Coating composition for agricultural use, and coated seed

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

[0001] 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-based polymer and to coated seeds.

[0002] Agricultural coating compositions used to coat agricultural materials, such as seed coating compositions, are widely used to coat seeds and increase the probability that the seeds will grow into crops. To prevent seeds from being infested by saprophytic fungi or insects before germination, pesticides are often added to such seed coating compositions. However, conventional seed coating compositions containing pesticides coated on seeds often peel off and spread into the surrounding environment, causing adverse effects on workers and environmental organisms. Known methods for reducing pesticide peeling from seeds include binders primarily composed of polyacrylic acid esters that have high adhesion to seed surfaces (Patent Document 1) and glossy seed coating materials containing a lustrous material, talc, polyvinyl alcohol, an ethylene-vinyl acetate copolymer, and an aqueous medium (Patent Document 2). However, these documents do not disclose agricultural coating compositions, such as seed coating compositions, that are biodegradable and exhibit reduced peeling from seeds.

[0003] International Publication No. WO 2013 / 166020 International Publication No. WO 2019 / 176272

[0004] An object of the present invention is to provide an agricultural coating composition that is biodegradable and generates little dust, and coated seeds that are coated with the agricultural coating composition.

[0005] The above object is achieved by an agricultural coating composition containing a vinyl alcohol-based 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 containing a vinyl alcohol-based 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. [2] The agricultural coating composition according to [1], wherein the vinyl alcohol-based polymer has a degree of saponification of less than 70.0 mol%. [3] The agricultural coating composition according to [2], wherein the vinyl alcohol-based polymer (A) is an unmodified vinyl alcohol-based polymer. [4] The agricultural coating composition according to [1], wherein the agricultural coating composition further contains 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 comprise talc. [7] The agricultural coating composition according to [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. [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, at least a portion of the surface of which 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 selected from the group consisting of corn, wheat, and soybean.

[0006] The agricultural coating composition of the present invention is excellent in that it is biodegradable and generates little dust.

[0007] In this specification, a numerical range described using "to" means that the numerical values ​​before and after "to" are included as the lower and upper limits. In this specification, the upper and lower limits of numerical ranges (contents, physical properties, etc.) can be combined as appropriate.

[0008] <Agricultural Coating Composition> The agricultural coating composition of the present invention is an agricultural coating composition containing a vinyl alcohol-based polymer (A) having a peak top retention time RT of 22 minutes or longer as measured by reversed-phase partition gradient high-performance liquid chromatography using a water-ethanol eluent. Hereinafter, "vinyl alcohol-based polymer" may be referred to as "PVA," and the vinyl alcohol-based polymer (A) satisfying the above-mentioned specified requirements may be referred to as PVA (A).

[0009] 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 seed coating composition. Another preferred embodiment of the present invention is an agricultural coating composition used to coat agricultural materials other than seeds. Examples of agricultural materials other than seeds include fertilizer, soil, sand, and stones. Among these, it is preferred that the agricultural coating composition is a fertilizer coating composition that coats fertilizer.

[0010] 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 the 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%. That is, the preferred ratio of vinyl alcohol units to all structural units in the PVA (A) is, for example, 10 to 90 mol%, and each of the above-mentioned preferred ranges is suitable. The PVA (A) may be obtained, for example, by polymerizing a vinyl ester monomer and saponifying the resulting vinyl ester polymer, and the PVA (A) may contain, for example, vinyl ester units in addition to vinyl alcohol units.

[0011] PVA(A) has a peak top retention time (RT) of 22 minutes or longer when measured by reversed-phase gradient high-performance liquid chromatography using a water-ethanol eluent. Here, "peak top" refers to the point where the detected intensity in the chromatogram obtained by chromatography is maximum and is a local maximum, and refers to the peak top originating from PVA(A). Such PVA is highly hydrophobic and exhibits superior adhesive strength between the PVA and the seed surface. This is thought to be due to the fact that the highly hydrophobic PVA adsorbs onto the seed surface, thereby improving the adhesive strength between the PVA and the seed surface. PVA(A) preferably has a retention time RT of greater than 22 minutes. Furthermore, PVA(A) preferably has a retention time RT of 25 minutes or shorter. In other words, a suitable range for the retention time RT is, for example, 22 to 25 minutes, and the above-mentioned preferred range is suitable. PVA(A) with a RT of 22 minutes < RT < 25 minutes is more preferred. The retention time RT of the PVA (A) can be adjusted by introducing a modifying group or adjusting the degree of saponification or the viscosity-average degree of polymerization.

[0012] 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 (here, concentrations are based on volume): 0 to 5 min: (Y) concentration 5% constant 5 to 25 min: (Y) concentration 5 to 100% 25 to 40 min: (Y) concentration 100% constant 40 to 41 min: (Y) concentration 100 to 5% 41 to 55 min: (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), N ２ Gas spray pressure: primary 0.4 MPa, secondary 0.35 MPa, data acquisition interval: 1000 ms, filter: 1 sec.) Injection volume: 5 μL 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

[0013] 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 saponification degree of PVA (A) is preferably in a range of, for example, 20 mol% to less than 70 mol%, and each of the above-mentioned preferred ranges of values ​​is suitable. Having the saponification degree of PVA (A) in the above range provides better adhesion (covering ability) to seed surfaces and biodegradability. The saponification degree of PVA (A) is measured by the method described in JIS K6726:1994.

[0014] 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 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. Having the viscosity-average degree of polymerization of PVA (A) in the above range provides better adhesion (covering ability) to the seed surface. The viscosity-average degree of polymerization of PVA (A) is measured in accordance with JIS K6726:1994.

[0015] 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.

[0016] The PVA (A) may be a modified PVA into which units other than units derived from vinyl ester monomers or functional groups have been introduced by using techniques such as copolymerization, acetalization, and esterification.

[0017] When the 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 the vinyl ester monomer. The monomer other than the vinyl ester-based monomer that is copolymerized with the vinyl ester-based monomer can be used as long as it is copolymerizable with the vinyl ester-based 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. Examples of suitable monomers include 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; and 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.

[0018] When the PVA (A) is a modified PVA having a modifying group introduced therein by acetalization, the modifying agent used for the introduction of the modifying group by acetalization is not particularly limited as long as the effects of the present invention are not impaired. Examples of the modifying agent include linear, branched, cyclic saturated, cyclic unsaturated, or aromatic aldehydes and aldoses having 1 to 19 carbon atoms. Specific examples 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. Furthermore, the modifying agent may be one in which one or more hydrogen atoms have been substituted with a halogen or the like. The modifying agents may be used alone or in combination of two or more.

[0019] When PVA (A) is a modified PVA having a modifying group introduced by esterification, the modifier used to introduce 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. Furthermore, the modifier may be one in which one or more hydrogen atoms have been substituted with a halogen or the like. The modifiers may be used alone or in combination.

[0020] In one embodiment of the present invention, from the viewpoints of biodegradability and production costs, the PVA (A) is preferably an unmodified PVA. Here, the unmodified PVA is a PVA in which no units or functional groups other than units derived from vinyl ester monomers are introduced into the side chains, and the structural units excluding the terminals are essentially composed of vinyl alcohol units and vinyl ester units. Such a PVA can be obtained by polymerizing and saponifying a vinyl ester monomer. However, the terminals of the unmodified PVA may contain structures other than vinyl alcohol units and vinyl ester units derived from a polymerization initiator, a chain transfer agent, etc.

[0021] In producing the 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.

[0022] A polymerization initiator may be used in the preparation of the vinyl ester polymer. 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.

[0023] The amount of the 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-based monomers.

[0024] A chain transfer agent may be used in the preparation of the vinyl ester polymer. 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 preferred. 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) depending on the chain transfer constant of the chain transfer agent added. Furthermore, functional groups may be introduced using these agents. For example, a chain transfer agent having an alkyl group may be used to introduce an aliphatic hydrocarbon group at the end, or a chain transfer agent having a carboxy group may be used to introduce an ionic functional group at the end.

[0025] The polymerization conditions and the like may be appropriately determined depending on the type and amount of the monomers 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.

[0026] The polymerization rate of the vinyl ester polymer may be, for example, 20 to 95%. From the viewpoints of improving the yield and controlling the degree of polymerization, the polymerization rate is preferably 30% or more, and more preferably 40% or more.

[0027] 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. Examples of 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 solvents may be used alone or in combination of two or more. Among these, a preferred method is to carry out the saponification reaction using methanol or a mixed solution of methanol and methyl acetate as the solvent in the presence of sodium hydroxide as a basic catalyst.

[0028] 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 the 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.

[0029] 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.

[0030] 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.

[0031] In the agricultural coating composition, the mass ratio of the inorganic fine particles to the 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.

[0032] The agricultural coating composition may further contain a pesticide. Here, the pesticide means an agent that prevents or reduces damage to seeds from organisms, and is preferably at least one selected from the group consisting of insecticides, fungicides, and nematicides.

[0033] In one embodiment, the pesticide is preferably a hydrophobic pesticide, where a hydrophobic pesticide is one that does not itself dissolve in water or cannot be stably dispersed in water (e.g., without a surfactant).

[0034] The hydrophobic pesticide is not particularly limited, but may be a generally commercially available hydrophobic pesticide, and is preferably at least one selected from the group consisting of pyraclostrobin, fluxapyroxad, ipconazole, trifloxystrobin, metalaxyl, fludioxonil, thiabendazole, triticonazole, imidacloprid, and tefluthrin.

[0035] The insecticide is preferably at least one selected from the group consisting of clothianidin, tefluthrin, terbufos, cypermethrin, thiodicarb, lindane, furathiocarb, and acephate.

[0036] 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 another embodiment, the agricultural coating composition may contain alcohol as a solvent, but the alcohol content is preferably 20 wt% or less, more preferably 10 wt% or less, and even more preferably 5 wt% or less. It is even more preferable that the alcohol content is 0, i.e., the agricultural coating composition is substantially alcohol-free.

[0037] In one embodiment, when the agricultural coating composition is a solution, its solids concentration is not particularly limited, but is preferably 30 to 50 wt % based on the total weight of the agricultural coating composition. Furthermore, for example, an agricultural coating composition having a solids concentration of 30 to 50 wt % may be diluted with a medium such as water to any suitable concentration before use. The solids concentration of the agricultural coating composition during use may be, for example, 1 to 10 wt %.

[0038] In one embodiment, depending on the PVA (A) and other optional 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 included 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, it is preferred that the components of the composition be substantially uniformly distributed (dispersed or mixed) before application to the seeds. Therefore, it is preferred that the agricultural coating composition be a stable solution, dispersion, emulsion, or suspension whose components can be easily and uniformly distributed by conventional means, such as stirring with or without gentle heating.

[0039] In one embodiment, the agricultural coating composition may be blended with other polymers compatible with PVA (e.g., capable of functioning as a binder and being water-soluble), such as polyvinylpyrrolidone, starch, or high-molecular-weight polyethylene glycol, to enhance coating performance. In the above-described embodiment, at least one selected from the group consisting of a plasticizer, the inorganic fine particles, a pigment, and a detackifier may be optionally added to the agricultural coating composition in the form of a solution, dispersion, emulsion, or suspension. Preferred pigments include anthraquinone, triphenylmethane, phthalocyanine, diazonium salts, azo compounds, metal oxides, cyano complexes, carbon black, and derivatives thereof. One type of pigment may be used, 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. 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 addition, a polyhydric alcohol such as trimethylolpropane, glycerin, or propylene glycol may be added to enhance the adhesion of the PVA (A) to the seed surface.

[0040] In one embodiment, the agricultural coating composition may be blended with any surfactant to enhance the dispersion stability of the contents. Examples of surfactants that can be used include alkyl sulfates, alkyl sulfonates, alkyl benzene sulfonates, polyoxyalkylene alkyl ether sulfates (alkyl ether sulfates), polyoxyalkylene alkyl ether carboxylates (alkyl ether acetates), α-olefin sulfonates, phosphate esters, acyl amino acid salts, acyltaurates, 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, with alkyl sulfates being more preferred. Furthermore, sodium dodecyl sulfate is preferred as the alkyl sulfate. The surfactant content is preferably 1% by weight to 10% by weight, more preferably 1.5% by weight to 5% by weight, and even more preferably 2% by weight to 3% by weight, based on the PVA (A).

[0041] In one embodiment, the agricultural coating composition may be blended with any wax to enhance its seed coating ability. The wax may be a natural wax or a synthetic wax.

[0042] Any natural wax may be used, such as wax derived from animals, plants, crude oil, minerals, etc. For example, examples of animal-derived waxes include beeswax, shellac wax, and privet wax; examples of plant-derived waxes include carnauba wax, candelilla wax, rice wax, and Japan wax; examples of crude oil-derived waxes include paraffin wax, microcrystalline wax, and slack wax; and examples of mineral-derived waxes include montan wax, ceresin, and ozokerite.

[0043] As for the synthetic wax, any wax such as polyethylene wax, polypropylene wax, or Fischer-Tropsch wax can be used.

[0044] As for the wax, it is more preferable to use natural wax or Fischer-Tropsch wax because of its biodegradability and low environmental impact.

[0045] The method for coating agricultural materials such as seeds with the agricultural coating composition is not particularly limited. For example, the seeds may be mixed with the agricultural coating composition, or the agricultural coating composition may be sprayed onto the seeds. The coating method may be a batch method or a continuous 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.

[0046] <Coated Seed> One embodiment of the present invention is a coated seed, at least a portion 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 a pesticide, it is possible to provide seeds with less peeling of the pesticide from the seed and a high germination rate.

[0047] Examples of seeds include wheat, barley, rye, oats, rice, sorghum, apples, pears, plums, peaches, almonds, cherries, strawberries, raspberries, blackberries, sugar beets, fodder beets, beans, lentils, peas, soybeans, rapeseed, 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 sugarcane, and are preferably selected from the group consisting of corn, wheat, and soybeans.

[0048] The present invention will be described in more detail below with reference to examples, but is not limited to these examples. The viscosity-average degree of polymerization, degree of saponification, retention time RT, amount of dust generation, and biodegradability of PVA (A) in the compositions were measured by the following methods.

[0049] [Viscosity Average Degree of Polymerization] The viscosity average degree of polymerization of PVA-1 to PVA-4 was measured in accordance with JIS K6726:1994. Specifically, when the degree of saponification of PVA-1 to PVA-4 was less than 99.5 mol%, the PVA-1 to PVA-4 were saponified until the degree of saponification reached 99.5 mol% or more. The viscosity average degree of polymerization of the resulting PVA-1 to PVA-4 was calculated by the following formula using the intrinsic viscosity [η] (liters / g) measured in water at 30°C. Viscosity average degree of polymerization = ([η] × 10 ４ / 8.29) （１／０．６２）

[0050] [Saponification Degree] The saponification degrees (mol %) of PVA-1 to PVA-4 were measured in accordance with JIS K 6726:1994.

[0051] [PVA Retention Time RT] The retention times RT of PVA-1 to PVA-4 are the peak top retention times measured by reversed-phase partition gradient high-performance liquid chromatography using an ion-exchanged water / ethanol mixture as the eluent. The measurement was carried out under the following conditions. The "peak top" refers to the point where the detected intensity in the chromatogram obtained by the chromatography measurement is the maximum and is a local maximum.

[0052] <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 based on volume): 0 to 5 min: (Y) concentration 5% constant 5 to 25 min: (Y) concentration 5 to 100% 25 to 40 min: (Y) concentration 100% constant 40 to 41 min: (Y) concentration 100 to 5% 41 to 55 min: (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), N ２Gas spray pressure: primary 0.4 MPa, secondary 0.35 MPa, data acquisition interval: 1000 ms, filter: 1 sec.) Injection volume: 5 μL 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

[0053] [Amount of dust generated] 100 g of coated seeds were placed in a 300 mL wide-mouth plastic bottle and the lid was then 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. After the treatment, the coated seeds were placed on 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 recorded as the amount of dust generated.

[0054] [Biodegradability of Resin Component] For 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 was evaluated in accordance with ISO 14851 (BOD measurement using activated sludge), with A being assigned to samples that were 60% or more decomposed in water within 28 days, and B being assigned to samples that were less than 60% decomposed.

[0055] [Production Example 1] 480 g of vinyl acetate and 1,120 g of methanol were charged into a 3-L reaction vessel equipped with a stirrer, a nitrogen inlet, an additive inlet, and an initiator inlet. The temperature was raised to 60°C, and the system was then purged with nitrogen by nitrogen bubbling for 30 minutes. The temperature inside the reaction vessel 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 conversion reached 70%, the polymerization was terminated by cooling. Next, unreacted vinyl acetate was removed under reduced pressure to obtain a methanol solution of polyvinyl acetate. A 10% NaOH methanol solution was added to a 30% methanol solution of polyvinyl acetate to obtain an alkali molar ratio (moles of NaOH / moles of vinyl ester units in polyvinyl acetate) of 0.0025, and saponification was performed to obtain PVA-1 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.

[0056] [Production Example 2] 720 g of vinyl acetate and 880 g of methanol were charged into a 3 L reaction vessel equipped with a stirrer, a nitrogen inlet, an additive inlet, and an initiator inlet. The temperature was raised to 60°C, and the system was then purged with nitrogen by nitrogen bubbling for 30 minutes. The temperature inside the reaction vessel 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 conversion reached 70%, the polymerization was terminated by cooling. Next, unreacted vinyl acetate was removed under reduced pressure to obtain a methanol solution of polyvinyl acetate. To a 30% methanol solution of polyvinyl acetate, a NaOH methanol solution (10% concentration) was added to obtain an alkali molar ratio (moles of NaOH / moles of vinyl ester units in polyvinyl acetate) of 0.0037, followed by saponification, to obtain PVA-2, which did not correspond to PVA (A). The degree of saponification, viscosity average degree of polymerization, and retention time RT of the resulting PVA-2 are shown in Table 1.

[0057] [Production Example 3] 720 g of vinyl acetate and 880 g of methanol were charged into a 3 L reaction vessel equipped with a stirrer, a nitrogen inlet, an additive inlet, and an initiator inlet. The temperature was raised to 60°C, and the system was then purged with nitrogen by nitrogen bubbling for 30 minutes. The temperature inside the reaction vessel 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 conversion reached 70%, the polymerization was terminated by cooling. Next, unreacted vinyl acetate was removed under reduced pressure to obtain a methanol solution of polyvinyl acetate. A 10% NaOH methanol solution was added to a 30% methanol solution of polyvinyl acetate to obtain a saponification solution with an alkali molar ratio (moles of NaOH / moles of vinyl ester units in polyvinyl acetate) of 0.0073, yielding PVA-3, which did not correspond to PVA (A). The degree of saponification, viscosity average degree of polymerization, and retention time RT of the resulting PVA-3 are shown in Table 1.

[0058] [Production Example 4] 720 g of vinyl acetate and 880 g of methanol were charged into a 3 L reaction vessel equipped with a stirrer, a nitrogen inlet, an additive inlet, and an initiator inlet. The temperature was raised to 60°C, and the system was then purged with nitrogen by nitrogen bubbling for 30 minutes. The temperature inside the reaction vessel 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 conversion reached 70%, the polymerization was terminated by cooling. Next, unreacted vinyl acetate was removed under reduced pressure to obtain a methanol solution of polyvinyl acetate. A 10% NaOH methanol solution was added to a 30% methanol solution of polyvinyl acetate to obtain a saponification solution with an alkali molar ratio (moles of NaOH / moles of vinyl ester units in polyvinyl acetate) of 0.03, and PVA-4, which did not correspond to PVA (A), was obtained. The degree of saponification, viscosity average degree of polymerization, and retention time RT of the resulting PVA-4 are shown in Table 1.

[0059] [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.

[0060] (Preparation of Agricultural Coating Composition) 10 g of inorganic fine particles, 2.9 g of phthalocyanine blue (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 (2.6 wt % based on PVA-1) of sodium dodecyl sulfate (Fujifilm Wako Pure Chemical Industries, Ltd.), 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 the 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 resulting solution was used as the agricultural coating composition. The solids concentration of the resulting agricultural coating composition was 7.5%, with the solids content being 3.5% resin component, 3.1% inorganic fine particles, and 0.9% pigment.

[0061] (Coating on seeds) 8 mL of the agricultural coating composition was added to 200 g of corn seeds (pop variety, butterfly type), and coating was carried out using a dry pan granulator (DPZ-01R, AS ONE Corporation). The coating was carried out 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.

[0062] 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 solids concentration of the obtained agricultural coating composition was 7.5%, and the solid contents were 3.5% resin component, 3.1% inorganic fine particles, and 0.9% pigment.

[0063] 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 (trade name "Liquitron 461", manufactured by Lubrizol) was added as an additional additive. The solids concentration of the obtained agricultural coating composition was 10.4%, and the solid contents were 3.3% resin component, 3.3% polyethylene wax, 2.9% inorganic fine particles, and 0.9% pigment.

[0064] Comparative Example 1 An agricultural coating composition Coat-4 was obtained in the same manner as in Example 1, except that PVA-2 was used as the resin component and sodium dodecyl sulfate was not added. The solids concentration of the obtained agricultural coating composition was 7.5%, and the solid contents were 3.5% for the resin component, 3.1% for the inorganic fine particles, and 0.9% for the pigment.

[0065] Comparative Example 2 An agricultural coating composition Coat-5 was obtained in the same manner as in Comparative 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 solids concentration of the obtained agricultural coating composition was 7.5%, and the solid contents were 3.5% resin component, 3.1% inorganic fine particles, and 0.9% pigment.

[0066] [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 solids concentration of the obtained agricultural coating composition was 7.5%, and the solid contents were 3.5% resin component, 3.1% inorganic fine particles, and 0.9% pigment.

[0067] Comparative Example 4 An agricultural coating composition Coat-7 was obtained in the same manner as in Comparative Example 3, except that talc (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., average particle size 34 μm) was used as the inorganic fine particles. The solids concentration of the obtained agricultural coating composition was 7.5%, and the solid contents were 3.5% resin component, 3.1% inorganic fine particles, and 0.9% pigment.

[0068] Comparative Example 5 An agricultural coating composition Coat-8 was obtained in the same manner as in Example 1, except that PVA-3 was used as the resin component. The solids concentration of the obtained agricultural coating composition was 7.5%, and the solid contents were 3.5% for the resin component, 3.1% for the inorganic fine particles, and 0.9% for the pigment.

[0069] [Comparative Example 6] An agricultural coating composition Coat-9 was obtained in the same manner as in Comparative Example 4, except that PVA-4 was used as the resin component. The solids concentration of the obtained agricultural coating composition was 7.5%, and the solid contents were 3.5% for the resin component, 3.1% for the inorganic fine particles, and 0.9% for the pigment.

[0070] Comparative Example 7 An agricultural coating composition designated Coat-10 was 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 resulting agricultural coating composition had a solids concentration of 11%, with the solid contents being 3.5% resin component, 3.5% polyethylene wax, 3.1% inorganic fine particles, and 0.9% pigment. Em-1 is a resin component (a random copolymer composed of 15% by mass of styrene, 69% by mass of butyl acrylate, 12% by mass of acrylonitrile, and 5% by mass of acrylic acid, polymer solids content 47%) having the same composition as the latex carrier described in Table 1 of Patent Document 1 (WO 2013 / 166020).

[0071] Comparative Example 8 An agricultural coating composition Coat-11 was obtained in the same manner as in Example 1, except that Em-1 was used as the resin component and sodium dodecyl sulfate was not added. The solids concentration of the obtained agricultural coating composition was 7.5%, and the solid contents were 3.5% for the resin component, 3.1% for the inorganic fine particles, and 0.9% for the pigment.

[0072] Comparative Example 9 An agricultural coating composition Coat-12 was obtained in the same manner as in Comparative Example 7, except that talc (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used as the inorganic fine particles. The solids concentration of the obtained agricultural coating composition was 11%, and the solid contents were 3.5% resin component, 3.5% polyethylene wax, 3.1% inorganic fine particles, and 0.9% pigment.

[0073]

[0074]

[0075]

[0076]

[0077] The results of dust generation and biodegradability for Examples 1 to 3 and Comparative Examples 1 to 9 are summarized in Table 2 (and Tables 3-4, 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 the PVA in Comparative Examples 1, 3, and 5 was less than 22 minutes, resulting in inferior dust generation compared to Example 1, which also used mica as the inorganic fine particles. Comparative Examples 2, 4, and 6 were also examples in which the RT of the PVA was less than 22 minutes, resulting in inferior dust generation compared to Examples 2 and 3, which also used talc as the inorganic fine particles. Furthermore, the agricultural coating compositions of Comparative Examples 7 to 9 did not contain PVA (A) as the resin component but contained a styrene-acrylate copolymer, resulting in inferior biodegradability.

Claims

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 claim 1, wherein the degree of saponification of said vinyl alcohol polymer is less than 70.0 mol %.

3. The agricultural coating composition according to claim 2, wherein the vinyl alcohol polymer (A) is an unmodified vinyl alcohol polymer.

4. The agricultural coating composition of claim 1, wherein said agricultural coating composition further comprises inorganic particulates.

5. 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.

6. The agricultural coating composition of claim 5, wherein said inorganic particulate comprises talc.

7. 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.

8. The agricultural coating composition of claim 1, wherein said agricultural coating composition is a seed coating composition.

9. A coated seed, at least a part of the surface of which is coated with the agricultural coating composition according to any one of claims 1 to 7.

10. The coated seed of claim 9, wherein the seed is selected from the group consisting of corn, wheat and soybean.

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