides, fungicides, and nematocides.

In one embodiment, the pesticide is preferably a hydrophobic pesticide, where the hydrophobic pesticide is one that does not itself dissolve in water or cannot be stably dispersed in water (e.g., without a surfactant).

The hydrophobic pesticide is not particularly limited, but may be a hydrophobic pesticide that is generally commercially available, and is preferably at least one selected from the group consisting of pyraclostrobin, fluxapyroxad, ipconazole, trifloxystrobin, metalaxyl, fludioxonil, thiabendazole, triticonazole, imidacloprid, and tefluthrin.

The insecticide is preferably at least one selected from the group consisting of clothianidin, tefluthrin, terbufos, cypermethrin, thiodicarb, lindane, furathiocarb, and acephate.

In one embodiment, the agricultural coating composition may be a solution containing a solvent. The solvent is preferably water, and the water may be ion-exchanged water. In one embodiment, the agricultural coating composition may contain alcohol as a solvent, but the alcohol content is preferably 20% by weight or less, more preferably 10% by weight or less, even more preferably 5% by weight or less, and even more preferably the alcohol content is 0, i.e., the agricultural coating composition is substantially free of alcohol.

In one embodiment, when the agricultural coating composition is a solution, its solids concentration is not particularly limited, but is preferably 30 to 50% by weight based on the total weight of the agricultural coating composition. Furthermore, for example, an agricultural coating composition having such a solids concentration of 30 to 50% by weight may be diluted to any suitable concentration with a medium such as water when used. The solids concentration of the agricultural coating composition when used may be, for example, 1 to 10% by weight.

In one embodiment, depending on the PVA (A) and any other raw materials, the agricultural coating composition may be in the form of, for example, a solution, dispersion, emulsion, suspension, etc. For example, some of the components contained in the agricultural coating composition may be in solution, while other components may be dispersed, emulsified and/or suspended. In such an embodiment, for example, when the agricultural coating composition is used for seed coating, the components of the composition are preferably substantially uniformly distributed (dispersed or mixed) before application to the seed. Thus, the agricultural coating composition is preferably a stable solution, dispersion, emulsion, or suspension in which the components can be readily uniformly distributed by conventional means, such as stirring with or without gentle heating.

In one embodiment, the agricultural coating composition may be formulated with other polymers that are compatible with PVA (e.g., can function as a binder and are water-soluble), such as polyvinylpyrrolidone, starch, and high molecular weight polyethylene glycol, to enhance coating performance. In the above embodiment, at least one selected from the group consisting of plasticizers, inorganic fine particles, pigments, and detackifiers may be added to the agricultural coating composition in the form of a solution, dispersion, emulsion, or suspension. As the pigment, anthraquinone, triphenylmethane, phthalocyanine, diazonium salts, azo compounds, metal oxides, cyano complexes, carbon black, and derivatives thereof are preferred. The pigment may be one type, or two or more types may be combined. For example, iron oxide, TiO ₂ , Prussian Blue (CAS No. 14038-43-8), Pigment Red 112 (CAS No. 6535-46-2), Pigment Red 2 (CAS No. 6041-94-7), Pigment Red 48:2 (CAS No. 7023-61-2), Phthalocyanine Blue (CAS No. 147-14-8), Pigment Green 36 (CAS No. 14302-13-7), Pigment Green 7 (CAS No. 1328-53-6), Pigment Yellow 74 (CAS No. 6358-31-2), Pigment Orange 5 (CAS No. 3468-63-1), Pigment Violet 23 (CAS No. No. 6358-30-1), and Pigment Black 7 (CAS Nos. 97793-37-8, 1333-86-4, 12768-98-8). The content of the pigment is preferably 0.1% or more and 10% or less, more preferably 0.3% or more and 5% or less, and even more preferably 0.5% or more and 2% or less, based on the solid content of the agricultural coating composition. In order to increase the adhesion of PVA (A) to the seed surface, a polyhydric alcohol such as trimethylolpropane, glycerin, or propylene glycol may be added.

In one embodiment, the agricultural coating composition may be blended with any surfactant to enhance the dispersion stability of the contents. Examples of the surfactant include alkyl sulfates, alkyl sulfonates, alkylbenzene sulfonates, polyoxyalkylene alkyl ether sulfates (alkyl ether sulfates), polyoxyalkylene alkyl ether carboxylates (alkyl ether acetates), α-olefin sulfonates, phosphate salts, acyl amino acid salts, acyltaurate salts, acyl lactates, soaps (higher fatty acids), alkyl sulfosuccinates, acyl hydrolyzed collagen salts, and acyl isethionates. Among these, at least one surfactant selected from the group consisting of alkyl sulfates and acyl amino acid salts is preferred, and alkyl sulfates are more preferred. As the alkyl sulfate, sodium dodecyl sulfate is preferred. The content of the surfactant is preferably 1% by weight or more and 10% by weight or less, more preferably 1.5% by weight or more and 5% by weight or less, and even more preferably 2% by weight or more and 3% by weight or less, based on the PVA (A).

In one embodiment, the agricultural coating composition may be formulated with any wax to enhance the seed coating ability. Natural waxes, synthetic waxes, etc. may be used as the wax.

Regarding natural waxes, any wax derived from animals, plants, crude oil, minerals, etc. can be used. For example, animal-derived waxes include beeswax, shellac wax, and privet wax, plant-derived waxes include carnauba wax, candelilla wax, rice wax, and Japan wax, crude oil-derived waxes include paraffin wax, microcrystalline wax, and slack wax, and mineral-derived waxes include montan wax, ceresin, and ozokerite.

As for synthetic waxes, any wax can be used, such as polyethylene wax, polypropylene wax, Fischer-Tropsch wax, etc.

As for wax, it is more preferable to use natural wax or Fischer-Tropsch wax because they are biodegradable and have a low environmental impact.

The method for coating agricultural materials such as seeds with the agricultural coating composition is not particularly limited, and for example, the seeds may be mixed with the agricultural coating composition, or the seeds may be sprayed with the agricultural coating composition. The coating method may be a batch method or a continuous coating method. A coating machine may be used for coating, and examples of the coating machine include a rotary coater, a drum coater, and a fluidized bed.

<Coated seeds>
One embodiment of the present invention is a coated seed, at least a part of the surface of which is coated with the above-mentioned agricultural coating composition. In one embodiment, by coating the seed with the agricultural coating composition together with the pesticide, it is possible to provide a seed with a high germination rate and with less peeling of the pesticide from the seed.

Seeds include, for example, wheat, barley, rye, oats, rice, sorghum, apples, pears, plums, peaches, almonds, cherries, strawberries, raspberries, blackberries, sugar beets, fodder beets, beans, lentils, peas, soybeans, oilseed rape, mustard, poppies, olives, sunflowers, coconuts, castor beans, cocoa beans, mallow, cucumbers, melons, cotton, flax, hemp, jute, oranges, lemons, grapefruit, mandarins, spinach, lettuce, asparagus, cabbage, carrots, onions, tomatoes, potatoes, paprika, avocados, flowers, shrubs, broad-leaved trees, fruit plants, tomatoes, peppers, potatoes, bulbs, corn, tobacco, nuts, coffee, and sugar cane, and are preferably selected from the group consisting of corn, wheat, and soybeans.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The viscosity average polymerization degree, saponification degree, retention time RT, amount of dust generation, and biodegradability of PVA (A) in the composition were measured by the following methods.

[Viscosity average degree of polymerization]
The viscosity average degree of polymerization of PVA-1 to 4 was measured in accordance with JIS K6726: 1994. Specifically, when the degree of saponification of PVA-1 to 4 was less than 99.5 mol%, the PVA-1 to 4 was saponified until the degree of saponification reached 99.5 mol% or more, and the viscosity average degree of polymerization of the obtained PVA-1 to 4 was calculated by the following formula using the intrinsic viscosity [η] (liter/g) measured in water at 30°C.
Viscosity average degree of polymerization = ([η]×10 ⁴ /8.29) ^(1/0.62)

[Saponification degree]
The saponification degrees (mol %) of PVA-1 to PVA-4 were measured in accordance with JIS K 6726:1994.

[PVA retention time RT]
The retention times RT of PVA-1 to 4 are the retention times of the peak tops measured by reversed-phase partition gradient high performance liquid chromatography using a mixture of ion-exchanged water and ethanol as an eluent. The measurements were performed under the following conditions. The "peak top" is the point at which the detection intensity in the chromatogram obtained by the chromatography measurement is the maximum and is a local maximum value.

<Measurement conditions>
Column: Shimpack G-ODS (4) (Shimadzu Corporation, octadecyl-modified spherical fully porous silica gel, inner diameter 4 mm × length 10 mm, particle size 5 μm)
Column temperature: 45°C
Eluent: ion-exchanged water (X), ethanol (purity 99.5%) (Y)
Eluent composition at each measurement time (wherein the concentration is based on volume);
0 to 5 minutes: (Y) Concentration 5% constant 5 to 25 minutes: (Y) Concentration 5 to 100%
25-40 minutes: (Y) concentration 100% constant 40-41 minutes: (Y) concentration 100-5%
41-55 minutes: (Y) Concentration 5% constant mobile phase flow rate: 0.4 mL/min
Sample concentration: 5 mg/mL
Detector: ELSD-LTII (Shimadzu Corporation, drift tube temperature 40°C, gain 6 (=32 times), _N2 gas spray pressure primary 0.4 MPa, secondary 0.35 MPa, data acquisition interval: 1000 ms, filter: 1 sec.)
Injection volume: 5μL
Length from injection to column inlet: 900 mm
Length from column outlet to nebulizer of ELSD-LTII detector: 1375 mm
Pipe diameter: 0.3 mm ID

[Amount of dust generated]
100 g of the coated seeds were placed in a 300 mL wide-mouthed plastic bottle, which was then capped and placed on a small ball mill rotating stand (AV-1, manufactured by Asahi Rika Seisakusho Co., Ltd.) and rotated at 80 rpm for 15 minutes. The treated coated seeds were sieved through a metal sieve to remove fine powder, and the weight of the coated seeds after fine powder removal was measured using a precision balance. The weight loss before and after fine powder removal was taken as the amount of dust generated.

[Biodegradability of resin components]
Regarding PVA-1 to 4, and the resin component Em-1 used in Comparative Examples 7 to 9 (a resin component having the same composition as the latex carrier described in Table 1 of WO 2013/166020), biodegradability evaluation was carried out in accordance with ISO14851 (BOD measurement using activated sludge), with A being assigned to those that were decomposed by 60% or more within 28 days in water, and B being assigned to those that were decomposed by less than 60%.

[Production Example 1]
A 3L reaction tank equipped with a stirrer, a nitrogen inlet, an additive inlet and an initiator inlet was charged with 480 g of vinyl acetate and 1120 g of methanol, and the temperature was raised to 60°C, after which the system was substituted with nitrogen by nitrogen bubbling for 30 minutes. The temperature inside the reaction tank was adjusted to 60°C, and 1.2 g of 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) was added to initiate polymerization. The polymerization temperature was maintained at 60°C during polymerization, and after 5 hours, when the polymerization rate reached 70%, the polymerization was stopped by cooling. Next, unreacted vinyl acetate was removed under reduced pressure to obtain a methanol solution of polyvinyl acetate. A methanol solution of NaOH (10% concentration) was added to a methanol solution of polyvinyl acetate adjusted to 30% so that the alkali molar ratio (moles of NaOH/moles of vinyl ester units in polyvinyl acetate) was 0.0025, and PVA-1 was obtained as PVA (A). The degree of saponification, viscosity average degree of polymerization, and retention time RT of the resulting PVA-1 are shown in Table 1.

[Production Example 2]
A 3L reaction tank equipped with a stirrer, a nitrogen inlet, an additive inlet and an initiator inlet was charged with 720 g of vinyl acetate and 880 g of methanol, and the temperature was raised to 60°C, after which the system was substituted with nitrogen by nitrogen bubbling for 30 minutes. The temperature inside the reaction tank was adjusted to 60°C, and 1.2 g of 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) was added to initiate polymerization. The polymerization temperature was maintained at 60°C during polymerization, and after 5 hours, when the polymerization rate reached 70%, the polymerization was stopped by cooling. Next, unreacted vinyl acetate was removed under reduced pressure to obtain a methanol solution of polyvinyl acetate. A methanol solution of NaOH (10% concentration) was added to a methanol solution of polyvinyl acetate adjusted to 30% so that the alkali molar ratio (moles of NaOH/moles of vinyl ester units in polyvinyl acetate) was 0.0037, and PVA-2 not corresponding to PVA (A) was obtained by saponification. The degree of saponification, viscosity average degree of polymerization, and retention time RT of the resulting PVA-2 are shown in Table 1.

[Production Example 3]
A 3L reaction tank equipped with a stirrer, a nitrogen inlet, an additive inlet and an initiator inlet was charged with 720 g of vinyl acetate and 880 g of methanol, and the temperature was raised to 60°C, after which the system was substituted with nitrogen by nitrogen bubbling for 30 minutes. The temperature inside the reaction tank was adjusted to 60°C, and 1.2 g of 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) was added to initiate polymerization. The polymerization temperature was maintained at 60°C during polymerization, and after 5 hours, the polymerization was stopped by cooling when the polymerization rate reached 70%. Next, unreacted vinyl acetate was removed under reduced pressure to obtain a methanol solution of polyvinyl acetate. A methanol solution of NaOH (10% concentration) was added to a methanol solution of polyvinyl acetate adjusted to 30% so that the alkali molar ratio (moles of NaOH/moles of vinyl ester units in polyvinyl acetate) was 0.0073, and PVA-3 not corresponding to PVA (A) was obtained by saponification. The degree of saponification, viscosity average degree of polymerization, and retention time RT of the resulting PVA-3 are shown in Table 1.

[Production Example 4]
A 3L reaction tank equipped with a stirrer, a nitrogen inlet, an additive inlet and an initiator inlet was charged with 720 g of vinyl acetate and 880 g of methanol, and the temperature was raised to 60°C, after which the system was substituted with nitrogen by nitrogen bubbling for 30 minutes. The temperature inside the reaction tank was adjusted to 60°C, and 1.2 g of 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) was added to initiate polymerization. The polymerization temperature was maintained at 60°C during polymerization, and after 5 hours, the polymerization was stopped by cooling when the polymerization rate reached 70%. Next, unreacted vinyl acetate was removed under reduced pressure to obtain a methanol solution of polyvinyl acetate. A methanol solution of NaOH (10% concentration) was added to a methanol solution of polyvinyl acetate adjusted to 30% so that the alkali molar ratio (moles of NaOH/moles of vinyl ester units in polyvinyl acetate) was 0.03, and PVA-4, which does not correspond to PVA (A), was obtained by saponification. The degree of saponification, viscosity average degree of polymerization, and retention time RT of the obtained PVA-4 are shown in Table 1.

[Example 1]
A seed coating composition was prepared according to the method described below using PVA-1 as the resin component and mica (MICA C-4000, manufactured by IMERYS, average particle size 14 μm) as the inorganic fine particles, and this was designated as agricultural coating composition Coat-1.

(Preparation of agricultural coating composition)
10 g of inorganic fine particles, 2.9 g of phthalocyanine blue (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) as a pigment, and 18.6 g of deionized water were mixed until uniform to prepare a pigment dispersion. Next, 3.2 g of resin component, 83 mg of sodium dodecyl sulfate (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) (2.6% by weight relative to PVA-1), and 37.8 g of ion-exchanged water were mixed until uniform to prepare an 8 wt% aqueous solution of the resin component. 19.7 g of an 8 wt% aqueous solution of the resin component, 4.46 g of the pigment dispersion, and 20.84 g of water were mixed until uniform, and the obtained product was used as an agricultural coating composition. The solid content concentration of the obtained agricultural coating composition was 7.5%, and the solid content was 3.5% of the resin component, 3.1% of the inorganic fine particles, and 0.9% of the pigment.

(Seed Coating)
8 mL of the agricultural coating composition was added to 200 g of corn seeds (pop variety, butterfly type), and coating was performed using a dry pan type granulator (DPZ-01R, AS ONE Corporation). The coating was performed at a temperature of 35 to 40° C., a rotation speed of 20 rpm, an angle of 30 degrees, and a drying time of 40 minutes to obtain coated seeds.

[Example 2]
An agricultural coating composition Coat-2 was obtained in the same manner as in Example 1, except that talc (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd., average particle size 34 μm) was used as the inorganic fine particles. The solid content of the obtained agricultural coating composition was 7.5%, and the solid content was 3.5% resin component, 3.1% inorganic fine particles, and 0.9% pigment.

[Example 3]
An agricultural coating composition Coat-3 was obtained in the same manner as in Example 1, except that talc (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd., average particle size 34 μm) was used as the inorganic fine particles and 3.3 g of polyethylene wax (product name "Liquitron 461", manufactured by Lubrizol) was added as an additional additive. The solid content concentration of the obtained agricultural coating composition was 10.4%, and the solid content was 3.3% resin component, 3.3% polyethylene wax, 2.9% inorganic fine particles, and 0.9% pigment.

[Comparative Example 1]
Except for using PVA-2 as the resin component and not adding sodium dodecyl sulfate, an agricultural coating composition Coat-4 was obtained in the same manner as in Example 1. The solid content of the obtained agricultural coating composition was 7.5%, and the solid content was 3.5% of the resin component, 3.1% of the inorganic fine particles, and 0.9% of the pigment.

[Comparative Example 2]
Except for using talc (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd., average particle size 34 μm) as the inorganic fine particles, an agricultural coating composition Coat-5 was obtained in the same manner as in Comparative Example 1. The solid content concentration of the obtained agricultural coating composition was 7.5%, and the solid content was 3.5% resin component, 3.1% inorganic fine particles, and 0.9% pigment.

[Comparative Example 3]
Except for using PVA-3 as the resin component, an agricultural coating composition Coat-6 was obtained in the same manner as in Comparative Example 1. The solid content of the obtained agricultural coating composition was 7.5%, and the solid content was 3.5% for the resin component, 3.1% for the inorganic fine particles, and 0.9% for the pigment.

[Comparative Example 4]
Except for using talc (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd., average particle size 34 μm) as the inorganic fine particles, an agricultural coating composition Coat-7 was obtained in the same manner as in Comparative Example 3. The solid content of the obtained agricultural coating composition was 7.5%, and the solid content was 3.5% resin component, 3.1% inorganic fine particles, and 0.9% pigment.

[Comparative Example 5]
Except for using PVA-3 as the resin component, an agricultural coating composition Coat-8 was obtained in the same manner as in Example 1. The solid content of the obtained agricultural coating composition was 7.5%, and the solid content was 3.5% for the resin component, 3.1% for the inorganic fine particles, and 0.9% for the pigment.

[Comparative Example 6]
Except for using PVA-4 as the resin component, an agricultural coating composition Coat-9 was obtained in the same manner as in Comparative Example 4. The solid content of the obtained agricultural coating composition was 7.5%, and the solid content was 3.5% for the resin component, 3.1% for the inorganic fine particles, and 0.9% for the pigment.

[Comparative Example 7]
Coat-10 was an agricultural coating composition prepared in the same manner as in Example 1 except that Em-1 was used as the resin component, 3.3 g of polyethylene wax (trade name "Liquitron 461", manufactured by Lubrizol) was added as an additional additive, the amount of deionized water used was changed to 17.54 g, and sodium dodecyl sulfate was not added. The solid content concentration of the obtained agricultural coating composition was 11%, and the solid content was 3.5% of the resin component, 3.5% of the polyethylene wax, 3.1% of inorganic fine particles, and 0.9% of the pigment. Em-1 is a resin component (a random copolymer containing 15% by mass of styrene, 69% by mass of butyl acrylate, 12% by mass of acrylonitrile, and 5% by mass of acrylic acid, polymer solid content 47%) having the same composition as the latex carrier described in Table 1 of Patent Document 1 (WO 2013/166020).

[Comparative Example 8]
Except for using Em-1 as the resin component and not adding sodium dodecyl sulfate, an agricultural coating composition Coat-11 was obtained in the same manner as in Example 1. The solid content of the obtained agricultural coating composition was 7.5%, and the solid content was 3.5% of the resin component, 3.1% of the inorganic fine particles, and 0.9% of the pigment.

[Comparative Example 9]
Except for using talc (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) as the inorganic fine particles, an agricultural coating composition Coat-12 was obtained in the same manner as in Comparative Example 7. The solid content of the obtained agricultural coating composition was 11%, and the solid content was 3.5% resin component, 3.5% polyethylene wax, 3.1% inorganic fine particles, and 0.9% pigment.

The results of dust generation and biodegradability for Examples 1 to 3 and Comparative Examples 1 to 9 are summarized in Table 2 (and Table 3-4, which is organized by inorganic fine particles used). The agricultural coating compositions of Examples 1 to 3 were agricultural coating compositions that satisfied both low dust generation and biodegradability. The RT of PVA in Comparative Examples 1, 3, and 5 was less than 22 minutes, and the dust generation was inferior to that of Example 1, which was an example using the same mica as the inorganic fine particles. Comparative Examples 2, 4, and 6 were also examples in which the RT of PVA was less than 22 minutes, and the dust generation was inferior to that of Examples 2 and 3, which used talc as the inorganic fine particles. The agricultural coating compositions of Comparative Examples 7 to 9 did not contain PVA (A) as a resin component but contained a styrene-acrylate copolymer, and therefore the biodegradability was inferior.

Claims (10)

An agricultural coating composition containing a vinyl alcohol polymer (A) having a peak top retention time (RT) of 22 minutes or more as measured by reversed-phase partition gradient high-performance liquid chromatography using a water-ethanol eluent. The agricultural coating composition according to claim 1, wherein the degree of saponification of the vinyl alcohol polymer is less than 70.0 mol%. The agricultural coating composition according to claim 2, wherein the vinyl alcohol polymer (A) is an unmodified vinyl alcohol polymer. The agricultural coating composition according to claim 1, further comprising inorganic fine particles. The agricultural coating composition according to claim 4, wherein the inorganic fine particles are at least one selected from the group consisting of talc, mica, diatomaceous earth, limestone, gypsum, bentonite, vermiculite, zeolite, silica sand, and barium sulfate. The agricultural coating composition according to claim 5, wherein the inorganic fine particles include talc. The agricultural coating composition according to claim 4, wherein the mass ratio of the inorganic fine particles to the vinyl alcohol polymer is 0.5:1.0 to 5.0:1.0. The agricultural coating composition according to claim 1, wherein the agricultural coating composition is a seed coating composition. A coated seed, at least a portion of the surface of which is coated with the agricultural coating composition according to any one of claims 1 to 7. The coated seed of claim 9, wherein the seed is selected from the group consisting of corn, wheat, and soybean.