Seed coating material and coated seed

Abstract

Provided are a seed coating material that is biodegradable, generates little dust, and exhibits excellent seed coatability, and a coated seed that is coated by this seed coating material. The seed coating material contains a vinyl alcohol-based polymer and optional sodium acetate. The ratio of the total content of the methanol-soluble component of the vinyl alcohol-based polymer plus the sodium acetate to the total content of the vinyl alcohol-based polymer plus the sodium acetate is 2 to 20 mass%.

Description

Seed coating materials and coated seeds

[0001] The present invention relates to a seed coating material containing a vinyl alcohol polymer, and to coated seeds obtained by using the same.

[0002] Seed coating materials are widely used to coat seeds and increase the probability that the seeds will develop into crops. To prevent seeds from being infested by saprophytic fungi or insects before germination, pesticides are often added to these seed coating materials. However, conventional seed coating materials containing pesticides often peel off and spread into the surrounding environment, adversely affecting 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 glittering material, talc, polyvinyl alcohol, ethylene-vinyl acetate copolymer, and an aqueous medium (Patent Document 2). However, these documents do not disclose seed coating materials that are biodegradable and exhibit minimal peeling from seeds.

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

[0004] The present invention aims to provide a seed coating material that is biodegradable, generates little dust, and has excellent seed coating properties, and to provide coated seeds that are coated with the seed coating material.

[0005] The object is to provide a seed coating material comprising: [1] a vinyl alcohol-based polymer and optionally sodium acetate, wherein the ratio of the total content of the methanol-soluble content of the vinyl alcohol-based polymer and the sodium acetate to the total content of the vinyl alcohol-based polymer and the sodium acetate is 2% by mass or more and 20% by mass or less; [2] the seed coating material of [1], wherein the ratio of the methanol-soluble content of the vinyl alcohol-based polymer in the vinyl alcohol-based polymer is 4% by mass or more and 10% by mass or less; [3] the seed coating material of [1] or [2], wherein the saponification degree of the vinyl alcohol-based polymer is 70.0 mol% or more and 86.0 mol% or less; [4] the seed coating material of any of [1] to [3], further comprising inorganic fine particles; [5] the seed coating material of [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 seed coating material of [5], wherein the inorganic fine particles include talc; [7] The seed coating material of any one of [4] to [6], 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] A coated seed, the surface of at least a part of which is coated with the seed coating material of any one of [1] to [7]; [9] The coated seed of [8], wherein the seed is at least one kind selected from the group consisting of corn, wheat, and soybean.

[0006] The seed coating material of the present invention is biodegradable, generates little dust, and has excellent seed coating properties.

[0007] Fig. 1 is a photograph of the coated seeds of Example 2. Fig. 2 is a photograph of the coated seeds of Comparative Example 3.

[0008] Hereinafter, embodiments of the present invention will be described. In this specification, a numerical range indicated using "to" includes the numerical values ​​before and after "to".

[0009] <Seed coating material> The seed coating material of the present invention contains a vinyl alcohol-based polymer (hereinafter may be referred to as "PVA") and optionally sodium acetate, and the ratio of the total content of the methanol-soluble matter of the PVA and the sodium acetate to the total content of the PVA and the sodium acetate is 2% by mass or more and 20% by mass or less.

[0010] The PVA contained in the seed coating material of the present invention is a polymer having vinyl alcohol units as structural units. The lower limit of the proportion of vinyl alcohol units to all structural units in the PVA 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 proportion of vinyl alcohol units is, for example, preferably 90 mol%, more preferably 80 mol%, and even more preferably 60 mol%. The PVA may be obtained, for example, by polymerizing a vinyl ester monomer and saponifying the resulting vinyl ester polymer. In addition to vinyl alcohol units, the PVA may contain, for example, vinyl ester units.

[0011] In the present invention, the "methanol-soluble fraction of PVA" (hereinafter also simply referred to as "methanol-soluble fraction") refers to a PVA component that is soluble in methanol among PVA components. Specifically, it refers to a PVA component that dissolves in the washing solution when PVA is washed with methanol using a Soxhlet washer for 8 hours. The amount of methanol is 100 mL per 10 g of PVA. Washing using a Soxhlet washer is performed in a water bath at approximately 95°C. Such methanol-soluble fraction may include PVA with a low degree of polymerization and / or a low degree of saponification. The lower limit of the proportion of methanol-soluble fraction in PVA is preferably 4% by mass, more preferably 6% by mass, and even more preferably 7% by mass. The upper limit of the proportion of methanol-soluble fraction in PVA is preferably 10% by mass, more preferably 9% by mass, and even more preferably 8% by mass. When the proportion of methanol-soluble fraction is within the above range, the seed coating material has better adhesion to the seed surface. This is thought to be because the methanol-soluble portion of the hydrophobic component of PVA is adsorbed onto the hydrophobic seed surface, improving the adhesive strength between the PVA and the seed surface.

[0012] The lower limit of the saponification degree of PVA is preferably 70.0 mol%, more preferably 72.0 mol%. The upper limit of the saponification degree of PVA is preferably 86.0 mol%, more preferably 80.0 mol%, and even more preferably 75.0 mol%. When the saponification degree of PVA is within the above range, the adhesion (coating property) to the seed surface is more excellent. The saponification degree of PVA is measured by the method described in JIS K6726:1994.

[0013] The lower limit of the viscosity-average degree of polymerization of the PVA is preferably 100, more preferably 200, even more preferably 300, and even more preferably 400. The upper limit of the viscosity-average degree of polymerization of the PVA is preferably 3500, more preferably 2000, even more preferably 1500, and even more preferably 1000. When the viscosity-average degree of polymerization of the PVA is within the above range, the adhesion (coating ability) to the seed surface is more excellent. The viscosity-average degree of polymerization of the PVA is measured in accordance with JIS K6726:1994.

[0014] PVA 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.

[0015] The PVA may be a modified PVA into which units or functional groups other than units derived from vinyl ester monomers are introduced by using techniques such as copolymerization, acetalization, and esterification.

[0016] When the PVA 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 copolymerizable 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 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 such monomers include: 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.

[0017] When the PVA 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 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. The modifying agent may also 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.

[0018] When the PVA is a modified PVA in which a modifying group has been introduced by esterification, the modifier used to introduce the modifying group by esterification is not particularly limited. Examples of the modifier 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 modifier may also 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.

[0019] In the production of PVA, 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.

[0020] 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.

[0021] 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.

[0022] 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 preferably used. The amount of the chain transfer agent can be determined to the intended degree of polymerization of the vinyl ester polymer depending on the chain transfer constant of the chain transfer agent added, within a range that does not impair the effects of the present invention. Furthermore, functional groups may be introduced using such agents, such as a chain transfer agent having an alkyl group to introduce an aliphatic hydrocarbon group at the end, or a chain transfer agent having a carboxy group to introduce an ionic functional group at the end.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] The PVA resin obtained through actual production may contain components other than PVA, such as residues of compounds used in the production process and components generated by side reactions, etc. Hereinafter, the produced PVA resin containing such components other than PVA may be referred to as "PVA resin." For example, PVA resin may contain sodium acetate in addition to PVA.

[0028] As described above, the seed coating material of the present invention may contain sodium acetate. In the seed coating material, the ratio of the total content of the methanol-soluble matter of the PVA and sodium acetate to the total content of the PVA and sodium acetate is 2% by mass or more and 20% by mass or less. The lower limit of this ratio is preferably 4% by mass, more preferably 5% by mass, even more preferably 6% by mass, and even more preferably 7% by mass. The upper limit of this ratio is preferably 15% by mass, more preferably 12% by mass, even more preferably 10% by mass, and even more preferably 9% by mass. When the ratio of the total content of the methanol-soluble matter of the PVA and sodium acetate to the total content of the PVA and sodium acetate is within the above range, the adhesion of the seed coating material to the seed surface is improved, the amount of fine powder generated is reduced, and the seed coating performance is excellent.

[0029] The seed coating material preferably contains sodium acetate. The presence of sodium acetate in the seed coating material reduces the crystallinity of PVA, resulting in a film formed from the seed coating material that is neither too rigid nor too soft, and is superior. The lower limit of the content of sodium acetate relative to the total content of PVA and sodium acetate in the seed coating material is preferably 0.1% by mass, more preferably 0.5% by mass, and even more preferably 0.8% by mass. The upper limit of the content of sodium acetate relative to the total content of PVA and sodium acetate in the seed coating material is preferably 10% by mass, more preferably 5% by mass, even more preferably 3% by mass, and even more preferably 1% by mass.

[0030] The ratio of the total content of the methanol-soluble content of PVA and sodium acetate to the total content of PVA and sodium acetate in the seed coating material can be determined from the masses of PVA, the methanol-soluble content of PVA, and sodium acetate contained in the seed coating material. Hereinafter, in this specification, the symbol "X" will be added to "the ratio of the total content of the methanol-soluble content of PVA and sodium acetate to the total content of PVA and sodium acetate," and may be referred to as, for example, "the ratio X of the total content of the methanol-soluble content and sodium acetate," "the ratio X," or simply "X."

[0031] The methanol-soluble matter and sodium acetate in the seed coating material may be components derived from the PVA resin, which is the raw material for the seed coating material, or may be components added separately from the PVA resin during the production of the seed coating material.

[0032] The masses of PVA, methanol-soluble PVA, and sodium acetate contained in the seed coating material can be measured by an appropriate method depending on the composition of the seed coating material. For example, in one embodiment, when the seed coating material is made from a PVA resin containing PVA and sodium acetate, the PVA, methanol-soluble PVA, and sodium acetate contained in the seed coating material may be derived solely from the raw PVA resin. The PVA resin may also consist essentially of PVA (including the methanol-soluble PVA) and sodium acetate. In such cases, the proportion X in the seed coating material is equal to the proportion X of the raw PVA resin. In this case, the proportion X can be measured by the following method: 10 g of PVA resin is weighed into a cylindrical filter paper, and the weighed PVA resin is washed for 8 hours using a Soxhlet washer with methanol as a washing solvent. The amount of methanol is 100 mL per 10 g of PVA resin. Washing using the Soxhlet washer is performed in a water bath at approximately 95°C. The washing solution after the washing treatment is recovered, the methanol is removed from the obtained washing solution by drying, and the mass of the obtained residue is used to calculate the proportion X according to the following formula. In this embodiment, the proportion X of the PVA resin calculated by this method is the proportion X of the seed coating material: X (mass %) = ([mass of residue (g)] / [10 (g)]) x 100

[0033] In addition, when the seed coating material contains components other than PVA (including methanol-soluble components of PVA) and sodium acetate, the ratio X can be determined, for example, by removing the other components by a known method and then performing the above measurement.

[0034] The proportion X of the seed coating material may be adjusted by adjusting the amount of methanol-soluble PVA or sodium acetate added to the seed coating material. Alternatively, the proportion X of the seed coating material may be adjusted by adjusting the proportion X of the PVA resin, which is a raw material for the seed coating material. Examples of methods for adjusting the proportion X of the PVA resin include adjusting the polymerization and / or saponification conditions in the PVA resin production process and the washing conditions for the PVA resin after saponification, i.e., adjusting the type of washing solvent, washing time, temperature, number of times, etc.

[0035] The solvent used to wash the PVA resin obtained after the saponification reaction may be methyl acetate or a mixed solution containing methyl acetate and another solvent. However, from the viewpoint of adjusting the ratio X in the PVA resin, it is preferable to use a mixed solution containing methyl acetate and another solvent. As the mixed solution, a methyl acetate / methanol mixed solution is preferred, and the mass ratio of methyl acetate / methanol is preferably 9 / 1 to 7 / 3. The temperature during washing is preferably 45 to 55°C, and the number of washings is preferably 1 to 3.

[0036] The drying temperature after washing of the PVA resin is preferably 65 to 130° C., and the drying time is preferably 3 to 12 hours.

[0037] In the seed coating material, the PVA content is preferably 2 to 10% by mass based on the total mass of the seed coating material. The content of PVA in the solid content of the seed coating material may be, for example, 30% by mass or more and 90% by mass or less, or 40% by mass or more and 60% by mass or less.

[0038] In one embodiment, the seed coating material preferably contains inorganic fine particles. The inorganic fine particles may have an average particle size (D50) of, for example, 0.1 μm to 500 μm, 0.5 μm to 200 μm, or 1 μm to 100 μm. 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.

[0039] The mass ratio of inorganic fine particles to PVA in the seed coating material 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.

[0040] The seed coating material 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.

[0041] 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).

[0042] 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.

[0043] The insecticide is preferably at least one selected from the group consisting of clothianidin, tefluthrin, terbufos, cypermethrin, thiodicarb, lindane, furathiocarb, and acephate.

[0044] In one embodiment, the seed coating material may be a solution containing a solvent. The solvent is preferably water, and the water may be ion-exchanged water. The seed coating material may be solid. In particular, the seed coating material in the state where it coats the surface of a seed (the seed coating material provided on the coated seed) is usually solid.

[0045] In one embodiment, when the seed coating material is a solution, its solids concentration is not particularly limited, but is preferably 30 to 50 mass% based on the total mass of the seed coating material. Furthermore, for example, such a seed coating material having a solids concentration of 30 to 50 mass% may be diluted with a medium such as water to any suitable concentration before use. The solids concentration of the seed coating material when used may be, for example, 1 to 10 mass%.

[0046] In one embodiment, depending on the PVA and other optional raw materials, the seed coating material may be in the form of, for example, a solution, dispersion, emulsion, suspension, etc. For example, some of the components contained in the seed coating material may be in solution, while other components may be dispersed, emulsified, and / or suspended. In such an embodiment, the components of the seed coating material are preferably substantially uniformly distributed before application to the seeds, and therefore the seed coating material is preferably a stable solution, emulsion, and / or dispersion, or a solution, emulsion, dispersion, and / or suspension, which can easily distribute the components uniformly by conventional means, such as stirring with or without gentle heating.

[0047] In one embodiment, the seed coating material may be blended with other polymers compatible with PVA, such as polyvinylpyrrolidone, starch, and 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 seed coating material in the form of a solution, dispersion, emulsion, or suspension. Furthermore, a polyhydric alcohol, such as trimethylolpropane, glycerin, or propylene glycol, may be added to enhance the adhesion of PVA to the seed surface.

[0048] The method for coating seeds with the seed coating material is not particularly limited, and for example, the seeds may be mixed with the seed coating material, or the seed coating material may be sprayed onto the seeds. The coating method may be a batch type or a continuous type coating. A coating machine may be used for coating, and examples of the coating machine include a rotary coater, a drum coater, and a dry pan type granulator. After coating the seeds with the liquid seed coating material, or simultaneously with coating, drying may be performed.

[0049] <Coated seeds> One embodiment of the present invention is coated seeds, at least a portion of the surface of which is coated with the above-mentioned seed coating material. By coating seeds with the seed coating material of the present invention, seeds with an excellent germination rate can be obtained. A preferred embodiment is coated seeds coated with a seed coating material containing a pesticide, and such coated seeds have less peeling of the pesticide from the seeds and have a better germination rate. The coverage rate of the coated seeds is preferably 80% or more, more preferably 90% or more. The coverage rate is measured by the method described in the Examples below.

[0050] 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, onions, bulbs, rice, sorghum, corn, tobacco, nuts, coffee, and sugarcane, and preferably at least one selected from the group consisting of corn, wheat, and soybeans.

[0051] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the examples, the amount of dust generation, biodegradability, coating properties, etc. were measured by the following methods.

[0052] <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, PVA-1 to PVA-4 were saponified to a degree of saponification of 99.5 mol% or more, and the viscosity average degree of polymerization of each of the saponified 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）

[0053] <Saponification Degree> The saponification degrees (mol %) of PVA-1 to PVA-4 were measured in accordance with JIS K6726:1994.

[0054] <Proportion X of the Total Content of Methanol-Soluble Matter and Sodium Acetate> 10 g of each of PVA-1 to 4 (PVA resins) obtained in each Production Example was weighed into a cylindrical filter paper and washed for 8 hours using methanol as a washing solvent in a Soxhlet washer. The amount of methanol was 100 mL per 10 g of PVA resin. Washing using the Soxhlet washer was carried out in a water bath at approximately 95°C. The washing solution after the washing treatment was recovered, and the methanol was removed from the resulting washing solution by drying. The mass of the resulting residue was used to calculate the proportion X (mass %) of the total content of the methanol-soluble matter and sodium acetate of the PVA relative to the total content of the PVA and sodium acetate according to the following formula: X (mass %) = ([mass of residue (g)] / [10 (g)]) × 100

[0055] <Proportion Y of Methanol-Soluble Content in PVA> The proportion Y (mass%) of methanol-soluble content in PVA was calculated from the mass of the residue obtained in the measurement of the proportion X and the mass of sodium acetate contained in PVA 1 to 4 according to the following formula: Y (mass%) = ([mass of residue (g) - mass of sodium acetate (g)] / [10 (g) - mass of sodium acetate (g)]) x 100

[0056] [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, Asahi Rika Seisakusho Co., Ltd.) and rotated at 80 rpm for 15 minutes. The treated coated seeds were placed on a metal sieve to remove fine powder, and the mass of the coated seeds after fine powder removal was measured using a precision balance. The mass loss before and after fine powder removal was taken as the amount of dust generated and was evaluated as A to C as follows: A: Amount of dust generated is less than 10 mg B: Amount of dust generated is 10 mg or more but less than 20 mg C: Amount of dust generated is 20 mg or more

[0057] [Biodegradability of Resin Component] For PVA-1 to 4 and the resin component Em-1 used in Comparative Examples 4 to 6, biodegradability was evaluated in accordance with ISO 14851 (BOD measurement using activated sludge), with A being assigned to samples that were decomposed by 60% or more in water within 28 days, and B being assigned to samples that were decomposed by less than 60%.

[0058] [Coating] The coverage of coated seeds was calculated using the image analysis software ImageJ according to the following procedure, and coverage was evaluated with A for a coverage of 90% or more, B for less than 90% and 80% or more, and C for less than 80%. The photograph used for image processing of the coated seeds of Example 2 is shown in Figure 1, and the photograph used for image processing of the coated seeds of Comparative Example 3 is shown in Figure 2. 1. The photograph of the coated seeds was loaded into ImageJ. 2. The uncoated area was selected using Color Threshold. Saturation was set to 0-255, Brightness: 0-255, and the hue area was adjusted from 0 to an arbitrary value, so that the uncoated area was selected as red. 3. The red component was separated using Split Channels. 4. The resulting red was used to select areas other than the white area using a threshold. The selected area was set to 0 to 254. 5. The % Area value in Measure was used as the coverage rate for evaluation.

[0059] [Production Example 1] 720 g of vinyl acetate and 880 g of methanol were charged into a 3 L reactor 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 bubbling with nitrogen for 30 minutes. The temperature inside the reactor 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 system was cooled and terminated. 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 so that the alkali molar ratio (moles of NaOH / moles of vinyl ester units in polyvinyl acetate) was 0.0037, and the resulting gel was washed at 50°C with 2 L of a methyl acetate / methanol mixture (8 / 2 by mass). After washing twice in total, the resulting resin was dried at 70°C for 12 hours to obtain PVA-1 as a PVA resin containing a vinyl alcohol polymer and sodium acetate (a PVA resin consisting essentially of a vinyl alcohol polymer and sodium acetate). Table 1 shows the degree of saponification, viscosity-average degree of polymerization, proportion Y of the methanol-soluble matter in the PVA in PVA-1, and proportion X of the total content of the methanol-soluble matter and sodium acetate to the total content of PVA and sodium acetate.

[0060] [Production Example 2] 720 g of vinyl acetate and 880 g of methanol were charged into a 3 L reactor 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 reactor 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 so that the alkali molar ratio (moles of NaOH / moles of vinyl ester units in polyvinyl acetate) was 0.0073. The resulting gel was then washed with 2 L of methanol at 50°C. After washing twice in total, the resin was dried at 70°C for 12 hours to obtain PVA-2 as a PVA resin containing a vinyl alcohol polymer and sodium acetate (a PVA resin consisting essentially of a vinyl alcohol polymer and sodium acetate). Table 1 shows the degree of saponification, viscosity-average degree of polymerization, proportion Y of the methanol-soluble matter in the PVA in PVA-2, and proportion X of the total content of the methanol-soluble matter and sodium acetate to the total content of PVA and sodium acetate.

[0061] [Production Example 3] 720 g of vinyl acetate and 880 g of methanol were charged into a 3 L reactor 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 reactor 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 so that the alkali molar ratio (moles of NaOH / moles of vinyl ester units in polyvinyl acetate) was 0.03. The resulting gel was then washed with 2 L of methanol at 50°C. After washing twice in total, the resin was dried at 70°C for 12 hours to obtain PVA-3 as a PVA resin containing a vinyl alcohol polymer and sodium acetate (a PVA resin consisting essentially of a vinyl alcohol polymer and sodium acetate). Table 1 shows the degree of saponification, viscosity-average degree of polymerization, proportion Y of the methanol-soluble matter in the PVA in PVA-3, and proportion X of the total content of the methanol-soluble matter and sodium acetate to the total content of PVA and sodium acetate.

[0062] [Production Example 4] A 3-L reaction vessel equipped with a stirrer, a nitrogen inlet, an additive inlet, and an initiator inlet was charged with 1,280 g of vinyl acetate and 320 g of methanol. 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 60%, 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 so that the alkali molar ratio (moles of NaOH / moles of vinyl ester units in polyvinyl acetate) was 0.0073. The resulting gel was then washed with 2 L of methanol at 50°C. After washing twice in total, the resulting resin was dried at 70°C for 12 hours to obtain PVA-4 as a PVA resin containing a vinyl alcohol polymer and sodium acetate (a PVA resin consisting essentially of a vinyl alcohol polymer and sodium acetate). Table 1 shows the degree of saponification, viscosity-average degree of polymerization, proportion Y of the methanol-soluble matter in the PVA in PVA-4, and proportion X of the total content of the methanol-soluble matter and sodium acetate to the total content of PVA and sodium acetate.

[0063] Example 1 A seed coating material was prepared according to the method described below using PVA-1 as the resin component and mica (MICA C-4000, manufactured by IMERYS) as the inorganic fine particles, and designated Coat-1. The ratio X of the total content of methanol-soluble matter and sodium acetate to the total content of PVA and sodium acetate in Coat-1 was the same as the ratio X in PVA-1.

[0064] (Preparation of seed coating material) 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 homogeneous to prepare a pigment dispersion. Next, 19.7 g of an 8 mass % aqueous solution of a resin component, 4.46 g of the pigment dispersion, and 20.84 g of water were mixed until homogeneous, and the resulting mixture was used as a seed coating material.

[0065] (Coating of seeds) 8 mL of the seed coating material 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.

[0066] Example 2 A seed coating material Coat-2 was obtained in the same manner as in Example 1, except that talc (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used as the inorganic fine particles. In Coat-2, the ratio X of the total content of methanol soluble matter and sodium acetate to the total content of PVA and sodium acetate was the same as the ratio X in PVA-1.

[0067] Comparative Example 1 A seed coating material Coat-3 was obtained in the same manner as in Example 1, except that PVA-2 was used as the resin component and talc (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used as the inorganic fine particles. Note that the ratio X of the total content of methanol-soluble matter and sodium acetate to the total content of PVA and sodium acetate in Coat-3 was the same as the ratio X in PVA-2.

[0068] Comparative Example 2 A seed coating material Coat-4 was obtained in the same manner as in Example 1, except that PVA-3 was used as the resin component and talc (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used as the inorganic fine particles. Note that the ratio X of the total content of methanol-soluble matter and sodium acetate to the total content of PVA and sodium acetate in Coat-4 was the same as the ratio X in PVA-3.

[0069] Comparative Example 3 A seed coating material Coat-5 was obtained in the same manner as in Example 1, except that PVA-4 was used as the resin component and talc (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used as the inorganic fine particles. Note that the ratio X of the total content of methanol-soluble matter and sodium acetate to the total content of PVA and sodium acetate in Coat-5 was the same as the ratio X in PVA-4.

[0070] Comparative Example 4 A seed coating material designated Coat-6 was prepared in the same manner as in Example 1, except that Em-1 was used as the resin component, mica (MICA C-4000, manufactured by IMERYS) was used as the inorganic fine particles, 3.3 g of polyethylene wax (trade name "Liquitron 461", manufactured by Lubrizol) was added as an additional additive, and the amount of deionized water used was changed to 17.54 g. Em-1 is a resin component having the same composition as the latex carrier described in Table 1 of Patent Document 1 (WO 2013 / 166020).

[0071] Comparative Example 5 A seed coating material Coat-7 was obtained in the same manner as in Example 1, except that Em-1 was used as the resin component.

[0072] Comparative Example 6 A seed-coating composition Coat-8 was obtained in the same manner as in Comparative Example 4, except that talc (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used as the inorganic fine particles.

[0073]

[0074]

[0075] The results of dust generation, biodegradability, and coating properties for Examples 1 and 2 and Comparative Examples 1 to 6 are summarized in Table 2. The seed coating materials of Examples 1 and 2 satisfied all of the requirements for low dust generation, biodegradability, and good coating properties. The seed coating materials of Comparative Examples 1 to 3 all had a ratio X of the total content of methanol-soluble matter and sodium acetate relative to the total content of PVA and sodium acetate of less than 2 mass%, resulting in high dust generation and / or poor coating properties. In Figure 1, which is a photograph of coated seeds from Example 2, and Figure 2, which is a photograph of coated seeds from Comparative Example 3, the darker-colored areas are the coated areas, and it can be seen that the coated seeds of Example 2 have a larger coated area than Comparative Example 3. Furthermore, the seed coating materials of Comparative Examples 4 to 6 did not contain PVA and resulted in poor biodegradability.

Claims

1. A seed coating material containing a vinyl alcohol polymer and optionally sodium acetate, wherein the ratio of the total content of the methanol-soluble portion of the vinyl alcohol polymer and the sodium acetate to the total content of the vinyl alcohol polymer and the sodium acetate is 2% by mass or more and 20% by mass or less.

2. The seed coating material according to claim 1, wherein the proportion of methanol-soluble matter in the vinyl alcohol polymer is 4% by mass or more and 10% by mass or less.

3. The seed coating material according to claim 1, wherein the degree of saponification of the vinyl alcohol polymer is 70.0 mol % or more and 86.0 mol % or less.

4. The seed coating material according to claim 1, further comprising inorganic fine particles.

5. The seed coating material 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 seed coating material according to claim 5, comprising talc as the inorganic fine particles.

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

9. The coated seed according to claim 8, wherein the seed is at least one selected from the group consisting of corn, wheat and soybean.

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