Coating material for controlled release agent, controlled release agent, granular fertilizer or granular pesticide coated therewith

Abstract

To provide a coating material for a sustained release agent, using lignin derived from a plant, and a sustained release agent, a granular fertilizer or a granular agricultural chemical coated with the same.SOLUTION: A coating material for a sustained release agent, including lignin, a cationic polymer, and a solvent, is characterized in that lignin and the cationic polymer are blended in a weight ratio of from 99.9 / 0.1 to 0.1 to 99.9. A sustained release agent, a granular fertilizer or a granular agricultural chemical is prepared by coating a coating object with the coating material.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a coating material for a sustained-release agent containing lignin, and a granular fertilizer or granular pesticide coated therewith.

Background Art

[0002] In the case of agricultural chemicals and fertilizers, there has been a demand for reducing the number of sprayings (labor saving) and the adverse effects (phytotoxicity) of agricultural chemicals on crops has been a problem. In response to these problems, technical research has been conducted on agents (sustained-release agents) that can control the amount (rate) of elution of agricultural chemical and fertilizer components from granules to maintain the effects of agricultural chemicals and fertilizers for a long period of time, or suppress the elution amount below a certain level.

[0003] As a technique for controlling the elution rate of agricultural chemicals and fertilizers and making the effects of agricultural chemicals last longer, there is a technique of coating agricultural chemicals and fertilizers with a resin material or the like, or kneading a resin material or the like with agricultural chemicals and fertilizers to suppress the elution of active ingredients below a certain amount (impart sustained release properties) and using it as a sustained-release agent (for example, Patent Document 1, Patent Document 2).

[0004] In Patent Document 1, a release control agent for an active ingredient for agricultural chemicals containing a resin component such as polyester is disclosed, and in Patent Document 2, a fiber composite resin composition having sustained release properties using a resin such as polypropylene and a fibrous filler is disclosed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Even with the invention disclosed in the above patent document, it is possible to impart sustained release properties to pesticides and fertilizers. However, these contain resin components such as polyester and polypropylene, and these remain in the environment without being decomposed, causing soil pollution. In addition, the above resin components are petroleum-derived components, and from the perspective of environmental load, it is more desirable to use bio-derived resources.

[0007] Therefore, an object of the present invention is to provide a coating material for a sustained release agent using plant-derived lignin, and a sustained release agent, granular fertilizer or granular pesticide coated therewith.

Means for Solving the Problems

[0008] (1) A coating material for a sustained release agent comprising lignin, a cationic polymer and a solvent, wherein the lignin and the cationic polymer are blended at a weight ratio of 99.9 / 0.1 to 0.1 / 99.9. (2) The coating material for a sustained release agent according to (1), wherein the lignin is lignin sulfonic acid or a salt thereof. (3) The coating material for a sustained release agent according to (2), wherein the sulfonic acid group content of the lignin is 1.5% by weight or more. (4) The coating material for a sustained release agent according to any one of (1) to (3), wherein the weight average molecular weight of the lignin is 1,000 or more and 10 million or less. (5) The coating material for a sustained release agent according to any one of (1) to (4), wherein the cationic polymer contains at least a polymer having an amino group or a polymer of a quaternary ammonium salt. (6) A sustained release agent obtained by coating an object to be coated with the coating material for a sustained release agent according to any one of (1) to (5). (7) A granular fertilizer or granular pesticide obtained by coating an object to be coated with the coating material for a sustained release agent according to any one of (1) to (5).

Effects of the Invention

[0009] According to the present invention, it is possible to obtain a coating material for a sustained release agent having sustained release properties while suppressing environmental load, and a sustained release agent, granular fertilizer or granular pesticide obtained by coating an object to be coated therewith.

Best Mode for Carrying Out the Invention

[0010] Hereinafter, the present invention will be described in detail according to its preferred embodiments. However, the present invention is not limited to the following embodiments at all. In this specification, the notation "AA to BB" means AA or more and BB or less.

[0011] The coating material for the sustained-release agent in the present invention contains at least lignin, a cationic polymer, and a solvent.

[0012] (Lignin) As the lignin used in the present invention, the methoxyl group content per solid content is preferably 3 to 20% by weight. When the methoxyl group content is 3% or less, the amount of lignin contained is small, so the formation of the polyion complex described later becomes insufficient, and the sustained-release effect cannot be obtained sufficiently. Generally, since lignin has methoxyl groups bonded to the aromatic nucleus, the methoxyl group content serves as an index of the lignin content. Usually, the methoxyl group content varies depending on the type of lignocellulose biomass. In lignin derived from softwood, 3 to 12% of methoxyl groups are present per solid content, and in lignin derived from hardwood, 8 to 20% of methoxyl groups are present per solid content.

[0013] In the present invention, the methoxyl group content is a value measured by the method for quantifying methoxyl groups by the Viebock and Schwappach method (refer to "Research Methods of Lignin Chemistry", pp. 336 to 340, published by Yuni Publishing Co., Ltd. in 1994).

[0014] (Amount of phenolic hydroxyl groups) The amount of phenolic hydroxyl groups relative to the structural unit derived from the lignin compound is usually 1.5% or more, preferably 1.6% or more, more preferably 1.7% or more. The upper limit is usually 6.0% or less, preferably 5.5% or less, more preferably 5.0% or less. Therefore, the amount of phenolic hydroxyl groups is usually 1.5 to 6.0%, preferably 1.6 to 5.5%, more preferably 1.7 to 5.0%. When the lignin compound is kraft lignin, the lower limit of the amount of phenolic hydroxyl groups is more preferably 2.0% or more, and particularly preferably more than 2.5%. When the amount of phenolic hydroxyl groups is within the above range, the dispersibility of the dispersion can be further improved. The amount of phenolic hydroxyl groups can be adjusted according to the raw material of the lignin compound (for example, either hardwood or softwood, or the tree species), the preparation method (the method for preparing lignin compounds such as lignosulfonic acid and kraft lignin from pulp), and the preparation conditions (the implementation conditions in the above preparation method: for example, cooking temperature, pressure, and time).

[0015] The measurement of the amount of phenolic hydroxyl groups can be carried out by measuring the differential absorption coefficient near 300 nm using a spectrophotometer, and this method is also used for measurement in the examples described later. For example, an ionization differential spectrum can be obtained by subtracting the absorption spectrum of a neutral solution containing lignin at the same concentration from the absorption spectrum of an alkaline solution containing a lignin sample, and the phenolic hydroxyl group (%) can be determined from the following formula. Δαmax [L / (g·cm)] represents the differential absorption coefficient (Nakano Junzo, ed., "Chemistry of Lignin - Basics and Applications - Revised and Enlarged Edition", published by Yuni Publishing, issued on May 25, 1990, page 541).

[0016]

Equation

[0017] The lignin used in the present invention varies depending on the method for treating lignocellulosic biomass, and there are various types. Examples of such lignin include the following lignins. For example, lignosulfonic acid, kraft lignin, soda lignin, soda-anthraquinone lignin, organosolv lignin, crushed lignin, sulfuric acid lignin, and the like. Among these, it is preferable to use lignosulfonic acid and kraft lignin.

[0018] As the lignin used in the present invention, a mixture of one or more of the above lignins may also be used.

[0019] Hereinafter, as examples of the lignin used in the present invention, lignosulfonic acid and kraft lignin will be described in detail. However, the lignin of the present invention is not limited thereto, and derivatives of lignin are also included therein.

[0020] (Lignosulfonic acid) Lignosulfonic acid refers to a compound in which at least a part of lignin or its decomposition product is substituted with a sulfonic acid (salt) group. The lignosulfonic acid of the present invention usually has an S content of the sulfonic acid (salt) group of 1.0 to 6.0% by weight.

[0021] The S content of the sulfonic acid (salt) group of lignosulfonic acid refers to the S content contained in the sulfonic acid (salt) group with respect to the solid content of lignosulfonic acid. Specifically, it is a value calculated from the following formula (2). Formula (2): S content of sulfonic acid (salt) group (% by weight) = total S content (% by weight) - inorganic S content (% by weight) (In formula (2), the S content indicates the S content with respect to the solid content of lignosulfonic acid.)

[0022] In formula (2), the total S content can be quantified by ICP emission spectrometry. Also, the inorganic S content can be calculated as the total amount of the SO3 content and the SO4 content quantified by ion chromatography.

[0023] The lignosulfonic acid used in the present invention contains reducing sugars. Reducing sugars generally remain in the process of sulfite cooking of lignocellulose biomass. Reducing sugars are usually contained in an amount of 0.01 to 20.0% by weight.

[0024] A reducing sugar refers to a sugar that exhibits reducibility and is a sugar that generates an aldehyde group or a ketone group in a basic solution. Examples of reducing sugars include all monosaccharides, disaccharides such as maltose, lactose, arabinose, and invert sugar of sucrose, and polysaccharides. Reducing sugars contained in alkaline treatment effluent usually include cellulose, hemicellulose, and their degradation products. Examples of degradation products of cellulose and hemicellulose include monosaccharides such as rhamnose, galactose, arabinose, xylose, glucose, mannose, and fructose; and oligosaccharides such as xylooligosaccharide and cellooligosaccharide. The measurement of reducing sugar can be measured by the Somogyi-Schaffer method, and the content of reducing sugar can be obtained by converting the measured value into the amount of glucose.

[0025] Lignin sulfonic acid may be in an un-ionized state, or the hydrogen atom of the sulfonic acid group may be substituted with a counter ion. Examples of counter ions include sodium ion, calcium ion, magnesium ion, ammonium ion, etc. Note that the counter ion may be a single type of counter ion, or a combination of two or more types of counter ions.

[0026] The lignin sulfonic acid of the present invention usually contains inorganic salts. Examples of inorganic salts include sodium sulfate, sodium sulfite, sodium chloride, magnesium sulfate, magnesium sulfite, magnesium chloride, calcium sulfate, calcium sulfite, calcium chloride, ammonium sulfate, ammonium sulfite, ammonium chloride, and sodium hydroxide. The content of inorganic salts in lignin sulfonic acid is usually 1 to 25% by weight.

[0027] As the lignosulfonic acid used in the present invention, those prepared may be used, or commercially available products may be used. Examples of commercially available products include Sun Extract M-100, Sun Extract P202, Sun Extract P252, Sun Extract P321, Sun Extract SCP, Sunflow RH, Vanilex HW, Vanilex N, Vanilex RN, Pearllex NP, and Pearllex DP (all manufactured by Nippon Paper Industries). Further, although the preparation method will be exemplified below, it is not limited to those prepared by the following preparation method.

[0028] (Preparation Method of Lignosulfonic Acid) Lignosulfonic acid can be prepared, for example, by subjecting a lignocellulosic raw material to sulfite treatment. Among them, it is preferable to prepare by subjecting the lignocellulosic raw material to sulfite digestion treatment.

[0029] The lignocellulosic raw material is not particularly limited as long as it contains lignocellulose in its composition. For example, pulp raw materials such as wood and non-wood can be mentioned. Examples of wood include coniferous woods such as Pinus koraiensis, Pinus densiflora, Cryptomeria japonica, and Chamaecyparis obtusa, and broad-leaved woods such as Betula platyphylla and Fagus crenata. The tree age and collection site of the wood are not limited. Therefore, woods collected from trees with different tree ages or woods collected from different parts of the tree may be combined and used. Examples of non-wood include bamboo, kenaf, reed, and rice. The lignocellulosic raw material may be used alone or in combination of two or more of these materials.

[0030] The sulfite treatment can be carried out by bringing at least one of sulfite and sulfite salt into contact with the lignocellulosic raw material, and it is a treatment for obtaining an intermediate product. The conditions of the sulfite treatment are not particularly limited as long as they are conditions under which a sulfonic acid (salt) group can be introduced into the α-carbon atom of the side chain of lignin contained in the lignocellulosic raw material.

[0031] The sulfurous acid treatment is preferably carried out by the sulfurous acid digestion method. Thereby, lignin in the lignocellulosic raw material can be more quantitatively sulfonated. The sulfurous acid digestion method is a method of reacting a lignocellulosic raw material in a solution of at least one of sulfurous acid and sulfite (for example, an aqueous solution: a cooking liquor) at a high temperature. This method has been industrially established and implemented as a method for producing sulfite pulp. Therefore, by carrying out the sulfurous acid treatment by the sulfurous acid digestion method, the economy and ease of implementation can be enhanced.

[0032] As salts of sulfite, when performing sulfurous acid digestion, for example, magnesium salts, calcium salts, sodium salts, and ammonium salts can be mentioned.

[0033] The concentration of sulfurous acid (SO2) in the solution of at least one of sulfurous acid and sulfite is not particularly limited, but the ratio of the mass (g) of SO2 to 100 mL of the reaction chemical solution is preferably 1 g / 100 mL or more, and more preferably 2 g / 100 mL or more when performing sulfurous acid digestion. The upper limit is preferably 20 g / 100 mL or less, and more preferably 15 g / 100 mL or less when performing sulfurous acid digestion. The SO2 concentration is preferably 1 g / 100 mL to 20 g / 100 mL, and more preferably 2 g / 100 mL to 15 g / 100 mL when performing sulfurous acid digestion.

[0034] The pH value of the sulfurous acid treatment is not particularly limited, but is preferably 10 or less, and more preferably 5 or less when performing sulfurous acid digestion. The lower limit of the pH value is preferably 0.1 or more, and more preferably 0.5 or more when performing sulfurous acid digestion. The pH value during the sulfurous acid treatment is preferably 0.1 to 10, and more preferably 0.5 to 5 when performing sulfurous acid digestion.

[0035] The temperature of the sulfurous acid treatment is not particularly limited, but is preferably 170 °C or less, and more preferably 150 °C or less when performing sulfurous acid digestion. The lower limit is preferably 70 °C or more, and more preferably 100 °C or more when performing sulfurous acid digestion. The temperature condition of the sulfurous acid treatment is preferably 70 to 170 °C, and more preferably 100 °C to 150 °C when performing sulfurous acid digestion.

[0036] The treatment time of the sulfite treatment is not particularly limited, and although it depends on the various conditions of the sulfite treatment, it is preferably 0.5 to 24 hours, and more preferably 1.0 to 12 hours.

[0037] In the sulfite treatment, it is preferable to add a compound that supplies a counter cation (salt). By adding a compound that supplies a counter cation, the pH value in the sulfite treatment can be kept constant. Examples of the compound that supplies a counter cation include MgO, Mg(OH)2, CaO, Ca(OH)2, CaCO3, NH3, NH4OH, NaOH, NaHCO3, and Na2CO3. The counter cation is preferably a magnesium ion.

[0038] When using at least one solution of sulfurous acid and sulfite in the sulfite treatment, the solution may contain, if necessary, in addition to SO2 and a counter cation (salt), a delignification penetrant (for example, a cyclic ketone compound such as anthraquinone sulfonate, anthraquinone, tetrahydroanthraquinone, etc.).

[0039] There is no limitation on the equipment used when performing the sulfite treatment. For example, generally known equipment for producing dissolved pulp can be used.

[0040] To separate an intermediate product from at least one solution of sulfurous acid and sulfite, it may be carried out according to a conventional method For example, the separation method of the sulfite digestion effluent after sulfite digestion can be mentioned.

[0041] The sulfonic acid group content in the lignin of the present invention is preferably 1.5% by weight or more. If it is less than 1.5% by weight, the PIC film will not be continuous, and fertilizers and the like may ooze out from the voids, and sufficient sustained release may not be ensured. The sulfonic acid group content is more preferably 2.0 to 40% by weight, and particularly preferably 3.0 to 30% by weight. ​

[0042] According to the sulfite cooking treatment, lignin sulfonic acid with a high sulfonic acid content may be obtained. In that case, it is possible to adjust the sulfonic acid content by a partial desulfonation treatment. Examples of the partial desulfonation method include, but are not limited to, the methods described in JP-A-58-45287.

[0043] Also, according to the method described in JP 2016-135834, it is similarly possible to adjust the sulfonic acid content.

[0044] The lignin sulfonic acid group content (wt%) was calculated based on the amount of methoxyl groups present in 10 mg of the sample according to the method for determining methoxyl groups described in Method in Ligin Chemistry (supervised by Junzo Nakano, Yuni Publishing Co., Ltd.), and converted to the lignin content (wt%).

[0045] (Kraft lignin) As the lignin or lignin derivative of the present invention, Kraft Lignin can be used. The above Kraft lignin is also known as ThioLignin and SulphateLignin. As the Kraft lignin, those prepared or commercially available products may be used. As the adjustment method, an alkaline solution of Kraft lignin, powdered Kraft lignin obtained by spray-drying an alkaline solution of Kraft lignin, or acid-precipitated Kraft lignin obtained by precipitating an alkaline solution of Kraft lignin with an acid can be used.

[0046] The alkaline solution of Kraft lignin can be obtained by known methods such as those described in JP 2000-336589, but is not limited to these methods.

[0047] Kraft lignin usually contains reducing sugars and inorganic salts. The respective contents are as exemplified in the above item of lignin sulfonic acid.

[0048] As the acid-precipitated kraft lignin obtained by precipitating an alkaline solution of kraft lignin with an acid, powdery acid-precipitated kraft lignin obtained by methods described in WO2006 / 038863, WO2006 / 031175, WO2012 / 005677, etc. can be used, but it is not limited to these methods.

[0049] Sulfonated lignin obtained by sulfonating the above-mentioned kraft lignin may also be used. For example, sulfomethylated sulfomethylated kraft lignin and sulfonated lignin described in US5049661 can be mentioned according to the method described in "Research on the Utilization of Lignin (Report 3) On the Sulfomethylation of Thiolignin; Yasushi Oda, Junzo Nakano, Nobuhiko Ueda: Journal of the Wood Research Society, Vol. 12, No. 5, 239-244 (1966)".

[0050] As the sulfonated lignin, the prepared one may be used, or a commercially available product may be used. Examples of commercially available products include POLYFON and REAX (both manufactured by Ingevity).

[0051] The weight-average molecular weight of the lignin used in the present invention is preferably from 1,000 to 10,000,000, more preferably from 5,000 to 8,000,000, and particularly preferably from 5,000 to 5,000,000. When the weight-average molecular weight is less than 1,000, polyion complex formation becomes insufficient, and when it exceeds 10,000,000, aggregates are likely to occur.

[0052] The weight-average molecular weight can be measured by a known method in terms of polyethylene glycol conversion using gel permeation chromatography (GPC). The measurement conditions of GPC are not particularly limited, and for example, the following conditions can be mentioned. The weight-average molecular weight in the following examples was measured under these conditions.

[0053] Measuring device; manufactured by Tosoh Column used; Shodex Column OH-pak SB-806HQ, SB-804HQ, SB-802.5HQ Eluent; 0.05 mM sodium nitrate / acetonitrile 8 / 2 (v / v) Standard substance; polyethylene glycol (manufactured by Tosoh Corporation or GL Sciences Inc.) Detector; differential refractometer (manufactured by Tosoh Corporation) Calibration curve; based on polyethylene glycol

[0054] <Cationic polymer> Regarding the cationic polymer, those of natural origin or synthetic origin can be used regardless. For example, polymers having an amino group or polymers of quaternary ammonium salts, cationized celluloses, cationized starches, etc. can be used, and examples of such substances include dicyandiamide-formaldehyde resins, diethylenetriamine-dicyandiamide-ammonium chloride condensates, polymers of (meth)acryloyloxyalkyltrialkylammonium chloride, polymers of diallyldimethylammonium chloride, ethyleneimine polymers, diallylamine polymers, ammonia-epichlorohydrin-dimethylamine copolymers, polyacrylamide-based resins, polymethacrylate-based resins, polyacrylate-based resins, cationized cellulose, cationized starch, etc.

[0055] Also, two or more cationic polymers can be used in combination.

[0056] Among these, as the coating material for the sustained-release agent of the present invention, it is preferable from the viewpoint of polyion complex formation that the cationic polymer contains at least a polymer having an amino group or a polymer of a quaternary ammonium salt. Examples of such cationic polymers include polymers of diallyldimethylammonium chloride and their salts, polymers of methacryloyloxyethyltrimethylammonium and their salts, polymers of vinyltrimethylammonium and their salts, polymers of methacryloethyltrimethylammonium and their salts, etc., which are preferably used.

[0057] The weight average molecular weight of the cationic polymer is preferably 10,000 or more, more preferably 50,000 or more, and particularly preferably 150,000 or more. As the upper limit, 1,000,000 or less is preferable, 800,000 or less is more preferable, 600,000 or less is further preferable, and 400,000 or less is particularly preferable. When the lower limit value is less than 10,000, thickening or solidification by polyion complex formation may be insufficient, and when the upper limit value is 10,000,000 or more, coating may be difficult due to aggregation.

[0058] The weight average molecular weight of the cationic polymer can be obtained in the same manner as the measurement method in lignin described above.

[0059] <Solvent> The solvent used as the solvent of the present invention is typically water, but other solvents can also be used as long as the effects of the present invention are not inhibited, and organic solvents such as xylene, methyl alcohol, ethyl alcohol, isopropyl alcohol, glycerin, ethylene glycol, propylene glycol, propylene glycol monomethyl ether, and methylnaphthalene can also be used. The solvent is preferably water from the viewpoints of VOC reduction and price. In addition, the solvent may be used alone or in combination of a plurality of solvents.

[0060] <Sustained-release coating material> The sustained-release coating material of the present invention contains the lignin, cationic polymer, and solvent described above. The lignin and cationic polymer of the present invention are blended in a weight ratio of 99.9 / 0.1 to 0.1 / 99.9.

[0061] When the total amount of lignin and cationic polymer is 100 parts, the blending amount of the solvent is preferably 1 to 99,900 parts, and more preferably 1 to 9,900 parts.

[0062] The sustained-release coating material of the present invention thickens or solidifies by mixing the content components so that lignin (an anionic substance) and a cationic polymer approach each other and form a polyion complex. When this polyion complex is applied to a coated object such as a granule of fertilizer or pesticide or a slurry, and then the solvent volatilizes by drying or the like, a film is formed on the surface of the coated object. In the formation of the film, a film composed only of the polyion complex may be formed on the surface of the coated object, but there are also cases where the polyion complex penetrates into the coated object and a film is formed in a state where the polyion complex and the components of the coated object are mixed. In the present invention, in any case, it is expressed as "a film is formed" or "coated". The film thus formed has sustained release properties because the polyion complex softens and disintegrates when it comes into contact with water or the like, and the fertilizer or the like gradually oozes out from the disintegrated portion. It is particularly useful as a coating material for imparting sustained release properties to pesticides, fertilizers, and the like.

[0063] The content ratio of lignin to the cationic polymer is 99.9 / 0.1 to 0.1 / 99.9 (weight ratio). However, from the viewpoint of generating a sufficient increase in viscosity when forming a film by drying and exhibiting sufficient sustained release properties, the content ratio of lignin to the cationic polymer is more preferably 97 / 3 to 10 / 90 (weight ratio), and particularly preferably 95 / 5 to 20 / 80 (weight ratio).

[0064] The sustained-release coating material of the present invention can contain other components other than the aforementioned lignin, cationic polymer, and solvent, as long as the effects of the present invention are not inhibited. Such other components can be widely used as long as they are generally used in various fertilizers and pesticide formulations. Examples thereof include anionic surfactants such as alkyl sulfates, alkyl aryl sulfonic acids, alkyl sulfonic acids, polyethylene glycol ethers, polyethylene glycol esters, and polyhydric alcohol esters, nonionic surfactants, various salts, polymer adhesives, plasticizers, dispersants, surfactants, thickeners, viscosity modifiers, preservatives, colorants, deodorants, antioxidants, ultraviolet absorbers, hydrolysis inhibitors, physical property improvers, and the like. In addition, the bulking agent that can be used in the present invention can be used as long as it is generally used in fertilizers and pesticide formulations. Examples thereof include minerals such as clay, kaolin, sericite, zeolite, talc, acid clay, calcium carbonate, magnesium carbonate, gypsum, diatomaceous earth, pumice, zeolite, perlite, vermiculite, attapulgite, bentonite, and natural products such as starch and cellulose.

[0065] When other components are contained in the sustained-release coating material of the present invention, it is preferably 10% by weight or less, more preferably 5% by weight or less, based on the total solid content of the sustained-release coating material. When the other components are outside this range, problems such as insufficient increase in viscosity when forming a film by drying, failure to exhibit sustained release, and stickiness on the surface of the granular material may occur.

[0066] The sustained-release coating material of the present invention is preferably used in the form of a colloidal aqueous solution containing lignin, a cationic polymer, and a solvent. As a method for preparing such a colloidal aqueous solution, for example, a method can be mentioned in which an aqueous solution containing lignin and an aqueous solution containing a cationic polymer are prepared, and then the aqueous solution containing the cationic polymer is added and mixed while stirring the aqueous solution containing lignin.

[0067] The colloidal aqueous solution thus obtained preferably has a solid content concentration of 1% by weight or more, more preferably 5% by weight or more. The upper limit is preferably 80% by weight or less, more preferably 30% by weight or less, and even more preferably 20% by weight or less.

[0068] When the solid content concentration is 1% by weight or more, the polyion complex thickens or solidifies to form a film on the surface of the object to be coated, which is suitable for the present invention. When the solid content concentration exceeds 80% by weight, the viscosity increases significantly and mixing becomes difficult.

[0069] <Object to be coated> In the present invention, the object to be coated (carrier) is typically a pesticide, a fertilizer, or a carrier holding these, but is not limited thereto, and any object that requires control of component elution or whose durability and sustained release properties are improved by coating can be preferably used. Specifically, pharmaceuticals and the like can be used as the object to be coated.

Example

[0070] Hereinafter, the present invention will be described with reference to examples, but the scope of the present invention is not limited thereto. Unless otherwise specified in the examples, % represents weight %, and parts represent parts by weight.

[0071] (Lignin mixture 1) Sun extract M-100 (an aqueous solution containing magnesium lignosulfonate and water, manufactured by Nippon Paper Industries Co., Ltd., molecular weight 11,700, sulfonic acid group content 5.0% by weight) was used as lignin mixture 1. (Lignin mixture 2) Reagent Lignin alkali (manufactured by ALDRICH, molecular weight 12,200, sulfonic acid group content 0.6% by weight) was used as lignin mixture 2.

[0072] (Cationic polymer 1) An aqueous solution with a solid content concentration of 20% by weight of polydiallyldimethylammonium chloride (manufactured by Merck, weight average molecular weight 200,000 - 350,000) was used as cationic polymer 1.

[0073] (Object to be coated) As the object to be coated, 84 parts of kaolin, 15 parts of bentonite, and 50 parts of a 2% by weight aqueous solution of an ethylene oxide adduct of methallyl alcohol (average number of moles of ethylene oxide added: 53, weight average molecular weight 2404) were added and kneaded uniformly. After cutting this into pieces with a diameter of 3 mm and a length of 5 mm, it was dried at 105 °C for 30 minutes and then at 50 °C for 16 hours to obtain object to be coated 1.

[0074] (Example 1) While stirring and mixing, 1 (90% by weight) of a lignin mixture and pure water were added to 1 (10% by weight) of a cationic polymer to obtain 1 (a sustained-release coating material. Lignin sulfonic acid: cationic polymer = 90:10 (weight ratio)) of a colloidal aqueous solution having a solid content concentration of 1% by weight. With respect to 1 part by weight of the object to be coated 1, 10 parts by weight of the colloidal aqueous solution 1 was added, and after allowing the colloidal aqueous solution to infiltrate for 1 minute, the object to be coated 1 infiltrated with the colloidal aqueous solution was dried at 105 ° C for 30 minutes to obtain granular materials. The obtained granular materials were evaluated for the following coating properties and water disintegration properties tests. The results are shown in Table 1.

[0075] <Coating property> The appearance of the granular materials obtained in Example 1 (the presence or absence of voids where the object to be coated was not coated with a polyion complex) was visually confirmed. 〇: No voids after drying. △: Voids of 50% or less of the surface area of the granular material exist after drying. ×: Voids exceeding 50% of the surface area of the granular material exist after drying.

[0076] <Water disintegration property test> The carrier flow was measured by the following test. The carrier flow is used as an index (an index indicating sustained release) showing the rate at which active ingredients such as fertilizers and pesticides elute. The granular materials obtained in Example 1 were gently placed in a container filled with ion-exchanged water, and after 30 minutes and 1 hour, respectively, the distance at which the object to be coated eluted from the granular materials was visually confirmed. Then, the eluted distance was measured with a ruler, and the measured distance was evaluated as the carrier flow (the distance eluted vertically (cm) × the distance eluted horizontally (cm)).

[0077] (Example 2) Granular materials were obtained in the same manner as in Example 1 except that the amount of the colloidal aqueous solution 1 added was 5% by weight with respect to 100 parts by weight of the object to be coated 1, and the coating properties and water disintegration properties tests were evaluated. The results are shown in Table 1.

[0078] (Example 3) A granular material was obtained in the same manner as in Example 1 except that the ratio of the lignin mixture 1 and the cationic polymer 1 to be stirred and mixed was 50% by weight each, and the evaluation of the coating property and the water disintegration property test was carried out. The results are shown in Table 1.

[0079] (Example 4) To the lignin mixture 2 (90% by weight), the cationic polymer 1 (10% by weight) was gradually added while stirring and mixing to obtain a colloidal aqueous solution 2 having a solid content concentration of 1% by weight (sustained-release coating material. Lignin sulfonic acid: cationic polymer = 90:10 (weight ratio)). To 1 part by weight of the object to be coated 1, 10 parts by weight of the colloidal aqueous solution 2 was added, and after infiltrating the colloidal aqueous solution for 1 minute, the object to be coated 1 infiltrated with the colloidal aqueous solution was dried at 105 ° C for 30 minutes to obtain a granular material. For the obtained granular material, the evaluation of the coating property and the water disintegration property test was carried out in the same manner as in Example 1. The results are shown in Table 1.

[0080] (Comparative Example 1) For the object to be coated 1, the evaluation of the coating property and the water disintegration property test was carried out without coating with the colloidal aqueous solution (sustained-release coating material). The results are shown in Table 1.

[0081]

Table 1

[0082] As shown in Table 1, in Examples 1 to 4 of the present invention, the carrier flow value of the water disintegration property test tended to be improved, and it was confirmed that they had higher sustained-release properties.

Claims

1. A coating material for a sustained-release agent, comprising lignin sulfonic acid or a salt thereof, a cationic polymer which is a polymer having an amino group or a polymer of a quaternary ammonium salt, and a solvent, wherein the lignin sulfonic acid or a salt thereof and the cationic polymer are blended at a weight ratio of 95 / 5 to 20 / 80.

2. The coating material for a sustained-release agent according to Claim 1, wherein the sulfonic acid group content of the lignin sulfonic acid or a salt thereof is 3.0 to 30% by weight or more.

3. The coating material for a sustained-release agent according to any one of Claims 1 to 2, wherein the weight average molecular weight of the lignin sulfonic acid is 5,000 to 5 million.

4. The coating material for a sustained-release agent according to any one of Claims 1 to 3, wherein the cationic polymer is polydiallyldimethylammonium chloride.

5. A sustained-release agent obtained by coating an object to be coated with the coating material for a sustained-release agent according to any one of Claims 1 to 4.

6. A granular fertilizer or a granular pesticide obtained by coating an object to be coated with the coating material for a sustained-release agent according to any one of Claims 1 to 4.

Images