Aqueous seed coating composition

Abstract

The present invention relates to an aqueous seed coating composition. The present invention generally relates to an aqueous seed coating composition based on a specific polyvinyl alcohol copolymer resin as a binder and a hydrophobic pesticide additive, and to seeds coated with such a coating composition, said coated seeds having an ideal combination of low dusting in bulk, bulk seed flowability, and good germination characteristics.

Description

[0001] This divisional application of the present invention is a divisional application of the invention patent application with PCT patent application number PCT / US2019 / 037636, application date of June 18, 2019, and invention title of "aqueous seed coating composition". The application number of the parent case entering China is 201980041442.1. Field of the Invention

[0002] The present invention generally relates to aqueous seed coating compositions based on specific polyvinyl alcohol copolymer resins as the binder, and seeds coated with such coating compositions. The resulting coated seeds have a desirable combination of bulk low dusting, bulk seed flowability, and good germination characteristics.

[0003] In particular, the polyvinyl alcohol copolymer is selected from (a) specific highly hydrolyzed copolymers of vinyl acetate and a smaller amount of ethylene, and (b) specific highly hydrolyzed copolymers of vinyl acetate and a smaller amount of unsaturated acid comonomer components.

[0004] The seed coating composition comprises such polyvinyl alcohol copolymer in an aqueous carrier medium together with a hydrophobic "pesticide" additive and other optional additives. Background of the Invention

[0005] Seed treatment refers to applying materials to seeds to improve handling characteristics, protect seeds before germination, and support the germination process. In addition, seed treatment confers insect resistance properties to the seeds or the resulting plants by incorporating active "pesticide" ingredients such as insecticides, fungicides, and nematicides. Plant growth regulators that improve the handling characteristics of seeds can also be added to the seed coating formulation. Seed treatment eliminates or at least reduces the need for traditional spray applications of foliar fungicides or insecticides.

[0006] Unfortunately, many known seed treatments produce excessive dust during the storage and application of the seed material, which can cause bulk seeds to agglomerate and can reduce germination efficiency.

[0007] A variety of and many seed coating compositions and ingredients for improving seed handling, germination, storage, and growth properties have been disclosed in the literature. See, for example, US3698133, US3707807, US3947996, US4249343, US4272417, US4729190, US5849320, US5876739, US90101131B2, WO90 / 11011A1, WO2005 / 062899A2, WO2008 / 037489A2, WO2013 / 166020A1, and WO2017 / 187994A1.

[0008] Aqueous seed coating compositions typically comprise an aqueous medium, one or more functional additives, and a binder which, upon application and drying, forms a matrix for the various functional additives and a protective film for covering the seeds.

[0009] Some seed treatments incorporate prophylactic treatments and enhancements, such as treatments with pesticides (e.g., fungicides and / or insecticides) combined with one or more plant elicitors and / or inoculants.

[0010] As disclosed in previously incorporated references, many different materials have been used as binders in aqueous seed coating compositions.

[0011] Among the disclosed binder materials typically included are polyvinyl alcohol homopolymers, copolymers, and their functionally modified and / or crosslinked variants. See, for example, previously incorporated US3707807, US3947996, US4249343, US4272417, US5849320, US5876739, US90101131B2, and WO2017 / 187994A1.

[0012] Some commercially available polymer binders, including some polyvinyl alcohols, are plagued by low water solubility / dispersibility, low coated-seed flowability, high dust-off, and / or poor seed-applicability characteristics.

[0013] For example, seed coating additives optimized for reducing dust-off can result in poor seed flowability. This can be explained by the fact that ingredients added to increase the stickiness of the coating (and thus make it less susceptible to dusting) can result in unacceptably poor flowability and seed-applicability characteristics, as the stickiness that generally reduces dust-off creates flowability problems.

[0014] On the other hand, elements of the coating that improve seed flow characteristics have a negative impact on the dust-off properties. For mechanical seeding, the seeds must be non-agglomerated. Seeds coated with a polymer binder having insufficient hydrophobicity will stick together, especially when exposed to warm, humid air (such as that encountered in storage bins during the summer).

[0015] There is a need for a water-based, biodegradable, and cost-effective seed coating that improves long-term storage stability while maintaining or even improving the germination and seed handling properties of the seeds and provides low dust-off properties. The present invention discloses a seed treatment formulation based on certain specified polyvinyl alcohols as the binder, which provides a good combination of dust-off properties, long-term storage stability, seed flowability, seed-applicability, and germination characteristics when applied to seeds. SUMMARY OF THE INVENTION

[0016] According to the present invention, it has been found that certain specific polyvinyl alcohol copolymer bases in combination with hydrophobic pesticides in aqueous seed coating compositions provide an overall combination of desired characteristics such as dust-off characteristics, seed flowability, storage stability, and germination rate.

[0017] In a first aspect, the present invention provides a coating composition comprising a solution, dispersion, emulsion, or suspension of a polyvinyl alcohol polymer base and a hydrophobic pesticide additive in an aqueous medium, wherein:

[0018] (1) The polyvinyl alcohol base is a polyvinyl alcohol copolymer selected from:

[0019] (A) A hydrolyzed copolymer of vinyl acetate and ethylene as comonomers, having

[0020] (a) An ethylene content of from about 0.1 mole % to about 15 mole %, based on the total moles of monomers,

[0021] (b) A viscosity-average degree of polymerization of from about 300 to about 3000, and

[0022] (c) A degree of hydrolysis of from about 85 mole % to 100 mole %; and

[0023] (B) A hydrolyzed copolymer of vinyl acetate and one or more unsaturated acids as comonomers, wherein

[0024] (a) The unsaturated acid is selected from

[0025] (i) Unsaturated monocarboxylic acids,

[0026] (ii) Unsaturated dicarboxylic acids,

[0027] (iii) Alkyl esters of (i),

[0028] (iv) Alkyl esters of (ii),

[0029] (v) Alkali metal salts of (i),

[0030] (vi) Alkali metal salts of (ii),

[0031] (vii) Alkaline earth metal salts of (i),

[0032] (viii) Alkaline earth metal salts of (ii), and

[0033] (ix) Anhydrides of (i) and

[0034] (x) Anhydrides of (ii), and

[0035] (b) The copolymer has

[0036] (i) An unsaturated acid content of from about 0.1 mol% to about 15 mol% based on the total moles of monomers,

[0037] (ii) A viscosity-average degree of polymerization of from about 300 to about 3000,

[0038] (iii) A degree of hydrolysis of from about 70 mol% to 100 mol%;

[0039] and

[0040] (2) The coating composition comprises from about 0.5 wt% to about 10 wt% of a polyvinyl alcohol base based on the total weight of the coating composition.

[0041] In a second aspect, the present invention provides a seed encapsulated by a film of a polyvinyl alcohol base and a hydrophobic pesticide additive, wherein the polyvinyl alcohol base is a polyvinyl alcohol copolymer selected from:

[0042] (A) A hydrolyzed copolymer of vinyl acetate and ethylene as comonomers, having

[0043] (a) An ethylene content of from about 0.1 mol% to about 15 mol% based on the total moles of monomers,

[0044] (b) A viscosity-average degree of polymerization of from about 300 to about 3000, and

[0045] (c) A degree of hydrolysis of from about 85 mol% to 100 mol%; and

[0046] (B) A hydrolyzed copolymer of vinyl acetate and one or more unsaturated acids as comonomers, wherein

[0047] (a) The unsaturated acid is selected from

[0048] (i) Unsaturated monocarboxylic acids,

[0049] (ii) Unsaturated dicarboxylic acids,

[0050] (iii) Alkyl esters of (i),

[0051] (iv) Alkyl esters of (ii),

[0052] (v) Alkali metal salts of (i),

[0053] (vi) Alkali metal salts of (ii),

[0054] (vii) Alkaline earth metal salts of (i),

[0055] (viii) Alkaline earth metal salts of (ii), and

[0056] (ix) Anhydrides of (i) and

[0057] (x) The anhydride of (ii),

[0058] (b) The copolymer has

[0059] (i) Based on the total moles of monomers, an unsaturated acid content of from about 0.1 mole % to about 15 mole %,

[0060] (ii) A viscosity-average degree of polymerization of from about 300 to about 3000, and

[0061] (iii) A degree of hydrolysis of from about 70 mole % to 100 mole %.

[0062] In a third aspect, the present invention provides seeds obtained by applying the coating composition as described above to seeds and drying the thus-applied coating.

[0063] In a fourth aspect, the present invention provides a plurality of seeds as described above having an average dust-off property of less than about 0.1 g / 100,000 seeds.

[0064] In one embodiment, the coating composition further comprises starch.

[0065] Those of ordinary skill in the art will more readily understand these and other embodiments, features and advantages of the present invention after reading the following detailed description. Detailed Description

[0066] The present invention relates to aqueous seed coating compositions, seeds coated with such coating compositions of polyvinyl alcohol products, and a plurality of such seeds having specific bulk dust-off properties. Further details are provided below.

[0067] In the context of this specification, all publications, patent applications, patents and other references (for various purposes) mentioned herein are incorporated by reference in their entirety as if fully set forth, unless otherwise specified.

[0068] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. In case of conflict, the present specification (including definitions) will control.

[0069] Trademarks are shown in capital letters unless otherwise indicated.

[0070] Unless otherwise stated, all percentages, parts, ratios, etc. are by weight.

[0071] Unless otherwise stated, the pressure expressed in psi is gauge pressure, and the pressure expressed in kPa is absolute pressure. However, the pressure difference is expressed as absolute pressure (e.g., pressure 1 is 25 psi higher than pressure 2).

[0072] When an equivalent, concentration, or other value or parameter is given as a range or a series of upper and lower limit values, this is to be understood as explicitly disclosing all ranges formed by any pair of any higher and lower range limits, whether or not these ranges are separately disclosed. When listing a numerical range herein, unless otherwise specified, the range is intended to include its endpoints and all integers and fractions within the range. It is not intended to limit the scope of the present disclosure to the specific numerical values recited when defining a range.

[0073] When the term "about" is used to describe a numerical value or the endpoint of a range, the present disclosure is to be understood as including the specific numerical value or endpoint mentioned.

[0074] As used herein, the terms "comprising", "including", "covering", "containing", "having", "owning", or any other variants thereof are intended to cover non-exclusive inclusion. For example, a process, method, article, or apparatus comprising a series of elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0075] The connecting word "consisting of" excludes any element, step, or ingredient not stated in the claim, so that the claim does not include materials other than those recited, except for impurities ordinarily associated therewith. When the phrase "consisting of" appears in a clause of the claim body rather than immediately following the preamble, it only limits the elements recited in that clause; it does not exclude other elements from the claim as a whole.

[0076] The connecting word "consisting essentially of" limits the scope of the claim to the specific materials or steps and those that do not materially affect one or more of the basic and novel characteristics of the claimed invention. A "consisting essentially of" claim is in the intermediate ground between a closed claim expressed in the form of "consisting of" and a fully open claim expressed in the form of "comprising". The term "consisting essentially of" does not exclude optional additives (at concentrations suitable for such additives) and minor impurities as defined herein from the composition.

[0077] In addition, unless expressly provided to the contrary, "or" and "and / or" are meant to be inclusive and not exclusive. For example, any one of the following satisfies condition A or B, or A and / or B: A is true (or present) and B is false (or absent), A is false (or absent) and B is true (or present), and both A and B are true (or present).

[0078] As used herein, the use of "a" or "an" to describe various elements and components is for convenience only and to give a general meaning of the disclosure. Such description shall be construed to include one or at least one, and the singular also includes the plural, unless it is clearly otherwise meant.

[0079] Unless otherwise specified herein, as used herein, the term "major portion" means greater than 50% of the material. If not specified, percentages are based on moles when referring to molecules (such as hydrogen, methane, carbon dioxide, carbon monoxide, and hydrogen sulfide), and otherwise based on weight (such as for carbon content).

[0080] Unless otherwise specified, as used herein, the term "substantial portion" or "substantially" means all or almost all or a vast majority, as would be understood by one of ordinary skill in the art in the context used. It is intended to account for a certain reasonable difference from 100% that would typically occur in industrial-scale or commercial-scale situations.

[0081] The terms "depleted" or "reduced" are equivalent to a reduction from the original presence. For example, removing a substantial portion of a material from a stream will result in a depleted stream that excludes that material to a large extent. Conversely, the terms "enriched" or "increased" are equivalent to greater than the original presence.

[0082] As used herein, the term "copolymer" refers to a polymer containing copolymer units produced by the copolymerization of two or more comonomers. In this regard, a copolymer may be described herein with reference to its constituent comonomers or the amounts of its constituent comonomers, such as "a copolymer containing vinyl acetate and 15 mole % of a comonomer", or similar descriptions. Such a description may be considered informal because its comonomers do not refer to copolymer units; because it does not include the conventional nomenclature for copolymers, such as the International Union of Pure and Applied Chemistry (IUPAC) nomenclature; because it does not use the product-by-process term; or for another reason. However, as used herein, describing a copolymer with reference to its constituent comonomers or the amounts of its constituent comonomers means that the copolymer contains copolymer units of the specific comonomers (in the specified amounts when specified). It is thus presumed that a copolymer is not the product of a reaction mixture containing a given amount of a given comonomer, unless it is explicitly stated to be so in limited circumstances.

[0083] The term "unit" refers to a unit operation. Unless otherwise specified, when more than one "unit" is described, those units operate in parallel. However, a single "unit" may, depending on the context, include more than one unit in series or in parallel. For example, a heat treatment unit may include a first cooling unit and a second cooling unit in series following it.

[0084] As used herein, the term "free-flowing" particles (or agglomerates or seeds) means (as will be well understood by one of ordinary skill in the relevant art) that the particles do not significantly further agglomerate (e.g., there is substantially no further aggregation, caking, or clumping). Free-flowing particles do not need to be "dry", but desirably, the water content of the particles is substantially internally contained, so there is very little (or no) surface moisture.

[0085] The term "solids content" refers to the material remaining after water is removed from an aqueous coating composition.

[0086] For convenience, many elements of the present invention are separately described, and lists of options and numerical ranges are provided; however, for the present disclosure, this should not be considered to limit the scope of the present disclosure or the support of any claim of the present disclosure for any such separate components, list items, or combinations of ranges. Unless otherwise specified, each and every possible combination should be considered to be explicitly disclosed for all purposes.

[0087] Although methods and materials similar or equivalent to those described herein may be used in the practice or testing of the present disclosure, suitable methods and materials are described herein. The materials, methods, and examples herein are thus for illustrative purposes only and are not intended to be limiting unless explicitly stated.

[0088] Polyvinyl alcohol copolymer

[0089] Polyvinyl alcohol homopolymers and copolymers are generally known polymers and are usually available in many forms for various end uses.

[0090] Polyvinyl alcohol cannot be easily produced directly from vinyl alcohol. Instead, on a commercial scale, polyvinyl acetate is produced by polymerizing vinyl acetate (with optional comonomers), and then the acetate groups are hydrolyzed to hydroxyl groups to varying degrees to produce polyvinyl alcohol. Several different hydrolysis methods are known and can be used for this purpose.

[0091] Polyvinyl alcohols suitable for the present invention can be classified into two broad categories:

[0092] (1) A hydrolyzed copolymer of vinyl acetate and ethylene as comonomers, wherein the copolymer has (a) an ethylene content of from about 0.1 mol% to about 15 mol% based on the total moles of monomers, (b) a viscosity-average degree of polymerization of from about 300 to about 3000, and (c) a degree of hydrolysis of from about 85 mol% to 100 mol%; and

[0093] (2) A hydrolyzed copolymer of vinyl acetate and one or more specific unsaturated acids as comonomers, wherein the copolymer has (i) an unsaturated acid monomer content of from about 0.1 mol% to about 15 mol% based on the total moles of monomers, (ii) a viscosity-average degree of polymerization of from about 300 to about 3000, and (iii) a degree of hydrolysis of from about 70 mol% to 100 mol%.

[0094] Polyvinyl alcohol copolymer (1)

[0095] Polyvinyl alcohol copolymer (1) is a hydrolyzed vinyl acetate / ethylene copolymer which is more hydrophobic (compared to polyvinyl alcohol homopolymers having a similar degree of hydrolysis and degree of polymerization) but has certain warm water (35 °C) soluble characteristics.

[0096] The polyvinyl acetate copolymer raw material for polyvinyl alcohol copolymer (1) is usually produced by free radical polymerization of vinyl acetate monomer with a smaller amount of ethylene as a comonomer in the presence of a polymerization catalyst.

[0097] The solvent commonly used in the commercial polymerization of vinyl acetate is methanol. The polymerization is usually carried out in the temperature range of 10 °C to 80 °C. The lower end of the known polymerization range gives a product with improved properties. The % conversion of vinyl acetate can vary within a wide range. Although a conversion of 20% to 100% has been found to be satisfactory, a conversion of at least about 30% is commercially preferred.

[0098] The ethylene content range of the polyvinyl acetate copolymer (and the resulting polyvinyl alcohol copolymer (1)) is from about 0.1 mol%, or from about 0.5 mol%, or from about 1.0 mol%, or from about 2.5 mol%, to about 15 mol%, or to about 10 mol%, or to about 8 mol% based on the total moles of monomers.

[0099] The viscosity-average degree of polymerization of the polyvinyl acetate copolymer (and the resulting polyvinyl alcohol copolymer (1)) varies from about 300, or from about 500, or from about 700, to about 3000, or to about 2000. The viscosity-average degree of polymerization of the polyvinyl alcohol copolymer is a value measured according to JIS K6726 (1994). Specifically, the polyvinyl alcohol copolymer is re-saponified to a degree of hydrolysis of 99.5 mol% or more, and purified, and then its viscosity-average degree of polymerization can be calculated from its intrinsic viscosity [η] (1 / g) measured in water at 30 °C using the following formula (I):

[0100] P = ([η] × 10000 / 8.29) (1 / 0.62) (I)

[0101] Polyvinyl acetate is converted to polyvinyl alcohol by hydrolysis or alcoholysis methods generally known to those of ordinary skill in the relevant art. In such methods, polyvinyl acetate is contacted with a base catalyst such as sodium hydroxide or sodium methoxide. The main products of this reaction are polyvinyl alcohol and methyl acetate.

[0102] For the polyvinyl alcohol copolymer (1), the degree of hydrolysis ranges from about 85%, or from about 90 mol%, or from about 97 mol%, to 100 mol% (maximum). The degree of hydrolysis can be measured according to JIS K6726 (1994).

[0103] Polyvinyl alcohol copolymer (2)

[0104] The polyvinyl alcohol copolymer (2) is a hydrolyzed acid-functional polyvinyl acetate copolymer.

[0105] Polyvinyl acetate copolymer raw materials are generally produced by free radical polymerization of vinyl acetate monomer with one or more "acid-functional" comonomers in the presence of a polymerization catalyst. The solvent commonly used in the commercial polymerization of vinyl acetate is methanol. The polymerization is generally carried out in the temperature range of 10 °C to 80 °C. The lower end of the known polymerization range gives products with improved properties. The % conversion of vinyl acetate to polyvinyl acetate can vary over a wide range. Although a conversion of 20% to 100% has been found to be satisfactory, a conversion of at least about 30% is preferably in commerce.

[0106] The "acid-functional" comonomer is one or more of the following: (i) an unsaturated monocarboxylic acid, (ii) an unsaturated dicarboxylic acid, (iii) an alkyl ester of (i), (iv) an alkyl ester of (ii), (v) an alkali metal salt of (i), (vi) an alkali metal salt of (ii), (vii) an alkaline earth metal salt of (i), (viii) an alkaline earth metal salt of (ii), (ix) an anhydride of (i), and (x) an anhydride of (ii).

[0107] Some examples of such comonomers include methacrylic acid, methyl methacrylate, 2-hydroxyethyl acrylate, hydroxyl methacrylate, ethyl methacrylate, n-butyl methacrylate, maleic acid, monomethyl maleate, dimethyl maleate, maleic anhydride, itaconic acid, monomethyl itaconate, dimethyl itaconate, and itaconic anhydride.

[0108] Preferred are acrylates and methacrylates of lower alkyl (C1-C8 or C1-C4). Non-limiting examples of such comonomers include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, isopropyl acrylate, isopropyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isobutyl acrylate, isobutyl methacrylate, n-butyl acrylate, n-butyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate and others. Preferred comonomers include methyl acrylate, methyl methacrylate and mixtures thereof, and especially methyl acrylate.

[0109] The comonomer content of the polyvinyl acetate copolymer (and the resulting polyvinyl alcohol copolymer (2)) ranges from about 0.1 mol%, or about 0.5 mol%, or about 1 mol%, to about 15 mol%, or to about 10 mol%, or to about 8 mol%. In the case of methyl acrylate, the amount is usually about 10 mol% or less based on the total moles of monomers. In the case of methyl methacrylate, the amount is usually about 5 mol% or less based on the total moles of monomers.

[0110] The viscosity-average degree of polymerization of the polyvinyl acetate copolymer (and the resulting polyvinyl alcohol copolymer (2)) varies from about 300, or from about 500, or from about 700, to about 3000, or to about 2000. The viscosity-average degree of polymerization of the polyvinyl alcohol copolymer is the value measured according to JIS K6726 (1994) as described above.

[0111] The polyvinyl acetate is converted to polyvinyl alcohol by hydrolysis or alcoholysis methods generally known to those of ordinary skill in the relevant art. In such methods, the polyvinyl acetate is contacted with a base catalyst such as sodium hydroxide or sodium methoxide. The main products of this reaction are polyvinyl alcohol and methyl acetate.

[0112] The resulting polyvinyl alcohol will of course have substantially the same monomer composition and degree of polymerization as the starting polyvinyl acetate.

[0113] The polyvinyl alcohol copolymer (2) should have a degree of hydrolysis ranging from about 70 mol%, or from about 75 mol%, or from about 85 mol%, or from about 93 mol%, or from about 95 mol%, or from about 98 mol%, or from about 99 mol%, to 100 mol% (maximum). The degree of hydrolysis can be measured according to JIS K6726 (1994).

[0114] For polyvinyl alcohol copolymers (2) having good cold water solubility, a slurry alcoholysis process as described in US2019 / 0055326A1 is desirably used to hydrolyze polyvinyl acetate copolymers into polyvinyl alcohol copolymers (2), since the slurry alcohol process produces polyvinyl alcohol copolymers having suitable cold water (20 °C) solubility. Such a process produces polyvinyl alcohol copolymer agglomerate particles having a "popcorn-like" morphology as discussed in the incorporated disclosure above.

[0115] As described in the incorporated disclosure above, suitable polyvinyl alcohol can be produced by a slurry alcoholysis process, in which the polyvinyl alcohol is obtained from polyvinyl acetate and recovered as a slurry in a methanol and methyl acetate solvent system. Such a process is desirably continuous. The slurry alcoholysis process is generally known to those of ordinary skill in the art, as disclosed in US2734048, but is modified as discussed in the previously incorporated US2019 / 0055326A1 and as discussed below.

[0116] In one embodiment, a first solution of typically about 30 wt% to about 60 wt% polyvinyl acetate copolymer in methanol and a second solution of a diluted sodium methoxide alcoholysis catalyst in methanol are continuously fed into an alcoholysis unit, in which a reaction takes place to produce a first slurry of alcoholyzed polyvinyl acetate (polyvinyl alcohol) and methyl acetate.

[0117] The amount of catalyst typically ranges from about 0.2 wt% to about 0.5 wt% based on the weight of the reaction mixture.

[0118] The temperature of the alcoholysis reaction in the alcoholysis unit typically ranges from about 58 °C, or from about 64 °C, to about 70 °C, or to about 68 °C. The pressure within the alcoholysis unit ranges from slightly below atmospheric pressure to slightly above atmospheric pressure, but is typically slightly above atmospheric pressure.

[0119] The alcoholysis unit contains agitation means such that the alcoholysis takes place at least in part under agitated conditions. Such agitation means are known to those of ordinary skill in the art.

[0120] When the alcoholysis reaches about 40 - 50%, part of the polymer precipitates. The insoluble material presents in the form of a gel of polymer molecules solvated with methanol. As further alcoholysis reduces solubility, the gel becomes more tenacious and begins to expel the associated solvent molecules. When the alcoholysis is complete, the polymer and the solvent are immiscible. If this gel is left undisturbed, the alcoholysis continues and the product is obtained in a large, difficult - to - process form. However, if the gel is mechanically processed (stirred) during this range of alcoholysis above about 40%, the polymer will break down into fine, alcohol - insoluble solids. The collapsed gel traps and binds to fine particles from a previous alcoholysis cycle, producing the desired "popcorn ball" morphology of polyvinyl alcohol.

[0121] In one embodiment, the alcoholysis unit consists of a main alcoholysis vessel in which the reaction takes place to produce a slurry of partially alcoholyzed polyvinyl acetate. The slurry from the main alcoholysis vessel overflows into an agitated hold vessel, which provides additional residence time to complete the alcoholysis reaction. Then the slurry from the agitated hold vessel is pumped through one or more finisher units to react the short - circuited polyvinyl acetate, thereby ensuring that the conversion rate is increased to the desired 99.5% or higher.

[0122] The preferred conversion rate is the degree of hydrolysis listed above.

[0123] Then the resulting first polyvinyl alcohol slurry can optionally be fed with an acid into a neutralization unit to neutralize less than a major portion (less than 50 equivalent %), or less than 25 equivalent %, or less than 10 equivalent %, or less than 5 equivalent % of any excess base catalyst, and a second slurry is produced. Generally, the acid used is acetic acid. The temperature entering the neutralization unit is slightly lower than in the alcoholysis unit, typically in the range of about 53°C to about 60°C, and generally in the range of about 55°C to about 58°C. The pressure conditions in the neutralization unit are generally similar to those in the alcoholysis unit.

[0124] If present, the neutralization unit can be used to control the pH of the resulting second slurry.

[0125] Desirably, there is no neutralization unit (or if present, it is bypassed, or it is present with substantially no acid feed, or it is present with no acid feed), and the excess base catalyst is substantially un - neutralized (or un - neutralized) and remains in the first slurry.

[0126] In one embodiment, if a neutralization unit is present, the second slurry from the neutralization unit, or if no neutralization unit is present, the first slurry, is subsequently fed to an optional heat treatment unit. The temperature of the first slurry or (if present) the second slurry is reduced in the heat treatment unit to a temperature lower than the temperature at which it enters the heat treatment unit. Depending on the desired morphology of the final polyvinyl alcohol copolymer particles, the temperature can be reduced to less than 50 °C, or less than 40 °C, or less than 35 °C, or less than 30 °C, or less than 25 °C, or less than the ambient conditions, with lower temperatures resulting in higher amorphous content and lower crystalline content.

[0127] The heat treatment unit can be a holding tank that has mild heating or no heating or even active cooling to reduce the temperature of the slurry between the inlet and the outlet.

[0128] In one embodiment, there is no heat treatment unit.

[0129] In one embodiment, the heat-treated slurry, or (if no heat treatment unit is present or utilized) the second slurry, or (if no heat treatment unit and no neutralization unit are present or utilized) the first slurry, is fed to a solid-liquid separation unit where polyvinyl alcohol is separated from the slurry to produce a polyvinyl alcohol wet filter cake and separated liquid. The solid-liquid separation unit can be a centrifuge and / or a filtration device or other conventional solid-liquid separation devices.

[0130] In an alternative embodiment, the heat treatment unit and the solid-liquid separation unit can be combined in a single unit operation where the residence time of the slurry and the solids is sufficient to reduce the temperature of the second slurry to the desired level.

[0131] In one embodiment, the method further comprises the step of washing the polyvinyl alcohol wet filter cake to produce a purified polyvinyl alcohol wet filter cake, and then subjecting it to a drying step. The resulting polyvinyl alcohol wet filter cake can be purified optionally by feeding the wet filter cake to a washing unit where it is typically contacted with a fresh or recycled methanol stream to remove ash components and other contaminants, thereby producing a purified polyvinyl alcohol wet filter cake.

[0132] To produce the final particle-agglomerated polyvinyl alcohol particles, the centrifuged purified polyvinyl alcohol wet filter cake, or (if no washing unit is present or utilized) the wet filter cake, is fed to a drying unit where it is dried in a conventional manner to remove sufficient residual liquid content so that the resulting particle-agglomerated polyvinyl alcohol copolymer particles can be preferably recovered as a free-flowing powder.

[0133] The D(90) particle size range of the polyvinyl alcohol copolymer agglomerated particles made by the above slurry alcoholysis method is from about 1 μm, or from about 10 μm, to about 1000 μm, or to about 400 μm.

[0134] The bulk density of the polyvinyl alcohol copolymer agglomerated particles prepared by the above slurry alcoholysis method is preferably 0.55 g / cm 3 or less, and more preferably about 0.50 g / cm 3 or less.

[0135] Additional method details can be obtained by referring to US2019 / 0055326A1 incorporated previously, as well as US2734048, US3497487, US3654247, and the common knowledge of those of ordinary skill in the relevant art.

[0136] Pesticide

[0137] The seed coating composition further comprises one or more hydrophobic pesticides. In the context of the present invention, "pesticide" is used broadly to refer to agents such as insecticides, fungicides, nematicides, and similar materials that prevent or mitigate damage to seeds by living organisms.

[0138] In the context of the present invention, a "hydrophobic" pesticide additive is a pesticide additive that is not soluble or not stably dispersed in water by itself (e.g., without the use of a surfactant).

[0139] Such hydrophobic pesticides are generally known to those of ordinary skill in the relevant art and are generally commercially available.

[0140] Examples of suitable fungicides include pyraclostrobin, fluxapyroxad, ipconazole, triflozystrobin, metalaxyl (metalaxyl 265ST), fludioxonil (fludioxonil 4L ST), thiabendazole (thiabendazole 4L ST), itriticonazole, imidacloprid, tefluthrin, and combinations thereof.

[0141] Examples of suitable insecticides include clothianidin, imidacloprid, 600ST (Nufarm US), tefluthrin, terbufos, cypermethrin, thiodicarb, lindane, furathiocarb, acephate, and combinations thereof.

[0142] Hydrophobic pesticides are generally used in a relatively small amount (an "effective amount" to achieve the desired insecticidal effect) according to the manufacturer's recommended dosage for such pesticides.

[0143] Aqueous coating composition

[0144] The aqueous coating composition contains water as the main carrier medium.

[0145] The polyvinyl alcohol copolymer is used in the aqueous coating composition in an amount of from about 0.5 wt%, or from about 1.0 wt%, or from about 2.0 wt%, to about 10 wt%, or to about 8 wt%, or to about 6 wt% based on the total weight of the coating composition.

[0146] Depending on the optional components described below, the solids content of the aqueous coating composition according to the present invention will generally range from about 1 wt%, or from about 2 wt%, or from about 5 wt%, to about 25 wt%, or to about 20 wt% based on the total weight of the aqueous coating composition.

[0147] The aqueous coating composition can also be provided as a concentrate, which can be diluted with water and then applied to the seeds.

[0148] Depending on the polyvinyl alcohol copolymer and other optional ingredients, the aqueous coating composition can be in the form of a solution, dispersion, emulsion or suspension, as understood by those of ordinary skill in the art. For example, some components can be in solution while others can be dispersed, emulsified and / or suspended. In such cases, the components of the aqueous coating composition should be substantially uniformly distributed in the aqueous coating before application. Thus, the aqueous coating composition should desirably be a stable solution, emulsion and / or dispersion, or a solution, emulsion, dispersion and / or suspension in which the components can be easily uniformly distributed by conventional means such as stirring with or without gentle heating.

[0149] Optional component

[0150] Other polymers compatible with polyvinyl alcohol, such as polyvinylpyrrolidone, starch and high molecular weight polyethylene glycol, can be blended into the polyvinyl alcohol to enhance the coating properties. Plasticizers, talc, pigments and anti-sticking agents can be optionally added to the seed coating solution, emulsion or suspension.

[0151] Application of the aqueous coating composition

[0152] The method of applying the aqueous coating composition to the seeds is well known to those skilled in the art. Conventional methods include, for example, mixing, spraying or a combination thereof. Various coating machines using various coating techniques are available for purchase, such as rotary coating machines, drum coating machines and fluidized beds. The seeds can be coated by batch or continuous coating methods.

[0153] The seeds are desirably coated substantially uniformly with the film of the coating composition.

[0154] Coated seeds

[0155] Seeds to be treated with the seed coating compositions described herein include, for example, wheat, barley, rye, oats, rice, sorghum, apples, pears, plums, peaches, almonds, cherries, strawberries, raspberries, blackberries, sugar beets, fodder beets, legumes, lentils, peas, soybeans, rapeseed, mustard, poppy, olives, sunflowers, coconuts, castor beans, cocoa beans, zucchini, cucumbers, melons, cotton, flax, hemp, jute, oranges, lemons, grapefruits, citrus fruits, spinach, lettuce, asparagus, cabbages, carrots, onions, tomatoes, potatoes, red peppers, avocados, flowers, shrubs, broad-leaved trees, coniferous trees, soybeans, beans, tomatoes, peppers, potatoes, grains (corn), onions, bulbs, rice, sorghum, maize, tobacco, nuts, coffee, and sugar cane. Examples

[0156] The present invention will be further understood from the following specific examples of a polymeric nature. However, it is to be understood that these examples should not be taken as limiting the general scope of the invention in any way.

[0157] CPVOH #1 is a partially hydrolyzed (87 - 89 mol%) and medium viscosity (20.5 - 24.5 mPa·s) polyvinyl alcohol homopolymer that can be purchased from Kuraray Co., Ltd. (Tokyo, Japan) under the trade name “KURARAY POVAL TM 22 - 88”.

[0158] CPVOH #2 is a partially hydrolyzed (86.5 - 90 mol%) and lower viscosity (4.6 - 5.4 mPa·s) polyvinyl alcohol homopolymer that can be purchased from Kuraray Co., Ltd. (Tokyo, Japan) under the trade name “KURARAY POVAL TM 5 - 88”.

[0159] PVOH 1 - 1 is an ethylene - vinyl alcohol copolymer that is highly hydrolyzed (98.2 mol%), has a medium viscosity - average degree of polymerization (1550), and an ethylene content of 4.1 mol%, obtained by hydrolyzing a copolymer of ethylene and vinyl acetate.

[0160] PVOH 2 - 1 is a methyl acrylate - vinyl alcohol copolymer that is highly hydrolyzed (99.5 mol%), has a medium viscosity - average degree of polymerization (1440), and a methyl acrylate content of 5.1 mol%, obtained by hydrolyzing a copolymer of methyl acrylate and vinyl acetate.

[0161] Example 1: Treatment of soybean seeds

[0162] Prepare the seed coating formulations according to Table 2. With A base treatment of soybean seeds with a package (Monsanto Company, containing metalaxyl, pyraclostrobin, imidacloprid, and fluxapyroxad), Color Coat Red, and water is carried out to achieve a rate of 5.8 fl.oz / cwt of the package.

[0163] Table 2

[0164]

[0165] Dust-off procedure: The dry treated soybean seeds are tumbled under vacuum in a closed system. An air stream passing through the container is maintained and filtered through a screen. The amount of dust on the filter is weighed and the results are shown in Table 3 below.

[0166] Table 3

[0167] PVOH Coating formulation Average grams of dust / 100,000 seeds Control #1 0.0130 PVOH 1-1 #1 0.0069 PVOH 1-1 #2 0.0060 CPVOH#1 #1 0.0078 CPVOH#2 #1 0.0190 PVOH 2-1 #1 0.0060 。

[0168] It can be seen that both PVOH types (1) and (2) exhibit lower dust generation than the control (without PVOH) or the coating using the standard polyvinyl alcohol homopolymer (CPVOH).

[0169] Warm germination: This test is used to determine the maximum germination potential of untreated and treated seeds. 100 seeds are planted on moist crepe cellulose paper and placed at 25 °C for 7 days, repeated 4 times, and thereafter the seedlings are evaluated as "normal", "abnormal", or "dead" according to AOSA rules. The average percentage of "normal" germination is determined by subtracting any "abnormal" or "dead" seeds from the seeds germinated during the test period, dividing by the total number of original seeds, and multiplying by 100. The results are shown in Table 4 below.

[0170] Table 4

[0171] PVOH Coating Normal Abnormal Dead None Control 95 4 0 PVOH 1-1 Coating #1 96 4 0 PVOH 1-1 Coating #2 95 4 1 。

[0172] Since the warm germination test represents ideal and non-stressed germination conditions, the results indicate that the coating composition of the present invention has no harmful effect on the germination rate under ideal conditions. Therefore, these results show that the coating composition of the present invention does not impair or reduce the germination of seeds compared to the control seeds required to determine an effective seed coating.

[0173] Cold germination test: This test was designed to measure the ability of seeds to germinate under adverse conditions of high soil moisture, low soil temperature, and microbial activity. Four replicates of 100 seeds were planted on moist crumpled cellulose paper and covered with sand. The covered trays were placed at 10 °C for 7 days and transferred to 25 °C for 4 days, after which the seedlings were evaluated as "normal" according to AOSA rules with reference to the growth vigor. The number of seeds germinated during the test period minus any "abnormal" or "dead" seeds, divided by the total number of original seeds, and multiplied by 100, the average was determined as the "normal" germination percentage. The results are shown in Table 5 below.

[0174] Table 5

[0175] PVOH Coating Normal None Control 78 PVOH 1-1 Coating #1 84 PVOH 1-1 Coating #2 87 。

[0176] The results of the cold germination test showed a significant improvement in the germination percentage of the seeds coated with the coating composition according to the present invention.

[0177] Accelerated aging test: The accelerated aging test evaluates the carryover potential of a seed lot during storage in a warehouse. The seeds were weighed and placed in a water-jacketed chamber and maintained at 43 °C and high humidity for 72 hours. Four replicates of 100 seeds were planted on moist crumpled cellulose paper and covered with sand. The planted covered trays were placed at 25 °C for 7 days, after which the normal seedlings were evaluated according to AOSA rules. The number of seeds germinated during the test period minus any "abnormal" or "dead" seeds, divided by the total number of original seeds, and multiplied by 100, the average was determined as the "normal" germination percentage. The results are shown in Table 6 below.

[0178] Table 6

[0179] PVOH Coating Normal None Control 71 PVOH 1-1 Coating #1 70 PVOH 1-1 Coating #2 79 。

[0180] The results of the accelerated aging showed at least no material degradation of the uncoated seeds compared to the control. Therefore, these results indicate that the coating composition of the present invention does not impair or reduce the germination of the seeds compared to the control seeds required for determining an effective seed coating.

[0181] Flowability: The time taken for 1200 grams (300 grams in four replicates) of seeds to flow through a funnel at 56% relative humidity and 25 °C was measured as the dry flow of soybeans. Adding a coating to soybeans tended to significantly slow down the flow of the seeds, which is not a desirable characteristic. As shown in Table 7, the use of the coating composition according to the present invention slowed down the flow by less than one second compared to the control and actually flowed as fast as the untreated seeds.

[0182] Seeding bridging occurs when the seeds exiting the coating machine are collected in a storage hopper and compacted by the seeds arriving subsequently. This poses challenges to the seed processing facility in terms of equipment blockage, labor, and time. As shown in Table 7, the use of the coating composition according to the present invention does not exhibit a tendency to bridge.

[0183] Table 7

[0184] PVOH Coating Average Note None Control 2.20 No bridging was observed PVOH 1-1 Coating #1 2.41 No bridging was observed PVOH 1-1 Coating #2 2.23 No bridging was observed 。

[0185] Suitability for seeding: Establish the correct seeding distance, where the seeding distance between seeds is + / - 25% of the target distance. Evaluate the expected targets where single seeds should be sown: In the case of a missing single seed, it is counted as a missing target (calculated as a percentage of the total number of targets), and in the case of two or more consecutive missing targets, they are counted as multiple missing targets. The number of seeds used in each trial is 1000. Table 8 shows that the seeds treated according to the present invention exhibit better suitability for seeding than the control. Obviously, the increased seeding rate and the lower incidence of repeated seeds or completely missing targets in a single target will result in a more uniform plant population, which contributes to better growth conditions and ultimately increases the yield per unit of planted area.

[0186] Table 8

[0187]

Claims

1. A seed coating composition comprising a solution, dispersion, emulsion or suspension in water of a polyvinyl alcohol polymer base and a hydrophobic pesticide additive, characterized in that: (1) The polyvinyl alcohol is: (A) A hydrolyzed copolymer of vinyl acetate and ethylene as comonomers, having (a) An ethylene content of 0.1 mol% to less than 10 mol% based on the total moles of monomers, (b) A viscosity-average degree of polymerization of 300 to 3000, which is measured according to JIS K6726 (1994), and (c) A degree of hydrolysis of 85 mol% to 100 mol%; and (2) The coating composition comprises 0.5 wt% to 10 wt% of polyvinyl alcohol based on the total weight of the coating composition, The coating composition comprises at least one hydrophobic pesticide additive selected from fungicides, insecticides and nematicides.

2. A method for encapsulating seeds with a film of polyvinyl alcohol, characterized in that The polyvinyl alcohol is (A) a hydrolyzed copolymer of vinyl acetate and ethylene as comonomers, having (a) An ethylene content of 0.1 mol% to less than 10 mol% based on the total moles of monomers, (b) A viscosity-average degree of polymerization of 300 to 3000, which is measured according to JIS K6726 (1994), and (c) A degree of hydrolysis of 85 mol% to 100 mol%; wherein the film further comprises a hydrophobic pesticide additive, and the seeds are obtained by applying the coating composition according to claim 1 to the seeds and drying the thus-applied coating.

3. The method according to claim 2, characterized in that The encapsulated seeds have an average bulk dust shedding property of less than 0.1 g / 100,000 seeds.

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